blob: 385d48293a5fa152bfb3e7e30a074cab3fd019db [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
3 * linux/kernel/seccomp.c
4 *
5 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 *
Will Drewrye2cfabdf2012-04-12 16:47:57 -05007 * Copyright (C) 2012 Google, Inc.
8 * Will Drewry <wad@chromium.org>
9 *
10 * This defines a simple but solid secure-computing facility.
11 *
12 * Mode 1 uses a fixed list of allowed system calls.
13 * Mode 2 allows user-defined system call filters in the form
14 * of Berkeley Packet Filters/Linux Socket Filters.
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 */
Kees Cooke68f9d42020-06-15 22:02:56 -070016#define pr_fmt(fmt) "seccomp: " fmt
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
Kees Cook0b5fa222017-06-26 09:24:00 -070018#include <linux/refcount.h>
Eric Paris85e7bac32012-01-03 14:23:05 -050019#include <linux/audit.h>
Roland McGrath5b101742009-02-27 23:25:54 -080020#include <linux/compat.h>
Mike Frysingerb25e6712017-01-19 22:28:57 -060021#include <linux/coredump.h>
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +000022#include <linux/kmemleak.h>
Kees Cook5c307082018-05-01 15:07:31 -070023#include <linux/nospec.h>
24#include <linux/prctl.h>
Will Drewrye2cfabdf2012-04-12 16:47:57 -050025#include <linux/sched.h>
Ingo Molnar68db0cf2017-02-08 18:51:37 +010026#include <linux/sched/task_stack.h>
Will Drewrye2cfabdf2012-04-12 16:47:57 -050027#include <linux/seccomp.h>
Kees Cookc8bee432014-06-27 15:16:33 -070028#include <linux/slab.h>
Kees Cook48dc92b2014-06-25 16:08:24 -070029#include <linux/syscalls.h>
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +000030#include <linux/sysctl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Kees Cook495ac302022-02-07 20:21:13 -080032/* Not exposed in headers: strictly internal use only. */
33#define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
34
Andy Lutomirskia4412fc2014-07-21 18:49:14 -070035#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
Will Drewrye2cfabdf2012-04-12 16:47:57 -050036#include <asm/syscall.h>
Andy Lutomirskia4412fc2014-07-21 18:49:14 -070037#endif
Will Drewrye2cfabdf2012-04-12 16:47:57 -050038
39#ifdef CONFIG_SECCOMP_FILTER
Tycho Andersen6a21cc52018-12-09 11:24:13 -070040#include <linux/file.h>
Will Drewrye2cfabdf2012-04-12 16:47:57 -050041#include <linux/filter.h>
Kees Cookc2e1f2e2014-06-05 00:23:17 -070042#include <linux/pid.h>
Will Drewryfb0fadf2012-04-12 16:48:02 -050043#include <linux/ptrace.h>
Mickaël Salaünfb145282020-10-30 13:38:49 +010044#include <linux/capability.h>
Will Drewrye2cfabdf2012-04-12 16:47:57 -050045#include <linux/uaccess.h>
Tycho Andersen6a21cc52018-12-09 11:24:13 -070046#include <linux/anon_inodes.h>
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -070047#include <linux/lockdep.h>
Tycho Andersen6a21cc52018-12-09 11:24:13 -070048
Kees Cook47e33c052020-06-15 15:42:46 -070049/*
50 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
51 * wrong direction flag in the ioctl number. This is the broken one,
52 * which the kernel needs to keep supporting until all userspaces stop
53 * using the wrong command number.
54 */
55#define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
56
Tycho Andersen6a21cc52018-12-09 11:24:13 -070057enum notify_state {
58 SECCOMP_NOTIFY_INIT,
59 SECCOMP_NOTIFY_SENT,
60 SECCOMP_NOTIFY_REPLIED,
61};
62
63struct seccomp_knotif {
64 /* The struct pid of the task whose filter triggered the notification */
65 struct task_struct *task;
66
67 /* The "cookie" for this request; this is unique for this filter. */
68 u64 id;
69
70 /*
71 * The seccomp data. This pointer is valid the entire time this
72 * notification is active, since it comes from __seccomp_filter which
73 * eclipses the entire lifecycle here.
74 */
75 const struct seccomp_data *data;
76
77 /*
78 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
79 * struct seccomp_knotif is created and starts out in INIT. Once the
80 * handler reads the notification off of an FD, it transitions to SENT.
81 * If a signal is received the state transitions back to INIT and
82 * another message is sent. When the userspace handler replies, state
83 * transitions to REPLIED.
84 */
85 enum notify_state state;
86
87 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
88 int error;
89 long val;
Christian Braunerfb3c53862019-09-20 10:30:05 +020090 u32 flags;
Tycho Andersen6a21cc52018-12-09 11:24:13 -070091
Sargun Dhillon7cf97b12020-06-02 18:10:43 -070092 /*
93 * Signals when this has changed states, such as the listener
94 * dying, a new seccomp addfd message, or changing to REPLIED
95 */
Tycho Andersen6a21cc52018-12-09 11:24:13 -070096 struct completion ready;
97
98 struct list_head list;
Sargun Dhillon7cf97b12020-06-02 18:10:43 -070099
100 /* outstanding addfd requests */
101 struct list_head addfd;
102};
103
104/**
105 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
106 *
107 * @file: A reference to the file to install in the other task
108 * @fd: The fd number to install it at. If the fd number is -1, it means the
109 * installing process should allocate the fd as normal.
110 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
111 * is allowed.
Rodrigo Campos0ae71c72021-05-17 12:39:07 -0700112 * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
Kees Cook46822862023-08-17 12:32:15 -0700113 * @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd
Sargun Dhillon7cf97b12020-06-02 18:10:43 -0700114 * @ret: The return value of the installing process. It is set to the fd num
115 * upon success (>= 0).
116 * @completion: Indicates that the installing process has completed fd
117 * installation, or gone away (either due to successful
118 * reply, or signal)
Kees Cook46822862023-08-17 12:32:15 -0700119 * @list: list_head for chaining seccomp_kaddfd together.
Sargun Dhillon7cf97b12020-06-02 18:10:43 -0700120 *
121 */
122struct seccomp_kaddfd {
123 struct file *file;
124 int fd;
125 unsigned int flags;
Rodrigo Campos0ae71c72021-05-17 12:39:07 -0700126 __u32 ioctl_flags;
Sargun Dhillon7cf97b12020-06-02 18:10:43 -0700127
Christoph Hellwig42eb0d52021-03-25 09:22:09 +0100128 union {
129 bool setfd;
130 /* To only be set on reply */
131 int ret;
132 };
Sargun Dhillon7cf97b12020-06-02 18:10:43 -0700133 struct completion completion;
134 struct list_head list;
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700135};
136
137/**
138 * struct notification - container for seccomp userspace notifications. Since
139 * most seccomp filters will not have notification listeners attached and this
140 * structure is fairly large, we store the notification-specific stuff in a
141 * separate structure.
142 *
Kees Cook46822862023-08-17 12:32:15 -0700143 * @requests: A semaphore that users of this notification can wait on for
144 * changes. Actual reads and writes are still controlled with
145 * filter->notify_lock.
146 * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags.
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700147 * @next_id: The id of the next request.
148 * @notifications: A list of struct seccomp_knotif elements.
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700149 */
Andrei Vagin48a10842023-03-07 23:31:59 -0800150
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700151struct notification {
Andrei Vagin4943b662023-03-07 23:31:56 -0800152 atomic_t requests;
Andrei Vagin48a10842023-03-07 23:31:59 -0800153 u32 flags;
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700154 u64 next_id;
155 struct list_head notifications;
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700156};
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500157
YiFei Zhuf9d480b2020-10-11 10:47:42 -0500158#ifdef SECCOMP_ARCH_NATIVE
159/**
160 * struct action_cache - per-filter cache of seccomp actions per
161 * arch/syscall pair
162 *
163 * @allow_native: A bitmap where each bit represents whether the
164 * filter will always allow the syscall, for the
165 * native architecture.
166 * @allow_compat: A bitmap where each bit represents whether the
167 * filter will always allow the syscall, for the
168 * compat architecture.
169 */
170struct action_cache {
171 DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
172#ifdef SECCOMP_ARCH_COMPAT
173 DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
174#endif
175};
176#else
177struct action_cache { };
178
179static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
180 const struct seccomp_data *sd)
181{
182 return false;
183}
YiFei Zhu8e01b512020-10-11 10:47:43 -0500184
185static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
186{
187}
YiFei Zhuf9d480b2020-10-11 10:47:42 -0500188#endif /* SECCOMP_ARCH_NATIVE */
189
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500190/**
191 * struct seccomp_filter - container for seccomp BPF programs
192 *
Christian Braunerb707dde2020-05-31 13:50:28 +0200193 * @refs: Reference count to manage the object lifetime.
194 * A filter's reference count is incremented for each directly
195 * attached task, once for the dependent filter, and if
196 * requested for the user notifier. When @refs reaches zero,
197 * the filter can be freed.
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200198 * @users: A filter's @users count is incremented for each directly
199 * attached task (filter installation, fork(), thread_sync),
200 * and once for the dependent filter (tracked in filter->prev).
201 * When it reaches zero it indicates that no direct or indirect
202 * users of that filter exist. No new tasks can get associated with
203 * this filter after reaching 0. The @users count is always smaller
204 * or equal to @refs. Hence, reaching 0 for @users does not mean
205 * the filter can be freed.
YiFei Zhu8e01b512020-10-11 10:47:43 -0500206 * @cache: cache of arch/syscall mappings to actions
Tyler Hickse66a3992017-08-11 04:33:56 +0000207 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -0700208 * @wait_killable_recv: Put notifying process in killable state once the
209 * notification is received by the userspace listener.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500210 * @prev: points to a previously installed, or inherited, filter
Mickaël Salaün285fdfc2016-09-20 19:39:47 +0200211 * @prog: the BPF program to evaluate
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700212 * @notif: the struct that holds all notification related information
213 * @notify_lock: A lock for all notification-related accesses.
Christian Brauner76194c42020-06-01 11:50:07 -0700214 * @wqh: A wait queue for poll if a notifier is in use.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500215 *
216 * seccomp_filter objects are organized in a tree linked via the @prev
217 * pointer. For any task, it appears to be a singly-linked list starting
218 * with current->seccomp.filter, the most recently attached or inherited filter.
219 * However, multiple filters may share a @prev node, by way of fork(), which
220 * results in a unidirectional tree existing in memory. This is similar to
221 * how namespaces work.
222 *
223 * seccomp_filter objects should never be modified after being attached
Christian Braunerb707dde2020-05-31 13:50:28 +0200224 * to a task_struct (other than @refs).
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500225 */
226struct seccomp_filter {
Christian Braunerb707dde2020-05-31 13:50:28 +0200227 refcount_t refs;
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200228 refcount_t users;
Tyler Hickse66a3992017-08-11 04:33:56 +0000229 bool log;
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -0700230 bool wait_killable_recv;
YiFei Zhu8e01b512020-10-11 10:47:43 -0500231 struct action_cache cache;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500232 struct seccomp_filter *prev;
Alexei Starovoitov7ae457c2014-07-30 20:34:16 -0700233 struct bpf_prog *prog;
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700234 struct notification *notif;
235 struct mutex notify_lock;
Christian Brauner76194c42020-06-01 11:50:07 -0700236 wait_queue_head_t wqh;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500237};
238
239/* Limit any path through the tree to 256KB worth of instructions. */
240#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
241
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100242/*
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500243 * Endianness is explicitly ignored and left for BPF program authors to manage
244 * as per the specific architecture.
245 */
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100246static void populate_seccomp_data(struct seccomp_data *sd)
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500247{
Denis Efremov2d9ca262020-08-24 15:59:21 +0300248 /*
249 * Instead of using current_pt_reg(), we're already doing the work
250 * to safely fetch "current", so just use "task" everywhere below.
251 */
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100252 struct task_struct *task = current;
253 struct pt_regs *regs = task_pt_regs(task);
Daniel Borkmann2eac7642014-04-14 21:02:59 +0200254 unsigned long args[6];
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500255
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100256 sd->nr = syscall_get_nr(task, regs);
Dmitry V. Levin16add412019-03-18 02:30:18 +0300257 sd->arch = syscall_get_arch(task);
Steven Rostedt (Red Hat)b35f5492016-11-07 16:26:37 -0500258 syscall_get_arguments(task, regs, args);
Daniel Borkmann2eac7642014-04-14 21:02:59 +0200259 sd->args[0] = args[0];
260 sd->args[1] = args[1];
261 sd->args[2] = args[2];
262 sd->args[3] = args[3];
263 sd->args[4] = args[4];
264 sd->args[5] = args[5];
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100265 sd->instruction_pointer = KSTK_EIP(task);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500266}
267
268/**
269 * seccomp_check_filter - verify seccomp filter code
270 * @filter: filter to verify
271 * @flen: length of filter
272 *
Alexei Starovoitov4df95ff2014-07-30 20:34:14 -0700273 * Takes a previously checked filter (by bpf_check_classic) and
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500274 * redirects all filter code that loads struct sk_buff data
275 * and related data through seccomp_bpf_load. It also
276 * enforces length and alignment checking of those loads.
277 *
278 * Returns 0 if the rule set is legal or -EINVAL if not.
279 */
280static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
281{
282 int pc;
283 for (pc = 0; pc < flen; pc++) {
284 struct sock_filter *ftest = &filter[pc];
285 u16 code = ftest->code;
286 u32 k = ftest->k;
287
288 switch (code) {
Daniel Borkmann34805932014-05-29 10:22:50 +0200289 case BPF_LD | BPF_W | BPF_ABS:
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100290 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500291 /* 32-bit aligned and not out of bounds. */
292 if (k >= sizeof(struct seccomp_data) || k & 3)
293 return -EINVAL;
294 continue;
Daniel Borkmann34805932014-05-29 10:22:50 +0200295 case BPF_LD | BPF_W | BPF_LEN:
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100296 ftest->code = BPF_LD | BPF_IMM;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500297 ftest->k = sizeof(struct seccomp_data);
298 continue;
Daniel Borkmann34805932014-05-29 10:22:50 +0200299 case BPF_LDX | BPF_W | BPF_LEN:
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100300 ftest->code = BPF_LDX | BPF_IMM;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500301 ftest->k = sizeof(struct seccomp_data);
302 continue;
303 /* Explicitly include allowed calls. */
Daniel Borkmann34805932014-05-29 10:22:50 +0200304 case BPF_RET | BPF_K:
305 case BPF_RET | BPF_A:
306 case BPF_ALU | BPF_ADD | BPF_K:
307 case BPF_ALU | BPF_ADD | BPF_X:
308 case BPF_ALU | BPF_SUB | BPF_K:
309 case BPF_ALU | BPF_SUB | BPF_X:
310 case BPF_ALU | BPF_MUL | BPF_K:
311 case BPF_ALU | BPF_MUL | BPF_X:
312 case BPF_ALU | BPF_DIV | BPF_K:
313 case BPF_ALU | BPF_DIV | BPF_X:
314 case BPF_ALU | BPF_AND | BPF_K:
315 case BPF_ALU | BPF_AND | BPF_X:
316 case BPF_ALU | BPF_OR | BPF_K:
317 case BPF_ALU | BPF_OR | BPF_X:
318 case BPF_ALU | BPF_XOR | BPF_K:
319 case BPF_ALU | BPF_XOR | BPF_X:
320 case BPF_ALU | BPF_LSH | BPF_K:
321 case BPF_ALU | BPF_LSH | BPF_X:
322 case BPF_ALU | BPF_RSH | BPF_K:
323 case BPF_ALU | BPF_RSH | BPF_X:
324 case BPF_ALU | BPF_NEG:
325 case BPF_LD | BPF_IMM:
326 case BPF_LDX | BPF_IMM:
327 case BPF_MISC | BPF_TAX:
328 case BPF_MISC | BPF_TXA:
329 case BPF_LD | BPF_MEM:
330 case BPF_LDX | BPF_MEM:
331 case BPF_ST:
332 case BPF_STX:
333 case BPF_JMP | BPF_JA:
334 case BPF_JMP | BPF_JEQ | BPF_K:
335 case BPF_JMP | BPF_JEQ | BPF_X:
336 case BPF_JMP | BPF_JGE | BPF_K:
337 case BPF_JMP | BPF_JGE | BPF_X:
338 case BPF_JMP | BPF_JGT | BPF_K:
339 case BPF_JMP | BPF_JGT | BPF_X:
340 case BPF_JMP | BPF_JSET | BPF_K:
341 case BPF_JMP | BPF_JSET | BPF_X:
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500342 continue;
343 default:
344 return -EINVAL;
345 }
346 }
347 return 0;
348}
349
YiFei Zhuf9d480b2020-10-11 10:47:42 -0500350#ifdef SECCOMP_ARCH_NATIVE
351static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
352 size_t bitmap_size,
353 int syscall_nr)
354{
355 if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
356 return false;
357 syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
358
359 return test_bit(syscall_nr, bitmap);
360}
361
362/**
363 * seccomp_cache_check_allow - lookup seccomp cache
364 * @sfilter: The seccomp filter
365 * @sd: The seccomp data to lookup the cache with
366 *
367 * Returns true if the seccomp_data is cached and allowed.
368 */
369static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
370 const struct seccomp_data *sd)
371{
372 int syscall_nr = sd->nr;
373 const struct action_cache *cache = &sfilter->cache;
374
375#ifndef SECCOMP_ARCH_COMPAT
376 /* A native-only architecture doesn't need to check sd->arch. */
377 return seccomp_cache_check_allow_bitmap(cache->allow_native,
378 SECCOMP_ARCH_NATIVE_NR,
379 syscall_nr);
380#else
381 if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
382 return seccomp_cache_check_allow_bitmap(cache->allow_native,
383 SECCOMP_ARCH_NATIVE_NR,
384 syscall_nr);
385 if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
386 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
387 SECCOMP_ARCH_COMPAT_NR,
388 syscall_nr);
389#endif /* SECCOMP_ARCH_COMPAT */
390
391 WARN_ON_ONCE(true);
392 return false;
393}
394#endif /* SECCOMP_ARCH_NATIVE */
395
Randy Dunlap0fb06242023-01-07 18:12:28 -0800396#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500397/**
Mickaël Salaün285fdfc2016-09-20 19:39:47 +0200398 * seccomp_run_filters - evaluates all seccomp filters against @sd
399 * @sd: optional seccomp data to be passed to filters
Kees Cookdeb4de82017-08-02 15:00:40 -0700400 * @match: stores struct seccomp_filter that resulted in the return value,
401 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
402 * be unchanged.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500403 *
404 * Returns valid seccomp BPF response codes.
405 */
Kees Cookdeb4de82017-08-02 15:00:40 -0700406static u32 seccomp_run_filters(const struct seccomp_data *sd,
407 struct seccomp_filter **match)
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500408{
Will Drewryacf3b2c2012-04-12 16:47:59 -0500409 u32 ret = SECCOMP_RET_ALLOW;
Pranith Kumar8225d382014-11-21 10:06:01 -0500410 /* Make sure cross-thread synced filter points somewhere sane. */
411 struct seccomp_filter *f =
Will Deacon506458e2017-10-24 11:22:48 +0100412 READ_ONCE(current->seccomp.filter);
Will Drewryacf3b2c2012-04-12 16:47:59 -0500413
414 /* Ensure unexpected behavior doesn't result in failing open. */
Igor Stoppa0d42d732018-09-05 23:34:43 +0300415 if (WARN_ON(f == NULL))
Kees Cook4d3b0b02017-08-11 13:01:39 -0700416 return SECCOMP_RET_KILL_PROCESS;
Will Drewryacf3b2c2012-04-12 16:47:59 -0500417
YiFei Zhuf9d480b2020-10-11 10:47:42 -0500418 if (seccomp_cache_check_allow(f, sd))
419 return SECCOMP_RET_ALLOW;
420
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500421 /*
422 * All filters in the list are evaluated and the lowest BPF return
Will Drewryacf3b2c2012-04-12 16:47:59 -0500423 * value always takes priority (ignoring the DATA).
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500424 */
Kees Cook3ba25302014-06-27 15:01:35 -0700425 for (; f; f = f->prev) {
David Miller3d9f773c2020-02-24 15:01:43 +0100426 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
Alexei Starovoitov8f577ca2014-05-13 19:50:47 -0700427
Kees Cook0466bdb2017-08-11 13:12:11 -0700428 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
Will Drewryacf3b2c2012-04-12 16:47:59 -0500429 ret = cur_ret;
Kees Cookdeb4de82017-08-02 15:00:40 -0700430 *match = f;
431 }
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500432 }
433 return ret;
434}
Kees Cook1f41b4502014-06-25 15:38:02 -0700435#endif /* CONFIG_SECCOMP_FILTER */
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500436
Kees Cook1f41b4502014-06-25 15:38:02 -0700437static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
438{
Guenter Roeck69f6a342014-08-10 20:50:30 -0700439 assert_spin_locked(&current->sighand->siglock);
Kees Cookdbd952122014-06-27 15:18:48 -0700440
Kees Cook1f41b4502014-06-25 15:38:02 -0700441 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
442 return false;
443
444 return true;
445}
446
Thomas Gleixner8bf37d82018-05-04 15:12:06 +0200447void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
Kees Cook5c307082018-05-01 15:07:31 -0700448
Kees Cook3ba25302014-06-27 15:01:35 -0700449static inline void seccomp_assign_mode(struct task_struct *task,
Kees Cook00a02d02018-05-03 14:56:12 -0700450 unsigned long seccomp_mode,
451 unsigned long flags)
Kees Cook1f41b4502014-06-25 15:38:02 -0700452{
Guenter Roeck69f6a342014-08-10 20:50:30 -0700453 assert_spin_locked(&task->sighand->siglock);
Kees Cookdbd952122014-06-27 15:18:48 -0700454
Kees Cook3ba25302014-06-27 15:01:35 -0700455 task->seccomp.mode = seccomp_mode;
456 /*
Gabriel Krisman Bertazi23d67a52020-11-16 12:42:00 -0500457 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
Kees Cook3ba25302014-06-27 15:01:35 -0700458 * filter) is set.
459 */
460 smp_mb__before_atomic();
Kees Cook00a02d02018-05-03 14:56:12 -0700461 /* Assume default seccomp processes want spec flaw mitigation. */
462 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
Thomas Gleixner8bf37d82018-05-04 15:12:06 +0200463 arch_seccomp_spec_mitigate(task);
Gabriel Krisman Bertazi23d67a52020-11-16 12:42:00 -0500464 set_task_syscall_work(task, SECCOMP);
Kees Cook1f41b4502014-06-25 15:38:02 -0700465}
466
467#ifdef CONFIG_SECCOMP_FILTER
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700468/* Returns 1 if the parent is an ancestor of the child. */
469static int is_ancestor(struct seccomp_filter *parent,
470 struct seccomp_filter *child)
471{
472 /* NULL is the root ancestor. */
473 if (parent == NULL)
474 return 1;
475 for (; child; child = child->prev)
476 if (child == parent)
477 return 1;
478 return 0;
479}
480
481/**
482 * seccomp_can_sync_threads: checks if all threads can be synchronized
483 *
484 * Expects sighand and cred_guard_mutex locks to be held.
485 *
486 * Returns 0 on success, -ve on error, or the pid of a thread which was
Tycho Andersen6beff002019-03-06 13:14:12 -0700487 * either not in the correct seccomp mode or did not have an ancestral
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700488 * seccomp filter.
489 */
490static inline pid_t seccomp_can_sync_threads(void)
491{
492 struct task_struct *thread, *caller;
493
494 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
Guenter Roeck69f6a342014-08-10 20:50:30 -0700495 assert_spin_locked(&current->sighand->siglock);
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700496
497 /* Validate all threads being eligible for synchronization. */
498 caller = current;
499 for_each_thread(caller, thread) {
500 pid_t failed;
501
502 /* Skip current, since it is initiating the sync. */
503 if (thread == caller)
504 continue;
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000505 /* Skip exited threads. */
506 if (thread->flags & PF_EXITING)
507 continue;
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700508
509 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
510 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
511 is_ancestor(thread->seccomp.filter,
512 caller->seccomp.filter)))
513 continue;
514
515 /* Return the first thread that cannot be synchronized. */
516 failed = task_pid_vnr(thread);
517 /* If the pid cannot be resolved, then return -ESRCH */
Igor Stoppa0d42d732018-09-05 23:34:43 +0300518 if (WARN_ON(failed == 0))
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700519 failed = -ESRCH;
520 return failed;
521 }
522
523 return 0;
524}
525
Christian Brauner3a15fb62020-05-31 13:50:29 +0200526static inline void seccomp_filter_free(struct seccomp_filter *filter)
527{
528 if (filter) {
529 bpf_prog_destroy(filter->prog);
530 kfree(filter);
531 }
532}
533
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200534static void __seccomp_filter_orphan(struct seccomp_filter *orig)
535{
536 while (orig && refcount_dec_and_test(&orig->users)) {
537 if (waitqueue_active(&orig->wqh))
538 wake_up_poll(&orig->wqh, EPOLLHUP);
539 orig = orig->prev;
540 }
541}
542
Christian Brauner3a15fb62020-05-31 13:50:29 +0200543static void __put_seccomp_filter(struct seccomp_filter *orig)
544{
545 /* Clean up single-reference branches iteratively. */
546 while (orig && refcount_dec_and_test(&orig->refs)) {
547 struct seccomp_filter *freeme = orig;
548 orig = orig->prev;
549 seccomp_filter_free(freeme);
550 }
551}
552
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200553static void __seccomp_filter_release(struct seccomp_filter *orig)
554{
555 /* Notify about any unused filters in the task's former filter tree. */
556 __seccomp_filter_orphan(orig);
557 /* Finally drop all references to the task's former tree. */
558 __put_seccomp_filter(orig);
559}
560
Christian Brauner3a15fb62020-05-31 13:50:29 +0200561/**
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200562 * seccomp_filter_release - Detach the task from its filter tree,
563 * drop its reference count, and notify
564 * about unused filters
Christian Brauner3a15fb62020-05-31 13:50:29 +0200565 *
Kees Cook46822862023-08-17 12:32:15 -0700566 * @tsk: task the filter should be released from.
567 *
Christian Brauner3a15fb62020-05-31 13:50:29 +0200568 * This function should only be called when the task is exiting as
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000569 * it detaches it from its filter tree. PF_EXITING has to be set
570 * for the task.
Christian Brauner3a15fb62020-05-31 13:50:29 +0200571 */
572void seccomp_filter_release(struct task_struct *tsk)
573{
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000574 struct seccomp_filter *orig;
Christian Brauner3a15fb62020-05-31 13:50:29 +0200575
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000576 if (WARN_ON((tsk->flags & PF_EXITING) == 0))
577 return;
YiFei Zhu0d8315d2020-11-11 07:33:54 -0600578
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000579 spin_lock_irq(&tsk->sighand->siglock);
580 orig = tsk->seccomp.filter;
Christian Brauner3a15fb62020-05-31 13:50:29 +0200581 /* Detach task from its filter tree. */
582 tsk->seccomp.filter = NULL;
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000583 spin_unlock_irq(&tsk->sighand->siglock);
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200584 __seccomp_filter_release(orig);
Christian Brauner3a15fb62020-05-31 13:50:29 +0200585}
586
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700587/**
588 * seccomp_sync_threads: sets all threads to use current's filter
589 *
Kees Cook46822862023-08-17 12:32:15 -0700590 * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
591 *
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700592 * Expects sighand and cred_guard_mutex locks to be held, and for
593 * seccomp_can_sync_threads() to have returned success already
594 * without dropping the locks.
595 *
596 */
Kees Cook00a02d02018-05-03 14:56:12 -0700597static inline void seccomp_sync_threads(unsigned long flags)
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700598{
599 struct task_struct *thread, *caller;
600
601 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
Guenter Roeck69f6a342014-08-10 20:50:30 -0700602 assert_spin_locked(&current->sighand->siglock);
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700603
604 /* Synchronize all threads. */
605 caller = current;
606 for_each_thread(caller, thread) {
607 /* Skip current, since it needs no changes. */
608 if (thread == caller)
609 continue;
610
Andrei Vaginbfafe5e2024-06-28 02:10:12 +0000611 /*
612 * Skip exited threads. seccomp_filter_release could have
613 * been already called for this task.
614 */
615 if (thread->flags & PF_EXITING)
616 continue;
617
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700618 /* Get a task reference for the new leaf node. */
619 get_seccomp_filter(caller);
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200620
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700621 /*
622 * Drop the task reference to the shared ancestor since
623 * current's path will hold a reference. (This also
624 * allows a put before the assignment.)
625 */
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200626 __seccomp_filter_release(thread->seccomp.filter);
627
628 /* Make our new filter tree visible. */
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700629 smp_store_release(&thread->seccomp.filter,
630 caller->seccomp.filter);
Kees Cookc818c032020-05-13 14:11:26 -0700631 atomic_set(&thread->seccomp.filter_count,
Hsuan-Chi Kuob4d8a582021-03-04 17:37:08 -0600632 atomic_read(&caller->seccomp.filter_count));
Jann Horn103502a2015-12-26 06:00:48 +0100633
634 /*
635 * Don't let an unprivileged task work around
636 * the no_new_privs restriction by creating
637 * a thread that sets it up, enters seccomp,
638 * then dies.
639 */
640 if (task_no_new_privs(caller))
641 task_set_no_new_privs(thread);
642
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700643 /*
644 * Opt the other thread into seccomp if needed.
645 * As threads are considered to be trust-realm
646 * equivalent (see ptrace_may_access), it is safe to
647 * allow one thread to transition the other.
648 */
Jann Horn103502a2015-12-26 06:00:48 +0100649 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
Kees Cook00a02d02018-05-03 14:56:12 -0700650 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
651 flags);
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700652 }
653}
654
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500655/**
Kees Cookc8bee432014-06-27 15:16:33 -0700656 * seccomp_prepare_filter: Prepares a seccomp filter for use.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500657 * @fprog: BPF program to install
658 *
Kees Cookc8bee432014-06-27 15:16:33 -0700659 * Returns filter on success or an ERR_PTR on failure.
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500660 */
Kees Cookc8bee432014-06-27 15:16:33 -0700661static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500662{
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200663 struct seccomp_filter *sfilter;
664 int ret;
YiFei Zhu8e01b512020-10-11 10:47:43 -0500665 const bool save_orig =
666#if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
667 true;
668#else
669 false;
670#endif
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500671
672 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
Kees Cookc8bee432014-06-27 15:16:33 -0700673 return ERR_PTR(-EINVAL);
Nicolas Schichand9e12f42e2015-05-06 16:12:28 +0200674
Kees Cookc8bee432014-06-27 15:16:33 -0700675 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500676
677 /*
Fabian Frederick119ce5c2014-06-06 14:37:53 -0700678 * Installing a seccomp filter requires that the task has
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500679 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
680 * This avoids scenarios where unprivileged tasks can affect the
681 * behavior of privileged children.
682 */
Kees Cook1d4457f2014-05-21 15:23:46 -0700683 if (!task_no_new_privs(current) &&
Mickaël Salaünfb145282020-10-30 13:38:49 +0100684 !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
Kees Cookc8bee432014-06-27 15:16:33 -0700685 return ERR_PTR(-EACCES);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500686
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100687 /* Allocate a new seccomp_filter */
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200688 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
689 if (!sfilter)
Nicolas Schichand9e12f42e2015-05-06 16:12:28 +0200690 return ERR_PTR(-ENOMEM);
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200691
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700692 mutex_init(&sfilter->notify_lock);
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200693 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
Tycho Andersenf8e529ed2015-10-27 09:23:59 +0900694 seccomp_check_filter, save_orig);
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200695 if (ret < 0) {
696 kfree(sfilter);
697 return ERR_PTR(ret);
Nicolas Schichand9e12f42e2015-05-06 16:12:28 +0200698 }
Alexei Starovoitovbd4cf0e2014-03-28 18:58:25 +0100699
Christian Braunerb707dde2020-05-31 13:50:28 +0200700 refcount_set(&sfilter->refs, 1);
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200701 refcount_set(&sfilter->users, 1);
Christian Brauner76194c42020-06-01 11:50:07 -0700702 init_waitqueue_head(&sfilter->wqh);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500703
Daniel Borkmannac67eb22015-05-06 16:12:30 +0200704 return sfilter;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500705}
706
707/**
Kees Cookc8bee432014-06-27 15:16:33 -0700708 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500709 * @user_filter: pointer to the user data containing a sock_fprog.
710 *
711 * Returns 0 on success and non-zero otherwise.
712 */
Kees Cookc8bee432014-06-27 15:16:33 -0700713static struct seccomp_filter *
714seccomp_prepare_user_filter(const char __user *user_filter)
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500715{
716 struct sock_fprog fprog;
Kees Cookc8bee432014-06-27 15:16:33 -0700717 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500718
719#ifdef CONFIG_COMPAT
Andy Lutomirski5c380652016-03-22 14:24:52 -0700720 if (in_compat_syscall()) {
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500721 struct compat_sock_fprog fprog32;
722 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
723 goto out;
724 fprog.len = fprog32.len;
725 fprog.filter = compat_ptr(fprog32.filter);
726 } else /* falls through to the if below. */
727#endif
728 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
729 goto out;
Kees Cookc8bee432014-06-27 15:16:33 -0700730 filter = seccomp_prepare_filter(&fprog);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500731out:
Kees Cookc8bee432014-06-27 15:16:33 -0700732 return filter;
733}
734
YiFei Zhu8e01b512020-10-11 10:47:43 -0500735#ifdef SECCOMP_ARCH_NATIVE
736/**
737 * seccomp_is_const_allow - check if filter is constant allow with given data
738 * @fprog: The BPF programs
739 * @sd: The seccomp data to check against, only syscall number and arch
740 * number are considered constant.
741 */
742static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
743 struct seccomp_data *sd)
744{
745 unsigned int reg_value = 0;
746 unsigned int pc;
747 bool op_res;
748
749 if (WARN_ON_ONCE(!fprog))
750 return false;
751
752 for (pc = 0; pc < fprog->len; pc++) {
753 struct sock_filter *insn = &fprog->filter[pc];
754 u16 code = insn->code;
755 u32 k = insn->k;
756
757 switch (code) {
758 case BPF_LD | BPF_W | BPF_ABS:
759 switch (k) {
760 case offsetof(struct seccomp_data, nr):
761 reg_value = sd->nr;
762 break;
763 case offsetof(struct seccomp_data, arch):
764 reg_value = sd->arch;
765 break;
766 default:
767 /* can't optimize (non-constant value load) */
768 return false;
769 }
770 break;
771 case BPF_RET | BPF_K:
772 /* reached return with constant values only, check allow */
773 return k == SECCOMP_RET_ALLOW;
774 case BPF_JMP | BPF_JA:
775 pc += insn->k;
776 break;
777 case BPF_JMP | BPF_JEQ | BPF_K:
778 case BPF_JMP | BPF_JGE | BPF_K:
779 case BPF_JMP | BPF_JGT | BPF_K:
780 case BPF_JMP | BPF_JSET | BPF_K:
781 switch (BPF_OP(code)) {
782 case BPF_JEQ:
783 op_res = reg_value == k;
784 break;
785 case BPF_JGE:
786 op_res = reg_value >= k;
787 break;
788 case BPF_JGT:
789 op_res = reg_value > k;
790 break;
791 case BPF_JSET:
792 op_res = !!(reg_value & k);
793 break;
794 default:
795 /* can't optimize (unknown jump) */
796 return false;
797 }
798
799 pc += op_res ? insn->jt : insn->jf;
800 break;
801 case BPF_ALU | BPF_AND | BPF_K:
802 reg_value &= k;
803 break;
804 default:
805 /* can't optimize (unknown insn) */
806 return false;
807 }
808 }
809
810 /* ran off the end of the filter?! */
811 WARN_ON(1);
812 return false;
813}
814
815static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
816 void *bitmap, const void *bitmap_prev,
817 size_t bitmap_size, int arch)
818{
819 struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
820 struct seccomp_data sd;
821 int nr;
822
823 if (bitmap_prev) {
824 /* The new filter must be as restrictive as the last. */
825 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
826 } else {
827 /* Before any filters, all syscalls are always allowed. */
828 bitmap_fill(bitmap, bitmap_size);
829 }
830
831 for (nr = 0; nr < bitmap_size; nr++) {
832 /* No bitmap change: not a cacheable action. */
833 if (!test_bit(nr, bitmap))
834 continue;
835
836 sd.nr = nr;
837 sd.arch = arch;
838
839 /* No bitmap change: continue to always allow. */
840 if (seccomp_is_const_allow(fprog, &sd))
841 continue;
842
843 /*
844 * Not a cacheable action: always run filters.
845 * atomic clear_bit() not needed, filter not visible yet.
846 */
847 __clear_bit(nr, bitmap);
848 }
849}
850
851/**
Cui GaoShenga3fc7122021-03-30 23:07:24 -0400852 * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
YiFei Zhu8e01b512020-10-11 10:47:43 -0500853 * @sfilter: The seccomp filter
854 *
855 * Returns 0 if successful or -errno if error occurred.
856 */
857static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
858{
859 struct action_cache *cache = &sfilter->cache;
860 const struct action_cache *cache_prev =
861 sfilter->prev ? &sfilter->prev->cache : NULL;
862
863 seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
864 cache_prev ? cache_prev->allow_native : NULL,
865 SECCOMP_ARCH_NATIVE_NR,
866 SECCOMP_ARCH_NATIVE);
867
868#ifdef SECCOMP_ARCH_COMPAT
869 seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
870 cache_prev ? cache_prev->allow_compat : NULL,
871 SECCOMP_ARCH_COMPAT_NR,
872 SECCOMP_ARCH_COMPAT);
873#endif /* SECCOMP_ARCH_COMPAT */
874}
875#endif /* SECCOMP_ARCH_NATIVE */
876
Kees Cookc8bee432014-06-27 15:16:33 -0700877/**
878 * seccomp_attach_filter: validate and attach filter
879 * @flags: flags to change filter behavior
880 * @filter: seccomp filter to add to the current process
881 *
Kees Cookdbd952122014-06-27 15:18:48 -0700882 * Caller must be holding current->sighand->siglock lock.
883 *
Tycho Andersen7a0df7f2019-03-06 13:14:13 -0700884 * Returns 0 on success, -ve on error, or
885 * - in TSYNC mode: the pid of a thread which was either not in the correct
886 * seccomp mode or did not have an ancestral seccomp filter
887 * - in NEW_LISTENER mode: the fd of the new listener
Kees Cookc8bee432014-06-27 15:16:33 -0700888 */
889static long seccomp_attach_filter(unsigned int flags,
890 struct seccomp_filter *filter)
891{
892 unsigned long total_insns;
893 struct seccomp_filter *walker;
894
Guenter Roeck69f6a342014-08-10 20:50:30 -0700895 assert_spin_locked(&current->sighand->siglock);
Kees Cookdbd952122014-06-27 15:18:48 -0700896
Kees Cookc8bee432014-06-27 15:16:33 -0700897 /* Validate resulting filter length. */
898 total_insns = filter->prog->len;
899 for (walker = current->seccomp.filter; walker; walker = walker->prev)
900 total_insns += walker->prog->len + 4; /* 4 instr penalty */
901 if (total_insns > MAX_INSNS_PER_PATH)
902 return -ENOMEM;
903
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700904 /* If thread sync has been requested, check that it is possible. */
905 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
906 int ret;
907
908 ret = seccomp_can_sync_threads();
Tycho Andersen51891492020-03-04 11:05:17 -0700909 if (ret) {
910 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
911 return -ESRCH;
912 else
913 return ret;
914 }
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700915 }
916
Tyler Hickse66a3992017-08-11 04:33:56 +0000917 /* Set log flag, if present. */
918 if (flags & SECCOMP_FILTER_FLAG_LOG)
919 filter->log = true;
920
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -0700921 /* Set wait killable flag, if present. */
922 if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
923 filter->wait_killable_recv = true;
924
Kees Cookc8bee432014-06-27 15:16:33 -0700925 /*
926 * If there is an existing filter, make it the prev and don't drop its
927 * task reference.
928 */
929 filter->prev = current->seccomp.filter;
YiFei Zhu8e01b512020-10-11 10:47:43 -0500930 seccomp_cache_prepare(filter);
Kees Cookc8bee432014-06-27 15:16:33 -0700931 current->seccomp.filter = filter;
Kees Cookc818c032020-05-13 14:11:26 -0700932 atomic_inc(&current->seccomp.filter_count);
Kees Cookc8bee432014-06-27 15:16:33 -0700933
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700934 /* Now that the new filter is in place, synchronize to all threads. */
935 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
Kees Cook00a02d02018-05-03 14:56:12 -0700936 seccomp_sync_threads(flags);
Kees Cookc2e1f2e2014-06-05 00:23:17 -0700937
Kees Cookc8bee432014-06-27 15:16:33 -0700938 return 0;
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500939}
940
Colin Ian King084f5602017-09-29 14:26:48 +0100941static void __get_seccomp_filter(struct seccomp_filter *filter)
Oleg Nesterov66a733e2017-09-27 09:25:30 -0600942{
Christian Braunerb707dde2020-05-31 13:50:28 +0200943 refcount_inc(&filter->refs);
Oleg Nesterov66a733e2017-09-27 09:25:30 -0600944}
945
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500946/* get_seccomp_filter - increments the reference count of the filter on @tsk */
947void get_seccomp_filter(struct task_struct *tsk)
948{
949 struct seccomp_filter *orig = tsk->seccomp.filter;
950 if (!orig)
951 return;
Oleg Nesterov66a733e2017-09-27 09:25:30 -0600952 __get_seccomp_filter(orig);
Christian Brauner99cdb8b2020-05-31 13:50:30 +0200953 refcount_inc(&orig->users);
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500954}
955
Will Drewrye2cfabdf2012-04-12 16:47:57 -0500956#endif /* CONFIG_SECCOMP_FILTER */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000958/* For use with seccomp_actions_logged */
Kees Cook4d3b0b02017-08-11 13:01:39 -0700959#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
960#define SECCOMP_LOG_KILL_THREAD (1 << 1)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000961#define SECCOMP_LOG_TRAP (1 << 2)
962#define SECCOMP_LOG_ERRNO (1 << 3)
963#define SECCOMP_LOG_TRACE (1 << 4)
Tyler Hicks59f5cf42017-08-11 04:33:57 +0000964#define SECCOMP_LOG_LOG (1 << 5)
965#define SECCOMP_LOG_ALLOW (1 << 6)
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700966#define SECCOMP_LOG_USER_NOTIF (1 << 7)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000967
Kees Cook4d3b0b02017-08-11 13:01:39 -0700968static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
969 SECCOMP_LOG_KILL_THREAD |
Kees Cookfd768752017-08-11 12:53:18 -0700970 SECCOMP_LOG_TRAP |
971 SECCOMP_LOG_ERRNO |
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700972 SECCOMP_LOG_USER_NOTIF |
Kees Cookfd768752017-08-11 12:53:18 -0700973 SECCOMP_LOG_TRACE |
Tyler Hicks59f5cf42017-08-11 04:33:57 +0000974 SECCOMP_LOG_LOG;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000975
Tyler Hickse66a3992017-08-11 04:33:56 +0000976static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
977 bool requested)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000978{
979 bool log = false;
980
981 switch (action) {
982 case SECCOMP_RET_ALLOW:
Tyler Hickse66a3992017-08-11 04:33:56 +0000983 break;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000984 case SECCOMP_RET_TRAP:
Tyler Hickse66a3992017-08-11 04:33:56 +0000985 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
986 break;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000987 case SECCOMP_RET_ERRNO:
Tyler Hickse66a3992017-08-11 04:33:56 +0000988 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
989 break;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000990 case SECCOMP_RET_TRACE:
Tyler Hickse66a3992017-08-11 04:33:56 +0000991 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +0000992 break;
Tycho Andersen6a21cc52018-12-09 11:24:13 -0700993 case SECCOMP_RET_USER_NOTIF:
994 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
995 break;
Tyler Hicks59f5cf42017-08-11 04:33:57 +0000996 case SECCOMP_RET_LOG:
997 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
998 break;
Kees Cookfd768752017-08-11 12:53:18 -0700999 case SECCOMP_RET_KILL_THREAD:
Kees Cookfd768752017-08-11 12:53:18 -07001000 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
Kees Cook4d3b0b02017-08-11 13:01:39 -07001001 break;
1002 case SECCOMP_RET_KILL_PROCESS:
1003 default:
1004 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00001005 }
1006
1007 /*
Tyler Hicks326bee02018-05-04 01:08:15 +00001008 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1009 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1010 * any action from being logged by removing the action name from the
1011 * seccomp_actions_logged sysctl.
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00001012 */
Tyler Hicks326bee02018-05-04 01:08:15 +00001013 if (!log)
1014 return;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00001015
Tyler Hicks326bee02018-05-04 01:08:15 +00001016 audit_seccomp(syscall, signr, action);
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00001017}
1018
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019/*
1020 * Secure computing mode 1 allows only read/write/exit/sigreturn.
1021 * To be fully secure this must be combined with rlimit
1022 * to limit the stack allocations too.
1023 */
Matt Redfearncb4253a2016-03-29 09:35:34 +01001024static const int mode1_syscalls[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
Kees Cookfe4bfff82020-06-19 12:20:15 -07001026 -1, /* negative terminated */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027};
1028
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001029static void __secure_computing_strict(int this_syscall)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030{
Kees Cookfe4bfff82020-06-19 12:20:15 -07001031 const int *allowed_syscalls = mode1_syscalls;
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001032#ifdef CONFIG_COMPAT
Andy Lutomirski5c380652016-03-22 14:24:52 -07001033 if (in_compat_syscall())
Kees Cookfe4bfff82020-06-19 12:20:15 -07001034 allowed_syscalls = get_compat_mode1_syscalls();
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001035#endif
1036 do {
Kees Cookfe4bfff82020-06-19 12:20:15 -07001037 if (*allowed_syscalls == this_syscall)
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001038 return;
Kees Cookfe4bfff82020-06-19 12:20:15 -07001039 } while (*++allowed_syscalls != -1);
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001040
1041#ifdef SECCOMP_DEBUG
1042 dump_stack();
1043#endif
Kees Cook495ac302022-02-07 20:21:13 -08001044 current->seccomp.mode = SECCOMP_MODE_DEAD;
Kees Cookfd768752017-08-11 12:53:18 -07001045 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001046 do_exit(SIGKILL);
1047}
1048
1049#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1050void secure_computing_strict(int this_syscall)
1051{
1052 int mode = current->seccomp.mode;
1053
Masahiro Yamada97f26452016-08-03 13:45:50 -07001054 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
Tycho Andersen13c4a902015-06-13 09:02:48 -06001055 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1056 return;
1057
Kees Cook221272f2015-06-15 15:29:16 -07001058 if (mode == SECCOMP_MODE_DISABLED)
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001059 return;
1060 else if (mode == SECCOMP_MODE_STRICT)
1061 __secure_computing_strict(this_syscall);
1062 else
1063 BUG();
1064}
1065#else
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001066
1067#ifdef CONFIG_SECCOMP_FILTER
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001068static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1069{
1070 /*
1071 * Note: overflow is ok here, the id just needs to be unique per
1072 * filter.
1073 */
1074 lockdep_assert_held(&filter->notify_lock);
1075 return filter->notif->next_id++;
1076}
1077
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001078static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001079{
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001080 int fd;
1081
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001082 /*
1083 * Remove the notification, and reset the list pointers, indicating
1084 * that it has been handled.
1085 */
1086 list_del_init(&addfd->list);
Christoph Hellwig42eb0d52021-03-25 09:22:09 +01001087 if (!addfd->setfd)
Christian Brauner4e94ddf2023-11-30 13:49:11 +01001088 fd = receive_fd(addfd->file, NULL, addfd->flags);
Christoph Hellwig42eb0d52021-03-25 09:22:09 +01001089 else
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001090 fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1091 addfd->ret = fd;
1092
1093 if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1094 /* If we fail reset and return an error to the notifier */
1095 if (fd < 0) {
1096 n->state = SECCOMP_NOTIFY_SENT;
1097 } else {
1098 /* Return the FD we just added */
1099 n->flags = 0;
1100 n->error = 0;
1101 n->val = fd;
1102 }
1103 }
1104
1105 /*
1106 * Mark the notification as completed. From this point, addfd mem
1107 * might be invalidated and we can't safely read it anymore.
1108 */
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001109 complete(&addfd->completion);
1110}
1111
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001112static bool should_sleep_killable(struct seccomp_filter *match,
1113 struct seccomp_knotif *n)
1114{
1115 return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
1116}
1117
Christian Braunerfb3c53862019-09-20 10:30:05 +02001118static int seccomp_do_user_notification(int this_syscall,
1119 struct seccomp_filter *match,
1120 const struct seccomp_data *sd)
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001121{
1122 int err;
Christian Braunerfb3c53862019-09-20 10:30:05 +02001123 u32 flags = 0;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001124 long ret = 0;
1125 struct seccomp_knotif n = {};
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001126 struct seccomp_kaddfd *addfd, *tmp;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001127
1128 mutex_lock(&match->notify_lock);
1129 err = -ENOSYS;
1130 if (!match->notif)
1131 goto out;
1132
1133 n.task = current;
1134 n.state = SECCOMP_NOTIFY_INIT;
1135 n.data = sd;
1136 n.id = seccomp_next_notify_id(match);
1137 init_completion(&n.ready);
Sargun Dhillon4cbf6f62022-04-27 18:54:46 -07001138 list_add_tail(&n.list, &match->notif->notifications);
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001139 INIT_LIST_HEAD(&n.addfd);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001140
Andrei Vagin4943b662023-03-07 23:31:56 -08001141 atomic_inc(&match->notif->requests);
Andrei Vagin48a10842023-03-07 23:31:59 -08001142 if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1143 wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM);
1144 else
1145 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001146
1147 /*
1148 * This is where we wait for a reply from userspace.
1149 */
Sargun Dhillonddc47392021-05-17 12:39:06 -07001150 do {
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001151 bool wait_killable = should_sleep_killable(match, &n);
1152
Sargun Dhillonddc47392021-05-17 12:39:06 -07001153 mutex_unlock(&match->notify_lock);
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001154 if (wait_killable)
1155 err = wait_for_completion_killable(&n.ready);
1156 else
1157 err = wait_for_completion_interruptible(&n.ready);
Sargun Dhillonddc47392021-05-17 12:39:06 -07001158 mutex_lock(&match->notify_lock);
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001159
1160 if (err != 0) {
1161 /*
1162 * Check to see if the notifcation got picked up and
1163 * whether we should switch to wait killable.
1164 */
1165 if (!wait_killable && should_sleep_killable(match, &n))
1166 continue;
1167
Sargun Dhillonddc47392021-05-17 12:39:06 -07001168 goto interrupted;
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001169 }
Sargun Dhillonddc47392021-05-17 12:39:06 -07001170
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001171 addfd = list_first_entry_or_null(&n.addfd,
1172 struct seccomp_kaddfd, list);
Sargun Dhillonddc47392021-05-17 12:39:06 -07001173 /* Check if we were woken up by a addfd message */
1174 if (addfd)
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001175 seccomp_handle_addfd(addfd, &n);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001176
Sargun Dhillonddc47392021-05-17 12:39:06 -07001177 } while (n.state != SECCOMP_NOTIFY_REPLIED);
1178
1179 ret = n.val;
1180 err = n.error;
1181 flags = n.flags;
1182
1183interrupted:
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001184 /* If there were any pending addfd calls, clear them out */
1185 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1186 /* The process went away before we got a chance to handle it */
1187 addfd->ret = -ESRCH;
1188 list_del_init(&addfd->list);
1189 complete(&addfd->completion);
1190 }
1191
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001192 /*
1193 * Note that it's possible the listener died in between the time when
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001194 * we were notified of a response (or a signal) and when we were able to
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001195 * re-acquire the lock, so only delete from the list if the
1196 * notification actually exists.
1197 *
1198 * Also note that this test is only valid because there's no way to
1199 * *reattach* to a notifier right now. If one is added, we'll need to
1200 * keep track of the notif itself and make sure they match here.
1201 */
1202 if (match->notif)
1203 list_del(&n.list);
1204out:
1205 mutex_unlock(&match->notify_lock);
Christian Braunerfb3c53862019-09-20 10:30:05 +02001206
1207 /* Userspace requests to continue the syscall. */
1208 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1209 return 0;
1210
Denis Efremov2d9ca262020-08-24 15:59:21 +03001211 syscall_set_return_value(current, current_pt_regs(),
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001212 err, ret);
Christian Braunerfb3c53862019-09-20 10:30:05 +02001213 return -1;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001214}
1215
Kees Cookce6526e2016-06-01 19:29:15 -07001216static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1217 const bool recheck_after_trace)
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001218{
1219 u32 filter_ret, action;
Kees Cookdeb4de82017-08-02 15:00:40 -07001220 struct seccomp_filter *match = NULL;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001221 int data;
Tycho Andersendb511392018-12-09 11:24:11 -07001222 struct seccomp_data sd_local;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223
Kees Cook3ba25302014-06-27 15:01:35 -07001224 /*
1225 * Make sure that any changes to mode from another thread have
Gabriel Krisman Bertazi23d67a52020-11-16 12:42:00 -05001226 * been seen after SYSCALL_WORK_SECCOMP was seen.
Kees Cook3ba25302014-06-27 15:01:35 -07001227 */
wanghongzhea381b702021-02-05 11:34:09 +08001228 smp_rmb();
Kees Cook3ba25302014-06-27 15:01:35 -07001229
Tycho Andersendb511392018-12-09 11:24:11 -07001230 if (!sd) {
1231 populate_seccomp_data(&sd_local);
1232 sd = &sd_local;
1233 }
1234
Kees Cookdeb4de82017-08-02 15:00:40 -07001235 filter_ret = seccomp_run_filters(sd, &match);
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001236 data = filter_ret & SECCOMP_RET_DATA;
Kees Cook0466bdb2017-08-11 13:12:11 -07001237 action = filter_ret & SECCOMP_RET_ACTION_FULL;
Andy Lutomirski87b526d2012-10-01 11:40:45 -07001238
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001239 switch (action) {
1240 case SECCOMP_RET_ERRNO:
Kees Cook580c57f2015-02-17 13:48:00 -08001241 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1242 if (data > MAX_ERRNO)
1243 data = MAX_ERRNO;
Denis Efremov2d9ca262020-08-24 15:59:21 +03001244 syscall_set_return_value(current, current_pt_regs(),
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001245 -data, 0);
1246 goto skip;
1247
1248 case SECCOMP_RET_TRAP:
1249 /* Show the handler the original registers. */
Denis Efremov2d9ca262020-08-24 15:59:21 +03001250 syscall_rollback(current, current_pt_regs());
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001251 /* Let the filter pass back 16 bits of data. */
Eric W. Biederman307d5222021-06-23 16:44:32 -05001252 force_sig_seccomp(this_syscall, data, false);
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001253 goto skip;
1254
1255 case SECCOMP_RET_TRACE:
Kees Cookce6526e2016-06-01 19:29:15 -07001256 /* We've been put in this state by the ptracer already. */
1257 if (recheck_after_trace)
1258 return 0;
1259
Kees Cook8112c4f2016-06-01 16:02:17 -07001260 /* ENOSYS these calls if there is no tracer attached. */
1261 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1262 syscall_set_return_value(current,
Denis Efremov2d9ca262020-08-24 15:59:21 +03001263 current_pt_regs(),
Kees Cook8112c4f2016-06-01 16:02:17 -07001264 -ENOSYS, 0);
1265 goto skip;
1266 }
1267
1268 /* Allow the BPF to provide the event message */
1269 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1270 /*
1271 * The delivery of a fatal signal during event
Kees Cook485a2522016-08-10 16:28:09 -07001272 * notification may silently skip tracer notification,
1273 * which could leave us with a potentially unmodified
1274 * syscall that the tracer would have liked to have
1275 * changed. Since the process is about to die, we just
1276 * force the syscall to be skipped and let the signal
1277 * kill the process and correctly handle any tracer exit
1278 * notifications.
Kees Cook8112c4f2016-06-01 16:02:17 -07001279 */
1280 if (fatal_signal_pending(current))
Kees Cook485a2522016-08-10 16:28:09 -07001281 goto skip;
Kees Cook8112c4f2016-06-01 16:02:17 -07001282 /* Check if the tracer forced the syscall to be skipped. */
Denis Efremov2d9ca262020-08-24 15:59:21 +03001283 this_syscall = syscall_get_nr(current, current_pt_regs());
Kees Cook8112c4f2016-06-01 16:02:17 -07001284 if (this_syscall < 0)
1285 goto skip;
1286
Kees Cookce6526e2016-06-01 19:29:15 -07001287 /*
1288 * Recheck the syscall, since it may have changed. This
1289 * intentionally uses a NULL struct seccomp_data to force
1290 * a reload of all registers. This does not goto skip since
1291 * a skip would have already been reported.
1292 */
1293 if (__seccomp_filter(this_syscall, NULL, true))
1294 return -1;
1295
Kees Cook8112c4f2016-06-01 16:02:17 -07001296 return 0;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001297
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001298 case SECCOMP_RET_USER_NOTIF:
Christian Braunerfb3c53862019-09-20 10:30:05 +02001299 if (seccomp_do_user_notification(this_syscall, match, sd))
1300 goto skip;
1301
1302 return 0;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001303
Tyler Hicks59f5cf42017-08-11 04:33:57 +00001304 case SECCOMP_RET_LOG:
1305 seccomp_log(this_syscall, 0, action, true);
1306 return 0;
1307
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001308 case SECCOMP_RET_ALLOW:
Kees Cookdeb4de82017-08-02 15:00:40 -07001309 /*
1310 * Note that the "match" filter will always be NULL for
1311 * this action since SECCOMP_RET_ALLOW is the starting
1312 * state in seccomp_run_filters().
1313 */
Kees Cook8112c4f2016-06-01 16:02:17 -07001314 return 0;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001315
Kees Cookfd768752017-08-11 12:53:18 -07001316 case SECCOMP_RET_KILL_THREAD:
Kees Cook4d3b0b02017-08-11 13:01:39 -07001317 case SECCOMP_RET_KILL_PROCESS:
Kees Cook131b6352017-02-23 09:24:24 -08001318 default:
Kees Cook495ac302022-02-07 20:21:13 -08001319 current->seccomp.mode = SECCOMP_MODE_DEAD;
Tyler Hickse66a3992017-08-11 04:33:56 +00001320 seccomp_log(this_syscall, SIGSYS, action, true);
Kees Cookd7276e32017-02-07 15:18:51 -08001321 /* Dump core only if this is the last remaining thread. */
Rich Felker4d671d92020-08-28 21:56:13 -04001322 if (action != SECCOMP_RET_KILL_THREAD ||
Eric W. Biedermand21918e2021-06-23 16:51:49 -05001323 (atomic_read(&current->signal->live) == 1)) {
Kees Cookd7276e32017-02-07 15:18:51 -08001324 /* Show the original registers in the dump. */
Denis Efremov2d9ca262020-08-24 15:59:21 +03001325 syscall_rollback(current, current_pt_regs());
Eric W. Biederman307d5222021-06-23 16:44:32 -05001326 /* Trigger a coredump with SIGSYS */
1327 force_sig_seccomp(this_syscall, data, true);
1328 } else {
Kees Cook4d3b0b02017-08-11 13:01:39 -07001329 do_exit(SIGSYS);
Eric W. Biederman307d5222021-06-23 16:44:32 -05001330 }
1331 return -1; /* skip the syscall go directly to signal handling */
Will Drewry8156b452012-04-17 14:48:58 -05001332 }
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001333
1334 unreachable();
1335
1336skip:
Tyler Hickse66a3992017-08-11 04:33:56 +00001337 seccomp_log(this_syscall, 0, action, match ? match->log : false);
Kees Cook8112c4f2016-06-01 16:02:17 -07001338 return -1;
1339}
1340#else
Kees Cookce6526e2016-06-01 19:29:15 -07001341static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1342 const bool recheck_after_trace)
Kees Cook8112c4f2016-06-01 16:02:17 -07001343{
1344 BUG();
Paul Cercueil04b38d02021-01-11 17:28:39 +00001345
1346 return -1;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001347}
1348#endif
1349
Kees Cook8112c4f2016-06-01 16:02:17 -07001350int __secure_computing(const struct seccomp_data *sd)
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001351{
1352 int mode = current->seccomp.mode;
Kees Cook8112c4f2016-06-01 16:02:17 -07001353 int this_syscall;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001354
Masahiro Yamada97f26452016-08-03 13:45:50 -07001355 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
Tycho Andersen13c4a902015-06-13 09:02:48 -06001356 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
Kees Cook8112c4f2016-06-01 16:02:17 -07001357 return 0;
1358
1359 this_syscall = sd ? sd->nr :
Denis Efremov2d9ca262020-08-24 15:59:21 +03001360 syscall_get_nr(current, current_pt_regs());
Tycho Andersen13c4a902015-06-13 09:02:48 -06001361
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001362 switch (mode) {
1363 case SECCOMP_MODE_STRICT:
1364 __secure_computing_strict(this_syscall); /* may call do_exit */
Kees Cook8112c4f2016-06-01 16:02:17 -07001365 return 0;
Andy Lutomirski13aa72f2014-07-21 18:49:15 -07001366 case SECCOMP_MODE_FILTER:
Kees Cookce6526e2016-06-01 19:29:15 -07001367 return __seccomp_filter(this_syscall, sd, false);
Kees Cook495ac302022-02-07 20:21:13 -08001368 /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1369 case SECCOMP_MODE_DEAD:
1370 WARN_ON_ONCE(1);
1371 do_exit(SIGKILL);
1372 return -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 default:
1374 BUG();
1375 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376}
Andy Lutomirskia4412fc2014-07-21 18:49:14 -07001377#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07001378
1379long prctl_get_seccomp(void)
1380{
1381 return current->seccomp.mode;
1382}
1383
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001384/**
Kees Cook3b23dd12014-06-25 15:55:25 -07001385 * seccomp_set_mode_strict: internal function for setting strict seccomp
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001386 *
1387 * Once current->seccomp.mode is non-zero, it may not be changed.
1388 *
1389 * Returns 0 on success or -EINVAL on failure.
1390 */
Kees Cook3b23dd12014-06-25 15:55:25 -07001391static long seccomp_set_mode_strict(void)
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07001392{
Kees Cook3b23dd12014-06-25 15:55:25 -07001393 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001394 long ret = -EINVAL;
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07001395
Kees Cookdbd952122014-06-27 15:18:48 -07001396 spin_lock_irq(&current->sighand->siglock);
1397
Kees Cook1f41b4502014-06-25 15:38:02 -07001398 if (!seccomp_may_assign_mode(seccomp_mode))
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07001399 goto out;
1400
Andrea Arcangelicf99aba2007-07-15 23:41:33 -07001401#ifdef TIF_NOTSC
Kees Cook3b23dd12014-06-25 15:55:25 -07001402 disable_TSC();
Andrea Arcangelicf99aba2007-07-15 23:41:33 -07001403#endif
Kees Cook00a02d02018-05-03 14:56:12 -07001404 seccomp_assign_mode(current, seccomp_mode, 0);
Kees Cook3b23dd12014-06-25 15:55:25 -07001405 ret = 0;
1406
1407out:
Kees Cookdbd952122014-06-27 15:18:48 -07001408 spin_unlock_irq(&current->sighand->siglock);
Kees Cook3b23dd12014-06-25 15:55:25 -07001409
1410 return ret;
1411}
1412
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001413#ifdef CONFIG_SECCOMP_FILTER
Tycho Andersene8393172020-09-02 08:09:53 -06001414static void seccomp_notify_free(struct seccomp_filter *filter)
1415{
1416 kfree(filter->notif);
1417 filter->notif = NULL;
1418}
1419
Tycho Andersena566a902020-09-01 19:40:16 -06001420static void seccomp_notify_detach(struct seccomp_filter *filter)
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001421{
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001422 struct seccomp_knotif *knotif;
1423
Tycho Andersena811dc62019-01-12 11:24:20 -07001424 if (!filter)
Tycho Andersena566a902020-09-01 19:40:16 -06001425 return;
Tycho Andersena811dc62019-01-12 11:24:20 -07001426
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001427 mutex_lock(&filter->notify_lock);
1428
1429 /*
1430 * If this file is being closed because e.g. the task who owned it
1431 * died, let's wake everyone up who was waiting on us.
1432 */
1433 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1434 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1435 continue;
1436
1437 knotif->state = SECCOMP_NOTIFY_REPLIED;
1438 knotif->error = -ENOSYS;
1439 knotif->val = 0;
1440
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001441 /*
1442 * We do not need to wake up any pending addfd messages, as
1443 * the notifier will do that for us, as this just looks
1444 * like a standard reply.
1445 */
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001446 complete(&knotif->ready);
1447 }
1448
Tycho Andersene8393172020-09-02 08:09:53 -06001449 seccomp_notify_free(filter);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001450 mutex_unlock(&filter->notify_lock);
Tycho Andersena566a902020-09-01 19:40:16 -06001451}
1452
1453static int seccomp_notify_release(struct inode *inode, struct file *file)
1454{
1455 struct seccomp_filter *filter = file->private_data;
1456
1457 seccomp_notify_detach(filter);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001458 __put_seccomp_filter(filter);
1459 return 0;
1460}
1461
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001462/* must be called with notif_lock held */
1463static inline struct seccomp_knotif *
1464find_notification(struct seccomp_filter *filter, u64 id)
1465{
1466 struct seccomp_knotif *cur;
1467
1468 lockdep_assert_held(&filter->notify_lock);
1469
1470 list_for_each_entry(cur, &filter->notif->notifications, list) {
1471 if (cur->id == id)
1472 return cur;
1473 }
1474
1475 return NULL;
1476}
1477
Andrei Vagin4943b662023-03-07 23:31:56 -08001478static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
1479 void *key)
1480{
1481 /* Avoid a wakeup if event not interesting for us. */
Andrei Vagin95036a72024-06-28 02:10:11 +00001482 if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP)))
Andrei Vagin4943b662023-03-07 23:31:56 -08001483 return 0;
1484 return autoremove_wake_function(wait, mode, sync, key);
1485}
1486
1487static int recv_wait_event(struct seccomp_filter *filter)
1488{
1489 DEFINE_WAIT_FUNC(wait, recv_wake_function);
1490 int ret;
1491
Andrei Vagin95036a72024-06-28 02:10:11 +00001492 if (refcount_read(&filter->users) == 0)
1493 return 0;
1494
Andrei Vagin4943b662023-03-07 23:31:56 -08001495 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1496 return 0;
1497
1498 for (;;) {
1499 ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
1500
1501 if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1502 break;
Andrei Vagin95036a72024-06-28 02:10:11 +00001503 if (refcount_read(&filter->users) == 0)
1504 break;
Andrei Vagin4943b662023-03-07 23:31:56 -08001505
1506 if (ret)
1507 return ret;
1508
1509 schedule();
1510 }
1511 finish_wait(&filter->wqh, &wait);
1512 return 0;
1513}
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001514
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001515static long seccomp_notify_recv(struct seccomp_filter *filter,
1516 void __user *buf)
1517{
1518 struct seccomp_knotif *knotif = NULL, *cur;
1519 struct seccomp_notif unotif;
1520 ssize_t ret;
1521
Sargun Dhillon2882d532019-12-28 22:24:50 -08001522 /* Verify that we're not given garbage to keep struct extensible. */
1523 ret = check_zeroed_user(buf, sizeof(unotif));
1524 if (ret < 0)
1525 return ret;
1526 if (!ret)
1527 return -EINVAL;
1528
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001529 memset(&unotif, 0, sizeof(unotif));
1530
Andrei Vagin4943b662023-03-07 23:31:56 -08001531 ret = recv_wait_event(filter);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001532 if (ret < 0)
1533 return ret;
1534
1535 mutex_lock(&filter->notify_lock);
1536 list_for_each_entry(cur, &filter->notif->notifications, list) {
1537 if (cur->state == SECCOMP_NOTIFY_INIT) {
1538 knotif = cur;
1539 break;
1540 }
1541 }
1542
1543 /*
1544 * If we didn't find a notification, it could be that the task was
1545 * interrupted by a fatal signal between the time we were woken and
1546 * when we were able to acquire the rw lock.
1547 */
1548 if (!knotif) {
1549 ret = -ENOENT;
1550 goto out;
1551 }
1552
1553 unotif.id = knotif->id;
1554 unotif.pid = task_pid_vnr(knotif->task);
1555 unotif.data = *(knotif->data);
1556
1557 knotif->state = SECCOMP_NOTIFY_SENT;
Christian Brauner76194c42020-06-01 11:50:07 -07001558 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001559 ret = 0;
1560out:
1561 mutex_unlock(&filter->notify_lock);
1562
1563 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1564 ret = -EFAULT;
1565
1566 /*
1567 * Userspace screwed up. To make sure that we keep this
1568 * notification alive, let's reset it back to INIT. It
1569 * may have died when we released the lock, so we need to make
1570 * sure it's still around.
1571 */
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001572 mutex_lock(&filter->notify_lock);
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001573 knotif = find_notification(filter, unotif.id);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001574 if (knotif) {
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001575 /* Reset the process to make sure it's not stuck */
1576 if (should_sleep_killable(filter, knotif))
1577 complete(&knotif->ready);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001578 knotif->state = SECCOMP_NOTIFY_INIT;
Andrei Vagin4943b662023-03-07 23:31:56 -08001579 atomic_inc(&filter->notif->requests);
1580 wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001581 }
1582 mutex_unlock(&filter->notify_lock);
1583 }
1584
1585 return ret;
1586}
1587
1588static long seccomp_notify_send(struct seccomp_filter *filter,
1589 void __user *buf)
1590{
1591 struct seccomp_notif_resp resp = {};
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001592 struct seccomp_knotif *knotif;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001593 long ret;
1594
1595 if (copy_from_user(&resp, buf, sizeof(resp)))
1596 return -EFAULT;
1597
Christian Braunerfb3c53862019-09-20 10:30:05 +02001598 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1599 return -EINVAL;
1600
1601 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1602 (resp.error || resp.val))
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001603 return -EINVAL;
1604
1605 ret = mutex_lock_interruptible(&filter->notify_lock);
1606 if (ret < 0)
1607 return ret;
1608
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001609 knotif = find_notification(filter, resp.id);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001610 if (!knotif) {
1611 ret = -ENOENT;
1612 goto out;
1613 }
1614
1615 /* Allow exactly one reply. */
1616 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1617 ret = -EINPROGRESS;
1618 goto out;
1619 }
1620
1621 ret = 0;
1622 knotif->state = SECCOMP_NOTIFY_REPLIED;
1623 knotif->error = resp.error;
1624 knotif->val = resp.val;
Christian Braunerfb3c53862019-09-20 10:30:05 +02001625 knotif->flags = resp.flags;
Andrei Vagin48a10842023-03-07 23:31:59 -08001626 if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1627 complete_on_current_cpu(&knotif->ready);
1628 else
1629 complete(&knotif->ready);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001630out:
1631 mutex_unlock(&filter->notify_lock);
1632 return ret;
1633}
1634
1635static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1636 void __user *buf)
1637{
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001638 struct seccomp_knotif *knotif;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001639 u64 id;
1640 long ret;
1641
1642 if (copy_from_user(&id, buf, sizeof(id)))
1643 return -EFAULT;
1644
1645 ret = mutex_lock_interruptible(&filter->notify_lock);
1646 if (ret < 0)
1647 return ret;
1648
Sargun Dhillon9f87dcf2020-06-01 04:25:32 -07001649 knotif = find_notification(filter, id);
1650 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1651 ret = 0;
1652 else
1653 ret = -ENOENT;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001654
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001655 mutex_unlock(&filter->notify_lock);
1656 return ret;
1657}
1658
Andrei Vagin48a10842023-03-07 23:31:59 -08001659static long seccomp_notify_set_flags(struct seccomp_filter *filter,
1660 unsigned long flags)
1661{
1662 long ret;
1663
1664 if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1665 return -EINVAL;
1666
1667 ret = mutex_lock_interruptible(&filter->notify_lock);
1668 if (ret < 0)
1669 return ret;
1670 filter->notif->flags = flags;
1671 mutex_unlock(&filter->notify_lock);
1672 return 0;
1673}
1674
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001675static long seccomp_notify_addfd(struct seccomp_filter *filter,
1676 struct seccomp_notif_addfd __user *uaddfd,
1677 unsigned int size)
1678{
1679 struct seccomp_notif_addfd addfd;
1680 struct seccomp_knotif *knotif;
1681 struct seccomp_kaddfd kaddfd;
1682 int ret;
1683
1684 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1685 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1686
1687 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1688 return -EINVAL;
1689
1690 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1691 if (ret)
1692 return ret;
1693
1694 if (addfd.newfd_flags & ~O_CLOEXEC)
1695 return -EINVAL;
1696
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001697 if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001698 return -EINVAL;
1699
1700 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1701 return -EINVAL;
1702
1703 kaddfd.file = fget(addfd.srcfd);
1704 if (!kaddfd.file)
1705 return -EBADF;
1706
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001707 kaddfd.ioctl_flags = addfd.flags;
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001708 kaddfd.flags = addfd.newfd_flags;
Christoph Hellwig42eb0d52021-03-25 09:22:09 +01001709 kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1710 kaddfd.fd = addfd.newfd;
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001711 init_completion(&kaddfd.completion);
1712
1713 ret = mutex_lock_interruptible(&filter->notify_lock);
1714 if (ret < 0)
1715 goto out;
1716
1717 knotif = find_notification(filter, addfd.id);
1718 if (!knotif) {
1719 ret = -ENOENT;
1720 goto out_unlock;
1721 }
1722
1723 /*
1724 * We do not want to allow for FD injection to occur before the
1725 * notification has been picked up by a userspace handler, or after
1726 * the notification has been replied to.
1727 */
1728 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1729 ret = -EINPROGRESS;
1730 goto out_unlock;
1731 }
1732
Rodrigo Campos0ae71c72021-05-17 12:39:07 -07001733 if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1734 /*
1735 * Disallow queuing an atomic addfd + send reply while there are
1736 * some addfd requests still to process.
1737 *
1738 * There is no clear reason to support it and allows us to keep
1739 * the loop on the other side straight-forward.
1740 */
1741 if (!list_empty(&knotif->addfd)) {
1742 ret = -EBUSY;
1743 goto out_unlock;
1744 }
1745
1746 /* Allow exactly only one reply */
1747 knotif->state = SECCOMP_NOTIFY_REPLIED;
1748 }
1749
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001750 list_add(&kaddfd.list, &knotif->addfd);
1751 complete(&knotif->ready);
1752 mutex_unlock(&filter->notify_lock);
1753
1754 /* Now we wait for it to be processed or be interrupted */
1755 ret = wait_for_completion_interruptible(&kaddfd.completion);
1756 if (ret == 0) {
1757 /*
1758 * We had a successful completion. The other side has already
1759 * removed us from the addfd queue, and
1760 * wait_for_completion_interruptible has a memory barrier upon
1761 * success that lets us read this value directly without
1762 * locking.
1763 */
1764 ret = kaddfd.ret;
1765 goto out;
1766 }
1767
1768 mutex_lock(&filter->notify_lock);
1769 /*
1770 * Even though we were woken up by a signal and not a successful
1771 * completion, a completion may have happened in the mean time.
1772 *
1773 * We need to check again if the addfd request has been handled,
1774 * and if not, we will remove it from the queue.
1775 */
1776 if (list_empty(&kaddfd.list))
1777 ret = kaddfd.ret;
1778 else
1779 list_del(&kaddfd.list);
1780
1781out_unlock:
1782 mutex_unlock(&filter->notify_lock);
1783out:
1784 fput(kaddfd.file);
1785
1786 return ret;
1787}
1788
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001789static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1790 unsigned long arg)
1791{
1792 struct seccomp_filter *filter = file->private_data;
1793 void __user *buf = (void __user *)arg;
1794
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001795 /* Fixed-size ioctls */
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001796 switch (cmd) {
1797 case SECCOMP_IOCTL_NOTIF_RECV:
1798 return seccomp_notify_recv(filter, buf);
1799 case SECCOMP_IOCTL_NOTIF_SEND:
1800 return seccomp_notify_send(filter, buf);
Kees Cook47e33c052020-06-15 15:42:46 -07001801 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001802 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1803 return seccomp_notify_id_valid(filter, buf);
Andrei Vagin48a10842023-03-07 23:31:59 -08001804 case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
1805 return seccomp_notify_set_flags(filter, arg);
Sargun Dhillon7cf97b12020-06-02 18:10:43 -07001806 }
1807
1808 /* Extensible Argument ioctls */
1809#define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1810 switch (EA_IOCTL(cmd)) {
1811 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1812 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001813 default:
1814 return -EINVAL;
1815 }
1816}
1817
1818static __poll_t seccomp_notify_poll(struct file *file,
1819 struct poll_table_struct *poll_tab)
1820{
1821 struct seccomp_filter *filter = file->private_data;
1822 __poll_t ret = 0;
1823 struct seccomp_knotif *cur;
1824
Christian Brauner76194c42020-06-01 11:50:07 -07001825 poll_wait(file, &filter->wqh, poll_tab);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001826
Tycho Andersen319deec2018-12-12 19:46:54 -07001827 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001828 return EPOLLERR;
1829
1830 list_for_each_entry(cur, &filter->notif->notifications, list) {
1831 if (cur->state == SECCOMP_NOTIFY_INIT)
1832 ret |= EPOLLIN | EPOLLRDNORM;
1833 if (cur->state == SECCOMP_NOTIFY_SENT)
1834 ret |= EPOLLOUT | EPOLLWRNORM;
1835 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1836 break;
1837 }
1838
1839 mutex_unlock(&filter->notify_lock);
1840
Christian Brauner99cdb8b2020-05-31 13:50:30 +02001841 if (refcount_read(&filter->users) == 0)
1842 ret |= EPOLLHUP;
1843
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001844 return ret;
1845}
1846
1847static const struct file_operations seccomp_notify_ops = {
1848 .poll = seccomp_notify_poll,
1849 .release = seccomp_notify_release,
1850 .unlocked_ioctl = seccomp_notify_ioctl,
Sven Schnelle3db81af2020-03-10 13:33:32 +01001851 .compat_ioctl = seccomp_notify_ioctl,
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001852};
1853
1854static struct file *init_listener(struct seccomp_filter *filter)
1855{
Jann Horndfe719f2020-10-05 03:44:01 +02001856 struct file *ret;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001857
1858 ret = ERR_PTR(-ENOMEM);
1859 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1860 if (!filter->notif)
1861 goto out;
1862
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001863 filter->notif->next_id = get_random_u64();
1864 INIT_LIST_HEAD(&filter->notif->notifications);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001865
1866 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1867 filter, O_RDWR);
1868 if (IS_ERR(ret))
1869 goto out_notif;
1870
1871 /* The file has a reference to it now */
1872 __get_seccomp_filter(filter);
1873
1874out_notif:
1875 if (IS_ERR(ret))
Tycho Andersene8393172020-09-02 08:09:53 -06001876 seccomp_notify_free(filter);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001877out:
1878 return ret;
1879}
1880
Jann Horndfe719f2020-10-05 03:44:01 +02001881/*
1882 * Does @new_child have a listener while an ancestor also has a listener?
1883 * If so, we'll want to reject this filter.
1884 * This only has to be tested for the current process, even in the TSYNC case,
1885 * because TSYNC installs @child with the same parent on all threads.
1886 * Note that @new_child is not hooked up to its parent at this point yet, so
1887 * we use current->seccomp.filter.
1888 */
1889static bool has_duplicate_listener(struct seccomp_filter *new_child)
1890{
1891 struct seccomp_filter *cur;
1892
1893 /* must be protected against concurrent TSYNC */
1894 lockdep_assert_held(&current->sighand->siglock);
1895
1896 if (!new_child->notif)
1897 return false;
1898 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1899 if (cur->notif)
1900 return true;
1901 }
1902
1903 return false;
1904}
1905
Kees Cook3b23dd12014-06-25 15:55:25 -07001906/**
1907 * seccomp_set_mode_filter: internal function for setting seccomp filter
Kees Cook48dc92b2014-06-25 16:08:24 -07001908 * @flags: flags to change filter behavior
Kees Cook3b23dd12014-06-25 15:55:25 -07001909 * @filter: struct sock_fprog containing filter
1910 *
1911 * This function may be called repeatedly to install additional filters.
1912 * Every filter successfully installed will be evaluated (in reverse order)
1913 * for each system call the task makes.
1914 *
1915 * Once current->seccomp.mode is non-zero, it may not be changed.
1916 *
1917 * Returns 0 on success or -EINVAL on failure.
1918 */
Kees Cook48dc92b2014-06-25 16:08:24 -07001919static long seccomp_set_mode_filter(unsigned int flags,
1920 const char __user *filter)
Kees Cook3b23dd12014-06-25 15:55:25 -07001921{
1922 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
Kees Cookc8bee432014-06-27 15:16:33 -07001923 struct seccomp_filter *prepared = NULL;
Kees Cook3b23dd12014-06-25 15:55:25 -07001924 long ret = -EINVAL;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001925 int listener = -1;
1926 struct file *listener_f = NULL;
Kees Cook3b23dd12014-06-25 15:55:25 -07001927
Kees Cook48dc92b2014-06-25 16:08:24 -07001928 /* Validate flags. */
Kees Cookc2e1f2e2014-06-05 00:23:17 -07001929 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
Kees Cookdbd952122014-06-27 15:18:48 -07001930 return -EINVAL;
Kees Cook48dc92b2014-06-25 16:08:24 -07001931
Tycho Andersen7a0df7f2019-03-06 13:14:13 -07001932 /*
1933 * In the successful case, NEW_LISTENER returns the new listener fd.
1934 * But in the failure case, TSYNC returns the thread that died. If you
1935 * combine these two flags, there's no way to tell whether something
Tycho Andersen51891492020-03-04 11:05:17 -07001936 * succeeded or failed. So, let's disallow this combination if the user
1937 * has not explicitly requested no errors from TSYNC.
Tycho Andersen7a0df7f2019-03-06 13:14:13 -07001938 */
1939 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
Tycho Andersen51891492020-03-04 11:05:17 -07001940 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1941 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
Tycho Andersen7a0df7f2019-03-06 13:14:13 -07001942 return -EINVAL;
1943
Sargun Dhillonc2aa2df2022-05-03 01:09:56 -07001944 /*
1945 * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1946 * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1947 */
1948 if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1949 ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1950 return -EINVAL;
1951
Kees Cookc8bee432014-06-27 15:16:33 -07001952 /* Prepare the new filter before holding any locks. */
1953 prepared = seccomp_prepare_user_filter(filter);
1954 if (IS_ERR(prepared))
1955 return PTR_ERR(prepared);
1956
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001957 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1958 listener = get_unused_fd_flags(O_CLOEXEC);
1959 if (listener < 0) {
1960 ret = listener;
1961 goto out_free;
1962 }
1963
1964 listener_f = init_listener(prepared);
1965 if (IS_ERR(listener_f)) {
1966 put_unused_fd(listener);
1967 ret = PTR_ERR(listener_f);
1968 goto out_free;
1969 }
1970 }
1971
Kees Cookc2e1f2e2014-06-05 00:23:17 -07001972 /*
1973 * Make sure we cannot change seccomp or nnp state via TSYNC
1974 * while another thread is in the middle of calling exec.
1975 */
1976 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1977 mutex_lock_killable(&current->signal->cred_guard_mutex))
Tycho Andersen6a21cc52018-12-09 11:24:13 -07001978 goto out_put_fd;
Kees Cookc2e1f2e2014-06-05 00:23:17 -07001979
Kees Cookdbd952122014-06-27 15:18:48 -07001980 spin_lock_irq(&current->sighand->siglock);
1981
Kees Cook3b23dd12014-06-25 15:55:25 -07001982 if (!seccomp_may_assign_mode(seccomp_mode))
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001983 goto out;
Kees Cook3b23dd12014-06-25 15:55:25 -07001984
Jann Horndfe719f2020-10-05 03:44:01 +02001985 if (has_duplicate_listener(prepared)) {
1986 ret = -EBUSY;
1987 goto out;
1988 }
1989
Kees Cookc8bee432014-06-27 15:16:33 -07001990 ret = seccomp_attach_filter(flags, prepared);
Kees Cook3b23dd12014-06-25 15:55:25 -07001991 if (ret)
1992 goto out;
Kees Cookc8bee432014-06-27 15:16:33 -07001993 /* Do not free the successfully attached filter. */
1994 prepared = NULL;
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07001995
Kees Cook00a02d02018-05-03 14:56:12 -07001996 seccomp_assign_mode(current, seccomp_mode, flags);
Will Drewrye2cfabdf2012-04-12 16:47:57 -05001997out:
Kees Cookdbd952122014-06-27 15:18:48 -07001998 spin_unlock_irq(&current->sighand->siglock);
Kees Cookc2e1f2e2014-06-05 00:23:17 -07001999 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
2000 mutex_unlock(&current->signal->cred_guard_mutex);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002001out_put_fd:
2002 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
Tycho Andersen7a0df7f2019-03-06 13:14:13 -07002003 if (ret) {
Tycho Andersena811dc62019-01-12 11:24:20 -07002004 listener_f->private_data = NULL;
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002005 fput(listener_f);
2006 put_unused_fd(listener);
Tycho Andersena566a902020-09-01 19:40:16 -06002007 seccomp_notify_detach(prepared);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002008 } else {
2009 fd_install(listener, listener_f);
2010 ret = listener;
2011 }
2012 }
Kees Cookc2e1f2e2014-06-05 00:23:17 -07002013out_free:
Kees Cookc8bee432014-06-27 15:16:33 -07002014 seccomp_filter_free(prepared);
Andrea Arcangeli1d9d02f2007-07-15 23:41:32 -07002015 return ret;
2016}
Kees Cook3b23dd12014-06-25 15:55:25 -07002017#else
Kees Cook48dc92b2014-06-25 16:08:24 -07002018static inline long seccomp_set_mode_filter(unsigned int flags,
2019 const char __user *filter)
Kees Cook3b23dd12014-06-25 15:55:25 -07002020{
2021 return -EINVAL;
2022}
2023#endif
Kees Cookd78ab022014-05-21 15:02:11 -07002024
Tyler Hicksd612b1f2017-08-11 04:33:53 +00002025static long seccomp_get_action_avail(const char __user *uaction)
2026{
2027 u32 action;
2028
2029 if (copy_from_user(&action, uaction, sizeof(action)))
2030 return -EFAULT;
2031
2032 switch (action) {
Kees Cook0466bdb2017-08-11 13:12:11 -07002033 case SECCOMP_RET_KILL_PROCESS:
Kees Cookfd768752017-08-11 12:53:18 -07002034 case SECCOMP_RET_KILL_THREAD:
Tyler Hicksd612b1f2017-08-11 04:33:53 +00002035 case SECCOMP_RET_TRAP:
2036 case SECCOMP_RET_ERRNO:
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002037 case SECCOMP_RET_USER_NOTIF:
Tyler Hicksd612b1f2017-08-11 04:33:53 +00002038 case SECCOMP_RET_TRACE:
Tyler Hicks59f5cf42017-08-11 04:33:57 +00002039 case SECCOMP_RET_LOG:
Tyler Hicksd612b1f2017-08-11 04:33:53 +00002040 case SECCOMP_RET_ALLOW:
2041 break;
2042 default:
2043 return -EOPNOTSUPP;
2044 }
2045
2046 return 0;
2047}
2048
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002049static long seccomp_get_notif_sizes(void __user *usizes)
2050{
2051 struct seccomp_notif_sizes sizes = {
2052 .seccomp_notif = sizeof(struct seccomp_notif),
2053 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
2054 .seccomp_data = sizeof(struct seccomp_data),
2055 };
2056
2057 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
2058 return -EFAULT;
2059
2060 return 0;
2061}
2062
Kees Cook48dc92b2014-06-25 16:08:24 -07002063/* Common entry point for both prctl and syscall. */
2064static long do_seccomp(unsigned int op, unsigned int flags,
Tycho Andersena5662e42018-12-09 11:24:12 -07002065 void __user *uargs)
Kees Cook48dc92b2014-06-25 16:08:24 -07002066{
2067 switch (op) {
2068 case SECCOMP_SET_MODE_STRICT:
2069 if (flags != 0 || uargs != NULL)
2070 return -EINVAL;
2071 return seccomp_set_mode_strict();
2072 case SECCOMP_SET_MODE_FILTER:
2073 return seccomp_set_mode_filter(flags, uargs);
Tyler Hicksd612b1f2017-08-11 04:33:53 +00002074 case SECCOMP_GET_ACTION_AVAIL:
2075 if (flags != 0)
2076 return -EINVAL;
2077
2078 return seccomp_get_action_avail(uargs);
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002079 case SECCOMP_GET_NOTIF_SIZES:
2080 if (flags != 0)
2081 return -EINVAL;
2082
2083 return seccomp_get_notif_sizes(uargs);
Kees Cook48dc92b2014-06-25 16:08:24 -07002084 default:
2085 return -EINVAL;
2086 }
2087}
2088
2089SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
Tycho Andersena5662e42018-12-09 11:24:12 -07002090 void __user *, uargs)
Kees Cook48dc92b2014-06-25 16:08:24 -07002091{
2092 return do_seccomp(op, flags, uargs);
2093}
2094
Kees Cookd78ab022014-05-21 15:02:11 -07002095/**
2096 * prctl_set_seccomp: configures current->seccomp.mode
2097 * @seccomp_mode: requested mode to use
2098 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2099 *
2100 * Returns 0 on success or -EINVAL on failure.
2101 */
Tycho Andersena5662e42018-12-09 11:24:12 -07002102long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
Kees Cookd78ab022014-05-21 15:02:11 -07002103{
Kees Cook48dc92b2014-06-25 16:08:24 -07002104 unsigned int op;
Tycho Andersena5662e42018-12-09 11:24:12 -07002105 void __user *uargs;
Kees Cook48dc92b2014-06-25 16:08:24 -07002106
Kees Cook3b23dd12014-06-25 15:55:25 -07002107 switch (seccomp_mode) {
2108 case SECCOMP_MODE_STRICT:
Kees Cook48dc92b2014-06-25 16:08:24 -07002109 op = SECCOMP_SET_MODE_STRICT;
2110 /*
2111 * Setting strict mode through prctl always ignored filter,
2112 * so make sure it is always NULL here to pass the internal
2113 * check in do_seccomp().
2114 */
2115 uargs = NULL;
2116 break;
Kees Cook3b23dd12014-06-25 15:55:25 -07002117 case SECCOMP_MODE_FILTER:
Kees Cook48dc92b2014-06-25 16:08:24 -07002118 op = SECCOMP_SET_MODE_FILTER;
2119 uargs = filter;
2120 break;
Kees Cook3b23dd12014-06-25 15:55:25 -07002121 default:
2122 return -EINVAL;
2123 }
Kees Cook48dc92b2014-06-25 16:08:24 -07002124
2125 /* prctl interface doesn't have flags, so they are always zero. */
2126 return do_seccomp(op, 0, uargs);
Kees Cookd78ab022014-05-21 15:02:11 -07002127}
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002128
2129#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
Tycho Andersenf06eae82017-10-11 09:39:20 -06002130static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2131 unsigned long filter_off)
2132{
2133 struct seccomp_filter *orig, *filter;
2134 unsigned long count;
2135
2136 /*
2137 * Note: this is only correct because the caller should be the (ptrace)
2138 * tracer of the task, otherwise lock_task_sighand is needed.
2139 */
2140 spin_lock_irq(&task->sighand->siglock);
2141
2142 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2143 spin_unlock_irq(&task->sighand->siglock);
2144 return ERR_PTR(-EINVAL);
2145 }
2146
2147 orig = task->seccomp.filter;
2148 __get_seccomp_filter(orig);
2149 spin_unlock_irq(&task->sighand->siglock);
2150
2151 count = 0;
2152 for (filter = orig; filter; filter = filter->prev)
2153 count++;
2154
2155 if (filter_off >= count) {
2156 filter = ERR_PTR(-ENOENT);
2157 goto out;
2158 }
2159
2160 count -= filter_off;
2161 for (filter = orig; filter && count > 1; filter = filter->prev)
2162 count--;
2163
2164 if (WARN_ON(count != 1 || !filter)) {
2165 filter = ERR_PTR(-ENOENT);
2166 goto out;
2167 }
2168
2169 __get_seccomp_filter(filter);
2170
2171out:
2172 __put_seccomp_filter(orig);
2173 return filter;
2174}
2175
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002176long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2177 void __user *data)
2178{
2179 struct seccomp_filter *filter;
2180 struct sock_fprog_kern *fprog;
2181 long ret;
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002182
2183 if (!capable(CAP_SYS_ADMIN) ||
2184 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2185 return -EACCES;
2186 }
2187
Tycho Andersenf06eae82017-10-11 09:39:20 -06002188 filter = get_nth_filter(task, filter_off);
2189 if (IS_ERR(filter))
2190 return PTR_ERR(filter);
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002191
2192 fprog = filter->prog->orig_prog;
2193 if (!fprog) {
Mickaël Salaün470bf1f2016-03-24 02:46:33 +01002194 /* This must be a new non-cBPF filter, since we save
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002195 * every cBPF filter's orig_prog above when
2196 * CONFIG_CHECKPOINT_RESTORE is enabled.
2197 */
2198 ret = -EMEDIUMTYPE;
2199 goto out;
2200 }
2201
2202 ret = fprog->len;
2203 if (!data)
2204 goto out;
2205
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002206 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2207 ret = -EFAULT;
2208
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002209out:
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002210 __put_seccomp_filter(filter);
2211 return ret;
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002212}
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002213
Tycho Andersen26500472017-10-11 09:39:21 -06002214long seccomp_get_metadata(struct task_struct *task,
2215 unsigned long size, void __user *data)
2216{
2217 long ret;
2218 struct seccomp_filter *filter;
2219 struct seccomp_metadata kmd = {};
2220
2221 if (!capable(CAP_SYS_ADMIN) ||
2222 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2223 return -EACCES;
2224 }
2225
2226 size = min_t(unsigned long, size, sizeof(kmd));
2227
Tycho Andersen63bb0042018-02-20 19:47:46 -07002228 if (size < sizeof(kmd.filter_off))
2229 return -EINVAL;
2230
2231 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
Tycho Andersen26500472017-10-11 09:39:21 -06002232 return -EFAULT;
2233
2234 filter = get_nth_filter(task, kmd.filter_off);
2235 if (IS_ERR(filter))
2236 return PTR_ERR(filter);
2237
Tycho Andersen26500472017-10-11 09:39:21 -06002238 if (filter->log)
2239 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2240
2241 ret = size;
2242 if (copy_to_user(data, &kmd, size))
2243 ret = -EFAULT;
2244
2245 __put_seccomp_filter(filter);
Tycho Andersenf8e529ed2015-10-27 09:23:59 +09002246 return ret;
2247}
2248#endif
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002249
2250#ifdef CONFIG_SYSCTL
2251
2252/* Human readable action names for friendly sysctl interaction */
Kees Cook0466bdb2017-08-11 13:12:11 -07002253#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
Kees Cookfd768752017-08-11 12:53:18 -07002254#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002255#define SECCOMP_RET_TRAP_NAME "trap"
2256#define SECCOMP_RET_ERRNO_NAME "errno"
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002257#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002258#define SECCOMP_RET_TRACE_NAME "trace"
Tyler Hicks59f5cf42017-08-11 04:33:57 +00002259#define SECCOMP_RET_LOG_NAME "log"
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002260#define SECCOMP_RET_ALLOW_NAME "allow"
2261
Kees Cookfd768752017-08-11 12:53:18 -07002262static const char seccomp_actions_avail[] =
Kees Cook0466bdb2017-08-11 13:12:11 -07002263 SECCOMP_RET_KILL_PROCESS_NAME " "
Kees Cookfd768752017-08-11 12:53:18 -07002264 SECCOMP_RET_KILL_THREAD_NAME " "
2265 SECCOMP_RET_TRAP_NAME " "
2266 SECCOMP_RET_ERRNO_NAME " "
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002267 SECCOMP_RET_USER_NOTIF_NAME " "
Kees Cookfd768752017-08-11 12:53:18 -07002268 SECCOMP_RET_TRACE_NAME " "
2269 SECCOMP_RET_LOG_NAME " "
2270 SECCOMP_RET_ALLOW_NAME;
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002271
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002272struct seccomp_log_name {
2273 u32 log;
2274 const char *name;
2275};
2276
2277static const struct seccomp_log_name seccomp_log_names[] = {
Kees Cook0466bdb2017-08-11 13:12:11 -07002278 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
Kees Cookfd768752017-08-11 12:53:18 -07002279 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002280 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2281 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
Tycho Andersen6a21cc52018-12-09 11:24:13 -07002282 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002283 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
Tyler Hicks59f5cf42017-08-11 04:33:57 +00002284 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002285 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2286 { }
2287};
2288
2289static bool seccomp_names_from_actions_logged(char *names, size_t size,
Tyler Hicksbeb44ac2018-05-04 01:08:13 +00002290 u32 actions_logged,
2291 const char *sep)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002292{
2293 const struct seccomp_log_name *cur;
Tyler Hicksbeb44ac2018-05-04 01:08:13 +00002294 bool append_sep = false;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002295
2296 for (cur = seccomp_log_names; cur->name && size; cur++) {
2297 ssize_t ret;
2298
2299 if (!(actions_logged & cur->log))
2300 continue;
2301
Tyler Hicksbeb44ac2018-05-04 01:08:13 +00002302 if (append_sep) {
2303 ret = strscpy(names, sep, size);
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002304 if (ret < 0)
2305 return false;
2306
2307 names += ret;
2308 size -= ret;
2309 } else
Tyler Hicksbeb44ac2018-05-04 01:08:13 +00002310 append_sep = true;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002311
2312 ret = strscpy(names, cur->name, size);
2313 if (ret < 0)
2314 return false;
2315
2316 names += ret;
2317 size -= ret;
2318 }
2319
2320 return true;
2321}
2322
2323static bool seccomp_action_logged_from_name(u32 *action_logged,
2324 const char *name)
2325{
2326 const struct seccomp_log_name *cur;
2327
2328 for (cur = seccomp_log_names; cur->name; cur++) {
2329 if (!strcmp(cur->name, name)) {
2330 *action_logged = cur->log;
2331 return true;
2332 }
2333 }
2334
2335 return false;
2336}
2337
2338static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2339{
2340 char *name;
2341
2342 *actions_logged = 0;
2343 while ((name = strsep(&names, " ")) && *name) {
2344 u32 action_logged = 0;
2345
2346 if (!seccomp_action_logged_from_name(&action_logged, name))
2347 return false;
2348
2349 *actions_logged |= action_logged;
2350 }
2351
2352 return true;
2353}
2354
Kees Cooke4067372024-05-08 10:13:41 -07002355static int read_actions_logged(const struct ctl_table *ro_table, void *buffer,
Tyler Hicksd013db02018-05-04 01:08:12 +00002356 size_t *lenp, loff_t *ppos)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002357{
2358 char names[sizeof(seccomp_actions_avail)];
2359 struct ctl_table table;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002360
2361 memset(names, 0, sizeof(names));
2362
Tyler Hicksd013db02018-05-04 01:08:12 +00002363 if (!seccomp_names_from_actions_logged(names, sizeof(names),
Tyler Hicksbeb44ac2018-05-04 01:08:13 +00002364 seccomp_actions_logged, " "))
Tyler Hicksd013db02018-05-04 01:08:12 +00002365 return -EINVAL;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002366
2367 table = *ro_table;
2368 table.data = names;
2369 table.maxlen = sizeof(names);
Tyler Hicksd013db02018-05-04 01:08:12 +00002370 return proc_dostring(&table, 0, buffer, lenp, ppos);
2371}
2372
Kees Cooke4067372024-05-08 10:13:41 -07002373static int write_actions_logged(const struct ctl_table *ro_table, void *buffer,
Tyler Hicksea6eca72018-05-04 01:08:14 +00002374 size_t *lenp, loff_t *ppos, u32 *actions_logged)
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002375{
2376 char names[sizeof(seccomp_actions_avail)];
2377 struct ctl_table table;
2378 int ret;
2379
Tyler Hicksd013db02018-05-04 01:08:12 +00002380 if (!capable(CAP_SYS_ADMIN))
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002381 return -EPERM;
2382
2383 memset(names, 0, sizeof(names));
2384
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002385 table = *ro_table;
2386 table.data = names;
2387 table.maxlen = sizeof(names);
Tyler Hicksd013db02018-05-04 01:08:12 +00002388 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002389 if (ret)
2390 return ret;
2391
Tyler Hicksea6eca72018-05-04 01:08:14 +00002392 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
Tyler Hicksd013db02018-05-04 01:08:12 +00002393 return -EINVAL;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002394
Tyler Hicksea6eca72018-05-04 01:08:14 +00002395 if (*actions_logged & SECCOMP_LOG_ALLOW)
Tyler Hicksd013db02018-05-04 01:08:12 +00002396 return -EINVAL;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002397
Tyler Hicksea6eca72018-05-04 01:08:14 +00002398 seccomp_actions_logged = *actions_logged;
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002399 return 0;
2400}
2401
Tyler Hicksea6eca72018-05-04 01:08:14 +00002402static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2403 int ret)
2404{
2405 char names[sizeof(seccomp_actions_avail)];
2406 char old_names[sizeof(seccomp_actions_avail)];
2407 const char *new = names;
2408 const char *old = old_names;
2409
2410 if (!audit_enabled)
2411 return;
2412
2413 memset(names, 0, sizeof(names));
2414 memset(old_names, 0, sizeof(old_names));
2415
2416 if (ret)
2417 new = "?";
2418 else if (!actions_logged)
2419 new = "(none)";
2420 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2421 actions_logged, ","))
2422 new = "?";
2423
2424 if (!old_actions_logged)
2425 old = "(none)";
2426 else if (!seccomp_names_from_actions_logged(old_names,
2427 sizeof(old_names),
2428 old_actions_logged, ","))
2429 old = "?";
2430
2431 return audit_seccomp_actions_logged(new, old, !ret);
2432}
2433
Joel Granados78eb4ea2024-07-24 20:59:29 +02002434static int seccomp_actions_logged_handler(const struct ctl_table *ro_table, int write,
Christoph Hellwig32927392020-04-24 08:43:38 +02002435 void *buffer, size_t *lenp,
Tyler Hicksd013db02018-05-04 01:08:12 +00002436 loff_t *ppos)
2437{
Tyler Hicksea6eca72018-05-04 01:08:14 +00002438 int ret;
2439
2440 if (write) {
2441 u32 actions_logged = 0;
2442 u32 old_actions_logged = seccomp_actions_logged;
2443
2444 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2445 &actions_logged);
2446 audit_actions_logged(actions_logged, old_actions_logged, ret);
2447 } else
2448 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2449
2450 return ret;
Tyler Hicksd013db02018-05-04 01:08:12 +00002451}
2452
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002453static struct ctl_table seccomp_sysctl_table[] = {
2454 {
2455 .procname = "actions_avail",
2456 .data = (void *) &seccomp_actions_avail,
2457 .maxlen = sizeof(seccomp_actions_avail),
2458 .mode = 0444,
2459 .proc_handler = proc_dostring,
2460 },
Tyler Hicks0ddec0f2017-08-11 04:33:54 +00002461 {
2462 .procname = "actions_logged",
2463 .mode = 0644,
2464 .proc_handler = seccomp_actions_logged_handler,
2465 },
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002466};
2467
2468static int __init seccomp_sysctl_init(void)
2469{
Luis Chamberlain02a6b452023-03-02 12:28:22 -08002470 register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
Tyler Hicks8e5f1ad2017-08-11 04:33:52 +00002471 return 0;
2472}
2473
2474device_initcall(seccomp_sysctl_init)
2475
2476#endif /* CONFIG_SYSCTL */
YiFei Zhu0d8315d2020-11-11 07:33:54 -06002477
2478#ifdef CONFIG_SECCOMP_CACHE_DEBUG
2479/* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2480static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2481 const void *bitmap, size_t bitmap_size)
2482{
2483 int nr;
2484
2485 for (nr = 0; nr < bitmap_size; nr++) {
2486 bool cached = test_bit(nr, bitmap);
2487 char *status = cached ? "ALLOW" : "FILTER";
2488
2489 seq_printf(m, "%s %d %s\n", name, nr, status);
2490 }
2491}
2492
2493int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2494 struct pid *pid, struct task_struct *task)
2495{
2496 struct seccomp_filter *f;
2497 unsigned long flags;
2498
2499 /*
2500 * We don't want some sandboxed process to know what their seccomp
2501 * filters consist of.
2502 */
2503 if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2504 return -EACCES;
2505
2506 if (!lock_task_sighand(task, &flags))
2507 return -ESRCH;
2508
2509 f = READ_ONCE(task->seccomp.filter);
2510 if (!f) {
2511 unlock_task_sighand(task, &flags);
2512 return 0;
2513 }
2514
2515 /* prevent filter from being freed while we are printing it */
2516 __get_seccomp_filter(f);
2517 unlock_task_sighand(task, &flags);
2518
2519 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2520 f->cache.allow_native,
2521 SECCOMP_ARCH_NATIVE_NR);
2522
2523#ifdef SECCOMP_ARCH_COMPAT
2524 proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2525 f->cache.allow_compat,
2526 SECCOMP_ARCH_COMPAT_NR);
2527#endif /* SECCOMP_ARCH_COMPAT */
2528
2529 __put_seccomp_filter(f);
2530 return 0;
2531}
2532#endif /* CONFIG_SECCOMP_CACHE_DEBUG */