Thomas Gleixner | b886d83c | 2019-06-01 10:08:55 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (C) 2007 |
| 4 | * |
| 5 | * Author: Eric Biederman <ebiederm@xmision.com> |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 6 | */ |
| 7 | |
Paul Gortmaker | 9984de1 | 2011-05-23 14:51:41 -0400 | [diff] [blame] | 8 | #include <linux/export.h> |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 9 | #include <linux/uts.h> |
| 10 | #include <linux/utsname.h> |
Jason A. Donenfeld | 37608ba | 2022-09-27 11:35:16 +0200 | [diff] [blame] | 11 | #include <linux/random.h> |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 12 | #include <linux/sysctl.h> |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 13 | #include <linux/wait.h> |
Ingo Molnar | cd9c513 | 2017-02-08 18:51:58 +0100 | [diff] [blame] | 14 | #include <linux/rwsem.h> |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 15 | |
Yuanhan Liu | cd89f46 | 2013-02-27 17:05:22 -0800 | [diff] [blame] | 16 | #ifdef CONFIG_PROC_SYSCTL |
| 17 | |
Jann Horn | 42a0cc3 | 2018-06-25 18:34:10 +0200 | [diff] [blame] | 18 | static void *get_uts(struct ctl_table *table) |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 19 | { |
| 20 | char *which = table->data; |
Pavel Emelyanov | 32df81c | 2007-11-28 16:21:38 -0800 | [diff] [blame] | 21 | struct uts_namespace *uts_ns; |
| 22 | |
| 23 | uts_ns = current->nsproxy->uts_ns; |
| 24 | which = (which - (char *)&init_uts_ns) + (char *)uts_ns; |
Cedric Le Goater | 7d69a1f | 2007-07-15 23:40:58 -0700 | [diff] [blame] | 25 | |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 26 | return which; |
| 27 | } |
| 28 | |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 29 | /* |
| 30 | * Special case of dostring for the UTS structure. This has locks |
| 31 | * to observe. Should this be in kernel/sys.c ???? |
| 32 | */ |
Joe Perches | 6f8fd1d | 2014-06-06 14:38:08 -0700 | [diff] [blame] | 33 | static int proc_do_uts_string(struct ctl_table *table, int write, |
Christoph Hellwig | 3292739 | 2020-04-24 08:43:38 +0200 | [diff] [blame] | 34 | void *buffer, size_t *lenp, loff_t *ppos) |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 35 | { |
| 36 | struct ctl_table uts_table; |
| 37 | int r; |
Jann Horn | 42a0cc3 | 2018-06-25 18:34:10 +0200 | [diff] [blame] | 38 | char tmp_data[__NEW_UTS_LEN + 1]; |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 39 | |
Jann Horn | 42a0cc3 | 2018-06-25 18:34:10 +0200 | [diff] [blame] | 40 | memcpy(&uts_table, table, sizeof(uts_table)); |
| 41 | uts_table.data = tmp_data; |
| 42 | |
| 43 | /* |
| 44 | * Buffer the value in tmp_data so that proc_dostring() can be called |
| 45 | * without holding any locks. |
| 46 | * We also need to read the original value in the write==1 case to |
| 47 | * support partial writes. |
| 48 | */ |
| 49 | down_read(&uts_sem); |
| 50 | memcpy(tmp_data, get_uts(table), sizeof(tmp_data)); |
| 51 | up_read(&uts_sem); |
| 52 | r = proc_dostring(&uts_table, write, buffer, lenp, ppos); |
| 53 | |
| 54 | if (write) { |
| 55 | /* |
| 56 | * Write back the new value. |
| 57 | * Note that, since we dropped uts_sem, the result can |
| 58 | * theoretically be incorrect if there are two parallel writes |
| 59 | * at non-zero offsets to the same sysctl. |
| 60 | */ |
Jason A. Donenfeld | 37608ba | 2022-09-27 11:35:16 +0200 | [diff] [blame] | 61 | add_device_randomness(tmp_data, sizeof(tmp_data)); |
Jann Horn | 42a0cc3 | 2018-06-25 18:34:10 +0200 | [diff] [blame] | 62 | down_write(&uts_sem); |
| 63 | memcpy(get_uts(table), tmp_data, sizeof(tmp_data)); |
| 64 | up_write(&uts_sem); |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 65 | proc_sys_poll_notify(table->poll); |
Jann Horn | 42a0cc3 | 2018-06-25 18:34:10 +0200 | [diff] [blame] | 66 | } |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 67 | |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 68 | return r; |
| 69 | } |
| 70 | #else |
| 71 | #define proc_do_uts_string NULL |
| 72 | #endif |
| 73 | |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 74 | static DEFINE_CTL_TABLE_POLL(hostname_poll); |
| 75 | static DEFINE_CTL_TABLE_POLL(domainname_poll); |
| 76 | |
Linus Torvalds | 52826d3 | 2022-10-23 12:01:01 -0700 | [diff] [blame] | 77 | // Note: update 'enum uts_proc' to match any changes to this table |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 78 | static struct ctl_table uts_kern_table[] = { |
| 79 | { |
Petr Vorel | bfca3dd | 2022-09-01 21:44:03 +0200 | [diff] [blame] | 80 | .procname = "arch", |
| 81 | .data = init_uts_ns.name.machine, |
| 82 | .maxlen = sizeof(init_uts_ns.name.machine), |
| 83 | .mode = 0444, |
| 84 | .proc_handler = proc_do_uts_string, |
| 85 | }, |
| 86 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 87 | .procname = "ostype", |
| 88 | .data = init_uts_ns.name.sysname, |
| 89 | .maxlen = sizeof(init_uts_ns.name.sysname), |
| 90 | .mode = 0444, |
| 91 | .proc_handler = proc_do_uts_string, |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 92 | }, |
| 93 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 94 | .procname = "osrelease", |
| 95 | .data = init_uts_ns.name.release, |
| 96 | .maxlen = sizeof(init_uts_ns.name.release), |
| 97 | .mode = 0444, |
| 98 | .proc_handler = proc_do_uts_string, |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 99 | }, |
| 100 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 101 | .procname = "version", |
| 102 | .data = init_uts_ns.name.version, |
| 103 | .maxlen = sizeof(init_uts_ns.name.version), |
| 104 | .mode = 0444, |
| 105 | .proc_handler = proc_do_uts_string, |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 106 | }, |
| 107 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 108 | .procname = "hostname", |
| 109 | .data = init_uts_ns.name.nodename, |
| 110 | .maxlen = sizeof(init_uts_ns.name.nodename), |
| 111 | .mode = 0644, |
| 112 | .proc_handler = proc_do_uts_string, |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 113 | .poll = &hostname_poll, |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 114 | }, |
| 115 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 116 | .procname = "domainname", |
| 117 | .data = init_uts_ns.name.domainname, |
| 118 | .maxlen = sizeof(init_uts_ns.name.domainname), |
| 119 | .mode = 0644, |
| 120 | .proc_handler = proc_do_uts_string, |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 121 | .poll = &domainname_poll, |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 122 | }, |
| 123 | {} |
| 124 | }; |
| 125 | |
| 126 | static struct ctl_table uts_root_table[] = { |
| 127 | { |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 128 | .procname = "kernel", |
| 129 | .mode = 0555, |
| 130 | .child = uts_kern_table, |
| 131 | }, |
| 132 | {} |
| 133 | }; |
| 134 | |
Lucas De Marchi | f1ecf06 | 2011-11-02 13:39:22 -0700 | [diff] [blame] | 135 | #ifdef CONFIG_PROC_SYSCTL |
| 136 | /* |
| 137 | * Notify userspace about a change in a certain entry of uts_kern_table, |
| 138 | * identified by the parameter proc. |
| 139 | */ |
| 140 | void uts_proc_notify(enum uts_proc proc) |
| 141 | { |
| 142 | struct ctl_table *table = &uts_kern_table[proc]; |
| 143 | |
| 144 | proc_sys_poll_notify(table->poll); |
| 145 | } |
| 146 | #endif |
| 147 | |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 148 | static int __init utsname_sysctl_init(void) |
| 149 | { |
Eric W. Biederman | 0b4d414 | 2007-02-14 00:34:09 -0800 | [diff] [blame] | 150 | register_sysctl_table(uts_root_table); |
Eric W. Biederman | 39732ac | 2007-02-14 00:33:58 -0800 | [diff] [blame] | 151 | return 0; |
| 152 | } |
| 153 | |
Fabian Frederick | 95583e4 | 2014-06-04 16:11:26 -0700 | [diff] [blame] | 154 | device_initcall(utsname_sysctl_init); |