| /* |
| * Creating audit events from TTY input. |
| * |
| * Copyright (C) 2007 Red Hat, Inc. All rights reserved. This copyrighted |
| * material is made available to anyone wishing to use, modify, copy, or |
| * redistribute it subject to the terms and conditions of the GNU General |
| * Public License v.2. |
| * |
| * Authors: Miloslav Trmac <mitr@redhat.com> |
| */ |
| |
| #include <linux/audit.h> |
| #include <linux/slab.h> |
| #include <linux/tty.h> |
| |
| struct tty_audit_buf { |
| struct mutex mutex; /* Protects all data below */ |
| dev_t dev; /* The TTY which the data is from */ |
| unsigned icanon:1; |
| size_t valid; |
| unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */ |
| }; |
| |
| static struct tty_audit_buf *tty_audit_buf_ref(void) |
| { |
| struct tty_audit_buf *buf; |
| |
| buf = current->signal->tty_audit_buf; |
| WARN_ON(buf == ERR_PTR(-ESRCH)); |
| return buf; |
| } |
| |
| static struct tty_audit_buf *tty_audit_buf_alloc(void) |
| { |
| struct tty_audit_buf *buf; |
| |
| buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
| if (!buf) |
| goto err; |
| buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
| if (!buf->data) |
| goto err_buf; |
| mutex_init(&buf->mutex); |
| buf->dev = MKDEV(0, 0); |
| buf->icanon = 0; |
| buf->valid = 0; |
| return buf; |
| |
| err_buf: |
| kfree(buf); |
| err: |
| return NULL; |
| } |
| |
| static void tty_audit_buf_free(struct tty_audit_buf *buf) |
| { |
| WARN_ON(buf->valid != 0); |
| kfree(buf->data); |
| kfree(buf); |
| } |
| |
| static void tty_audit_log(const char *description, dev_t dev, |
| unsigned char *data, size_t size) |
| { |
| struct audit_buffer *ab; |
| struct task_struct *tsk = current; |
| pid_t pid = task_pid_nr(tsk); |
| uid_t uid = from_kuid(&init_user_ns, task_uid(tsk)); |
| uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk)); |
| unsigned int sessionid = audit_get_sessionid(tsk); |
| |
| ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
| if (ab) { |
| char name[sizeof(tsk->comm)]; |
| |
| audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" |
| " minor=%d comm=", description, pid, uid, |
| loginuid, sessionid, MAJOR(dev), MINOR(dev)); |
| get_task_comm(name, tsk); |
| audit_log_untrustedstring(ab, name); |
| audit_log_format(ab, " data="); |
| audit_log_n_hex(ab, data, size); |
| audit_log_end(ab); |
| } |
| } |
| |
| /** |
| * tty_audit_buf_push - Push buffered data out |
| * |
| * Generate an audit message from the contents of @buf, which is owned by |
| * the current task. @buf->mutex must be locked. |
| */ |
| static void tty_audit_buf_push(struct tty_audit_buf *buf) |
| { |
| if (buf->valid == 0) |
| return; |
| if (audit_enabled == 0) { |
| buf->valid = 0; |
| return; |
| } |
| tty_audit_log("tty", buf->dev, buf->data, buf->valid); |
| buf->valid = 0; |
| } |
| |
| /** |
| * tty_audit_exit - Handle a task exit |
| * |
| * Make sure all buffered data is written out and deallocate the buffer. |
| * Only needs to be called if current->signal->tty_audit_buf != %NULL. |
| * |
| * The process is single-threaded at this point; no other threads share |
| * current->signal. |
| */ |
| void tty_audit_exit(void) |
| { |
| struct tty_audit_buf *buf; |
| |
| buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH)); |
| if (!buf) |
| return; |
| |
| tty_audit_buf_push(buf); |
| tty_audit_buf_free(buf); |
| } |
| |
| /** |
| * tty_audit_fork - Copy TTY audit state for a new task |
| * |
| * Set up TTY audit state in @sig from current. @sig needs no locking. |
| */ |
| void tty_audit_fork(struct signal_struct *sig) |
| { |
| sig->audit_tty = current->signal->audit_tty; |
| } |
| |
| /** |
| * tty_audit_tiocsti - Log TIOCSTI |
| */ |
| void tty_audit_tiocsti(struct tty_struct *tty, char ch) |
| { |
| dev_t dev; |
| |
| dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; |
| if (tty_audit_push()) |
| return; |
| |
| if (audit_enabled) { |
| kuid_t auid; |
| unsigned int sessionid; |
| |
| auid = audit_get_loginuid(current); |
| sessionid = audit_get_sessionid(current); |
| tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1); |
| } |
| } |
| |
| /** |
| * tty_audit_push - Flush current's pending audit data |
| * |
| * Returns 0 if success, -EPERM if tty audit is disabled |
| */ |
| int tty_audit_push(void) |
| { |
| struct tty_audit_buf *buf; |
| |
| if (~current->signal->audit_tty & AUDIT_TTY_ENABLE) |
| return -EPERM; |
| |
| buf = tty_audit_buf_ref(); |
| if (!IS_ERR_OR_NULL(buf)) { |
| mutex_lock(&buf->mutex); |
| tty_audit_buf_push(buf); |
| mutex_unlock(&buf->mutex); |
| } |
| return 0; |
| } |
| |
| /** |
| * tty_audit_buf_get - Get an audit buffer. |
| * |
| * Get an audit buffer, allocate it if necessary. Return %NULL |
| * if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already |
| * occurred. Otherwise, return a new reference to the buffer. |
| */ |
| static struct tty_audit_buf *tty_audit_buf_get(void) |
| { |
| struct tty_audit_buf *buf; |
| |
| buf = tty_audit_buf_ref(); |
| if (buf) |
| return buf; |
| |
| buf = tty_audit_buf_alloc(); |
| if (buf == NULL) { |
| audit_log_lost("out of memory in TTY auditing"); |
| return NULL; |
| } |
| |
| /* Race to use this buffer, free it if another wins */ |
| if (cmpxchg(¤t->signal->tty_audit_buf, NULL, buf) != NULL) |
| tty_audit_buf_free(buf); |
| return tty_audit_buf_ref(); |
| } |
| |
| /** |
| * tty_audit_add_data - Add data for TTY auditing. |
| * |
| * Audit @data of @size from @tty, if necessary. |
| */ |
| void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size) |
| { |
| struct tty_audit_buf *buf; |
| unsigned int icanon = !!L_ICANON(tty); |
| unsigned int audit_tty; |
| dev_t dev; |
| |
| audit_tty = READ_ONCE(current->signal->audit_tty); |
| if (~audit_tty & AUDIT_TTY_ENABLE) |
| return; |
| |
| if (unlikely(size == 0)) |
| return; |
| |
| if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
| && tty->driver->subtype == PTY_TYPE_MASTER) |
| return; |
| |
| if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty)) |
| return; |
| |
| buf = tty_audit_buf_get(); |
| if (IS_ERR_OR_NULL(buf)) |
| return; |
| |
| mutex_lock(&buf->mutex); |
| dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; |
| if (buf->dev != dev || buf->icanon != icanon) { |
| tty_audit_buf_push(buf); |
| buf->dev = dev; |
| buf->icanon = icanon; |
| } |
| do { |
| size_t run; |
| |
| run = N_TTY_BUF_SIZE - buf->valid; |
| if (run > size) |
| run = size; |
| memcpy(buf->data + buf->valid, data, run); |
| buf->valid += run; |
| data += run; |
| size -= run; |
| if (buf->valid == N_TTY_BUF_SIZE) |
| tty_audit_buf_push(buf); |
| } while (size != 0); |
| mutex_unlock(&buf->mutex); |
| } |