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Miloslav Trmac522ed772007-07-15 23:40:56 -07001/*
2 * Creating audit events from TTY input.
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All rights reserved. This copyrighted
5 * material is made available to anyone wishing to use, modify, copy, or
6 * redistribute it subject to the terms and conditions of the GNU General
7 * Public License v.2.
8 *
9 * Authors: Miloslav Trmac <mitr@redhat.com>
10 */
11
12#include <linux/audit.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090013#include <linux/slab.h>
Miloslav Trmac522ed772007-07-15 23:40:56 -070014#include <linux/tty.h>
15
16struct tty_audit_buf {
17 atomic_t count;
18 struct mutex mutex; /* Protects all data below */
19 int major, minor; /* The TTY which the data is from */
20 unsigned icanon:1;
21 size_t valid;
22 unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */
23};
24
25static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
Jiri Slaby6c633f22012-10-18 22:26:37 +020026 unsigned icanon)
Miloslav Trmac522ed772007-07-15 23:40:56 -070027{
28 struct tty_audit_buf *buf;
29
Alan Cox66c6cea2008-02-08 04:18:46 -080030 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
Miloslav Trmac522ed772007-07-15 23:40:56 -070031 if (!buf)
32 goto err;
Alan Coxc481c702009-06-11 13:04:27 +010033 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
Miloslav Trmac522ed772007-07-15 23:40:56 -070034 if (!buf->data)
35 goto err_buf;
36 atomic_set(&buf->count, 1);
37 mutex_init(&buf->mutex);
38 buf->major = major;
39 buf->minor = minor;
40 buf->icanon = icanon;
41 buf->valid = 0;
42 return buf;
43
44err_buf:
45 kfree(buf);
46err:
47 return NULL;
48}
49
50static void tty_audit_buf_free(struct tty_audit_buf *buf)
51{
52 WARN_ON(buf->valid != 0);
Alan Coxc481c702009-06-11 13:04:27 +010053 kfree(buf->data);
Miloslav Trmac522ed772007-07-15 23:40:56 -070054 kfree(buf);
55}
56
57static void tty_audit_buf_put(struct tty_audit_buf *buf)
58{
59 if (atomic_dec_and_test(&buf->count))
60 tty_audit_buf_free(buf);
61}
62
Eric Paris152f4972013-04-19 13:56:11 -040063static void tty_audit_log(const char *description, int major, int minor,
64 unsigned char *data, size_t size)
Al Viro1e641742008-12-09 09:23:33 +000065{
66 struct audit_buffer *ab;
Eric Paris152f4972013-04-19 13:56:11 -040067 struct task_struct *tsk = current;
Richard Guy Briggsf1dc4862013-12-11 13:52:26 -050068 pid_t pid = task_pid_nr(tsk);
Eric Paris152f4972013-04-19 13:56:11 -040069 uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
70 uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
Eric Paris4440e852013-11-27 17:35:17 -050071 unsigned int sessionid = audit_get_sessionid(tsk);
Al Viro1e641742008-12-09 09:23:33 +000072
73 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
74 if (ab) {
75 char name[sizeof(tsk->comm)];
Al Viro1e641742008-12-09 09:23:33 +000076
Eric Paris152f4972013-04-19 13:56:11 -040077 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
Richard Guy Briggsf1dc4862013-12-11 13:52:26 -050078 " minor=%d comm=", description, pid, uid,
Eric Paris152f4972013-04-19 13:56:11 -040079 loginuid, sessionid, major, minor);
Al Viro1e641742008-12-09 09:23:33 +000080 get_task_comm(name, tsk);
81 audit_log_untrustedstring(ab, name);
82 audit_log_format(ab, " data=");
83 audit_log_n_hex(ab, data, size);
84 audit_log_end(ab);
85 }
86}
87
Miloslav Trmac522ed772007-07-15 23:40:56 -070088/**
89 * tty_audit_buf_push - Push buffered data out
90 *
91 * Generate an audit message from the contents of @buf, which is owned by
Eric Paris152f4972013-04-19 13:56:11 -040092 * the current task. @buf->mutex must be locked.
Miloslav Trmac522ed772007-07-15 23:40:56 -070093 */
Eric Paris152f4972013-04-19 13:56:11 -040094static void tty_audit_buf_push(struct tty_audit_buf *buf)
Miloslav Trmac522ed772007-07-15 23:40:56 -070095{
Miloslav Trmac522ed772007-07-15 23:40:56 -070096 if (buf->valid == 0)
97 return;
Xiaotian Feng00bff392011-03-03 18:08:24 +080098 if (audit_enabled == 0) {
99 buf->valid = 0;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700100 return;
Xiaotian Feng00bff392011-03-03 18:08:24 +0800101 }
Eric Paris152f4972013-04-19 13:56:11 -0400102 tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700103 buf->valid = 0;
104}
105
106/**
Miloslav Trmac522ed772007-07-15 23:40:56 -0700107 * tty_audit_exit - Handle a task exit
108 *
109 * Make sure all buffered data is written out and deallocate the buffer.
110 * Only needs to be called if current->signal->tty_audit_buf != %NULL.
111 */
112void tty_audit_exit(void)
113{
114 struct tty_audit_buf *buf;
115
Miloslav Trmac522ed772007-07-15 23:40:56 -0700116 buf = current->signal->tty_audit_buf;
117 current->signal->tty_audit_buf = NULL;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700118 if (!buf)
119 return;
120
121 mutex_lock(&buf->mutex);
Eric Paris152f4972013-04-19 13:56:11 -0400122 tty_audit_buf_push(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700123 mutex_unlock(&buf->mutex);
124
125 tty_audit_buf_put(buf);
126}
127
128/**
129 * tty_audit_fork - Copy TTY audit state for a new task
130 *
131 * Set up TTY audit state in @sig from current. @sig needs no locking.
132 */
133void tty_audit_fork(struct signal_struct *sig)
134{
Miloslav Trmac522ed772007-07-15 23:40:56 -0700135 sig->audit_tty = current->signal->audit_tty;
Richard Guy Briggs46e959e2013-05-03 14:03:50 -0400136 sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700137}
138
139/**
Al Viro1e641742008-12-09 09:23:33 +0000140 * tty_audit_tiocsti - Log TIOCSTI
141 */
142void tty_audit_tiocsti(struct tty_struct *tty, char ch)
143{
144 struct tty_audit_buf *buf;
145 int major, minor, should_audit;
Eric Parisbde02ca2013-04-30 11:01:14 -0400146 unsigned long flags;
Al Viro1e641742008-12-09 09:23:33 +0000147
Eric Parisbde02ca2013-04-30 11:01:14 -0400148 spin_lock_irqsave(&current->sighand->siglock, flags);
Al Viro1e641742008-12-09 09:23:33 +0000149 should_audit = current->signal->audit_tty;
150 buf = current->signal->tty_audit_buf;
151 if (buf)
152 atomic_inc(&buf->count);
Eric Parisbde02ca2013-04-30 11:01:14 -0400153 spin_unlock_irqrestore(&current->sighand->siglock, flags);
Al Viro1e641742008-12-09 09:23:33 +0000154
155 major = tty->driver->major;
156 minor = tty->driver->minor_start + tty->index;
157 if (buf) {
158 mutex_lock(&buf->mutex);
159 if (buf->major == major && buf->minor == minor)
Eric Paris152f4972013-04-19 13:56:11 -0400160 tty_audit_buf_push(buf);
Al Viro1e641742008-12-09 09:23:33 +0000161 mutex_unlock(&buf->mutex);
162 tty_audit_buf_put(buf);
163 }
164
165 if (should_audit && audit_enabled) {
Eric W. Biedermane1760bd2012-09-10 22:39:43 -0700166 kuid_t auid;
Al Viro1e641742008-12-09 09:23:33 +0000167 unsigned int sessionid;
168
169 auid = audit_get_loginuid(current);
170 sessionid = audit_get_sessionid(current);
Eric Paris152f4972013-04-19 13:56:11 -0400171 tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1);
Al Viro1e641742008-12-09 09:23:33 +0000172 }
173}
174
175/**
Eric Paris152f4972013-04-19 13:56:11 -0400176 * tty_audit_push_current - Flush current's pending audit data
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000177 *
Eric Paris152f4972013-04-19 13:56:11 -0400178 * Try to lock sighand and get a reference to the tty audit buffer if available.
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000179 * Flush the buffer or return an appropriate error code.
Miloslav Trmac522ed772007-07-15 23:40:56 -0700180 */
Eric Paris152f4972013-04-19 13:56:11 -0400181int tty_audit_push_current(void)
Miloslav Trmac522ed772007-07-15 23:40:56 -0700182{
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000183 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
Eric Paris152f4972013-04-19 13:56:11 -0400184 struct task_struct *tsk = current;
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000185 unsigned long flags;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700186
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000187 if (!lock_task_sighand(tsk, &flags))
188 return -ESRCH;
189
190 if (tsk->signal->audit_tty) {
191 buf = tsk->signal->tty_audit_buf;
192 if (buf)
193 atomic_inc(&buf->count);
194 }
195 unlock_task_sighand(tsk, &flags);
196
197 /*
198 * Return 0 when signal->audit_tty set
199 * but tsk->signal->tty_audit_buf == NULL.
200 */
201 if (!buf || IS_ERR(buf))
202 return PTR_ERR(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700203
204 mutex_lock(&buf->mutex);
Eric Paris152f4972013-04-19 13:56:11 -0400205 tty_audit_buf_push(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700206 mutex_unlock(&buf->mutex);
207
208 tty_audit_buf_put(buf);
Thomas Gleixner3c80fe42009-12-09 14:19:31 +0000209 return 0;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700210}
211
212/**
213 * tty_audit_buf_get - Get an audit buffer.
214 *
215 * Get an audit buffer for @tty, allocate it if necessary. Return %NULL
216 * if TTY auditing is disabled or out of memory. Otherwise, return a new
217 * reference to the buffer.
218 */
Jiri Slaby6c633f22012-10-18 22:26:37 +0200219static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
220 unsigned icanon)
Miloslav Trmac522ed772007-07-15 23:40:56 -0700221{
222 struct tty_audit_buf *buf, *buf2;
Eric Parisbde02ca2013-04-30 11:01:14 -0400223 unsigned long flags;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700224
225 buf = NULL;
226 buf2 = NULL;
Eric Parisbde02ca2013-04-30 11:01:14 -0400227 spin_lock_irqsave(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700228 if (likely(!current->signal->audit_tty))
229 goto out;
230 buf = current->signal->tty_audit_buf;
231 if (buf) {
232 atomic_inc(&buf->count);
233 goto out;
234 }
Eric Parisbde02ca2013-04-30 11:01:14 -0400235 spin_unlock_irqrestore(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700236
237 buf2 = tty_audit_buf_alloc(tty->driver->major,
238 tty->driver->minor_start + tty->index,
Jiri Slaby6c633f22012-10-18 22:26:37 +0200239 icanon);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700240 if (buf2 == NULL) {
241 audit_log_lost("out of memory in TTY auditing");
242 return NULL;
243 }
244
Eric Parisbde02ca2013-04-30 11:01:14 -0400245 spin_lock_irqsave(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700246 if (!current->signal->audit_tty)
247 goto out;
248 buf = current->signal->tty_audit_buf;
249 if (!buf) {
250 current->signal->tty_audit_buf = buf2;
251 buf = buf2;
252 buf2 = NULL;
253 }
254 atomic_inc(&buf->count);
255 /* Fall through */
256 out:
Eric Parisbde02ca2013-04-30 11:01:14 -0400257 spin_unlock_irqrestore(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700258 if (buf2)
259 tty_audit_buf_free(buf2);
260 return buf;
261}
262
263/**
264 * tty_audit_add_data - Add data for TTY auditing.
265 *
266 * Audit @data of @size from @tty, if necessary.
267 */
268void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
Jiri Slaby6c633f22012-10-18 22:26:37 +0200269 size_t size, unsigned icanon)
Miloslav Trmac522ed772007-07-15 23:40:56 -0700270{
271 struct tty_audit_buf *buf;
272 int major, minor;
Richard Guy Briggs46e959e2013-05-03 14:03:50 -0400273 int audit_log_tty_passwd;
274 unsigned long flags;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700275
276 if (unlikely(size == 0))
277 return;
278
Richard Guy Briggs46e959e2013-05-03 14:03:50 -0400279 spin_lock_irqsave(&current->sighand->siglock, flags);
280 audit_log_tty_passwd = current->signal->audit_tty_log_passwd;
281 spin_unlock_irqrestore(&current->sighand->siglock, flags);
282 if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))
283 return;
284
Miloslav Trmac41126222008-04-18 13:30:14 -0700285 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
286 && tty->driver->subtype == PTY_TYPE_MASTER)
287 return;
288
Jiri Slaby6c633f22012-10-18 22:26:37 +0200289 buf = tty_audit_buf_get(tty, icanon);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700290 if (!buf)
291 return;
292
293 mutex_lock(&buf->mutex);
294 major = tty->driver->major;
295 minor = tty->driver->minor_start + tty->index;
296 if (buf->major != major || buf->minor != minor
Jiri Slaby6c633f22012-10-18 22:26:37 +0200297 || buf->icanon != icanon) {
Eric Paris152f4972013-04-19 13:56:11 -0400298 tty_audit_buf_push(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700299 buf->major = major;
300 buf->minor = minor;
Jiri Slaby6c633f22012-10-18 22:26:37 +0200301 buf->icanon = icanon;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700302 }
303 do {
304 size_t run;
305
306 run = N_TTY_BUF_SIZE - buf->valid;
307 if (run > size)
308 run = size;
309 memcpy(buf->data + buf->valid, data, run);
310 buf->valid += run;
311 data += run;
312 size -= run;
313 if (buf->valid == N_TTY_BUF_SIZE)
Eric Paris152f4972013-04-19 13:56:11 -0400314 tty_audit_buf_push(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700315 } while (size != 0);
316 mutex_unlock(&buf->mutex);
317 tty_audit_buf_put(buf);
318}
319
320/**
321 * tty_audit_push - Push buffered data out
322 *
323 * Make sure no audit data is pending for @tty on the current process.
324 */
325void tty_audit_push(struct tty_struct *tty)
326{
327 struct tty_audit_buf *buf;
Eric Parisbde02ca2013-04-30 11:01:14 -0400328 unsigned long flags;
Miloslav Trmac522ed772007-07-15 23:40:56 -0700329
Eric Parisbde02ca2013-04-30 11:01:14 -0400330 spin_lock_irqsave(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700331 if (likely(!current->signal->audit_tty)) {
Eric Parisbde02ca2013-04-30 11:01:14 -0400332 spin_unlock_irqrestore(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700333 return;
334 }
335 buf = current->signal->tty_audit_buf;
336 if (buf)
337 atomic_inc(&buf->count);
Eric Parisbde02ca2013-04-30 11:01:14 -0400338 spin_unlock_irqrestore(&current->sighand->siglock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700339
340 if (buf) {
341 int major, minor;
342
343 major = tty->driver->major;
344 minor = tty->driver->minor_start + tty->index;
345 mutex_lock(&buf->mutex);
346 if (buf->major == major && buf->minor == minor)
Eric Paris152f4972013-04-19 13:56:11 -0400347 tty_audit_buf_push(buf);
Miloslav Trmac522ed772007-07-15 23:40:56 -0700348 mutex_unlock(&buf->mutex);
349 tty_audit_buf_put(buf);
350 }
351}