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1/*
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>
13#include <linux/slab.h>
14#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,
26 int icanon)
27{
28 struct tty_audit_buf *buf;
29
30 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
31 if (!buf)
32 goto err;
33 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
34 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);
53 kfree(buf->data);
54 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
63static void tty_audit_log(const char *description, struct task_struct *tsk,
64 uid_t loginuid, unsigned sessionid, int major,
65 int minor, unsigned char *data, size_t size)
66{
67 struct audit_buffer *ab;
68
69 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
70 if (ab) {
71 char name[sizeof(tsk->comm)];
72 uid_t uid = task_uid(tsk);
73
74 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
75 "major=%d minor=%d comm=", description,
76 tsk->pid, uid, loginuid, sessionid,
77 major, minor);
78 get_task_comm(name, tsk);
79 audit_log_untrustedstring(ab, name);
80 audit_log_format(ab, " data=");
81 audit_log_n_hex(ab, data, size);
82 audit_log_end(ab);
83 }
84}
85
86/**
87 * tty_audit_buf_push - Push buffered data out
88 *
89 * Generate an audit message from the contents of @buf, which is owned by
90 * @tsk with @loginuid. @buf->mutex must be locked.
91 */
92static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
93 unsigned int sessionid,
94 struct tty_audit_buf *buf)
95{
96 if (buf->valid == 0)
97 return;
98 if (audit_enabled == 0) {
99 buf->valid = 0;
100 return;
101 }
102 tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
103 buf->data, buf->valid);
104 buf->valid = 0;
105}
106
107/**
108 * tty_audit_buf_push_current - Push buffered data out
109 *
110 * Generate an audit message from the contents of @buf, which is owned by
111 * the current task. @buf->mutex must be locked.
112 */
113static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
114{
115 uid_t auid = audit_get_loginuid(current);
116 unsigned int sessionid = audit_get_sessionid(current);
117 tty_audit_buf_push(current, auid, sessionid, buf);
118}
119
120/**
121 * tty_audit_exit - Handle a task exit
122 *
123 * Make sure all buffered data is written out and deallocate the buffer.
124 * Only needs to be called if current->signal->tty_audit_buf != %NULL.
125 */
126void tty_audit_exit(void)
127{
128 struct tty_audit_buf *buf;
129
130 spin_lock_irq(¤t->sighand->siglock);
131 buf = current->signal->tty_audit_buf;
132 current->signal->tty_audit_buf = NULL;
133 spin_unlock_irq(¤t->sighand->siglock);
134 if (!buf)
135 return;
136
137 mutex_lock(&buf->mutex);
138 tty_audit_buf_push_current(buf);
139 mutex_unlock(&buf->mutex);
140
141 tty_audit_buf_put(buf);
142}
143
144/**
145 * tty_audit_fork - Copy TTY audit state for a new task
146 *
147 * Set up TTY audit state in @sig from current. @sig needs no locking.
148 */
149void tty_audit_fork(struct signal_struct *sig)
150{
151 spin_lock_irq(¤t->sighand->siglock);
152 sig->audit_tty = current->signal->audit_tty;
153 spin_unlock_irq(¤t->sighand->siglock);
154}
155
156/**
157 * tty_audit_tiocsti - Log TIOCSTI
158 */
159void tty_audit_tiocsti(struct tty_struct *tty, char ch)
160{
161 struct tty_audit_buf *buf;
162 int major, minor, should_audit;
163
164 spin_lock_irq(¤t->sighand->siglock);
165 should_audit = current->signal->audit_tty;
166 buf = current->signal->tty_audit_buf;
167 if (buf)
168 atomic_inc(&buf->count);
169 spin_unlock_irq(¤t->sighand->siglock);
170
171 major = tty->driver->major;
172 minor = tty->driver->minor_start + tty->index;
173 if (buf) {
174 mutex_lock(&buf->mutex);
175 if (buf->major == major && buf->minor == minor)
176 tty_audit_buf_push_current(buf);
177 mutex_unlock(&buf->mutex);
178 tty_audit_buf_put(buf);
179 }
180
181 if (should_audit && audit_enabled) {
182 uid_t auid;
183 unsigned int sessionid;
184
185 auid = audit_get_loginuid(current);
186 sessionid = audit_get_sessionid(current);
187 tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
188 minor, &ch, 1);
189 }
190}
191
192/**
193 * tty_audit_push_task - Flush task's pending audit data
194 * @tsk: task pointer
195 * @loginuid: sender login uid
196 * @sessionid: sender session id
197 *
198 * Called with a ref on @tsk held. Try to lock sighand and get a
199 * reference to the tty audit buffer if available.
200 * Flush the buffer or return an appropriate error code.
201 */
202int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
203{
204 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
205 unsigned long flags;
206
207 if (!lock_task_sighand(tsk, &flags))
208 return -ESRCH;
209
210 if (tsk->signal->audit_tty) {
211 buf = tsk->signal->tty_audit_buf;
212 if (buf)
213 atomic_inc(&buf->count);
214 }
215 unlock_task_sighand(tsk, &flags);
216
217 /*
218 * Return 0 when signal->audit_tty set
219 * but tsk->signal->tty_audit_buf == NULL.
220 */
221 if (!buf || IS_ERR(buf))
222 return PTR_ERR(buf);
223
224 mutex_lock(&buf->mutex);
225 tty_audit_buf_push(tsk, loginuid, sessionid, buf);
226 mutex_unlock(&buf->mutex);
227
228 tty_audit_buf_put(buf);
229 return 0;
230}
231
232/**
233 * tty_audit_buf_get - Get an audit buffer.
234 *
235 * Get an audit buffer for @tty, allocate it if necessary. Return %NULL
236 * if TTY auditing is disabled or out of memory. Otherwise, return a new
237 * reference to the buffer.
238 */
239static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
240{
241 struct tty_audit_buf *buf, *buf2;
242
243 buf = NULL;
244 buf2 = NULL;
245 spin_lock_irq(¤t->sighand->siglock);
246 if (likely(!current->signal->audit_tty))
247 goto out;
248 buf = current->signal->tty_audit_buf;
249 if (buf) {
250 atomic_inc(&buf->count);
251 goto out;
252 }
253 spin_unlock_irq(¤t->sighand->siglock);
254
255 buf2 = tty_audit_buf_alloc(tty->driver->major,
256 tty->driver->minor_start + tty->index,
257 tty->icanon);
258 if (buf2 == NULL) {
259 audit_log_lost("out of memory in TTY auditing");
260 return NULL;
261 }
262
263 spin_lock_irq(¤t->sighand->siglock);
264 if (!current->signal->audit_tty)
265 goto out;
266 buf = current->signal->tty_audit_buf;
267 if (!buf) {
268 current->signal->tty_audit_buf = buf2;
269 buf = buf2;
270 buf2 = NULL;
271 }
272 atomic_inc(&buf->count);
273 /* Fall through */
274 out:
275 spin_unlock_irq(¤t->sighand->siglock);
276 if (buf2)
277 tty_audit_buf_free(buf2);
278 return buf;
279}
280
281/**
282 * tty_audit_add_data - Add data for TTY auditing.
283 *
284 * Audit @data of @size from @tty, if necessary.
285 */
286void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
287 size_t size)
288{
289 struct tty_audit_buf *buf;
290 int major, minor;
291
292 if (unlikely(size == 0))
293 return;
294
295 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
296 && tty->driver->subtype == PTY_TYPE_MASTER)
297 return;
298
299 buf = tty_audit_buf_get(tty);
300 if (!buf)
301 return;
302
303 mutex_lock(&buf->mutex);
304 major = tty->driver->major;
305 minor = tty->driver->minor_start + tty->index;
306 if (buf->major != major || buf->minor != minor
307 || buf->icanon != tty->icanon) {
308 tty_audit_buf_push_current(buf);
309 buf->major = major;
310 buf->minor = minor;
311 buf->icanon = tty->icanon;
312 }
313 do {
314 size_t run;
315
316 run = N_TTY_BUF_SIZE - buf->valid;
317 if (run > size)
318 run = size;
319 memcpy(buf->data + buf->valid, data, run);
320 buf->valid += run;
321 data += run;
322 size -= run;
323 if (buf->valid == N_TTY_BUF_SIZE)
324 tty_audit_buf_push_current(buf);
325 } while (size != 0);
326 mutex_unlock(&buf->mutex);
327 tty_audit_buf_put(buf);
328}
329
330/**
331 * tty_audit_push - Push buffered data out
332 *
333 * Make sure no audit data is pending for @tty on the current process.
334 */
335void tty_audit_push(struct tty_struct *tty)
336{
337 struct tty_audit_buf *buf;
338
339 spin_lock_irq(¤t->sighand->siglock);
340 if (likely(!current->signal->audit_tty)) {
341 spin_unlock_irq(¤t->sighand->siglock);
342 return;
343 }
344 buf = current->signal->tty_audit_buf;
345 if (buf)
346 atomic_inc(&buf->count);
347 spin_unlock_irq(¤t->sighand->siglock);
348
349 if (buf) {
350 int major, minor;
351
352 major = tty->driver->major;
353 minor = tty->driver->minor_start + tty->index;
354 mutex_lock(&buf->mutex);
355 if (buf->major == major && buf->minor == minor)
356 tty_audit_buf_push_current(buf);
357 mutex_unlock(&buf->mutex);
358 tty_audit_buf_put(buf);
359 }
360}
1/*
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>
13#include <linux/slab.h>
14#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,
26 unsigned icanon)
27{
28 struct tty_audit_buf *buf;
29
30 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
31 if (!buf)
32 goto err;
33 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
34 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);
53 kfree(buf->data);
54 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
63static void tty_audit_log(const char *description, int major, int minor,
64 unsigned char *data, size_t size)
65{
66 struct audit_buffer *ab;
67 struct task_struct *tsk = current;
68 pid_t pid = task_pid_nr(tsk);
69 uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
70 uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
71 unsigned int sessionid = audit_get_sessionid(tsk);
72
73 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
74 if (ab) {
75 char name[sizeof(tsk->comm)];
76
77 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
78 " minor=%d comm=", description, pid, uid,
79 loginuid, sessionid, major, minor);
80 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
88/**
89 * tty_audit_buf_push - Push buffered data out
90 *
91 * Generate an audit message from the contents of @buf, which is owned by
92 * the current task. @buf->mutex must be locked.
93 */
94static void tty_audit_buf_push(struct tty_audit_buf *buf)
95{
96 if (buf->valid == 0)
97 return;
98 if (audit_enabled == 0) {
99 buf->valid = 0;
100 return;
101 }
102 tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
103 buf->valid = 0;
104}
105
106/**
107 * 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
116 buf = current->signal->tty_audit_buf;
117 current->signal->tty_audit_buf = NULL;
118 if (!buf)
119 return;
120
121 mutex_lock(&buf->mutex);
122 tty_audit_buf_push(buf);
123 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{
135 sig->audit_tty = current->signal->audit_tty;
136 sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd;
137}
138
139/**
140 * 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;
146 unsigned long flags;
147
148 spin_lock_irqsave(¤t->sighand->siglock, flags);
149 should_audit = current->signal->audit_tty;
150 buf = current->signal->tty_audit_buf;
151 if (buf)
152 atomic_inc(&buf->count);
153 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
154
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)
160 tty_audit_buf_push(buf);
161 mutex_unlock(&buf->mutex);
162 tty_audit_buf_put(buf);
163 }
164
165 if (should_audit && audit_enabled) {
166 kuid_t auid;
167 unsigned int sessionid;
168
169 auid = audit_get_loginuid(current);
170 sessionid = audit_get_sessionid(current);
171 tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1);
172 }
173}
174
175/**
176 * tty_audit_push_current - Flush current's pending audit data
177 *
178 * Try to lock sighand and get a reference to the tty audit buffer if available.
179 * Flush the buffer or return an appropriate error code.
180 */
181int tty_audit_push_current(void)
182{
183 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
184 struct task_struct *tsk = current;
185 unsigned long flags;
186
187 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);
203
204 mutex_lock(&buf->mutex);
205 tty_audit_buf_push(buf);
206 mutex_unlock(&buf->mutex);
207
208 tty_audit_buf_put(buf);
209 return 0;
210}
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 */
219static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
220 unsigned icanon)
221{
222 struct tty_audit_buf *buf, *buf2;
223 unsigned long flags;
224
225 buf = NULL;
226 buf2 = NULL;
227 spin_lock_irqsave(¤t->sighand->siglock, flags);
228 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 }
235 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
236
237 buf2 = tty_audit_buf_alloc(tty->driver->major,
238 tty->driver->minor_start + tty->index,
239 icanon);
240 if (buf2 == NULL) {
241 audit_log_lost("out of memory in TTY auditing");
242 return NULL;
243 }
244
245 spin_lock_irqsave(¤t->sighand->siglock, flags);
246 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:
257 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
258 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,
269 size_t size, unsigned icanon)
270{
271 struct tty_audit_buf *buf;
272 int major, minor;
273 int audit_log_tty_passwd;
274 unsigned long flags;
275
276 if (unlikely(size == 0))
277 return;
278
279 spin_lock_irqsave(¤t->sighand->siglock, flags);
280 audit_log_tty_passwd = current->signal->audit_tty_log_passwd;
281 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
282 if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))
283 return;
284
285 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
286 && tty->driver->subtype == PTY_TYPE_MASTER)
287 return;
288
289 buf = tty_audit_buf_get(tty, icanon);
290 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
297 || buf->icanon != icanon) {
298 tty_audit_buf_push(buf);
299 buf->major = major;
300 buf->minor = minor;
301 buf->icanon = icanon;
302 }
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)
314 tty_audit_buf_push(buf);
315 } 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;
328 unsigned long flags;
329
330 spin_lock_irqsave(¤t->sighand->siglock, flags);
331 if (likely(!current->signal->audit_tty)) {
332 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
333 return;
334 }
335 buf = current->signal->tty_audit_buf;
336 if (buf)
337 atomic_inc(&buf->count);
338 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
339
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)
347 tty_audit_buf_push(buf);
348 mutex_unlock(&buf->mutex);
349 tty_audit_buf_put(buf);
350 }
351}