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522ed776 MT |
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> | |
5a0e3ad6 | 13 | #include <linux/slab.h> |
522ed776 MT |
14 | #include <linux/tty.h> |
15 | ||
16 | struct 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 | ||
25 | static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor, | |
6c633f27 | 26 | unsigned icanon) |
522ed776 MT |
27 | { |
28 | struct tty_audit_buf *buf; | |
29 | ||
66c6ceae | 30 | buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
522ed776 MT |
31 | if (!buf) |
32 | goto err; | |
c481c707 | 33 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
522ed776 MT |
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 | ||
44 | err_buf: | |
45 | kfree(buf); | |
46 | err: | |
47 | return NULL; | |
48 | } | |
49 | ||
50 | static void tty_audit_buf_free(struct tty_audit_buf *buf) | |
51 | { | |
52 | WARN_ON(buf->valid != 0); | |
c481c707 | 53 | kfree(buf->data); |
522ed776 MT |
54 | kfree(buf); |
55 | } | |
56 | ||
57 | static 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 | ||
1e641743 | 63 | static void tty_audit_log(const char *description, struct task_struct *tsk, |
e1760bd5 | 64 | kuid_t loginuid, unsigned sessionid, int major, |
1e641743 | 65 | int minor, unsigned char *data, size_t size) |
522ed776 MT |
66 | { |
67 | struct audit_buffer *ab; | |
68 | ||
522ed776 MT |
69 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
70 | if (ab) { | |
71 | char name[sizeof(tsk->comm)]; | |
cca080d9 | 72 | kuid_t uid = task_uid(tsk); |
522ed776 | 73 | |
1e641743 AV |
74 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u " |
75 | "major=%d minor=%d comm=", description, | |
cca080d9 EB |
76 | tsk->pid, |
77 | from_kuid(&init_user_ns, uid), | |
e1760bd5 EB |
78 | from_kuid(&init_user_ns, loginuid), |
79 | sessionid, | |
1e641743 | 80 | major, minor); |
522ed776 MT |
81 | get_task_comm(name, tsk); |
82 | audit_log_untrustedstring(ab, name); | |
83 | audit_log_format(ab, " data="); | |
1e641743 | 84 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
85 | audit_log_end(ab); |
86 | } | |
1e641743 AV |
87 | } |
88 | ||
89 | /** | |
90 | * tty_audit_buf_push - Push buffered data out | |
91 | * | |
92 | * Generate an audit message from the contents of @buf, which is owned by | |
93 | * @tsk with @loginuid. @buf->mutex must be locked. | |
94 | */ | |
e1760bd5 | 95 | static void tty_audit_buf_push(struct task_struct *tsk, kuid_t loginuid, |
1e641743 AV |
96 | unsigned int sessionid, |
97 | struct tty_audit_buf *buf) | |
98 | { | |
99 | if (buf->valid == 0) | |
100 | return; | |
00bff392 XF |
101 | if (audit_enabled == 0) { |
102 | buf->valid = 0; | |
1e641743 | 103 | return; |
00bff392 | 104 | } |
1e641743 AV |
105 | tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor, |
106 | buf->data, buf->valid); | |
522ed776 MT |
107 | buf->valid = 0; |
108 | } | |
109 | ||
110 | /** | |
111 | * tty_audit_buf_push_current - Push buffered data out | |
112 | * | |
113 | * Generate an audit message from the contents of @buf, which is owned by | |
114 | * the current task. @buf->mutex must be locked. | |
115 | */ | |
116 | static void tty_audit_buf_push_current(struct tty_audit_buf *buf) | |
117 | { | |
e1760bd5 | 118 | kuid_t auid = audit_get_loginuid(current); |
4746ec5b EP |
119 | unsigned int sessionid = audit_get_sessionid(current); |
120 | tty_audit_buf_push(current, auid, sessionid, buf); | |
522ed776 MT |
121 | } |
122 | ||
123 | /** | |
124 | * tty_audit_exit - Handle a task exit | |
125 | * | |
126 | * Make sure all buffered data is written out and deallocate the buffer. | |
127 | * Only needs to be called if current->signal->tty_audit_buf != %NULL. | |
128 | */ | |
129 | void tty_audit_exit(void) | |
130 | { | |
131 | struct tty_audit_buf *buf; | |
132 | ||
133 | spin_lock_irq(¤t->sighand->siglock); | |
134 | buf = current->signal->tty_audit_buf; | |
135 | current->signal->tty_audit_buf = NULL; | |
136 | spin_unlock_irq(¤t->sighand->siglock); | |
137 | if (!buf) | |
138 | return; | |
139 | ||
140 | mutex_lock(&buf->mutex); | |
141 | tty_audit_buf_push_current(buf); | |
142 | mutex_unlock(&buf->mutex); | |
143 | ||
144 | tty_audit_buf_put(buf); | |
145 | } | |
146 | ||
147 | /** | |
148 | * tty_audit_fork - Copy TTY audit state for a new task | |
149 | * | |
150 | * Set up TTY audit state in @sig from current. @sig needs no locking. | |
151 | */ | |
152 | void tty_audit_fork(struct signal_struct *sig) | |
153 | { | |
154 | spin_lock_irq(¤t->sighand->siglock); | |
155 | sig->audit_tty = current->signal->audit_tty; | |
156 | spin_unlock_irq(¤t->sighand->siglock); | |
522ed776 MT |
157 | } |
158 | ||
1e641743 AV |
159 | /** |
160 | * tty_audit_tiocsti - Log TIOCSTI | |
161 | */ | |
162 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
163 | { | |
164 | struct tty_audit_buf *buf; | |
165 | int major, minor, should_audit; | |
166 | ||
167 | spin_lock_irq(¤t->sighand->siglock); | |
168 | should_audit = current->signal->audit_tty; | |
169 | buf = current->signal->tty_audit_buf; | |
170 | if (buf) | |
171 | atomic_inc(&buf->count); | |
172 | spin_unlock_irq(¤t->sighand->siglock); | |
173 | ||
174 | major = tty->driver->major; | |
175 | minor = tty->driver->minor_start + tty->index; | |
176 | if (buf) { | |
177 | mutex_lock(&buf->mutex); | |
178 | if (buf->major == major && buf->minor == minor) | |
179 | tty_audit_buf_push_current(buf); | |
180 | mutex_unlock(&buf->mutex); | |
181 | tty_audit_buf_put(buf); | |
182 | } | |
183 | ||
184 | if (should_audit && audit_enabled) { | |
e1760bd5 | 185 | kuid_t auid; |
1e641743 AV |
186 | unsigned int sessionid; |
187 | ||
188 | auid = audit_get_loginuid(current); | |
189 | sessionid = audit_get_sessionid(current); | |
190 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, | |
191 | minor, &ch, 1); | |
192 | } | |
193 | } | |
194 | ||
522ed776 | 195 | /** |
3c80fe4a TG |
196 | * tty_audit_push_task - Flush task's pending audit data |
197 | * @tsk: task pointer | |
198 | * @loginuid: sender login uid | |
199 | * @sessionid: sender session id | |
200 | * | |
201 | * Called with a ref on @tsk held. Try to lock sighand and get a | |
202 | * reference to the tty audit buffer if available. | |
203 | * Flush the buffer or return an appropriate error code. | |
522ed776 | 204 | */ |
dc9eb698 | 205 | int tty_audit_push_task(struct task_struct *tsk) |
522ed776 | 206 | { |
3c80fe4a TG |
207 | struct tty_audit_buf *buf = ERR_PTR(-EPERM); |
208 | unsigned long flags; | |
dc9eb698 EP |
209 | kuid_t loginuid = audit_get_loginuid(tsk); |
210 | u32 sessionid = audit_get_sessionid(tsk); | |
522ed776 | 211 | |
3c80fe4a TG |
212 | if (!lock_task_sighand(tsk, &flags)) |
213 | return -ESRCH; | |
214 | ||
215 | if (tsk->signal->audit_tty) { | |
216 | buf = tsk->signal->tty_audit_buf; | |
217 | if (buf) | |
218 | atomic_inc(&buf->count); | |
219 | } | |
220 | unlock_task_sighand(tsk, &flags); | |
221 | ||
222 | /* | |
223 | * Return 0 when signal->audit_tty set | |
224 | * but tsk->signal->tty_audit_buf == NULL. | |
225 | */ | |
226 | if (!buf || IS_ERR(buf)) | |
227 | return PTR_ERR(buf); | |
522ed776 MT |
228 | |
229 | mutex_lock(&buf->mutex); | |
4746ec5b | 230 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
231 | mutex_unlock(&buf->mutex); |
232 | ||
233 | tty_audit_buf_put(buf); | |
3c80fe4a | 234 | return 0; |
522ed776 MT |
235 | } |
236 | ||
237 | /** | |
238 | * tty_audit_buf_get - Get an audit buffer. | |
239 | * | |
240 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL | |
241 | * if TTY auditing is disabled or out of memory. Otherwise, return a new | |
242 | * reference to the buffer. | |
243 | */ | |
6c633f27 JS |
244 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, |
245 | unsigned icanon) | |
522ed776 MT |
246 | { |
247 | struct tty_audit_buf *buf, *buf2; | |
248 | ||
249 | buf = NULL; | |
250 | buf2 = NULL; | |
251 | spin_lock_irq(¤t->sighand->siglock); | |
252 | if (likely(!current->signal->audit_tty)) | |
253 | goto out; | |
254 | buf = current->signal->tty_audit_buf; | |
255 | if (buf) { | |
256 | atomic_inc(&buf->count); | |
257 | goto out; | |
258 | } | |
259 | spin_unlock_irq(¤t->sighand->siglock); | |
260 | ||
261 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
262 | tty->driver->minor_start + tty->index, | |
6c633f27 | 263 | icanon); |
522ed776 MT |
264 | if (buf2 == NULL) { |
265 | audit_log_lost("out of memory in TTY auditing"); | |
266 | return NULL; | |
267 | } | |
268 | ||
269 | spin_lock_irq(¤t->sighand->siglock); | |
270 | if (!current->signal->audit_tty) | |
271 | goto out; | |
272 | buf = current->signal->tty_audit_buf; | |
273 | if (!buf) { | |
274 | current->signal->tty_audit_buf = buf2; | |
275 | buf = buf2; | |
276 | buf2 = NULL; | |
277 | } | |
278 | atomic_inc(&buf->count); | |
279 | /* Fall through */ | |
280 | out: | |
281 | spin_unlock_irq(¤t->sighand->siglock); | |
282 | if (buf2) | |
283 | tty_audit_buf_free(buf2); | |
284 | return buf; | |
285 | } | |
286 | ||
287 | /** | |
288 | * tty_audit_add_data - Add data for TTY auditing. | |
289 | * | |
290 | * Audit @data of @size from @tty, if necessary. | |
291 | */ | |
292 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
6c633f27 | 293 | size_t size, unsigned icanon) |
522ed776 MT |
294 | { |
295 | struct tty_audit_buf *buf; | |
296 | int major, minor; | |
297 | ||
298 | if (unlikely(size == 0)) | |
299 | return; | |
300 | ||
41126226 MT |
301 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
302 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
303 | return; | |
304 | ||
6c633f27 | 305 | buf = tty_audit_buf_get(tty, icanon); |
522ed776 MT |
306 | if (!buf) |
307 | return; | |
308 | ||
309 | mutex_lock(&buf->mutex); | |
310 | major = tty->driver->major; | |
311 | minor = tty->driver->minor_start + tty->index; | |
312 | if (buf->major != major || buf->minor != minor | |
6c633f27 | 313 | || buf->icanon != icanon) { |
522ed776 MT |
314 | tty_audit_buf_push_current(buf); |
315 | buf->major = major; | |
316 | buf->minor = minor; | |
6c633f27 | 317 | buf->icanon = icanon; |
522ed776 MT |
318 | } |
319 | do { | |
320 | size_t run; | |
321 | ||
322 | run = N_TTY_BUF_SIZE - buf->valid; | |
323 | if (run > size) | |
324 | run = size; | |
325 | memcpy(buf->data + buf->valid, data, run); | |
326 | buf->valid += run; | |
327 | data += run; | |
328 | size -= run; | |
329 | if (buf->valid == N_TTY_BUF_SIZE) | |
330 | tty_audit_buf_push_current(buf); | |
331 | } while (size != 0); | |
332 | mutex_unlock(&buf->mutex); | |
333 | tty_audit_buf_put(buf); | |
334 | } | |
335 | ||
336 | /** | |
337 | * tty_audit_push - Push buffered data out | |
338 | * | |
339 | * Make sure no audit data is pending for @tty on the current process. | |
340 | */ | |
341 | void tty_audit_push(struct tty_struct *tty) | |
342 | { | |
343 | struct tty_audit_buf *buf; | |
344 | ||
345 | spin_lock_irq(¤t->sighand->siglock); | |
346 | if (likely(!current->signal->audit_tty)) { | |
347 | spin_unlock_irq(¤t->sighand->siglock); | |
348 | return; | |
349 | } | |
350 | buf = current->signal->tty_audit_buf; | |
351 | if (buf) | |
352 | atomic_inc(&buf->count); | |
353 | spin_unlock_irq(¤t->sighand->siglock); | |
354 | ||
355 | if (buf) { | |
356 | int major, minor; | |
357 | ||
358 | major = tty->driver->major; | |
359 | minor = tty->driver->minor_start + tty->index; | |
360 | mutex_lock(&buf->mutex); | |
361 | if (buf->major == major && buf->minor == minor) | |
362 | tty_audit_buf_push_current(buf); | |
363 | mutex_unlock(&buf->mutex); | |
364 | tty_audit_buf_put(buf); | |
365 | } | |
366 | } |