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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 | ||
152f497b EP |
63 | static void tty_audit_log(const char *description, int major, int minor, |
64 | unsigned char *data, size_t size) | |
522ed776 MT |
65 | { |
66 | struct audit_buffer *ab; | |
152f497b | 67 | struct task_struct *tsk = current; |
f1dc4867 | 68 | pid_t pid = task_pid_nr(tsk); |
152f497b EP |
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)); | |
4440e854 | 71 | unsigned int sessionid = audit_get_sessionid(tsk); |
522ed776 | 72 | |
522ed776 MT |
73 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
74 | if (ab) { | |
75 | char name[sizeof(tsk->comm)]; | |
152f497b EP |
76 | |
77 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" | |
f1dc4867 | 78 | " minor=%d comm=", description, pid, uid, |
152f497b | 79 | loginuid, sessionid, major, minor); |
522ed776 MT |
80 | get_task_comm(name, tsk); |
81 | audit_log_untrustedstring(ab, name); | |
82 | audit_log_format(ab, " data="); | |
1e641743 | 83 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
84 | audit_log_end(ab); |
85 | } | |
1e641743 AV |
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 | |
152f497b | 92 | * the current task. @buf->mutex must be locked. |
1e641743 | 93 | */ |
152f497b | 94 | static void tty_audit_buf_push(struct tty_audit_buf *buf) |
1e641743 AV |
95 | { |
96 | if (buf->valid == 0) | |
97 | return; | |
00bff392 XF |
98 | if (audit_enabled == 0) { |
99 | buf->valid = 0; | |
1e641743 | 100 | return; |
00bff392 | 101 | } |
152f497b | 102 | tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid); |
522ed776 MT |
103 | buf->valid = 0; |
104 | } | |
105 | ||
522ed776 MT |
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 | */ | |
112 | void tty_audit_exit(void) | |
113 | { | |
114 | struct tty_audit_buf *buf; | |
115 | ||
522ed776 MT |
116 | buf = current->signal->tty_audit_buf; |
117 | current->signal->tty_audit_buf = NULL; | |
522ed776 MT |
118 | if (!buf) |
119 | return; | |
120 | ||
121 | mutex_lock(&buf->mutex); | |
152f497b | 122 | tty_audit_buf_push(buf); |
522ed776 MT |
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 | */ | |
133 | void tty_audit_fork(struct signal_struct *sig) | |
134 | { | |
522ed776 | 135 | sig->audit_tty = current->signal->audit_tty; |
46e959ea | 136 | sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd; |
522ed776 MT |
137 | } |
138 | ||
1e641743 AV |
139 | /** |
140 | * tty_audit_tiocsti - Log TIOCSTI | |
141 | */ | |
142 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
143 | { | |
144 | struct tty_audit_buf *buf; | |
145 | int major, minor, should_audit; | |
bde02ca8 | 146 | unsigned long flags; |
1e641743 | 147 | |
bde02ca8 | 148 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
1e641743 AV |
149 | should_audit = current->signal->audit_tty; |
150 | buf = current->signal->tty_audit_buf; | |
151 | if (buf) | |
152 | atomic_inc(&buf->count); | |
bde02ca8 | 153 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
1e641743 AV |
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) | |
152f497b | 160 | tty_audit_buf_push(buf); |
1e641743 AV |
161 | mutex_unlock(&buf->mutex); |
162 | tty_audit_buf_put(buf); | |
163 | } | |
164 | ||
165 | if (should_audit && audit_enabled) { | |
e1760bd5 | 166 | kuid_t auid; |
1e641743 AV |
167 | unsigned int sessionid; |
168 | ||
169 | auid = audit_get_loginuid(current); | |
170 | sessionid = audit_get_sessionid(current); | |
152f497b | 171 | tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1); |
1e641743 AV |
172 | } |
173 | } | |
174 | ||
522ed776 | 175 | /** |
152f497b | 176 | * tty_audit_push_current - Flush current's pending audit data |
3c80fe4a | 177 | * |
152f497b | 178 | * Try to lock sighand and get a reference to the tty audit buffer if available. |
3c80fe4a | 179 | * Flush the buffer or return an appropriate error code. |
522ed776 | 180 | */ |
152f497b | 181 | int tty_audit_push_current(void) |
522ed776 | 182 | { |
3c80fe4a | 183 | struct tty_audit_buf *buf = ERR_PTR(-EPERM); |
152f497b | 184 | struct task_struct *tsk = current; |
3c80fe4a | 185 | unsigned long flags; |
522ed776 | 186 | |
3c80fe4a TG |
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); | |
522ed776 MT |
203 | |
204 | mutex_lock(&buf->mutex); | |
152f497b | 205 | tty_audit_buf_push(buf); |
522ed776 MT |
206 | mutex_unlock(&buf->mutex); |
207 | ||
208 | tty_audit_buf_put(buf); | |
3c80fe4a | 209 | return 0; |
522ed776 MT |
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 | */ | |
6c633f27 JS |
219 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, |
220 | unsigned icanon) | |
522ed776 MT |
221 | { |
222 | struct tty_audit_buf *buf, *buf2; | |
bde02ca8 | 223 | unsigned long flags; |
522ed776 MT |
224 | |
225 | buf = NULL; | |
226 | buf2 = NULL; | |
bde02ca8 | 227 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 MT |
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 | } | |
bde02ca8 | 235 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
236 | |
237 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
238 | tty->driver->minor_start + tty->index, | |
6c633f27 | 239 | icanon); |
522ed776 MT |
240 | if (buf2 == NULL) { |
241 | audit_log_lost("out of memory in TTY auditing"); | |
242 | return NULL; | |
243 | } | |
244 | ||
bde02ca8 | 245 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 MT |
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: | |
bde02ca8 | 257 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
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 | */ | |
6b2a3d62 | 268 | void tty_audit_add_data(struct tty_struct *tty, const void *data, |
6c633f27 | 269 | size_t size, unsigned icanon) |
522ed776 MT |
270 | { |
271 | struct tty_audit_buf *buf; | |
272 | int major, minor; | |
46e959ea RGB |
273 | int audit_log_tty_passwd; |
274 | unsigned long flags; | |
522ed776 MT |
275 | |
276 | if (unlikely(size == 0)) | |
277 | return; | |
278 | ||
46e959ea RGB |
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 | ||
41126226 MT |
285 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
286 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
287 | return; | |
288 | ||
6c633f27 | 289 | buf = tty_audit_buf_get(tty, icanon); |
522ed776 MT |
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 | |
6c633f27 | 297 | || buf->icanon != icanon) { |
152f497b | 298 | tty_audit_buf_push(buf); |
522ed776 MT |
299 | buf->major = major; |
300 | buf->minor = minor; | |
6c633f27 | 301 | buf->icanon = icanon; |
522ed776 MT |
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) | |
152f497b | 314 | tty_audit_buf_push(buf); |
522ed776 MT |
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 | */ | |
325 | void tty_audit_push(struct tty_struct *tty) | |
326 | { | |
327 | struct tty_audit_buf *buf; | |
bde02ca8 | 328 | unsigned long flags; |
522ed776 | 329 | |
bde02ca8 | 330 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 | 331 | if (likely(!current->signal->audit_tty)) { |
bde02ca8 | 332 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
333 | return; |
334 | } | |
335 | buf = current->signal->tty_audit_buf; | |
336 | if (buf) | |
337 | atomic_inc(&buf->count); | |
bde02ca8 | 338 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
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) | |
152f497b | 347 | tty_audit_buf_push(buf); |
522ed776 MT |
348 | mutex_unlock(&buf->mutex); |
349 | tty_audit_buf_put(buf); | |
350 | } | |
351 | } |