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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> | |
522ed776 MT |
13 | #include <linux/tty.h> |
14 | ||
15 | struct tty_audit_buf { | |
16 | atomic_t count; | |
17 | struct mutex mutex; /* Protects all data below */ | |
18 | int major, minor; /* The TTY which the data is from */ | |
19 | unsigned icanon:1; | |
20 | size_t valid; | |
21 | unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */ | |
22 | }; | |
23 | ||
24 | static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor, | |
25 | int icanon) | |
26 | { | |
27 | struct tty_audit_buf *buf; | |
28 | ||
66c6ceae | 29 | buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
522ed776 MT |
30 | if (!buf) |
31 | goto err; | |
c481c707 | 32 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
522ed776 MT |
33 | if (!buf->data) |
34 | goto err_buf; | |
35 | atomic_set(&buf->count, 1); | |
36 | mutex_init(&buf->mutex); | |
37 | buf->major = major; | |
38 | buf->minor = minor; | |
39 | buf->icanon = icanon; | |
40 | buf->valid = 0; | |
41 | return buf; | |
42 | ||
43 | err_buf: | |
44 | kfree(buf); | |
45 | err: | |
46 | return NULL; | |
47 | } | |
48 | ||
49 | static void tty_audit_buf_free(struct tty_audit_buf *buf) | |
50 | { | |
51 | WARN_ON(buf->valid != 0); | |
c481c707 | 52 | kfree(buf->data); |
522ed776 MT |
53 | kfree(buf); |
54 | } | |
55 | ||
56 | static void tty_audit_buf_put(struct tty_audit_buf *buf) | |
57 | { | |
58 | if (atomic_dec_and_test(&buf->count)) | |
59 | tty_audit_buf_free(buf); | |
60 | } | |
61 | ||
1e641743 AV |
62 | static void tty_audit_log(const char *description, struct task_struct *tsk, |
63 | uid_t loginuid, unsigned sessionid, int major, | |
64 | int minor, unsigned char *data, size_t size) | |
522ed776 MT |
65 | { |
66 | struct audit_buffer *ab; | |
67 | ||
522ed776 MT |
68 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
69 | if (ab) { | |
70 | char name[sizeof(tsk->comm)]; | |
66303bce | 71 | uid_t uid = task_uid(tsk); |
522ed776 | 72 | |
1e641743 AV |
73 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u " |
74 | "major=%d minor=%d comm=", description, | |
66303bce | 75 | tsk->pid, uid, loginuid, sessionid, |
1e641743 | 76 | major, minor); |
522ed776 MT |
77 | get_task_comm(name, tsk); |
78 | audit_log_untrustedstring(ab, name); | |
79 | audit_log_format(ab, " data="); | |
1e641743 | 80 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
81 | audit_log_end(ab); |
82 | } | |
1e641743 AV |
83 | } |
84 | ||
85 | /** | |
86 | * tty_audit_buf_push - Push buffered data out | |
87 | * | |
88 | * Generate an audit message from the contents of @buf, which is owned by | |
89 | * @tsk with @loginuid. @buf->mutex must be locked. | |
90 | */ | |
91 | static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid, | |
92 | unsigned int sessionid, | |
93 | struct tty_audit_buf *buf) | |
94 | { | |
95 | if (buf->valid == 0) | |
96 | return; | |
97 | if (audit_enabled == 0) | |
98 | return; | |
99 | tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor, | |
100 | buf->data, buf->valid); | |
522ed776 MT |
101 | buf->valid = 0; |
102 | } | |
103 | ||
104 | /** | |
105 | * tty_audit_buf_push_current - Push buffered data out | |
106 | * | |
107 | * Generate an audit message from the contents of @buf, which is owned by | |
108 | * the current task. @buf->mutex must be locked. | |
109 | */ | |
110 | static void tty_audit_buf_push_current(struct tty_audit_buf *buf) | |
111 | { | |
4746ec5b EP |
112 | uid_t auid = audit_get_loginuid(current); |
113 | unsigned int sessionid = audit_get_sessionid(current); | |
114 | tty_audit_buf_push(current, auid, sessionid, buf); | |
522ed776 MT |
115 | } |
116 | ||
117 | /** | |
118 | * tty_audit_exit - Handle a task exit | |
119 | * | |
120 | * Make sure all buffered data is written out and deallocate the buffer. | |
121 | * Only needs to be called if current->signal->tty_audit_buf != %NULL. | |
122 | */ | |
123 | void tty_audit_exit(void) | |
124 | { | |
125 | struct tty_audit_buf *buf; | |
126 | ||
127 | spin_lock_irq(¤t->sighand->siglock); | |
128 | buf = current->signal->tty_audit_buf; | |
129 | current->signal->tty_audit_buf = NULL; | |
130 | spin_unlock_irq(¤t->sighand->siglock); | |
131 | if (!buf) | |
132 | return; | |
133 | ||
134 | mutex_lock(&buf->mutex); | |
135 | tty_audit_buf_push_current(buf); | |
136 | mutex_unlock(&buf->mutex); | |
137 | ||
138 | tty_audit_buf_put(buf); | |
139 | } | |
140 | ||
141 | /** | |
142 | * tty_audit_fork - Copy TTY audit state for a new task | |
143 | * | |
144 | * Set up TTY audit state in @sig from current. @sig needs no locking. | |
145 | */ | |
146 | void tty_audit_fork(struct signal_struct *sig) | |
147 | { | |
148 | spin_lock_irq(¤t->sighand->siglock); | |
149 | sig->audit_tty = current->signal->audit_tty; | |
150 | spin_unlock_irq(¤t->sighand->siglock); | |
522ed776 MT |
151 | } |
152 | ||
1e641743 AV |
153 | /** |
154 | * tty_audit_tiocsti - Log TIOCSTI | |
155 | */ | |
156 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
157 | { | |
158 | struct tty_audit_buf *buf; | |
159 | int major, minor, should_audit; | |
160 | ||
161 | spin_lock_irq(¤t->sighand->siglock); | |
162 | should_audit = current->signal->audit_tty; | |
163 | buf = current->signal->tty_audit_buf; | |
164 | if (buf) | |
165 | atomic_inc(&buf->count); | |
166 | spin_unlock_irq(¤t->sighand->siglock); | |
167 | ||
168 | major = tty->driver->major; | |
169 | minor = tty->driver->minor_start + tty->index; | |
170 | if (buf) { | |
171 | mutex_lock(&buf->mutex); | |
172 | if (buf->major == major && buf->minor == minor) | |
173 | tty_audit_buf_push_current(buf); | |
174 | mutex_unlock(&buf->mutex); | |
175 | tty_audit_buf_put(buf); | |
176 | } | |
177 | ||
178 | if (should_audit && audit_enabled) { | |
179 | uid_t auid; | |
180 | unsigned int sessionid; | |
181 | ||
182 | auid = audit_get_loginuid(current); | |
183 | sessionid = audit_get_sessionid(current); | |
184 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, | |
185 | minor, &ch, 1); | |
186 | } | |
187 | } | |
188 | ||
522ed776 MT |
189 | /** |
190 | * tty_audit_push_task - Flush task's pending audit data | |
191 | */ | |
2532386f | 192 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
522ed776 MT |
193 | { |
194 | struct tty_audit_buf *buf; | |
195 | ||
196 | spin_lock_irq(&tsk->sighand->siglock); | |
197 | buf = tsk->signal->tty_audit_buf; | |
198 | if (buf) | |
199 | atomic_inc(&buf->count); | |
200 | spin_unlock_irq(&tsk->sighand->siglock); | |
201 | if (!buf) | |
202 | return; | |
203 | ||
204 | mutex_lock(&buf->mutex); | |
4746ec5b | 205 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
206 | mutex_unlock(&buf->mutex); |
207 | ||
208 | tty_audit_buf_put(buf); | |
209 | } | |
210 | ||
211 | /** | |
212 | * tty_audit_buf_get - Get an audit buffer. | |
213 | * | |
214 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL | |
215 | * if TTY auditing is disabled or out of memory. Otherwise, return a new | |
216 | * reference to the buffer. | |
217 | */ | |
218 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) | |
219 | { | |
220 | struct tty_audit_buf *buf, *buf2; | |
221 | ||
222 | buf = NULL; | |
223 | buf2 = NULL; | |
224 | spin_lock_irq(¤t->sighand->siglock); | |
225 | if (likely(!current->signal->audit_tty)) | |
226 | goto out; | |
227 | buf = current->signal->tty_audit_buf; | |
228 | if (buf) { | |
229 | atomic_inc(&buf->count); | |
230 | goto out; | |
231 | } | |
232 | spin_unlock_irq(¤t->sighand->siglock); | |
233 | ||
234 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
235 | tty->driver->minor_start + tty->index, | |
236 | tty->icanon); | |
237 | if (buf2 == NULL) { | |
238 | audit_log_lost("out of memory in TTY auditing"); | |
239 | return NULL; | |
240 | } | |
241 | ||
242 | spin_lock_irq(¤t->sighand->siglock); | |
243 | if (!current->signal->audit_tty) | |
244 | goto out; | |
245 | buf = current->signal->tty_audit_buf; | |
246 | if (!buf) { | |
247 | current->signal->tty_audit_buf = buf2; | |
248 | buf = buf2; | |
249 | buf2 = NULL; | |
250 | } | |
251 | atomic_inc(&buf->count); | |
252 | /* Fall through */ | |
253 | out: | |
254 | spin_unlock_irq(¤t->sighand->siglock); | |
255 | if (buf2) | |
256 | tty_audit_buf_free(buf2); | |
257 | return buf; | |
258 | } | |
259 | ||
260 | /** | |
261 | * tty_audit_add_data - Add data for TTY auditing. | |
262 | * | |
263 | * Audit @data of @size from @tty, if necessary. | |
264 | */ | |
265 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
266 | size_t size) | |
267 | { | |
268 | struct tty_audit_buf *buf; | |
269 | int major, minor; | |
270 | ||
271 | if (unlikely(size == 0)) | |
272 | return; | |
273 | ||
41126226 MT |
274 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
275 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
276 | return; | |
277 | ||
522ed776 MT |
278 | buf = tty_audit_buf_get(tty); |
279 | if (!buf) | |
280 | return; | |
281 | ||
282 | mutex_lock(&buf->mutex); | |
283 | major = tty->driver->major; | |
284 | minor = tty->driver->minor_start + tty->index; | |
285 | if (buf->major != major || buf->minor != minor | |
286 | || buf->icanon != tty->icanon) { | |
287 | tty_audit_buf_push_current(buf); | |
288 | buf->major = major; | |
289 | buf->minor = minor; | |
290 | buf->icanon = tty->icanon; | |
291 | } | |
292 | do { | |
293 | size_t run; | |
294 | ||
295 | run = N_TTY_BUF_SIZE - buf->valid; | |
296 | if (run > size) | |
297 | run = size; | |
298 | memcpy(buf->data + buf->valid, data, run); | |
299 | buf->valid += run; | |
300 | data += run; | |
301 | size -= run; | |
302 | if (buf->valid == N_TTY_BUF_SIZE) | |
303 | tty_audit_buf_push_current(buf); | |
304 | } while (size != 0); | |
305 | mutex_unlock(&buf->mutex); | |
306 | tty_audit_buf_put(buf); | |
307 | } | |
308 | ||
309 | /** | |
310 | * tty_audit_push - Push buffered data out | |
311 | * | |
312 | * Make sure no audit data is pending for @tty on the current process. | |
313 | */ | |
314 | void tty_audit_push(struct tty_struct *tty) | |
315 | { | |
316 | struct tty_audit_buf *buf; | |
317 | ||
318 | spin_lock_irq(¤t->sighand->siglock); | |
319 | if (likely(!current->signal->audit_tty)) { | |
320 | spin_unlock_irq(¤t->sighand->siglock); | |
321 | return; | |
322 | } | |
323 | buf = current->signal->tty_audit_buf; | |
324 | if (buf) | |
325 | atomic_inc(&buf->count); | |
326 | spin_unlock_irq(¤t->sighand->siglock); | |
327 | ||
328 | if (buf) { | |
329 | int major, minor; | |
330 | ||
331 | major = tty->driver->major; | |
332 | minor = tty->driver->minor_start + tty->index; | |
333 | mutex_lock(&buf->mutex); | |
334 | if (buf->major == major && buf->minor == minor) | |
335 | tty_audit_buf_push_current(buf); | |
336 | mutex_unlock(&buf->mutex); | |
337 | tty_audit_buf_put(buf); | |
338 | } | |
339 | } |