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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); | |
151 | sig->tty_audit_buf = NULL; | |
152 | } | |
153 | ||
1e641743 AV |
154 | /** |
155 | * tty_audit_tiocsti - Log TIOCSTI | |
156 | */ | |
157 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
158 | { | |
159 | struct tty_audit_buf *buf; | |
160 | int major, minor, should_audit; | |
161 | ||
162 | spin_lock_irq(¤t->sighand->siglock); | |
163 | should_audit = current->signal->audit_tty; | |
164 | buf = current->signal->tty_audit_buf; | |
165 | if (buf) | |
166 | atomic_inc(&buf->count); | |
167 | spin_unlock_irq(¤t->sighand->siglock); | |
168 | ||
169 | major = tty->driver->major; | |
170 | minor = tty->driver->minor_start + tty->index; | |
171 | if (buf) { | |
172 | mutex_lock(&buf->mutex); | |
173 | if (buf->major == major && buf->minor == minor) | |
174 | tty_audit_buf_push_current(buf); | |
175 | mutex_unlock(&buf->mutex); | |
176 | tty_audit_buf_put(buf); | |
177 | } | |
178 | ||
179 | if (should_audit && audit_enabled) { | |
180 | uid_t auid; | |
181 | unsigned int sessionid; | |
182 | ||
183 | auid = audit_get_loginuid(current); | |
184 | sessionid = audit_get_sessionid(current); | |
185 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, | |
186 | minor, &ch, 1); | |
187 | } | |
188 | } | |
189 | ||
522ed776 MT |
190 | /** |
191 | * tty_audit_push_task - Flush task's pending audit data | |
192 | */ | |
2532386f | 193 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
522ed776 MT |
194 | { |
195 | struct tty_audit_buf *buf; | |
196 | ||
197 | spin_lock_irq(&tsk->sighand->siglock); | |
198 | buf = tsk->signal->tty_audit_buf; | |
199 | if (buf) | |
200 | atomic_inc(&buf->count); | |
201 | spin_unlock_irq(&tsk->sighand->siglock); | |
202 | if (!buf) | |
203 | return; | |
204 | ||
205 | mutex_lock(&buf->mutex); | |
4746ec5b | 206 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
207 | mutex_unlock(&buf->mutex); |
208 | ||
209 | tty_audit_buf_put(buf); | |
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 | */ | |
219 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) | |
220 | { | |
221 | struct tty_audit_buf *buf, *buf2; | |
222 | ||
223 | buf = NULL; | |
224 | buf2 = NULL; | |
225 | spin_lock_irq(¤t->sighand->siglock); | |
226 | if (likely(!current->signal->audit_tty)) | |
227 | goto out; | |
228 | buf = current->signal->tty_audit_buf; | |
229 | if (buf) { | |
230 | atomic_inc(&buf->count); | |
231 | goto out; | |
232 | } | |
233 | spin_unlock_irq(¤t->sighand->siglock); | |
234 | ||
235 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
236 | tty->driver->minor_start + tty->index, | |
237 | tty->icanon); | |
238 | if (buf2 == NULL) { | |
239 | audit_log_lost("out of memory in TTY auditing"); | |
240 | return NULL; | |
241 | } | |
242 | ||
243 | spin_lock_irq(¤t->sighand->siglock); | |
244 | if (!current->signal->audit_tty) | |
245 | goto out; | |
246 | buf = current->signal->tty_audit_buf; | |
247 | if (!buf) { | |
248 | current->signal->tty_audit_buf = buf2; | |
249 | buf = buf2; | |
250 | buf2 = NULL; | |
251 | } | |
252 | atomic_inc(&buf->count); | |
253 | /* Fall through */ | |
254 | out: | |
255 | spin_unlock_irq(¤t->sighand->siglock); | |
256 | if (buf2) | |
257 | tty_audit_buf_free(buf2); | |
258 | return buf; | |
259 | } | |
260 | ||
261 | /** | |
262 | * tty_audit_add_data - Add data for TTY auditing. | |
263 | * | |
264 | * Audit @data of @size from @tty, if necessary. | |
265 | */ | |
266 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
267 | size_t size) | |
268 | { | |
269 | struct tty_audit_buf *buf; | |
270 | int major, minor; | |
271 | ||
272 | if (unlikely(size == 0)) | |
273 | return; | |
274 | ||
41126226 MT |
275 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
276 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
277 | return; | |
278 | ||
522ed776 MT |
279 | buf = tty_audit_buf_get(tty); |
280 | if (!buf) | |
281 | return; | |
282 | ||
283 | mutex_lock(&buf->mutex); | |
284 | major = tty->driver->major; | |
285 | minor = tty->driver->minor_start + tty->index; | |
286 | if (buf->major != major || buf->minor != minor | |
287 | || buf->icanon != tty->icanon) { | |
288 | tty_audit_buf_push_current(buf); | |
289 | buf->major = major; | |
290 | buf->minor = minor; | |
291 | buf->icanon = tty->icanon; | |
292 | } | |
293 | do { | |
294 | size_t run; | |
295 | ||
296 | run = N_TTY_BUF_SIZE - buf->valid; | |
297 | if (run > size) | |
298 | run = size; | |
299 | memcpy(buf->data + buf->valid, data, run); | |
300 | buf->valid += run; | |
301 | data += run; | |
302 | size -= run; | |
303 | if (buf->valid == N_TTY_BUF_SIZE) | |
304 | tty_audit_buf_push_current(buf); | |
305 | } while (size != 0); | |
306 | mutex_unlock(&buf->mutex); | |
307 | tty_audit_buf_put(buf); | |
308 | } | |
309 | ||
310 | /** | |
311 | * tty_audit_push - Push buffered data out | |
312 | * | |
313 | * Make sure no audit data is pending for @tty on the current process. | |
314 | */ | |
315 | void tty_audit_push(struct tty_struct *tty) | |
316 | { | |
317 | struct tty_audit_buf *buf; | |
318 | ||
319 | spin_lock_irq(¤t->sighand->siglock); | |
320 | if (likely(!current->signal->audit_tty)) { | |
321 | spin_unlock_irq(¤t->sighand->siglock); | |
322 | return; | |
323 | } | |
324 | buf = current->signal->tty_audit_buf; | |
325 | if (buf) | |
326 | atomic_inc(&buf->count); | |
327 | spin_unlock_irq(¤t->sighand->siglock); | |
328 | ||
329 | if (buf) { | |
330 | int major, minor; | |
331 | ||
332 | major = tty->driver->major; | |
333 | minor = tty->driver->minor_start + tty->index; | |
334 | mutex_lock(&buf->mutex); | |
335 | if (buf->major == major && buf->minor == minor) | |
336 | tty_audit_buf_push_current(buf); | |
337 | mutex_unlock(&buf->mutex); | |
338 | tty_audit_buf_put(buf); | |
339 | } | |
340 | } |