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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; | |
32 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
33 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); | |
34 | else | |
35 | buf->data = (unsigned char *)__get_free_page(GFP_KERNEL); | |
36 | if (!buf->data) | |
37 | goto err_buf; | |
38 | atomic_set(&buf->count, 1); | |
39 | mutex_init(&buf->mutex); | |
40 | buf->major = major; | |
41 | buf->minor = minor; | |
42 | buf->icanon = icanon; | |
43 | buf->valid = 0; | |
44 | return buf; | |
45 | ||
46 | err_buf: | |
47 | kfree(buf); | |
48 | err: | |
49 | return NULL; | |
50 | } | |
51 | ||
52 | static void tty_audit_buf_free(struct tty_audit_buf *buf) | |
53 | { | |
54 | WARN_ON(buf->valid != 0); | |
55 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
56 | kfree(buf->data); | |
57 | else | |
58 | free_page((unsigned long)buf->data); | |
59 | kfree(buf); | |
60 | } | |
61 | ||
62 | static void tty_audit_buf_put(struct tty_audit_buf *buf) | |
63 | { | |
64 | if (atomic_dec_and_test(&buf->count)) | |
65 | tty_audit_buf_free(buf); | |
66 | } | |
67 | ||
1e641743 AV |
68 | static void tty_audit_log(const char *description, struct task_struct *tsk, |
69 | uid_t loginuid, unsigned sessionid, int major, | |
70 | int minor, unsigned char *data, size_t size) | |
522ed776 MT |
71 | { |
72 | struct audit_buffer *ab; | |
73 | ||
522ed776 MT |
74 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
75 | if (ab) { | |
76 | char name[sizeof(tsk->comm)]; | |
66303bce | 77 | uid_t uid = task_uid(tsk); |
522ed776 | 78 | |
1e641743 AV |
79 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u " |
80 | "major=%d minor=%d comm=", description, | |
66303bce | 81 | tsk->pid, uid, loginuid, sessionid, |
1e641743 | 82 | major, minor); |
522ed776 MT |
83 | get_task_comm(name, tsk); |
84 | audit_log_untrustedstring(ab, name); | |
85 | audit_log_format(ab, " data="); | |
1e641743 | 86 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
87 | audit_log_end(ab); |
88 | } | |
1e641743 AV |
89 | } |
90 | ||
91 | /** | |
92 | * tty_audit_buf_push - Push buffered data out | |
93 | * | |
94 | * Generate an audit message from the contents of @buf, which is owned by | |
95 | * @tsk with @loginuid. @buf->mutex must be locked. | |
96 | */ | |
97 | static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid, | |
98 | unsigned int sessionid, | |
99 | struct tty_audit_buf *buf) | |
100 | { | |
101 | if (buf->valid == 0) | |
102 | return; | |
103 | if (audit_enabled == 0) | |
104 | return; | |
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 | { | |
4746ec5b EP |
118 | uid_t auid = audit_get_loginuid(current); |
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); | |
157 | sig->tty_audit_buf = NULL; | |
158 | } | |
159 | ||
1e641743 AV |
160 | /** |
161 | * tty_audit_tiocsti - Log TIOCSTI | |
162 | */ | |
163 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
164 | { | |
165 | struct tty_audit_buf *buf; | |
166 | int major, minor, should_audit; | |
167 | ||
168 | spin_lock_irq(¤t->sighand->siglock); | |
169 | should_audit = current->signal->audit_tty; | |
170 | buf = current->signal->tty_audit_buf; | |
171 | if (buf) | |
172 | atomic_inc(&buf->count); | |
173 | spin_unlock_irq(¤t->sighand->siglock); | |
174 | ||
175 | major = tty->driver->major; | |
176 | minor = tty->driver->minor_start + tty->index; | |
177 | if (buf) { | |
178 | mutex_lock(&buf->mutex); | |
179 | if (buf->major == major && buf->minor == minor) | |
180 | tty_audit_buf_push_current(buf); | |
181 | mutex_unlock(&buf->mutex); | |
182 | tty_audit_buf_put(buf); | |
183 | } | |
184 | ||
185 | if (should_audit && audit_enabled) { | |
186 | uid_t auid; | |
187 | unsigned int sessionid; | |
188 | ||
189 | auid = audit_get_loginuid(current); | |
190 | sessionid = audit_get_sessionid(current); | |
191 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, | |
192 | minor, &ch, 1); | |
193 | } | |
194 | } | |
195 | ||
522ed776 MT |
196 | /** |
197 | * tty_audit_push_task - Flush task's pending audit data | |
198 | */ | |
2532386f | 199 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
522ed776 MT |
200 | { |
201 | struct tty_audit_buf *buf; | |
202 | ||
203 | spin_lock_irq(&tsk->sighand->siglock); | |
204 | buf = tsk->signal->tty_audit_buf; | |
205 | if (buf) | |
206 | atomic_inc(&buf->count); | |
207 | spin_unlock_irq(&tsk->sighand->siglock); | |
208 | if (!buf) | |
209 | return; | |
210 | ||
211 | mutex_lock(&buf->mutex); | |
4746ec5b | 212 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
213 | mutex_unlock(&buf->mutex); |
214 | ||
215 | tty_audit_buf_put(buf); | |
216 | } | |
217 | ||
218 | /** | |
219 | * tty_audit_buf_get - Get an audit buffer. | |
220 | * | |
221 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL | |
222 | * if TTY auditing is disabled or out of memory. Otherwise, return a new | |
223 | * reference to the buffer. | |
224 | */ | |
225 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) | |
226 | { | |
227 | struct tty_audit_buf *buf, *buf2; | |
228 | ||
229 | buf = NULL; | |
230 | buf2 = NULL; | |
231 | spin_lock_irq(¤t->sighand->siglock); | |
232 | if (likely(!current->signal->audit_tty)) | |
233 | goto out; | |
234 | buf = current->signal->tty_audit_buf; | |
235 | if (buf) { | |
236 | atomic_inc(&buf->count); | |
237 | goto out; | |
238 | } | |
239 | spin_unlock_irq(¤t->sighand->siglock); | |
240 | ||
241 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
242 | tty->driver->minor_start + tty->index, | |
243 | tty->icanon); | |
244 | if (buf2 == NULL) { | |
245 | audit_log_lost("out of memory in TTY auditing"); | |
246 | return NULL; | |
247 | } | |
248 | ||
249 | spin_lock_irq(¤t->sighand->siglock); | |
250 | if (!current->signal->audit_tty) | |
251 | goto out; | |
252 | buf = current->signal->tty_audit_buf; | |
253 | if (!buf) { | |
254 | current->signal->tty_audit_buf = buf2; | |
255 | buf = buf2; | |
256 | buf2 = NULL; | |
257 | } | |
258 | atomic_inc(&buf->count); | |
259 | /* Fall through */ | |
260 | out: | |
261 | spin_unlock_irq(¤t->sighand->siglock); | |
262 | if (buf2) | |
263 | tty_audit_buf_free(buf2); | |
264 | return buf; | |
265 | } | |
266 | ||
267 | /** | |
268 | * tty_audit_add_data - Add data for TTY auditing. | |
269 | * | |
270 | * Audit @data of @size from @tty, if necessary. | |
271 | */ | |
272 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
273 | size_t size) | |
274 | { | |
275 | struct tty_audit_buf *buf; | |
276 | int major, minor; | |
277 | ||
278 | if (unlikely(size == 0)) | |
279 | return; | |
280 | ||
41126226 MT |
281 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
282 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
283 | return; | |
284 | ||
522ed776 MT |
285 | buf = tty_audit_buf_get(tty); |
286 | if (!buf) | |
287 | return; | |
288 | ||
289 | mutex_lock(&buf->mutex); | |
290 | major = tty->driver->major; | |
291 | minor = tty->driver->minor_start + tty->index; | |
292 | if (buf->major != major || buf->minor != minor | |
293 | || buf->icanon != tty->icanon) { | |
294 | tty_audit_buf_push_current(buf); | |
295 | buf->major = major; | |
296 | buf->minor = minor; | |
297 | buf->icanon = tty->icanon; | |
298 | } | |
299 | do { | |
300 | size_t run; | |
301 | ||
302 | run = N_TTY_BUF_SIZE - buf->valid; | |
303 | if (run > size) | |
304 | run = size; | |
305 | memcpy(buf->data + buf->valid, data, run); | |
306 | buf->valid += run; | |
307 | data += run; | |
308 | size -= run; | |
309 | if (buf->valid == N_TTY_BUF_SIZE) | |
310 | tty_audit_buf_push_current(buf); | |
311 | } while (size != 0); | |
312 | mutex_unlock(&buf->mutex); | |
313 | tty_audit_buf_put(buf); | |
314 | } | |
315 | ||
316 | /** | |
317 | * tty_audit_push - Push buffered data out | |
318 | * | |
319 | * Make sure no audit data is pending for @tty on the current process. | |
320 | */ | |
321 | void tty_audit_push(struct tty_struct *tty) | |
322 | { | |
323 | struct tty_audit_buf *buf; | |
324 | ||
325 | spin_lock_irq(¤t->sighand->siglock); | |
326 | if (likely(!current->signal->audit_tty)) { | |
327 | spin_unlock_irq(¤t->sighand->siglock); | |
328 | return; | |
329 | } | |
330 | buf = current->signal->tty_audit_buf; | |
331 | if (buf) | |
332 | atomic_inc(&buf->count); | |
333 | spin_unlock_irq(¤t->sighand->siglock); | |
334 | ||
335 | if (buf) { | |
336 | int major, minor; | |
337 | ||
338 | major = tty->driver->major; | |
339 | minor = tty->driver->minor_start + tty->index; | |
340 | mutex_lock(&buf->mutex); | |
341 | if (buf->major == major && buf->minor == minor) | |
342 | tty_audit_buf_push_current(buf); | |
343 | mutex_unlock(&buf->mutex); | |
344 | tty_audit_buf_put(buf); | |
345 | } | |
346 | } |