Commit | Line | Data |
---|---|---|
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> | |
13 | #include <linux/file.h> | |
9f3acc31 | 14 | #include <linux/fdtable.h> |
522ed776 MT |
15 | #include <linux/tty.h> |
16 | ||
17 | struct tty_audit_buf { | |
18 | atomic_t count; | |
19 | struct mutex mutex; /* Protects all data below */ | |
20 | int major, minor; /* The TTY which the data is from */ | |
21 | unsigned icanon:1; | |
22 | size_t valid; | |
23 | unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */ | |
24 | }; | |
25 | ||
26 | static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor, | |
27 | int icanon) | |
28 | { | |
29 | struct tty_audit_buf *buf; | |
30 | ||
66c6ceae | 31 | buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
522ed776 MT |
32 | if (!buf) |
33 | goto err; | |
34 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
35 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); | |
36 | else | |
37 | buf->data = (unsigned char *)__get_free_page(GFP_KERNEL); | |
38 | if (!buf->data) | |
39 | goto err_buf; | |
40 | atomic_set(&buf->count, 1); | |
41 | mutex_init(&buf->mutex); | |
42 | buf->major = major; | |
43 | buf->minor = minor; | |
44 | buf->icanon = icanon; | |
45 | buf->valid = 0; | |
46 | return buf; | |
47 | ||
48 | err_buf: | |
49 | kfree(buf); | |
50 | err: | |
51 | return NULL; | |
52 | } | |
53 | ||
54 | static void tty_audit_buf_free(struct tty_audit_buf *buf) | |
55 | { | |
56 | WARN_ON(buf->valid != 0); | |
57 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
58 | kfree(buf->data); | |
59 | else | |
60 | free_page((unsigned long)buf->data); | |
61 | kfree(buf); | |
62 | } | |
63 | ||
64 | static void tty_audit_buf_put(struct tty_audit_buf *buf) | |
65 | { | |
66 | if (atomic_dec_and_test(&buf->count)) | |
67 | tty_audit_buf_free(buf); | |
68 | } | |
69 | ||
1e641743 AV |
70 | static void tty_audit_log(const char *description, struct task_struct *tsk, |
71 | uid_t loginuid, unsigned sessionid, int major, | |
72 | int minor, unsigned char *data, size_t size) | |
522ed776 MT |
73 | { |
74 | struct audit_buffer *ab; | |
75 | ||
522ed776 MT |
76 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
77 | if (ab) { | |
78 | char name[sizeof(tsk->comm)]; | |
66303bce | 79 | uid_t uid = task_uid(tsk); |
522ed776 | 80 | |
1e641743 AV |
81 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u " |
82 | "major=%d minor=%d comm=", description, | |
66303bce | 83 | tsk->pid, uid, loginuid, sessionid, |
1e641743 | 84 | major, minor); |
522ed776 MT |
85 | get_task_comm(name, tsk); |
86 | audit_log_untrustedstring(ab, name); | |
87 | audit_log_format(ab, " data="); | |
1e641743 | 88 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
89 | audit_log_end(ab); |
90 | } | |
1e641743 AV |
91 | } |
92 | ||
93 | /** | |
94 | * tty_audit_buf_push - Push buffered data out | |
95 | * | |
96 | * Generate an audit message from the contents of @buf, which is owned by | |
97 | * @tsk with @loginuid. @buf->mutex must be locked. | |
98 | */ | |
99 | static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid, | |
100 | unsigned int sessionid, | |
101 | struct tty_audit_buf *buf) | |
102 | { | |
103 | if (buf->valid == 0) | |
104 | return; | |
105 | if (audit_enabled == 0) | |
106 | return; | |
107 | tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor, | |
108 | buf->data, buf->valid); | |
522ed776 MT |
109 | buf->valid = 0; |
110 | } | |
111 | ||
112 | /** | |
113 | * tty_audit_buf_push_current - Push buffered data out | |
114 | * | |
115 | * Generate an audit message from the contents of @buf, which is owned by | |
116 | * the current task. @buf->mutex must be locked. | |
117 | */ | |
118 | static void tty_audit_buf_push_current(struct tty_audit_buf *buf) | |
119 | { | |
4746ec5b EP |
120 | uid_t auid = audit_get_loginuid(current); |
121 | unsigned int sessionid = audit_get_sessionid(current); | |
122 | tty_audit_buf_push(current, auid, sessionid, buf); | |
522ed776 MT |
123 | } |
124 | ||
125 | /** | |
126 | * tty_audit_exit - Handle a task exit | |
127 | * | |
128 | * Make sure all buffered data is written out and deallocate the buffer. | |
129 | * Only needs to be called if current->signal->tty_audit_buf != %NULL. | |
130 | */ | |
131 | void tty_audit_exit(void) | |
132 | { | |
133 | struct tty_audit_buf *buf; | |
134 | ||
135 | spin_lock_irq(¤t->sighand->siglock); | |
136 | buf = current->signal->tty_audit_buf; | |
137 | current->signal->tty_audit_buf = NULL; | |
138 | spin_unlock_irq(¤t->sighand->siglock); | |
139 | if (!buf) | |
140 | return; | |
141 | ||
142 | mutex_lock(&buf->mutex); | |
143 | tty_audit_buf_push_current(buf); | |
144 | mutex_unlock(&buf->mutex); | |
145 | ||
146 | tty_audit_buf_put(buf); | |
147 | } | |
148 | ||
149 | /** | |
150 | * tty_audit_fork - Copy TTY audit state for a new task | |
151 | * | |
152 | * Set up TTY audit state in @sig from current. @sig needs no locking. | |
153 | */ | |
154 | void tty_audit_fork(struct signal_struct *sig) | |
155 | { | |
156 | spin_lock_irq(¤t->sighand->siglock); | |
157 | sig->audit_tty = current->signal->audit_tty; | |
158 | spin_unlock_irq(¤t->sighand->siglock); | |
159 | sig->tty_audit_buf = NULL; | |
160 | } | |
161 | ||
1e641743 AV |
162 | /** |
163 | * tty_audit_tiocsti - Log TIOCSTI | |
164 | */ | |
165 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
166 | { | |
167 | struct tty_audit_buf *buf; | |
168 | int major, minor, should_audit; | |
169 | ||
170 | spin_lock_irq(¤t->sighand->siglock); | |
171 | should_audit = current->signal->audit_tty; | |
172 | buf = current->signal->tty_audit_buf; | |
173 | if (buf) | |
174 | atomic_inc(&buf->count); | |
175 | spin_unlock_irq(¤t->sighand->siglock); | |
176 | ||
177 | major = tty->driver->major; | |
178 | minor = tty->driver->minor_start + tty->index; | |
179 | if (buf) { | |
180 | mutex_lock(&buf->mutex); | |
181 | if (buf->major == major && buf->minor == minor) | |
182 | tty_audit_buf_push_current(buf); | |
183 | mutex_unlock(&buf->mutex); | |
184 | tty_audit_buf_put(buf); | |
185 | } | |
186 | ||
187 | if (should_audit && audit_enabled) { | |
188 | uid_t auid; | |
189 | unsigned int sessionid; | |
190 | ||
191 | auid = audit_get_loginuid(current); | |
192 | sessionid = audit_get_sessionid(current); | |
193 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, | |
194 | minor, &ch, 1); | |
195 | } | |
196 | } | |
197 | ||
522ed776 MT |
198 | /** |
199 | * tty_audit_push_task - Flush task's pending audit data | |
200 | */ | |
2532386f | 201 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
522ed776 MT |
202 | { |
203 | struct tty_audit_buf *buf; | |
204 | ||
205 | spin_lock_irq(&tsk->sighand->siglock); | |
206 | buf = tsk->signal->tty_audit_buf; | |
207 | if (buf) | |
208 | atomic_inc(&buf->count); | |
209 | spin_unlock_irq(&tsk->sighand->siglock); | |
210 | if (!buf) | |
211 | return; | |
212 | ||
213 | mutex_lock(&buf->mutex); | |
4746ec5b | 214 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
215 | mutex_unlock(&buf->mutex); |
216 | ||
217 | tty_audit_buf_put(buf); | |
218 | } | |
219 | ||
220 | /** | |
221 | * tty_audit_buf_get - Get an audit buffer. | |
222 | * | |
223 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL | |
224 | * if TTY auditing is disabled or out of memory. Otherwise, return a new | |
225 | * reference to the buffer. | |
226 | */ | |
227 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) | |
228 | { | |
229 | struct tty_audit_buf *buf, *buf2; | |
230 | ||
231 | buf = NULL; | |
232 | buf2 = NULL; | |
233 | spin_lock_irq(¤t->sighand->siglock); | |
234 | if (likely(!current->signal->audit_tty)) | |
235 | goto out; | |
236 | buf = current->signal->tty_audit_buf; | |
237 | if (buf) { | |
238 | atomic_inc(&buf->count); | |
239 | goto out; | |
240 | } | |
241 | spin_unlock_irq(¤t->sighand->siglock); | |
242 | ||
243 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
244 | tty->driver->minor_start + tty->index, | |
245 | tty->icanon); | |
246 | if (buf2 == NULL) { | |
247 | audit_log_lost("out of memory in TTY auditing"); | |
248 | return NULL; | |
249 | } | |
250 | ||
251 | spin_lock_irq(¤t->sighand->siglock); | |
252 | if (!current->signal->audit_tty) | |
253 | goto out; | |
254 | buf = current->signal->tty_audit_buf; | |
255 | if (!buf) { | |
256 | current->signal->tty_audit_buf = buf2; | |
257 | buf = buf2; | |
258 | buf2 = NULL; | |
259 | } | |
260 | atomic_inc(&buf->count); | |
261 | /* Fall through */ | |
262 | out: | |
263 | spin_unlock_irq(¤t->sighand->siglock); | |
264 | if (buf2) | |
265 | tty_audit_buf_free(buf2); | |
266 | return buf; | |
267 | } | |
268 | ||
269 | /** | |
270 | * tty_audit_add_data - Add data for TTY auditing. | |
271 | * | |
272 | * Audit @data of @size from @tty, if necessary. | |
273 | */ | |
274 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
275 | size_t size) | |
276 | { | |
277 | struct tty_audit_buf *buf; | |
278 | int major, minor; | |
279 | ||
280 | if (unlikely(size == 0)) | |
281 | return; | |
282 | ||
41126226 MT |
283 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
284 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
285 | return; | |
286 | ||
522ed776 MT |
287 | buf = tty_audit_buf_get(tty); |
288 | if (!buf) | |
289 | return; | |
290 | ||
291 | mutex_lock(&buf->mutex); | |
292 | major = tty->driver->major; | |
293 | minor = tty->driver->minor_start + tty->index; | |
294 | if (buf->major != major || buf->minor != minor | |
295 | || buf->icanon != tty->icanon) { | |
296 | tty_audit_buf_push_current(buf); | |
297 | buf->major = major; | |
298 | buf->minor = minor; | |
299 | buf->icanon = tty->icanon; | |
300 | } | |
301 | do { | |
302 | size_t run; | |
303 | ||
304 | run = N_TTY_BUF_SIZE - buf->valid; | |
305 | if (run > size) | |
306 | run = size; | |
307 | memcpy(buf->data + buf->valid, data, run); | |
308 | buf->valid += run; | |
309 | data += run; | |
310 | size -= run; | |
311 | if (buf->valid == N_TTY_BUF_SIZE) | |
312 | tty_audit_buf_push_current(buf); | |
313 | } while (size != 0); | |
314 | mutex_unlock(&buf->mutex); | |
315 | tty_audit_buf_put(buf); | |
316 | } | |
317 | ||
318 | /** | |
319 | * tty_audit_push - Push buffered data out | |
320 | * | |
321 | * Make sure no audit data is pending for @tty on the current process. | |
322 | */ | |
323 | void tty_audit_push(struct tty_struct *tty) | |
324 | { | |
325 | struct tty_audit_buf *buf; | |
326 | ||
327 | spin_lock_irq(¤t->sighand->siglock); | |
328 | if (likely(!current->signal->audit_tty)) { | |
329 | spin_unlock_irq(¤t->sighand->siglock); | |
330 | return; | |
331 | } | |
332 | buf = current->signal->tty_audit_buf; | |
333 | if (buf) | |
334 | atomic_inc(&buf->count); | |
335 | spin_unlock_irq(¤t->sighand->siglock); | |
336 | ||
337 | if (buf) { | |
338 | int major, minor; | |
339 | ||
340 | major = tty->driver->major; | |
341 | minor = tty->driver->minor_start + tty->index; | |
342 | mutex_lock(&buf->mutex); | |
343 | if (buf->major == major && buf->minor == minor) | |
344 | tty_audit_buf_push_current(buf); | |
345 | mutex_unlock(&buf->mutex); | |
346 | tty_audit_buf_put(buf); | |
347 | } | |
348 | } |