Commit | Line | Data |
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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 | ||
a75c9b09 | 25 | static struct tty_audit_buf *tty_audit_buf_alloc(void) |
522ed776 MT |
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); | |
a75c9b09 PH |
37 | buf->major = 0; |
38 | buf->minor = 0; | |
39 | buf->icanon = 0; | |
522ed776 MT |
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 | ||
152f497b EP |
62 | static void tty_audit_log(const char *description, int major, int minor, |
63 | unsigned char *data, size_t size) | |
522ed776 MT |
64 | { |
65 | struct audit_buffer *ab; | |
152f497b | 66 | struct task_struct *tsk = current; |
f1dc4867 | 67 | pid_t pid = task_pid_nr(tsk); |
152f497b EP |
68 | uid_t uid = from_kuid(&init_user_ns, task_uid(tsk)); |
69 | uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk)); | |
4440e854 | 70 | unsigned int sessionid = audit_get_sessionid(tsk); |
522ed776 | 71 | |
522ed776 MT |
72 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
73 | if (ab) { | |
74 | char name[sizeof(tsk->comm)]; | |
152f497b EP |
75 | |
76 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" | |
f1dc4867 | 77 | " minor=%d comm=", description, pid, uid, |
152f497b | 78 | loginuid, sessionid, major, minor); |
522ed776 MT |
79 | get_task_comm(name, tsk); |
80 | audit_log_untrustedstring(ab, name); | |
81 | audit_log_format(ab, " data="); | |
1e641743 | 82 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
83 | audit_log_end(ab); |
84 | } | |
1e641743 AV |
85 | } |
86 | ||
87 | /** | |
88 | * tty_audit_buf_push - Push buffered data out | |
89 | * | |
90 | * Generate an audit message from the contents of @buf, which is owned by | |
152f497b | 91 | * the current task. @buf->mutex must be locked. |
1e641743 | 92 | */ |
152f497b | 93 | static void tty_audit_buf_push(struct tty_audit_buf *buf) |
1e641743 AV |
94 | { |
95 | if (buf->valid == 0) | |
96 | return; | |
00bff392 XF |
97 | if (audit_enabled == 0) { |
98 | buf->valid = 0; | |
1e641743 | 99 | return; |
00bff392 | 100 | } |
152f497b | 101 | tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid); |
522ed776 MT |
102 | buf->valid = 0; |
103 | } | |
104 | ||
522ed776 MT |
105 | /** |
106 | * tty_audit_exit - Handle a task exit | |
107 | * | |
108 | * Make sure all buffered data is written out and deallocate the buffer. | |
109 | * Only needs to be called if current->signal->tty_audit_buf != %NULL. | |
110 | */ | |
111 | void tty_audit_exit(void) | |
112 | { | |
113 | struct tty_audit_buf *buf; | |
114 | ||
522ed776 MT |
115 | buf = current->signal->tty_audit_buf; |
116 | current->signal->tty_audit_buf = NULL; | |
522ed776 MT |
117 | if (!buf) |
118 | return; | |
119 | ||
120 | mutex_lock(&buf->mutex); | |
152f497b | 121 | tty_audit_buf_push(buf); |
522ed776 MT |
122 | mutex_unlock(&buf->mutex); |
123 | ||
124 | tty_audit_buf_put(buf); | |
125 | } | |
126 | ||
127 | /** | |
128 | * tty_audit_fork - Copy TTY audit state for a new task | |
129 | * | |
130 | * Set up TTY audit state in @sig from current. @sig needs no locking. | |
131 | */ | |
132 | void tty_audit_fork(struct signal_struct *sig) | |
133 | { | |
522ed776 | 134 | sig->audit_tty = current->signal->audit_tty; |
46e959ea | 135 | sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd; |
522ed776 MT |
136 | } |
137 | ||
1e641743 AV |
138 | /** |
139 | * tty_audit_tiocsti - Log TIOCSTI | |
140 | */ | |
141 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
142 | { | |
143 | struct tty_audit_buf *buf; | |
144 | int major, minor, should_audit; | |
bde02ca8 | 145 | unsigned long flags; |
1e641743 | 146 | |
bde02ca8 | 147 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
1e641743 AV |
148 | should_audit = current->signal->audit_tty; |
149 | buf = current->signal->tty_audit_buf; | |
150 | if (buf) | |
151 | atomic_inc(&buf->count); | |
bde02ca8 | 152 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
1e641743 AV |
153 | |
154 | major = tty->driver->major; | |
155 | minor = tty->driver->minor_start + tty->index; | |
156 | if (buf) { | |
157 | mutex_lock(&buf->mutex); | |
158 | if (buf->major == major && buf->minor == minor) | |
152f497b | 159 | tty_audit_buf_push(buf); |
1e641743 AV |
160 | mutex_unlock(&buf->mutex); |
161 | tty_audit_buf_put(buf); | |
162 | } | |
163 | ||
164 | if (should_audit && audit_enabled) { | |
e1760bd5 | 165 | kuid_t auid; |
1e641743 AV |
166 | unsigned int sessionid; |
167 | ||
168 | auid = audit_get_loginuid(current); | |
169 | sessionid = audit_get_sessionid(current); | |
152f497b | 170 | tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1); |
1e641743 AV |
171 | } |
172 | } | |
173 | ||
522ed776 | 174 | /** |
152f497b | 175 | * tty_audit_push_current - Flush current's pending audit data |
3c80fe4a | 176 | * |
152f497b | 177 | * Try to lock sighand and get a reference to the tty audit buffer if available. |
3c80fe4a | 178 | * Flush the buffer or return an appropriate error code. |
522ed776 | 179 | */ |
152f497b | 180 | int tty_audit_push_current(void) |
522ed776 | 181 | { |
3c80fe4a TG |
182 | struct tty_audit_buf *buf = ERR_PTR(-EPERM); |
183 | unsigned long flags; | |
522ed776 | 184 | |
f229c2c1 PH |
185 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
186 | if (current->signal->audit_tty) { | |
187 | buf = current->signal->tty_audit_buf; | |
3c80fe4a TG |
188 | if (buf) |
189 | atomic_inc(&buf->count); | |
190 | } | |
f229c2c1 | 191 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
3c80fe4a TG |
192 | |
193 | /* | |
194 | * Return 0 when signal->audit_tty set | |
f229c2c1 | 195 | * but current->signal->tty_audit_buf == NULL. |
3c80fe4a TG |
196 | */ |
197 | if (!buf || IS_ERR(buf)) | |
198 | return PTR_ERR(buf); | |
522ed776 MT |
199 | |
200 | mutex_lock(&buf->mutex); | |
152f497b | 201 | tty_audit_buf_push(buf); |
522ed776 MT |
202 | mutex_unlock(&buf->mutex); |
203 | ||
204 | tty_audit_buf_put(buf); | |
3c80fe4a | 205 | return 0; |
522ed776 MT |
206 | } |
207 | ||
208 | /** | |
209 | * tty_audit_buf_get - Get an audit buffer. | |
210 | * | |
a75c9b09 | 211 | * Get an audit buffer, allocate it if necessary. Return %NULL |
522ed776 MT |
212 | * if TTY auditing is disabled or out of memory. Otherwise, return a new |
213 | * reference to the buffer. | |
214 | */ | |
a75c9b09 | 215 | static struct tty_audit_buf *tty_audit_buf_get(void) |
522ed776 MT |
216 | { |
217 | struct tty_audit_buf *buf, *buf2; | |
bde02ca8 | 218 | unsigned long flags; |
522ed776 MT |
219 | |
220 | buf = NULL; | |
221 | buf2 = NULL; | |
bde02ca8 | 222 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 MT |
223 | if (likely(!current->signal->audit_tty)) |
224 | goto out; | |
225 | buf = current->signal->tty_audit_buf; | |
226 | if (buf) { | |
227 | atomic_inc(&buf->count); | |
228 | goto out; | |
229 | } | |
bde02ca8 | 230 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 | 231 | |
a75c9b09 | 232 | buf2 = tty_audit_buf_alloc(); |
522ed776 MT |
233 | if (buf2 == NULL) { |
234 | audit_log_lost("out of memory in TTY auditing"); | |
235 | return NULL; | |
236 | } | |
237 | ||
bde02ca8 | 238 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 MT |
239 | if (!current->signal->audit_tty) |
240 | goto out; | |
241 | buf = current->signal->tty_audit_buf; | |
242 | if (!buf) { | |
243 | current->signal->tty_audit_buf = buf2; | |
244 | buf = buf2; | |
245 | buf2 = NULL; | |
246 | } | |
247 | atomic_inc(&buf->count); | |
248 | /* Fall through */ | |
249 | out: | |
bde02ca8 | 250 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
251 | if (buf2) |
252 | tty_audit_buf_free(buf2); | |
253 | return buf; | |
254 | } | |
255 | ||
256 | /** | |
257 | * tty_audit_add_data - Add data for TTY auditing. | |
258 | * | |
259 | * Audit @data of @size from @tty, if necessary. | |
260 | */ | |
309426ae | 261 | void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size) |
522ed776 MT |
262 | { |
263 | struct tty_audit_buf *buf; | |
264 | int major, minor; | |
46e959ea RGB |
265 | int audit_log_tty_passwd; |
266 | unsigned long flags; | |
309426ae | 267 | unsigned int icanon = !!L_ICANON(tty); |
522ed776 MT |
268 | |
269 | if (unlikely(size == 0)) | |
270 | return; | |
271 | ||
d7c0ba40 PH |
272 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
273 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
274 | return; | |
275 | ||
46e959ea RGB |
276 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
277 | audit_log_tty_passwd = current->signal->audit_tty_log_passwd; | |
278 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); | |
279 | if (!audit_log_tty_passwd && icanon && !L_ECHO(tty)) | |
280 | return; | |
281 | ||
a75c9b09 | 282 | buf = tty_audit_buf_get(); |
522ed776 MT |
283 | if (!buf) |
284 | return; | |
285 | ||
286 | mutex_lock(&buf->mutex); | |
287 | major = tty->driver->major; | |
288 | minor = tty->driver->minor_start + tty->index; | |
289 | if (buf->major != major || buf->minor != minor | |
6c633f27 | 290 | || buf->icanon != icanon) { |
152f497b | 291 | tty_audit_buf_push(buf); |
522ed776 MT |
292 | buf->major = major; |
293 | buf->minor = minor; | |
6c633f27 | 294 | buf->icanon = icanon; |
522ed776 MT |
295 | } |
296 | do { | |
297 | size_t run; | |
298 | ||
299 | run = N_TTY_BUF_SIZE - buf->valid; | |
300 | if (run > size) | |
301 | run = size; | |
302 | memcpy(buf->data + buf->valid, data, run); | |
303 | buf->valid += run; | |
304 | data += run; | |
305 | size -= run; | |
306 | if (buf->valid == N_TTY_BUF_SIZE) | |
152f497b | 307 | tty_audit_buf_push(buf); |
522ed776 MT |
308 | } while (size != 0); |
309 | mutex_unlock(&buf->mutex); | |
310 | tty_audit_buf_put(buf); | |
311 | } | |
312 | ||
313 | /** | |
314 | * tty_audit_push - Push buffered data out | |
315 | * | |
b50819f4 | 316 | * Make sure no audit data is pending on the current process. |
522ed776 | 317 | */ |
b50819f4 | 318 | void tty_audit_push(void) |
522ed776 MT |
319 | { |
320 | struct tty_audit_buf *buf; | |
bde02ca8 | 321 | unsigned long flags; |
522ed776 | 322 | |
bde02ca8 | 323 | spin_lock_irqsave(¤t->sighand->siglock, flags); |
522ed776 | 324 | if (likely(!current->signal->audit_tty)) { |
bde02ca8 | 325 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
326 | return; |
327 | } | |
328 | buf = current->signal->tty_audit_buf; | |
329 | if (buf) | |
330 | atomic_inc(&buf->count); | |
bde02ca8 | 331 | spin_unlock_irqrestore(¤t->sighand->siglock, flags); |
522ed776 MT |
332 | |
333 | if (buf) { | |
522ed776 | 334 | mutex_lock(&buf->mutex); |
b50819f4 | 335 | tty_audit_buf_push(buf); |
522ed776 MT |
336 | mutex_unlock(&buf->mutex); |
337 | tty_audit_buf_put(buf); | |
338 | } | |
339 | } |