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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> | |
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 | ||
70 | /** | |
71 | * tty_audit_buf_push - Push buffered data out | |
72 | * | |
73 | * Generate an audit message from the contents of @buf, which is owned by | |
74 | * @tsk with @loginuid. @buf->mutex must be locked. | |
75 | */ | |
76 | static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid, | |
4746ec5b | 77 | unsigned int sessionid, |
522ed776 MT |
78 | struct tty_audit_buf *buf) |
79 | { | |
80 | struct audit_buffer *ab; | |
81 | ||
82 | if (buf->valid == 0) | |
83 | return; | |
84 | if (audit_enabled == 0) | |
85 | return; | |
86 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); | |
87 | if (ab) { | |
88 | char name[sizeof(tsk->comm)]; | |
66303bce | 89 | uid_t uid = task_uid(tsk); |
522ed776 | 90 | |
4746ec5b | 91 | audit_log_format(ab, "tty pid=%u uid=%u auid=%u ses=%u " |
66303bce DH |
92 | "major=%d minor=%d comm=", |
93 | tsk->pid, uid, loginuid, sessionid, | |
94 | buf->major, buf->minor); | |
522ed776 MT |
95 | get_task_comm(name, tsk); |
96 | audit_log_untrustedstring(ab, name); | |
97 | audit_log_format(ab, " data="); | |
7459b6ff | 98 | audit_log_n_hex(ab, buf->data, buf->valid); |
522ed776 MT |
99 | audit_log_end(ab); |
100 | } | |
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 | ||
154 | /** | |
155 | * tty_audit_push_task - Flush task's pending audit data | |
156 | */ | |
2532386f | 157 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
522ed776 MT |
158 | { |
159 | struct tty_audit_buf *buf; | |
160 | ||
161 | spin_lock_irq(&tsk->sighand->siglock); | |
162 | buf = tsk->signal->tty_audit_buf; | |
163 | if (buf) | |
164 | atomic_inc(&buf->count); | |
165 | spin_unlock_irq(&tsk->sighand->siglock); | |
166 | if (!buf) | |
167 | return; | |
168 | ||
169 | mutex_lock(&buf->mutex); | |
4746ec5b | 170 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
522ed776 MT |
171 | mutex_unlock(&buf->mutex); |
172 | ||
173 | tty_audit_buf_put(buf); | |
174 | } | |
175 | ||
176 | /** | |
177 | * tty_audit_buf_get - Get an audit buffer. | |
178 | * | |
179 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL | |
180 | * if TTY auditing is disabled or out of memory. Otherwise, return a new | |
181 | * reference to the buffer. | |
182 | */ | |
183 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) | |
184 | { | |
185 | struct tty_audit_buf *buf, *buf2; | |
186 | ||
187 | buf = NULL; | |
188 | buf2 = NULL; | |
189 | spin_lock_irq(¤t->sighand->siglock); | |
190 | if (likely(!current->signal->audit_tty)) | |
191 | goto out; | |
192 | buf = current->signal->tty_audit_buf; | |
193 | if (buf) { | |
194 | atomic_inc(&buf->count); | |
195 | goto out; | |
196 | } | |
197 | spin_unlock_irq(¤t->sighand->siglock); | |
198 | ||
199 | buf2 = tty_audit_buf_alloc(tty->driver->major, | |
200 | tty->driver->minor_start + tty->index, | |
201 | tty->icanon); | |
202 | if (buf2 == NULL) { | |
203 | audit_log_lost("out of memory in TTY auditing"); | |
204 | return NULL; | |
205 | } | |
206 | ||
207 | spin_lock_irq(¤t->sighand->siglock); | |
208 | if (!current->signal->audit_tty) | |
209 | goto out; | |
210 | buf = current->signal->tty_audit_buf; | |
211 | if (!buf) { | |
212 | current->signal->tty_audit_buf = buf2; | |
213 | buf = buf2; | |
214 | buf2 = NULL; | |
215 | } | |
216 | atomic_inc(&buf->count); | |
217 | /* Fall through */ | |
218 | out: | |
219 | spin_unlock_irq(¤t->sighand->siglock); | |
220 | if (buf2) | |
221 | tty_audit_buf_free(buf2); | |
222 | return buf; | |
223 | } | |
224 | ||
225 | /** | |
226 | * tty_audit_add_data - Add data for TTY auditing. | |
227 | * | |
228 | * Audit @data of @size from @tty, if necessary. | |
229 | */ | |
230 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, | |
231 | size_t size) | |
232 | { | |
233 | struct tty_audit_buf *buf; | |
234 | int major, minor; | |
235 | ||
236 | if (unlikely(size == 0)) | |
237 | return; | |
238 | ||
41126226 MT |
239 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
240 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
241 | return; | |
242 | ||
522ed776 MT |
243 | buf = tty_audit_buf_get(tty); |
244 | if (!buf) | |
245 | return; | |
246 | ||
247 | mutex_lock(&buf->mutex); | |
248 | major = tty->driver->major; | |
249 | minor = tty->driver->minor_start + tty->index; | |
250 | if (buf->major != major || buf->minor != minor | |
251 | || buf->icanon != tty->icanon) { | |
252 | tty_audit_buf_push_current(buf); | |
253 | buf->major = major; | |
254 | buf->minor = minor; | |
255 | buf->icanon = tty->icanon; | |
256 | } | |
257 | do { | |
258 | size_t run; | |
259 | ||
260 | run = N_TTY_BUF_SIZE - buf->valid; | |
261 | if (run > size) | |
262 | run = size; | |
263 | memcpy(buf->data + buf->valid, data, run); | |
264 | buf->valid += run; | |
265 | data += run; | |
266 | size -= run; | |
267 | if (buf->valid == N_TTY_BUF_SIZE) | |
268 | tty_audit_buf_push_current(buf); | |
269 | } while (size != 0); | |
270 | mutex_unlock(&buf->mutex); | |
271 | tty_audit_buf_put(buf); | |
272 | } | |
273 | ||
274 | /** | |
275 | * tty_audit_push - Push buffered data out | |
276 | * | |
277 | * Make sure no audit data is pending for @tty on the current process. | |
278 | */ | |
279 | void tty_audit_push(struct tty_struct *tty) | |
280 | { | |
281 | struct tty_audit_buf *buf; | |
282 | ||
283 | spin_lock_irq(¤t->sighand->siglock); | |
284 | if (likely(!current->signal->audit_tty)) { | |
285 | spin_unlock_irq(¤t->sighand->siglock); | |
286 | return; | |
287 | } | |
288 | buf = current->signal->tty_audit_buf; | |
289 | if (buf) | |
290 | atomic_inc(&buf->count); | |
291 | spin_unlock_irq(¤t->sighand->siglock); | |
292 | ||
293 | if (buf) { | |
294 | int major, minor; | |
295 | ||
296 | major = tty->driver->major; | |
297 | minor = tty->driver->minor_start + tty->index; | |
298 | mutex_lock(&buf->mutex); | |
299 | if (buf->major == major && buf->minor == minor) | |
300 | tty_audit_buf_push_current(buf); | |
301 | mutex_unlock(&buf->mutex); | |
302 | tty_audit_buf_put(buf); | |
303 | } | |
304 | } |