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-rw-r--r--drivers/tty/tty_audit.c358
1 files changed, 358 insertions, 0 deletions
diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
new file mode 100644
index 000000000000..f64582b0f623
--- /dev/null
+++ b/drivers/tty/tty_audit.c
@@ -0,0 +1,358 @@
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/slab.h>
14#include <linux/tty.h>
15
16struct 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
25static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
26 int icanon)
27{
28 struct tty_audit_buf *buf;
29
30 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
31 if (!buf)
32 goto err;
33 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
34 if (!buf->data)
35 goto err_buf;
36 atomic_set(&buf->count, 1);
37 mutex_init(&buf->mutex);
38 buf->major = major;
39 buf->minor = minor;
40 buf->icanon = icanon;
41 buf->valid = 0;
42 return buf;
43
44err_buf:
45 kfree(buf);
46err:
47 return NULL;
48}
49
50static void tty_audit_buf_free(struct tty_audit_buf *buf)
51{
52 WARN_ON(buf->valid != 0);
53 kfree(buf->data);
54 kfree(buf);
55}
56
57static void tty_audit_buf_put(struct tty_audit_buf *buf)
58{
59 if (atomic_dec_and_test(&buf->count))
60 tty_audit_buf_free(buf);
61}
62
63static void tty_audit_log(const char *description, struct task_struct *tsk,
64 uid_t loginuid, unsigned sessionid, int major,
65 int minor, unsigned char *data, size_t size)
66{
67 struct audit_buffer *ab;
68
69 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
70 if (ab) {
71 char name[sizeof(tsk->comm)];
72 uid_t uid = task_uid(tsk);
73
74 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
75 "major=%d minor=%d comm=", description,
76 tsk->pid, uid, loginuid, sessionid,
77 major, minor);
78 get_task_comm(name, tsk);
79 audit_log_untrustedstring(ab, name);
80 audit_log_format(ab, " data=");
81 audit_log_n_hex(ab, data, size);
82 audit_log_end(ab);
83 }
84}
85
86/**
87 * tty_audit_buf_push - Push buffered data out
88 *
89 * Generate an audit message from the contents of @buf, which is owned by
90 * @tsk with @loginuid. @buf->mutex must be locked.
91 */
92static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
93 unsigned int sessionid,
94 struct tty_audit_buf *buf)
95{
96 if (buf->valid == 0)
97 return;
98 if (audit_enabled == 0)
99 return;
100 tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
101 buf->data, buf->valid);
102 buf->valid = 0;
103}
104
105/**
106 * tty_audit_buf_push_current - Push buffered data out
107 *
108 * Generate an audit message from the contents of @buf, which is owned by
109 * the current task. @buf->mutex must be locked.
110 */
111static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
112{
113 uid_t auid = audit_get_loginuid(current);
114 unsigned int sessionid = audit_get_sessionid(current);
115 tty_audit_buf_push(current, auid, sessionid, buf);
116}
117
118/**
119 * tty_audit_exit - Handle a task exit
120 *
121 * Make sure all buffered data is written out and deallocate the buffer.
122 * Only needs to be called if current->signal->tty_audit_buf != %NULL.
123 */
124void tty_audit_exit(void)
125{
126 struct tty_audit_buf *buf;
127
128 spin_lock_irq(&current->sighand->siglock);
129 buf = current->signal->tty_audit_buf;
130 current->signal->tty_audit_buf = NULL;
131 spin_unlock_irq(&current->sighand->siglock);
132 if (!buf)
133 return;
134
135 mutex_lock(&buf->mutex);
136 tty_audit_buf_push_current(buf);
137 mutex_unlock(&buf->mutex);
138
139 tty_audit_buf_put(buf);
140}
141
142/**
143 * tty_audit_fork - Copy TTY audit state for a new task
144 *
145 * Set up TTY audit state in @sig from current. @sig needs no locking.
146 */
147void tty_audit_fork(struct signal_struct *sig)
148{
149 spin_lock_irq(&current->sighand->siglock);
150 sig->audit_tty = current->signal->audit_tty;
151 spin_unlock_irq(&current->sighand->siglock);
152}
153
154/**
155 * tty_audit_tiocsti - Log TIOCSTI
156 */
157void 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(&current->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(&current->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
190/**
191 * tty_audit_push_task - Flush task's pending audit data
192 * @tsk: task pointer
193 * @loginuid: sender login uid
194 * @sessionid: sender session id
195 *
196 * Called with a ref on @tsk held. Try to lock sighand and get a
197 * reference to the tty audit buffer if available.
198 * Flush the buffer or return an appropriate error code.
199 */
200int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
201{
202 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
203 unsigned long flags;
204
205 if (!lock_task_sighand(tsk, &flags))
206 return -ESRCH;
207
208 if (tsk->signal->audit_tty) {
209 buf = tsk->signal->tty_audit_buf;
210 if (buf)
211 atomic_inc(&buf->count);
212 }
213 unlock_task_sighand(tsk, &flags);
214
215 /*
216 * Return 0 when signal->audit_tty set
217 * but tsk->signal->tty_audit_buf == NULL.
218 */
219 if (!buf || IS_ERR(buf))
220 return PTR_ERR(buf);
221
222 mutex_lock(&buf->mutex);
223 tty_audit_buf_push(tsk, loginuid, sessionid, buf);
224 mutex_unlock(&buf->mutex);
225
226 tty_audit_buf_put(buf);
227 return 0;
228}
229
230/**
231 * tty_audit_buf_get - Get an audit buffer.
232 *
233 * Get an audit buffer for @tty, allocate it if necessary. Return %NULL
234 * if TTY auditing is disabled or out of memory. Otherwise, return a new
235 * reference to the buffer.
236 */
237static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
238{
239 struct tty_audit_buf *buf, *buf2;
240
241 buf = NULL;
242 buf2 = NULL;
243 spin_lock_irq(&current->sighand->siglock);
244 if (likely(!current->signal->audit_tty))
245 goto out;
246 buf = current->signal->tty_audit_buf;
247 if (buf) {
248 atomic_inc(&buf->count);
249 goto out;
250 }
251 spin_unlock_irq(&current->sighand->siglock);
252
253 buf2 = tty_audit_buf_alloc(tty->driver->major,
254 tty->driver->minor_start + tty->index,
255 tty->icanon);
256 if (buf2 == NULL) {
257 audit_log_lost("out of memory in TTY auditing");
258 return NULL;
259 }
260
261 spin_lock_irq(&current->sighand->siglock);
262 if (!current->signal->audit_tty)
263 goto out;
264 buf = current->signal->tty_audit_buf;
265 if (!buf) {
266 current->signal->tty_audit_buf = buf2;
267 buf = buf2;
268 buf2 = NULL;
269 }
270 atomic_inc(&buf->count);
271 /* Fall through */
272 out:
273 spin_unlock_irq(&current->sighand->siglock);
274 if (buf2)
275 tty_audit_buf_free(buf2);
276 return buf;
277}
278
279/**
280 * tty_audit_add_data - Add data for TTY auditing.
281 *
282 * Audit @data of @size from @tty, if necessary.
283 */
284void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
285 size_t size)
286{
287 struct tty_audit_buf *buf;
288 int major, minor;
289
290 if (unlikely(size == 0))
291 return;
292
293 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
294 && tty->driver->subtype == PTY_TYPE_MASTER)
295 return;
296
297 buf = tty_audit_buf_get(tty);
298 if (!buf)
299 return;
300
301 mutex_lock(&buf->mutex);
302 major = tty->driver->major;
303 minor = tty->driver->minor_start + tty->index;
304 if (buf->major != major || buf->minor != minor
305 || buf->icanon != tty->icanon) {
306 tty_audit_buf_push_current(buf);
307 buf->major = major;
308 buf->minor = minor;
309 buf->icanon = tty->icanon;
310 }
311 do {
312 size_t run;
313
314 run = N_TTY_BUF_SIZE - buf->valid;
315 if (run > size)
316 run = size;
317 memcpy(buf->data + buf->valid, data, run);
318 buf->valid += run;
319 data += run;
320 size -= run;
321 if (buf->valid == N_TTY_BUF_SIZE)
322 tty_audit_buf_push_current(buf);
323 } while (size != 0);
324 mutex_unlock(&buf->mutex);
325 tty_audit_buf_put(buf);
326}
327
328/**
329 * tty_audit_push - Push buffered data out
330 *
331 * Make sure no audit data is pending for @tty on the current process.
332 */
333void tty_audit_push(struct tty_struct *tty)
334{
335 struct tty_audit_buf *buf;
336
337 spin_lock_irq(&current->sighand->siglock);
338 if (likely(!current->signal->audit_tty)) {
339 spin_unlock_irq(&current->sighand->siglock);
340 return;
341 }
342 buf = current->signal->tty_audit_buf;
343 if (buf)
344 atomic_inc(&buf->count);
345 spin_unlock_irq(&current->sighand->siglock);
346
347 if (buf) {
348 int major, minor;
349
350 major = tty->driver->major;
351 minor = tty->driver->minor_start + tty->index;
352 mutex_lock(&buf->mutex);
353 if (buf->major == major && buf->minor == minor)
354 tty_audit_buf_push_current(buf);
355 mutex_unlock(&buf->mutex);
356 tty_audit_buf_put(buf);
357 }
358}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-05 08:39:23 -0500