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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 buf->valid = 0;
100 return;
101 }
102 tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
103 buf->data, buf->valid);
104 buf->valid = 0;
105}
106
107/**
108 * tty_audit_buf_push_current - Push buffered data out
109 *
110 * Generate an audit message from the contents of @buf, which is owned by
111 * the current task. @buf->mutex must be locked.
112 */
113static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
114{
115 uid_t auid = audit_get_loginuid(current);
116 unsigned int sessionid = audit_get_sessionid(current);
117 tty_audit_buf_push(current, auid, sessionid, buf);
118}
119
120/**
121 * tty_audit_exit - Handle a task exit
122 *
123 * Make sure all buffered data is written out and deallocate the buffer.
124 * Only needs to be called if current->signal->tty_audit_buf != %NULL.
125 */
126void tty_audit_exit(void)
127{
128 struct tty_audit_buf *buf;
129
130 spin_lock_irq(¤t->sighand->siglock);
131 buf = current->signal->tty_audit_buf;
132 current->signal->tty_audit_buf = NULL;
133 spin_unlock_irq(¤t->sighand->siglock);
134 if (!buf)
135 return;
136
137 mutex_lock(&buf->mutex);
138 tty_audit_buf_push_current(buf);
139 mutex_unlock(&buf->mutex);
140
141 tty_audit_buf_put(buf);
142}
143
144/**
145 * tty_audit_fork - Copy TTY audit state for a new task
146 *
147 * Set up TTY audit state in @sig from current. @sig needs no locking.
148 */
149void tty_audit_fork(struct signal_struct *sig)
150{
151 spin_lock_irq(¤t->sighand->siglock);
152 sig->audit_tty = current->signal->audit_tty;
153 spin_unlock_irq(¤t->sighand->siglock);
154}
155
156/**
157 * tty_audit_tiocsti - Log TIOCSTI
158 */
159void tty_audit_tiocsti(struct tty_struct *tty, char ch)
160{
161 struct tty_audit_buf *buf;
162 int major, minor, should_audit;
163
164 spin_lock_irq(¤t->sighand->siglock);
165 should_audit = current->signal->audit_tty;
166 buf = current->signal->tty_audit_buf;
167 if (buf)
168 atomic_inc(&buf->count);
169 spin_unlock_irq(¤t->sighand->siglock);
170
171 major = tty->driver->major;
172 minor = tty->driver->minor_start + tty->index;
173 if (buf) {
174 mutex_lock(&buf->mutex);
175 if (buf->major == major && buf->minor == minor)
176 tty_audit_buf_push_current(buf);
177 mutex_unlock(&buf->mutex);
178 tty_audit_buf_put(buf);
179 }
180
181 if (should_audit && audit_enabled) {
182 uid_t auid;
183 unsigned int sessionid;
184
185 auid = audit_get_loginuid(current);
186 sessionid = audit_get_sessionid(current);
187 tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
188 minor, &ch, 1);
189 }
190}
191
192/**
193 * tty_audit_push_task - Flush task's pending audit data
194 * @tsk: task pointer
195 * @loginuid: sender login uid
196 * @sessionid: sender session id
197 *
198 * Called with a ref on @tsk held. Try to lock sighand and get a
199 * reference to the tty audit buffer if available.
200 * Flush the buffer or return an appropriate error code.
201 */
202int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
203{
204 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
205 unsigned long flags;
206
207 if (!lock_task_sighand(tsk, &flags))
208 return -ESRCH;
209
210 if (tsk->signal->audit_tty) {
211 buf = tsk->signal->tty_audit_buf;
212 if (buf)
213 atomic_inc(&buf->count);
214 }
215 unlock_task_sighand(tsk, &flags);
216
217 /*
218 * Return 0 when signal->audit_tty set
219 * but tsk->signal->tty_audit_buf == NULL.
220 */
221 if (!buf || IS_ERR(buf))
222 return PTR_ERR(buf);
223
224 mutex_lock(&buf->mutex);
225 tty_audit_buf_push(tsk, loginuid, sessionid, buf);
226 mutex_unlock(&buf->mutex);
227
228 tty_audit_buf_put(buf);
229 return 0;
230}
231
232/**
233 * tty_audit_buf_get - Get an audit buffer.
234 *
235 * Get an audit buffer for @tty, allocate it if necessary. Return %NULL
236 * if TTY auditing is disabled or out of memory. Otherwise, return a new
237 * reference to the buffer.
238 */
239static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
240{
241 struct tty_audit_buf *buf, *buf2;
242
243 buf = NULL;
244 buf2 = NULL;
245 spin_lock_irq(¤t->sighand->siglock);
246 if (likely(!current->signal->audit_tty))
247 goto out;
248 buf = current->signal->tty_audit_buf;
249 if (buf) {
250 atomic_inc(&buf->count);
251 goto out;
252 }
253 spin_unlock_irq(¤t->sighand->siglock);
254
255 buf2 = tty_audit_buf_alloc(tty->driver->major,
256 tty->driver->minor_start + tty->index,
257 tty->icanon);
258 if (buf2 == NULL) {
259 audit_log_lost("out of memory in TTY auditing");
260 return NULL;
261 }
262
263 spin_lock_irq(¤t->sighand->siglock);
264 if (!current->signal->audit_tty)
265 goto out;
266 buf = current->signal->tty_audit_buf;
267 if (!buf) {
268 current->signal->tty_audit_buf = buf2;
269 buf = buf2;
270 buf2 = NULL;
271 }
272 atomic_inc(&buf->count);
273 /* Fall through */
274 out:
275 spin_unlock_irq(¤t->sighand->siglock);
276 if (buf2)
277 tty_audit_buf_free(buf2);
278 return buf;
279}
280
281/**
282 * tty_audit_add_data - Add data for TTY auditing.
283 *
284 * Audit @data of @size from @tty, if necessary.
285 */
286void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
287 size_t size)
288{
289 struct tty_audit_buf *buf;
290 int major, minor;
291
292 if (unlikely(size == 0))
293 return;
294
295 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
296 && tty->driver->subtype == PTY_TYPE_MASTER)
297 return;
298
299 buf = tty_audit_buf_get(tty);
300 if (!buf)
301 return;
302
303 mutex_lock(&buf->mutex);
304 major = tty->driver->major;
305 minor = tty->driver->minor_start + tty->index;
306 if (buf->major != major || buf->minor != minor
307 || buf->icanon != tty->icanon) {
308 tty_audit_buf_push_current(buf);
309 buf->major = major;
310 buf->minor = minor;
311 buf->icanon = tty->icanon;
312 }
313 do {
314 size_t run;
315
316 run = N_TTY_BUF_SIZE - buf->valid;
317 if (run > size)
318 run = size;
319 memcpy(buf->data + buf->valid, data, run);
320 buf->valid += run;
321 data += run;
322 size -= run;
323 if (buf->valid == N_TTY_BUF_SIZE)
324 tty_audit_buf_push_current(buf);
325 } while (size != 0);
326 mutex_unlock(&buf->mutex);
327 tty_audit_buf_put(buf);
328}
329
330/**
331 * tty_audit_push - Push buffered data out
332 *
333 * Make sure no audit data is pending for @tty on the current process.
334 */
335void tty_audit_push(struct tty_struct *tty)
336{
337 struct tty_audit_buf *buf;
338
339 spin_lock_irq(¤t->sighand->siglock);
340 if (likely(!current->signal->audit_tty)) {
341 spin_unlock_irq(¤t->sighand->siglock);
342 return;
343 }
344 buf = current->signal->tty_audit_buf;
345 if (buf)
346 atomic_inc(&buf->count);
347 spin_unlock_irq(¤t->sighand->siglock);
348
349 if (buf) {
350 int major, minor;
351
352 major = tty->driver->major;
353 minor = tty->driver->minor_start + tty->index;
354 mutex_lock(&buf->mutex);
355 if (buf->major == major && buf->minor == minor)
356 tty_audit_buf_push_current(buf);
357 mutex_unlock(&buf->mutex);
358 tty_audit_buf_put(buf);
359 }
360}
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 struct mutex mutex; /* Protects all data below */
18 dev_t dev; /* 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
24static struct tty_audit_buf *tty_audit_buf_ref(void)
25{
26 struct tty_audit_buf *buf;
27
28 buf = current->signal->tty_audit_buf;
29 WARN_ON(buf == ERR_PTR(-ESRCH));
30 return buf;
31}
32
33static struct tty_audit_buf *tty_audit_buf_alloc(void)
34{
35 struct tty_audit_buf *buf;
36
37 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
38 if (!buf)
39 goto err;
40 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
41 if (!buf->data)
42 goto err_buf;
43 mutex_init(&buf->mutex);
44 buf->dev = MKDEV(0, 0);
45 buf->icanon = 0;
46 buf->valid = 0;
47 return buf;
48
49err_buf:
50 kfree(buf);
51err:
52 return NULL;
53}
54
55static void tty_audit_buf_free(struct tty_audit_buf *buf)
56{
57 WARN_ON(buf->valid != 0);
58 kfree(buf->data);
59 kfree(buf);
60}
61
62static void tty_audit_log(const char *description, dev_t dev,
63 unsigned char *data, size_t size)
64{
65 struct audit_buffer *ab;
66 struct task_struct *tsk = current;
67 pid_t pid = task_pid_nr(tsk);
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));
70 unsigned int sessionid = audit_get_sessionid(tsk);
71
72 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
73 if (ab) {
74 char name[sizeof(tsk->comm)];
75
76 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
77 " minor=%d comm=", description, pid, uid,
78 loginuid, sessionid, MAJOR(dev), MINOR(dev));
79 get_task_comm(name, tsk);
80 audit_log_untrustedstring(ab, name);
81 audit_log_format(ab, " data=");
82 audit_log_n_hex(ab, data, size);
83 audit_log_end(ab);
84 }
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
91 * the current task. @buf->mutex must be locked.
92 */
93static void tty_audit_buf_push(struct tty_audit_buf *buf)
94{
95 if (buf->valid == 0)
96 return;
97 if (audit_enabled == 0) {
98 buf->valid = 0;
99 return;
100 }
101 tty_audit_log("tty", buf->dev, buf->data, buf->valid);
102 buf->valid = 0;
103}
104
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 * The process is single-threaded at this point; no other threads share
112 * current->signal.
113 */
114void tty_audit_exit(void)
115{
116 struct tty_audit_buf *buf;
117
118 buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH));
119 if (!buf)
120 return;
121
122 tty_audit_buf_push(buf);
123 tty_audit_buf_free(buf);
124}
125
126/**
127 * tty_audit_fork - Copy TTY audit state for a new task
128 *
129 * Set up TTY audit state in @sig from current. @sig needs no locking.
130 */
131void tty_audit_fork(struct signal_struct *sig)
132{
133 sig->audit_tty = current->signal->audit_tty;
134}
135
136/**
137 * tty_audit_tiocsti - Log TIOCSTI
138 */
139void tty_audit_tiocsti(struct tty_struct *tty, char ch)
140{
141 dev_t dev;
142
143 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
144 if (tty_audit_push())
145 return;
146
147 if (audit_enabled)
148 tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1);
149}
150
151/**
152 * tty_audit_push - Flush current's pending audit data
153 *
154 * Returns 0 if success, -EPERM if tty audit is disabled
155 */
156int tty_audit_push(void)
157{
158 struct tty_audit_buf *buf;
159
160 if (~current->signal->audit_tty & AUDIT_TTY_ENABLE)
161 return -EPERM;
162
163 buf = tty_audit_buf_ref();
164 if (!IS_ERR_OR_NULL(buf)) {
165 mutex_lock(&buf->mutex);
166 tty_audit_buf_push(buf);
167 mutex_unlock(&buf->mutex);
168 }
169 return 0;
170}
171
172/**
173 * tty_audit_buf_get - Get an audit buffer.
174 *
175 * Get an audit buffer, allocate it if necessary. Return %NULL
176 * if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already
177 * occurred. Otherwise, return a new reference to the buffer.
178 */
179static struct tty_audit_buf *tty_audit_buf_get(void)
180{
181 struct tty_audit_buf *buf;
182
183 buf = tty_audit_buf_ref();
184 if (buf)
185 return buf;
186
187 buf = tty_audit_buf_alloc();
188 if (buf == NULL) {
189 audit_log_lost("out of memory in TTY auditing");
190 return NULL;
191 }
192
193 /* Race to use this buffer, free it if another wins */
194 if (cmpxchg(¤t->signal->tty_audit_buf, NULL, buf) != NULL)
195 tty_audit_buf_free(buf);
196 return tty_audit_buf_ref();
197}
198
199/**
200 * tty_audit_add_data - Add data for TTY auditing.
201 *
202 * Audit @data of @size from @tty, if necessary.
203 */
204void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size)
205{
206 struct tty_audit_buf *buf;
207 unsigned int icanon = !!L_ICANON(tty);
208 unsigned int audit_tty;
209 dev_t dev;
210
211 audit_tty = READ_ONCE(current->signal->audit_tty);
212 if (~audit_tty & AUDIT_TTY_ENABLE)
213 return;
214
215 if (unlikely(size == 0))
216 return;
217
218 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
219 && tty->driver->subtype == PTY_TYPE_MASTER)
220 return;
221
222 if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty))
223 return;
224
225 buf = tty_audit_buf_get();
226 if (IS_ERR_OR_NULL(buf))
227 return;
228
229 mutex_lock(&buf->mutex);
230 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
231 if (buf->dev != dev || buf->icanon != icanon) {
232 tty_audit_buf_push(buf);
233 buf->dev = dev;
234 buf->icanon = icanon;
235 }
236 do {
237 size_t run;
238
239 run = N_TTY_BUF_SIZE - buf->valid;
240 if (run > size)
241 run = size;
242 memcpy(buf->data + buf->valid, data, run);
243 buf->valid += run;
244 data += run;
245 size -= run;
246 if (buf->valid == N_TTY_BUF_SIZE)
247 tty_audit_buf_push(buf);
248 } while (size != 0);
249 mutex_unlock(&buf->mutex);
250}