Merge branch 'fix/asoc' into for-linus
[linux-2.6] / drivers / char / tty_audit.c
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/tty.h>
14
15 struct tty_audit_buf {
16         atomic_t count;
17         struct mutex mutex;     /* Protects all data below */
18         int major, minor;       /* 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
24 static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
25                                                  int icanon)
26 {
27         struct tty_audit_buf *buf;
28
29         buf = kmalloc(sizeof(*buf), GFP_KERNEL);
30         if (!buf)
31                 goto err;
32         if (PAGE_SIZE != N_TTY_BUF_SIZE)
33                 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
34         else
35                 buf->data = (unsigned char *)__get_free_page(GFP_KERNEL);
36         if (!buf->data)
37                 goto err_buf;
38         atomic_set(&buf->count, 1);
39         mutex_init(&buf->mutex);
40         buf->major = major;
41         buf->minor = minor;
42         buf->icanon = icanon;
43         buf->valid = 0;
44         return buf;
45
46 err_buf:
47         kfree(buf);
48 err:
49         return NULL;
50 }
51
52 static void tty_audit_buf_free(struct tty_audit_buf *buf)
53 {
54         WARN_ON(buf->valid != 0);
55         if (PAGE_SIZE != N_TTY_BUF_SIZE)
56                 kfree(buf->data);
57         else
58                 free_page((unsigned long)buf->data);
59         kfree(buf);
60 }
61
62 static void tty_audit_buf_put(struct tty_audit_buf *buf)
63 {
64         if (atomic_dec_and_test(&buf->count))
65                 tty_audit_buf_free(buf);
66 }
67
68 static void tty_audit_log(const char *description, struct task_struct *tsk,
69                           uid_t loginuid, unsigned sessionid, int major,
70                           int minor, unsigned char *data, size_t size)
71 {
72         struct audit_buffer *ab;
73
74         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
75         if (ab) {
76                 char name[sizeof(tsk->comm)];
77                 uid_t uid = task_uid(tsk);
78
79                 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
80                                  "major=%d minor=%d comm=", description,
81                                  tsk->pid, uid, loginuid, sessionid,
82                                  major, minor);
83                 get_task_comm(name, tsk);
84                 audit_log_untrustedstring(ab, name);
85                 audit_log_format(ab, " data=");
86                 audit_log_n_hex(ab, data, size);
87                 audit_log_end(ab);
88         }
89 }
90
91 /**
92  *      tty_audit_buf_push      -       Push buffered data out
93  *
94  *      Generate an audit message from the contents of @buf, which is owned by
95  *      @tsk with @loginuid.  @buf->mutex must be locked.
96  */
97 static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
98                                unsigned int sessionid,
99                                struct tty_audit_buf *buf)
100 {
101         if (buf->valid == 0)
102                 return;
103         if (audit_enabled == 0)
104                 return;
105         tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
106                       buf->data, buf->valid);
107         buf->valid = 0;
108 }
109
110 /**
111  *      tty_audit_buf_push_current      -       Push buffered data out
112  *
113  *      Generate an audit message from the contents of @buf, which is owned by
114  *      the current task.  @buf->mutex must be locked.
115  */
116 static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
117 {
118         uid_t auid = audit_get_loginuid(current);
119         unsigned int sessionid = audit_get_sessionid(current);
120         tty_audit_buf_push(current, auid, sessionid, buf);
121 }
122
123 /**
124  *      tty_audit_exit  -       Handle a task exit
125  *
126  *      Make sure all buffered data is written out and deallocate the buffer.
127  *      Only needs to be called if current->signal->tty_audit_buf != %NULL.
128  */
129 void tty_audit_exit(void)
130 {
131         struct tty_audit_buf *buf;
132
133         spin_lock_irq(&current->sighand->siglock);
134         buf = current->signal->tty_audit_buf;
135         current->signal->tty_audit_buf = NULL;
136         spin_unlock_irq(&current->sighand->siglock);
137         if (!buf)
138                 return;
139
140         mutex_lock(&buf->mutex);
141         tty_audit_buf_push_current(buf);
142         mutex_unlock(&buf->mutex);
143
144         tty_audit_buf_put(buf);
145 }
146
147 /**
148  *      tty_audit_fork  -       Copy TTY audit state for a new task
149  *
150  *      Set up TTY audit state in @sig from current.  @sig needs no locking.
151  */
152 void tty_audit_fork(struct signal_struct *sig)
153 {
154         spin_lock_irq(&current->sighand->siglock);
155         sig->audit_tty = current->signal->audit_tty;
156         spin_unlock_irq(&current->sighand->siglock);
157         sig->tty_audit_buf = NULL;
158 }
159
160 /**
161  *      tty_audit_tiocsti       -       Log TIOCSTI
162  */
163 void tty_audit_tiocsti(struct tty_struct *tty, char ch)
164 {
165         struct tty_audit_buf *buf;
166         int major, minor, should_audit;
167
168         spin_lock_irq(&current->sighand->siglock);
169         should_audit = current->signal->audit_tty;
170         buf = current->signal->tty_audit_buf;
171         if (buf)
172                 atomic_inc(&buf->count);
173         spin_unlock_irq(&current->sighand->siglock);
174
175         major = tty->driver->major;
176         minor = tty->driver->minor_start + tty->index;
177         if (buf) {
178                 mutex_lock(&buf->mutex);
179                 if (buf->major == major && buf->minor == minor)
180                         tty_audit_buf_push_current(buf);
181                 mutex_unlock(&buf->mutex);
182                 tty_audit_buf_put(buf);
183         }
184
185         if (should_audit && audit_enabled) {
186                 uid_t auid;
187                 unsigned int sessionid;
188
189                 auid = audit_get_loginuid(current);
190                 sessionid = audit_get_sessionid(current);
191                 tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
192                               minor, &ch, 1);
193         }
194 }
195
196 /**
197  *      tty_audit_push_task     -       Flush task's pending audit data
198  */
199 void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
200 {
201         struct tty_audit_buf *buf;
202
203         spin_lock_irq(&tsk->sighand->siglock);
204         buf = tsk->signal->tty_audit_buf;
205         if (buf)
206                 atomic_inc(&buf->count);
207         spin_unlock_irq(&tsk->sighand->siglock);
208         if (!buf)
209                 return;
210
211         mutex_lock(&buf->mutex);
212         tty_audit_buf_push(tsk, loginuid, sessionid, buf);
213         mutex_unlock(&buf->mutex);
214
215         tty_audit_buf_put(buf);
216 }
217
218 /**
219  *      tty_audit_buf_get       -       Get an audit buffer.
220  *
221  *      Get an audit buffer for @tty, allocate it if necessary.  Return %NULL
222  *      if TTY auditing is disabled or out of memory.  Otherwise, return a new
223  *      reference to the buffer.
224  */
225 static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
226 {
227         struct tty_audit_buf *buf, *buf2;
228
229         buf = NULL;
230         buf2 = NULL;
231         spin_lock_irq(&current->sighand->siglock);
232         if (likely(!current->signal->audit_tty))
233                 goto out;
234         buf = current->signal->tty_audit_buf;
235         if (buf) {
236                 atomic_inc(&buf->count);
237                 goto out;
238         }
239         spin_unlock_irq(&current->sighand->siglock);
240
241         buf2 = tty_audit_buf_alloc(tty->driver->major,
242                                    tty->driver->minor_start + tty->index,
243                                    tty->icanon);
244         if (buf2 == NULL) {
245                 audit_log_lost("out of memory in TTY auditing");
246                 return NULL;
247         }
248
249         spin_lock_irq(&current->sighand->siglock);
250         if (!current->signal->audit_tty)
251                 goto out;
252         buf = current->signal->tty_audit_buf;
253         if (!buf) {
254                 current->signal->tty_audit_buf = buf2;
255                 buf = buf2;
256                 buf2 = NULL;
257         }
258         atomic_inc(&buf->count);
259         /* Fall through */
260  out:
261         spin_unlock_irq(&current->sighand->siglock);
262         if (buf2)
263                 tty_audit_buf_free(buf2);
264         return buf;
265 }
266
267 /**
268  *      tty_audit_add_data      -       Add data for TTY auditing.
269  *
270  *      Audit @data of @size from @tty, if necessary.
271  */
272 void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
273                         size_t size)
274 {
275         struct tty_audit_buf *buf;
276         int major, minor;
277
278         if (unlikely(size == 0))
279                 return;
280
281         if (tty->driver->type == TTY_DRIVER_TYPE_PTY
282             && tty->driver->subtype == PTY_TYPE_MASTER)
283                 return;
284
285         buf = tty_audit_buf_get(tty);
286         if (!buf)
287                 return;
288
289         mutex_lock(&buf->mutex);
290         major = tty->driver->major;
291         minor = tty->driver->minor_start + tty->index;
292         if (buf->major != major || buf->minor != minor
293             || buf->icanon != tty->icanon) {
294                 tty_audit_buf_push_current(buf);
295                 buf->major = major;
296                 buf->minor = minor;
297                 buf->icanon = tty->icanon;
298         }
299         do {
300                 size_t run;
301
302                 run = N_TTY_BUF_SIZE - buf->valid;
303                 if (run > size)
304                         run = size;
305                 memcpy(buf->data + buf->valid, data, run);
306                 buf->valid += run;
307                 data += run;
308                 size -= run;
309                 if (buf->valid == N_TTY_BUF_SIZE)
310                         tty_audit_buf_push_current(buf);
311         } while (size != 0);
312         mutex_unlock(&buf->mutex);
313         tty_audit_buf_put(buf);
314 }
315
316 /**
317  *      tty_audit_push  -       Push buffered data out
318  *
319  *      Make sure no audit data is pending for @tty on the current process.
320  */
321 void tty_audit_push(struct tty_struct *tty)
322 {
323         struct tty_audit_buf *buf;
324
325         spin_lock_irq(&current->sighand->siglock);
326         if (likely(!current->signal->audit_tty)) {
327                 spin_unlock_irq(&current->sighand->siglock);
328                 return;
329         }
330         buf = current->signal->tty_audit_buf;
331         if (buf)
332                 atomic_inc(&buf->count);
333         spin_unlock_irq(&current->sighand->siglock);
334
335         if (buf) {
336                 int major, minor;
337
338                 major = tty->driver->major;
339                 minor = tty->driver->minor_start + tty->index;
340                 mutex_lock(&buf->mutex);
341                 if (buf->major == major && buf->minor == minor)
342                         tty_audit_buf_push_current(buf);
343                 mutex_unlock(&buf->mutex);
344                 tty_audit_buf_put(buf);
345         }
346 }