intel-iommu: Fix enabling snooping feature by mistake
[linux-2.6.git] / 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         buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
33         if (!buf->data)
34                 goto err_buf;
35         atomic_set(&buf->count, 1);
36         mutex_init(&buf->mutex);
37         buf->major = major;
38         buf->minor = minor;
39         buf->icanon = icanon;
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);
52         kfree(buf->data);
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
62 static void tty_audit_log(const char *description, struct task_struct *tsk,
63                           uid_t loginuid, unsigned sessionid, int major,
64                           int minor, unsigned char *data, size_t size)
65 {
66         struct audit_buffer *ab;
67
68         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
69         if (ab) {
70                 char name[sizeof(tsk->comm)];
71                 uid_t uid = task_uid(tsk);
72
73                 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
74                                  "major=%d minor=%d comm=", description,
75                                  tsk->pid, uid, loginuid, sessionid,
76                                  major, minor);
77                 get_task_comm(name, tsk);
78                 audit_log_untrustedstring(ab, name);
79                 audit_log_format(ab, " data=");
80                 audit_log_n_hex(ab, data, size);
81                 audit_log_end(ab);
82         }
83 }
84
85 /**
86  *      tty_audit_buf_push      -       Push buffered data out
87  *
88  *      Generate an audit message from the contents of @buf, which is owned by
89  *      @tsk with @loginuid.  @buf->mutex must be locked.
90  */
91 static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
92                                unsigned int sessionid,
93                                struct tty_audit_buf *buf)
94 {
95         if (buf->valid == 0)
96                 return;
97         if (audit_enabled == 0)
98                 return;
99         tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
100                       buf->data, buf->valid);
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 {
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);
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(&current->sighand->siglock);
128         buf = current->signal->tty_audit_buf;
129         current->signal->tty_audit_buf = NULL;
130         spin_unlock_irq(&current->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(&current->sighand->siglock);
149         sig->audit_tty = current->signal->audit_tty;
150         spin_unlock_irq(&current->sighand->siglock);
151         sig->tty_audit_buf = NULL;
152 }
153
154 /**
155  *      tty_audit_tiocsti       -       Log TIOCSTI
156  */
157 void 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  */
193 void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
194 {
195         struct tty_audit_buf *buf;
196
197         spin_lock_irq(&tsk->sighand->siglock);
198         buf = tsk->signal->tty_audit_buf;
199         if (buf)
200                 atomic_inc(&buf->count);
201         spin_unlock_irq(&tsk->sighand->siglock);
202         if (!buf)
203                 return;
204
205         mutex_lock(&buf->mutex);
206         tty_audit_buf_push(tsk, loginuid, sessionid, buf);
207         mutex_unlock(&buf->mutex);
208
209         tty_audit_buf_put(buf);
210 }
211
212 /**
213  *      tty_audit_buf_get       -       Get an audit buffer.
214  *
215  *      Get an audit buffer for @tty, allocate it if necessary.  Return %NULL
216  *      if TTY auditing is disabled or out of memory.  Otherwise, return a new
217  *      reference to the buffer.
218  */
219 static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
220 {
221         struct tty_audit_buf *buf, *buf2;
222
223         buf = NULL;
224         buf2 = NULL;
225         spin_lock_irq(&current->sighand->siglock);
226         if (likely(!current->signal->audit_tty))
227                 goto out;
228         buf = current->signal->tty_audit_buf;
229         if (buf) {
230                 atomic_inc(&buf->count);
231                 goto out;
232         }
233         spin_unlock_irq(&current->sighand->siglock);
234
235         buf2 = tty_audit_buf_alloc(tty->driver->major,
236                                    tty->driver->minor_start + tty->index,
237                                    tty->icanon);
238         if (buf2 == NULL) {
239                 audit_log_lost("out of memory in TTY auditing");
240                 return NULL;
241         }
242
243         spin_lock_irq(&current->sighand->siglock);
244         if (!current->signal->audit_tty)
245                 goto out;
246         buf = current->signal->tty_audit_buf;
247         if (!buf) {
248                 current->signal->tty_audit_buf = buf2;
249                 buf = buf2;
250                 buf2 = NULL;
251         }
252         atomic_inc(&buf->count);
253         /* Fall through */
254  out:
255         spin_unlock_irq(&current->sighand->siglock);
256         if (buf2)
257                 tty_audit_buf_free(buf2);
258         return buf;
259 }
260
261 /**
262  *      tty_audit_add_data      -       Add data for TTY auditing.
263  *
264  *      Audit @data of @size from @tty, if necessary.
265  */
266 void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
267                         size_t size)
268 {
269         struct tty_audit_buf *buf;
270         int major, minor;
271
272         if (unlikely(size == 0))
273                 return;
274
275         if (tty->driver->type == TTY_DRIVER_TYPE_PTY
276             && tty->driver->subtype == PTY_TYPE_MASTER)
277                 return;
278
279         buf = tty_audit_buf_get(tty);
280         if (!buf)
281                 return;
282
283         mutex_lock(&buf->mutex);
284         major = tty->driver->major;
285         minor = tty->driver->minor_start + tty->index;
286         if (buf->major != major || buf->minor != minor
287             || buf->icanon != tty->icanon) {
288                 tty_audit_buf_push_current(buf);
289                 buf->major = major;
290                 buf->minor = minor;
291                 buf->icanon = tty->icanon;
292         }
293         do {
294                 size_t run;
295
296                 run = N_TTY_BUF_SIZE - buf->valid;
297                 if (run > size)
298                         run = size;
299                 memcpy(buf->data + buf->valid, data, run);
300                 buf->valid += run;
301                 data += run;
302                 size -= run;
303                 if (buf->valid == N_TTY_BUF_SIZE)
304                         tty_audit_buf_push_current(buf);
305         } while (size != 0);
306         mutex_unlock(&buf->mutex);
307         tty_audit_buf_put(buf);
308 }
309
310 /**
311  *      tty_audit_push  -       Push buffered data out
312  *
313  *      Make sure no audit data is pending for @tty on the current process.
314  */
315 void tty_audit_push(struct tty_struct *tty)
316 {
317         struct tty_audit_buf *buf;
318
319         spin_lock_irq(&current->sighand->siglock);
320         if (likely(!current->signal->audit_tty)) {
321                 spin_unlock_irq(&current->sighand->siglock);
322                 return;
323         }
324         buf = current->signal->tty_audit_buf;
325         if (buf)
326                 atomic_inc(&buf->count);
327         spin_unlock_irq(&current->sighand->siglock);
328
329         if (buf) {
330                 int major, minor;
331
332                 major = tty->driver->major;
333                 minor = tty->driver->minor_start + tty->index;
334                 mutex_lock(&buf->mutex);
335                 if (buf->major == major && buf->minor == minor)
336                         tty_audit_buf_push_current(buf);
337                 mutex_unlock(&buf->mutex);
338                 tty_audit_buf_put(buf);
339         }
340 }