2 * Creating audit events from TTY input.
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
9 * Authors: Miloslav Trmac <mitr@redhat.com>
12 #include <linux/audit.h>
13 #include <linux/slab.h>
14 #include <linux/tty.h>
16 struct tty_audit_buf {
18 struct mutex mutex; /* Protects all data below */
19 int major, minor; /* The TTY which the data is from */
22 unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */
25 static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
28 struct tty_audit_buf *buf;
30 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
33 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
36 atomic_set(&buf->count, 1);
37 mutex_init(&buf->mutex);
50 static void tty_audit_buf_free(struct tty_audit_buf *buf)
52 WARN_ON(buf->valid != 0);
57 static void tty_audit_buf_put(struct tty_audit_buf *buf)
59 if (atomic_dec_and_test(&buf->count))
60 tty_audit_buf_free(buf);
63 static void tty_audit_log(const char *description, int major, int minor,
64 unsigned char *data, size_t size)
66 struct audit_buffer *ab;
67 struct task_struct *tsk = current;
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 u32 sessionid = audit_get_sessionid(tsk);
72 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
74 char name[sizeof(tsk->comm)];
76 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
77 " minor=%d comm=", description, tsk->pid, uid,
78 loginuid, sessionid, major, minor);
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);
88 * tty_audit_buf_push - Push buffered data out
90 * Generate an audit message from the contents of @buf, which is owned by
91 * the current task. @buf->mutex must be locked.
93 static void tty_audit_buf_push(struct tty_audit_buf *buf)
97 if (audit_enabled == 0) {
101 tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
106 * tty_audit_exit - Handle a task exit
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.
111 void tty_audit_exit(void)
113 struct tty_audit_buf *buf;
116 spin_lock_irqsave(¤t->sighand->siglock, flags);
117 buf = current->signal->tty_audit_buf;
118 current->signal->tty_audit_buf = NULL;
119 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
123 mutex_lock(&buf->mutex);
124 tty_audit_buf_push(buf);
125 mutex_unlock(&buf->mutex);
127 tty_audit_buf_put(buf);
131 * tty_audit_fork - Copy TTY audit state for a new task
133 * Set up TTY audit state in @sig from current. @sig needs no locking.
135 void tty_audit_fork(struct signal_struct *sig)
139 spin_lock_irqsave(¤t->sighand->siglock, flags);
140 sig->audit_tty = current->signal->audit_tty;
141 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
145 * tty_audit_tiocsti - Log TIOCSTI
147 void tty_audit_tiocsti(struct tty_struct *tty, char ch)
149 struct tty_audit_buf *buf;
150 int major, minor, should_audit;
153 spin_lock_irqsave(¤t->sighand->siglock, flags);
154 should_audit = current->signal->audit_tty;
155 buf = current->signal->tty_audit_buf;
157 atomic_inc(&buf->count);
158 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
160 major = tty->driver->major;
161 minor = tty->driver->minor_start + tty->index;
163 mutex_lock(&buf->mutex);
164 if (buf->major == major && buf->minor == minor)
165 tty_audit_buf_push(buf);
166 mutex_unlock(&buf->mutex);
167 tty_audit_buf_put(buf);
170 if (should_audit && audit_enabled) {
172 unsigned int sessionid;
174 auid = audit_get_loginuid(current);
175 sessionid = audit_get_sessionid(current);
176 tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1);
181 * tty_audit_push_current - Flush current's pending audit data
183 * Try to lock sighand and get a reference to the tty audit buffer if available.
184 * Flush the buffer or return an appropriate error code.
186 int tty_audit_push_current(void)
188 struct tty_audit_buf *buf = ERR_PTR(-EPERM);
189 struct task_struct *tsk = current;
192 if (!lock_task_sighand(tsk, &flags))
195 if (tsk->signal->audit_tty) {
196 buf = tsk->signal->tty_audit_buf;
198 atomic_inc(&buf->count);
200 unlock_task_sighand(tsk, &flags);
203 * Return 0 when signal->audit_tty set
204 * but tsk->signal->tty_audit_buf == NULL.
206 if (!buf || IS_ERR(buf))
209 mutex_lock(&buf->mutex);
210 tty_audit_buf_push(buf);
211 mutex_unlock(&buf->mutex);
213 tty_audit_buf_put(buf);
218 * tty_audit_buf_get - Get an audit buffer.
220 * Get an audit buffer for @tty, allocate it if necessary. Return %NULL
221 * if TTY auditing is disabled or out of memory. Otherwise, return a new
222 * reference to the buffer.
224 static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
227 struct tty_audit_buf *buf, *buf2;
232 spin_lock_irqsave(¤t->sighand->siglock, flags);
233 if (likely(!current->signal->audit_tty))
235 buf = current->signal->tty_audit_buf;
237 atomic_inc(&buf->count);
240 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
242 buf2 = tty_audit_buf_alloc(tty->driver->major,
243 tty->driver->minor_start + tty->index,
246 audit_log_lost("out of memory in TTY auditing");
250 spin_lock_irqsave(¤t->sighand->siglock, flags);
251 if (!current->signal->audit_tty)
253 buf = current->signal->tty_audit_buf;
255 current->signal->tty_audit_buf = buf2;
259 atomic_inc(&buf->count);
262 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
264 tty_audit_buf_free(buf2);
269 * tty_audit_add_data - Add data for TTY auditing.
271 * Audit @data of @size from @tty, if necessary.
273 void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
274 size_t size, unsigned icanon)
276 struct tty_audit_buf *buf;
279 if (unlikely(size == 0))
282 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
283 && tty->driver->subtype == PTY_TYPE_MASTER)
286 buf = tty_audit_buf_get(tty, icanon);
290 mutex_lock(&buf->mutex);
291 major = tty->driver->major;
292 minor = tty->driver->minor_start + tty->index;
293 if (buf->major != major || buf->minor != minor
294 || buf->icanon != icanon) {
295 tty_audit_buf_push(buf);
298 buf->icanon = icanon;
303 run = N_TTY_BUF_SIZE - buf->valid;
306 memcpy(buf->data + buf->valid, data, run);
310 if (buf->valid == N_TTY_BUF_SIZE)
311 tty_audit_buf_push(buf);
313 mutex_unlock(&buf->mutex);
314 tty_audit_buf_put(buf);
318 * tty_audit_push - Push buffered data out
320 * Make sure no audit data is pending for @tty on the current process.
322 void tty_audit_push(struct tty_struct *tty)
324 struct tty_audit_buf *buf;
327 spin_lock_irqsave(¤t->sighand->siglock, flags);
328 if (likely(!current->signal->audit_tty)) {
329 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
332 buf = current->signal->tty_audit_buf;
334 atomic_inc(&buf->count);
335 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
340 major = tty->driver->major;
341 minor = tty->driver->minor_start + tty->index;
342 mutex_lock(&buf->mutex);
343 if (buf->major == major && buf->minor == minor)
344 tty_audit_buf_push(buf);
345 mutex_unlock(&buf->mutex);
346 tty_audit_buf_put(buf);