Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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> |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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 | |
Alan Cox | 66c6cea | 2008-02-08 04:18:46 -0800 | [diff] [blame] | 29 | buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 30 | if (!buf) |
| 31 | goto err; |
Alan Cox | c481c70 | 2009-06-11 13:04:27 +0100 | [diff] [blame] | 32 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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); |
Alan Cox | c481c70 | 2009-06-11 13:04:27 +0100 | [diff] [blame] | 52 | kfree(buf->data); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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 | |
Al Viro | 1e64174 | 2008-12-09 09:23:33 +0000 | [diff] [blame] | 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 | |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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, |
Eric Paris | 4746ec5 | 2008-01-08 10:06:53 -0500 | [diff] [blame] | 92 | unsigned int sessionid, |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 93 | struct tty_audit_buf *buf) |
| 94 | { |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 95 | if (buf->valid == 0) |
| 96 | return; |
| 97 | if (audit_enabled == 0) |
| 98 | return; |
Al Viro | 1e64174 | 2008-12-09 09:23:33 +0000 | [diff] [blame] | 99 | tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor, |
| 100 | buf->data, buf->valid); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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 | { |
Eric Paris | 4746ec5 | 2008-01-08 10:06:53 -0500 | [diff] [blame] | 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); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 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(¤t->sighand->siglock); |
| 128 | buf = current->signal->tty_audit_buf; |
| 129 | current->signal->tty_audit_buf = NULL; |
| 130 | spin_unlock_irq(¤t->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(¤t->sighand->siglock); |
| 149 | sig->audit_tty = current->signal->audit_tty; |
| 150 | spin_unlock_irq(¤t->sighand->siglock); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 151 | } |
| 152 | |
| 153 | /** |
Al Viro | 1e64174 | 2008-12-09 09:23:33 +0000 | [diff] [blame] | 154 | * tty_audit_tiocsti - Log TIOCSTI |
| 155 | */ |
| 156 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) |
| 157 | { |
| 158 | struct tty_audit_buf *buf; |
| 159 | int major, minor, should_audit; |
| 160 | |
| 161 | spin_lock_irq(¤t->sighand->siglock); |
| 162 | should_audit = current->signal->audit_tty; |
| 163 | buf = current->signal->tty_audit_buf; |
| 164 | if (buf) |
| 165 | atomic_inc(&buf->count); |
| 166 | spin_unlock_irq(¤t->sighand->siglock); |
| 167 | |
| 168 | major = tty->driver->major; |
| 169 | minor = tty->driver->minor_start + tty->index; |
| 170 | if (buf) { |
| 171 | mutex_lock(&buf->mutex); |
| 172 | if (buf->major == major && buf->minor == minor) |
| 173 | tty_audit_buf_push_current(buf); |
| 174 | mutex_unlock(&buf->mutex); |
| 175 | tty_audit_buf_put(buf); |
| 176 | } |
| 177 | |
| 178 | if (should_audit && audit_enabled) { |
| 179 | uid_t auid; |
| 180 | unsigned int sessionid; |
| 181 | |
| 182 | auid = audit_get_loginuid(current); |
| 183 | sessionid = audit_get_sessionid(current); |
| 184 | tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major, |
| 185 | minor, &ch, 1); |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | /** |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 190 | * tty_audit_push_task - Flush task's pending audit data |
| 191 | */ |
Eric Paris | 2532386 | 2008-04-18 10:09:25 -0400 | [diff] [blame] | 192 | void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid) |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 193 | { |
| 194 | struct tty_audit_buf *buf; |
| 195 | |
| 196 | spin_lock_irq(&tsk->sighand->siglock); |
| 197 | buf = tsk->signal->tty_audit_buf; |
| 198 | if (buf) |
| 199 | atomic_inc(&buf->count); |
| 200 | spin_unlock_irq(&tsk->sighand->siglock); |
| 201 | if (!buf) |
| 202 | return; |
| 203 | |
| 204 | mutex_lock(&buf->mutex); |
Eric Paris | 4746ec5 | 2008-01-08 10:06:53 -0500 | [diff] [blame] | 205 | tty_audit_buf_push(tsk, loginuid, sessionid, buf); |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 206 | mutex_unlock(&buf->mutex); |
| 207 | |
| 208 | tty_audit_buf_put(buf); |
| 209 | } |
| 210 | |
| 211 | /** |
| 212 | * tty_audit_buf_get - Get an audit buffer. |
| 213 | * |
| 214 | * Get an audit buffer for @tty, allocate it if necessary. Return %NULL |
| 215 | * if TTY auditing is disabled or out of memory. Otherwise, return a new |
| 216 | * reference to the buffer. |
| 217 | */ |
| 218 | static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty) |
| 219 | { |
| 220 | struct tty_audit_buf *buf, *buf2; |
| 221 | |
| 222 | buf = NULL; |
| 223 | buf2 = NULL; |
| 224 | spin_lock_irq(¤t->sighand->siglock); |
| 225 | if (likely(!current->signal->audit_tty)) |
| 226 | goto out; |
| 227 | buf = current->signal->tty_audit_buf; |
| 228 | if (buf) { |
| 229 | atomic_inc(&buf->count); |
| 230 | goto out; |
| 231 | } |
| 232 | spin_unlock_irq(¤t->sighand->siglock); |
| 233 | |
| 234 | buf2 = tty_audit_buf_alloc(tty->driver->major, |
| 235 | tty->driver->minor_start + tty->index, |
| 236 | tty->icanon); |
| 237 | if (buf2 == NULL) { |
| 238 | audit_log_lost("out of memory in TTY auditing"); |
| 239 | return NULL; |
| 240 | } |
| 241 | |
| 242 | spin_lock_irq(¤t->sighand->siglock); |
| 243 | if (!current->signal->audit_tty) |
| 244 | goto out; |
| 245 | buf = current->signal->tty_audit_buf; |
| 246 | if (!buf) { |
| 247 | current->signal->tty_audit_buf = buf2; |
| 248 | buf = buf2; |
| 249 | buf2 = NULL; |
| 250 | } |
| 251 | atomic_inc(&buf->count); |
| 252 | /* Fall through */ |
| 253 | out: |
| 254 | spin_unlock_irq(¤t->sighand->siglock); |
| 255 | if (buf2) |
| 256 | tty_audit_buf_free(buf2); |
| 257 | return buf; |
| 258 | } |
| 259 | |
| 260 | /** |
| 261 | * tty_audit_add_data - Add data for TTY auditing. |
| 262 | * |
| 263 | * Audit @data of @size from @tty, if necessary. |
| 264 | */ |
| 265 | void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, |
| 266 | size_t size) |
| 267 | { |
| 268 | struct tty_audit_buf *buf; |
| 269 | int major, minor; |
| 270 | |
| 271 | if (unlikely(size == 0)) |
| 272 | return; |
| 273 | |
Miloslav Trmac | 4112622 | 2008-04-18 13:30:14 -0700 | [diff] [blame] | 274 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
| 275 | && tty->driver->subtype == PTY_TYPE_MASTER) |
| 276 | return; |
| 277 | |
Miloslav Trmac | 522ed77 | 2007-07-15 23:40:56 -0700 | [diff] [blame] | 278 | buf = tty_audit_buf_get(tty); |
| 279 | if (!buf) |
| 280 | return; |
| 281 | |
| 282 | mutex_lock(&buf->mutex); |
| 283 | major = tty->driver->major; |
| 284 | minor = tty->driver->minor_start + tty->index; |
| 285 | if (buf->major != major || buf->minor != minor |
| 286 | || buf->icanon != tty->icanon) { |
| 287 | tty_audit_buf_push_current(buf); |
| 288 | buf->major = major; |
| 289 | buf->minor = minor; |
| 290 | buf->icanon = tty->icanon; |
| 291 | } |
| 292 | do { |
| 293 | size_t run; |
| 294 | |
| 295 | run = N_TTY_BUF_SIZE - buf->valid; |
| 296 | if (run > size) |
| 297 | run = size; |
| 298 | memcpy(buf->data + buf->valid, data, run); |
| 299 | buf->valid += run; |
| 300 | data += run; |
| 301 | size -= run; |
| 302 | if (buf->valid == N_TTY_BUF_SIZE) |
| 303 | tty_audit_buf_push_current(buf); |
| 304 | } while (size != 0); |
| 305 | mutex_unlock(&buf->mutex); |
| 306 | tty_audit_buf_put(buf); |
| 307 | } |
| 308 | |
| 309 | /** |
| 310 | * tty_audit_push - Push buffered data out |
| 311 | * |
| 312 | * Make sure no audit data is pending for @tty on the current process. |
| 313 | */ |
| 314 | void tty_audit_push(struct tty_struct *tty) |
| 315 | { |
| 316 | struct tty_audit_buf *buf; |
| 317 | |
| 318 | spin_lock_irq(¤t->sighand->siglock); |
| 319 | if (likely(!current->signal->audit_tty)) { |
| 320 | spin_unlock_irq(¤t->sighand->siglock); |
| 321 | return; |
| 322 | } |
| 323 | buf = current->signal->tty_audit_buf; |
| 324 | if (buf) |
| 325 | atomic_inc(&buf->count); |
| 326 | spin_unlock_irq(¤t->sighand->siglock); |
| 327 | |
| 328 | if (buf) { |
| 329 | int major, minor; |
| 330 | |
| 331 | major = tty->driver->major; |
| 332 | minor = tty->driver->minor_start + tty->index; |
| 333 | mutex_lock(&buf->mutex); |
| 334 | if (buf->major == major && buf->minor == minor) |
| 335 | tty_audit_buf_push_current(buf); |
| 336 | mutex_unlock(&buf->mutex); |
| 337 | tty_audit_buf_put(buf); |
| 338 | } |
| 339 | } |