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e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-2.0 |
522ed776 MT |
2 | /* |
3 | * Creating audit events from TTY input. | |
4 | * | |
e5656d43 | 5 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. |
522ed776 MT |
6 | * |
7 | * Authors: Miloslav Trmac <mitr@redhat.com> | |
8 | */ | |
9 | ||
10 | #include <linux/audit.h> | |
5a0e3ad6 | 11 | #include <linux/slab.h> |
522ed776 MT |
12 | #include <linux/tty.h> |
13 | ||
14 | struct tty_audit_buf { | |
522ed776 | 15 | struct mutex mutex; /* Protects all data below */ |
4d240b64 | 16 | dev_t dev; /* The TTY which the data is from */ |
522ed776 MT |
17 | unsigned icanon:1; |
18 | size_t valid; | |
19 | unsigned char *data; /* Allocated size N_TTY_BUF_SIZE */ | |
20 | }; | |
21 | ||
55b6314a PH |
22 | static struct tty_audit_buf *tty_audit_buf_ref(void) |
23 | { | |
24 | struct tty_audit_buf *buf; | |
25 | ||
26 | buf = current->signal->tty_audit_buf; | |
27 | WARN_ON(buf == ERR_PTR(-ESRCH)); | |
28 | return buf; | |
29 | } | |
30 | ||
a75c9b09 | 31 | static struct tty_audit_buf *tty_audit_buf_alloc(void) |
522ed776 MT |
32 | { |
33 | struct tty_audit_buf *buf; | |
34 | ||
66c6ceae | 35 | buf = kmalloc(sizeof(*buf), GFP_KERNEL); |
522ed776 MT |
36 | if (!buf) |
37 | goto err; | |
c481c707 | 38 | buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
522ed776 MT |
39 | if (!buf->data) |
40 | goto err_buf; | |
522ed776 | 41 | mutex_init(&buf->mutex); |
4d240b64 | 42 | buf->dev = MKDEV(0, 0); |
a75c9b09 | 43 | buf->icanon = 0; |
522ed776 MT |
44 | buf->valid = 0; |
45 | return buf; | |
46 | ||
47 | err_buf: | |
48 | kfree(buf); | |
49 | err: | |
50 | return NULL; | |
51 | } | |
52 | ||
53 | static void tty_audit_buf_free(struct tty_audit_buf *buf) | |
54 | { | |
55 | WARN_ON(buf->valid != 0); | |
c481c707 | 56 | kfree(buf->data); |
522ed776 MT |
57 | kfree(buf); |
58 | } | |
59 | ||
4d240b64 | 60 | static void tty_audit_log(const char *description, dev_t dev, |
152f497b | 61 | unsigned char *data, size_t size) |
522ed776 MT |
62 | { |
63 | struct audit_buffer *ab; | |
152f497b | 64 | struct task_struct *tsk = current; |
f1dc4867 | 65 | pid_t pid = task_pid_nr(tsk); |
152f497b EP |
66 | uid_t uid = from_kuid(&init_user_ns, task_uid(tsk)); |
67 | uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk)); | |
4440e854 | 68 | unsigned int sessionid = audit_get_sessionid(tsk); |
522ed776 | 69 | |
522ed776 MT |
70 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); |
71 | if (ab) { | |
72 | char name[sizeof(tsk->comm)]; | |
152f497b EP |
73 | |
74 | audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" | |
f1dc4867 | 75 | " minor=%d comm=", description, pid, uid, |
4d240b64 | 76 | loginuid, sessionid, MAJOR(dev), MINOR(dev)); |
522ed776 MT |
77 | get_task_comm(name, tsk); |
78 | audit_log_untrustedstring(ab, name); | |
79 | audit_log_format(ab, " data="); | |
1e641743 | 80 | audit_log_n_hex(ab, data, size); |
522ed776 MT |
81 | audit_log_end(ab); |
82 | } | |
1e641743 AV |
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 | |
152f497b | 89 | * the current task. @buf->mutex must be locked. |
1e641743 | 90 | */ |
152f497b | 91 | static void tty_audit_buf_push(struct tty_audit_buf *buf) |
1e641743 AV |
92 | { |
93 | if (buf->valid == 0) | |
94 | return; | |
f7859590 | 95 | if (audit_enabled == AUDIT_OFF) { |
00bff392 | 96 | buf->valid = 0; |
1e641743 | 97 | return; |
00bff392 | 98 | } |
4d240b64 | 99 | tty_audit_log("tty", buf->dev, buf->data, buf->valid); |
522ed776 MT |
100 | buf->valid = 0; |
101 | } | |
102 | ||
522ed776 MT |
103 | /** |
104 | * tty_audit_exit - Handle a task exit | |
105 | * | |
106 | * Make sure all buffered data is written out and deallocate the buffer. | |
107 | * Only needs to be called if current->signal->tty_audit_buf != %NULL. | |
5493090f PH |
108 | * |
109 | * The process is single-threaded at this point; no other threads share | |
110 | * current->signal. | |
522ed776 MT |
111 | */ |
112 | void tty_audit_exit(void) | |
113 | { | |
114 | struct tty_audit_buf *buf; | |
115 | ||
55b6314a | 116 | buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH)); |
522ed776 MT |
117 | if (!buf) |
118 | return; | |
119 | ||
152f497b | 120 | tty_audit_buf_push(buf); |
5493090f | 121 | tty_audit_buf_free(buf); |
522ed776 MT |
122 | } |
123 | ||
124 | /** | |
125 | * tty_audit_fork - Copy TTY audit state for a new task | |
126 | * | |
127 | * Set up TTY audit state in @sig from current. @sig needs no locking. | |
128 | */ | |
129 | void tty_audit_fork(struct signal_struct *sig) | |
130 | { | |
522ed776 | 131 | sig->audit_tty = current->signal->audit_tty; |
522ed776 MT |
132 | } |
133 | ||
1e641743 AV |
134 | /** |
135 | * tty_audit_tiocsti - Log TIOCSTI | |
136 | */ | |
137 | void tty_audit_tiocsti(struct tty_struct *tty, char ch) | |
138 | { | |
4d240b64 | 139 | dev_t dev; |
1e641743 | 140 | |
4d240b64 | 141 | dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; |
82b5c93a PH |
142 | if (tty_audit_push()) |
143 | return; | |
1e641743 | 144 | |
54555919 | 145 | if (audit_enabled) |
4d240b64 | 146 | tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1); |
1e641743 AV |
147 | } |
148 | ||
522ed776 | 149 | /** |
37282a77 | 150 | * tty_audit_push - Flush current's pending audit data |
3c80fe4a | 151 | * |
37282a77 | 152 | * Returns 0 if success, -EPERM if tty audit is disabled |
522ed776 | 153 | */ |
37282a77 | 154 | int tty_audit_push(void) |
522ed776 | 155 | { |
2e28d38a | 156 | struct tty_audit_buf *buf; |
522ed776 | 157 | |
2e28d38a PH |
158 | if (~current->signal->audit_tty & AUDIT_TTY_ENABLE) |
159 | return -EPERM; | |
160 | ||
55b6314a PH |
161 | buf = tty_audit_buf_ref(); |
162 | if (!IS_ERR_OR_NULL(buf)) { | |
2e28d38a PH |
163 | mutex_lock(&buf->mutex); |
164 | tty_audit_buf_push(buf); | |
165 | mutex_unlock(&buf->mutex); | |
2e28d38a | 166 | } |
3c80fe4a | 167 | return 0; |
522ed776 MT |
168 | } |
169 | ||
170 | /** | |
171 | * tty_audit_buf_get - Get an audit buffer. | |
172 | * | |
a75c9b09 | 173 | * Get an audit buffer, allocate it if necessary. Return %NULL |
55b6314a PH |
174 | * if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already |
175 | * occurred. Otherwise, return a new reference to the buffer. | |
522ed776 | 176 | */ |
a75c9b09 | 177 | static struct tty_audit_buf *tty_audit_buf_get(void) |
522ed776 | 178 | { |
fbaa1227 | 179 | struct tty_audit_buf *buf; |
522ed776 | 180 | |
55b6314a | 181 | buf = tty_audit_buf_ref(); |
5493090f PH |
182 | if (buf) |
183 | return buf; | |
522ed776 | 184 | |
fbaa1227 PH |
185 | buf = tty_audit_buf_alloc(); |
186 | if (buf == NULL) { | |
522ed776 MT |
187 | audit_log_lost("out of memory in TTY auditing"); |
188 | return NULL; | |
189 | } | |
190 | ||
fbaa1227 PH |
191 | /* Race to use this buffer, free it if another wins */ |
192 | if (cmpxchg(¤t->signal->tty_audit_buf, NULL, buf) != NULL) | |
193 | tty_audit_buf_free(buf); | |
55b6314a | 194 | return tty_audit_buf_ref(); |
522ed776 MT |
195 | } |
196 | ||
197 | /** | |
198 | * tty_audit_add_data - Add data for TTY auditing. | |
199 | * | |
200 | * Audit @data of @size from @tty, if necessary. | |
201 | */ | |
309426ae | 202 | void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size) |
522ed776 MT |
203 | { |
204 | struct tty_audit_buf *buf; | |
309426ae | 205 | unsigned int icanon = !!L_ICANON(tty); |
2e28d38a | 206 | unsigned int audit_tty; |
4d240b64 | 207 | dev_t dev; |
522ed776 | 208 | |
f17c3662 PH |
209 | audit_tty = READ_ONCE(current->signal->audit_tty); |
210 | if (~audit_tty & AUDIT_TTY_ENABLE) | |
211 | return; | |
212 | ||
522ed776 MT |
213 | if (unlikely(size == 0)) |
214 | return; | |
215 | ||
d7c0ba40 PH |
216 | if (tty->driver->type == TTY_DRIVER_TYPE_PTY |
217 | && tty->driver->subtype == PTY_TYPE_MASTER) | |
218 | return; | |
219 | ||
2e28d38a | 220 | if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty)) |
46e959ea RGB |
221 | return; |
222 | ||
a75c9b09 | 223 | buf = tty_audit_buf_get(); |
55b6314a | 224 | if (IS_ERR_OR_NULL(buf)) |
522ed776 MT |
225 | return; |
226 | ||
227 | mutex_lock(&buf->mutex); | |
4d240b64 PH |
228 | dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; |
229 | if (buf->dev != dev || buf->icanon != icanon) { | |
152f497b | 230 | tty_audit_buf_push(buf); |
4d240b64 | 231 | buf->dev = dev; |
6c633f27 | 232 | buf->icanon = icanon; |
522ed776 MT |
233 | } |
234 | do { | |
235 | size_t run; | |
236 | ||
237 | run = N_TTY_BUF_SIZE - buf->valid; | |
238 | if (run > size) | |
239 | run = size; | |
240 | memcpy(buf->data + buf->valid, data, run); | |
241 | buf->valid += run; | |
242 | data += run; | |
243 | size -= run; | |
244 | if (buf->valid == N_TTY_BUF_SIZE) | |
152f497b | 245 | tty_audit_buf_push(buf); |
522ed776 MT |
246 | } while (size != 0); |
247 | mutex_unlock(&buf->mutex); | |
522ed776 | 248 | } |