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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Creating audit events from TTY input.
4 *
5 * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
6 *
7 * Authors: Miloslav Trmac <mitr@redhat.com>
8 */
9
10#include <linux/audit.h>
11#include <linux/slab.h>
12#include <linux/tty.h>
13#include "tty.h"
14
15struct tty_audit_buf {
16 struct mutex mutex; /* Protects all data below */
17 dev_t dev; /* The TTY which the data is from */
18 bool icanon;
19 size_t valid;
20 u8 *data; /* Allocated size N_TTY_BUF_SIZE */
21};
22
23static struct tty_audit_buf *tty_audit_buf_ref(void)
24{
25 struct tty_audit_buf *buf;
26
27 buf = current->signal->tty_audit_buf;
28 WARN_ON(buf == ERR_PTR(-ESRCH));
29 return buf;
30}
31
32static struct tty_audit_buf *tty_audit_buf_alloc(void)
33{
34 struct tty_audit_buf *buf;
35
36 buf = kzalloc(sizeof(*buf), GFP_KERNEL);
37 if (!buf)
38 goto err;
39
40 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
41 if (!buf->data)
42 goto err_buf;
43
44 mutex_init(&buf->mutex);
45
46 return buf;
47
48err_buf:
49 kfree(buf);
50err:
51 return NULL;
52}
53
54static void tty_audit_buf_free(struct tty_audit_buf *buf)
55{
56 WARN_ON(buf->valid != 0);
57 kfree(buf->data);
58 kfree(buf);
59}
60
61static void tty_audit_log(const char *description, dev_t dev,
62 const u8 *data, size_t size)
63{
64 struct audit_buffer *ab;
65 pid_t pid = task_pid_nr(current);
66 uid_t uid = from_kuid(&init_user_ns, task_uid(current));
67 uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));
68 unsigned int sessionid = audit_get_sessionid(current);
69 char name[TASK_COMM_LEN];
70
71 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_TTY);
72 if (!ab)
73 return;
74
75 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d minor=%d comm=",
76 description, pid, uid, loginuid, sessionid,
77 MAJOR(dev), MINOR(dev));
78 get_task_comm(name, current);
79 audit_log_untrustedstring(ab, name);
80 audit_log_format(ab, " data=");
81 audit_log_n_hex(ab, data, size);
82 audit_log_end(ab);
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 * the current task. @buf->mutex must be locked.
90 */
91static void tty_audit_buf_push(struct tty_audit_buf *buf)
92{
93 if (buf->valid == 0)
94 return;
95 if (audit_enabled == AUDIT_OFF) {
96 buf->valid = 0;
97 return;
98 }
99 tty_audit_log("tty", buf->dev, buf->data, buf->valid);
100 buf->valid = 0;
101}
102
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.
108 *
109 * The process is single-threaded at this point; no other threads share
110 * current->signal.
111 */
112void tty_audit_exit(void)
113{
114 struct tty_audit_buf *buf;
115
116 buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH));
117 if (!buf)
118 return;
119
120 tty_audit_buf_push(buf);
121 tty_audit_buf_free(buf);
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 */
129void tty_audit_fork(struct signal_struct *sig)
130{
131 sig->audit_tty = current->signal->audit_tty;
132}
133
134/*
135 * tty_audit_tiocsti - Log TIOCSTI
136 */
137void tty_audit_tiocsti(const struct tty_struct *tty, u8 ch)
138{
139 dev_t dev;
140
141 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
142 if (tty_audit_push())
143 return;
144
145 if (audit_enabled)
146 tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1);
147}
148
149/*
150 * tty_audit_push - Flush current's pending audit data
151 *
152 * Returns 0 if success, -EPERM if tty audit is disabled
153 */
154int tty_audit_push(void)
155{
156 struct tty_audit_buf *buf;
157
158 if (~current->signal->audit_tty & AUDIT_TTY_ENABLE)
159 return -EPERM;
160
161 buf = tty_audit_buf_ref();
162 if (!IS_ERR_OR_NULL(buf)) {
163 mutex_lock(&buf->mutex);
164 tty_audit_buf_push(buf);
165 mutex_unlock(&buf->mutex);
166 }
167 return 0;
168}
169
170/*
171 * tty_audit_buf_get - Get an audit buffer.
172 *
173 * Get an audit buffer, allocate it if necessary. Return %NULL
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.
176 */
177static struct tty_audit_buf *tty_audit_buf_get(void)
178{
179 struct tty_audit_buf *buf;
180
181 buf = tty_audit_buf_ref();
182 if (buf)
183 return buf;
184
185 buf = tty_audit_buf_alloc();
186 if (buf == NULL) {
187 audit_log_lost("out of memory in TTY auditing");
188 return NULL;
189 }
190
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);
194 return tty_audit_buf_ref();
195}
196
197/*
198 * tty_audit_add_data - Add data for TTY auditing.
199 *
200 * Audit @data of @size from @tty, if necessary.
201 */
202void tty_audit_add_data(const struct tty_struct *tty, const void *data,
203 size_t size)
204{
205 struct tty_audit_buf *buf;
206 unsigned int audit_tty;
207 bool icanon = L_ICANON(tty);
208 dev_t dev;
209
210 audit_tty = READ_ONCE(current->signal->audit_tty);
211 if (~audit_tty & AUDIT_TTY_ENABLE)
212 return;
213
214 if (unlikely(size == 0))
215 return;
216
217 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
218 && tty->driver->subtype == PTY_TYPE_MASTER)
219 return;
220
221 if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty))
222 return;
223
224 buf = tty_audit_buf_get();
225 if (IS_ERR_OR_NULL(buf))
226 return;
227
228 mutex_lock(&buf->mutex);
229 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
230 if (buf->dev != dev || buf->icanon != icanon) {
231 tty_audit_buf_push(buf);
232 buf->dev = dev;
233 buf->icanon = icanon;
234 }
235 do {
236 size_t run;
237
238 run = N_TTY_BUF_SIZE - buf->valid;
239 if (run > size)
240 run = size;
241 memcpy(buf->data + buf->valid, data, run);
242 buf->valid += run;
243 data += run;
244 size -= run;
245 if (buf->valid == N_TTY_BUF_SIZE)
246 tty_audit_buf_push(buf);
247 } while (size != 0);
248 mutex_unlock(&buf->mutex);
249}
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/slab.h>
14#include <linux/tty.h>
15
16struct tty_audit_buf {
17 struct mutex mutex; /* Protects all data below */
18 dev_t dev; /* 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
24static struct tty_audit_buf *tty_audit_buf_ref(void)
25{
26 struct tty_audit_buf *buf;
27
28 buf = current->signal->tty_audit_buf;
29 WARN_ON(buf == ERR_PTR(-ESRCH));
30 return buf;
31}
32
33static struct tty_audit_buf *tty_audit_buf_alloc(void)
34{
35 struct tty_audit_buf *buf;
36
37 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
38 if (!buf)
39 goto err;
40 buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
41 if (!buf->data)
42 goto err_buf;
43 mutex_init(&buf->mutex);
44 buf->dev = MKDEV(0, 0);
45 buf->icanon = 0;
46 buf->valid = 0;
47 return buf;
48
49err_buf:
50 kfree(buf);
51err:
52 return NULL;
53}
54
55static void tty_audit_buf_free(struct tty_audit_buf *buf)
56{
57 WARN_ON(buf->valid != 0);
58 kfree(buf->data);
59 kfree(buf);
60}
61
62static void tty_audit_log(const char *description, dev_t dev,
63 unsigned char *data, size_t size)
64{
65 struct audit_buffer *ab;
66 struct task_struct *tsk = current;
67 pid_t pid = task_pid_nr(tsk);
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 unsigned int sessionid = audit_get_sessionid(tsk);
71
72 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
73 if (ab) {
74 char name[sizeof(tsk->comm)];
75
76 audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
77 " minor=%d comm=", description, pid, uid,
78 loginuid, sessionid, MAJOR(dev), MINOR(dev));
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);
83 audit_log_end(ab);
84 }
85}
86
87/**
88 * tty_audit_buf_push - Push buffered data out
89 *
90 * Generate an audit message from the contents of @buf, which is owned by
91 * the current task. @buf->mutex must be locked.
92 */
93static void tty_audit_buf_push(struct tty_audit_buf *buf)
94{
95 if (buf->valid == 0)
96 return;
97 if (audit_enabled == 0) {
98 buf->valid = 0;
99 return;
100 }
101 tty_audit_log("tty", buf->dev, buf->data, buf->valid);
102 buf->valid = 0;
103}
104
105/**
106 * tty_audit_exit - Handle a task exit
107 *
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.
110 *
111 * The process is single-threaded at this point; no other threads share
112 * current->signal.
113 */
114void tty_audit_exit(void)
115{
116 struct tty_audit_buf *buf;
117
118 buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH));
119 if (!buf)
120 return;
121
122 tty_audit_buf_push(buf);
123 tty_audit_buf_free(buf);
124}
125
126/**
127 * tty_audit_fork - Copy TTY audit state for a new task
128 *
129 * Set up TTY audit state in @sig from current. @sig needs no locking.
130 */
131void tty_audit_fork(struct signal_struct *sig)
132{
133 sig->audit_tty = current->signal->audit_tty;
134}
135
136/**
137 * tty_audit_tiocsti - Log TIOCSTI
138 */
139void tty_audit_tiocsti(struct tty_struct *tty, char ch)
140{
141 dev_t dev;
142
143 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
144 if (tty_audit_push())
145 return;
146
147 if (audit_enabled)
148 tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1);
149}
150
151/**
152 * tty_audit_push - Flush current's pending audit data
153 *
154 * Returns 0 if success, -EPERM if tty audit is disabled
155 */
156int tty_audit_push(void)
157{
158 struct tty_audit_buf *buf;
159
160 if (~current->signal->audit_tty & AUDIT_TTY_ENABLE)
161 return -EPERM;
162
163 buf = tty_audit_buf_ref();
164 if (!IS_ERR_OR_NULL(buf)) {
165 mutex_lock(&buf->mutex);
166 tty_audit_buf_push(buf);
167 mutex_unlock(&buf->mutex);
168 }
169 return 0;
170}
171
172/**
173 * tty_audit_buf_get - Get an audit buffer.
174 *
175 * Get an audit buffer, allocate it if necessary. Return %NULL
176 * if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already
177 * occurred. Otherwise, return a new reference to the buffer.
178 */
179static struct tty_audit_buf *tty_audit_buf_get(void)
180{
181 struct tty_audit_buf *buf;
182
183 buf = tty_audit_buf_ref();
184 if (buf)
185 return buf;
186
187 buf = tty_audit_buf_alloc();
188 if (buf == NULL) {
189 audit_log_lost("out of memory in TTY auditing");
190 return NULL;
191 }
192
193 /* Race to use this buffer, free it if another wins */
194 if (cmpxchg(¤t->signal->tty_audit_buf, NULL, buf) != NULL)
195 tty_audit_buf_free(buf);
196 return tty_audit_buf_ref();
197}
198
199/**
200 * tty_audit_add_data - Add data for TTY auditing.
201 *
202 * Audit @data of @size from @tty, if necessary.
203 */
204void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size)
205{
206 struct tty_audit_buf *buf;
207 unsigned int icanon = !!L_ICANON(tty);
208 unsigned int audit_tty;
209 dev_t dev;
210
211 audit_tty = READ_ONCE(current->signal->audit_tty);
212 if (~audit_tty & AUDIT_TTY_ENABLE)
213 return;
214
215 if (unlikely(size == 0))
216 return;
217
218 if (tty->driver->type == TTY_DRIVER_TYPE_PTY
219 && tty->driver->subtype == PTY_TYPE_MASTER)
220 return;
221
222 if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty))
223 return;
224
225 buf = tty_audit_buf_get();
226 if (IS_ERR_OR_NULL(buf))
227 return;
228
229 mutex_lock(&buf->mutex);
230 dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
231 if (buf->dev != dev || buf->icanon != icanon) {
232 tty_audit_buf_push(buf);
233 buf->dev = dev;
234 buf->icanon = icanon;
235 }
236 do {
237 size_t run;
238
239 run = N_TTY_BUF_SIZE - buf->valid;
240 if (run > size)
241 run = size;
242 memcpy(buf->data + buf->valid, data, run);
243 buf->valid += run;
244 data += run;
245 size -= run;
246 if (buf->valid == N_TTY_BUF_SIZE)
247 tty_audit_buf_push(buf);
248 } while (size != 0);
249 mutex_unlock(&buf->mutex);
250}