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