1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2009-2016 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include "sudo.h"
#include "sudo_exec.h"
static struct signal_state {
int signo;
int restore;
struct sigaction sa;
} saved_signals[] = {
{ SIGALRM }, /* SAVED_SIGALRM */
{ SIGCHLD }, /* SAVED_SIGCHLD */
{ SIGCONT }, /* SAVED_SIGCONT */
{ SIGHUP }, /* SAVED_SIGHUP */
{ SIGINT }, /* SAVED_SIGINT */
{ SIGPIPE }, /* SAVED_SIGPIPE */
{ SIGQUIT }, /* SAVED_SIGQUIT */
{ SIGTERM }, /* SAVED_SIGTERM */
{ SIGTSTP }, /* SAVED_SIGTSTP */
{ SIGTTIN }, /* SAVED_SIGTTIN */
{ SIGTTOU }, /* SAVED_SIGTTOU */
{ SIGUSR1 }, /* SAVED_SIGUSR1 */
{ SIGUSR2 }, /* SAVED_SIGUSR2 */
{ -1 }
};
static sig_atomic_t pending_signals[NSIG];
static void
sudo_handler(int signo)
{
/* Mark signal as pending. */
pending_signals[signo] = 1;
}
bool
signal_pending(int signo)
{
return pending_signals[signo] == 1;
}
/*
* Save signal handler state so it can be restored before exec.
*/
void
save_signals(void)
{
struct signal_state *ss;
debug_decl(save_signals, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo != -1; ss++) {
if (sigaction(ss->signo, NULL, &ss->sa) != 0)
sudo_warn(U_("unable to save handler for signal %d"), ss->signo);
}
debug_return;
}
/*
* Restore signal handlers to initial state for exec.
*/
void
restore_signals(void)
{
struct signal_state *ss;
debug_decl(restore_signals, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo != -1; ss++) {
if (ss->restore) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"restoring handler for signal %d: %s", ss->signo,
ss->sa.sa_handler == SIG_IGN ? "SIG_IGN" :
ss->sa.sa_handler == SIG_DFL ? "SIG_DFL" : "???");
if (sigaction(ss->signo, &ss->sa, NULL) != 0) {
sudo_warn(U_("unable to restore handler for signal %d"),
ss->signo);
}
}
}
debug_return;
}
/*
* Trap tty-generated (and other) signals so we can't be killed before
* calling the policy close function. The signal pipe will be drained
* in sudo_execute() before running the command and new handlers will
* be installed in the parent.
*/
void
init_signals(void)
{
struct sigaction sa;
struct signal_state *ss;
debug_decl(init_signals, SUDO_DEBUG_MAIN);
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = sudo_handler;
for (ss = saved_signals; ss->signo > 0; ss++) {
switch (ss->signo) {
case SIGCONT:
case SIGPIPE:
case SIGTTIN:
case SIGTTOU:
/* Don't install these until exec time. */
break;
default:
if (ss->sa.sa_handler != SIG_IGN) {
if (sigaction(ss->signo, &sa, NULL) != 0) {
sudo_warn(U_("unable to set handler for signal %d"),
ss->signo);
}
}
break;
}
}
/* Ignore SIGPIPE until exec. */
if (saved_signals[SAVED_SIGPIPE].sa.sa_handler != SIG_IGN) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"will restore signal %d on exec", SIGPIPE);
saved_signals[SAVED_SIGPIPE].restore = true;
sa.sa_handler = SIG_IGN;
if (sigaction(SIGPIPE, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGPIPE);
}
debug_return;
}
/*
* Like sigaction() but sets restore flag in saved_signals[]
* if needed.
*/
int
sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa)
{
struct signal_state *ss;
int ret;
debug_decl(sudo_sigaction, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo > 0; ss++) {
if (ss->signo == signo) {
/* If signal was or now is ignored, restore old handler on exec. */
if (ss->sa.sa_handler == SIG_IGN || sa->sa_handler == SIG_IGN) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"will restore signal %d on exec", signo);
ss->restore = true;
}
break;
}
}
ret = sigaction(signo, sa, osa);
debug_return_int(ret);
}
|
