summaryrefslogtreecommitdiff
path: root/libc/sysdeps/linux/common/ssp.c
blob: b939b4ea07929d1fa89588fe4c94b4df1be1fb22 (plain)
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
/*
 * Distributed under the terms of the GNU Lesser General Public License
 * $Header: $
 *
 * This is a modified version of Hiroaki Etoh's stack smashing routines
 * implemented for glibc.
 *
 * The following people have contributed input to this code.
 * Ned Ludd - <solar[@]gentoo.org>
 * Alexander Gabert - <pappy[@]gentoo.org>
 * The PaX Team - <pageexec[@]freemail.hu>
 * Peter S. Mazinger - <ps.m[@]gmx.net>
 * Yoann Vandoorselaere - <yoann[@]prelude-ids.org>
 * Robert Connolly - <robert[@]linuxfromscratch.org>
 * Cory Visi <cory[@]visi.name>
 * Mike Frysinger <vapier[@]gentoo.org>
 */

#if defined __SSP__ || defined __SSP_ALL__
#error "file must not be compiled with stack protection enabled on it. Use -fno-stack-protector"
#endif

#ifdef __PROPOLICE_BLOCK_SEGV__
# define SSP_SIGTYPE SIGSEGV
#else
# define SSP_SIGTYPE SIGABRT
#endif

#include <string.h>
#include <unistd.h>
#include <signal.h>
#if defined __UCLIBC_HAS_SYSLOG__
#include <sys/syslog.h>

libc_hidden_proto(openlog)
libc_hidden_proto(syslog)
libc_hidden_proto(closelog)
#endif

/* libc_hidden_proto(sigaction) */
libc_hidden_proto(sigfillset)
libc_hidden_proto(sigdelset)
/* libc_hidden_proto(sigprocmask) */
/* libc_hidden_proto(write) */
libc_hidden_proto(kill)
/* libc_hidden_proto(getpid) */
/* libc_hidden_proto(_exit) */

static void block_signals(void)
{
	struct sigaction sa;
	sigset_t mask;

	sigfillset(&mask);

	sigdelset(&mask, SSP_SIGTYPE);	/* Block all signal handlers */
	sigprocmask(SIG_BLOCK, &mask, NULL);	/* except SSP_SIGTYPE */

	/* Make the default handler associated with the signal handler */
	memset(&sa, 0, sizeof(struct sigaction));
	sigfillset(&sa.sa_mask);	/* Block all signals */
	sa.sa_flags = 0;
	sa.sa_handler = SIG_DFL;
	sigaction(SSP_SIGTYPE, &sa, NULL);
}

static void ssp_write(int fd, const char *msg1, const char *msg2, const char *msg3) __cold
{
	write(fd, msg1, strlen(msg1));
	write(fd, msg2, strlen(msg2));
	write(fd, msg3, strlen(msg3));
	write(fd, "()\n", 3);
#if defined __UCLIBC_HAS_SYSLOG__
	openlog("ssp", LOG_CONS | LOG_PID, LOG_USER);
	syslog(LOG_INFO, "%s%s%s()", msg1, msg2, msg3);
	closelog();
#endif
}

static attribute_noreturn void terminate(void)
{
	(void) kill(getpid(), SSP_SIGTYPE);
	_exit(127);
}

void __stack_smash_handler(char func[], int damaged __attribute__ ((unused))) attribute_noreturn __cold;
void __stack_smash_handler(char func[], int damaged)
{
	static const char message[] = ": stack smashing attack in function ";

	block_signals();

	ssp_write(STDERR_FILENO, __uclibc_progname, message, func);

	/* The loop is added only to keep gcc happy. */
	while(1)
		terminate();
}

void __stack_chk_fail(void) attribute_noreturn __cold;
void __stack_chk_fail(void)
{
	static const char msg1[] = "stack smashing detected: ";
	static const char msg3[] = " terminated";

	block_signals();

	ssp_write(STDERR_FILENO, msg1, __uclibc_progname, msg3);

	/* The loop is added only to keep gcc happy. */
	while(1)
		terminate();
}

#if 0
void __chk_fail(void) attribute_noreturn;
void __chk_fail(void)
{
	static const char msg1[] = "buffer overflow detected: ";
	static const char msg3[] = " terminated";

	block_signals();

	ssp_write(STDERR_FILENO, msg1, __uclibc_progname, msg3);

	/* The loop is added only to keep gcc happy. */
	while(1)
		terminate();
}
#endif