1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | |
3 | #define _GNU_SOURCE |
4 | #include <signal.h> |
5 | #include <stdio.h> |
6 | #include <stdbool.h> |
7 | #include <string.h> |
8 | #include <err.h> |
9 | #include <errno.h> |
10 | #include <limits.h> |
11 | #include <sys/mman.h> |
12 | #include <sys/auxv.h> |
13 | #include <sys/prctl.h> |
14 | #include <sys/resource.h> |
15 | #include <setjmp.h> |
16 | |
17 | /* sigaltstack()-enforced minimum stack */ |
18 | #define ENFORCED_MINSIGSTKSZ 2048 |
19 | |
20 | #ifndef AT_MINSIGSTKSZ |
21 | # define AT_MINSIGSTKSZ 51 |
22 | #endif |
23 | |
24 | static int nerrs; |
25 | |
26 | static bool sigalrm_expected; |
27 | |
28 | static unsigned long at_minstack_size; |
29 | |
30 | static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), |
31 | int flags) |
32 | { |
33 | struct sigaction sa; |
34 | |
35 | memset(&sa, 0, sizeof(sa)); |
36 | sa.sa_sigaction = handler; |
37 | sa.sa_flags = SA_SIGINFO | flags; |
38 | sigemptyset(&sa.sa_mask); |
39 | if (sigaction(sig, &sa, 0)) |
40 | err(1, "sigaction" ); |
41 | } |
42 | |
43 | static void clearhandler(int sig) |
44 | { |
45 | struct sigaction sa; |
46 | |
47 | memset(&sa, 0, sizeof(sa)); |
48 | sa.sa_handler = SIG_DFL; |
49 | sigemptyset(&sa.sa_mask); |
50 | if (sigaction(sig, &sa, 0)) |
51 | err(1, "sigaction" ); |
52 | } |
53 | |
54 | static int setup_altstack(void *start, unsigned long size) |
55 | { |
56 | stack_t ss; |
57 | |
58 | memset(&ss, 0, sizeof(ss)); |
59 | ss.ss_size = size; |
60 | ss.ss_sp = start; |
61 | |
62 | return sigaltstack(&ss, NULL); |
63 | } |
64 | |
65 | static jmp_buf jmpbuf; |
66 | |
67 | static void sigsegv(int sig, siginfo_t *info, void *ctx_void) |
68 | { |
69 | if (sigalrm_expected) { |
70 | printf("[FAIL]\tWrong signal delivered: SIGSEGV (expected SIGALRM)." ); |
71 | nerrs++; |
72 | } else { |
73 | printf("[OK]\tSIGSEGV signal delivered.\n" ); |
74 | } |
75 | |
76 | siglongjmp(jmpbuf, 1); |
77 | } |
78 | |
79 | static void sigalrm(int sig, siginfo_t *info, void *ctx_void) |
80 | { |
81 | if (!sigalrm_expected) { |
82 | printf("[FAIL]\tWrong signal delivered: SIGALRM (expected SIGSEGV)." ); |
83 | nerrs++; |
84 | } else { |
85 | printf("[OK]\tSIGALRM signal delivered.\n" ); |
86 | } |
87 | } |
88 | |
89 | static void test_sigaltstack(void *altstack, unsigned long size) |
90 | { |
91 | if (setup_altstack(start: altstack, size)) |
92 | err(1, "sigaltstack()" ); |
93 | |
94 | sigalrm_expected = (size > at_minstack_size) ? true : false; |
95 | |
96 | sethandler(sig: SIGSEGV, handler: sigsegv, flags: 0); |
97 | sethandler(sig: SIGALRM, handler: sigalrm, flags: SA_ONSTACK); |
98 | |
99 | if (!sigsetjmp(jmpbuf, 1)) { |
100 | printf("[RUN]\tTest an alternate signal stack of %ssufficient size.\n" , |
101 | sigalrm_expected ? "" : "in" ); |
102 | printf("\tRaise SIGALRM. %s is expected to be delivered.\n" , |
103 | sigalrm_expected ? "It" : "SIGSEGV" ); |
104 | raise(SIGALRM); |
105 | } |
106 | |
107 | clearhandler(sig: SIGALRM); |
108 | clearhandler(sig: SIGSEGV); |
109 | } |
110 | |
111 | int main(void) |
112 | { |
113 | void *altstack; |
114 | |
115 | at_minstack_size = getauxval(AT_MINSIGSTKSZ); |
116 | |
117 | altstack = mmap(NULL, at_minstack_size + SIGSTKSZ, PROT_READ | PROT_WRITE, |
118 | MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); |
119 | if (altstack == MAP_FAILED) |
120 | err(1, "mmap()" ); |
121 | |
122 | if ((ENFORCED_MINSIGSTKSZ + 1) < at_minstack_size) |
123 | test_sigaltstack(altstack, ENFORCED_MINSIGSTKSZ + 1); |
124 | |
125 | test_sigaltstack(altstack, size: at_minstack_size + SIGSTKSZ); |
126 | |
127 | return nerrs == 0 ? 0 : 1; |
128 | } |
129 | |