Loading...
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 | // SPDX-License-Identifier: GPL-2.0 /* * Stas Sergeev <stsp@users.sourceforge.net> * * test sigaltstack(SS_ONSTACK | SS_AUTODISARM) * If that succeeds, then swapcontext() can be used inside sighandler safely. * */ #define _GNU_SOURCE #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <ucontext.h> #include <alloca.h> #include <string.h> #include <assert.h> #include <errno.h> #include <sys/auxv.h> #include "../kselftest.h" #include "current_stack_pointer.h" #ifndef SS_AUTODISARM #define SS_AUTODISARM (1U << 31) #endif #ifndef AT_MINSIGSTKSZ #define AT_MINSIGSTKSZ 51 #endif static unsigned int stack_size; static void *sstack, *ustack; static ucontext_t uc, sc; static const char *msg = "[OK]\tStack preserved"; static const char *msg2 = "[FAIL]\tStack corrupted"; struct stk_data { char msg[128]; int flag; }; void my_usr1(int sig, siginfo_t *si, void *u) { char *aa; int err; stack_t stk; struct stk_data *p; if (sp < (unsigned long)sstack || sp >= (unsigned long)sstack + stack_size) { ksft_exit_fail_msg("SP is not on sigaltstack\n"); } /* put some data on stack. other sighandler will try to overwrite it */ aa = alloca(1024); assert(aa); p = (struct stk_data *)(aa + 512); strcpy(p->msg, msg); p->flag = 1; ksft_print_msg("[RUN]\tsignal USR1\n"); err = sigaltstack(NULL, &stk); if (err) { ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno)); exit(EXIT_FAILURE); } if (stk.ss_flags != SS_DISABLE) ksft_test_result_fail("tss_flags=%x, should be SS_DISABLE\n", stk.ss_flags); else ksft_test_result_pass( "sigaltstack is disabled in sighandler\n"); swapcontext(&sc, &uc); ksft_print_msg("%s\n", p->msg); if (!p->flag) { ksft_exit_fail_msg("[RUN]\tAborting\n"); exit(EXIT_FAILURE); } } void my_usr2(int sig, siginfo_t *si, void *u) { char *aa; struct stk_data *p; ksft_print_msg("[RUN]\tsignal USR2\n"); aa = alloca(1024); /* dont run valgrind on this */ /* try to find the data stored by previous sighandler */ p = memmem(aa, 1024, msg, strlen(msg)); if (p) { ksft_test_result_fail("sigaltstack re-used\n"); /* corrupt the data */ strcpy(p->msg, msg2); /* tell other sighandler that his data is corrupted */ p->flag = 0; } } static void switch_fn(void) { ksft_print_msg("[RUN]\tswitched to user ctx\n"); raise(SIGUSR2); setcontext(&sc); } int main(void) { struct sigaction act; stack_t stk; int err; /* Make sure more than the required minimum. */ stack_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ; ksft_print_msg("[NOTE]\tthe stack size is %lu\n", stack_size); ksft_print_header(); ksft_set_plan(3); sigemptyset(&act.sa_mask); act.sa_flags = SA_ONSTACK | SA_SIGINFO; act.sa_sigaction = my_usr1; sigaction(SIGUSR1, &act, NULL); act.sa_sigaction = my_usr2; sigaction(SIGUSR2, &act, NULL); sstack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); if (sstack == MAP_FAILED) { ksft_exit_fail_msg("mmap() - %s\n", strerror(errno)); return EXIT_FAILURE; } err = sigaltstack(NULL, &stk); if (err) { ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno)); exit(EXIT_FAILURE); } if (stk.ss_flags == SS_DISABLE) { ksft_test_result_pass( "Initial sigaltstack state was SS_DISABLE\n"); } else { ksft_exit_fail_msg("Initial sigaltstack state was %x; " "should have been SS_DISABLE\n", stk.ss_flags); return EXIT_FAILURE; } stk.ss_sp = sstack; stk.ss_size = stack_size; stk.ss_flags = SS_ONSTACK | SS_AUTODISARM; err = sigaltstack(&stk, NULL); if (err) { if (errno == EINVAL) { ksft_test_result_skip( "[NOTE]\tThe running kernel doesn't support SS_AUTODISARM\n"); /* * If test cases for the !SS_AUTODISARM variant were * added, we could still run them. We don't have any * test cases like that yet, so just exit and report * success. */ return 0; } else { ksft_exit_fail_msg( "sigaltstack(SS_ONSTACK | SS_AUTODISARM) %s\n", strerror(errno)); return EXIT_FAILURE; } } ustack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); if (ustack == MAP_FAILED) { ksft_exit_fail_msg("mmap() - %s\n", strerror(errno)); return EXIT_FAILURE; } getcontext(&uc); uc.uc_link = NULL; uc.uc_stack.ss_sp = ustack; uc.uc_stack.ss_size = stack_size; makecontext(&uc, switch_fn, 0); raise(SIGUSR1); err = sigaltstack(NULL, &stk); if (err) { ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno)); exit(EXIT_FAILURE); } if (stk.ss_flags != SS_AUTODISARM) { ksft_exit_fail_msg("ss_flags=%x, should be SS_AUTODISARM\n", stk.ss_flags); exit(EXIT_FAILURE); } ksft_test_result_pass( "sigaltstack is still SS_AUTODISARM after signal\n"); ksft_exit_pass(); return 0; } |