Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Andrew Lutomirski | 2524 | 99.29% | 7 | 63.64% |
Dominik Brodowski | 9 | 0.35% | 1 | 9.09% |
Shuah Khan | 7 | 0.28% | 1 | 9.09% |
Colin Ian King | 1 | 0.04% | 1 | 9.09% |
Sebastian Andrzej Siewior | 1 | 0.04% | 1 | 9.09% |
Total | 2542 | 11 |
/* SPDX-License-Identifier: GPL-2.0 */ #define _GNU_SOURCE #include <stdio.h> #include <sys/time.h> #include <time.h> #include <stdlib.h> #include <sys/syscall.h> #include <unistd.h> #include <dlfcn.h> #include <string.h> #include <inttypes.h> #include <signal.h> #include <sys/ucontext.h> #include <errno.h> #include <err.h> #include <sched.h> #include <stdbool.h> #include <setjmp.h> #include <sys/uio.h> #include "helpers.h" #ifdef __x86_64__ # define VSYS(x) (x) #else # define VSYS(x) 0 #endif #ifndef SYS_getcpu # ifdef __x86_64__ # define SYS_getcpu 309 # else # define SYS_getcpu 318 # endif #endif /* max length of lines in /proc/self/maps - anything longer is skipped here */ #define MAPS_LINE_LEN 128 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = handler; sa.sa_flags = SA_SIGINFO | flags; sigemptyset(&sa.sa_mask); if (sigaction(sig, &sa, 0)) err(1, "sigaction"); } /* vsyscalls and vDSO */ bool vsyscall_map_r = false, vsyscall_map_x = false; typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); const gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000); gtod_t vdso_gtod; typedef int (*vgettime_t)(clockid_t, struct timespec *); vgettime_t vdso_gettime; typedef long (*time_func_t)(time_t *t); const time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400); time_func_t vdso_time; typedef long (*getcpu_t)(unsigned *, unsigned *, void *); const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800); getcpu_t vdso_getcpu; static void init_vdso(void) { void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); if (!vdso) vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); if (!vdso) { printf("[WARN]\tfailed to find vDSO\n"); return; } vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday"); if (!vdso_gtod) printf("[WARN]\tfailed to find gettimeofday in vDSO\n"); vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime"); if (!vdso_gettime) printf("[WARN]\tfailed to find clock_gettime in vDSO\n"); vdso_time = (time_func_t)dlsym(vdso, "__vdso_time"); if (!vdso_time) printf("[WARN]\tfailed to find time in vDSO\n"); vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu"); if (!vdso_getcpu) printf("[WARN]\tfailed to find getcpu in vDSO\n"); } static int init_vsys(void) { #ifdef __x86_64__ int nerrs = 0; FILE *maps; char line[MAPS_LINE_LEN]; bool found = false; maps = fopen("/proc/self/maps", "r"); if (!maps) { printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n"); vsyscall_map_r = true; return 0; } while (fgets(line, MAPS_LINE_LEN, maps)) { char r, x; void *start, *end; char name[MAPS_LINE_LEN]; /* sscanf() is safe here as strlen(name) >= strlen(line) */ if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s", &start, &end, &r, &x, name) != 5) continue; if (strcmp(name, "[vsyscall]")) continue; printf("\tvsyscall map: %s", line); if (start != (void *)0xffffffffff600000 || end != (void *)0xffffffffff601000) { printf("[FAIL]\taddress range is nonsense\n"); nerrs++; } printf("\tvsyscall permissions are %c-%c\n", r, x); vsyscall_map_r = (r == 'r'); vsyscall_map_x = (x == 'x'); found = true; break; } fclose(maps); if (!found) { printf("\tno vsyscall map in /proc/self/maps\n"); vsyscall_map_r = false; vsyscall_map_x = false; } return nerrs; #else return 0; #endif } /* syscalls */ static inline long sys_gtod(struct timeval *tv, struct timezone *tz) { return syscall(SYS_gettimeofday, tv, tz); } static inline int sys_clock_gettime(clockid_t id, struct timespec *ts) { return syscall(SYS_clock_gettime, id, ts); } static inline long sys_time(time_t *t) { return syscall(SYS_time, t); } static inline long sys_getcpu(unsigned * cpu, unsigned * node, void* cache) { return syscall(SYS_getcpu, cpu, node, cache); } static jmp_buf jmpbuf; static volatile unsigned long segv_err; static void sigsegv(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t *)ctx_void; segv_err = ctx->uc_mcontext.gregs[REG_ERR]; siglongjmp(jmpbuf, 1); } static double tv_diff(const struct timeval *a, const struct timeval *b) { return (double)(a->tv_sec - b->tv_sec) + (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6; } static int check_gtod(const struct timeval *tv_sys1, const struct timeval *tv_sys2, const struct timezone *tz_sys, const char *which, const struct timeval *tv_other, const struct timezone *tz_other) { int nerrs = 0; double d1, d2; if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) { printf("[FAIL] %s tz mismatch\n", which); nerrs++; } d1 = tv_diff(tv_other, tv_sys1); d2 = tv_diff(tv_sys2, tv_other); printf("\t%s time offsets: %lf %lf\n", which, d1, d2); if (d1 < 0 || d2 < 0) { printf("[FAIL]\t%s time was inconsistent with the syscall\n", which); nerrs++; } else { printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which); } return nerrs; } static int test_gtod(void) { struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys; struct timezone tz_sys, tz_vdso, tz_vsys; long ret_vdso = -1; long ret_vsys = -1; int nerrs = 0; printf("[RUN]\ttest gettimeofday()\n"); if (sys_gtod(&tv_sys1, &tz_sys) != 0) err(1, "syscall gettimeofday"); if (vdso_gtod) ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso); if (vsyscall_map_x) ret_vsys = vgtod(&tv_vsys, &tz_vsys); if (sys_gtod(&tv_sys2, &tz_sys) != 0) err(1, "syscall gettimeofday"); if (vdso_gtod) { if (ret_vdso == 0) { nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso); } else { printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso); nerrs++; } } if (vsyscall_map_x) { if (ret_vsys == 0) { nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys); } else { printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys); nerrs++; } } return nerrs; } static int test_time(void) { int nerrs = 0; printf("[RUN]\ttest time()\n"); long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0; long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1; t_sys1 = sys_time(&t2_sys1); if (vdso_time) t_vdso = vdso_time(&t2_vdso); if (vsyscall_map_x) t_vsys = vtime(&t2_vsys); t_sys2 = sys_time(&t2_sys2); if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) { printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2); nerrs++; return nerrs; } if (vdso_time) { if (t_vdso < 0 || t_vdso != t2_vdso) { printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso); nerrs++; } else if (t_vdso < t_sys1 || t_vdso > t_sys2) { printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2); nerrs++; } else { printf("[OK]\tvDSO time() is okay\n"); } } if (vsyscall_map_x) { if (t_vsys < 0 || t_vsys != t2_vsys) { printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys); nerrs++; } else if (t_vsys < t_sys1 || t_vsys > t_sys2) { printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2); nerrs++; } else { printf("[OK]\tvsyscall time() is okay\n"); } } return nerrs; } static int test_getcpu(int cpu) { int nerrs = 0; long ret_sys, ret_vdso = -1, ret_vsys = -1; printf("[RUN]\tgetcpu() on CPU %d\n", cpu); cpu_set_t cpuset; CPU_ZERO(&cpuset); CPU_SET(cpu, &cpuset); if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) { printf("[SKIP]\tfailed to force CPU %d\n", cpu); return nerrs; } unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys; unsigned node = 0; bool have_node = false; ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0); if (vdso_getcpu) ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0); if (vsyscall_map_x) ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0); if (ret_sys == 0) { if (cpu_sys != cpu) { printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu); nerrs++; } have_node = true; node = node_sys; } if (vdso_getcpu) { if (ret_vdso) { printf("[FAIL]\tvDSO getcpu() failed\n"); nerrs++; } else { if (!have_node) { have_node = true; node = node_vdso; } if (cpu_vdso != cpu) { printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu); nerrs++; } else { printf("[OK]\tvDSO reported correct CPU\n"); } if (node_vdso != node) { printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node); nerrs++; } else { printf("[OK]\tvDSO reported correct node\n"); } } } if (vsyscall_map_x) { if (ret_vsys) { printf("[FAIL]\tvsyscall getcpu() failed\n"); nerrs++; } else { if (!have_node) { have_node = true; node = node_vsys; } if (cpu_vsys != cpu) { printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu); nerrs++; } else { printf("[OK]\tvsyscall reported correct CPU\n"); } if (node_vsys != node) { printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node); nerrs++; } else { printf("[OK]\tvsyscall reported correct node\n"); } } } return nerrs; } static int test_vsys_r(void) { #ifdef __x86_64__ printf("[RUN]\tChecking read access to the vsyscall page\n"); bool can_read; if (sigsetjmp(jmpbuf, 1) == 0) { *(volatile int *)0xffffffffff600000; can_read = true; } else { can_read = false; } if (can_read && !vsyscall_map_r) { printf("[FAIL]\tWe have read access, but we shouldn't\n"); return 1; } else if (!can_read && vsyscall_map_r) { printf("[FAIL]\tWe don't have read access, but we should\n"); return 1; } else if (can_read) { printf("[OK]\tWe have read access\n"); } else { printf("[OK]\tWe do not have read access: #PF(0x%lx)\n", segv_err); } #endif return 0; } static int test_vsys_x(void) { #ifdef __x86_64__ if (vsyscall_map_x) { /* We already tested this adequately. */ return 0; } printf("[RUN]\tMake sure that vsyscalls really page fault\n"); bool can_exec; if (sigsetjmp(jmpbuf, 1) == 0) { vgtod(NULL, NULL); can_exec = true; } else { can_exec = false; } if (can_exec) { printf("[FAIL]\tExecuting the vsyscall did not page fault\n"); return 1; } else if (segv_err & (1 << 4)) { /* INSTR */ printf("[OK]\tExecuting the vsyscall page failed: #PF(0x%lx)\n", segv_err); } else { printf("[FAIL]\tExecution failed with the wrong error: #PF(0x%lx)\n", segv_err); return 1; } #endif return 0; } /* * Debuggers expect ptrace() to be able to peek at the vsyscall page. * Use process_vm_readv() as a proxy for ptrace() to test this. We * want it to work in the vsyscall=emulate case and to fail in the * vsyscall=xonly case. * * It's worth noting that this ABI is a bit nutty. write(2) can't * read from the vsyscall page on any kernel version or mode. The * fact that ptrace() ever worked was a nice courtesy of old kernels, * but the code to support it is fairly gross. */ static int test_process_vm_readv(void) { #ifdef __x86_64__ char buf[4096]; struct iovec local, remote; int ret; printf("[RUN]\tprocess_vm_readv() from vsyscall page\n"); local.iov_base = buf; local.iov_len = 4096; remote.iov_base = (void *)0xffffffffff600000; remote.iov_len = 4096; ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0); if (ret != 4096) { /* * We expect process_vm_readv() to work if and only if the * vsyscall page is readable. */ printf("[%s]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", vsyscall_map_r ? "FAIL" : "OK", ret, errno); return vsyscall_map_r ? 1 : 0; } if (vsyscall_map_r) { if (!memcmp(buf, remote.iov_base, sizeof(buf))) { printf("[OK]\tIt worked and read correct data\n"); } else { printf("[FAIL]\tIt worked but returned incorrect data\n"); return 1; } } else { printf("[FAIL]\tprocess_rm_readv() succeeded, but it should have failed in this configuration\n"); return 1; } #endif return 0; } #ifdef __x86_64__ static volatile sig_atomic_t num_vsyscall_traps; static void sigtrap(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t *)ctx_void; unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP]; if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0) num_vsyscall_traps++; } static int test_emulation(void) { time_t tmp; bool is_native; if (!vsyscall_map_x) return 0; printf("[RUN]\tchecking that vsyscalls are emulated\n"); sethandler(SIGTRAP, sigtrap, 0); set_eflags(get_eflags() | X86_EFLAGS_TF); vtime(&tmp); set_eflags(get_eflags() & ~X86_EFLAGS_TF); /* * If vsyscalls are emulated, we expect a single trap in the * vsyscall page -- the call instruction will trap with RIP * pointing to the entry point before emulation takes over. * In native mode, we expect two traps, since whatever code * the vsyscall page contains will be more than just a ret * instruction. */ is_native = (num_vsyscall_traps > 1); printf("[%s]\tvsyscalls are %s (%d instructions in vsyscall page)\n", (is_native ? "FAIL" : "OK"), (is_native ? "native" : "emulated"), (int)num_vsyscall_traps); return is_native; } #endif int main(int argc, char **argv) { int nerrs = 0; init_vdso(); nerrs += init_vsys(); nerrs += test_gtod(); nerrs += test_time(); nerrs += test_getcpu(0); nerrs += test_getcpu(1); sethandler(SIGSEGV, sigsegv, 0); nerrs += test_vsys_r(); nerrs += test_vsys_x(); nerrs += test_process_vm_readv(); #ifdef __x86_64__ nerrs += test_emulation(); #endif return nerrs ? 1 : 0; }
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