1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 #define _GNU_SOURCE 4 5 #include <stdio.h> 6 #include <sys/time.h> 7 #include <time.h> 8 #include <stdlib.h> 9 #include <sys/syscall.h> 10 #include <unistd.h> 11 #include <dlfcn.h> 12 #include <string.h> 13 #include <inttypes.h> 14 #include <signal.h> 15 #include <sys/ucontext.h> 16 #include <errno.h> 17 #include <err.h> 18 #include <sched.h> 19 #include <stdbool.h> 20 #include <setjmp.h> 21 #include <sys/uio.h> 22 23 #include "helpers.h" 24 #include "../kselftest.h" 25 26 #ifdef __x86_64__ 27 #define TOTAL_TESTS 13 28 #else 29 #define TOTAL_TESTS 8 30 #endif 31 32 #ifdef __x86_64__ 33 # define VSYS(x) (x) 34 #else 35 # define VSYS(x) 0 36 #endif 37 38 #ifndef SYS_getcpu 39 # ifdef __x86_64__ 40 # define SYS_getcpu 309 41 # else 42 # define SYS_getcpu 318 43 # endif 44 #endif 45 46 /* max length of lines in /proc/self/maps - anything longer is skipped here */ 47 #define MAPS_LINE_LEN 128 48 49 /* vsyscalls and vDSO */ 50 bool vsyscall_map_r = false, vsyscall_map_x = false; 51 52 typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); 53 const gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000); 54 gtod_t vdso_gtod; 55 56 typedef int (*vgettime_t)(clockid_t, struct timespec *); 57 vgettime_t vdso_gettime; 58 59 typedef long (*time_func_t)(time_t *t); 60 const time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400); 61 time_func_t vdso_time; 62 63 typedef long (*getcpu_t)(unsigned *, unsigned *, void *); 64 const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800); 65 getcpu_t vdso_getcpu; 66 init_vdso(void)67 static void init_vdso(void) 68 { 69 void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); 70 if (!vdso) 71 vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); 72 if (!vdso) { 73 ksft_print_msg("[WARN] failed to find vDSO\n"); 74 return; 75 } 76 77 vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday"); 78 if (!vdso_gtod) 79 ksft_print_msg("[WARN] failed to find gettimeofday in vDSO\n"); 80 81 vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime"); 82 if (!vdso_gettime) 83 ksft_print_msg("[WARN] failed to find clock_gettime in vDSO\n"); 84 85 vdso_time = (time_func_t)dlsym(vdso, "__vdso_time"); 86 if (!vdso_time) 87 ksft_print_msg("[WARN] failed to find time in vDSO\n"); 88 89 vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu"); 90 if (!vdso_getcpu) 91 ksft_print_msg("[WARN] failed to find getcpu in vDSO\n"); 92 } 93 94 /* syscalls */ sys_gtod(struct timeval * tv,struct timezone * tz)95 static inline long sys_gtod(struct timeval *tv, struct timezone *tz) 96 { 97 return syscall(SYS_gettimeofday, tv, tz); 98 } 99 sys_time(time_t * t)100 static inline long sys_time(time_t *t) 101 { 102 return syscall(SYS_time, t); 103 } 104 sys_getcpu(unsigned * cpu,unsigned * node,void * cache)105 static inline long sys_getcpu(unsigned * cpu, unsigned * node, 106 void* cache) 107 { 108 return syscall(SYS_getcpu, cpu, node, cache); 109 } 110 tv_diff(const struct timeval * a,const struct timeval * b)111 static double tv_diff(const struct timeval *a, const struct timeval *b) 112 { 113 return (double)(a->tv_sec - b->tv_sec) + 114 (double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6; 115 } 116 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)117 static void check_gtod(const struct timeval *tv_sys1, 118 const struct timeval *tv_sys2, 119 const struct timezone *tz_sys, 120 const char *which, 121 const struct timeval *tv_other, 122 const struct timezone *tz_other) 123 { 124 double d1, d2; 125 126 if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || 127 tz_sys->tz_dsttime != tz_other->tz_dsttime)) 128 ksft_print_msg("%s tz mismatch\n", which); 129 130 d1 = tv_diff(tv_other, tv_sys1); 131 d2 = tv_diff(tv_sys2, tv_other); 132 133 ksft_print_msg("%s time offsets: %lf %lf\n", which, d1, d2); 134 135 ksft_test_result(!(d1 < 0 || d2 < 0), "%s gettimeofday()'s timeval\n", which); 136 } 137 test_gtod(void)138 static void test_gtod(void) 139 { 140 struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys; 141 struct timezone tz_sys, tz_vdso, tz_vsys; 142 long ret_vdso = -1; 143 long ret_vsys = -1; 144 145 ksft_print_msg("test gettimeofday()\n"); 146 147 if (sys_gtod(&tv_sys1, &tz_sys) != 0) 148 ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno)); 149 if (vdso_gtod) 150 ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso); 151 if (vsyscall_map_x) 152 ret_vsys = vgtod(&tv_vsys, &tz_vsys); 153 if (sys_gtod(&tv_sys2, &tz_sys) != 0) 154 ksft_exit_fail_msg("syscall gettimeofday: %s\n", strerror(errno)); 155 156 if (vdso_gtod) { 157 if (ret_vdso == 0) 158 check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso); 159 else 160 ksft_test_result_fail("vDSO gettimeofday() failed: %ld\n", ret_vdso); 161 } else { 162 ksft_test_result_skip("vdso_gtod isn't set\n"); 163 } 164 165 if (vsyscall_map_x) { 166 if (ret_vsys == 0) 167 check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys); 168 else 169 ksft_test_result_fail("vsys gettimeofday() failed: %ld\n", ret_vsys); 170 } else { 171 ksft_test_result_skip("vsyscall_map_x isn't set\n"); 172 } 173 } 174 test_time(void)175 static void test_time(void) 176 { 177 long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0; 178 long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1; 179 180 ksft_print_msg("test time()\n"); 181 t_sys1 = sys_time(&t2_sys1); 182 if (vdso_time) 183 t_vdso = vdso_time(&t2_vdso); 184 if (vsyscall_map_x) 185 t_vsys = vtime(&t2_vsys); 186 t_sys2 = sys_time(&t2_sys2); 187 if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) { 188 ksft_print_msg("syscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", 189 t_sys1, t2_sys1, t_sys2, t2_sys2); 190 ksft_test_result_skip("vdso_time\n"); 191 ksft_test_result_skip("vdso_time\n"); 192 return; 193 } 194 195 if (vdso_time) { 196 if (t_vdso < 0 || t_vdso != t2_vdso) 197 ksft_test_result_fail("vDSO failed (ret:%ld output:%ld)\n", 198 t_vdso, t2_vdso); 199 else if (t_vdso < t_sys1 || t_vdso > t_sys2) 200 ksft_test_result_fail("vDSO returned the wrong time (%ld %ld %ld)\n", 201 t_sys1, t_vdso, t_sys2); 202 else 203 ksft_test_result_pass("vDSO time() is okay\n"); 204 } else { 205 ksft_test_result_skip("vdso_time isn't set\n"); 206 } 207 208 if (vsyscall_map_x) { 209 if (t_vsys < 0 || t_vsys != t2_vsys) 210 ksft_test_result_fail("vsyscall failed (ret:%ld output:%ld)\n", 211 t_vsys, t2_vsys); 212 else if (t_vsys < t_sys1 || t_vsys > t_sys2) 213 ksft_test_result_fail("vsyscall returned the wrong time (%ld %ld %ld)\n", 214 t_sys1, t_vsys, t_sys2); 215 else 216 ksft_test_result_pass("vsyscall time() is okay\n"); 217 } else { 218 ksft_test_result_skip("vsyscall_map_x isn't set\n"); 219 } 220 } 221 test_getcpu(int cpu)222 static void test_getcpu(int cpu) 223 { 224 unsigned int cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys; 225 long ret_sys, ret_vdso = -1, ret_vsys = -1; 226 unsigned int node = 0; 227 bool have_node = false; 228 cpu_set_t cpuset; 229 230 ksft_print_msg("getcpu() on CPU %d\n", cpu); 231 232 CPU_ZERO(&cpuset); 233 CPU_SET(cpu, &cpuset); 234 if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) { 235 ksft_print_msg("failed to force CPU %d\n", cpu); 236 ksft_test_result_skip("vdso_getcpu\n"); 237 ksft_test_result_skip("vsyscall_map_x\n"); 238 239 return; 240 } 241 242 ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0); 243 if (vdso_getcpu) 244 ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0); 245 if (vsyscall_map_x) 246 ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0); 247 248 if (ret_sys == 0) { 249 if (cpu_sys != cpu) 250 ksft_print_msg("syscall reported CPU %u but should be %d\n", 251 cpu_sys, cpu); 252 253 have_node = true; 254 node = node_sys; 255 } 256 257 if (vdso_getcpu) { 258 if (ret_vdso) { 259 ksft_test_result_fail("vDSO getcpu() failed\n"); 260 } else { 261 if (!have_node) { 262 have_node = true; 263 node = node_vdso; 264 } 265 266 if (cpu_vdso != cpu || node_vdso != node) { 267 if (cpu_vdso != cpu) 268 ksft_print_msg("vDSO reported CPU %u but should be %d\n", 269 cpu_vdso, cpu); 270 if (node_vdso != node) 271 ksft_print_msg("vDSO reported node %u but should be %u\n", 272 node_vdso, node); 273 ksft_test_result_fail("Wrong values\n"); 274 } else { 275 ksft_test_result_pass("vDSO reported correct CPU and node\n"); 276 } 277 } 278 } else { 279 ksft_test_result_skip("vdso_getcpu isn't set\n"); 280 } 281 282 if (vsyscall_map_x) { 283 if (ret_vsys) { 284 ksft_test_result_fail("vsyscall getcpu() failed\n"); 285 } else { 286 if (!have_node) { 287 have_node = true; 288 node = node_vsys; 289 } 290 291 if (cpu_vsys != cpu || node_vsys != node) { 292 if (cpu_vsys != cpu) 293 ksft_print_msg("vsyscall reported CPU %u but should be %d\n", 294 cpu_vsys, cpu); 295 if (node_vsys != node) 296 ksft_print_msg("vsyscall reported node %u but should be %u\n", 297 node_vsys, node); 298 ksft_test_result_fail("Wrong values\n"); 299 } else { 300 ksft_test_result_pass("vsyscall reported correct CPU and node\n"); 301 } 302 } 303 } else { 304 ksft_test_result_skip("vsyscall_map_x isn't set\n"); 305 } 306 } 307 308 #ifdef __x86_64__ 309 310 static jmp_buf jmpbuf; 311 static volatile unsigned long segv_err; 312 sethandler(int sig,void (* handler)(int,siginfo_t *,void *),int flags)313 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), 314 int flags) 315 { 316 struct sigaction sa; 317 318 memset(&sa, 0, sizeof(sa)); 319 sa.sa_sigaction = handler; 320 sa.sa_flags = SA_SIGINFO | flags; 321 sigemptyset(&sa.sa_mask); 322 if (sigaction(sig, &sa, 0)) 323 ksft_exit_fail_msg("sigaction failed\n"); 324 } 325 sigsegv(int sig,siginfo_t * info,void * ctx_void)326 static void sigsegv(int sig, siginfo_t *info, void *ctx_void) 327 { 328 ucontext_t *ctx = (ucontext_t *)ctx_void; 329 330 segv_err = ctx->uc_mcontext.gregs[REG_ERR]; 331 siglongjmp(jmpbuf, 1); 332 } 333 test_vsys_r(void)334 static void test_vsys_r(void) 335 { 336 ksft_print_msg("Checking read access to the vsyscall page\n"); 337 bool can_read; 338 if (sigsetjmp(jmpbuf, 1) == 0) { 339 *(volatile int *)0xffffffffff600000; 340 can_read = true; 341 } else { 342 can_read = false; 343 } 344 345 if (can_read && !vsyscall_map_r) 346 ksft_test_result_fail("We have read access, but we shouldn't\n"); 347 else if (!can_read && vsyscall_map_r) 348 ksft_test_result_fail("We don't have read access, but we should\n"); 349 else if (can_read) 350 ksft_test_result_pass("We have read access\n"); 351 else 352 ksft_test_result_pass("We do not have read access: #PF(0x%lx)\n", segv_err); 353 } 354 test_vsys_x(void)355 static void test_vsys_x(void) 356 { 357 if (vsyscall_map_x) { 358 /* We already tested this adequately. */ 359 ksft_test_result_pass("vsyscall_map_x is true\n"); 360 return; 361 } 362 363 ksft_print_msg("Make sure that vsyscalls really page fault\n"); 364 365 bool can_exec; 366 if (sigsetjmp(jmpbuf, 1) == 0) { 367 vgtod(NULL, NULL); 368 can_exec = true; 369 } else { 370 can_exec = false; 371 } 372 373 if (can_exec) 374 ksft_test_result_fail("Executing the vsyscall did not page fault\n"); 375 else if (segv_err & (1 << 4)) /* INSTR */ 376 ksft_test_result_pass("Executing the vsyscall page failed: #PF(0x%lx)\n", 377 segv_err); 378 else 379 ksft_test_result_fail("Execution failed with the wrong error: #PF(0x%lx)\n", 380 segv_err); 381 } 382 383 /* 384 * Debuggers expect ptrace() to be able to peek at the vsyscall page. 385 * Use process_vm_readv() as a proxy for ptrace() to test this. We 386 * want it to work in the vsyscall=emulate case and to fail in the 387 * vsyscall=xonly case. 388 * 389 * It's worth noting that this ABI is a bit nutty. write(2) can't 390 * read from the vsyscall page on any kernel version or mode. The 391 * fact that ptrace() ever worked was a nice courtesy of old kernels, 392 * but the code to support it is fairly gross. 393 */ test_process_vm_readv(void)394 static void test_process_vm_readv(void) 395 { 396 char buf[4096]; 397 struct iovec local, remote; 398 int ret; 399 400 ksft_print_msg("process_vm_readv() from vsyscall page\n"); 401 402 local.iov_base = buf; 403 local.iov_len = 4096; 404 remote.iov_base = (void *)0xffffffffff600000; 405 remote.iov_len = 4096; 406 ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0); 407 if (ret != 4096) { 408 /* 409 * We expect process_vm_readv() to work if and only if the 410 * vsyscall page is readable. 411 */ 412 ksft_test_result(!vsyscall_map_r, 413 "process_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno); 414 return; 415 } 416 417 if (vsyscall_map_r) 418 ksft_test_result(!memcmp(buf, remote.iov_base, sizeof(buf)), "Read data\n"); 419 else 420 ksft_test_result_fail("process_rm_readv() succeeded, but it should have failed in this configuration\n"); 421 } 422 init_vsys(void)423 static void init_vsys(void) 424 { 425 int nerrs = 0; 426 FILE *maps; 427 char line[MAPS_LINE_LEN]; 428 bool found = false; 429 430 maps = fopen("/proc/self/maps", "r"); 431 if (!maps) { 432 ksft_test_result_skip("Could not open /proc/self/maps -- assuming vsyscall is r-x\n"); 433 vsyscall_map_r = true; 434 return; 435 } 436 437 while (fgets(line, MAPS_LINE_LEN, maps)) { 438 char r, x; 439 void *start, *end; 440 char name[MAPS_LINE_LEN]; 441 442 /* sscanf() is safe here as strlen(name) >= strlen(line) */ 443 if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s", 444 &start, &end, &r, &x, name) != 5) 445 continue; 446 447 if (strcmp(name, "[vsyscall]")) 448 continue; 449 450 ksft_print_msg("vsyscall map: %s", line); 451 452 if (start != (void *)0xffffffffff600000 || 453 end != (void *)0xffffffffff601000) { 454 ksft_print_msg("address range is nonsense\n"); 455 nerrs++; 456 } 457 458 ksft_print_msg("vsyscall permissions are %c-%c\n", r, x); 459 vsyscall_map_r = (r == 'r'); 460 vsyscall_map_x = (x == 'x'); 461 462 found = true; 463 break; 464 } 465 466 fclose(maps); 467 468 if (!found) { 469 ksft_print_msg("no vsyscall map in /proc/self/maps\n"); 470 vsyscall_map_r = false; 471 vsyscall_map_x = false; 472 } 473 474 ksft_test_result(!nerrs, "vsyscall map\n"); 475 } 476 477 static volatile sig_atomic_t num_vsyscall_traps; 478 sigtrap(int sig,siginfo_t * info,void * ctx_void)479 static void sigtrap(int sig, siginfo_t *info, void *ctx_void) 480 { 481 ucontext_t *ctx = (ucontext_t *)ctx_void; 482 unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP]; 483 484 if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0) 485 num_vsyscall_traps++; 486 } 487 test_emulation(void)488 static void test_emulation(void) 489 { 490 time_t tmp; 491 bool is_native; 492 493 if (!vsyscall_map_x) { 494 ksft_test_result_skip("vsyscall_map_x isn't set\n"); 495 return; 496 } 497 498 ksft_print_msg("checking that vsyscalls are emulated\n"); 499 sethandler(SIGTRAP, sigtrap, 0); 500 set_eflags(get_eflags() | X86_EFLAGS_TF); 501 vtime(&tmp); 502 set_eflags(get_eflags() & ~X86_EFLAGS_TF); 503 504 /* 505 * If vsyscalls are emulated, we expect a single trap in the 506 * vsyscall page -- the call instruction will trap with RIP 507 * pointing to the entry point before emulation takes over. 508 * In native mode, we expect two traps, since whatever code 509 * the vsyscall page contains will be more than just a ret 510 * instruction. 511 */ 512 is_native = (num_vsyscall_traps > 1); 513 514 ksft_test_result(!is_native, "vsyscalls are %s (%d instructions in vsyscall page)\n", 515 (is_native ? "native" : "emulated"), (int)num_vsyscall_traps); 516 } 517 #endif 518 main(int argc,char ** argv)519 int main(int argc, char **argv) 520 { 521 int total_tests = TOTAL_TESTS; 522 523 ksft_print_header(); 524 ksft_set_plan(total_tests); 525 526 init_vdso(); 527 #ifdef __x86_64__ 528 init_vsys(); 529 #endif 530 531 test_gtod(); 532 test_time(); 533 test_getcpu(0); 534 test_getcpu(1); 535 536 #ifdef __x86_64__ 537 sethandler(SIGSEGV, sigsegv, 0); 538 test_vsys_r(); 539 test_vsys_x(); 540 test_process_vm_readv(); 541 test_emulation(); 542 #endif 543 544 ksft_finished(); 545 } 546