1// SPDX-License-Identifier: GPL-2.0 2#define _GNU_SOURCE 3 4#include <sys/ptrace.h> 5#include <sys/types.h> 6#include <sys/wait.h> 7#include <sys/syscall.h> 8#include <sys/user.h> 9#include <unistd.h> 10#include <errno.h> 11#include <stddef.h> 12#include <stdio.h> 13#include <err.h> 14#include <string.h> 15#include <asm/ptrace-abi.h> 16#include <sys/auxv.h> 17 18/* Bitness-agnostic defines for user_regs_struct fields. */ 19#ifdef __x86_64__ 20# define user_syscall_nr orig_rax 21# define user_arg0 rdi 22# define user_arg1 rsi 23# define user_arg2 rdx 24# define user_arg3 r10 25# define user_arg4 r8 26# define user_arg5 r9 27# define user_ip rip 28# define user_ax rax 29#else 30# define user_syscall_nr orig_eax 31# define user_arg0 ebx 32# define user_arg1 ecx 33# define user_arg2 edx 34# define user_arg3 esi 35# define user_arg4 edi 36# define user_arg5 ebp 37# define user_ip eip 38# define user_ax eax 39#endif 40 41static int nerrs = 0; 42 43struct syscall_args32 { 44 uint32_t nr, arg0, arg1, arg2, arg3, arg4, arg5; 45}; 46 47#ifdef __i386__ 48extern void sys32_helper(struct syscall_args32 *, void *); 49extern void int80_and_ret(void); 50#endif 51 52/* 53 * Helper to invoke int80 with controlled regs and capture the final regs. 54 */ 55static void do_full_int80(struct syscall_args32 *args) 56{ 57#ifdef __x86_64__ 58 register unsigned long bp asm("bp") = args->arg5; 59 asm volatile ("int $0x80" 60 : "+a" (args->nr), 61 "+b" (args->arg0), "+c" (args->arg1), "+d" (args->arg2), 62 "+S" (args->arg3), "+D" (args->arg4), "+r" (bp) 63 : : "r8", "r9", "r10", "r11"); 64 args->arg5 = bp; 65#else 66 sys32_helper(args, int80_and_ret); 67#endif 68} 69 70#ifdef __i386__ 71static void (*vsyscall32)(void); 72 73/* 74 * Nasty helper to invoke AT_SYSINFO (i.e. __kernel_vsyscall) with 75 * controlled regs and capture the final regs. This is so nasty that it 76 * crashes my copy of gdb :) 77 */ 78static void do_full_vsyscall32(struct syscall_args32 *args) 79{ 80 sys32_helper(args, vsyscall32); 81} 82#endif 83 84static siginfo_t wait_trap(pid_t chld) 85{ 86 siginfo_t si; 87 if (waitid(P_PID, chld, &si, WEXITED|WSTOPPED) != 0) 88 err(1, "waitid"); 89 if (si.si_pid != chld) 90 errx(1, "got unexpected pid in event\n"); 91 if (si.si_code != CLD_TRAPPED) 92 errx(1, "got unexpected event type %d\n", si.si_code); 93 return si; 94} 95 96static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), 97 int flags) 98{ 99 struct sigaction sa; 100 memset(&sa, 0, sizeof(sa)); 101 sa.sa_sigaction = handler; 102 sa.sa_flags = SA_SIGINFO | flags; 103 sigemptyset(&sa.sa_mask); 104 if (sigaction(sig, &sa, 0)) 105 err(1, "sigaction"); 106} 107 108static void setsigign(int sig, int flags) 109{ 110 struct sigaction sa; 111 memset(&sa, 0, sizeof(sa)); 112 sa.sa_sigaction = (void *)SIG_IGN; 113 sa.sa_flags = flags; 114 sigemptyset(&sa.sa_mask); 115 if (sigaction(sig, &sa, 0)) 116 err(1, "sigaction"); 117} 118 119static void clearhandler(int sig) 120{ 121 struct sigaction sa; 122 memset(&sa, 0, sizeof(sa)); 123 sa.sa_handler = SIG_DFL; 124 sigemptyset(&sa.sa_mask); 125 if (sigaction(sig, &sa, 0)) 126 err(1, "sigaction"); 127} 128 129#ifdef __x86_64__ 130# define REG_BP REG_RBP 131#else 132# define REG_BP REG_EBP 133#endif 134 135static void empty_handler(int sig, siginfo_t *si, void *ctx_void) 136{ 137} 138 139static void test_sys32_regs(void (*do_syscall)(struct syscall_args32 *)) 140{ 141 struct syscall_args32 args = { 142 .nr = 224, /* gettid */ 143 .arg0 = 10, .arg1 = 11, .arg2 = 12, 144 .arg3 = 13, .arg4 = 14, .arg5 = 15, 145 }; 146 147 do_syscall(&args); 148 149 if (args.nr != getpid() || 150 args.arg0 != 10 || args.arg1 != 11 || args.arg2 != 12 || 151 args.arg3 != 13 || args.arg4 != 14 || args.arg5 != 15) { 152 printf("[FAIL]\tgetpid() failed to preserve regs\n"); 153 nerrs++; 154 } else { 155 printf("[OK]\tgetpid() preserves regs\n"); 156 } 157 158 sethandler(SIGUSR1, empty_handler, 0); 159 160 args.nr = 37; /* kill */ 161 args.arg0 = getpid(); 162 args.arg1 = SIGUSR1; 163 do_syscall(&args); 164 if (args.nr != 0 || 165 args.arg0 != getpid() || args.arg1 != SIGUSR1 || args.arg2 != 12 || 166 args.arg3 != 13 || args.arg4 != 14 || args.arg5 != 15) { 167 printf("[FAIL]\tkill(getpid(), SIGUSR1) failed to preserve regs\n"); 168 nerrs++; 169 } else { 170 printf("[OK]\tkill(getpid(), SIGUSR1) preserves regs\n"); 171 } 172 clearhandler(SIGUSR1); 173} 174 175static void test_ptrace_syscall_restart(void) 176{ 177 printf("[RUN]\tptrace-induced syscall restart\n"); 178 pid_t chld = fork(); 179 if (chld < 0) 180 err(1, "fork"); 181 182 if (chld == 0) { 183 if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) 184 err(1, "PTRACE_TRACEME"); 185 186 pid_t pid = getpid(), tid = syscall(SYS_gettid); 187 188 printf("\tChild will make one syscall\n"); 189 syscall(SYS_tgkill, pid, tid, SIGSTOP); 190 191 syscall(SYS_gettid, 10, 11, 12, 13, 14, 15); 192 _exit(0); 193 } 194 195 int status; 196 197 /* Wait for SIGSTOP. */ 198 if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status)) 199 err(1, "waitpid"); 200 201 struct user_regs_struct regs; 202 203 printf("[RUN]\tSYSEMU\n"); 204 if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0) 205 err(1, "PTRACE_SYSEMU"); 206 wait_trap(chld); 207 208 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 209 err(1, "PTRACE_GETREGS"); 210 211 if (regs.user_syscall_nr != SYS_gettid || 212 regs.user_arg0 != 10 || regs.user_arg1 != 11 || 213 regs.user_arg2 != 12 || regs.user_arg3 != 13 || 214 regs.user_arg4 != 14 || regs.user_arg5 != 15) { 215 printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 216 nerrs++; 217 } else { 218 printf("[OK]\tInitial nr and args are correct\n"); 219 } 220 221 printf("[RUN]\tRestart the syscall (ip = 0x%lx)\n", 222 (unsigned long)regs.user_ip); 223 224 /* 225 * This does exactly what it appears to do if syscall is int80 or 226 * SYSCALL64. For SYSCALL32 or SYSENTER, though, this is highly 227 * magical. It needs to work so that ptrace and syscall restart 228 * work as expected. 229 */ 230 regs.user_ax = regs.user_syscall_nr; 231 regs.user_ip -= 2; 232 if (ptrace(PTRACE_SETREGS, chld, 0, ®s) != 0) 233 err(1, "PTRACE_SETREGS"); 234 235 if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0) 236 err(1, "PTRACE_SYSEMU"); 237 wait_trap(chld); 238 239 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 240 err(1, "PTRACE_GETREGS"); 241 242 if (regs.user_syscall_nr != SYS_gettid || 243 regs.user_arg0 != 10 || regs.user_arg1 != 11 || 244 regs.user_arg2 != 12 || regs.user_arg3 != 13 || 245 regs.user_arg4 != 14 || regs.user_arg5 != 15) { 246 printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 247 nerrs++; 248 } else { 249 printf("[OK]\tRestarted nr and args are correct\n"); 250 } 251 252 printf("[RUN]\tChange nr and args and restart the syscall (ip = 0x%lx)\n", 253 (unsigned long)regs.user_ip); 254 255 regs.user_ax = SYS_getpid; 256 regs.user_arg0 = 20; 257 regs.user_arg1 = 21; 258 regs.user_arg2 = 22; 259 regs.user_arg3 = 23; 260 regs.user_arg4 = 24; 261 regs.user_arg5 = 25; 262 regs.user_ip -= 2; 263 264 if (ptrace(PTRACE_SETREGS, chld, 0, ®s) != 0) 265 err(1, "PTRACE_SETREGS"); 266 267 if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0) 268 err(1, "PTRACE_SYSEMU"); 269 wait_trap(chld); 270 271 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 272 err(1, "PTRACE_GETREGS"); 273 274 if (regs.user_syscall_nr != SYS_getpid || 275 regs.user_arg0 != 20 || regs.user_arg1 != 21 || regs.user_arg2 != 22 || 276 regs.user_arg3 != 23 || regs.user_arg4 != 24 || regs.user_arg5 != 25) { 277 printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 278 nerrs++; 279 } else { 280 printf("[OK]\tReplacement nr and args are correct\n"); 281 } 282 283 if (ptrace(PTRACE_CONT, chld, 0, 0) != 0) 284 err(1, "PTRACE_CONT"); 285 if (waitpid(chld, &status, 0) != chld) 286 err(1, "waitpid"); 287 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { 288 printf("[FAIL]\tChild failed\n"); 289 nerrs++; 290 } else { 291 printf("[OK]\tChild exited cleanly\n"); 292 } 293} 294 295static void test_restart_under_ptrace(void) 296{ 297 printf("[RUN]\tkernel syscall restart under ptrace\n"); 298 pid_t chld = fork(); 299 if (chld < 0) 300 err(1, "fork"); 301 302 if (chld == 0) { 303 if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) 304 err(1, "PTRACE_TRACEME"); 305 306 pid_t pid = getpid(), tid = syscall(SYS_gettid); 307 308 printf("\tChild will take a nap until signaled\n"); 309 setsigign(SIGUSR1, SA_RESTART); 310 syscall(SYS_tgkill, pid, tid, SIGSTOP); 311 312 syscall(SYS_pause, 0, 0, 0, 0, 0, 0); 313 _exit(0); 314 } 315 316 int status; 317 318 /* Wait for SIGSTOP. */ 319 if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status)) 320 err(1, "waitpid"); 321 322 struct user_regs_struct regs; 323 324 printf("[RUN]\tSYSCALL\n"); 325 if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) 326 err(1, "PTRACE_SYSCALL"); 327 wait_trap(chld); 328 329 /* We should be stopped at pause(2) entry. */ 330 331 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 332 err(1, "PTRACE_GETREGS"); 333 334 if (regs.user_syscall_nr != SYS_pause || 335 regs.user_arg0 != 0 || regs.user_arg1 != 0 || 336 regs.user_arg2 != 0 || regs.user_arg3 != 0 || 337 regs.user_arg4 != 0 || regs.user_arg5 != 0) { 338 printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 339 nerrs++; 340 } else { 341 printf("[OK]\tInitial nr and args are correct\n"); 342 } 343 344 /* Interrupt it. */ 345 kill(chld, SIGUSR1); 346 347 /* Advance. We should be stopped at exit. */ 348 printf("[RUN]\tSYSCALL\n"); 349 if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) 350 err(1, "PTRACE_SYSCALL"); 351 wait_trap(chld); 352 353 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 354 err(1, "PTRACE_GETREGS"); 355 356 if (regs.user_syscall_nr != SYS_pause || 357 regs.user_arg0 != 0 || regs.user_arg1 != 0 || 358 regs.user_arg2 != 0 || regs.user_arg3 != 0 || 359 regs.user_arg4 != 0 || regs.user_arg5 != 0) { 360 printf("[FAIL]\tArgs after SIGUSR1 are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 361 nerrs++; 362 } else { 363 printf("[OK]\tArgs after SIGUSR1 are correct (ax = %ld)\n", 364 (long)regs.user_ax); 365 } 366 367 /* Poke the regs back in. This must not break anything. */ 368 if (ptrace(PTRACE_SETREGS, chld, 0, ®s) != 0) 369 err(1, "PTRACE_SETREGS"); 370 371 /* Catch the (ignored) SIGUSR1. */ 372 if (ptrace(PTRACE_CONT, chld, 0, 0) != 0) 373 err(1, "PTRACE_CONT"); 374 if (waitpid(chld, &status, 0) != chld) 375 err(1, "waitpid"); 376 if (!WIFSTOPPED(status)) { 377 printf("[FAIL]\tChild was stopped for SIGUSR1 (status = 0x%x)\n", status); 378 nerrs++; 379 } else { 380 printf("[OK]\tChild got SIGUSR1\n"); 381 } 382 383 /* The next event should be pause(2) again. */ 384 printf("[RUN]\tStep again\n"); 385 if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) 386 err(1, "PTRACE_SYSCALL"); 387 wait_trap(chld); 388 389 /* We should be stopped at pause(2) entry. */ 390 391 if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) 392 err(1, "PTRACE_GETREGS"); 393 394 if (regs.user_syscall_nr != SYS_pause || 395 regs.user_arg0 != 0 || regs.user_arg1 != 0 || 396 regs.user_arg2 != 0 || regs.user_arg3 != 0 || 397 regs.user_arg4 != 0 || regs.user_arg5 != 0) { 398 printf("[FAIL]\tpause did not restart (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); 399 nerrs++; 400 } else { 401 printf("[OK]\tpause(2) restarted correctly\n"); 402 } 403 404 /* Kill it. */ 405 kill(chld, SIGKILL); 406 if (waitpid(chld, &status, 0) != chld) 407 err(1, "waitpid"); 408} 409 410int main() 411{ 412 printf("[RUN]\tCheck int80 return regs\n"); 413 test_sys32_regs(do_full_int80); 414 415#if defined(__i386__) && (!defined(__GLIBC__) || __GLIBC__ > 2 || __GLIBC_MINOR__ >= 16) 416 vsyscall32 = (void *)getauxval(AT_SYSINFO); 417 if (vsyscall32) { 418 printf("[RUN]\tCheck AT_SYSINFO return regs\n"); 419 test_sys32_regs(do_full_vsyscall32); 420 } else { 421 printf("[SKIP]\tAT_SYSINFO is not available\n"); 422 } 423#endif 424 425 test_ptrace_syscall_restart(); 426 427 test_restart_under_ptrace(); 428 429 return 0; 430} 431