LXR linux/tools/testing/selftests/x86/ptrace

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