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

   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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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, &regs) != 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