Check whether PTRACE_GET_SYSCALL_INFO is supported by the kernel
The result of this check is going to be used by subsequent commits. * ptrace_syscall_info.c: New file. * ptrace_syscall_info.h: Likewise. * Makefile.am (strace_SOURCES): Add them. * strace.c: Include "ptrace_syscall_info.h". (init): Call test_ptrace_get_syscall_info.
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86d073674e
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@ -249,6 +249,8 @@ strace_SOURCES = \
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process_vm.c \
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ptp.c \
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ptrace.h \
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ptrace_syscall_info.c \
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ptrace_syscall_info.h \
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quota.c \
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random_ioctl.c \
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readahead.c \
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252
ptrace_syscall_info.c
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252
ptrace_syscall_info.c
Normal file
@ -0,0 +1,252 @@
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/*
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* Copyright (c) 2018 Dmitry V. Levin <ldv@altlinux.org>
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* All rights reserved.
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*/
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#include "defs.h"
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#include "kill_save_errno.h"
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#include "ptrace.h"
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#include "ptrace_syscall_info.h"
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#include "scno.h"
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#include <signal.h>
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#include <sys/wait.h>
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bool ptrace_get_syscall_info_supported;
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static int
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kill_tracee(pid_t pid)
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{
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return kill_save_errno(pid, SIGKILL);
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}
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#define FAIL do { ptrace_stop = -1U; goto done; } while (0)
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static const unsigned int expected_none_size =
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offsetof(struct ptrace_syscall_info, entry);
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static const unsigned int expected_entry_size =
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offsetofend(struct ptrace_syscall_info, entry.args);
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static const unsigned int expected_exit_size =
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offsetofend(struct ptrace_syscall_info, exit.is_error);
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/*
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* Test that PTRACE_GET_SYSCALL_INFO API is supported by the kernel, and
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* that the semantics implemented in the kernel matches our expectations.
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*/
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bool
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test_ptrace_get_syscall_info(void)
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{
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static const unsigned long args[][7] = {
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/* a sequence of architecture-agnostic syscalls */
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{
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__NR_chdir,
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(unsigned long) "",
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0xbad1fed1,
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0xbad2fed2,
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0xbad3fed3,
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0xbad4fed4,
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0xbad5fed5
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},
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{
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__NR_gettid,
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0xcaf0bea0,
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0xcaf1bea1,
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0xcaf2bea2,
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0xcaf3bea3,
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0xcaf4bea4,
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0xcaf5bea5
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},
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{
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__NR_exit_group,
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0,
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0xfac1c0d1,
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0xfac2c0d2,
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0xfac3c0d3,
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0xfac4c0d4,
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0xfac5c0d5
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}
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};
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const unsigned long *exp_args;
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int pid = fork();
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if (pid < 0)
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perror_func_msg_and_die("fork");
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if (pid == 0) {
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/* get the pid before PTRACE_TRACEME */
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pid = getpid();
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if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) {
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/* exit with a nonzero exit status */
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perror_func_msg_and_die("PTRACE_TRACEME");
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}
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kill(pid, SIGSTOP);
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for (unsigned int i = 0; i < ARRAY_SIZE(args); ++i) {
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syscall(args[i][0],
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args[i][1], args[i][2], args[i][3],
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args[i][4], args[i][5], args[i][6]);
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}
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/* unreachable */
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_exit(1);
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}
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const struct {
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unsigned int is_error;
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int rval;
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} *exp_param, exit_param[] = {
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{ 1, -ENOENT }, /* chdir */
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{ 0, pid } /* gettid */
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};
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unsigned int ptrace_stop;
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for (ptrace_stop = 0; ; ++ptrace_stop) {
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struct ptrace_syscall_info info = {
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.op = 0xff /* invalid PTRACE_SYSCALL_INFO_* op */
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};
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const size_t size = sizeof(info);
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int status;
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long rc = waitpid(pid, &status, 0);
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if (rc != pid) {
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/* cannot happen */
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kill_tracee(pid);
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perror_func_msg_and_die("#%d: unexpected wait result"
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" %ld", ptrace_stop, rc);
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}
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if (WIFEXITED(status)) {
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/* tracee is no more */
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pid = 0;
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if (WEXITSTATUS(status) == 0)
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break;
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debug_func_msg("#%d: unexpected exit status %u",
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ptrace_stop, WEXITSTATUS(status));
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FAIL;
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}
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if (WIFSIGNALED(status)) {
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/* tracee is no more */
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pid = 0;
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debug_func_msg("#%d: unexpected signal %u",
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ptrace_stop, WTERMSIG(status));
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FAIL;
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}
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if (!WIFSTOPPED(status)) {
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/* cannot happen */
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kill_tracee(pid);
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error_func_msg_and_die("#%d: unexpected wait status"
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" %#x", ptrace_stop, status);
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}
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switch (WSTOPSIG(status)) {
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case SIGSTOP:
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if (ptrace_stop) {
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debug_func_msg("#%d: unexpected signal stop",
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ptrace_stop);
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FAIL;
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}
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if (ptrace(PTRACE_SETOPTIONS, pid, 0L,
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PTRACE_O_TRACESYSGOOD) < 0) {
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/* cannot happen */
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kill_tracee(pid);
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perror_func_msg_and_die("PTRACE_SETOPTIONS");
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}
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rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid,
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(void *) size, &info);
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if (rc < 0) {
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debug_perror_msg("PTRACE_GET_SYSCALL_INFO");
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FAIL;
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}
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if (rc < (long) expected_none_size
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|| info.op != PTRACE_SYSCALL_INFO_NONE
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|| !info.arch
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|| !info.instruction_pointer
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|| !info.stack_pointer) {
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debug_func_msg("signal stop mismatch");
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FAIL;
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}
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break;
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case SIGTRAP | 0x80:
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rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid,
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(void *) size, &info);
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if (rc < 0) {
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debug_perror_msg("#%d: PTRACE_GET_SYSCALL_INFO",
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ptrace_stop);
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FAIL;
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}
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switch (ptrace_stop) {
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case 1: /* entering chdir */
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case 3: /* entering gettid */
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case 5: /* entering exit_group */
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exp_args = args[ptrace_stop / 2];
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if (rc < (long) expected_entry_size
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|| info.op != PTRACE_SYSCALL_INFO_ENTRY
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|| !info.arch
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|| !info.instruction_pointer
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|| !info.stack_pointer
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|| (info.entry.nr != exp_args[0])
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|| (info.entry.args[0] != exp_args[1])
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|| (info.entry.args[1] != exp_args[2])
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|| (info.entry.args[2] != exp_args[3])
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|| (info.entry.args[3] != exp_args[4])
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|| (info.entry.args[4] != exp_args[5])
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|| (info.entry.args[5] != exp_args[6])) {
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debug_func_msg("#%d: entry stop"
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" mismatch",
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ptrace_stop);
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FAIL;
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}
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break;
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case 2: /* exiting chdir */
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case 4: /* exiting gettid */
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exp_param = &exit_param[ptrace_stop / 2 - 1];
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if (rc < (long) expected_exit_size
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|| info.op != PTRACE_SYSCALL_INFO_EXIT
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|| !info.arch
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|| !info.instruction_pointer
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|| !info.stack_pointer
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|| info.exit.is_error != exp_param->is_error
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|| info.exit.rval != exp_param->rval) {
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debug_func_msg("#%d: exit stop"
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" mismatch",
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ptrace_stop);
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FAIL;
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}
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break;
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default:
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debug_func_msg("#%d: unexpected syscall stop",
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ptrace_stop);
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FAIL;
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}
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break;
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default:
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debug_func_msg("#%d: unexpected stop signal %#x",
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ptrace_stop, WSTOPSIG(status));
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FAIL;
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}
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if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) {
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/* cannot happen */
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kill_tracee(pid);
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perror_func_msg_and_die("PTRACE_SYSCALL");
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}
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}
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done:
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if (pid) {
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kill_tracee(pid);
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waitpid(pid, NULL, 0);
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ptrace_stop = -1U;
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}
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ptrace_get_syscall_info_supported =
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ptrace_stop == ARRAY_SIZE(args) * 2;
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if (ptrace_get_syscall_info_supported)
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debug_msg("PTRACE_GET_SYSCALL_INFO works");
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else
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debug_msg("PTRACE_GET_SYSCALL_INFO does not work");
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return ptrace_get_syscall_info_supported;
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}
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14
ptrace_syscall_info.h
Normal file
14
ptrace_syscall_info.h
Normal file
@ -0,0 +1,14 @@
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/*
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* Copyright (c) 2018 Dmitry V. Levin <ldv@altlinux.org>
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* All rights reserved.
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*/
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#ifndef STRACE_PTRACE_SYSCALL_INFO_H
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#define STRACE_PTRACE_SYSCALL_INFO_H
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extern bool ptrace_get_syscall_info_supported;
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extern bool test_ptrace_get_syscall_info(void);
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#endif /* !STRACE_PTRACE_SYSCALL_INFO_H */
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8
strace.c
8
strace.c
@ -35,6 +35,7 @@
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#include "largefile_wrappers.h"
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#include "mmap_cache.h"
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#include "number_set.h"
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#include "ptrace_syscall_info.h"
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#include "scno.h"
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#include "printsiginfo.h"
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#include "trace_event.h"
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@ -1800,6 +1801,13 @@ init(int argc, char *argv[])
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debug_msg("ptrace_setoptions = %#x", ptrace_setoptions);
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test_ptrace_seize();
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/*
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* NOMMU provides no forks necessary for PTRACE_GET_SYSCALL_INFO test,
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* leave the default unchanged.
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*/
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if (!NOMMU_SYSTEM)
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test_ptrace_get_syscall_info();
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/*
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* Is something weird with our stdin and/or stdout -
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* for example, may they be not open? In this case,
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