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- /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- * list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
- #include <AK/Assertions.h>
- #include <AK/ByteBuffer.h>
- #include <LibC/sys/arch/i386/regs.h>
- #include <LibCore/File.h>
- #include <LibELF/ELFImage.h>
- #include <signal.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <sys/ptrace.h>
- #include <sys/wait.h>
- #include <unistd.h>
- static int usage()
- {
- printf("usage: sdb [command...]\n");
- return 1;
- }
- static int g_pid = -1;
- static void handle_sigint(int)
- {
- if (g_pid == -1)
- return;
- if (ptrace(PT_DETACH, g_pid, 0, 0) == -1) {
- perror("detach");
- }
- }
- void run_child_and_attach(char** argv)
- {
- int pid = fork();
- if (!pid) {
- if (ptrace(PT_TRACE_ME, 0, 0, 0) == -1) {
- perror("traceme");
- return exit(1);
- }
- int rc = execvp(argv[1], &argv[1]);
- if (rc < 0) {
- perror("execvp");
- exit(1);
- }
- ASSERT_NOT_REACHED();
- }
- g_pid = pid;
- if (waitpid(pid, nullptr, WSTOPPED) != pid) {
- perror("waitpid");
- exit(1);
- }
- if (ptrace(PT_ATTACH, g_pid, 0, 0) == -1) {
- perror("attach");
- exit(1);
- }
- if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
- perror("waitpid");
- exit(1);
- }
- // we want to continue until the exit from the 'execve' sycsall
- // we do this to ensure that when we start debugging the process,
- // it executes the target image, and not the forked image of the debugger
- // NOTE: we only need to do this when we are debugging a new process (i.e not attaching to a process that's already running!)
- if (ptrace(PT_SYSCALL, g_pid, 0, 0) == -1) {
- perror("syscall");
- exit(1);
- }
- if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
- perror("wait_pid");
- exit(1);
- }
- }
- VirtualAddress get_entry_point(int pid)
- {
- auto path = String::format("/proc/%d/exe", pid);
- dbg() << "path: " << path;
- auto file = Core::File::construct(path);
- if (!file->open(Core::File::ReadOnly)) {
- fprintf(stderr, "Failed to open Debugged executable");
- exit(1);
- }
- auto data = file->read_all();
- dbg() << "data size:" << data.size();
- ELFImage elf(data.data(), data.size());
- return elf.entry();
- }
- int main(int argc, char** argv)
- {
- // TODO: pledge & unveil
- // TOOD: check that we didn't somehow hurt performance. boot seems slower? (or it's just laptop battey)
- if (argc == 1)
- return usage();
- struct sigaction sa;
- memset(&sa, 0, sizeof(struct sigaction));
- sa.sa_handler = handle_sigint;
- sigaction(SIGINT, &sa, nullptr);
- run_child_and_attach(argv);
- dbg() << "pid:" << g_pid;
- auto entry_point = get_entry_point(g_pid);
- dbg() << "entry point:" << entry_point;
- if (ptrace(PT_CONTINUE, g_pid, 0, 0) == -1) {
- perror("continue");
- }
- // wait for breakpoint
- if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
- perror("waitpid");
- return 1;
- }
- printf("hit breakpoint\n");
- PtraceRegisters regs;
- if (ptrace(PT_GETREGS, g_pid, ®s, 0) == -1) {
- perror("getregs");
- return 1;
- }
- printf("eip:0x%x\n", regs.eip);
- uint32_t data = ptrace(PT_PEEK, g_pid, (void*)regs.eip, 0);
- printf("peeked data: 0x%x\n", data);
- if (ptrace(PT_POKE, g_pid, (void*)regs.eip, data) < 0) {
- perror("poke");
- return 1;
- }
- if (ptrace(PT_CONTINUE, g_pid, 0, 0) == -1) {
- perror("continue");
- }
- if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
- perror("waitpid");
- return 1;
- }
- }
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