342 lines
10 KiB
C
342 lines
10 KiB
C
/*
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* Copyright (C) 2011 by Nelson Elhage
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <sys/ptrace.h>
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#include <asm/ptrace.h>
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#include <sys/types.h>
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#include <sys/user.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/syscall.h>
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#include <sys/mman.h>
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#include <assert.h>
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#include <stddef.h>
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//#include "ptrace.h"
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/*
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* RHEL 5's kernel supports these flags, but their libc doesn't ship a ptrace.h
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* that defines them. Define them here, and if our kernel doesn't support them,
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* we'll find out when PTRACE_SETOPTIONS fails.
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*/
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#ifndef PTRACE_O_TRACESYSGOOD
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#define PTRACE_O_TRACESYSGOOD 0x00000001
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#endif
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#ifndef PTRACE_O_TRACEFORK
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#define PTRACE_O_TRACEFORK 0x00000002
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#endif
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#ifndef PTRACE_EVENT_FORK
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#define PTRACE_EVENT_FORK 1
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#endif
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#define min(x, y) ({ \
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typeof(x) _min1 = (x); \
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typeof(y) _min2 = (y); \
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_min1 < _min2 ? _min1 : _min2; })
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static long __ptrace_command(struct ptrace_child *child, enum __ptrace_request req,
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void *, void*);
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#define ptrace_command(cld, req, ...) _ptrace_command(cld, req, ## __VA_ARGS__, NULL, NULL)
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#define _ptrace_command(cld, req, addr, data, ...) __ptrace_command((cld), (req), (void*)(addr), (void*)(data))
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struct ptrace_personality {
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size_t syscall_rv;
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size_t syscall_arg0;
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size_t syscall_arg1;
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size_t syscall_arg2;
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size_t syscall_arg3;
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size_t syscall_arg4;
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size_t syscall_arg5;
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size_t reg_ip;
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};
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static struct ptrace_personality *personality(struct ptrace_child *child);
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#if defined(__amd64__)
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//@include arch/amd64.h
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#elif defined(__i386__)
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//@include arch/i386.h
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#elif defined(__arm__)
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//@include arch/arm.h
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#else
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#error Unsupported architecture.
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#endif
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#ifndef ARCH_HAVE_MULTIPLE_PERSONALITIES
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int arch_get_personality(struct ptrace_child *child) {
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return 0;
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}
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struct syscall_numbers arch_syscall_numbers[] = {
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//@include arch/default-syscalls.h
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};
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#endif
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static struct ptrace_personality *personality(struct ptrace_child *child) {
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return &arch_personality[child->personality];
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}
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struct syscall_numbers *ptrace_syscall_numbers(struct ptrace_child *child) {
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return &arch_syscall_numbers[child->personality];
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}
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int ptrace_attach_child(struct ptrace_child *child, pid_t pid) {
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memset(child, 0, sizeof *child);
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child->pid = pid;
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if (ptrace_command(child, PTRACE_ATTACH) < 0)
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return -1;
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return ptrace_finish_attach(child, pid);
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}
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int ptrace_finish_attach(struct ptrace_child *child, pid_t pid) {
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memset(child, 0, sizeof *child);
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child->pid = pid;
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kill(pid, SIGCONT);
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if (ptrace_wait(child) < 0)
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goto detach;
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if (arch_get_personality(child))
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goto detach;
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if (ptrace_command(child, PTRACE_SETOPTIONS, 0,
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PTRACE_O_TRACESYSGOOD|PTRACE_O_TRACEFORK) < 0)
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goto detach;
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return 0;
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detach:
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/* Don't clobber child->error */
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ptrace(PTRACE_DETACH, child->pid, 0, 0);
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return -1;
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}
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int ptrace_detach_child(struct ptrace_child *child) {
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if (ptrace_command(child, PTRACE_DETACH, 0, 0) < 0)
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return -1;
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child->state = ptrace_detached;
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return 0;
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}
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int ptrace_wait(struct ptrace_child *child) {
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if (waitpid(child->pid, &child->status, 0) < 0) {
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child->error = errno;
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return -1;
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}
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if (WIFEXITED(child->status) || WIFSIGNALED(child->status)) {
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child->state = ptrace_exited;
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} else if (WIFSTOPPED(child->status)) {
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int sig = WSTOPSIG(child->status);
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if (sig & 0x80) {
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child->state = (child->state == ptrace_at_syscall) ?
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ptrace_after_syscall : ptrace_at_syscall;
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} else {
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if (sig == SIGTRAP && (((child->status >> 8) & PTRACE_EVENT_FORK) == PTRACE_EVENT_FORK))
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ptrace_command(child, PTRACE_GETEVENTMSG, 0, &child->forked_pid);
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if (child->state != ptrace_at_syscall)
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child->state = ptrace_stopped;
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}
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} else {
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child->error = EINVAL;
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return -1;
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}
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return 0;
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}
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int ptrace_advance_to_state(struct ptrace_child *child,
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enum child_state desired) {
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int err;
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while (child->state != desired) {
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switch(desired) {
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case ptrace_after_syscall:
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case ptrace_at_syscall:
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if (WIFSTOPPED(child->status) && WSTOPSIG(child->status) == SIGSEGV) {
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child->error = EAGAIN;
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return -1;
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}
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err = ptrace_command(child, PTRACE_SYSCALL, 0, 0);
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break;
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case ptrace_running:
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return ptrace_command(child, PTRACE_CONT, 0, 0);
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case ptrace_stopped:
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err = kill(child->pid, SIGSTOP);
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if (err < 0)
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child->error = errno;
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break;
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default:
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child->error = EINVAL;
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return -1;
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}
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if (err < 0)
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return err;
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if (ptrace_wait(child) < 0)
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return -1;
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}
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return 0;
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}
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int ptrace_save_regs(struct ptrace_child *child) {
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if (ptrace_advance_to_state(child, ptrace_at_syscall) < 0)
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return -1;
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if (ptrace_command(child, PTRACE_GETREGS, 0, &child->user) < 0)
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return -1;
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arch_fixup_regs(child);
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if (arch_save_syscall(child) < 0)
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return -1;
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return 0;
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}
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int ptrace_restore_regs(struct ptrace_child *child) {
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int err;
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err = ptrace_command(child, PTRACE_SETREGS, 0, &child->user);
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if (err < 0)
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return err;
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return arch_restore_syscall(child);
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}
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unsigned long ptrace_remote_syscall(struct ptrace_child *child,
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unsigned long sysno,
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unsigned long p0, unsigned long p1,
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unsigned long p2, unsigned long p3,
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unsigned long p4, unsigned long p5) {
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unsigned long rv;
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if (ptrace_advance_to_state(child, ptrace_at_syscall) < 0)
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return -1;
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#define setreg(r, v) do { \
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if (ptrace_command(child, PTRACE_POKEUSER, \
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personality(child)->r, \
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(v)) < 0) \
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return -1; \
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} while (0)
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if (arch_set_syscall(child, sysno) < 0)
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return -1;
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setreg(syscall_arg0, p0);
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setreg(syscall_arg1, p1);
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setreg(syscall_arg2, p2);
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setreg(syscall_arg3, p3);
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setreg(syscall_arg4, p4);
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setreg(syscall_arg5, p5);
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if (ptrace_advance_to_state(child, ptrace_after_syscall) < 0)
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return -1;
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rv = ptrace_command(child, PTRACE_PEEKUSER,
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personality(child)->syscall_rv);
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if (child->error)
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return -1;
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setreg(reg_ip, *(unsigned long*)((void*)&child->user +
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personality(child)->reg_ip));
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#undef setreg
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return rv;
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}
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int ptrace_memcpy_to_child(struct ptrace_child *child, child_addr_t dst, const void *src, size_t n) {
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unsigned long scratch;
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while (n >= sizeof(unsigned long)) {
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if (ptrace_command(child, PTRACE_POKEDATA, dst, *((unsigned long*)src)) < 0)
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return -1;
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dst += sizeof(unsigned long);
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src += sizeof(unsigned long);
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n -= sizeof(unsigned long);
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}
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if (n) {
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scratch = ptrace_command(child, PTRACE_PEEKDATA, dst);
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if (child->error)
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return -1;
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memcpy(&scratch, src, n);
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if (ptrace_command(child, PTRACE_POKEDATA, dst, scratch) < 0)
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return -1;
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}
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return 0;
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}
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int ptrace_memcpy_from_child(struct ptrace_child *child, void *dst, child_addr_t src, size_t n) {
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unsigned long scratch;
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while (n) {
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scratch = ptrace_command(child, PTRACE_PEEKDATA, src);
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if (child->error) return -1;
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memcpy(dst, &scratch, min(n, sizeof(unsigned long)));
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dst += sizeof(unsigned long);
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src += sizeof(unsigned long);
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if (n >= sizeof(unsigned long))
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n -= sizeof(unsigned long);
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else
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n = 0;
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}
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return 0;
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}
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static long __ptrace_command(struct ptrace_child *child, enum __ptrace_request req,
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void *addr, void *data) {
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long rv;
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errno = 0;
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rv = ptrace(req, child->pid, addr, data);
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child->error = errno;
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return rv;
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}
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#ifdef BUILD_PTRACE_MAIN
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int main(int argc, char **argv) {
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struct ptrace_child child;
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pid_t pid;
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if (argc < 2) {
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printf("Usage: %s pid\n", argv[0]);
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return 1;
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}
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pid = atoi(argv[1]);
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assert(!ptrace_attach_child(&child, pid));
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assert(!ptrace_save_regs(&child));
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printf("mmap = %lx\n", ptrace_remote_syscall(&child, mmap_syscall, 0,
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4096, PROT_READ|PROT_WRITE,
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MAP_ANONYMOUS|MAP_PRIVATE, 0, 0));
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reset_user_struct(&child.user);
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assert(!ptrace_restore_regs(&child));
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assert(!ptrace_detach_child(&child));
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return 0;
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}
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#endif
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