f39383103b
Static binaries don't get the signal handler installed (that's done by the dynamic linker) so we don't need to worry about seeing SIGPIPE crashes from old binaries. Bug: http://b/20659371 Change-Id: I3b5566634fadd3e822262561188d29814bccd1fd
593 lines
18 KiB
C++
593 lines
18 KiB
C++
/*
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* Copyright 2006, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <signal.h>
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#include <pthread.h>
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#include <stdarg.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <time.h>
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#include <sys/ptrace.h>
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#include <sys/wait.h>
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#include <elf.h>
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#include <sys/stat.h>
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#include <sys/poll.h>
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#include <selinux/android.h>
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#include <log/logger.h>
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#include <cutils/sockets.h>
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#include <cutils/properties.h>
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#include <cutils/debugger.h>
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#include <linux/input.h>
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#include <private/android_filesystem_config.h>
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#include "backtrace.h"
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#include "getevent.h"
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#include "tombstone.h"
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#include "utility.h"
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// If the 32 bit executable is compiled on a 64 bit system,
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// use the 32 bit socket name.
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#if defined(TARGET_IS_64_BIT) && !defined(__LP64__)
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#define SOCKET_NAME DEBUGGER32_SOCKET_NAME
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#else
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#define SOCKET_NAME DEBUGGER_SOCKET_NAME
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#endif
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struct debugger_request_t {
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debugger_action_t action;
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pid_t pid, tid;
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uid_t uid, gid;
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uintptr_t abort_msg_address;
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int32_t original_si_code;
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};
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static void wait_for_user_action(const debugger_request_t& request) {
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// Explain how to attach the debugger.
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ALOGI("***********************************************************\n"
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"* Process %d has been suspended while crashing.\n"
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"* To attach gdbserver and start gdb, run this on the host:\n"
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"*\n"
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"* gdbclient %d\n"
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"*\n"
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"* Wait for gdb to start, then press the VOLUME DOWN key\n"
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"* to let the process continue crashing.\n"
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"***********************************************************",
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request.pid, request.tid);
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// Wait for VOLUME DOWN.
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if (init_getevent() == 0) {
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while (true) {
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input_event e;
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if (get_event(&e, -1) == 0) {
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if (e.type == EV_KEY && e.code == KEY_VOLUMEDOWN && e.value == 0) {
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break;
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}
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}
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}
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uninit_getevent();
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}
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ALOGI("debuggerd resuming process %d", request.pid);
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}
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static int get_process_info(pid_t tid, pid_t* out_pid, uid_t* out_uid, uid_t* out_gid) {
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char path[64];
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snprintf(path, sizeof(path), "/proc/%d/status", tid);
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FILE* fp = fopen(path, "r");
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if (!fp) {
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return -1;
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}
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int fields = 0;
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char line[1024];
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while (fgets(line, sizeof(line), fp)) {
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size_t len = strlen(line);
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if (len > 6 && !memcmp(line, "Tgid:\t", 6)) {
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*out_pid = atoi(line + 6);
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fields |= 1;
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} else if (len > 5 && !memcmp(line, "Uid:\t", 5)) {
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*out_uid = atoi(line + 5);
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fields |= 2;
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} else if (len > 5 && !memcmp(line, "Gid:\t", 5)) {
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*out_gid = atoi(line + 5);
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fields |= 4;
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}
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}
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fclose(fp);
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return fields == 7 ? 0 : -1;
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}
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/*
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* Corresponds with debugger_action_t enum type in
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* include/cutils/debugger.h.
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*/
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static const char *debuggerd_perms[] = {
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NULL, /* crash is only used on self, no check applied */
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"dump_tombstone",
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"dump_backtrace"
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};
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static bool selinux_action_allowed(int s, pid_t tid, debugger_action_t action)
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{
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char *scon = NULL, *tcon = NULL;
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const char *tclass = "debuggerd";
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const char *perm;
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bool allowed = false;
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if (action <= 0 || action >= (sizeof(debuggerd_perms)/sizeof(debuggerd_perms[0]))) {
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ALOGE("SELinux: No permission defined for debugger action %d", action);
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return false;
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}
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perm = debuggerd_perms[action];
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if (getpeercon(s, &scon) < 0) {
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ALOGE("Cannot get peer context from socket\n");
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goto out;
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}
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if (getpidcon(tid, &tcon) < 0) {
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ALOGE("Cannot get context for tid %d\n", tid);
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goto out;
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}
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allowed = (selinux_check_access(scon, tcon, tclass, perm, NULL) == 0);
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out:
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freecon(scon);
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freecon(tcon);
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return allowed;
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}
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static int read_request(int fd, debugger_request_t* out_request) {
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ucred cr;
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socklen_t len = sizeof(cr);
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int status = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
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if (status != 0) {
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ALOGE("cannot get credentials");
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return -1;
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}
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ALOGV("reading tid");
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fcntl(fd, F_SETFL, O_NONBLOCK);
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pollfd pollfds[1];
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pollfds[0].fd = fd;
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pollfds[0].events = POLLIN;
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pollfds[0].revents = 0;
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status = TEMP_FAILURE_RETRY(poll(pollfds, 1, 3000));
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if (status != 1) {
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ALOGE("timed out reading tid (from pid=%d uid=%d)\n", cr.pid, cr.uid);
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return -1;
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}
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debugger_msg_t msg;
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memset(&msg, 0, sizeof(msg));
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status = TEMP_FAILURE_RETRY(read(fd, &msg, sizeof(msg)));
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if (status < 0) {
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ALOGE("read failure? %s (pid=%d uid=%d)\n", strerror(errno), cr.pid, cr.uid);
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return -1;
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}
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if (status != sizeof(debugger_msg_t)) {
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ALOGE("invalid crash request of size %d (from pid=%d uid=%d)\n", status, cr.pid, cr.uid);
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return -1;
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}
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out_request->action = static_cast<debugger_action_t>(msg.action);
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out_request->tid = msg.tid;
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out_request->pid = cr.pid;
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out_request->uid = cr.uid;
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out_request->gid = cr.gid;
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out_request->abort_msg_address = msg.abort_msg_address;
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out_request->original_si_code = msg.original_si_code;
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if (msg.action == DEBUGGER_ACTION_CRASH) {
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// Ensure that the tid reported by the crashing process is valid.
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char buf[64];
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struct stat s;
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snprintf(buf, sizeof buf, "/proc/%d/task/%d", out_request->pid, out_request->tid);
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if (stat(buf, &s)) {
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ALOGE("tid %d does not exist in pid %d. ignoring debug request\n",
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out_request->tid, out_request->pid);
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return -1;
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}
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} else if (cr.uid == 0
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|| (cr.uid == AID_SYSTEM && msg.action == DEBUGGER_ACTION_DUMP_BACKTRACE)) {
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// Only root or system can ask us to attach to any process and dump it explicitly.
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// However, system is only allowed to collect backtraces but cannot dump tombstones.
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status = get_process_info(out_request->tid, &out_request->pid,
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&out_request->uid, &out_request->gid);
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if (status < 0) {
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ALOGE("tid %d does not exist. ignoring explicit dump request\n", out_request->tid);
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return -1;
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}
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if (!selinux_action_allowed(fd, out_request->tid, out_request->action))
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return -1;
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} else {
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// No one else is allowed to dump arbitrary processes.
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return -1;
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}
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return 0;
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}
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static bool should_attach_gdb(debugger_request_t* request) {
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if (request->action == DEBUGGER_ACTION_CRASH) {
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return property_get_bool("debug.debuggerd.wait_for_gdb", false);
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}
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return false;
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}
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#if defined(__LP64__)
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static bool is32bit(pid_t tid) {
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char* exeline;
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if (asprintf(&exeline, "/proc/%d/exe", tid) == -1) {
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return false;
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}
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int fd = TEMP_FAILURE_RETRY(open(exeline, O_RDONLY | O_CLOEXEC));
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int saved_errno = errno;
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free(exeline);
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if (fd == -1) {
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ALOGW("Failed to open /proc/%d/exe %s", tid, strerror(saved_errno));
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return false;
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}
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char ehdr[EI_NIDENT];
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ssize_t bytes = TEMP_FAILURE_RETRY(read(fd, &ehdr, sizeof(ehdr)));
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close(fd);
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if (bytes != (ssize_t) sizeof(ehdr) || memcmp(ELFMAG, ehdr, SELFMAG) != 0) {
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return false;
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}
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if (ehdr[EI_CLASS] == ELFCLASS32) {
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return true;
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}
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return false;
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}
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static void redirect_to_32(int fd, debugger_request_t* request) {
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debugger_msg_t msg;
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memset(&msg, 0, sizeof(msg));
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msg.tid = request->tid;
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msg.action = request->action;
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int sock_fd = socket_local_client(DEBUGGER32_SOCKET_NAME, ANDROID_SOCKET_NAMESPACE_ABSTRACT,
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SOCK_STREAM | SOCK_CLOEXEC);
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if (sock_fd < 0) {
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ALOGE("Failed to connect to debuggerd32: %s", strerror(errno));
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return;
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}
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if (TEMP_FAILURE_RETRY(write(sock_fd, &msg, sizeof(msg))) != (ssize_t) sizeof(msg)) {
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ALOGE("Failed to write request to debuggerd32 socket: %s", strerror(errno));
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close(sock_fd);
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return;
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}
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char ack;
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if (TEMP_FAILURE_RETRY(read(sock_fd, &ack, 1)) == -1) {
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ALOGE("Failed to read ack from debuggerd32 socket: %s", strerror(errno));
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close(sock_fd);
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return;
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}
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char buffer[1024];
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ssize_t bytes_read;
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while ((bytes_read = TEMP_FAILURE_RETRY(read(sock_fd, buffer, sizeof(buffer)))) > 0) {
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ssize_t bytes_to_send = bytes_read;
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ssize_t bytes_written;
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do {
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bytes_written = TEMP_FAILURE_RETRY(write(fd, buffer + bytes_read - bytes_to_send,
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bytes_to_send));
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if (bytes_written == -1) {
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if (errno == EAGAIN) {
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// Retry the write.
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continue;
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}
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ALOGE("Error while writing data to fd: %s", strerror(errno));
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break;
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}
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bytes_to_send -= bytes_written;
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} while (bytes_written != 0 && bytes_to_send > 0);
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if (bytes_to_send != 0) {
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ALOGE("Failed to write all data to fd: read %zd, sent %zd", bytes_read, bytes_to_send);
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break;
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}
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}
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close(sock_fd);
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}
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#endif
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static void handle_request(int fd) {
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ALOGV("handle_request(%d)\n", fd);
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debugger_request_t request;
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memset(&request, 0, sizeof(request));
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int status = read_request(fd, &request);
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if (!status) {
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ALOGV("BOOM: pid=%d uid=%d gid=%d tid=%d\n",
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request.pid, request.uid, request.gid, request.tid);
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#if defined(__LP64__)
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// On 64 bit systems, requests to dump 32 bit and 64 bit tids come
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// to the 64 bit debuggerd. If the process is a 32 bit executable,
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// redirect the request to the 32 bit debuggerd.
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if (is32bit(request.tid)) {
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// Only dump backtrace and dump tombstone requests can be redirected.
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if (request.action == DEBUGGER_ACTION_DUMP_BACKTRACE
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|| request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
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redirect_to_32(fd, &request);
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} else {
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ALOGE("debuggerd: Not allowed to redirect action %d to 32 bit debuggerd\n",
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request.action);
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}
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close(fd);
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return;
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}
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#endif
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// At this point, the thread that made the request is blocked in
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// a read() call. If the thread has crashed, then this gives us
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// time to PTRACE_ATTACH to it before it has a chance to really fault.
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//
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// The PTRACE_ATTACH sends a SIGSTOP to the target process, but it
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// won't necessarily have stopped by the time ptrace() returns. (We
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// currently assume it does.) We write to the file descriptor to
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// ensure that it can run as soon as we call PTRACE_CONT below.
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// See details in bionic/libc/linker/debugger.c, in function
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// debugger_signal_handler().
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if (ptrace(PTRACE_ATTACH, request.tid, 0, 0)) {
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ALOGE("ptrace attach failed: %s\n", strerror(errno));
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} else {
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bool detach_failed = false;
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bool tid_unresponsive = false;
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bool attach_gdb = should_attach_gdb(&request);
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if (TEMP_FAILURE_RETRY(write(fd, "\0", 1)) != 1) {
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ALOGE("failed responding to client: %s\n", strerror(errno));
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} else {
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char* tombstone_path = NULL;
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if (request.action == DEBUGGER_ACTION_CRASH) {
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close(fd);
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fd = -1;
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}
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int total_sleep_time_usec = 0;
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for (;;) {
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int signal = wait_for_sigstop(request.tid, &total_sleep_time_usec, &detach_failed);
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if (signal == -1) {
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tid_unresponsive = true;
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break;
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}
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switch (signal) {
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case SIGSTOP:
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if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
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ALOGV("stopped -- dumping to tombstone\n");
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tombstone_path = engrave_tombstone(request.pid, request.tid,
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signal, request.original_si_code,
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request.abort_msg_address, true,
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&detach_failed, &total_sleep_time_usec);
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} else if (request.action == DEBUGGER_ACTION_DUMP_BACKTRACE) {
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ALOGV("stopped -- dumping to fd\n");
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dump_backtrace(fd, -1, request.pid, request.tid, &detach_failed,
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&total_sleep_time_usec);
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} else {
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ALOGV("stopped -- continuing\n");
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status = ptrace(PTRACE_CONT, request.tid, 0, 0);
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if (status) {
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ALOGE("ptrace continue failed: %s\n", strerror(errno));
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}
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continue; // loop again
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}
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break;
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case SIGABRT:
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case SIGBUS:
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case SIGFPE:
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case SIGILL:
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case SIGSEGV:
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#ifdef SIGSTKFLT
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case SIGSTKFLT:
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#endif
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case SIGTRAP:
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ALOGV("stopped -- fatal signal\n");
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// Send a SIGSTOP to the process to make all of
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// the non-signaled threads stop moving. Without
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// this we get a lot of "ptrace detach failed:
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// No such process".
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kill(request.pid, SIGSTOP);
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// don't dump sibling threads when attaching to GDB because it
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// makes the process less reliable, apparently...
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tombstone_path = engrave_tombstone(request.pid, request.tid,
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signal, request.original_si_code,
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request.abort_msg_address, !attach_gdb,
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&detach_failed, &total_sleep_time_usec);
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break;
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default:
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ALOGE("process stopped due to unexpected signal %d\n", signal);
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break;
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}
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break;
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}
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if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
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if (tombstone_path) {
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write(fd, tombstone_path, strlen(tombstone_path));
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}
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close(fd);
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fd = -1;
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}
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free(tombstone_path);
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}
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if (!tid_unresponsive) {
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ALOGV("detaching");
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if (attach_gdb) {
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// stop the process so we can debug
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kill(request.pid, SIGSTOP);
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}
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if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {
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ALOGE("ptrace detach from %d failed: %s", request.tid, strerror(errno));
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detach_failed = true;
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} else if (attach_gdb) {
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// if debug.db.uid is set, its value indicates if we should wait
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// for user action for the crashing process.
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// in this case, we log a message and turn the debug LED on
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// waiting for a gdb connection (for instance)
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wait_for_user_action(request);
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}
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}
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// resume stopped process (so it can crash in peace).
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kill(request.pid, SIGCONT);
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// If we didn't successfully detach, we're still the parent, and the
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// actual parent won't receive a death notification via wait(2). At this point
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// there's not much we can do about that.
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if (detach_failed) {
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ALOGE("debuggerd committing suicide to free the zombie!\n");
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kill(getpid(), SIGKILL);
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}
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}
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}
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if (fd >= 0) {
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close(fd);
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}
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}
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static int do_server() {
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// debuggerd crashes can't be reported to debuggerd.
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// Reset all of the crash handlers.
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signal(SIGABRT, SIG_DFL);
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signal(SIGBUS, SIG_DFL);
|
|
signal(SIGFPE, SIG_DFL);
|
|
signal(SIGILL, SIG_DFL);
|
|
signal(SIGSEGV, SIG_DFL);
|
|
#ifdef SIGSTKFLT
|
|
signal(SIGSTKFLT, SIG_DFL);
|
|
#endif
|
|
signal(SIGTRAP, SIG_DFL);
|
|
|
|
// Ignore failed writes to closed sockets
|
|
signal(SIGPIPE, SIG_IGN);
|
|
|
|
int logsocket = socket_local_client("logd", ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
|
|
if (logsocket < 0) {
|
|
logsocket = -1;
|
|
} else {
|
|
fcntl(logsocket, F_SETFD, FD_CLOEXEC);
|
|
}
|
|
|
|
struct sigaction act;
|
|
act.sa_handler = SIG_DFL;
|
|
sigemptyset(&act.sa_mask);
|
|
sigaddset(&act.sa_mask,SIGCHLD);
|
|
act.sa_flags = SA_NOCLDWAIT;
|
|
sigaction(SIGCHLD, &act, 0);
|
|
|
|
int s = socket_local_server(SOCKET_NAME, ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
|
|
if (s < 0)
|
|
return 1;
|
|
fcntl(s, F_SETFD, FD_CLOEXEC);
|
|
|
|
ALOGI("debuggerd: " __DATE__ " " __TIME__ "\n");
|
|
|
|
for (;;) {
|
|
sockaddr addr;
|
|
socklen_t alen = sizeof(addr);
|
|
|
|
ALOGV("waiting for connection\n");
|
|
int fd = accept(s, &addr, &alen);
|
|
if (fd < 0) {
|
|
ALOGV("accept failed: %s\n", strerror(errno));
|
|
continue;
|
|
}
|
|
|
|
fcntl(fd, F_SETFD, FD_CLOEXEC);
|
|
|
|
handle_request(fd);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int do_explicit_dump(pid_t tid, bool dump_backtrace) {
|
|
fprintf(stdout, "Sending request to dump task %d.\n", tid);
|
|
|
|
if (dump_backtrace) {
|
|
fflush(stdout);
|
|
if (dump_backtrace_to_file(tid, fileno(stdout)) < 0) {
|
|
fputs("Error dumping backtrace.\n", stderr);
|
|
return 1;
|
|
}
|
|
} else {
|
|
char tombstone_path[PATH_MAX];
|
|
if (dump_tombstone(tid, tombstone_path, sizeof(tombstone_path)) < 0) {
|
|
fputs("Error dumping tombstone.\n", stderr);
|
|
return 1;
|
|
}
|
|
fprintf(stderr, "Tombstone written to: %s\n", tombstone_path);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void usage() {
|
|
fputs("Usage: -b [<tid>]\n"
|
|
" -b dump backtrace to console, otherwise dump full tombstone file\n"
|
|
"\n"
|
|
"If tid specified, sends a request to debuggerd to dump that task.\n"
|
|
"Otherwise, starts the debuggerd server.\n", stderr);
|
|
}
|
|
|
|
int main(int argc, char** argv) {
|
|
union selinux_callback cb;
|
|
if (argc == 1) {
|
|
cb.func_log = selinux_log_callback;
|
|
selinux_set_callback(SELINUX_CB_LOG, cb);
|
|
return do_server();
|
|
}
|
|
|
|
bool dump_backtrace = false;
|
|
bool have_tid = false;
|
|
pid_t tid = 0;
|
|
for (int i = 1; i < argc; i++) {
|
|
if (!strcmp(argv[i], "-b")) {
|
|
dump_backtrace = true;
|
|
} else if (!have_tid) {
|
|
tid = atoi(argv[i]);
|
|
have_tid = true;
|
|
} else {
|
|
usage();
|
|
return 1;
|
|
}
|
|
}
|
|
if (!have_tid) {
|
|
usage();
|
|
return 1;
|
|
}
|
|
return do_explicit_dump(tid, dump_backtrace);
|
|
}
|