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platform_system_core/debuggerd/libdebuggerd/utility.cpp
Josh Gao 1cc7bd80a6 debuggerd: remove maximum abort message length. 
Let the logging implementation be the imposer of limits.

Bug: http://b/64759619
Test: debuggerd_test
Change-Id: I8bc73bf2301ce071668993b740880224846a4e75
2018-04-13 17:34:20 -07:00

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/*
* Copyright 2008, The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "DEBUG"
#include "libdebuggerd/utility.h"
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <backtrace/Backtrace.h>
#include <debuggerd/handler.h>
#include <log/log.h>
#include <unwindstack/Memory.h>
using android::base::unique_fd;
// Whitelist output desired in the logcat output.
bool is_allowed_in_logcat(enum logtype ltype) {
if ((ltype == HEADER)
|| (ltype == REGISTERS)
|| (ltype == BACKTRACE)) {
return true;
}
return false;
}
static bool should_write_to_kmsg() {
// Write to kmsg if tombstoned isn't up, and we're able to do so.
if (!android::base::GetBoolProperty("ro.debuggable", false)) {
return false;
}
if (android::base::GetProperty("init.svc.tombstoned", "") == "running") {
return false;
}
return true;
}
__attribute__((__weak__, visibility("default")))
void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) {
bool write_to_tombstone = (log->tfd != -1);
bool write_to_logcat = is_allowed_in_logcat(ltype)
&& log->crashed_tid != -1
&& log->current_tid != -1
&& (log->crashed_tid == log->current_tid);
static bool write_to_kmsg = should_write_to_kmsg();
std::string msg;
va_list ap;
va_start(ap, fmt);
android::base::StringAppendV(&msg, fmt, ap);
va_end(ap);
if (msg.empty()) return;
if (write_to_tombstone) {
TEMP_FAILURE_RETRY(write(log->tfd, msg.c_str(), msg.size()));
}
if (write_to_logcat) {
__android_log_buf_write(LOG_ID_CRASH, ANDROID_LOG_FATAL, LOG_TAG, msg.c_str());
if (log->amfd_data != nullptr) {
*log->amfd_data += msg;
}
if (write_to_kmsg) {
unique_fd kmsg_fd(open("/dev/kmsg_debug", O_WRONLY | O_APPEND | O_CLOEXEC));
if (kmsg_fd.get() >= 0) {
// Our output might contain newlines which would otherwise be handled by the android logger.
// Split the lines up ourselves before sending to the kernel logger.
if (msg.back() == '\n') {
msg.back() = '\0';
}
std::vector<std::string> fragments = android::base::Split(msg, "\n");
for (const std::string& fragment : fragments) {
static constexpr char prefix[] = "<3>DEBUG: ";
struct iovec iov[3];
iov[0].iov_base = const_cast<char*>(prefix);
iov[0].iov_len = strlen(prefix);
iov[1].iov_base = const_cast<char*>(fragment.c_str());
iov[1].iov_len = fragment.length();
iov[2].iov_base = const_cast<char*>("\n");
iov[2].iov_len = 1;
TEMP_FAILURE_RETRY(writev(kmsg_fd.get(), iov, 3));
}
}
}
}
}
#define MEMORY_BYTES_TO_DUMP 256
#define MEMORY_BYTES_PER_LINE 16
void dump_memory(log_t* log, unwindstack::Memory* memory, uint64_t addr, const std::string& label) {
// Align the address to sizeof(long) and start 32 bytes before the address.
addr &= ~(sizeof(long) - 1);
if (addr >= 4128) {
addr -= 32;
}
// Don't bother if the address looks too low, or looks too high.
if (addr < 4096 ||
#if defined(__LP64__)
addr > 0x4000000000000000UL - MEMORY_BYTES_TO_DUMP) {
#else
addr > 0xffff0000 - MEMORY_BYTES_TO_DUMP) {
#endif
return;
}
_LOG(log, logtype::MEMORY, "\n%s:\n", label.c_str());
// Dump 256 bytes
uintptr_t data[MEMORY_BYTES_TO_DUMP/sizeof(uintptr_t)];
memset(data, 0, MEMORY_BYTES_TO_DUMP);
size_t bytes = memory->Read(addr, reinterpret_cast<uint8_t*>(data), sizeof(data));
if (bytes % sizeof(uintptr_t) != 0) {
// This should never happen, but just in case.
ALOGE("Bytes read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
bytes &= ~(sizeof(uintptr_t) - 1);
}
uint64_t start = 0;
bool skip_2nd_read = false;
if (bytes == 0) {
// In this case, we might want to try another read at the beginning of
// the next page only if it's within the amount of memory we would have
// read.
size_t page_size = sysconf(_SC_PAGE_SIZE);
start = ((addr + (page_size - 1)) & ~(page_size - 1)) - addr;
if (start == 0 || start >= MEMORY_BYTES_TO_DUMP) {
skip_2nd_read = true;
}
}
if (bytes < MEMORY_BYTES_TO_DUMP && !skip_2nd_read) {
// Try to do one more read. This could happen if a read crosses a map,
// but the maps do not have any break between them. Or it could happen
// if reading from an unreadable map, but the read would cross back
// into a readable map. Only requires one extra read because a map has
// to contain at least one page, and the total number of bytes to dump
// is smaller than a page.
size_t bytes2 = memory->Read(addr + start + bytes, reinterpret_cast<uint8_t*>(data) + bytes,
sizeof(data) - bytes - start);
bytes += bytes2;
if (bytes2 > 0 && bytes % sizeof(uintptr_t) != 0) {
// This should never happen, but we'll try and continue any way.
ALOGE("Bytes after second read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
bytes &= ~(sizeof(uintptr_t) - 1);
}
}
// Dump the code around memory as:
// addr contents ascii
// 0000000000008d34 ef000000e8bd0090 e1b00000512fff1e ............../Q
// 0000000000008d44 ea00b1f9e92d0090 e3a070fcef000000 ......-..p......
// On 32-bit machines, there are still 16 bytes per line but addresses and
// words are of course presented differently.
uintptr_t* data_ptr = data;
size_t current = 0;
size_t total_bytes = start + bytes;
for (size_t line = 0; line < MEMORY_BYTES_TO_DUMP / MEMORY_BYTES_PER_LINE; line++) {
std::string logline;
android::base::StringAppendF(&logline, " %" PRIPTR, addr);
addr += MEMORY_BYTES_PER_LINE;
std::string ascii;
for (size_t i = 0; i < MEMORY_BYTES_PER_LINE / sizeof(uintptr_t); i++) {
if (current >= start && current + sizeof(uintptr_t) <= total_bytes) {
android::base::StringAppendF(&logline, " %" PRIPTR, static_cast<uint64_t>(*data_ptr));
// Fill out the ascii string from the data.
uint8_t* ptr = reinterpret_cast<uint8_t*>(data_ptr);
for (size_t val = 0; val < sizeof(uintptr_t); val++, ptr++) {
if (*ptr >= 0x20 && *ptr < 0x7f) {
ascii += *ptr;
} else {
ascii += '.';
}
}
data_ptr++;
} else {
logline += ' ' + std::string(sizeof(uintptr_t) * 2, '-');
ascii += std::string(sizeof(uintptr_t), '.');
}
current += sizeof(uintptr_t);
}
_LOG(log, logtype::MEMORY, "%s %s\n", logline.c_str(), ascii.c_str());
}
}
void read_with_default(const char* path, char* buf, size_t len, const char* default_value) {
unique_fd fd(open(path, O_RDONLY | O_CLOEXEC));
if (fd != -1) {
int rc = TEMP_FAILURE_RETRY(read(fd.get(), buf, len - 1));
if (rc != -1) {
buf[rc] = '\0';
// Trim trailing newlines.
if (rc > 0 && buf[rc - 1] == '\n') {
buf[rc - 1] = '\0';
}
return;
}
}
strcpy(buf, default_value);
}
void drop_capabilities() {
__user_cap_header_struct capheader;
memset(&capheader, 0, sizeof(capheader));
capheader.version = _LINUX_CAPABILITY_VERSION_3;
capheader.pid = 0;
__user_cap_data_struct capdata[2];
memset(&capdata, 0, sizeof(capdata));
if (capset(&capheader, &capdata[0]) == -1) {
PLOG(FATAL) << "failed to drop capabilities";
}
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
PLOG(FATAL) << "failed to set PR_SET_NO_NEW_PRIVS";
}
}
bool signal_has_si_addr(int si_signo, int si_code) {
// Manually sent signals won't have si_addr.
if (si_code == SI_USER || si_code == SI_QUEUE || si_code == SI_TKILL) {
return false;
}
switch (si_signo) {
case SIGBUS:
case SIGFPE:
case SIGILL:
case SIGSEGV:
case SIGTRAP:
return true;
default:
return false;
}
}
const char* get_signame(int sig) {
switch (sig) {
case SIGABRT: return "SIGABRT";
case SIGBUS: return "SIGBUS";
case SIGFPE: return "SIGFPE";
case SIGILL: return "SIGILL";
case SIGSEGV: return "SIGSEGV";
#if defined(SIGSTKFLT)
case SIGSTKFLT: return "SIGSTKFLT";
#endif
case SIGSTOP: return "SIGSTOP";
case SIGSYS: return "SIGSYS";
case SIGTRAP: return "SIGTRAP";
case DEBUGGER_SIGNAL: return "<debuggerd signal>";
default: return "?";
}
}
const char* get_sigcode(int signo, int code) {
// Try the signal-specific codes...
switch (signo) {
case SIGILL:
switch (code) {
case ILL_ILLOPC: return "ILL_ILLOPC";
case ILL_ILLOPN: return "ILL_ILLOPN";
case ILL_ILLADR: return "ILL_ILLADR";
case ILL_ILLTRP: return "ILL_ILLTRP";
case ILL_PRVOPC: return "ILL_PRVOPC";
case ILL_PRVREG: return "ILL_PRVREG";
case ILL_COPROC: return "ILL_COPROC";
case ILL_BADSTK: return "ILL_BADSTK";
}
static_assert(NSIGILL == ILL_BADSTK, "missing ILL_* si_code");
break;
case SIGBUS:
switch (code) {
case BUS_ADRALN: return "BUS_ADRALN";
case BUS_ADRERR: return "BUS_ADRERR";
case BUS_OBJERR: return "BUS_OBJERR";
case BUS_MCEERR_AR: return "BUS_MCEERR_AR";
case BUS_MCEERR_AO: return "BUS_MCEERR_AO";
}
static_assert(NSIGBUS == BUS_MCEERR_AO, "missing BUS_* si_code");
break;
case SIGFPE:
switch (code) {
case FPE_INTDIV: return "FPE_INTDIV";
case FPE_INTOVF: return "FPE_INTOVF";
case FPE_FLTDIV: return "FPE_FLTDIV";
case FPE_FLTOVF: return "FPE_FLTOVF";
case FPE_FLTUND: return "FPE_FLTUND";
case FPE_FLTRES: return "FPE_FLTRES";
case FPE_FLTINV: return "FPE_FLTINV";
case FPE_FLTSUB: return "FPE_FLTSUB";
}
static_assert(NSIGFPE == FPE_FLTSUB, "missing FPE_* si_code");
break;
case SIGSEGV:
switch (code) {
case SEGV_MAPERR: return "SEGV_MAPERR";
case SEGV_ACCERR: return "SEGV_ACCERR";
#if defined(SEGV_BNDERR)
case SEGV_BNDERR: return "SEGV_BNDERR";
#endif
#if defined(SEGV_PKUERR)
case SEGV_PKUERR: return "SEGV_PKUERR";
#endif
}
#if defined(SEGV_PKUERR)
static_assert(NSIGSEGV == SEGV_PKUERR, "missing SEGV_* si_code");
#elif defined(SEGV_BNDERR)
static_assert(NSIGSEGV == SEGV_BNDERR, "missing SEGV_* si_code");
#else
static_assert(NSIGSEGV == SEGV_ACCERR, "missing SEGV_* si_code");
#endif
break;
#if defined(SYS_SECCOMP) // Our glibc is too old, and we build this for the host too.
case SIGSYS:
switch (code) {
case SYS_SECCOMP: return "SYS_SECCOMP";
}
static_assert(NSIGSYS == SYS_SECCOMP, "missing SYS_* si_code");
break;
#endif
case SIGTRAP:
switch (code) {
case TRAP_BRKPT: return "TRAP_BRKPT";
case TRAP_TRACE: return "TRAP_TRACE";
case TRAP_BRANCH: return "TRAP_BRANCH";
case TRAP_HWBKPT: return "TRAP_HWBKPT";
}
if ((code & 0xff) == SIGTRAP) {
switch ((code >> 8) & 0xff) {
case PTRACE_EVENT_FORK:
return "PTRACE_EVENT_FORK";
case PTRACE_EVENT_VFORK:
return "PTRACE_EVENT_VFORK";
case PTRACE_EVENT_CLONE:
return "PTRACE_EVENT_CLONE";
case PTRACE_EVENT_EXEC:
return "PTRACE_EVENT_EXEC";
case PTRACE_EVENT_VFORK_DONE:
return "PTRACE_EVENT_VFORK_DONE";
case PTRACE_EVENT_EXIT:
return "PTRACE_EVENT_EXIT";
case PTRACE_EVENT_SECCOMP:
return "PTRACE_EVENT_SECCOMP";
case PTRACE_EVENT_STOP:
return "PTRACE_EVENT_STOP";
}
}
static_assert(NSIGTRAP == TRAP_HWBKPT, "missing TRAP_* si_code");
break;
}
// Then the other codes...
switch (code) {
case SI_USER: return "SI_USER";
case SI_KERNEL: return "SI_KERNEL";
case SI_QUEUE: return "SI_QUEUE";
case SI_TIMER: return "SI_TIMER";
case SI_MESGQ: return "SI_MESGQ";
case SI_ASYNCIO: return "SI_ASYNCIO";
case SI_SIGIO: return "SI_SIGIO";
case SI_TKILL: return "SI_TKILL";
case SI_DETHREAD: return "SI_DETHREAD";
}
// Then give up...
return "?";
}
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