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platform_system_core/debuggerd/libdebuggerd/utility.cpp
Treehugger Robot a44f269eba Merge "Improvements to tombstone output."
2021-11-12 00:17:12 +00:00

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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/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <async_safe/log.h>
#include <bionic/reserved_signals.h>
#include <debuggerd/handler.h>
#include <log/log.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Unwinder.h>
using android::base::StringPrintf;
using android::base::unique_fd;
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, ...) {
va_list ap;
va_start(ap, fmt);
_VLOG(log, ltype, fmt, ap);
va_end(ap);
}
__attribute__((__weak__, visibility("default")))
void _VLOG(log_t* log, enum logtype ltype, const char* fmt, va_list ap) {
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;
android::base::StringAppendV(&msg, fmt, 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
static_assert(MEMORY_BYTES_PER_LINE == kTagGranuleSize);
ssize_t dump_memory(void* out, size_t len, uint8_t* tags, size_t tags_len, uint64_t* addr,
unwindstack::Memory* memory) {
// Align the address to the number of bytes per line to avoid confusing memory tag output if
// memory is tagged and we start from a misaligned address. Start 32 bytes before the address.
*addr &= ~(MEMORY_BYTES_PER_LINE - 1);
if (*addr >= 4128) {
*addr -= 32;
}
// We don't want the address tag to appear in the addresses in the memory dump.
*addr = untag_address(*addr);
// Don't bother if the address would overflow, taking tag bits into account. Note that
// untag_address truncates to 32 bits on 32-bit platforms as a side effect of returning a
// uintptr_t, so this also checks for 32-bit overflow.
if (untag_address(*addr + MEMORY_BYTES_TO_DUMP - 1) < *addr) {
return -1;
}
memset(out, 0, len);
size_t bytes = memory->Read(*addr, reinterpret_cast<uint8_t*>(out), len);
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);
}
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);
uint64_t next_page = (*addr + (page_size - 1)) & ~(page_size - 1);
if (next_page == *addr || next_page >= *addr + len) {
skip_2nd_read = true;
}
*addr = next_page;
}
if (bytes < len && !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 + bytes, static_cast<uint8_t*>(out) + bytes, len - bytes);
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);
}
}
// If we were unable to read anything, it probably means that the register doesn't contain a
// valid pointer.
if (bytes == 0) {
return -1;
}
for (uint64_t tag_granule = 0; tag_granule < bytes / kTagGranuleSize; ++tag_granule) {
long tag = memory->ReadTag(*addr + kTagGranuleSize * tag_granule);
if (tag_granule < tags_len) {
tags[tag_granule] = tag >= 0 ? tag : 0;
} else {
ALOGE("Insufficient space for tags");
}
}
return bytes;
}
void dump_memory(log_t* log, unwindstack::Memory* memory, uint64_t addr, const std::string& label) {
// Dump 256 bytes
uintptr_t data[MEMORY_BYTES_TO_DUMP / sizeof(uintptr_t)];
uint8_t tags[MEMORY_BYTES_TO_DUMP / kTagGranuleSize];
ssize_t bytes = dump_memory(data, sizeof(data), tags, sizeof(tags), &addr, memory);
if (bytes == -1) {
return;
}
_LOG(log, logtype::MEMORY, "\n%s:\n", label.c_str());
// 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;
uint8_t* tags_ptr = tags;
for (size_t line = 0; line < static_cast<size_t>(bytes) / MEMORY_BYTES_PER_LINE; line++) {
uint64_t tagged_addr = addr | static_cast<uint64_t>(*tags_ptr++) << 56;
std::string logline;
android::base::StringAppendF(&logline, " %" PRIPTR, tagged_addr);
addr += MEMORY_BYTES_PER_LINE;
std::string ascii;
for (size_t i = 0; i < MEMORY_BYTES_PER_LINE / sizeof(uintptr_t); i++) {
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++;
}
_LOG(log, logtype::MEMORY, "%s %s\n", logline.c_str(), ascii.c_str());
}
}
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) {
async_safe_fatal("failed to drop capabilities: %s", strerror(errno));
}
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
async_safe_fatal("failed to set PR_SET_NO_NEW_PRIVS: %s", strerror(errno));
}
}
bool signal_has_si_addr(const siginfo_t* si) {
// Manually sent signals won't have si_addr.
if (si->si_code == SI_USER || si->si_code == SI_QUEUE || si->si_code == SI_TKILL) {
return false;
}
switch (si->si_signo) {
case SIGBUS:
case SIGFPE:
case SIGILL:
case SIGTRAP:
return true;
case SIGSEGV:
return si->si_code != SEGV_MTEAERR;
default:
return false;
}
}
bool signal_has_sender(const siginfo_t* si, pid_t caller_pid) {
return SI_FROMUSER(si) && (si->si_pid != 0) && (si->si_pid != caller_pid);
}
void get_signal_sender(char* buf, size_t n, const siginfo_t* si) {
snprintf(buf, n, " from pid %d, uid %d", si->si_pid, si->si_uid);
}
const char* get_signame(const siginfo_t* si) {
switch (si->si_signo) {
case SIGABRT: return "SIGABRT";
case SIGBUS: return "SIGBUS";
case SIGFPE: return "SIGFPE";
case SIGILL: return "SIGILL";
case SIGSEGV: return "SIGSEGV";
case SIGSTKFLT: return "SIGSTKFLT";
case SIGSTOP: return "SIGSTOP";
case SIGSYS: return "SIGSYS";
case SIGTRAP: return "SIGTRAP";
case BIONIC_SIGNAL_DEBUGGER:
return "<debuggerd signal>";
default: return "?";
}
}
const char* get_sigcode(const siginfo_t* si) {
// Try the signal-specific codes...
switch (si->si_signo) {
case SIGILL:
switch (si->si_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";
case ILL_BADIADDR:
return "ILL_BADIADDR";
case __ILL_BREAK:
return "ILL_BREAK";
case __ILL_BNDMOD:
return "ILL_BNDMOD";
}
static_assert(NSIGILL == __ILL_BNDMOD, "missing ILL_* si_code");
break;
case SIGBUS:
switch (si->si_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 (si->si_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";
case __FPE_DECOVF:
return "FPE_DECOVF";
case __FPE_DECDIV:
return "FPE_DECDIV";
case __FPE_DECERR:
return "FPE_DECERR";
case __FPE_INVASC:
return "FPE_INVASC";
case __FPE_INVDEC:
return "FPE_INVDEC";
case FPE_FLTUNK:
return "FPE_FLTUNK";
case FPE_CONDTRAP:
return "FPE_CONDTRAP";
}
static_assert(NSIGFPE == FPE_CONDTRAP, "missing FPE_* si_code");
break;
case SIGSEGV:
switch (si->si_code) {
case SEGV_MAPERR: return "SEGV_MAPERR";
case SEGV_ACCERR: return "SEGV_ACCERR";
case SEGV_BNDERR: return "SEGV_BNDERR";
case SEGV_PKUERR: return "SEGV_PKUERR";
case SEGV_ACCADI:
return "SEGV_ACCADI";
case SEGV_ADIDERR:
return "SEGV_ADIDERR";
case SEGV_ADIPERR:
return "SEGV_ADIPERR";
case SEGV_MTEAERR:
return "SEGV_MTEAERR";
case SEGV_MTESERR:
return "SEGV_MTESERR";
}
static_assert(NSIGSEGV == SEGV_MTESERR, "missing SEGV_* si_code");
break;
case SIGSYS:
switch (si->si_code) {
case SYS_SECCOMP: return "SYS_SECCOMP";
case SYS_USER_DISPATCH:
return "SYS_USER_DISPATCH";
}
static_assert(NSIGSYS == SYS_USER_DISPATCH, "missing SYS_* si_code");
break;
case SIGTRAP:
switch (si->si_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";
case TRAP_UNK:
return "TRAP_UNDIAGNOSED";
case TRAP_PERF:
return "TRAP_PERF";
}
if ((si->si_code & 0xff) == SIGTRAP) {
switch ((si->si_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_PERF, "missing TRAP_* si_code");
break;
}
// Then the other codes...
switch (si->si_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 "?";
}
std::string describe_tagged_addr_ctrl(long ctrl) {
std::string desc;
if (ctrl & PR_TAGGED_ADDR_ENABLE) {
desc += ", PR_TAGGED_ADDR_ENABLE";
ctrl &= ~PR_TAGGED_ADDR_ENABLE;
}
if (ctrl & PR_MTE_TCF_SYNC) {
desc += ", PR_MTE_TCF_SYNC";
ctrl &= ~PR_MTE_TCF_SYNC;
}
if (ctrl & PR_MTE_TCF_ASYNC) {
desc += ", PR_MTE_TCF_ASYNC";
ctrl &= ~PR_MTE_TCF_ASYNC;
}
if (ctrl & PR_MTE_TAG_MASK) {
desc += StringPrintf(", mask 0x%04lx", (ctrl & PR_MTE_TAG_MASK) >> PR_MTE_TAG_SHIFT);
ctrl &= ~PR_MTE_TAG_MASK;
}
if (ctrl) {
desc += StringPrintf(", unknown 0x%lx", ctrl);
}
if (desc.empty()) {
return "";
}
return " (" + desc.substr(2) + ")";
}
void log_backtrace(log_t* log, unwindstack::Unwinder* unwinder, const char* prefix) {
if (unwinder->elf_from_memory_not_file()) {
_LOG(log, logtype::BACKTRACE,
"%sNOTE: Function names and BuildId information is missing for some frames due\n", prefix);
_LOG(log, logtype::BACKTRACE,
"%sNOTE: to unreadable libraries. For unwinds of apps, only shared libraries\n", prefix);
_LOG(log, logtype::BACKTRACE, "%sNOTE: found under the lib/ directory are readable.\n", prefix);
#if defined(ROOT_POSSIBLE)
_LOG(log, logtype::BACKTRACE,
"%sNOTE: On this device, run setenforce 0 to make the libraries readable.\n", prefix);
#endif
}
unwinder->SetDisplayBuildID(true);
for (size_t i = 0; i < unwinder->NumFrames(); i++) {
_LOG(log, logtype::BACKTRACE, "%s%s\n", prefix, unwinder->FormatFrame(i).c_str());
}
}
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