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platform_system_core/debuggerd/libdebuggerd/utility.cpp
Christopher Ferris c95047dd20 Update for accurate unreadable elf files. 
The functionality moved from the Unwinder object to the MapInfo
object and means that the individual unreadable files can be
displayed now.

Included adding the unreadable elfs per thread in the protobuf.

Updated the unwinder test.

Test: All unit tests pass.
Change-Id: I7140bde16938736da005f926e10bbdb3dbc0f6f5
2022-03-15 09:50:48 -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 <set>
#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 "?";
}
#define DESCRIBE_FLAG(flag) \
if (value & flag) { \
desc += ", "; \
desc += #flag; \
value &= ~flag; \
}
static std::string describe_end(long value, std::string& desc) {
if (value) {
desc += StringPrintf(", unknown 0x%lx", value);
}
return desc.empty() ? "" : " (" + desc.substr(2) + ")";
}
std::string describe_tagged_addr_ctrl(long value) {
std::string desc;
DESCRIBE_FLAG(PR_TAGGED_ADDR_ENABLE);
DESCRIBE_FLAG(PR_MTE_TCF_SYNC);
DESCRIBE_FLAG(PR_MTE_TCF_ASYNC);
if (value & PR_MTE_TAG_MASK) {
desc += StringPrintf(", mask 0x%04lx", (value & PR_MTE_TAG_MASK) >> PR_MTE_TAG_SHIFT);
value &= ~PR_MTE_TAG_MASK;
}
return describe_end(value, desc);
}
std::string describe_pac_enabled_keys(long value) {
std::string desc;
DESCRIBE_FLAG(PR_PAC_APIAKEY);
DESCRIBE_FLAG(PR_PAC_APIBKEY);
DESCRIBE_FLAG(PR_PAC_APDAKEY);
DESCRIBE_FLAG(PR_PAC_APDBKEY);
DESCRIBE_FLAG(PR_PAC_APGAKEY);
return describe_end(value, desc);
}
void log_backtrace(log_t* log, unwindstack::Unwinder* unwinder, const char* prefix) {
std::set<std::string> unreadable_elf_files;
unwinder->SetDisplayBuildID(true);
for (const auto& frame : unwinder->frames()) {
if (frame.map_info != nullptr && frame.map_info->ElfFileNotReadable()) {
unreadable_elf_files.emplace(frame.map_info->name());
}
}
// Put the preamble ahead of the backtrace.
if (!unreadable_elf_files.empty()) {
_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
_LOG(log, logtype::BACKTRACE, "%sNOTE: Unreadable libraries:\n", prefix);
for (auto& name : unreadable_elf_files) {
_LOG(log, logtype::BACKTRACE, "%sNOTE: %s\n", prefix, name.c_str());
}
}
for (const auto& frame : unwinder->frames()) {
_LOG(log, logtype::BACKTRACE, "%s%s\n", prefix, unwinder->FormatFrame(frame).c_str());
}
}
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