1 /*
2 * Copyright 2008, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define LOG_TAG "DEBUG"
18
19 #include "libdebuggerd/utility.h"
20
21 #include <errno.h>
22 #include <signal.h>
23 #include <string.h>
24 #include <sys/capability.h>
25 #include <sys/prctl.h>
26 #include <sys/ptrace.h>
27 #include <sys/uio.h>
28 #include <sys/wait.h>
29 #include <unistd.h>
30
31 #include <set>
32 #include <string>
33
34 #include <android-base/properties.h>
35 #include <android-base/stringprintf.h>
36 #include <android-base/strings.h>
37 #include <android-base/unique_fd.h>
38 #include <async_safe/log.h>
39 #include <bionic/reserved_signals.h>
40 #include <debuggerd/handler.h>
41 #include <log/log.h>
42 #include <unwindstack/Memory.h>
43 #include <unwindstack/Unwinder.h>
44
45 using android::base::StringPrintf;
46 using android::base::unique_fd;
47
is_allowed_in_logcat(enum logtype ltype)48 bool is_allowed_in_logcat(enum logtype ltype) {
49 if ((ltype == HEADER)
50 || (ltype == REGISTERS)
51 || (ltype == BACKTRACE)) {
52 return true;
53 }
54 return false;
55 }
56
should_write_to_kmsg()57 static bool should_write_to_kmsg() {
58 // Write to kmsg if tombstoned isn't up, and we're able to do so.
59 if (!android::base::GetBoolProperty("ro.debuggable", false)) {
60 return false;
61 }
62
63 if (android::base::GetProperty("init.svc.tombstoned", "") == "running") {
64 return false;
65 }
66
67 return true;
68 }
69
70 __attribute__((__weak__, visibility("default")))
_LOG(log_t * log,enum logtype ltype,const char * fmt,...)71 void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) {
72 va_list ap;
73 va_start(ap, fmt);
74 _VLOG(log, ltype, fmt, ap);
75 va_end(ap);
76 }
77
78 __attribute__((__weak__, visibility("default")))
_VLOG(log_t * log,enum logtype ltype,const char * fmt,va_list ap)79 void _VLOG(log_t* log, enum logtype ltype, const char* fmt, va_list ap) {
80 bool write_to_tombstone = (log->tfd != -1);
81 bool write_to_logcat = is_allowed_in_logcat(ltype)
82 && log->crashed_tid != -1
83 && log->current_tid != -1
84 && (log->crashed_tid == log->current_tid);
85 static bool write_to_kmsg = should_write_to_kmsg();
86
87 std::string msg;
88 android::base::StringAppendV(&msg, fmt, ap);
89
90 if (msg.empty()) return;
91
92 if (write_to_tombstone) {
93 TEMP_FAILURE_RETRY(write(log->tfd, msg.c_str(), msg.size()));
94 }
95
96 if (write_to_logcat) {
97 __android_log_buf_write(LOG_ID_CRASH, ANDROID_LOG_FATAL, LOG_TAG, msg.c_str());
98 if (log->amfd_data != nullptr) {
99 *log->amfd_data += msg;
100 }
101
102 if (write_to_kmsg) {
103 unique_fd kmsg_fd(open("/dev/kmsg_debug", O_WRONLY | O_APPEND | O_CLOEXEC));
104 if (kmsg_fd.get() >= 0) {
105 // Our output might contain newlines which would otherwise be handled by the android logger.
106 // Split the lines up ourselves before sending to the kernel logger.
107 if (msg.back() == '\n') {
108 msg.back() = '\0';
109 }
110
111 std::vector<std::string> fragments = android::base::Split(msg, "\n");
112 for (const std::string& fragment : fragments) {
113 static constexpr char prefix[] = "<3>DEBUG: ";
114 struct iovec iov[3];
115 iov[0].iov_base = const_cast<char*>(prefix);
116 iov[0].iov_len = strlen(prefix);
117 iov[1].iov_base = const_cast<char*>(fragment.c_str());
118 iov[1].iov_len = fragment.length();
119 iov[2].iov_base = const_cast<char*>("\n");
120 iov[2].iov_len = 1;
121 TEMP_FAILURE_RETRY(writev(kmsg_fd.get(), iov, 3));
122 }
123 }
124 }
125 }
126 }
127
128 #define MEMORY_BYTES_TO_DUMP 256
129 #define MEMORY_BYTES_PER_LINE 16
130 static_assert(MEMORY_BYTES_PER_LINE == kTagGranuleSize);
131
dump_memory(void * out,size_t len,uint8_t * tags,size_t tags_len,uint64_t * addr,unwindstack::Memory * memory)132 ssize_t dump_memory(void* out, size_t len, uint8_t* tags, size_t tags_len, uint64_t* addr,
133 unwindstack::Memory* memory) {
134 // Align the address to the number of bytes per line to avoid confusing memory tag output if
135 // memory is tagged and we start from a misaligned address. Start 32 bytes before the address.
136 *addr &= ~(MEMORY_BYTES_PER_LINE - 1);
137 if (*addr >= 4128) {
138 *addr -= 32;
139 }
140
141 // We don't want the address tag to appear in the addresses in the memory dump.
142 *addr = untag_address(*addr);
143
144 // Don't bother if the address would overflow, taking tag bits into account. Note that
145 // untag_address truncates to 32 bits on 32-bit platforms as a side effect of returning a
146 // uintptr_t, so this also checks for 32-bit overflow.
147 if (untag_address(*addr + MEMORY_BYTES_TO_DUMP - 1) < *addr) {
148 return -1;
149 }
150
151 memset(out, 0, len);
152
153 size_t bytes = memory->Read(*addr, reinterpret_cast<uint8_t*>(out), len);
154 if (bytes % sizeof(uintptr_t) != 0) {
155 // This should never happen, but just in case.
156 ALOGE("Bytes read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
157 bytes &= ~(sizeof(uintptr_t) - 1);
158 }
159
160 bool skip_2nd_read = false;
161 if (bytes == 0) {
162 // In this case, we might want to try another read at the beginning of
163 // the next page only if it's within the amount of memory we would have
164 // read.
165 size_t page_size = sysconf(_SC_PAGE_SIZE);
166 uint64_t next_page = (*addr + (page_size - 1)) & ~(page_size - 1);
167 if (next_page == *addr || next_page >= *addr + len) {
168 skip_2nd_read = true;
169 }
170 *addr = next_page;
171 }
172
173 if (bytes < len && !skip_2nd_read) {
174 // Try to do one more read. This could happen if a read crosses a map,
175 // but the maps do not have any break between them. Or it could happen
176 // if reading from an unreadable map, but the read would cross back
177 // into a readable map. Only requires one extra read because a map has
178 // to contain at least one page, and the total number of bytes to dump
179 // is smaller than a page.
180 size_t bytes2 = memory->Read(*addr + bytes, static_cast<uint8_t*>(out) + bytes, len - bytes);
181 bytes += bytes2;
182 if (bytes2 > 0 && bytes % sizeof(uintptr_t) != 0) {
183 // This should never happen, but we'll try and continue any way.
184 ALOGE("Bytes after second read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
185 bytes &= ~(sizeof(uintptr_t) - 1);
186 }
187 }
188
189 // If we were unable to read anything, it probably means that the register doesn't contain a
190 // valid pointer.
191 if (bytes == 0) {
192 return -1;
193 }
194
195 for (uint64_t tag_granule = 0; tag_granule < bytes / kTagGranuleSize; ++tag_granule) {
196 long tag = memory->ReadTag(*addr + kTagGranuleSize * tag_granule);
197 if (tag_granule < tags_len) {
198 tags[tag_granule] = tag >= 0 ? tag : 0;
199 } else {
200 ALOGE("Insufficient space for tags");
201 }
202 }
203
204 return bytes;
205 }
206
dump_memory(log_t * log,unwindstack::Memory * memory,uint64_t addr,const std::string & label)207 void dump_memory(log_t* log, unwindstack::Memory* memory, uint64_t addr, const std::string& label) {
208 // Dump 256 bytes
209 uintptr_t data[MEMORY_BYTES_TO_DUMP / sizeof(uintptr_t)];
210 uint8_t tags[MEMORY_BYTES_TO_DUMP / kTagGranuleSize];
211
212 ssize_t bytes = dump_memory(data, sizeof(data), tags, sizeof(tags), &addr, memory);
213 if (bytes == -1) {
214 return;
215 }
216
217 _LOG(log, logtype::MEMORY, "\n%s:\n", label.c_str());
218
219 // Dump the code around memory as:
220 // addr contents ascii
221 // 0000000000008d34 ef000000e8bd0090 e1b00000512fff1e ............../Q
222 // 0000000000008d44 ea00b1f9e92d0090 e3a070fcef000000 ......-..p......
223 // On 32-bit machines, there are still 16 bytes per line but addresses and
224 // words are of course presented differently.
225 uintptr_t* data_ptr = data;
226 uint8_t* tags_ptr = tags;
227 for (size_t line = 0; line < static_cast<size_t>(bytes) / MEMORY_BYTES_PER_LINE; line++) {
228 uint64_t tagged_addr = addr | static_cast<uint64_t>(*tags_ptr++) << 56;
229 std::string logline;
230 android::base::StringAppendF(&logline, " %" PRIPTR, tagged_addr);
231
232 addr += MEMORY_BYTES_PER_LINE;
233 std::string ascii;
234 for (size_t i = 0; i < MEMORY_BYTES_PER_LINE / sizeof(uintptr_t); i++) {
235 android::base::StringAppendF(&logline, " %" PRIPTR, static_cast<uint64_t>(*data_ptr));
236
237 // Fill out the ascii string from the data.
238 uint8_t* ptr = reinterpret_cast<uint8_t*>(data_ptr);
239 for (size_t val = 0; val < sizeof(uintptr_t); val++, ptr++) {
240 if (*ptr >= 0x20 && *ptr < 0x7f) {
241 ascii += *ptr;
242 } else {
243 ascii += '.';
244 }
245 }
246 data_ptr++;
247 }
248 _LOG(log, logtype::MEMORY, "%s %s\n", logline.c_str(), ascii.c_str());
249 }
250 }
251
drop_capabilities()252 void drop_capabilities() {
253 __user_cap_header_struct capheader;
254 memset(&capheader, 0, sizeof(capheader));
255 capheader.version = _LINUX_CAPABILITY_VERSION_3;
256 capheader.pid = 0;
257
258 __user_cap_data_struct capdata[2];
259 memset(&capdata, 0, sizeof(capdata));
260
261 if (capset(&capheader, &capdata[0]) == -1) {
262 async_safe_fatal("failed to drop capabilities: %s", strerror(errno));
263 }
264
265 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
266 async_safe_fatal("failed to set PR_SET_NO_NEW_PRIVS: %s", strerror(errno));
267 }
268 }
269
signal_has_si_addr(const siginfo_t * si)270 bool signal_has_si_addr(const siginfo_t* si) {
271 // Manually sent signals won't have si_addr.
272 if (si->si_code == SI_USER || si->si_code == SI_QUEUE || si->si_code == SI_TKILL) {
273 return false;
274 }
275
276 switch (si->si_signo) {
277 case SIGBUS:
278 case SIGFPE:
279 case SIGILL:
280 case SIGTRAP:
281 return true;
282 case SIGSEGV:
283 return si->si_code != SEGV_MTEAERR;
284 default:
285 return false;
286 }
287 }
288
signal_has_sender(const siginfo_t * si,pid_t caller_pid)289 bool signal_has_sender(const siginfo_t* si, pid_t caller_pid) {
290 return SI_FROMUSER(si) && (si->si_pid != 0) && (si->si_pid != caller_pid);
291 }
292
get_signal_sender(char * buf,size_t n,const siginfo_t * si)293 void get_signal_sender(char* buf, size_t n, const siginfo_t* si) {
294 snprintf(buf, n, " from pid %d, uid %d", si->si_pid, si->si_uid);
295 }
296
get_signame(const siginfo_t * si)297 const char* get_signame(const siginfo_t* si) {
298 switch (si->si_signo) {
299 case SIGABRT: return "SIGABRT";
300 case SIGBUS: return "SIGBUS";
301 case SIGFPE: return "SIGFPE";
302 case SIGILL: return "SIGILL";
303 case SIGSEGV: return "SIGSEGV";
304 case SIGSTKFLT: return "SIGSTKFLT";
305 case SIGSTOP: return "SIGSTOP";
306 case SIGSYS: return "SIGSYS";
307 case SIGTRAP: return "SIGTRAP";
308 case BIONIC_SIGNAL_DEBUGGER:
309 return "<debuggerd signal>";
310 default: return "?";
311 }
312 }
313
get_sigcode(const siginfo_t * si)314 const char* get_sigcode(const siginfo_t* si) {
315 // Try the signal-specific codes...
316 switch (si->si_signo) {
317 case SIGILL:
318 switch (si->si_code) {
319 case ILL_ILLOPC: return "ILL_ILLOPC";
320 case ILL_ILLOPN: return "ILL_ILLOPN";
321 case ILL_ILLADR: return "ILL_ILLADR";
322 case ILL_ILLTRP: return "ILL_ILLTRP";
323 case ILL_PRVOPC: return "ILL_PRVOPC";
324 case ILL_PRVREG: return "ILL_PRVREG";
325 case ILL_COPROC: return "ILL_COPROC";
326 case ILL_BADSTK: return "ILL_BADSTK";
327 case ILL_BADIADDR:
328 return "ILL_BADIADDR";
329 case __ILL_BREAK:
330 return "ILL_BREAK";
331 case __ILL_BNDMOD:
332 return "ILL_BNDMOD";
333 }
334 static_assert(NSIGILL == __ILL_BNDMOD, "missing ILL_* si_code");
335 break;
336 case SIGBUS:
337 switch (si->si_code) {
338 case BUS_ADRALN: return "BUS_ADRALN";
339 case BUS_ADRERR: return "BUS_ADRERR";
340 case BUS_OBJERR: return "BUS_OBJERR";
341 case BUS_MCEERR_AR: return "BUS_MCEERR_AR";
342 case BUS_MCEERR_AO: return "BUS_MCEERR_AO";
343 }
344 static_assert(NSIGBUS == BUS_MCEERR_AO, "missing BUS_* si_code");
345 break;
346 case SIGFPE:
347 switch (si->si_code) {
348 case FPE_INTDIV: return "FPE_INTDIV";
349 case FPE_INTOVF: return "FPE_INTOVF";
350 case FPE_FLTDIV: return "FPE_FLTDIV";
351 case FPE_FLTOVF: return "FPE_FLTOVF";
352 case FPE_FLTUND: return "FPE_FLTUND";
353 case FPE_FLTRES: return "FPE_FLTRES";
354 case FPE_FLTINV: return "FPE_FLTINV";
355 case FPE_FLTSUB: return "FPE_FLTSUB";
356 case __FPE_DECOVF:
357 return "FPE_DECOVF";
358 case __FPE_DECDIV:
359 return "FPE_DECDIV";
360 case __FPE_DECERR:
361 return "FPE_DECERR";
362 case __FPE_INVASC:
363 return "FPE_INVASC";
364 case __FPE_INVDEC:
365 return "FPE_INVDEC";
366 case FPE_FLTUNK:
367 return "FPE_FLTUNK";
368 case FPE_CONDTRAP:
369 return "FPE_CONDTRAP";
370 }
371 static_assert(NSIGFPE == FPE_CONDTRAP, "missing FPE_* si_code");
372 break;
373 case SIGSEGV:
374 switch (si->si_code) {
375 case SEGV_MAPERR: return "SEGV_MAPERR";
376 case SEGV_ACCERR: return "SEGV_ACCERR";
377 case SEGV_BNDERR: return "SEGV_BNDERR";
378 case SEGV_PKUERR: return "SEGV_PKUERR";
379 case SEGV_ACCADI:
380 return "SEGV_ACCADI";
381 case SEGV_ADIDERR:
382 return "SEGV_ADIDERR";
383 case SEGV_ADIPERR:
384 return "SEGV_ADIPERR";
385 case SEGV_MTEAERR:
386 return "SEGV_MTEAERR";
387 case SEGV_MTESERR:
388 return "SEGV_MTESERR";
389 }
390 static_assert(NSIGSEGV == SEGV_MTESERR, "missing SEGV_* si_code");
391 break;
392 case SIGSYS:
393 switch (si->si_code) {
394 case SYS_SECCOMP: return "SYS_SECCOMP";
395 case SYS_USER_DISPATCH:
396 return "SYS_USER_DISPATCH";
397 }
398 static_assert(NSIGSYS == SYS_USER_DISPATCH, "missing SYS_* si_code");
399 break;
400 case SIGTRAP:
401 switch (si->si_code) {
402 case TRAP_BRKPT: return "TRAP_BRKPT";
403 case TRAP_TRACE: return "TRAP_TRACE";
404 case TRAP_BRANCH: return "TRAP_BRANCH";
405 case TRAP_HWBKPT: return "TRAP_HWBKPT";
406 case TRAP_UNK:
407 return "TRAP_UNDIAGNOSED";
408 case TRAP_PERF:
409 return "TRAP_PERF";
410 }
411 if ((si->si_code & 0xff) == SIGTRAP) {
412 switch ((si->si_code >> 8) & 0xff) {
413 case PTRACE_EVENT_FORK:
414 return "PTRACE_EVENT_FORK";
415 case PTRACE_EVENT_VFORK:
416 return "PTRACE_EVENT_VFORK";
417 case PTRACE_EVENT_CLONE:
418 return "PTRACE_EVENT_CLONE";
419 case PTRACE_EVENT_EXEC:
420 return "PTRACE_EVENT_EXEC";
421 case PTRACE_EVENT_VFORK_DONE:
422 return "PTRACE_EVENT_VFORK_DONE";
423 case PTRACE_EVENT_EXIT:
424 return "PTRACE_EVENT_EXIT";
425 case PTRACE_EVENT_SECCOMP:
426 return "PTRACE_EVENT_SECCOMP";
427 case PTRACE_EVENT_STOP:
428 return "PTRACE_EVENT_STOP";
429 }
430 }
431 static_assert(NSIGTRAP == TRAP_PERF, "missing TRAP_* si_code");
432 break;
433 }
434 // Then the other codes...
435 switch (si->si_code) {
436 case SI_USER: return "SI_USER";
437 case SI_KERNEL: return "SI_KERNEL";
438 case SI_QUEUE: return "SI_QUEUE";
439 case SI_TIMER: return "SI_TIMER";
440 case SI_MESGQ: return "SI_MESGQ";
441 case SI_ASYNCIO: return "SI_ASYNCIO";
442 case SI_SIGIO: return "SI_SIGIO";
443 case SI_TKILL: return "SI_TKILL";
444 case SI_DETHREAD: return "SI_DETHREAD";
445 }
446 // Then give up...
447 return "?";
448 }
449
450 #define DESCRIBE_FLAG(flag) \
451 if (value & flag) { \
452 desc += ", "; \
453 desc += #flag; \
454 value &= ~flag; \
455 }
456
describe_end(long value,std::string & desc)457 static std::string describe_end(long value, std::string& desc) {
458 if (value) {
459 desc += StringPrintf(", unknown 0x%lx", value);
460 }
461 return desc.empty() ? "" : " (" + desc.substr(2) + ")";
462 }
463
describe_tagged_addr_ctrl(long value)464 std::string describe_tagged_addr_ctrl(long value) {
465 std::string desc;
466 DESCRIBE_FLAG(PR_TAGGED_ADDR_ENABLE);
467 DESCRIBE_FLAG(PR_MTE_TCF_SYNC);
468 DESCRIBE_FLAG(PR_MTE_TCF_ASYNC);
469 if (value & PR_MTE_TAG_MASK) {
470 desc += StringPrintf(", mask 0x%04lx", (value & PR_MTE_TAG_MASK) >> PR_MTE_TAG_SHIFT);
471 value &= ~PR_MTE_TAG_MASK;
472 }
473 return describe_end(value, desc);
474 }
475
describe_pac_enabled_keys(long value)476 std::string describe_pac_enabled_keys(long value) {
477 std::string desc;
478 DESCRIBE_FLAG(PR_PAC_APIAKEY);
479 DESCRIBE_FLAG(PR_PAC_APIBKEY);
480 DESCRIBE_FLAG(PR_PAC_APDAKEY);
481 DESCRIBE_FLAG(PR_PAC_APDBKEY);
482 DESCRIBE_FLAG(PR_PAC_APGAKEY);
483 return describe_end(value, desc);
484 }
485
log_backtrace(log_t * log,unwindstack::Unwinder * unwinder,const char * prefix)486 void log_backtrace(log_t* log, unwindstack::Unwinder* unwinder, const char* prefix) {
487 std::set<std::string> unreadable_elf_files;
488 unwinder->SetDisplayBuildID(true);
489 for (const auto& frame : unwinder->frames()) {
490 if (frame.map_info != nullptr && frame.map_info->ElfFileNotReadable()) {
491 unreadable_elf_files.emplace(frame.map_info->name());
492 }
493 }
494
495 // Put the preamble ahead of the backtrace.
496 if (!unreadable_elf_files.empty()) {
497 _LOG(log, logtype::BACKTRACE,
498 "%sNOTE: Function names and BuildId information is missing for some frames due\n", prefix);
499 _LOG(log, logtype::BACKTRACE,
500 "%sNOTE: to unreadable libraries. For unwinds of apps, only shared libraries\n", prefix);
501 _LOG(log, logtype::BACKTRACE, "%sNOTE: found under the lib/ directory are readable.\n", prefix);
502 #if defined(ROOT_POSSIBLE)
503 _LOG(log, logtype::BACKTRACE,
504 "%sNOTE: On this device, run setenforce 0 to make the libraries readable.\n", prefix);
505 #endif
506 _LOG(log, logtype::BACKTRACE, "%sNOTE: Unreadable libraries:\n", prefix);
507 for (auto& name : unreadable_elf_files) {
508 _LOG(log, logtype::BACKTRACE, "%sNOTE: %s\n", prefix, name.c_str());
509 }
510 }
511
512 for (const auto& frame : unwinder->frames()) {
513 _LOG(log, logtype::BACKTRACE, "%s%s\n", prefix, unwinder->FormatFrame(frame).c_str());
514 }
515 }
516