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