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