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1 /* system/debuggerd/debuggerd.c
2 **
3 ** Copyright 2006, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 **     http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17 
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <unistd.h>
21 #include <errno.h>
22 #include <signal.h>
23 #include <pthread.h>
24 #include <stdarg.h>
25 #include <fcntl.h>
26 #include <sys/types.h>
27 #include <dirent.h>
28 
29 #include <sys/ptrace.h>
30 #include <sys/wait.h>
31 #include <sys/exec_elf.h>
32 #include <sys/stat.h>
33 
34 #include <cutils/sockets.h>
35 #include <cutils/logd.h>
36 #include <cutils/sockets.h>
37 #include <cutils/properties.h>
38 
39 #include <linux/input.h>
40 
41 #include <private/android_filesystem_config.h>
42 
43 #include "utility.h"
44 
45 #ifdef WITH_VFP
46 #ifdef WITH_VFP_D32
47 #define NUM_VFP_REGS 32
48 #else
49 #define NUM_VFP_REGS 16
50 #endif
51 #endif
52 
53 /* Main entry point to get the backtrace from the crashing process */
54 extern int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map,
55                                         unsigned int sp_list[],
56                                         int *frame0_pc_sane,
57                                         bool at_fault);
58 
59 static int logsocket = -1;
60 
61 #define ANDROID_LOG_INFO 4
62 
63 /* Log information onto the tombstone */
_LOG(int tfd,bool in_tombstone_only,const char * fmt,...)64 void _LOG(int tfd, bool in_tombstone_only, const char *fmt, ...)
65 {
66     char buf[128];
67 
68     va_list ap;
69     va_start(ap, fmt);
70 
71     if (tfd >= 0) {
72         int len;
73         vsnprintf(buf, sizeof(buf), fmt, ap);
74         len = strlen(buf);
75         if(tfd >= 0) write(tfd, buf, len);
76     }
77 
78     if (!in_tombstone_only)
79         __android_log_vprint(ANDROID_LOG_INFO, "DEBUG", fmt, ap);
80 }
81 
82 #define LOG(fmt...) _LOG(-1, 0, fmt)
83 #if 0
84 #define XLOG(fmt...) _LOG(-1, 0, fmt)
85 #else
86 #define XLOG(fmt...) do {} while(0)
87 #endif
88 
89 // 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so
90 // 012345678901234567890123456789012345678901234567890123456789
91 // 0         1         2         3         4         5
92 
parse_maps_line(char * line)93 mapinfo *parse_maps_line(char *line)
94 {
95     mapinfo *mi;
96     int len = strlen(line);
97 
98     if(len < 1) return 0;
99     line[--len] = 0;
100 
101     if(len < 50) return 0;
102     if(line[20] != 'x') return 0;
103 
104     mi = malloc(sizeof(mapinfo) + (len - 47));
105     if(mi == 0) return 0;
106 
107     mi->start = strtoul(line, 0, 16);
108     mi->end = strtoul(line + 9, 0, 16);
109     /* To be filled in parse_exidx_info if the mapped section starts with
110      * elf_header
111      */
112     mi->exidx_start = mi->exidx_end = 0;
113     mi->next = 0;
114     strcpy(mi->name, line + 49);
115 
116     return mi;
117 }
118 
dump_build_info(int tfd)119 void dump_build_info(int tfd)
120 {
121     char fingerprint[PROPERTY_VALUE_MAX];
122 
123     property_get("ro.build.fingerprint", fingerprint, "unknown");
124 
125     _LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
126 }
127 
128 
dump_stack_and_code(int tfd,int pid,mapinfo * map,int unwind_depth,unsigned int sp_list[],bool at_fault)129 void dump_stack_and_code(int tfd, int pid, mapinfo *map,
130                          int unwind_depth, unsigned int sp_list[],
131                          bool at_fault)
132 {
133     unsigned int sp, pc, p, end, data;
134     struct pt_regs r;
135     int sp_depth;
136     bool only_in_tombstone = !at_fault;
137     char code_buffer[80];
138 
139     if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return;
140     sp = r.ARM_sp;
141     pc = r.ARM_pc;
142 
143     _LOG(tfd, only_in_tombstone, "\ncode around pc:\n");
144 
145     end = p = pc & ~3;
146     p -= 32;
147     end += 32;
148 
149     /* Dump the code around PC as:
150      *  addr       contents
151      *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
152      *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
153      */
154     while (p <= end) {
155         int i;
156 
157         sprintf(code_buffer, "%08x ", p);
158         for (i = 0; i < 4; i++) {
159             data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
160             sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
161             p += 4;
162         }
163         _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
164     }
165 
166     if ((unsigned) r.ARM_lr != pc) {
167         _LOG(tfd, only_in_tombstone, "\ncode around lr:\n");
168 
169         end = p = r.ARM_lr & ~3;
170         p -= 32;
171         end += 32;
172 
173         /* Dump the code around LR as:
174          *  addr       contents
175          *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
176          *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
177          */
178         while (p <= end) {
179             int i;
180 
181             sprintf(code_buffer, "%08x ", p);
182             for (i = 0; i < 4; i++) {
183                 data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
184                 sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
185                 p += 4;
186             }
187             _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
188         }
189     }
190 
191     p = sp - 64;
192     p &= ~3;
193     if (unwind_depth != 0) {
194         if (unwind_depth < STACK_CONTENT_DEPTH) {
195             end = sp_list[unwind_depth-1];
196         }
197         else {
198             end = sp_list[STACK_CONTENT_DEPTH-1];
199         }
200     }
201     else {
202         end = sp | 0x000000ff;
203         end += 0xff;
204     }
205 
206     _LOG(tfd, only_in_tombstone, "\nstack:\n");
207 
208     /* If the crash is due to PC == 0, there will be two frames that
209      * have identical SP value.
210      */
211     if (sp_list[0] == sp_list[1]) {
212         sp_depth = 1;
213     }
214     else {
215         sp_depth = 0;
216     }
217 
218     while (p <= end) {
219          char *prompt;
220          char level[16];
221          data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
222          if (p == sp_list[sp_depth]) {
223              sprintf(level, "#%02d", sp_depth++);
224              prompt = level;
225          }
226          else {
227              prompt = "   ";
228          }
229 
230          /* Print the stack content in the log for the first 3 frames. For the
231           * rest only print them in the tombstone file.
232           */
233          _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
234               "%s %08x  %08x  %s\n", prompt, p, data,
235               map_to_name(map, data, ""));
236          p += 4;
237     }
238     /* print another 64-byte of stack data after the last frame */
239 
240     end = p+64;
241     while (p <= end) {
242          data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
243          _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
244               "    %08x  %08x  %s\n", p, data,
245               map_to_name(map, data, ""));
246          p += 4;
247     }
248 }
249 
dump_pc_and_lr(int tfd,int pid,mapinfo * map,int unwound_level,bool at_fault)250 void dump_pc_and_lr(int tfd, int pid, mapinfo *map, int unwound_level,
251                     bool at_fault)
252 {
253     struct pt_regs r;
254 
255     if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
256         _LOG(tfd, !at_fault, "tid %d not responding!\n", pid);
257         return;
258     }
259 
260     if (unwound_level == 0) {
261         _LOG(tfd, !at_fault, "         #%02d  pc %08x  %s\n", 0, r.ARM_pc,
262              map_to_name(map, r.ARM_pc, "<unknown>"));
263     }
264     _LOG(tfd, !at_fault, "         #%02d  lr %08x  %s\n", 1, r.ARM_lr,
265             map_to_name(map, r.ARM_lr, "<unknown>"));
266 }
267 
dump_registers(int tfd,int pid,bool at_fault)268 void dump_registers(int tfd, int pid, bool at_fault)
269 {
270     struct pt_regs r;
271     bool only_in_tombstone = !at_fault;
272 
273     if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
274         _LOG(tfd, only_in_tombstone,
275              "cannot get registers: %s\n", strerror(errno));
276         return;
277     }
278 
279     _LOG(tfd, only_in_tombstone, " r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
280          r.ARM_r0, r.ARM_r1, r.ARM_r2, r.ARM_r3);
281     _LOG(tfd, only_in_tombstone, " r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
282          r.ARM_r4, r.ARM_r5, r.ARM_r6, r.ARM_r7);
283     _LOG(tfd, only_in_tombstone, " r8 %08x  r9 %08x  10 %08x  fp %08x\n",
284          r.ARM_r8, r.ARM_r9, r.ARM_r10, r.ARM_fp);
285     _LOG(tfd, only_in_tombstone,
286          " ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
287          r.ARM_ip, r.ARM_sp, r.ARM_lr, r.ARM_pc, r.ARM_cpsr);
288 
289 #ifdef WITH_VFP
290     struct user_vfp vfp_regs;
291     int i;
292 
293     if(ptrace(PTRACE_GETVFPREGS, pid, 0, &vfp_regs)) {
294         _LOG(tfd, only_in_tombstone,
295              "cannot get registers: %s\n", strerror(errno));
296         return;
297     }
298 
299     for (i = 0; i < NUM_VFP_REGS; i += 2) {
300         _LOG(tfd, only_in_tombstone,
301              " d%-2d %016llx  d%-2d %016llx\n",
302               i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
303     }
304     _LOG(tfd, only_in_tombstone, " scr %08lx\n\n", vfp_regs.fpscr);
305 #endif
306 }
307 
get_signame(int sig)308 const char *get_signame(int sig)
309 {
310     switch(sig) {
311     case SIGILL:     return "SIGILL";
312     case SIGABRT:    return "SIGABRT";
313     case SIGBUS:     return "SIGBUS";
314     case SIGFPE:     return "SIGFPE";
315     case SIGSEGV:    return "SIGSEGV";
316     case SIGSTKFLT:  return "SIGSTKFLT";
317     default:         return "?";
318     }
319 }
320 
get_sigcode(int signo,int code)321 const char *get_sigcode(int signo, int code)
322 {
323     switch (signo) {
324     case SIGILL:
325         switch (code) {
326         case ILL_ILLOPC: return "ILL_ILLOPC";
327         case ILL_ILLOPN: return "ILL_ILLOPN";
328         case ILL_ILLADR: return "ILL_ILLADR";
329         case ILL_ILLTRP: return "ILL_ILLTRP";
330         case ILL_PRVOPC: return "ILL_PRVOPC";
331         case ILL_PRVREG: return "ILL_PRVREG";
332         case ILL_COPROC: return "ILL_COPROC";
333         case ILL_BADSTK: return "ILL_BADSTK";
334         }
335         break;
336     case SIGBUS:
337         switch (code) {
338         case BUS_ADRALN: return "BUS_ADRALN";
339         case BUS_ADRERR: return "BUS_ADRERR";
340         case BUS_OBJERR: return "BUS_OBJERR";
341         }
342         break;
343     case SIGFPE:
344         switch (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         }
354         break;
355     case SIGSEGV:
356         switch (code) {
357         case SEGV_MAPERR: return "SEGV_MAPERR";
358         case SEGV_ACCERR: return "SEGV_ACCERR";
359         }
360         break;
361     }
362     return "?";
363 }
364 
dump_fault_addr(int tfd,int pid,int sig)365 void dump_fault_addr(int tfd, int pid, int sig)
366 {
367     siginfo_t si;
368 
369     memset(&si, 0, sizeof(si));
370     if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
371         _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
372     } else {
373         _LOG(tfd, false, "signal %d (%s), code %d (%s), fault addr %08x\n",
374              sig, get_signame(sig),
375              si.si_code, get_sigcode(sig, si.si_code),
376              si.si_addr);
377     }
378 }
379 
dump_crash_banner(int tfd,unsigned pid,unsigned tid,int sig)380 void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
381 {
382     char data[1024];
383     char *x = 0;
384     FILE *fp;
385 
386     sprintf(data, "/proc/%d/cmdline", pid);
387     fp = fopen(data, "r");
388     if(fp) {
389         x = fgets(data, 1024, fp);
390         fclose(fp);
391     }
392 
393     _LOG(tfd, false,
394          "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
395     dump_build_info(tfd);
396     _LOG(tfd, false, "pid: %d, tid: %d  >>> %s <<<\n",
397          pid, tid, x ? x : "UNKNOWN");
398 
399     if(sig) dump_fault_addr(tfd, tid, sig);
400 }
401 
parse_exidx_info(mapinfo * milist,pid_t pid)402 static void parse_exidx_info(mapinfo *milist, pid_t pid)
403 {
404     mapinfo *mi;
405     for (mi = milist; mi != NULL; mi = mi->next) {
406         Elf32_Ehdr ehdr;
407 
408         memset(&ehdr, 0, sizeof(Elf32_Ehdr));
409         /* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
410          * mapped section.
411          */
412         get_remote_struct(pid, (void *) (mi->start), &ehdr,
413                           sizeof(Elf32_Ehdr));
414         /* Check if it has the matching magic words */
415         if (IS_ELF(ehdr)) {
416             Elf32_Phdr phdr;
417             Elf32_Phdr *ptr;
418             int i;
419 
420             ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
421             for (i = 0; i < ehdr.e_phnum; i++) {
422                 /* Parse the program header */
423                 get_remote_struct(pid, (char *) (ptr+i), &phdr,
424                                   sizeof(Elf32_Phdr));
425                 /* Found a EXIDX segment? */
426                 if (phdr.p_type == PT_ARM_EXIDX) {
427                     mi->exidx_start = mi->start + phdr.p_offset;
428                     mi->exidx_end = mi->exidx_start + phdr.p_filesz;
429                     break;
430                 }
431             }
432         }
433     }
434 }
435 
dump_crash_report(int tfd,unsigned pid,unsigned tid,bool at_fault)436 void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
437 {
438     char data[1024];
439     FILE *fp;
440     mapinfo *milist = 0;
441     unsigned int sp_list[STACK_CONTENT_DEPTH];
442     int stack_depth;
443     int frame0_pc_sane = 1;
444 
445     if (!at_fault) {
446         _LOG(tfd, true,
447          "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
448         _LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
449     }
450 
451     dump_registers(tfd, tid, at_fault);
452 
453     /* Clear stack pointer records */
454     memset(sp_list, 0, sizeof(sp_list));
455 
456     sprintf(data, "/proc/%d/maps", pid);
457     fp = fopen(data, "r");
458     if(fp) {
459         while(fgets(data, 1024, fp)) {
460             mapinfo *mi = parse_maps_line(data);
461             if(mi) {
462                 mi->next = milist;
463                 milist = mi;
464             }
465         }
466         fclose(fp);
467     }
468 
469     parse_exidx_info(milist, tid);
470 
471     /* If stack unwinder fails, use the default solution to dump the stack
472      * content.
473      */
474     stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
475                                                &frame0_pc_sane, at_fault);
476 
477     /* The stack unwinder should at least unwind two levels of stack. If less
478      * level is seen we make sure at lease pc and lr are dumped.
479      */
480     if (stack_depth < 2) {
481         dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
482     }
483 
484     dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, at_fault);
485 
486     while(milist) {
487         mapinfo *next = milist->next;
488         free(milist);
489         milist = next;
490     }
491 }
492 
493 #define MAX_TOMBSTONES	10
494 
495 #define typecheck(x,y) {    \
496     typeof(x) __dummy1;     \
497     typeof(y) __dummy2;     \
498     (void)(&__dummy1 == &__dummy2); }
499 
500 #define TOMBSTONE_DIR	"/data/tombstones"
501 
502 /*
503  * find_and_open_tombstone - find an available tombstone slot, if any, of the
504  * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
505  * file is available, we reuse the least-recently-modified file.
506  */
find_and_open_tombstone(void)507 static int find_and_open_tombstone(void)
508 {
509     unsigned long mtime = ULONG_MAX;
510     struct stat sb;
511     char path[128];
512     int fd, i, oldest = 0;
513 
514     /*
515      * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
516      * to, our logic breaks. This check will generate a warning if that happens.
517      */
518     typecheck(mtime, sb.st_mtime);
519 
520     /*
521      * In a single wolf-like pass, find an available slot and, in case none
522      * exist, find and record the least-recently-modified file.
523      */
524     for (i = 0; i < MAX_TOMBSTONES; i++) {
525         snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
526 
527         if (!stat(path, &sb)) {
528             if (sb.st_mtime < mtime) {
529                 oldest = i;
530                 mtime = sb.st_mtime;
531             }
532             continue;
533         }
534         if (errno != ENOENT)
535             continue;
536 
537         fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
538         if (fd < 0)
539             continue;	/* raced ? */
540 
541         fchown(fd, AID_SYSTEM, AID_SYSTEM);
542         return fd;
543     }
544 
545     /* we didn't find an available file, so we clobber the oldest one */
546     snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
547     fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
548     fchown(fd, AID_SYSTEM, AID_SYSTEM);
549 
550     return fd;
551 }
552 
553 /* Return true if some thread is not detached cleanly */
dump_sibling_thread_report(int tfd,unsigned pid,unsigned tid)554 static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
555 {
556     char task_path[1024];
557 
558     sprintf(task_path, "/proc/%d/task", pid);
559     DIR *d;
560     struct dirent *de;
561     int need_cleanup = 0;
562 
563     d = opendir(task_path);
564     /* Bail early if cannot open the task directory */
565     if (d == NULL) {
566         XLOG("Cannot open /proc/%d/task\n", pid);
567         return false;
568     }
569     while ((de = readdir(d)) != NULL) {
570         unsigned new_tid;
571         /* Ignore "." and ".." */
572         if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
573             continue;
574         new_tid = atoi(de->d_name);
575         /* The main thread at fault has been handled individually */
576         if (new_tid == tid)
577             continue;
578 
579         /* Skip this thread if cannot ptrace it */
580         if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
581             continue;
582 
583         dump_crash_report(tfd, pid, new_tid, false);
584         need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
585     }
586     closedir(d);
587     return need_cleanup != 0;
588 }
589 
590 /* Return true if some thread is not detached cleanly */
engrave_tombstone(unsigned pid,unsigned tid,int debug_uid,int signal)591 static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
592                               int signal)
593 {
594     int fd;
595     bool need_cleanup = false;
596 
597     mkdir(TOMBSTONE_DIR, 0755);
598     chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
599 
600     fd = find_and_open_tombstone();
601     if (fd < 0)
602         return need_cleanup;
603 
604     dump_crash_banner(fd, pid, tid, signal);
605     dump_crash_report(fd, pid, tid, true);
606     /*
607      * If the user has requested to attach gdb, don't collect the per-thread
608      * information as it increases the chance to lose track of the process.
609      */
610     if ((signed)pid > debug_uid) {
611         need_cleanup = dump_sibling_thread_report(fd, pid, tid);
612     }
613 
614     close(fd);
615     return need_cleanup;
616 }
617 
618 static int
write_string(const char * file,const char * string)619 write_string(const char* file, const char* string)
620 {
621     int len;
622     int fd;
623     ssize_t amt;
624     fd = open(file, O_RDWR);
625     len = strlen(string);
626     if (fd < 0)
627         return -errno;
628     amt = write(fd, string, len);
629     close(fd);
630     return amt >= 0 ? 0 : -errno;
631 }
632 
633 static
init_debug_led(void)634 void init_debug_led(void)
635 {
636     // trout leds
637     write_string("/sys/class/leds/red/brightness", "0");
638     write_string("/sys/class/leds/green/brightness", "0");
639     write_string("/sys/class/leds/blue/brightness", "0");
640     write_string("/sys/class/leds/red/device/blink", "0");
641     // sardine leds
642     write_string("/sys/class/leds/left/cadence", "0,0");
643 }
644 
645 static
enable_debug_led(void)646 void enable_debug_led(void)
647 {
648     // trout leds
649     write_string("/sys/class/leds/red/brightness", "255");
650     // sardine leds
651     write_string("/sys/class/leds/left/cadence", "1,0");
652 }
653 
654 static
disable_debug_led(void)655 void disable_debug_led(void)
656 {
657     // trout leds
658     write_string("/sys/class/leds/red/brightness", "0");
659     // sardine leds
660     write_string("/sys/class/leds/left/cadence", "0,0");
661 }
662 
663 extern int init_getevent();
664 extern void uninit_getevent();
665 extern int get_event(struct input_event* event, int timeout);
666 
wait_for_user_action(unsigned tid,struct ucred * cr)667 static void wait_for_user_action(unsigned tid, struct ucred* cr)
668 {
669     (void)tid;
670     /* First log a helpful message */
671     LOG(    "********************************************************\n"
672             "* Process %d has been suspended while crashing.  To\n"
673             "* attach gdbserver for a gdb connection on port 5039:\n"
674             "*\n"
675             "*     adb shell gdbserver :5039 --attach %d &\n"
676             "*\n"
677             "* Press HOME key to let the process continue crashing.\n"
678             "********************************************************\n",
679             cr->pid, cr->pid);
680 
681     /* wait for HOME key (TODO: something useful for devices w/o HOME key) */
682     if (init_getevent() == 0) {
683         int ms = 1200 / 10;
684         int dit = 1;
685         int dah = 3*dit;
686         int _       = -dit;
687         int ___     = 3*_;
688         int _______ = 7*_;
689         const signed char codes[] = {
690            dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
691         };
692         size_t s = 0;
693         struct input_event e;
694         int home = 0;
695         init_debug_led();
696         enable_debug_led();
697         do {
698             int timeout = abs((int)(codes[s])) * ms;
699             int res = get_event(&e, timeout);
700             if (res == 0) {
701                 if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
702                     home = 1;
703             } else if (res == 1) {
704                 if (++s >= sizeof(codes)/sizeof(*codes))
705                     s = 0;
706                 if (codes[s] > 0) {
707                     enable_debug_led();
708                 } else {
709                     disable_debug_led();
710                 }
711             }
712         } while (!home);
713         uninit_getevent();
714     }
715 
716     /* don't forget to turn debug led off */
717     disable_debug_led();
718 
719     /* close filedescriptor */
720     LOG("debuggerd resuming process %d", cr->pid);
721  }
722 
handle_crashing_process(int fd)723 static void handle_crashing_process(int fd)
724 {
725     char buf[64];
726     struct stat s;
727     unsigned tid;
728     struct ucred cr;
729     int n, len, status;
730     int tid_attach_status = -1;
731     unsigned retry = 30;
732     bool need_cleanup = false;
733 
734     char value[PROPERTY_VALUE_MAX];
735     property_get("debug.db.uid", value, "-1");
736     int debug_uid = atoi(value);
737 
738     XLOG("handle_crashing_process(%d)\n", fd);
739 
740     len = sizeof(cr);
741     n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
742     if(n != 0) {
743         LOG("cannot get credentials\n");
744         goto done;
745     }
746 
747     XLOG("reading tid\n");
748     fcntl(fd, F_SETFL, O_NONBLOCK);
749     while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
750         if(errno == EINTR) continue;
751         if(errno == EWOULDBLOCK) {
752             if(retry-- > 0) {
753                 usleep(100 * 1000);
754                 continue;
755             }
756             LOG("timed out reading tid\n");
757             goto done;
758         }
759         LOG("read failure? %s\n", strerror(errno));
760         goto done;
761     }
762 
763     sprintf(buf,"/proc/%d/task/%d", cr.pid, tid);
764     if(stat(buf, &s)) {
765         LOG("tid %d does not exist in pid %d. ignoring debug request\n",
766             tid, cr.pid);
767         close(fd);
768         return;
769     }
770 
771     XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
772 
773     tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
774     if(tid_attach_status < 0) {
775         LOG("ptrace attach failed: %s\n", strerror(errno));
776         goto done;
777     }
778 
779     close(fd);
780     fd = -1;
781 
782     for(;;) {
783         n = waitpid(tid, &status, __WALL);
784 
785         if(n < 0) {
786             if(errno == EAGAIN) continue;
787             LOG("waitpid failed: %s\n", strerror(errno));
788             goto done;
789         }
790 
791         XLOG("waitpid: n=%d status=%08x\n", n, status);
792 
793         if(WIFSTOPPED(status)){
794             n = WSTOPSIG(status);
795             switch(n) {
796             case SIGSTOP:
797                 XLOG("stopped -- continuing\n");
798                 n = ptrace(PTRACE_CONT, tid, 0, 0);
799                 if(n) {
800                     LOG("ptrace failed: %s\n", strerror(errno));
801                     goto done;
802                 }
803                 continue;
804 
805             case SIGILL:
806             case SIGABRT:
807             case SIGBUS:
808             case SIGFPE:
809             case SIGSEGV:
810             case SIGSTKFLT: {
811                 XLOG("stopped -- fatal signal\n");
812                 need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
813                 kill(tid, SIGSTOP);
814                 goto done;
815             }
816 
817             default:
818                 XLOG("stopped -- unexpected signal\n");
819                 goto done;
820             }
821         } else {
822             XLOG("unexpected waitpid response\n");
823             goto done;
824         }
825     }
826 
827 done:
828     XLOG("detaching\n");
829 
830     /* stop the process so we can debug */
831     kill(cr.pid, SIGSTOP);
832 
833     /*
834      * If a thread has been attached by ptrace, make sure it is detached
835      * successfully otherwise we will get a zombie.
836      */
837     if (tid_attach_status == 0) {
838         int detach_status;
839         /* detach so we can attach gdbserver */
840         detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
841         need_cleanup |= (detach_status != 0);
842     }
843 
844     /*
845      * if debug.db.uid is set, its value indicates if we should wait
846      * for user action for the crashing process.
847      * in this case, we log a message and turn the debug LED on
848      * waiting for a gdb connection (for instance)
849      */
850 
851     if ((signed)cr.uid <= debug_uid) {
852         wait_for_user_action(tid, &cr);
853     }
854 
855     /* resume stopped process (so it can crash in peace) */
856     kill(cr.pid, SIGCONT);
857 
858     if (need_cleanup) {
859         LOG("debuggerd committing suicide to free the zombie!\n");
860         kill(getpid(), SIGKILL);
861     }
862 
863     if(fd != -1) close(fd);
864 }
865 
main()866 int main()
867 {
868     int s;
869     struct sigaction act;
870 
871     logsocket = socket_local_client("logd",
872             ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
873     if(logsocket < 0) {
874         logsocket = -1;
875     } else {
876         fcntl(logsocket, F_SETFD, FD_CLOEXEC);
877     }
878 
879     act.sa_handler = SIG_DFL;
880     sigemptyset(&act.sa_mask);
881     sigaddset(&act.sa_mask,SIGCHLD);
882     act.sa_flags = SA_NOCLDWAIT;
883     sigaction(SIGCHLD, &act, 0);
884 
885     s = socket_local_server("android:debuggerd",
886             ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
887     if(s < 0) return -1;
888     fcntl(s, F_SETFD, FD_CLOEXEC);
889 
890     LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
891 
892     for(;;) {
893         struct sockaddr addr;
894         socklen_t alen;
895         int fd;
896 
897         alen = sizeof(addr);
898         fd = accept(s, &addr, &alen);
899         if(fd < 0) continue;
900 
901         fcntl(fd, F_SETFD, FD_CLOEXEC);
902 
903         handle_crashing_process(fd);
904     }
905     return 0;
906 }
907