1 /*
2 * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <signal.h>
29 #include <errno.h>
30 #include <elf.h>
31 #include <dirent.h>
32 #include <ctype.h>
33 #include <sys/types.h>
34 #include <sys/wait.h>
35 #include <sys/ptrace.h>
36 #include <sys/uio.h>
37 #include "libproc_impl.h"
38
39 #if defined(x86_64) && !defined(amd64)
40 #define amd64 1
41 #endif
42
43 #ifndef __WALL
44 #define __WALL 0x40000000 // Copied from /usr/include/linux/wait.h
45 #endif
46
47 // This file has the libproc implementation specific to live process
48 // For core files, refer to ps_core.c
49
50 typedef enum {
51 ATTACH_SUCCESS,
52 ATTACH_FAIL,
53 ATTACH_THREAD_DEAD
54 } attach_state_t;
55
56 static inline uintptr_t align(uintptr_t ptr, size_t size) {
57 return (ptr & ~(size - 1));
58 }
59
60 // ---------------------------------------------
61 // ptrace functions
62 // ---------------------------------------------
63
64 // read "size" bytes of data from "addr" within the target process.
65 // unlike the standard ptrace() function, process_read_data() can handle
66 // unaligned address - alignment check, if required, should be done
67 // before calling process_read_data.
68
69 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
70 long rslt;
71 size_t i, words;
72 uintptr_t end_addr = addr + size;
73 uintptr_t aligned_addr = align(addr, sizeof(long));
74
75 if (aligned_addr != addr) {
76 char *ptr = (char *)&rslt;
77 errno = 0;
78 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
79 if (errno) {
80 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
81 return false;
82 }
83 for (; aligned_addr != addr; aligned_addr++, ptr++);
84 for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr;
85 aligned_addr++)
86 *(buf++) = *(ptr++);
87 }
88
89 words = (end_addr - aligned_addr) / sizeof(long);
90
91 // assert((intptr_t)aligned_addr % sizeof(long) == 0);
92 for (i = 0; i < words; i++) {
93 errno = 0;
94 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
95 if (errno) {
96 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
97 return false;
98 }
99 *(long *)buf = rslt;
100 buf += sizeof(long);
101 aligned_addr += sizeof(long);
102 }
103
104 if (aligned_addr != end_addr) {
105 char *ptr = (char *)&rslt;
106 errno = 0;
107 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
108 if (errno) {
109 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
110 return false;
111 }
112 for (; aligned_addr != end_addr; aligned_addr++)
113 *(buf++) = *(ptr++);
114 }
115 return true;
116 }
117
118 // null implementation for write
119 static bool process_write_data(struct ps_prochandle* ph,
120 uintptr_t addr, const char *buf , size_t size) {
121 return false;
122 }
123
124 // "user" should be a pointer to a user_regs_struct
125 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) {
126 // we have already attached to all thread 'pid's, just use ptrace call
127 // to get regset now. Note that we don't cache regset upfront for processes.
128 // Linux on x86 and sparc are different. On x86 ptrace(PTRACE_GETREGS, ...)
129 // uses pointer from 4th argument and ignores 3rd argument. On sparc it uses
130 // pointer from 3rd argument and ignores 4th argument
131 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
132
133 #if defined(_LP64) && defined(PTRACE_GETREGS64)
134 #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
135 #elif defined(PTRACE_GETREGS)
136 #define PTRACE_GETREGS_REQ PTRACE_GETREGS
137 #elif defined(PT_GETREGS)
138 #define PTRACE_GETREGS_REQ PT_GETREGS
139 #endif
140
141 #ifdef PTRACE_GETREGS_REQ
142 if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) {
143 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
144 return false;
145 }
146 return true;
147 #elif defined(PTRACE_GETREGSET)
148 struct iovec iov;
149 iov.iov_base = user;
150 iov.iov_len = sizeof(*user);
151 if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void*) &iov) < 0) {
152 print_debug("ptrace(PTRACE_GETREGSET, ...) failed for lwp %d\n", pid);
153 return false;
154 }
155 return true;
156 #else
157 print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n");
158 return false;
159 #endif
160
161 }
162
163 static bool ptrace_continue(pid_t pid, int signal) {
164 // pass the signal to the process so we don't swallow it
165 if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
166 print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
167 return false;
168 }
169 return true;
170 }
171
172 // waits until the ATTACH has stopped the process
173 // by signal SIGSTOP
174 static attach_state_t ptrace_waitpid(pid_t pid) {
175 int ret;
176 int status;
177 errno = 0;
178 while (true) {
179 // Wait for debuggee to stop.
180 ret = waitpid(pid, &status, 0);
181 if (ret == -1 && errno == ECHILD) {
182 // try cloned process.
183 ret = waitpid(pid, &status, __WALL);
184 }
185 if (ret >= 0) {
186 if (WIFSTOPPED(status)) {
187 // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
188 // will still be pending and delivered when the process is DETACHED and the process
189 // will go to sleep.
190 if (WSTOPSIG(status) == SIGSTOP) {
191 // Debuggee stopped by SIGSTOP.
192 return ATTACH_SUCCESS;
193 }
194 if (!ptrace_continue(pid, WSTOPSIG(status))) {
195 print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
196 return ATTACH_FAIL;
197 }
198 } else {
199 print_debug("waitpid(): Child process %d exited/terminated (status = 0x%x)\n", pid, status);
200 return ATTACH_THREAD_DEAD;
201 }
202 } else {
203 switch (errno) {
204 case EINTR:
205 continue;
206 break;
207 case ECHILD:
208 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
209 return ATTACH_THREAD_DEAD;
210 case EINVAL:
211 print_error("waitpid() failed. Invalid options argument.\n");
212 return ATTACH_FAIL;
213 default:
214 print_error("waitpid() failed. Unexpected error %d\n", errno);
215 return ATTACH_FAIL;
216 }
217 } // else
218 } // while
219 }
220
221 // checks the state of the thread/process specified by "pid", by reading
222 // in the 'State:' value from the /proc/<pid>/status file. From the proc
223 // man page, "Current state of the process. One of "R (running)",
224 // "S (sleeping)", "D (disk sleep)", "T (stopped)", "T (tracing stop)",
225 // "Z (zombie)", or "X (dead)"." Assumes that the thread is dead if we
226 // don't find the status file or if the status is 'X' or 'Z'.
227 static bool process_doesnt_exist(pid_t pid) {
228 char fname[32];
229 char buf[30];
230 FILE *fp = NULL;
231 const char state_string[] = "State:";
232
233 sprintf(fname, "/proc/%d/status", pid);
234 fp = fopen(fname, "r");
235 if (fp == NULL) {
236 print_debug("can't open /proc/%d/status file\n", pid);
237 // Assume the thread does not exist anymore.
238 return true;
239 }
240 bool found_state = false;
241 size_t state_len = strlen(state_string);
242 while (fgets(buf, sizeof(buf), fp) != NULL) {
243 char *state = NULL;
244 if (strncmp (buf, state_string, state_len) == 0) {
245 found_state = true;
246 state = buf + state_len;
247 // Skip the spaces
248 while (isspace(*state)) {
249 state++;
250 }
251 // A state value of 'X' indicates that the thread is dead. 'Z'
252 // indicates that the thread is a zombie.
253 if (*state == 'X' || *state == 'Z') {
254 fclose (fp);
255 return true;
256 }
257 break;
258 }
259 }
260 // If the state value is not 'X' or 'Z', the thread exists.
261 if (!found_state) {
262 // We haven't found the line beginning with 'State:'.
263 // Assuming the thread exists.
264 print_error("Could not find the 'State:' string in the /proc/%d/status file\n", pid);
265 }
266 fclose (fp);
267 return false;
268 }
269
270 // attach to a process/thread specified by "pid"
271 static attach_state_t ptrace_attach(pid_t pid, char* err_buf, size_t err_buf_len) {
272 errno = 0;
273 if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {
274 if (errno == EPERM || errno == ESRCH) {
275 // Check if the process/thread is exiting or is a zombie
276 if (process_doesnt_exist(pid)) {
277 print_debug("Thread with pid %d does not exist\n", pid);
278 return ATTACH_THREAD_DEAD;
279 }
280 }
281 char buf[200];
282 char* msg = strerror_r(errno, buf, sizeof(buf));
283 snprintf(err_buf, err_buf_len, "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, msg);
284 print_error("%s\n", err_buf);
285 return ATTACH_FAIL;
286 } else {
287 attach_state_t wait_ret = ptrace_waitpid(pid);
288 if (wait_ret == ATTACH_THREAD_DEAD) {
289 print_debug("Thread with pid %d does not exist\n", pid);
290 }
291 return wait_ret;
292 }
293 }
294
295 // -------------------------------------------------------
296 // functions for obtaining library information
297 // -------------------------------------------------------
298
299 /*
300 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring
301 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.
302 * RETURN VALUE: total number of substrings (always <= _n_)
303 * NOTE: string _str_ is modified if _delim_!=_new_delim_
304 */
305 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)
306 {
307 int i;
308 for(i = 0; i < n; i++) ptrs[i] = NULL;
309 if (str == NULL || n < 1 ) return 0;
310
311 i = 0;
312
313 // skipping leading blanks
314 while(*str&&*str==delim) str++;
315
316 while(*str&&i<n){
317 ptrs[i++] = str;
318 while(*str&&*str!=delim) str++;
319 while(*str&&*str==delim) *(str++) = new_delim;
320 }
321
322 return i;
323 }
324
325 /*
326 * fgets without storing '\n' at the end of the string
327 */
328 static char * fgets_no_cr(char * buf, int n, FILE *fp)
329 {
330 char * rslt = fgets(buf, n, fp);
331 if (rslt && buf && *buf){
332 char *p = strchr(buf, '\0');
333 if (*--p=='\n') *p='\0';
334 }
335 return rslt;
336 }
337
338 static bool read_lib_info(struct ps_prochandle* ph) {
339 char fname[32];
340 char buf[PATH_MAX];
341 FILE *fp = NULL;
342
343 sprintf(fname, "/proc/%d/maps", ph->pid);
344 fp = fopen(fname, "r");
345 if (fp == NULL) {
346 print_debug("can't open /proc/%d/maps file\n", ph->pid);
347 return false;
348 }
349
350 while(fgets_no_cr(buf, PATH_MAX, fp)){
351 char * word[7];
352 int nwords = split_n_str(buf, 7, word, ' ', '\0');
353
354 if (nwords < 6) {
355 // not a shared library entry. ignore.
356 continue;
357 }
358
359 // SA does not handle the lines with patterns:
360 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc.
361 if (word[5][0] == '[') {
362 // not a shared library entry. ignore.
363 continue;
364 }
365
366 if (nwords > 6) {
367 // prelink altered mapfile when the program is running.
368 // Entries like one below have to be skipped
369 // /lib64/libc-2.15.so (deleted)
370 // SO name in entries like one below have to be stripped.
371 // /lib64/libpthread-2.15.so.#prelink#.EECVts
372 char *s = strstr(word[5],".#prelink#");
373 if (s == NULL) {
374 // No prelink keyword. skip deleted library
375 print_debug("skip shared object %s deleted by prelink\n", word[5]);
376 continue;
377 }
378
379 // Fall through
380 print_debug("rectifying shared object name %s changed by prelink\n", word[5]);
381 *s = 0;
382 }
383
384 if (find_lib(ph, word[5]) == false) {
385 intptr_t base;
386 lib_info* lib;
387 #ifdef _LP64
388 sscanf(word[0], "%lx", &base);
389 #else
390 sscanf(word[0], "%x", &base);
391 #endif
392 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)
393 continue; // ignore, add_lib_info prints error
394
395 // we don't need to keep the library open, symtab is already
396 // built. Only for core dump we need to keep the fd open.
397 close(lib->fd);
398 lib->fd = -1;
399 }
400 }
401 fclose(fp);
402 return true;
403 }
404
405 // detach a given pid
406 static bool ptrace_detach(pid_t pid) {
407 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {
408 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
409 return false;
410 } else {
411 return true;
412 }
413 }
414
415 // detach all pids of a ps_prochandle
416 static void detach_all_pids(struct ps_prochandle* ph) {
417 thread_info* thr = ph->threads;
418 while (thr) {
419 ptrace_detach(thr->lwp_id);
420 thr = thr->next;
421 }
422 }
423
424 static void process_cleanup(struct ps_prochandle* ph) {
425 detach_all_pids(ph);
426 }
427
428 static ps_prochandle_ops process_ops = {
429 .release= process_cleanup,
430 .p_pread= process_read_data,
431 .p_pwrite= process_write_data,
432 .get_lwp_regs= process_get_lwp_regs
433 };
434
435 // attach to the process. One and only one exposed stuff
436 JNIEXPORT struct ps_prochandle* JNICALL
437 Pgrab(pid_t pid, char* err_buf, size_t err_buf_len) {
438 struct ps_prochandle* ph = NULL;
439 thread_info* thr = NULL;
440 attach_state_t attach_status = ATTACH_SUCCESS;
441
442 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
443 snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle");
444 print_debug("%s\n", err_buf);
445 return NULL;
446 }
447
448 if ((attach_status = ptrace_attach(pid, err_buf, err_buf_len)) != ATTACH_SUCCESS) {
449 if (attach_status == ATTACH_THREAD_DEAD) {
450 print_error("The process with pid %d does not exist.\n", pid);
451 }
452 free(ph);
453 return NULL;
454 }
455
456 // initialize ps_prochandle
457 ph->pid = pid;
458 add_thread_info(ph, ph->pid);
459
460 // initialize vtable
461 ph->ops = &process_ops;
462
463 // read library info and symbol tables, must do this before attaching threads,
464 // as the symbols in the pthread library will be used to figure out
465 // the list of threads within the same process.
466 read_lib_info(ph);
467
468 /*
469 * Read thread info.
470 * SA scans all tasks in /proc/<PID>/task to read all threads info.
471 */
472 char taskpath[PATH_MAX];
473 DIR *dirp;
474 struct dirent *entry;
475
476 snprintf(taskpath, PATH_MAX, "/proc/%d/task", ph->pid);
477 dirp = opendir(taskpath);
478 int lwp_id;
479 while ((entry = readdir(dirp)) != NULL) {
480 if (*entry->d_name == '.') {
481 continue;
482 }
483 lwp_id = atoi(entry->d_name);
484 if (lwp_id == ph->pid) {
485 continue;
486 }
487 if (!process_doesnt_exist(lwp_id)) {
488 add_thread_info(ph, lwp_id);
489 }
490 }
491 closedir(dirp);
492
493 // attach to the threads
494 thr = ph->threads;
495
496 while (thr) {
497 thread_info* current_thr = thr;
498 thr = thr->next;
499 // don't attach to the main thread again
500 if (ph->pid != current_thr->lwp_id) {
501 if ((attach_status = ptrace_attach(current_thr->lwp_id, err_buf, err_buf_len)) != ATTACH_SUCCESS) {
502 if (attach_status == ATTACH_THREAD_DEAD) {
503 // Remove this thread from the threads list
504 delete_thread_info(ph, current_thr);
505 }
506 else {
507 Prelease(ph);
508 return NULL;
509 } // ATTACH_THREAD_DEAD
510 } // !ATTACH_SUCCESS
511 }
512 }
513 return ph;
514 }