1 /*
2 * Copyright (c) 2003, 2017, 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 <sys/types.h>
32 #include <sys/wait.h>
33 #include <sys/ptrace.h>
34 #include <sys/uio.h>
35 #ifndef INCLUDE_SA_ATTACH
36 #include <dirent.h>
37 #endif
38 #include "libproc_impl.h"
39
40 #if defined(x86_64) && !defined(amd64)
41 #define amd64 1
42 #endif
43
44 #ifndef __WALL
45 #define __WALL 0x40000000 // Copied from /usr/include/linux/wait.h
46 #endif
47
48 // This file has the libproc implementation specific to live process
49 // For core files, refer to ps_core.c
50
51 static inline uintptr_t align(uintptr_t ptr, size_t size) {
52 return (ptr & ~(size - 1));
53 }
54
55 // ---------------------------------------------
56 // ptrace functions
57 // ---------------------------------------------
58
59 // read "size" bytes of data from "addr" within the target process.
60 // unlike the standard ptrace() function, process_read_data() can handle
61 // unaligned address - alignment check, if required, should be done
62 // before calling process_read_data.
63
64 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
65 long rslt;
66 size_t i, words;
67 uintptr_t end_addr = addr + size;
68 uintptr_t aligned_addr = align(addr, sizeof(long));
69
70 if (aligned_addr != addr) {
71 char *ptr = (char *)&rslt;
72 errno = 0;
73 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
74 if (errno) {
75 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
76 return false;
77 }
78 for (; aligned_addr != addr; aligned_addr++, ptr++);
79 for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr;
80 aligned_addr++)
81 *(buf++) = *(ptr++);
82 }
83
84 words = (end_addr - aligned_addr) / sizeof(long);
85
86 // assert((intptr_t)aligned_addr % sizeof(long) == 0);
87 for (i = 0; i < words; i++) {
88 errno = 0;
89 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
90 if (errno) {
91 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
92 return false;
93 }
94 *(long *)buf = rslt;
95 buf += sizeof(long);
96 aligned_addr += sizeof(long);
97 }
98
99 if (aligned_addr != end_addr) {
100 char *ptr = (char *)&rslt;
101 errno = 0;
102 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
103 if (errno) {
104 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
105 return false;
106 }
107 for (; aligned_addr != end_addr; aligned_addr++)
108 *(buf++) = *(ptr++);
109 }
110 return true;
111 }
112
113 // null implementation for write
114 static bool process_write_data(struct ps_prochandle* ph,
115 uintptr_t addr, const char *buf , size_t size) {
116 return false;
117 }
118
119 // "user" should be a pointer to a user_regs_struct
120 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) {
121 // we have already attached to all thread 'pid's, just use ptrace call
122 // to get regset now. Note that we don't cache regset upfront for processes.
123 // Linux on x86 and sparc are different. On x86 ptrace(PTRACE_GETREGS, ...)
124 // uses pointer from 4th argument and ignores 3rd argument. On sparc it uses
125 // pointer from 3rd argument and ignores 4th argument
126 #if defined(sparc) || defined(sparcv9)
127 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)
128 #else
129 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
130 #endif
131
132 #if defined(_LP64) && defined(PTRACE_GETREGS64)
133 #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
134 #elif defined(PTRACE_GETREGS)
135 #define PTRACE_GETREGS_REQ PTRACE_GETREGS
136 #elif defined(PT_GETREGS)
137 #define PTRACE_GETREGS_REQ PT_GETREGS
138 #endif
139
140 #ifdef PTRACE_GETREGS_REQ
141 if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) {
142 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
143 return false;
144 }
145 return true;
146 #elif defined(PTRACE_GETREGSET)
147 struct iovec iov;
148 iov.iov_base = user;
149 iov.iov_len = sizeof(*user);
150 if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void*) &iov) < 0) {
151 print_debug("ptrace(PTRACE_GETREGSET, ...) failed for lwp %d\n", pid);
152 return false;
153 }
154 return true;
155 #else
156 print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n");
157 return false;
158 #endif
159
160 }
161
162 static bool ptrace_continue(pid_t pid, int signal) {
163 // pass the signal to the process so we don't swallow it
164 if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
165 print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
166 return false;
167 }
168 return true;
169 }
170
171 // waits until the ATTACH has stopped the process
172 // by signal SIGSTOP
173 static bool ptrace_waitpid(pid_t pid) {
174 int ret;
175 int status;
176 while (true) {
177 // Wait for debuggee to stop.
178 ret = waitpid(pid, &status, 0);
179 if (ret == -1 && errno == ECHILD) {
180 // try cloned process.
181 ret = waitpid(pid, &status, __WALL);
182 }
183 if (ret >= 0) {
184 if (WIFSTOPPED(status)) {
185 // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
186 // will still be pending and delivered when the process is DETACHED and the process
187 // will go to sleep.
188 if (WSTOPSIG(status) == SIGSTOP) {
189 // Debuggee stopped by SIGSTOP.
190 return true;
191 }
192 if (!ptrace_continue(pid, WSTOPSIG(status))) {
193 print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
194 return false;
195 }
196 } else {
197 print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
198 return false;
199 }
200 } else {
201 switch (errno) {
202 case EINTR:
203 continue;
204 break;
205 case ECHILD:
206 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
207 break;
208 case EINVAL:
209 print_debug("waitpid() failed. Invalid options argument.\n");
210 break;
211 default:
212 print_debug("waitpid() failed. Unexpected error %d\n",errno);
213 break;
214 }
215 return false;
216 }
217 }
218 }
219
220 // attach to a process/thread specified by "pid"
221 static bool ptrace_attach(pid_t pid, char* err_buf, size_t err_buf_len) {
222 if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {
223 char buf[200];
224 if (strerror_r(errno, buf, sizeof(buf) == 0)) {
225 snprintf(err_buf, err_buf_len,
226 "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, buf);
227 print_debug("%s\n", err_buf);
228 }
229 return false;
230 } else {
231 return ptrace_waitpid(pid);
232 }
233 }
234
235 // -------------------------------------------------------
236 // functions for obtaining library information
237 // -------------------------------------------------------
238
239 /*
240 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring
241 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.
242 * RETURN VALUE: total number of substrings (always <= _n_)
243 * NOTE: string _str_ is modified if _delim_!=_new_delim_
244 */
245 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)
246 {
247 int i;
248 for(i = 0; i < n; i++) ptrs[i] = NULL;
249 if (str == NULL || n < 1 ) return 0;
250
251 i = 0;
252
253 // skipping leading blanks
254 while(*str&&*str==delim) str++;
255
256 while(*str&&i<n){
257 ptrs[i++] = str;
258 while(*str&&*str!=delim) str++;
259 while(*str&&*str==delim) *(str++) = new_delim;
260 }
261
262 return i;
263 }
264
265 /*
266 * fgets without storing '\n' at the end of the string
267 */
268 static char * fgets_no_cr(char * buf, int n, FILE *fp)
269 {
270 char * rslt = fgets(buf, n, fp);
271 if (rslt && buf && *buf){
272 char *p = strchr(buf, '\0');
273 if (*--p=='\n') *p='\0';
274 }
275 return rslt;
276 }
277
278 // callback for read_thread_info
279 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
280 return add_thread_info(ph, pthread_id, lwp_id) != NULL;
281 }
282
283 static bool read_lib_info(struct ps_prochandle* ph) {
284 char fname[32];
285 char buf[PATH_MAX];
286 FILE *fp = NULL;
287
288 sprintf(fname, "/proc/%d/maps", ph->pid);
289 fp = fopen(fname, "r");
290 if (fp == NULL) {
291 print_debug("can't open /proc/%d/maps file\n", ph->pid);
292 return false;
293 }
294
295 while(fgets_no_cr(buf, PATH_MAX, fp)){
296 char * word[7];
297 int nwords = split_n_str(buf, 7, word, ' ', '\0');
298
299 if (nwords < 6) {
300 // not a shared library entry. ignore.
301 continue;
302 }
303
304 // SA does not handle the lines with patterns:
305 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc.
306 if (word[5][0] == '[') {
307 // not a shared library entry. ignore.
308 continue;
309 }
310
311 if (nwords > 6) {
312 // prelink altered mapfile when the program is running.
313 // Entries like one below have to be skipped
314 // /lib64/libc-2.15.so (deleted)
315 // SO name in entries like one below have to be stripped.
316 // /lib64/libpthread-2.15.so.#prelink#.EECVts
317 char *s = strstr(word[5],".#prelink#");
318 if (s == NULL) {
319 // No prelink keyword. skip deleted library
320 print_debug("skip shared object %s deleted by prelink\n", word[5]);
321 continue;
322 }
323
324 // Fall through
325 print_debug("rectifying shared object name %s changed by prelink\n", word[5]);
326 *s = 0;
327 }
328
329 if (find_lib(ph, word[5]) == false) {
330 intptr_t base;
331 lib_info* lib;
332 #ifdef _LP64
333 sscanf(word[0], "%lx", &base);
334 #else
335 sscanf(word[0], "%x", &base);
336 #endif
337 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)
338 continue; // ignore, add_lib_info prints error
339
340 // we don't need to keep the library open, symtab is already
341 // built. Only for core dump we need to keep the fd open.
342 close(lib->fd);
343 lib->fd = -1;
344 }
345 }
346 fclose(fp);
347 return true;
348 }
349
350 // detach a given pid
351 static bool ptrace_detach(pid_t pid) {
352 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {
353 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
354 return false;
355 } else {
356 return true;
357 }
358 }
359
360 // detach all pids of a ps_prochandle
361 static void detach_all_pids(struct ps_prochandle* ph) {
362 thread_info* thr = ph->threads;
363 while (thr) {
364 ptrace_detach(thr->lwp_id);
365 thr = thr->next;
366 }
367 }
368
369 static void process_cleanup(struct ps_prochandle* ph) {
370 detach_all_pids(ph);
371 }
372
373 static ps_prochandle_ops process_ops = {
374 .release= process_cleanup,
375 .p_pread= process_read_data,
376 .p_pwrite= process_write_data,
377 .get_lwp_regs= process_get_lwp_regs
378 };
379
380 // attach to the process. One and only one exposed stuff
381 struct ps_prochandle* Pgrab(pid_t pid, char* err_buf, size_t err_buf_len) {
382 struct ps_prochandle* ph = NULL;
383 thread_info* thr = NULL;
384
385 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
386 snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle");
387 print_debug("%s\n", err_buf);
388 return NULL;
389 }
390
391 if (ptrace_attach(pid, err_buf, err_buf_len) != true) {
392 free(ph);
393 return NULL;
394 }
395
396 // initialize ps_prochandle
397 ph->pid = pid;
398
399 // initialize vtable
400 ph->ops = &process_ops;
401
402 // read library info and symbol tables, must do this before attaching threads,
403 // as the symbols in the pthread library will be used to figure out
404 // the list of threads within the same process.
405 read_lib_info(ph);
406
407 #ifdef INCLUDE_SA_ATTACH
408 // read thread info
409 read_thread_info(ph, add_new_thread);
410
411 // attach to the threads
412 thr = ph->threads;
413 while (thr) {
414 // don't attach to the main thread again
415 if (pid != thr->lwp_id && ptrace_attach(thr->lwp_id, err_buf, err_buf_len) != true) {
416 // even if one attach fails, we get return NULL
417 Prelease(ph);
418 return NULL;
419 }
420 thr = thr->next;
421 }
422 #else
423 DIR *dir = NULL;
424 struct dirent *ent = NULL;
425 char taskpath[80];
426
427 // Find the lwpids to attach to by traversing the /proc/<pid>/task/ directory,
428 // and attach to those.
429 snprintf (taskpath, sizeof (taskpath), "/proc/%ld/task", (unsigned long) pid);
430 if ((dir = opendir(taskpath)) != NULL) {
431 while ((ent = readdir (dir)) != NULL) {
432 unsigned long lwp;
433
434 if ((lwp = strtoul (ent->d_name, NULL, 10)) != 0) {
435 add_new_thread (ph, 0, lwp);
436
437 // Don't attach to the main thread again
438 if (lwp == (unsigned long) pid) {
439 continue;
440 }
441
442 if (ptrace_attach(lwp, err_buf, err_buf_len) != true) {
443 Prelease(ph);
444 closedir (dir);
445 return NULL;
446 }
447 }
448 }
449 } else {
450 print_debug("Could not open /proc/%ld/task.\n", (unsigned long) pid);
451 Prelease(ph);
452 return NULL;
453 }
454
455 closedir (dir);
456 #endif
457 return ph;
458 }