1 /*
2 * Copyright (c) 2003, 2018, 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 <sys/types.h>
33 #include <sys/wait.h>
34 #include <sys/ptrace.h>
35 #include <sys/uio.h>
36 #include "libproc_impl.h"
37
38 #if defined(x86_64) && !defined(amd64)
39 #define amd64 1
40 #endif
41
42 #ifndef __WALL
43 #define __WALL 0x40000000 // Copied from /usr/include/linux/wait.h
44 #endif
45
46 // This file has the libproc implementation specific to live process
47 // For core files, refer to ps_core.c
48
49 static inline uintptr_t align(uintptr_t ptr, size_t size) {
50 return (ptr & ~(size - 1));
51 }
52
53 // ---------------------------------------------
54 // ptrace functions
55 // ---------------------------------------------
56
57 // read "size" bytes of data from "addr" within the target process.
58 // unlike the standard ptrace() function, process_read_data() can handle
59 // unaligned address - alignment check, if required, should be done
60 // before calling process_read_data.
61
62 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
63 long rslt;
64 size_t i, words;
65 uintptr_t end_addr = addr + size;
66 uintptr_t aligned_addr = align(addr, sizeof(long));
67
68 if (aligned_addr != addr) {
69 char *ptr = (char *)&rslt;
70 errno = 0;
71 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
72 if (errno) {
73 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
74 return false;
75 }
76 for (; aligned_addr != addr; aligned_addr++, ptr++);
77 for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr;
78 aligned_addr++)
79 *(buf++) = *(ptr++);
80 }
81
82 words = (end_addr - aligned_addr) / sizeof(long);
83
84 // assert((intptr_t)aligned_addr % sizeof(long) == 0);
85 for (i = 0; i < words; i++) {
86 errno = 0;
87 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
88 if (errno) {
89 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
90 return false;
91 }
92 *(long *)buf = rslt;
93 buf += sizeof(long);
94 aligned_addr += sizeof(long);
95 }
96
97 if (aligned_addr != end_addr) {
98 char *ptr = (char *)&rslt;
99 errno = 0;
100 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0);
101 if (errno) {
102 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr);
103 return false;
104 }
105 for (; aligned_addr != end_addr; aligned_addr++)
106 *(buf++) = *(ptr++);
107 }
108 return true;
109 }
110
111 // null implementation for write
112 static bool process_write_data(struct ps_prochandle* ph,
113 uintptr_t addr, const char *buf , size_t size) {
114 return false;
115 }
116
117 // "user" should be a pointer to a user_regs_struct
118 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) {
119 // we have already attached to all thread 'pid's, just use ptrace call
120 // to get regset now. Note that we don't cache regset upfront for processes.
121 // Linux on x86 and sparc are different. On x86 ptrace(PTRACE_GETREGS, ...)
122 // uses pointer from 4th argument and ignores 3rd argument. On sparc it uses
123 // pointer from 3rd argument and ignores 4th argument
124 #if defined(sparc) || defined(sparcv9)
125 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)
126 #else
127 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
128 #endif
129
130 #if defined(_LP64) && defined(PTRACE_GETREGS64)
131 #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
132 #elif defined(PTRACE_GETREGS)
133 #define PTRACE_GETREGS_REQ PTRACE_GETREGS
134 #elif defined(PT_GETREGS)
135 #define PTRACE_GETREGS_REQ PT_GETREGS
136 #endif
137
138 #ifdef PTRACE_GETREGS_REQ
139 if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) {
140 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
141 return false;
142 }
143 return true;
144 #elif defined(PTRACE_GETREGSET)
145 struct iovec iov;
146 iov.iov_base = user;
147 iov.iov_len = sizeof(*user);
148 if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void*) &iov) < 0) {
149 print_debug("ptrace(PTRACE_GETREGSET, ...) failed for lwp %d\n", pid);
150 return false;
151 }
152 return true;
153 #else
154 print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n");
155 return false;
156 #endif
157
158 }
159
160 static bool ptrace_continue(pid_t pid, int signal) {
161 // pass the signal to the process so we don't swallow it
162 if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
163 print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
164 return false;
165 }
166 return true;
167 }
168
169 // waits until the ATTACH has stopped the process
170 // by signal SIGSTOP
171 static bool ptrace_waitpid(pid_t pid) {
172 int ret;
173 int status;
174 while (true) {
175 // Wait for debuggee to stop.
176 ret = waitpid(pid, &status, 0);
177 if (ret == -1 && errno == ECHILD) {
178 // try cloned process.
179 ret = waitpid(pid, &status, __WALL);
180 }
181 if (ret >= 0) {
182 if (WIFSTOPPED(status)) {
183 // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
184 // will still be pending and delivered when the process is DETACHED and the process
185 // will go to sleep.
186 if (WSTOPSIG(status) == SIGSTOP) {
187 // Debuggee stopped by SIGSTOP.
188 return true;
189 }
190 if (!ptrace_continue(pid, WSTOPSIG(status))) {
191 print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
192 return false;
193 }
194 } else {
195 print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
196 return false;
197 }
198 } else {
199 switch (errno) {
200 case EINTR:
201 continue;
202 break;
203 case ECHILD:
204 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
205 break;
206 case EINVAL:
207 print_debug("waitpid() failed. Invalid options argument.\n");
208 break;
209 default:
210 print_debug("waitpid() failed. Unexpected error %d\n",errno);
211 break;
212 }
213 return false;
214 }
215 }
216 }
217
218 // attach to a process/thread specified by "pid"
219 static bool ptrace_attach(pid_t pid, char* err_buf, size_t err_buf_len) {
220 if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) {
221 char buf[200];
222 char* msg = strerror_r(errno, buf, sizeof(buf));
223 snprintf(err_buf, err_buf_len, "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, msg);
224 print_debug("%s\n", err_buf);
225 return false;
226 } else {
227 return ptrace_waitpid(pid);
228 }
229 }
230
231 // -------------------------------------------------------
232 // functions for obtaining library information
233 // -------------------------------------------------------
234
235 /*
236 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring
237 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.
238 * RETURN VALUE: total number of substrings (always <= _n_)
239 * NOTE: string _str_ is modified if _delim_!=_new_delim_
240 */
241 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)
242 {
243 int i;
244 for(i = 0; i < n; i++) ptrs[i] = NULL;
245 if (str == NULL || n < 1 ) return 0;
246
247 i = 0;
248
249 // skipping leading blanks
250 while(*str&&*str==delim) str++;
251
252 while(*str&&i<n){
253 ptrs[i++] = str;
254 while(*str&&*str!=delim) str++;
255 while(*str&&*str==delim) *(str++) = new_delim;
256 }
257
258 return i;
259 }
260
261 /*
262 * fgets without storing '\n' at the end of the string
263 */
264 static char * fgets_no_cr(char * buf, int n, FILE *fp)
265 {
266 char * rslt = fgets(buf, n, fp);
267 if (rslt && buf && *buf){
268 char *p = strchr(buf, '\0');
269 if (*--p=='\n') *p='\0';
270 }
271 return rslt;
272 }
273
274 // callback for read_thread_info
275 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
276 return add_thread_info(ph, pthread_id, lwp_id) != NULL;
277 }
278
279 static bool read_lib_info(struct ps_prochandle* ph) {
280 char fname[32];
281 char buf[PATH_MAX];
282 FILE *fp = NULL;
283
284 sprintf(fname, "/proc/%d/maps", ph->pid);
285 fp = fopen(fname, "r");
286 if (fp == NULL) {
287 print_debug("can't open /proc/%d/maps file\n", ph->pid);
288 return false;
289 }
290
291 while(fgets_no_cr(buf, PATH_MAX, fp)){
292 char * word[7];
293 int nwords = split_n_str(buf, 7, word, ' ', '\0');
294
295 if (nwords < 6) {
296 // not a shared library entry. ignore.
297 continue;
298 }
299
300 // SA does not handle the lines with patterns:
301 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc.
302 if (word[5][0] == '[') {
303 // not a shared library entry. ignore.
304 continue;
305 }
306
307 if (nwords > 6) {
308 // prelink altered mapfile when the program is running.
309 // Entries like one below have to be skipped
310 // /lib64/libc-2.15.so (deleted)
311 // SO name in entries like one below have to be stripped.
312 // /lib64/libpthread-2.15.so.#prelink#.EECVts
313 char *s = strstr(word[5],".#prelink#");
314 if (s == NULL) {
315 // No prelink keyword. skip deleted library
316 print_debug("skip shared object %s deleted by prelink\n", word[5]);
317 continue;
318 }
319
320 // Fall through
321 print_debug("rectifying shared object name %s changed by prelink\n", word[5]);
322 *s = 0;
323 }
324
325 if (find_lib(ph, word[5]) == false) {
326 intptr_t base;
327 lib_info* lib;
328 #ifdef _LP64
329 sscanf(word[0], "%lx", &base);
330 #else
331 sscanf(word[0], "%x", &base);
332 #endif
333 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)
334 continue; // ignore, add_lib_info prints error
335
336 // we don't need to keep the library open, symtab is already
337 // built. Only for core dump we need to keep the fd open.
338 close(lib->fd);
339 lib->fd = -1;
340 }
341 }
342 fclose(fp);
343 return true;
344 }
345
346 // detach a given pid
347 static bool ptrace_detach(pid_t pid) {
348 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {
349 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
350 return false;
351 } else {
352 return true;
353 }
354 }
355
356 // detach all pids of a ps_prochandle
357 static void detach_all_pids(struct ps_prochandle* ph) {
358 thread_info* thr = ph->threads;
359 while (thr) {
360 ptrace_detach(thr->lwp_id);
361 thr = thr->next;
362 }
363 }
364
365 static void process_cleanup(struct ps_prochandle* ph) {
366 detach_all_pids(ph);
367 }
368
369 static ps_prochandle_ops process_ops = {
370 .release= process_cleanup,
371 .p_pread= process_read_data,
372 .p_pwrite= process_write_data,
373 .get_lwp_regs= process_get_lwp_regs
374 };
375
376 // attach to the process. One and only one exposed stuff
377 JNIEXPORT struct ps_prochandle* JNICALL
378 Pgrab(pid_t pid, char* err_buf, size_t err_buf_len, bool is_in_container) {
379 struct ps_prochandle* ph = NULL;
380 thread_info* thr = NULL;
381
382 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
383 snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle");
384 print_debug("%s\n", err_buf);
385 return NULL;
386 }
387
388 if (ptrace_attach(pid, err_buf, err_buf_len) != true) {
389 free(ph);
390 return NULL;
391 }
392
393 // initialize ps_prochandle
394 ph->pid = pid;
395
396 // initialize vtable
397 ph->ops = &process_ops;
398
399 // read library info and symbol tables, must do this before attaching threads,
400 // as the symbols in the pthread library will be used to figure out
401 // the list of threads within the same process.
402 read_lib_info(ph);
403
404 // read thread info
405 if (is_in_container) {
406 /*
407 * If the process is running in the container, SA scans all tasks in
408 * /proc/<PID>/task to read all threads info.
409 */
410 char taskpath[PATH_MAX];
411 DIR *dirp;
412 struct dirent *entry;
413
414 snprintf(taskpath, PATH_MAX, "/proc/%d/task", ph->pid);
415 dirp = opendir(taskpath);
416 int lwp_id;
417 while ((entry = readdir(dirp)) != NULL) {
418 if (*entry->d_name == '.') {
419 continue;
420 }
421 lwp_id = atoi(entry->d_name);
422 if (lwp_id == ph->pid) {
423 continue;
424 }
425 add_new_thread(ph, -1, lwp_id);
426 }
427 closedir(dirp);
428 } else {
429 read_thread_info(ph, add_new_thread);
430 }
431
432 // attach to the threads
433 thr = ph->threads;
434 while (thr) {
435 // don't attach to the main thread again
436 if (ph->pid != thr->lwp_id && ptrace_attach(thr->lwp_id, err_buf, err_buf_len) != true) {
437 // even if one attach fails, we get return NULL
438 Prelease(ph);
439 return NULL;
440 }
441 thr = thr->next;
442 }
443 return ph;
444 }