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