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 #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 if (strerror_r(errno, buf, sizeof(buf) == 0)) {
222 snprintf(err_buf, err_buf_len,
223 "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, buf);
224 print_debug("%s\n", err_buf);
225 }
226 return false;
227 } else {
228 return ptrace_waitpid(pid);
229 }
230 }
231
232 // -------------------------------------------------------
233 // functions for obtaining library information
234 // -------------------------------------------------------
235
236 /*
237 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring
238 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_.
239 * RETURN VALUE: total number of substrings (always <= _n_)
240 * NOTE: string _str_ is modified if _delim_!=_new_delim_
241 */
242 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim)
243 {
244 int i;
245 for(i = 0; i < n; i++) ptrs[i] = NULL;
246 if (str == NULL || n < 1 ) return 0;
247
248 i = 0;
249
250 // skipping leading blanks
251 while(*str&&*str==delim) str++;
252
253 while(*str&&i<n){
254 ptrs[i++] = str;
255 while(*str&&*str!=delim) str++;
256 while(*str&&*str==delim) *(str++) = new_delim;
257 }
258
259 return i;
260 }
261
262 /*
263 * fgets without storing '\n' at the end of the string
264 */
265 static char * fgets_no_cr(char * buf, int n, FILE *fp)
266 {
267 char * rslt = fgets(buf, n, fp);
268 if (rslt && buf && *buf){
269 char *p = strchr(buf, '\0');
270 if (*--p=='\n') *p='\0';
271 }
272 return rslt;
273 }
274
275 // callback for read_thread_info
276 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
277 return add_thread_info(ph, pthread_id, lwp_id) != NULL;
278 }
279
280 static bool read_lib_info(struct ps_prochandle* ph) {
281 char fname[32];
282 char buf[PATH_MAX];
283 FILE *fp = NULL;
284
285 sprintf(fname, "/proc/%d/maps", ph->pid);
286 fp = fopen(fname, "r");
287 if (fp == NULL) {
288 print_debug("can't open /proc/%d/maps file\n", ph->pid);
289 return false;
290 }
291
292 while(fgets_no_cr(buf, PATH_MAX, fp)){
293 char * word[7];
294 int nwords = split_n_str(buf, 7, word, ' ', '\0');
295
296 if (nwords < 6) {
297 // not a shared library entry. ignore.
298 continue;
299 }
300
301 // SA does not handle the lines with patterns:
302 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc.
303 if (word[5][0] == '[') {
304 // not a shared library entry. ignore.
305 continue;
306 }
307
308 if (nwords > 6) {
309 // prelink altered mapfile when the program is running.
310 // Entries like one below have to be skipped
311 // /lib64/libc-2.15.so (deleted)
312 // SO name in entries like one below have to be stripped.
313 // /lib64/libpthread-2.15.so.#prelink#.EECVts
314 char *s = strstr(word[5],".#prelink#");
315 if (s == NULL) {
316 // No prelink keyword. skip deleted library
317 print_debug("skip shared object %s deleted by prelink\n", word[5]);
318 continue;
319 }
320
321 // Fall through
322 print_debug("rectifying shared object name %s changed by prelink\n", word[5]);
323 *s = 0;
324 }
325
326 if (find_lib(ph, word[5]) == false) {
327 intptr_t base;
328 lib_info* lib;
329 #ifdef _LP64
330 sscanf(word[0], "%lx", &base);
331 #else
332 sscanf(word[0], "%x", &base);
333 #endif
334 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL)
335 continue; // ignore, add_lib_info prints error
336
337 // we don't need to keep the library open, symtab is already
338 // built. Only for core dump we need to keep the fd open.
339 close(lib->fd);
340 lib->fd = -1;
341 }
342 }
343 fclose(fp);
344 return true;
345 }
346
347 // detach a given pid
348 static bool ptrace_detach(pid_t pid) {
349 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) {
350 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
351 return false;
352 } else {
353 return true;
354 }
355 }
356
357 // detach all pids of a ps_prochandle
358 static void detach_all_pids(struct ps_prochandle* ph) {
359 thread_info* thr = ph->threads;
360 while (thr) {
361 ptrace_detach(thr->lwp_id);
362 thr = thr->next;
363 }
364 }
365
366 static void process_cleanup(struct ps_prochandle* ph) {
367 detach_all_pids(ph);
368 }
369
370 static ps_prochandle_ops process_ops = {
371 .release= process_cleanup,
372 .p_pread= process_read_data,
373 .p_pwrite= process_write_data,
374 .get_lwp_regs= process_get_lwp_regs
375 };
376
377 // attach to the process. One and only one exposed stuff
378 struct ps_prochandle* Pgrab(pid_t pid, char* err_buf, size_t err_buf_len) {
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 read_thread_info(ph, add_new_thread);
406
407 // attach to the threads
408 thr = ph->threads;
409 while (thr) {
410 // don't attach to the main thread again
411 if (pid != thr->lwp_id && ptrace_attach(thr->lwp_id, err_buf, err_buf_len) != true) {
412 // even if one attach fails, we get return NULL
413 Prelease(ph);
414 return NULL;
415 }
416 thr = thr->next;
417 }
418 return ph;
419 }