1 /*
2 * Copyright (c) 2003, 2010, 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 <limits.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <errno.h>
30 #include <sys/types.h>
31 #include <sys/wait.h>
32 #include <sys/ptrace.h>
33 #include <sys/param.h>
34 #include <sys/user.h>
35 #include <elf.h>
36 #include <sys/elf_common.h>
37 #include <sys/link_elf.h>
38 #include <libutil.h>
39 #include "libproc_impl.h"
40 #include "elfmacros.h"
41
42 // This file has the libproc implementation specific to live process
43 // For core files, refer to ps_core.c
44
45 static inline uintptr_t align(uintptr_t ptr, size_t size) {
46 return (ptr & ~(size - 1));
47 }
48
49 // ---------------------------------------------
50 // ptrace functions
51 // ---------------------------------------------
52
53 // read "size" bytes of data from "addr" within the target process.
54 // unlike the standard ptrace() function, process_read_data() can handle
55 // unaligned address - alignment check, if required, should be done
56 // before calling process_read_data.
57
58 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
59 int rslt;
60 size_t i, words;
61 uintptr_t end_addr = addr + size;
62 uintptr_t aligned_addr = align(addr, sizeof(int));
63
64 if (aligned_addr != addr) {
65 char *ptr = (char *)&rslt;
66 errno = 0;
67 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
68 if (errno) {
69 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
70 return false;
71 }
72 for (; aligned_addr != addr; aligned_addr++, ptr++);
73 for (; ((intptr_t)aligned_addr % sizeof(int)) && aligned_addr < end_addr;
74 aligned_addr++)
75 *(buf++) = *(ptr++);
76 }
77
78 words = (end_addr - aligned_addr) / sizeof(int);
79
80 // assert((intptr_t)aligned_addr % sizeof(int) == 0);
81 for (i = 0; i < words; i++) {
82 errno = 0;
83 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
84 if (errno) {
85 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
86 return false;
87 }
88 *(int *)buf = rslt;
89 buf += sizeof(int);
90 aligned_addr += sizeof(int);
91 }
92
93 if (aligned_addr != end_addr) {
94 char *ptr = (char *)&rslt;
95 errno = 0;
96 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
97 if (errno) {
98 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
99 return false;
100 }
101 for (; aligned_addr != end_addr; aligned_addr++)
102 *(buf++) = *(ptr++);
103 }
104 return true;
105 }
106
107 // null implementation for write
108 static bool process_write_data(struct ps_prochandle* ph,
109 uintptr_t addr, const char *buf , size_t size) {
110 return false;
111 }
112
113 // "user" should be a pointer to a reg
114 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct reg *user) {
115 // we have already attached to all thread 'pid's, just use ptrace call
116 // to get regset now. Note that we don't cache regset upfront for processes.
117 if (ptrace(PT_GETREGS, pid, (caddr_t) user, 0) < 0) {
118 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
119 return false;
120 }
121 return true;
122 }
123
124 // fill in ptrace_lwpinfo for lid
125 static bool process_get_lwp_info(struct ps_prochandle *ph, lwpid_t lwp_id, void *linfo) {
126 errno = 0;
127 ptrace(PT_LWPINFO, lwp_id, linfo, sizeof(struct ptrace_lwpinfo));
128
129 return (errno == 0)? true: false;
130 }
131
132 // attach to a process/thread specified by "pid"
133 static bool ptrace_attach(pid_t pid) {
134 if (ptrace(PT_ATTACH, pid, NULL, 0) < 0) {
135 print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid);
136 return false;
137 } else {
138 int ret;
139 int status;
140 do {
141 // Wait for debuggee to stop.
142 ret = waitpid(pid, &status, 0);
143 if (ret >= 0) {
144 if (WIFSTOPPED(status)) {
145 // Debuggee stopped.
146 return true;
147 } else {
148 print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
149 return false;
150 }
151 } else {
152 switch (errno) {
153 case EINTR:
154 continue;
155 break;
156 case ECHILD:
157 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
158 break;
159 case EINVAL:
160 print_debug("waitpid() failed. Invalid options argument.\n");
161 break;
162 default:
163 print_debug("waitpid() failed. Unexpected error %d\n",errno);
164 }
165 return false;
166 }
167 } while(true);
168 }
169 }
170
171 // -------------------------------------------------------
172 // functions for obtaining library information
173 // -------------------------------------------------------
174
175 // callback for read_thread_info
176 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
177 return add_thread_info(ph, pthread_id, lwp_id) != NULL;
178 }
179
180 #if defined(__FreeBSD__) && __FreeBSD_version < 701000
181 /*
182 * TEXT_START_ADDR from binutils/ld/emulparams/<arch_spec>.sh
183 * Not the most robust but good enough.
184 */
185
186 #if defined(amd64) || defined(x86_64)
187 #define TEXT_START_ADDR 0x400000
188 #elif defined(i386)
189 #define TEXT_START_ADDR 0x8048000
190 #else
191 #error TEXT_START_ADDR not defined
192 #endif
193
194 #define BUF_SIZE (PATH_MAX + NAME_MAX + 1)
195
196 uintptr_t linkmap_addr(struct ps_prochandle *ph) {
197 uintptr_t ehdr_addr, phdr_addr, dyn_addr, dmap_addr, lmap_addr;
198 ELF_EHDR ehdr;
199 ELF_PHDR *phdrs, *phdr;
200 ELF_DYN *dyns, *dyn;
201 struct r_debug dmap;
202 unsigned long hdrs_size;
203 unsigned int i;
204
205 /* read ELF_EHDR at TEXT_START_ADDR and validate */
206
207 ehdr_addr = (uintptr_t)TEXT_START_ADDR;
208
209 if (process_read_data(ph, ehdr_addr, (char *)&ehdr, sizeof(ehdr)) != true) {
210 print_debug("process_read_data failed for ehdr_addr %p\n", ehdr_addr);
211 return (0);
212 }
213
214 if (!IS_ELF(ehdr) ||
215 ehdr.e_ident[EI_CLASS] != ELF_TARG_CLASS ||
216 ehdr.e_ident[EI_DATA] != ELF_TARG_DATA ||
217 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
218 ehdr.e_phentsize != sizeof(ELF_PHDR) ||
219 ehdr.e_version != ELF_TARG_VER ||
220 ehdr.e_machine != ELF_TARG_MACH) {
221 print_debug("not an ELF_EHDR at %p\n", ehdr_addr);
222 return (0);
223 }
224
225 /* allocate space for all ELF_PHDR's and read */
226
227 phdr_addr = ehdr_addr + ehdr.e_phoff;
228 hdrs_size = ehdr.e_phnum * sizeof(ELF_PHDR);
229
230 if ((phdrs = malloc(hdrs_size)) == NULL)
231 return (0);
232
233 if (process_read_data(ph, phdr_addr, (char *)phdrs, hdrs_size) != true) {
234 print_debug("process_read_data failed for phdr_addr %p\n", phdr_addr);
235 return (0);
236 }
237
238 /* find PT_DYNAMIC section */
239
240 for (i = 0, phdr = phdrs; i < ehdr.e_phnum; i++, phdr++) {
241 if (phdr->p_type == PT_DYNAMIC)
242 break;
243 }
244
245 if (i >= ehdr.e_phnum) {
246 print_debug("PT_DYNAMIC section not found!\n");
247 free(phdrs);
248 return (0);
249 }
250
251 /* allocate space and read in ELF_DYN headers */
252
253 dyn_addr = phdr->p_vaddr;
254 hdrs_size = phdr->p_memsz;
255 free(phdrs);
256
257 if ((dyns = malloc(hdrs_size)) == NULL)
258 return (0);
259
260 if (process_read_data(ph, dyn_addr, (char *)dyns, hdrs_size) != true) {
261 print_debug("process_read_data failed for dyn_addr %p\n", dyn_addr);
262 free(dyns);
263 return (0);
264 }
265
266 /* find DT_DEBUG */
267
268 dyn = dyns;
269 while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) {
270 dyn++;
271 }
272
273 if (dyn->d_tag != DT_DEBUG) {
274 print_debug("failed to find DT_DEBUG\n");
275 free(dyns);
276 return (0);
277 }
278
279 /* read struct r_debug into dmap */
280
281 dmap_addr = (uintptr_t)dyn->d_un.d_ptr;
282 free(dyns);
283
284 if (process_read_data(ph, dmap_addr, (char *)&dmap, sizeof(dmap)) != true) {
285 print_debug("process_read_data failed for dmap_addr %p\n", dmap_addr);
286 return (0);
287 }
288
289 lmap_addr = (uintptr_t)dmap.r_map;
290
291 return (lmap_addr);
292 }
293 #endif // __FreeBSD__ && __FreeBSD_version < 701000
294
295 static bool read_lib_info(struct ps_prochandle* ph) {
296 #if defined(__FreeBSD__) && __FreeBSD_version >= 701000
297 struct kinfo_vmentry *freep, *kve;
298 int i, cnt;
299
300 freep = kinfo_getvmmap(ph->pid, &cnt);
301 if (freep == NULL) {
302 print_debug("can't get vm map for pid\n", ph->pid);
303 return false;
304 }
305
306 for (i = 0; i < cnt; i++) {
307 kve = &freep[i];
308 if ((kve->kve_flags & KVME_FLAG_COW) &&
309 kve->kve_path != NULL &&
310 strlen(kve->kve_path) > 0) {
311
312 if (find_lib(ph, kve->kve_path) == false) {
313 lib_info* lib;
314 if ((lib = add_lib_info(ph, kve->kve_path,
315 (uintptr_t) kve->kve_start)) == NULL)
316 continue; // ignore, add_lib_info prints error
317
318 // we don't need to keep the library open, symtab is already
319 // built. Only for core dump we need to keep the fd open.
320 close(lib->fd);
321 lib->fd = -1;
322 }
323 }
324 }
325
326 free(freep);
327
328 return true;
329 #else
330 char *l_name;
331 struct link_map *lmap;
332 uintptr_t lmap_addr;
333
334 if ((l_name = malloc(BUF_SIZE)) == NULL)
335 return false;
336
337 if ((lmap = malloc(sizeof(*lmap))) == NULL) {
338 free(l_name);
339 return false;
340 }
341
342 lmap_addr = linkmap_addr(ph);
343
344 if (lmap_addr == 0) {
345 free(l_name);
346 free(lmap);
347 return false;
348 }
349
350 do {
351 if (process_read_data(ph, lmap_addr, (char *)lmap, sizeof(*lmap)) != true) {
352 print_debug("process_read_data failed for lmap_addr %p\n", lmap_addr);
353 free (l_name);
354 free (lmap);
355 return false;
356 }
357
358 if (process_read_data(ph, (uintptr_t)lmap->l_name, l_name,
359 BUF_SIZE) != true) {
360 print_debug("process_read_data failed for lmap->l_name %p\n",
361 lmap->l_name);
362 free (l_name);
363 free (lmap);
364 return false;
365 }
366
367 if (find_lib(ph, l_name) == false) {
368 lib_info* lib;
369 if ((lib = add_lib_info(ph, l_name,
370 (uintptr_t) lmap->l_addr)) == NULL)
371 continue; // ignore, add_lib_info prints error
372
373 // we don't need to keep the library open, symtab is already
374 // built. Only for core dump we need to keep the fd open.
375 close(lib->fd);
376 lib->fd = -1;
377 }
378 lmap_addr = (uintptr_t)lmap->l_next;
379 } while (lmap->l_next != NULL);
380
381 free (l_name);
382 free (lmap);
383
384 return true;
385 #endif
386 }
387
388 // detach a given pid
389 static bool ptrace_detach(pid_t pid) {
390 if (pid && ptrace(PT_DETACH, pid, (caddr_t)1, 0) < 0) {
391 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
392 return false;
393 } else {
394 return true;
395 }
396 }
397
398 static void process_cleanup(struct ps_prochandle* ph) {
399 ptrace_detach(ph->pid);
400 }
401
402 static ps_prochandle_ops process_ops = {
403 .release= process_cleanup,
404 .p_pread= process_read_data,
405 .p_pwrite= process_write_data,
406 .get_lwp_regs= process_get_lwp_regs,
407 .get_lwp_info= process_get_lwp_info
408 };
409
410 // attach to the process. One and only one exposed stuff
411 struct ps_prochandle* Pgrab(pid_t pid) {
412 struct ps_prochandle* ph = NULL;
413 thread_info* thr = NULL;
414
415 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
416 print_debug("can't allocate memory for ps_prochandle\n");
417 return NULL;
418 }
419
420 if (ptrace_attach(pid) != true) {
421 free(ph);
422 return NULL;
423 }
424
425 // initialize ps_prochandle
426 ph->pid = pid;
427
428 // initialize vtable
429 ph->ops = &process_ops;
430
431 // read library info and symbol tables, must do this before attaching threads,
432 // as the symbols in the pthread library will be used to figure out
433 // the list of threads within the same process.
434 if (read_lib_info(ph) != true) {
435 ptrace_detach(pid);
436 free(ph);
437 return NULL;
438 }
439
440 // read thread info
441 read_thread_info(ph, add_new_thread);
442
443 return ph;
444 }