1 /* 2 * Copyright (c) 2003, 2013, 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 struct ps_prochandle* Pgrab(pid_t pid, char* err_buf, size_t err_buf_len) { 377 struct ps_prochandle* ph = NULL; 378 thread_info* thr = NULL; 379 380 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) { 381 snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle"); 382 print_debug("%s\n", err_buf); 383 return NULL; 384 } 385 386 if (ptrace_attach(pid, err_buf, err_buf_len) != true) { 387 free(ph); 388 return NULL; 389 } 390 391 // initialize ps_prochandle 392 ph->pid = pid; 393 394 // initialize vtable 395 ph->ops = &process_ops; 396 397 // read library info and symbol tables, must do this before attaching threads, 398 // as the symbols in the pthread library will be used to figure out 399 // the list of threads within the same process. 400 read_lib_info(ph); 401 402 // read thread info 403 read_thread_info(ph, add_new_thread); 404 405 // attach to the threads 406 thr = ph->threads; 407 while (thr) { 408 // don't attach to the main thread again 409 if (ph->pid != thr->lwp_id && ptrace_attach(thr->lwp_id, err_buf, err_buf_len) != true) { 410 // even if one attach fails, we get return NULL 411 Prelease(ph); 412 return NULL; 413 } 414 thr = thr->next; 415 } 416 return ph; 417 }