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) { 219 if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) { 220 print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid); 221 return false; 222 } else { 223 return ptrace_waitpid(pid); 224 } 225 } 226 227 // ------------------------------------------------------- 228 // functions for obtaining library information 229 // ------------------------------------------------------- 230 231 /* 232 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring 233 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_. 234 * RETURN VALUE: total number of substrings (always <= _n_) 235 * NOTE: string _str_ is modified if _delim_!=_new_delim_ 236 */ 237 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim) 238 { 239 int i; 240 for(i = 0; i < n; i++) ptrs[i] = NULL; 241 if (str == NULL || n < 1 ) return 0; 242 243 i = 0; 244 245 // skipping leading blanks 246 while(*str&&*str==delim) str++; 247 248 while(*str&&i<n){ 249 ptrs[i++] = str; 250 while(*str&&*str!=delim) str++; 251 while(*str&&*str==delim) *(str++) = new_delim; 252 } 253 254 return i; 255 } 256 257 /* 258 * fgets without storing '\n' at the end of the string 259 */ 260 static char * fgets_no_cr(char * buf, int n, FILE *fp) 261 { 262 char * rslt = fgets(buf, n, fp); 263 if (rslt && buf && *buf){ 264 char *p = strchr(buf, '\0'); 265 if (*--p=='\n') *p='\0'; 266 } 267 return rslt; 268 } 269 270 // callback for read_thread_info 271 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) { 272 return add_thread_info(ph, pthread_id, lwp_id) != NULL; 273 } 274 275 static bool read_lib_info(struct ps_prochandle* ph) { 276 char fname[32]; 277 char buf[PATH_MAX]; 278 FILE *fp = NULL; 279 280 sprintf(fname, "/proc/%d/maps", ph->pid); 281 fp = fopen(fname, "r"); 282 if (fp == NULL) { 283 print_debug("can't open /proc/%d/maps file\n", ph->pid); 284 return false; 285 } 286 287 while(fgets_no_cr(buf, PATH_MAX, fp)){ 288 char * word[7]; 289 int nwords = split_n_str(buf, 7, word, ' ', '\0'); 290 291 if (nwords < 6) { 292 // not a shared library entry. ignore. 293 continue; 294 } 295 296 // SA does not handle the lines with patterns: 297 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc. 298 if (word[5][0] == '[') { 299 // not a shared library entry. ignore. 300 continue; 301 } 302 303 if (nwords > 6) { 304 // prelink altered mapfile when the program is running. 305 // Entries like one below have to be skipped 306 // /lib64/libc-2.15.so (deleted) 307 // SO name in entries like one below have to be stripped. 308 // /lib64/libpthread-2.15.so.#prelink#.EECVts 309 char *s = strstr(word[5],".#prelink#"); 310 if (s == NULL) { 311 // No prelink keyword. skip deleted library 312 print_debug("skip shared object %s deleted by prelink\n", word[5]); 313 continue; 314 } 315 316 // Fall through 317 print_debug("rectifying shared object name %s changed by prelink\n", word[5]); 318 *s = 0; 319 } 320 321 if (find_lib(ph, word[5]) == false) { 322 intptr_t base; 323 lib_info* lib; 324 #ifdef _LP64 325 sscanf(word[0], "%lx", &base); 326 #else 327 sscanf(word[0], "%x", &base); 328 #endif 329 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL) 330 continue; // ignore, add_lib_info prints error 331 332 // we don't need to keep the library open, symtab is already 333 // built. Only for core dump we need to keep the fd open. 334 close(lib->fd); 335 lib->fd = -1; 336 } 337 } 338 fclose(fp); 339 return true; 340 } 341 342 // detach a given pid 343 static bool ptrace_detach(pid_t pid) { 344 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) { 345 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid); 346 return false; 347 } else { 348 return true; 349 } 350 } 351 352 // detach all pids of a ps_prochandle 353 static void detach_all_pids(struct ps_prochandle* ph) { 354 thread_info* thr = ph->threads; 355 while (thr) { 356 ptrace_detach(thr->lwp_id); 357 thr = thr->next; 358 } 359 } 360 361 static void process_cleanup(struct ps_prochandle* ph) { 362 detach_all_pids(ph); 363 } 364 365 static ps_prochandle_ops process_ops = { 366 .release= process_cleanup, 367 .p_pread= process_read_data, 368 .p_pwrite= process_write_data, 369 .get_lwp_regs= process_get_lwp_regs 370 }; 371 372 // attach to the process. One and only one exposed stuff 373 struct ps_prochandle* Pgrab(pid_t pid) { 374 struct ps_prochandle* ph = NULL; 375 thread_info* thr = NULL; 376 377 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) { 378 print_debug("can't allocate memory for ps_prochandle\n"); 379 return NULL; 380 } 381 382 if (ptrace_attach(pid) != true) { 383 free(ph); 384 return NULL; 385 } 386 387 // initialize ps_prochandle 388 ph->pid = pid; 389 390 // initialize vtable 391 ph->ops = &process_ops; 392 393 // read library info and symbol tables, must do this before attaching threads, 394 // as the symbols in the pthread library will be used to figure out 395 // the list of threads within the same process. 396 read_lib_info(ph); 397 398 // read thread info 399 read_thread_info(ph, add_new_thread); 400 401 // attach to the threads 402 thr = ph->threads; 403 while (thr) { 404 // don't attach to the main thread again 405 if (ph->pid != thr->lwp_id && ptrace_attach(thr->lwp_id) != true) { 406 // even if one attach fails, we get return NULL 407 Prelease(ph); 408 return NULL; 409 } 410 thr = thr->next; 411 } 412 return ph; 413 }