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 <dirent.h> 32 #include <ctype.h> 33 #include <sys/types.h> 34 #include <sys/wait.h> 35 #include <sys/ptrace.h> 36 #include <sys/uio.h> 37 #include "libproc_impl.h" 38 39 #if defined(x86_64) && !defined(amd64) 40 #define amd64 1 41 #endif 42 43 #ifndef __WALL 44 #define __WALL 0x40000000 // Copied from /usr/include/linux/wait.h 45 #endif 46 47 // This file has the libproc implementation specific to live process 48 // For core files, refer to ps_core.c 49 50 typedef enum { 51 ATTACH_SUCCESS, 52 ATTACH_FAIL, 53 ATTACH_THREAD_DEAD 54 } attach_state_t; 55 56 static inline uintptr_t align(uintptr_t ptr, size_t size) { 57 return (ptr & ~(size - 1)); 58 } 59 60 // --------------------------------------------- 61 // ptrace functions 62 // --------------------------------------------- 63 64 // read "size" bytes of data from "addr" within the target process. 65 // unlike the standard ptrace() function, process_read_data() can handle 66 // unaligned address - alignment check, if required, should be done 67 // before calling process_read_data. 68 69 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) { 70 long rslt; 71 size_t i, words; 72 uintptr_t end_addr = addr + size; 73 uintptr_t aligned_addr = align(addr, sizeof(long)); 74 75 if (aligned_addr != addr) { 76 char *ptr = (char *)&rslt; 77 errno = 0; 78 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0); 79 if (errno) { 80 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr); 81 return false; 82 } 83 for (; aligned_addr != addr; aligned_addr++, ptr++); 84 for (; ((intptr_t)aligned_addr % sizeof(long)) && aligned_addr < end_addr; 85 aligned_addr++) 86 *(buf++) = *(ptr++); 87 } 88 89 words = (end_addr - aligned_addr) / sizeof(long); 90 91 // assert((intptr_t)aligned_addr % sizeof(long) == 0); 92 for (i = 0; i < words; i++) { 93 errno = 0; 94 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0); 95 if (errno) { 96 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr); 97 return false; 98 } 99 *(long *)buf = rslt; 100 buf += sizeof(long); 101 aligned_addr += sizeof(long); 102 } 103 104 if (aligned_addr != end_addr) { 105 char *ptr = (char *)&rslt; 106 errno = 0; 107 rslt = ptrace(PTRACE_PEEKDATA, ph->pid, aligned_addr, 0); 108 if (errno) { 109 print_debug("ptrace(PTRACE_PEEKDATA, ..) failed for %d bytes @ %lx\n", size, addr); 110 return false; 111 } 112 for (; aligned_addr != end_addr; aligned_addr++) 113 *(buf++) = *(ptr++); 114 } 115 return true; 116 } 117 118 // null implementation for write 119 static bool process_write_data(struct ps_prochandle* ph, 120 uintptr_t addr, const char *buf , size_t size) { 121 return false; 122 } 123 124 // "user" should be a pointer to a user_regs_struct 125 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct user_regs_struct *user) { 126 // we have already attached to all thread 'pid's, just use ptrace call 127 // to get regset now. Note that we don't cache regset upfront for processes. 128 // Linux on x86 and sparc are different. On x86 ptrace(PTRACE_GETREGS, ...) 129 // uses pointer from 4th argument and ignores 3rd argument. On sparc it uses 130 // pointer from 3rd argument and ignores 4th argument 131 #if defined(sparc) || defined(sparcv9) 132 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data) 133 #else 134 #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr) 135 #endif 136 137 #if defined(_LP64) && defined(PTRACE_GETREGS64) 138 #define PTRACE_GETREGS_REQ PTRACE_GETREGS64 139 #elif defined(PTRACE_GETREGS) 140 #define PTRACE_GETREGS_REQ PTRACE_GETREGS 141 #elif defined(PT_GETREGS) 142 #define PTRACE_GETREGS_REQ PT_GETREGS 143 #endif 144 145 #ifdef PTRACE_GETREGS_REQ 146 if (ptrace_getregs(PTRACE_GETREGS_REQ, pid, user, NULL) < 0) { 147 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid); 148 return false; 149 } 150 return true; 151 #elif defined(PTRACE_GETREGSET) 152 struct iovec iov; 153 iov.iov_base = user; 154 iov.iov_len = sizeof(*user); 155 if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void*) &iov) < 0) { 156 print_debug("ptrace(PTRACE_GETREGSET, ...) failed for lwp %d\n", pid); 157 return false; 158 } 159 return true; 160 #else 161 print_debug("ptrace(PTRACE_GETREGS, ...) not supported\n"); 162 return false; 163 #endif 164 165 } 166 167 static bool ptrace_continue(pid_t pid, int signal) { 168 // pass the signal to the process so we don't swallow it 169 if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) { 170 print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid); 171 return false; 172 } 173 return true; 174 } 175 176 // waits until the ATTACH has stopped the process 177 // by signal SIGSTOP 178 static attach_state_t ptrace_waitpid(pid_t pid) { 179 int ret; 180 int status; 181 errno = 0; 182 while (true) { 183 // Wait for debuggee to stop. 184 ret = waitpid(pid, &status, 0); 185 if (ret == -1 && errno == ECHILD) { 186 // try cloned process. 187 ret = waitpid(pid, &status, __WALL); 188 } 189 if (ret >= 0) { 190 if (WIFSTOPPED(status)) { 191 // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP 192 // will still be pending and delivered when the process is DETACHED and the process 193 // will go to sleep. 194 if (WSTOPSIG(status) == SIGSTOP) { 195 // Debuggee stopped by SIGSTOP. 196 return ATTACH_SUCCESS; 197 } 198 if (!ptrace_continue(pid, WSTOPSIG(status))) { 199 print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status)); 200 return ATTACH_FAIL; 201 } 202 } else { 203 print_debug("waitpid(): Child process %d exited/terminated (status = 0x%x)\n", pid, status); 204 return ATTACH_THREAD_DEAD; 205 } 206 } else { 207 switch (errno) { 208 case EINTR: 209 continue; 210 break; 211 case ECHILD: 212 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid); 213 return ATTACH_THREAD_DEAD; 214 case EINVAL: 215 print_error("waitpid() failed. Invalid options argument.\n"); 216 return ATTACH_FAIL; 217 default: 218 print_error("waitpid() failed. Unexpected error %d\n", errno); 219 return ATTACH_FAIL; 220 } 221 } // else 222 } // while 223 } 224 225 // checks the state of the thread/process specified by "pid", by reading 226 // in the 'State:' value from the /proc/<pid>/status file. From the proc 227 // man page, "Current state of the process. One of "R (running)", 228 // "S (sleeping)", "D (disk sleep)", "T (stopped)", "T (tracing stop)", 229 // "Z (zombie)", or "X (dead)"." Assumes that the thread is dead if we 230 // don't find the status file or if the status is 'X' or 'Z'. 231 static bool process_doesnt_exist(pid_t pid) { 232 char fname[32]; 233 char buf[30]; 234 FILE *fp = NULL; 235 const char state_string[] = "State:"; 236 237 sprintf(fname, "/proc/%d/status", pid); 238 fp = fopen(fname, "r"); 239 if (fp == NULL) { 240 print_debug("can't open /proc/%d/status file\n", pid); 241 // Assume the thread does not exist anymore. 242 return true; 243 } 244 bool found_state = false; 245 size_t state_len = strlen(state_string); 246 while (fgets(buf, sizeof(buf), fp) != NULL) { 247 char *state = NULL; 248 if (strncmp (buf, state_string, state_len) == 0) { 249 found_state = true; 250 state = buf + state_len; 251 // Skip the spaces 252 while (isspace(*state)) { 253 state++; 254 } 255 // A state value of 'X' indicates that the thread is dead. 'Z' 256 // indicates that the thread is a zombie. 257 if (*state == 'X' || *state == 'Z') { 258 fclose (fp); 259 return true; 260 } 261 break; 262 } 263 } 264 // If the state value is not 'X' or 'Z', the thread exists. 265 if (!found_state) { 266 // We haven't found the line beginning with 'State:'. 267 // Assuming the thread exists. 268 print_error("Could not find the 'State:' string in the /proc/%d/status file\n", pid); 269 } 270 fclose (fp); 271 return false; 272 } 273 274 // attach to a process/thread specified by "pid" 275 static attach_state_t ptrace_attach(pid_t pid, char* err_buf, size_t err_buf_len) { 276 errno = 0; 277 if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) < 0) { 278 if (errno == EPERM || errno == ESRCH) { 279 // Check if the process/thread is exiting or is a zombie 280 if (process_doesnt_exist(pid)) { 281 print_debug("Thread with pid %d does not exist\n", pid); 282 return ATTACH_THREAD_DEAD; 283 } 284 } 285 char buf[200]; 286 char* msg = strerror_r(errno, buf, sizeof(buf)); 287 snprintf(err_buf, err_buf_len, "ptrace(PTRACE_ATTACH, ..) failed for %d: %s", pid, msg); 288 print_error("%s\n", err_buf); 289 return ATTACH_FAIL; 290 } else { 291 attach_state_t wait_ret = ptrace_waitpid(pid); 292 if (wait_ret == ATTACH_THREAD_DEAD) { 293 print_debug("Thread with pid %d does not exist\n", pid); 294 } 295 return wait_ret; 296 } 297 } 298 299 // ------------------------------------------------------- 300 // functions for obtaining library information 301 // ------------------------------------------------------- 302 303 /* 304 * splits a string _str_ into substrings with delimiter _delim_ by replacing old * delimiters with _new_delim_ (ideally, '\0'). the address of each substring 305 * is stored in array _ptrs_ as the return value. the maximum capacity of _ptrs_ * array is specified by parameter _n_. 306 * RETURN VALUE: total number of substrings (always <= _n_) 307 * NOTE: string _str_ is modified if _delim_!=_new_delim_ 308 */ 309 static int split_n_str(char * str, int n, char ** ptrs, char delim, char new_delim) 310 { 311 int i; 312 for(i = 0; i < n; i++) ptrs[i] = NULL; 313 if (str == NULL || n < 1 ) return 0; 314 315 i = 0; 316 317 // skipping leading blanks 318 while(*str&&*str==delim) str++; 319 320 while(*str&&i<n){ 321 ptrs[i++] = str; 322 while(*str&&*str!=delim) str++; 323 while(*str&&*str==delim) *(str++) = new_delim; 324 } 325 326 return i; 327 } 328 329 /* 330 * fgets without storing '\n' at the end of the string 331 */ 332 static char * fgets_no_cr(char * buf, int n, FILE *fp) 333 { 334 char * rslt = fgets(buf, n, fp); 335 if (rslt && buf && *buf){ 336 char *p = strchr(buf, '\0'); 337 if (*--p=='\n') *p='\0'; 338 } 339 return rslt; 340 } 341 342 // callback for read_thread_info 343 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) { 344 return add_thread_info(ph, pthread_id, lwp_id) != NULL; 345 } 346 347 static bool read_lib_info(struct ps_prochandle* ph) { 348 char fname[32]; 349 char buf[PATH_MAX]; 350 FILE *fp = NULL; 351 352 sprintf(fname, "/proc/%d/maps", ph->pid); 353 fp = fopen(fname, "r"); 354 if (fp == NULL) { 355 print_debug("can't open /proc/%d/maps file\n", ph->pid); 356 return false; 357 } 358 359 while(fgets_no_cr(buf, PATH_MAX, fp)){ 360 char * word[7]; 361 int nwords = split_n_str(buf, 7, word, ' ', '\0'); 362 363 if (nwords < 6) { 364 // not a shared library entry. ignore. 365 continue; 366 } 367 368 // SA does not handle the lines with patterns: 369 // "[stack]", "[heap]", "[vdso]", "[vsyscall]", etc. 370 if (word[5][0] == '[') { 371 // not a shared library entry. ignore. 372 continue; 373 } 374 375 if (nwords > 6) { 376 // prelink altered mapfile when the program is running. 377 // Entries like one below have to be skipped 378 // /lib64/libc-2.15.so (deleted) 379 // SO name in entries like one below have to be stripped. 380 // /lib64/libpthread-2.15.so.#prelink#.EECVts 381 char *s = strstr(word[5],".#prelink#"); 382 if (s == NULL) { 383 // No prelink keyword. skip deleted library 384 print_debug("skip shared object %s deleted by prelink\n", word[5]); 385 continue; 386 } 387 388 // Fall through 389 print_debug("rectifying shared object name %s changed by prelink\n", word[5]); 390 *s = 0; 391 } 392 393 if (find_lib(ph, word[5]) == false) { 394 intptr_t base; 395 lib_info* lib; 396 #ifdef _LP64 397 sscanf(word[0], "%lx", &base); 398 #else 399 sscanf(word[0], "%x", &base); 400 #endif 401 if ((lib = add_lib_info(ph, word[5], (uintptr_t)base)) == NULL) 402 continue; // ignore, add_lib_info prints error 403 404 // we don't need to keep the library open, symtab is already 405 // built. Only for core dump we need to keep the fd open. 406 close(lib->fd); 407 lib->fd = -1; 408 } 409 } 410 fclose(fp); 411 return true; 412 } 413 414 // detach a given pid 415 static bool ptrace_detach(pid_t pid) { 416 if (pid && ptrace(PTRACE_DETACH, pid, NULL, NULL) < 0) { 417 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid); 418 return false; 419 } else { 420 return true; 421 } 422 } 423 424 // detach all pids of a ps_prochandle 425 static void detach_all_pids(struct ps_prochandle* ph) { 426 thread_info* thr = ph->threads; 427 while (thr) { 428 ptrace_detach(thr->lwp_id); 429 thr = thr->next; 430 } 431 } 432 433 static void process_cleanup(struct ps_prochandle* ph) { 434 detach_all_pids(ph); 435 } 436 437 static ps_prochandle_ops process_ops = { 438 .release= process_cleanup, 439 .p_pread= process_read_data, 440 .p_pwrite= process_write_data, 441 .get_lwp_regs= process_get_lwp_regs 442 }; 443 444 // attach to the process. One and only one exposed stuff 445 JNIEXPORT struct ps_prochandle* JNICALL 446 Pgrab(pid_t pid, char* err_buf, size_t err_buf_len, bool is_in_container) { 447 struct ps_prochandle* ph = NULL; 448 thread_info* thr = NULL; 449 attach_state_t attach_status = ATTACH_SUCCESS; 450 451 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) { 452 snprintf(err_buf, err_buf_len, "can't allocate memory for ps_prochandle"); 453 print_debug("%s\n", err_buf); 454 return NULL; 455 } 456 457 if ((attach_status = ptrace_attach(pid, err_buf, err_buf_len)) != ATTACH_SUCCESS) { 458 if (attach_status == ATTACH_THREAD_DEAD) { 459 print_error("The process with pid %d does not exist.\n", pid); 460 } 461 free(ph); 462 return NULL; 463 } 464 465 // initialize ps_prochandle 466 ph->pid = pid; 467 468 // initialize vtable 469 ph->ops = &process_ops; 470 471 // read library info and symbol tables, must do this before attaching threads, 472 // as the symbols in the pthread library will be used to figure out 473 // the list of threads within the same process. 474 read_lib_info(ph); 475 476 // read thread info 477 if (is_in_container) { 478 /* 479 * If the process is running in the container, SA scans all tasks in 480 * /proc/<PID>/task to read all threads info. 481 */ 482 char taskpath[PATH_MAX]; 483 DIR *dirp; 484 struct dirent *entry; 485 486 snprintf(taskpath, PATH_MAX, "/proc/%d/task", ph->pid); 487 dirp = opendir(taskpath); 488 int lwp_id; 489 while ((entry = readdir(dirp)) != NULL) { 490 if (*entry->d_name == '.') { 491 continue; 492 } 493 lwp_id = atoi(entry->d_name); 494 if (lwp_id == ph->pid) { 495 continue; 496 } 497 add_new_thread(ph, -1, lwp_id); 498 } 499 closedir(dirp); 500 } else { 501 read_thread_info(ph, add_new_thread); 502 } 503 504 // attach to the threads 505 thr = ph->threads; 506 507 while (thr) { 508 thread_info* current_thr = thr; 509 thr = thr->next; 510 // don't attach to the main thread again 511 if (ph->pid != current_thr->lwp_id) { 512 if ((attach_status = ptrace_attach(current_thr->lwp_id, err_buf, err_buf_len)) != ATTACH_SUCCESS) { 513 if (attach_status == ATTACH_THREAD_DEAD) { 514 // Remove this thread from the threads list 515 delete_thread_info(ph, current_thr); 516 } 517 else { 518 Prelease(ph); 519 return NULL; 520 } // ATTACH_THREAD_DEAD 521 } // !ATTACH_SUCCESS 522 } 523 } 524 return ph; 525 }