1 /* 2 * Copyright (c) 2006, 2015, 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 <door.h> 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <limits.h> 29 #include <poll.h> 30 #include <signal.h> 31 #include <stdarg.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <string.h> 35 #include <sys/types.h> 36 #include <sys/stat.h> 37 #include <thread.h> 38 #include <unistd.h> 39 #include "jvm_dtrace.h" 40 41 // NOTE: These constants are used in JVM code as well. 42 // KEEP JVM CODE IN SYNC if you are going to change these... 43 44 #define DTRACE_ALLOC_PROBES 0x1 45 #define DTRACE_METHOD_PROBES 0x2 46 #define DTRACE_MONITOR_PROBES 0x4 47 #define DTRACE_ALL_PROBES -1 48 49 // generic error messages 50 #define JVM_ERR_OUT_OF_MEMORY "out of memory (native heap)" 51 #define JVM_ERR_INVALID_PARAM "invalid input parameter(s)" 52 #define JVM_ERR_NULL_PARAM "input paramater is NULL" 53 54 // error messages for attach 55 #define JVM_ERR_CANT_OPEN_DOOR "cannot open door file" 56 #define JVM_ERR_CANT_CREATE_ATTACH_FILE "cannot create attach file" 57 #define JVM_ERR_DOOR_FILE_PERMISSION "door file is not secure" 58 #define JVM_ERR_CANT_SIGNAL "cannot send SIGQUIT to target" 59 60 // error messages for enable probe 61 #define JVM_ERR_DOOR_CMD_SEND "door command send failed" 62 #define JVM_ERR_DOOR_CANT_READ_STATUS "cannot read door command status" 63 #define JVM_ERR_DOOR_CMD_STATUS "door command error status" 64 65 // error message for detach 66 #define JVM_ERR_CANT_CLOSE_DOOR "cannot close door file" 67 68 #define RESTARTABLE(_cmd, _result) do { \ 69 do { \ 70 _result = _cmd; \ 71 } while((_result == -1) && (errno == EINTR)); \ 72 } while(0) 73 74 struct _jvm_t { 75 pid_t pid; 76 int door_fd; 77 }; 78 79 static int libjvm_dtrace_debug; 80 static void print_debug(const char* fmt,...) { 81 if (libjvm_dtrace_debug) { 82 va_list alist; 83 va_start(alist, fmt); 84 fputs("libjvm_dtrace DEBUG: ", stderr); 85 vfprintf(stderr, fmt, alist); 86 va_end(alist); 87 } 88 } 89 90 /* Key for thread local error message */ 91 static thread_key_t jvm_error_key; 92 93 /* init function for this library */ 94 static void init_jvm_dtrace() { 95 /* check for env. var for debug mode */ 96 libjvm_dtrace_debug = getenv("LIBJVM_DTRACE_DEBUG") != NULL; 97 /* create key for thread local error message */ 98 if (thr_keycreate(&jvm_error_key, NULL) != 0) { 99 print_debug("can't create thread_key_t for jvm error key\n"); 100 // exit(1); ? 101 } 102 } 103 104 #pragma init(init_jvm_dtrace) 105 106 /* set thread local error message */ 107 static void set_jvm_error(const char* msg) { 108 thr_setspecific(jvm_error_key, (void*)msg); 109 } 110 111 /* clear thread local error message */ 112 static void clear_jvm_error() { 113 thr_setspecific(jvm_error_key, NULL); 114 } 115 116 /* file handling functions that can handle interrupt */ 117 118 static int file_open(const char* path, int flag) { 119 int ret; 120 RESTARTABLE(open(path, flag), ret); 121 return ret; 122 } 123 124 static int file_close(int fd) { 125 return close(fd); 126 } 127 128 static int file_read(int fd, char* buf, int len) { 129 int ret; 130 RESTARTABLE(read(fd, buf, len), ret); 131 return ret; 132 } 133 134 /* send SIGQUIT signal to given process */ 135 static int send_sigquit(pid_t pid) { 136 int ret; 137 RESTARTABLE(kill(pid, SIGQUIT), ret); 138 return ret; 139 } 140 141 /* called to check permissions on attach file */ 142 static int check_permission(const char* path) { 143 struct stat64 sb; 144 uid_t uid, gid; 145 int res; 146 147 /* 148 * Check that the path is owned by the effective uid/gid of this 149 * process. Also check that group/other access is not allowed. 150 */ 151 uid = geteuid(); 152 gid = getegid(); 153 154 res = stat64(path, &sb); 155 if (res != 0) { 156 print_debug("stat failed for %s\n", path); 157 return -1; 158 } 159 160 if ((sb.st_uid != uid) || (sb.st_gid != gid) || 161 ((sb.st_mode & (S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)) != 0)) { 162 print_debug("well-known file %s is not secure\n", path); 163 return -1; 164 } 165 return 0; 166 } 167 168 #define ATTACH_FILE_PATTERN "/tmp/.attach_pid%d" 169 170 /* fill-in the name of attach file name in given buffer */ 171 static void fill_attach_file_name(char* path, int len, pid_t pid) { 172 memset(path, 0, len); 173 sprintf(path, ATTACH_FILE_PATTERN, pid); 174 } 175 176 #define DOOR_FILE_PATTERN "/tmp/.java_pid%d" 177 178 /* open door file for the given JVM */ 179 static int open_door(pid_t pid) { 180 char path[PATH_MAX + 1]; 181 int fd; 182 183 sprintf(path, DOOR_FILE_PATTERN, pid); 184 fd = file_open(path, O_RDONLY); 185 if (fd < 0) { 186 set_jvm_error(JVM_ERR_CANT_OPEN_DOOR); 187 print_debug("cannot open door file %s\n", path); 188 return -1; 189 } 190 print_debug("opened door file %s\n", path); 191 if (check_permission(path) != 0) { 192 set_jvm_error(JVM_ERR_DOOR_FILE_PERMISSION); 193 print_debug("check permission failed for %s\n", path); 194 file_close(fd); 195 fd = -1; 196 } 197 return fd; 198 } 199 200 /* create attach file for given process */ 201 static int create_attach_file(pid_t pid) { 202 char path[PATH_MAX + 1]; 203 int fd; 204 fill_attach_file_name(path, sizeof(path), pid); 205 fd = file_open(path, O_CREAT | O_RDWR); 206 if (fd < 0) { 207 set_jvm_error(JVM_ERR_CANT_CREATE_ATTACH_FILE); 208 print_debug("cannot create file %s\n", path); 209 } else { 210 print_debug("created attach file %s\n", path); 211 } 212 return fd; 213 } 214 215 /* delete attach file for given process */ 216 static void delete_attach_file(pid_t pid) { 217 char path[PATH_MAX + 1]; 218 fill_attach_file_name(path, sizeof(path), pid); 219 int res = unlink(path); 220 if (res) { 221 print_debug("cannot delete attach file %s\n", path); 222 } else { 223 print_debug("deleted attach file %s\n", path); 224 } 225 } 226 227 /* attach to given JVM */ 228 jvm_t* jvm_attach(pid_t pid) { 229 jvm_t* jvm; 230 int door_fd, attach_fd, i = 0; 231 232 jvm = (jvm_t*) calloc(1, sizeof(jvm_t)); 233 if (jvm == NULL) { 234 set_jvm_error(JVM_ERR_OUT_OF_MEMORY); 235 print_debug("calloc failed in %s at %d\n", __FILE__, __LINE__); 236 return NULL; 237 } 238 jvm->pid = pid; 239 attach_fd = -1; 240 241 door_fd = open_door(pid); 242 if (door_fd < 0) { 243 print_debug("trying to create attach file\n"); 244 if ((attach_fd = create_attach_file(pid)) < 0) { 245 goto quit; 246 } 247 248 /* send QUIT signal to the target so that it will 249 * check for the attach file. 250 */ 251 if (send_sigquit(pid) != 0) { 252 set_jvm_error(JVM_ERR_CANT_SIGNAL); 253 print_debug("sending SIGQUIT failed\n"); 254 goto quit; 255 } 256 257 /* give the target VM time to start the attach mechanism */ 258 do { 259 int res; 260 RESTARTABLE(poll(0, 0, 200), res); 261 door_fd = open_door(pid); 262 i++; 263 } while (i <= 50 && door_fd == -1); 264 if (door_fd < 0) { 265 print_debug("Unable to open door to process %d\n", pid); 266 goto quit; 267 } 268 } 269 270 quit: 271 if (attach_fd >= 0) { 272 file_close(attach_fd); 273 delete_attach_file(jvm->pid); 274 } 275 if (door_fd >= 0) { 276 jvm->door_fd = door_fd; 277 clear_jvm_error(); 278 } else { 279 free(jvm); 280 jvm = NULL; 281 } 282 return jvm; 283 } 284 285 /* return the last thread local error message */ 286 const char* jvm_get_last_error() { 287 const char* res = NULL; 288 thr_getspecific(jvm_error_key, (void**)&res); 289 return res; 290 } 291 292 /* detach the givenb JVM */ 293 int jvm_detach(jvm_t* jvm) { 294 if (jvm) { 295 int res = 0; 296 if (jvm->door_fd != -1) { 297 if (file_close(jvm->door_fd) != 0) { 298 set_jvm_error(JVM_ERR_CANT_CLOSE_DOOR); 299 res = -1; 300 } else { 301 clear_jvm_error(); 302 } 303 } 304 free(jvm); 305 return res; 306 } else { 307 set_jvm_error(JVM_ERR_NULL_PARAM); 308 print_debug("jvm_t* is NULL\n"); 309 return -1; 310 } 311 } 312 313 /* 314 * A simple table to translate some known errors into reasonable 315 * error messages 316 */ 317 static struct { 318 int err; 319 const char* msg; 320 } const error_messages[] = { 321 { 100, "Bad request" }, 322 { 101, "Protocol mismatch" }, 323 { 102, "Resource failure" }, 324 { 103, "Internal error" }, 325 { 104, "Permission denied" }, 326 }; 327 328 /* 329 * Lookup the given error code and return the appropriate 330 * message. If not found return NULL. 331 */ 332 static const char* translate_error(int err) { 333 int table_size = sizeof(error_messages) / sizeof(error_messages[0]); 334 int i; 335 336 for (i=0; i<table_size; i++) { 337 if (err == error_messages[i].err) { 338 return error_messages[i].msg; 339 } 340 } 341 return NULL; 342 } 343 344 /* 345 * Current protocol version 346 */ 347 static const char* PROTOCOL_VERSION = "1"; 348 349 #define RES_BUF_SIZE 128 350 351 /* 352 * Enqueue attach-on-demand command to the given JVM 353 */ 354 static 355 int enqueue_command(jvm_t* jvm, const char* cstr, int arg_count, const char** args) { 356 size_t size; 357 door_arg_t door_args; 358 char res_buffer[RES_BUF_SIZE]; 359 int rc, i; 360 char* buf = NULL; 361 int result = -1; 362 363 /* 364 * First we get the command string and create the start of the 365 * argument string to send to the target VM: 366 * <ver>\0<cmd>\0 367 */ 368 if (cstr == NULL) { 369 print_debug("command name is NULL\n"); 370 goto quit; 371 } 372 size = strlen(PROTOCOL_VERSION) + strlen(cstr) + 2; 373 buf = (char*)malloc(size); 374 if (buf != NULL) { 375 char* pos = buf; 376 strcpy(buf, PROTOCOL_VERSION); 377 pos += strlen(PROTOCOL_VERSION)+1; 378 strcpy(pos, cstr); 379 } else { 380 set_jvm_error(JVM_ERR_OUT_OF_MEMORY); 381 print_debug("malloc failed at %d in %s\n", __LINE__, __FILE__); 382 goto quit; 383 } 384 385 /* 386 * Next we iterate over the arguments and extend the buffer 387 * to include them. 388 */ 389 for (i=0; i<arg_count; i++) { 390 cstr = args[i]; 391 if (cstr != NULL) { 392 size_t len = strlen(cstr); 393 char* newbuf = (char*)realloc(buf, size+len+1); 394 if (newbuf == NULL) { 395 set_jvm_error(JVM_ERR_OUT_OF_MEMORY); 396 print_debug("realloc failed in %s at %d\n", __FILE__, __LINE__); 397 goto quit; 398 } 399 buf = newbuf; 400 strcpy(buf+size, cstr); 401 size += len+1; 402 } 403 } 404 405 /* 406 * The arguments to the door function are in 'buf' so we now 407 * do the door call 408 */ 409 door_args.data_ptr = buf; 410 door_args.data_size = size; 411 door_args.desc_ptr = NULL; 412 door_args.desc_num = 0; 413 door_args.rbuf = (char*)&res_buffer; 414 door_args.rsize = sizeof(res_buffer); 415 416 RESTARTABLE(door_call(jvm->door_fd, &door_args), rc); 417 418 /* 419 * door_call failed 420 */ 421 if (rc == -1) { 422 print_debug("door_call failed\n"); 423 } else { 424 /* 425 * door_call succeeded but the call didn't return the expected jint. 426 */ 427 if (door_args.data_size < sizeof(int)) { 428 print_debug("Enqueue error - reason unknown as result is truncated!"); 429 } else { 430 int* res = (int*)(door_args.data_ptr); 431 if (*res != 0) { 432 const char* msg = translate_error(*res); 433 if (msg == NULL) { 434 print_debug("Unable to enqueue command to target VM: %d\n", *res); 435 } else { 436 print_debug("Unable to enqueue command to target VM: %s\n", msg); 437 } 438 } else { 439 /* 440 * The door call should return a file descriptor to one end of 441 * a socket pair 442 */ 443 if ((door_args.desc_ptr != NULL) && 444 (door_args.desc_num == 1) && 445 (door_args.desc_ptr->d_attributes & DOOR_DESCRIPTOR)) { 446 result = door_args.desc_ptr->d_data.d_desc.d_descriptor; 447 } else { 448 print_debug("Reply from enqueue missing descriptor!\n"); 449 } 450 } 451 } 452 } 453 454 quit: 455 if (buf) free(buf); 456 return result; 457 } 458 459 /* read status code for a door command */ 460 static int read_status(int fd) { 461 char ch, buf[16]; 462 int index = 0; 463 464 while (1) { 465 if (file_read(fd, &ch, sizeof(ch)) != sizeof(ch)) { 466 set_jvm_error(JVM_ERR_DOOR_CANT_READ_STATUS); 467 print_debug("door cmd status: read status failed\n"); 468 return -1; 469 } 470 buf[index++] = ch; 471 if (ch == '\n') { 472 buf[index - 1] = '\0'; 473 return atoi(buf); 474 } 475 if (index == sizeof(buf)) { 476 set_jvm_error(JVM_ERR_DOOR_CANT_READ_STATUS); 477 print_debug("door cmd status: read status overflow\n"); 478 return -1; 479 } 480 } 481 } 482 483 static const char* ENABLE_DPROBES_CMD = "enabledprobes"; 484 485 /* enable one or more DTrace probes for a given JVM */ 486 int jvm_enable_dtprobes(jvm_t* jvm, int num_probe_types, const char** probe_types) { 487 int fd, status = 0; 488 char ch; 489 const char* args[1]; 490 char buf[16]; 491 int probe_type = 0, index; 492 int count = 0; 493 494 if (jvm == NULL) { 495 set_jvm_error(JVM_ERR_NULL_PARAM); 496 print_debug("jvm_t* is NULL\n"); 497 return -1; 498 } 499 500 if (num_probe_types == 0 || probe_types == NULL || 501 probe_types[0] == NULL) { 502 set_jvm_error(JVM_ERR_INVALID_PARAM); 503 print_debug("invalid probe type argument(s)\n"); 504 return -1; 505 } 506 507 for (index = 0; index < num_probe_types; index++) { 508 const char* p = probe_types[index]; 509 if (strcmp(p, JVM_DTPROBE_OBJECT_ALLOC) == 0) { 510 probe_type |= DTRACE_ALLOC_PROBES; 511 count++; 512 } else if (strcmp(p, JVM_DTPROBE_METHOD_ENTRY) == 0 || 513 strcmp(p, JVM_DTPROBE_METHOD_RETURN) == 0) { 514 probe_type |= DTRACE_METHOD_PROBES; 515 count++; 516 } else if (strcmp(p, JVM_DTPROBE_MONITOR_ENTER) == 0 || 517 strcmp(p, JVM_DTPROBE_MONITOR_ENTERED) == 0 || 518 strcmp(p, JVM_DTPROBE_MONITOR_EXIT) == 0 || 519 strcmp(p, JVM_DTPROBE_MONITOR_WAIT) == 0 || 520 strcmp(p, JVM_DTPROBE_MONITOR_WAITED) == 0 || 521 strcmp(p, JVM_DTPROBE_MONITOR_NOTIFY) == 0 || 522 strcmp(p, JVM_DTPROBE_MONITOR_NOTIFYALL) == 0) { 523 probe_type |= DTRACE_MONITOR_PROBES; 524 count++; 525 } else if (strcmp(p, JVM_DTPROBE_ALL) == 0) { 526 probe_type |= DTRACE_ALL_PROBES; 527 count++; 528 } 529 } 530 531 if (count == 0) { 532 return count; 533 } 534 sprintf(buf, "%d", probe_type); 535 args[0] = buf; 536 537 fd = enqueue_command(jvm, ENABLE_DPROBES_CMD, 1, args); 538 if (fd < 0) { 539 set_jvm_error(JVM_ERR_DOOR_CMD_SEND); 540 return -1; 541 } 542 543 status = read_status(fd); 544 // non-zero status is error 545 if (status) { 546 set_jvm_error(JVM_ERR_DOOR_CMD_STATUS); 547 print_debug("%s command failed (status: %d) in target JVM\n", 548 ENABLE_DPROBES_CMD, status); 549 file_close(fd); 550 return -1; 551 } 552 // read from stream until EOF 553 while (file_read(fd, &ch, sizeof(ch)) == sizeof(ch)) { 554 if (libjvm_dtrace_debug) { 555 printf("%c", ch); 556 } 557 } 558 559 file_close(fd); 560 clear_jvm_error(); 561 return count; 562 }