1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/slab.h> 3 #include <linux/file.h> 4 #include <linux/fdtable.h> 5 #include <linux/freezer.h> 6 #include <linux/mm.h> 7 #include <linux/stat.h> 8 #include <linux/fcntl.h> 9 #include <linux/swap.h> 10 #include <linux/ctype.h> 11 #include <linux/string.h> 12 #include <linux/init.h> 13 #include <linux/pagemap.h> 14 #include <linux/perf_event.h> 15 #include <linux/highmem.h> 16 #include <linux/spinlock.h> 17 #include <linux/key.h> 18 #include <linux/personality.h> 19 #include <linux/binfmts.h> 20 #include <linux/coredump.h> 21 #include <linux/sched/coredump.h> 22 #include <linux/sched/signal.h> 23 #include <linux/sched/task_stack.h> 24 #include <linux/utsname.h> 25 #include <linux/pid_namespace.h> 26 #include <linux/module.h> 27 #include <linux/namei.h> 28 #include <linux/mount.h> 29 #include <linux/security.h> 30 #include <linux/syscalls.h> 31 #include <linux/tsacct_kern.h> 32 #include <linux/cn_proc.h> 33 #include <linux/audit.h> 34 #include <linux/tracehook.h> 35 #include <linux/kmod.h> 36 #include <linux/fsnotify.h> 37 #include <linux/fs_struct.h> 38 #include <linux/pipe_fs_i.h> 39 #include <linux/oom.h> 40 #include <linux/compat.h> 41 #include <linux/fs.h> 42 #include <linux/path.h> 43 #include <linux/timekeeping.h> 44 45 #include <linux/uaccess.h> 46 #include <asm/mmu_context.h> 47 #include <asm/tlb.h> 48 #include <asm/exec.h> 49 50 #include <trace/events/task.h> 51 #include "internal.h" 52 53 #include <trace/events/sched.h> 54 55 int core_uses_pid; 56 unsigned int core_pipe_limit; 57 char core_pattern[CORENAME_MAX_SIZE] = "core"; 58 static int core_name_size = CORENAME_MAX_SIZE; 59 60 struct core_name { 61 char *corename; 62 int used, size; 63 }; 64 65 /* The maximal length of core_pattern is also specified in sysctl.c */ 66 67 static int expand_corename(struct core_name *cn, int size) 68 { 69 char *corename = krealloc(cn->corename, size, GFP_KERNEL); 70 71 if (!corename) 72 return -ENOMEM; 73 74 if (size > core_name_size) /* racy but harmless */ 75 core_name_size = size; 76 77 cn->size = ksize(corename); 78 cn->corename = corename; 79 return 0; 80 } 81 82 static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt, 83 va_list arg) 84 { 85 int free, need; 86 va_list arg_copy; 87 88 again: 89 free = cn->size - cn->used; 90 91 va_copy(arg_copy, arg); 92 need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy); 93 va_end(arg_copy); 94 95 if (need < free) { 96 cn->used += need; 97 return 0; 98 } 99 100 if (!expand_corename(cn, cn->size + need - free + 1)) 101 goto again; 102 103 return -ENOMEM; 104 } 105 106 static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...) 107 { 108 va_list arg; 109 int ret; 110 111 va_start(arg, fmt); 112 ret = cn_vprintf(cn, fmt, arg); 113 va_end(arg); 114 115 return ret; 116 } 117 118 static __printf(2, 3) 119 int cn_esc_printf(struct core_name *cn, const char *fmt, ...) 120 { 121 int cur = cn->used; 122 va_list arg; 123 int ret; 124 125 va_start(arg, fmt); 126 ret = cn_vprintf(cn, fmt, arg); 127 va_end(arg); 128 129 if (ret == 0) { 130 /* 131 * Ensure that this coredump name component can't cause the 132 * resulting corefile path to consist of a ".." or ".". 133 */ 134 if ((cn->used - cur == 1 && cn->corename[cur] == '.') || 135 (cn->used - cur == 2 && cn->corename[cur] == '.' 136 && cn->corename[cur+1] == '.')) 137 cn->corename[cur] = '!'; 138 139 /* 140 * Empty names are fishy and could be used to create a "//" in a 141 * corefile name, causing the coredump to happen one directory 142 * level too high. Enforce that all components of the core 143 * pattern are at least one character long. 144 */ 145 if (cn->used == cur) 146 ret = cn_printf(cn, "!"); 147 } 148 149 for (; cur < cn->used; ++cur) { 150 if (cn->corename[cur] == '/') 151 cn->corename[cur] = '!'; 152 } 153 return ret; 154 } 155 156 static int cn_print_exe_file(struct core_name *cn) 157 { 158 struct file *exe_file; 159 char *pathbuf, *path; 160 int ret; 161 162 exe_file = get_mm_exe_file(current->mm); 163 if (!exe_file) 164 return cn_esc_printf(cn, "%s (path unknown)", current->comm); 165 166 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); 167 if (!pathbuf) { 168 ret = -ENOMEM; 169 goto put_exe_file; 170 } 171 172 path = file_path(exe_file, pathbuf, PATH_MAX); 173 if (IS_ERR(path)) { 174 ret = PTR_ERR(path); 175 goto free_buf; 176 } 177 178 ret = cn_esc_printf(cn, "%s", path); 179 180 free_buf: 181 kfree(pathbuf); 182 put_exe_file: 183 fput(exe_file); 184 return ret; 185 } 186 187 /* format_corename will inspect the pattern parameter, and output a 188 * name into corename, which must have space for at least 189 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 190 */ 191 static int format_corename(struct core_name *cn, struct coredump_params *cprm, 192 size_t **argv, int *argc) 193 { 194 const struct cred *cred = current_cred(); 195 const char *pat_ptr = core_pattern; 196 int ispipe = (*pat_ptr == '|'); 197 bool was_space = false; 198 int pid_in_pattern = 0; 199 int err = 0; 200 201 cn->used = 0; 202 cn->corename = NULL; 203 if (expand_corename(cn, core_name_size)) 204 return -ENOMEM; 205 cn->corename[0] = '\0'; 206 207 if (ispipe) { 208 int argvs = sizeof(core_pattern) / 2; 209 (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); 210 if (!(*argv)) 211 return -ENOMEM; 212 (*argv)[(*argc)++] = 0; 213 ++pat_ptr; 214 } 215 216 /* Repeat as long as we have more pattern to process and more output 217 space */ 218 while (*pat_ptr) { 219 /* 220 * Split on spaces before doing template expansion so that 221 * %e and %E don't get split if they have spaces in them 222 */ 223 if (ispipe) { 224 if (isspace(*pat_ptr)) { 225 was_space = true; 226 pat_ptr++; 227 continue; 228 } else if (was_space) { 229 was_space = false; 230 err = cn_printf(cn, "%c", '\0'); 231 if (err) 232 return err; 233 (*argv)[(*argc)++] = cn->used; 234 } 235 } 236 if (*pat_ptr != '%') { 237 err = cn_printf(cn, "%c", *pat_ptr++); 238 } else { 239 switch (*++pat_ptr) { 240 /* single % at the end, drop that */ 241 case 0: 242 goto out; 243 /* Double percent, output one percent */ 244 case '%': 245 err = cn_printf(cn, "%c", '%'); 246 break; 247 /* pid */ 248 case 'p': 249 pid_in_pattern = 1; 250 err = cn_printf(cn, "%d", 251 task_tgid_vnr(current)); 252 break; 253 /* global pid */ 254 case 'P': 255 err = cn_printf(cn, "%d", 256 task_tgid_nr(current)); 257 break; 258 case 'i': 259 err = cn_printf(cn, "%d", 260 task_pid_vnr(current)); 261 break; 262 case 'I': 263 err = cn_printf(cn, "%d", 264 task_pid_nr(current)); 265 break; 266 /* uid */ 267 case 'u': 268 err = cn_printf(cn, "%u", 269 from_kuid(&init_user_ns, 270 cred->uid)); 271 break; 272 /* gid */ 273 case 'g': 274 err = cn_printf(cn, "%u", 275 from_kgid(&init_user_ns, 276 cred->gid)); 277 break; 278 case 'd': 279 err = cn_printf(cn, "%d", 280 __get_dumpable(cprm->mm_flags)); 281 break; 282 /* signal that caused the coredump */ 283 case 's': 284 err = cn_printf(cn, "%d", 285 cprm->siginfo->si_signo); 286 break; 287 /* UNIX time of coredump */ 288 case 't': { 289 time64_t time; 290 291 time = ktime_get_real_seconds(); 292 err = cn_printf(cn, "%lld", time); 293 break; 294 } 295 /* hostname */ 296 case 'h': 297 down_read(&uts_sem); 298 err = cn_esc_printf(cn, "%s", 299 utsname()->nodename); 300 up_read(&uts_sem); 301 break; 302 /* executable */ 303 case 'e': 304 err = cn_esc_printf(cn, "%s", current->comm); 305 break; 306 case 'E': 307 err = cn_print_exe_file(cn); 308 break; 309 /* core limit size */ 310 case 'c': 311 err = cn_printf(cn, "%lu", 312 rlimit(RLIMIT_CORE)); 313 break; 314 default: 315 break; 316 } 317 ++pat_ptr; 318 } 319 320 if (err) 321 return err; 322 } 323 324 out: 325 /* Backward compatibility with core_uses_pid: 326 * 327 * If core_pattern does not include a %p (as is the default) 328 * and core_uses_pid is set, then .%pid will be appended to 329 * the filename. Do not do this for piped commands. */ 330 if (!ispipe && !pid_in_pattern && core_uses_pid) { 331 err = cn_printf(cn, ".%d", task_tgid_vnr(current)); 332 if (err) 333 return err; 334 } 335 return ispipe; 336 } 337 338 static int zap_process(struct task_struct *start, int exit_code, int flags) 339 { 340 struct task_struct *t; 341 int nr = 0; 342 343 /* ignore all signals except SIGKILL, see prepare_signal() */ 344 start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; 345 start->signal->group_exit_code = exit_code; 346 start->signal->group_stop_count = 0; 347 348 for_each_thread(start, t) { 349 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 350 if (t != current && t->mm) { 351 sigaddset(&t->pending.signal, SIGKILL); 352 signal_wake_up(t, 1); 353 nr++; 354 } 355 } 356 357 return nr; 358 } 359 360 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 361 struct core_state *core_state, int exit_code) 362 { 363 struct task_struct *g, *p; 364 unsigned long flags; 365 int nr = -EAGAIN; 366 367 spin_lock_irq(&tsk->sighand->siglock); 368 if (!signal_group_exit(tsk->signal)) { 369 mm->core_state = core_state; 370 tsk->signal->group_exit_task = tsk; 371 nr = zap_process(tsk, exit_code, 0); 372 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 373 } 374 spin_unlock_irq(&tsk->sighand->siglock); 375 if (unlikely(nr < 0)) 376 return nr; 377 378 tsk->flags |= PF_DUMPCORE; 379 if (atomic_read(&mm->mm_users) == nr + 1) 380 goto done; 381 /* 382 * We should find and kill all tasks which use this mm, and we should 383 * count them correctly into ->nr_threads. We don't take tasklist 384 * lock, but this is safe wrt: 385 * 386 * fork: 387 * None of sub-threads can fork after zap_process(leader). All 388 * processes which were created before this point should be 389 * visible to zap_threads() because copy_process() adds the new 390 * process to the tail of init_task.tasks list, and lock/unlock 391 * of ->siglock provides a memory barrier. 392 * 393 * do_exit: 394 * The caller holds mm->mmap_sem. This means that the task which 395 * uses this mm can't pass exit_mm(), so it can't exit or clear 396 * its ->mm. 397 * 398 * de_thread: 399 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 400 * we must see either old or new leader, this does not matter. 401 * However, it can change p->sighand, so lock_task_sighand(p) 402 * must be used. Since p->mm != NULL and we hold ->mmap_sem 403 * it can't fail. 404 * 405 * Note also that "g" can be the old leader with ->mm == NULL 406 * and already unhashed and thus removed from ->thread_group. 407 * This is OK, __unhash_process()->list_del_rcu() does not 408 * clear the ->next pointer, we will find the new leader via 409 * next_thread(). 410 */ 411 rcu_read_lock(); 412 for_each_process(g) { 413 if (g == tsk->group_leader) 414 continue; 415 if (g->flags & PF_KTHREAD) 416 continue; 417 418 for_each_thread(g, p) { 419 if (unlikely(!p->mm)) 420 continue; 421 if (unlikely(p->mm == mm)) { 422 lock_task_sighand(p, &flags); 423 nr += zap_process(p, exit_code, 424 SIGNAL_GROUP_EXIT); 425 unlock_task_sighand(p, &flags); 426 } 427 break; 428 } 429 } 430 rcu_read_unlock(); 431 done: 432 atomic_set(&core_state->nr_threads, nr); 433 return nr; 434 } 435 436 static int coredump_wait(int exit_code, struct core_state *core_state) 437 { 438 struct task_struct *tsk = current; 439 struct mm_struct *mm = tsk->mm; 440 int core_waiters = -EBUSY; 441 442 init_completion(&core_state->startup); 443 core_state->dumper.task = tsk; 444 core_state->dumper.next = NULL; 445 446 if (down_write_killable(&mm->mmap_sem)) 447 return -EINTR; 448 449 if (!mm->core_state) 450 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 451 up_write(&mm->mmap_sem); 452 453 if (core_waiters > 0) { 454 struct core_thread *ptr; 455 456 freezer_do_not_count(); 457 wait_for_completion(&core_state->startup); 458 freezer_count(); 459 /* 460 * Wait for all the threads to become inactive, so that 461 * all the thread context (extended register state, like 462 * fpu etc) gets copied to the memory. 463 */ 464 ptr = core_state->dumper.next; 465 while (ptr != NULL) { 466 wait_task_inactive(ptr->task, 0); 467 ptr = ptr->next; 468 } 469 } 470 471 return core_waiters; 472 } 473 474 static void coredump_finish(struct mm_struct *mm, bool core_dumped) 475 { 476 struct core_thread *curr, *next; 477 struct task_struct *task; 478 479 spin_lock_irq(¤t->sighand->siglock); 480 if (core_dumped && !__fatal_signal_pending(current)) 481 current->signal->group_exit_code |= 0x80; 482 current->signal->group_exit_task = NULL; 483 current->signal->flags = SIGNAL_GROUP_EXIT; 484 spin_unlock_irq(¤t->sighand->siglock); 485 486 next = mm->core_state->dumper.next; 487 while ((curr = next) != NULL) { 488 next = curr->next; 489 task = curr->task; 490 /* 491 * see exit_mm(), curr->task must not see 492 * ->task == NULL before we read ->next. 493 */ 494 smp_mb(); 495 curr->task = NULL; 496 wake_up_process(task); 497 } 498 499 mm->core_state = NULL; 500 } 501 502 static bool dump_interrupted(void) 503 { 504 /* 505 * SIGKILL or freezing() interrupt the coredumping. Perhaps we 506 * can do try_to_freeze() and check __fatal_signal_pending(), 507 * but then we need to teach dump_write() to restart and clear 508 * TIF_SIGPENDING. 509 */ 510 return signal_pending(current); 511 } 512 513 static void wait_for_dump_helpers(struct file *file) 514 { 515 struct pipe_inode_info *pipe = file->private_data; 516 517 pipe_lock(pipe); 518 pipe->readers++; 519 pipe->writers--; 520 wake_up_interruptible_sync(&pipe->rd_wait); 521 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 522 pipe_unlock(pipe); 523 524 /* 525 * We actually want wait_event_freezable() but then we need 526 * to clear TIF_SIGPENDING and improve dump_interrupted(). 527 */ 528 wait_event_interruptible(pipe->rd_wait, pipe->readers == 1); 529 530 pipe_lock(pipe); 531 pipe->readers--; 532 pipe->writers++; 533 pipe_unlock(pipe); 534 } 535 536 /* 537 * umh_pipe_setup 538 * helper function to customize the process used 539 * to collect the core in userspace. Specifically 540 * it sets up a pipe and installs it as fd 0 (stdin) 541 * for the process. Returns 0 on success, or 542 * PTR_ERR on failure. 543 * Note that it also sets the core limit to 1. This 544 * is a special value that we use to trap recursive 545 * core dumps 546 */ 547 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) 548 { 549 struct file *files[2]; 550 struct coredump_params *cp = (struct coredump_params *)info->data; 551 int err = create_pipe_files(files, 0); 552 if (err) 553 return err; 554 555 cp->file = files[1]; 556 557 err = replace_fd(0, files[0], 0); 558 fput(files[0]); 559 /* and disallow core files too */ 560 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; 561 562 return err; 563 } 564 565 void do_coredump(const kernel_siginfo_t *siginfo) 566 { 567 struct core_state core_state; 568 struct core_name cn; 569 struct mm_struct *mm = current->mm; 570 struct linux_binfmt * binfmt; 571 const struct cred *old_cred; 572 struct cred *cred; 573 int retval = 0; 574 int ispipe; 575 size_t *argv = NULL; 576 int argc = 0; 577 struct files_struct *displaced; 578 /* require nonrelative corefile path and be extra careful */ 579 bool need_suid_safe = false; 580 bool core_dumped = false; 581 static atomic_t core_dump_count = ATOMIC_INIT(0); 582 struct coredump_params cprm = { 583 .siginfo = siginfo, 584 .regs = signal_pt_regs(), 585 .limit = rlimit(RLIMIT_CORE), 586 /* 587 * We must use the same mm->flags while dumping core to avoid 588 * inconsistency of bit flags, since this flag is not protected 589 * by any locks. 590 */ 591 .mm_flags = mm->flags, 592 }; 593 594 audit_core_dumps(siginfo->si_signo); 595 596 binfmt = mm->binfmt; 597 if (!binfmt || !binfmt->core_dump) 598 goto fail; 599 if (!__get_dumpable(cprm.mm_flags)) 600 goto fail; 601 602 cred = prepare_creds(); 603 if (!cred) 604 goto fail; 605 /* 606 * We cannot trust fsuid as being the "true" uid of the process 607 * nor do we know its entire history. We only know it was tainted 608 * so we dump it as root in mode 2, and only into a controlled 609 * environment (pipe handler or fully qualified path). 610 */ 611 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { 612 /* Setuid core dump mode */ 613 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ 614 need_suid_safe = true; 615 } 616 617 retval = coredump_wait(siginfo->si_signo, &core_state); 618 if (retval < 0) 619 goto fail_creds; 620 621 old_cred = override_creds(cred); 622 623 ispipe = format_corename(&cn, &cprm, &argv, &argc); 624 625 if (ispipe) { 626 int argi; 627 int dump_count; 628 char **helper_argv; 629 struct subprocess_info *sub_info; 630 631 if (ispipe < 0) { 632 printk(KERN_WARNING "format_corename failed\n"); 633 printk(KERN_WARNING "Aborting core\n"); 634 goto fail_unlock; 635 } 636 637 if (cprm.limit == 1) { 638 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. 639 * 640 * Normally core limits are irrelevant to pipes, since 641 * we're not writing to the file system, but we use 642 * cprm.limit of 1 here as a special value, this is a 643 * consistent way to catch recursive crashes. 644 * We can still crash if the core_pattern binary sets 645 * RLIM_CORE = !1, but it runs as root, and can do 646 * lots of stupid things. 647 * 648 * Note that we use task_tgid_vnr here to grab the pid 649 * of the process group leader. That way we get the 650 * right pid if a thread in a multi-threaded 651 * core_pattern process dies. 652 */ 653 printk(KERN_WARNING 654 "Process %d(%s) has RLIMIT_CORE set to 1\n", 655 task_tgid_vnr(current), current->comm); 656 printk(KERN_WARNING "Aborting core\n"); 657 goto fail_unlock; 658 } 659 cprm.limit = RLIM_INFINITY; 660 661 dump_count = atomic_inc_return(&core_dump_count); 662 if (core_pipe_limit && (core_pipe_limit < dump_count)) { 663 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", 664 task_tgid_vnr(current), current->comm); 665 printk(KERN_WARNING "Skipping core dump\n"); 666 goto fail_dropcount; 667 } 668 669 helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), 670 GFP_KERNEL); 671 if (!helper_argv) { 672 printk(KERN_WARNING "%s failed to allocate memory\n", 673 __func__); 674 goto fail_dropcount; 675 } 676 for (argi = 0; argi < argc; argi++) 677 helper_argv[argi] = cn.corename + argv[argi]; 678 helper_argv[argi] = NULL; 679 680 retval = -ENOMEM; 681 sub_info = call_usermodehelper_setup(helper_argv[0], 682 helper_argv, NULL, GFP_KERNEL, 683 umh_pipe_setup, NULL, &cprm); 684 if (sub_info) 685 retval = call_usermodehelper_exec(sub_info, 686 UMH_WAIT_EXEC); 687 688 kfree(helper_argv); 689 if (retval) { 690 printk(KERN_INFO "Core dump to |%s pipe failed\n", 691 cn.corename); 692 goto close_fail; 693 } 694 } else { 695 struct inode *inode; 696 int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | 697 O_LARGEFILE | O_EXCL; 698 699 if (cprm.limit < binfmt->min_coredump) 700 goto fail_unlock; 701 702 if (need_suid_safe && cn.corename[0] != '/') { 703 printk(KERN_WARNING "Pid %d(%s) can only dump core "\ 704 "to fully qualified path!\n", 705 task_tgid_vnr(current), current->comm); 706 printk(KERN_WARNING "Skipping core dump\n"); 707 goto fail_unlock; 708 } 709 710 /* 711 * Unlink the file if it exists unless this is a SUID 712 * binary - in that case, we're running around with root 713 * privs and don't want to unlink another user's coredump. 714 */ 715 if (!need_suid_safe) { 716 /* 717 * If it doesn't exist, that's fine. If there's some 718 * other problem, we'll catch it at the filp_open(). 719 */ 720 do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); 721 } 722 723 /* 724 * There is a race between unlinking and creating the 725 * file, but if that causes an EEXIST here, that's 726 * fine - another process raced with us while creating 727 * the corefile, and the other process won. To userspace, 728 * what matters is that at least one of the two processes 729 * writes its coredump successfully, not which one. 730 */ 731 if (need_suid_safe) { 732 /* 733 * Using user namespaces, normal user tasks can change 734 * their current->fs->root to point to arbitrary 735 * directories. Since the intention of the "only dump 736 * with a fully qualified path" rule is to control where 737 * coredumps may be placed using root privileges, 738 * current->fs->root must not be used. Instead, use the 739 * root directory of init_task. 740 */ 741 struct path root; 742 743 task_lock(&init_task); 744 get_fs_root(init_task.fs, &root); 745 task_unlock(&init_task); 746 cprm.file = file_open_root(root.dentry, root.mnt, 747 cn.corename, open_flags, 0600); 748 path_put(&root); 749 } else { 750 cprm.file = filp_open(cn.corename, open_flags, 0600); 751 } 752 if (IS_ERR(cprm.file)) 753 goto fail_unlock; 754 755 inode = file_inode(cprm.file); 756 if (inode->i_nlink > 1) 757 goto close_fail; 758 if (d_unhashed(cprm.file->f_path.dentry)) 759 goto close_fail; 760 /* 761 * AK: actually i see no reason to not allow this for named 762 * pipes etc, but keep the previous behaviour for now. 763 */ 764 if (!S_ISREG(inode->i_mode)) 765 goto close_fail; 766 /* 767 * Don't dump core if the filesystem changed owner or mode 768 * of the file during file creation. This is an issue when 769 * a process dumps core while its cwd is e.g. on a vfat 770 * filesystem. 771 */ 772 if (!uid_eq(inode->i_uid, current_fsuid())) 773 goto close_fail; 774 if ((inode->i_mode & 0677) != 0600) 775 goto close_fail; 776 if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) 777 goto close_fail; 778 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) 779 goto close_fail; 780 } 781 782 /* get us an unshared descriptor table; almost always a no-op */ 783 retval = unshare_files(&displaced); 784 if (retval) 785 goto close_fail; 786 if (displaced) 787 put_files_struct(displaced); 788 if (!dump_interrupted()) { 789 file_start_write(cprm.file); 790 core_dumped = binfmt->core_dump(&cprm); 791 file_end_write(cprm.file); 792 } 793 if (ispipe && core_pipe_limit) 794 wait_for_dump_helpers(cprm.file); 795 close_fail: 796 if (cprm.file) 797 filp_close(cprm.file, NULL); 798 fail_dropcount: 799 if (ispipe) 800 atomic_dec(&core_dump_count); 801 fail_unlock: 802 kfree(argv); 803 kfree(cn.corename); 804 coredump_finish(mm, core_dumped); 805 revert_creds(old_cred); 806 fail_creds: 807 put_cred(cred); 808 fail: 809 return; 810 } 811 812 /* 813 * Core dumping helper functions. These are the only things you should 814 * do on a core-file: use only these functions to write out all the 815 * necessary info. 816 */ 817 int dump_emit(struct coredump_params *cprm, const void *addr, int nr) 818 { 819 struct file *file = cprm->file; 820 loff_t pos = file->f_pos; 821 ssize_t n; 822 if (cprm->written + nr > cprm->limit) 823 return 0; 824 while (nr) { 825 if (dump_interrupted()) 826 return 0; 827 n = __kernel_write(file, addr, nr, &pos); 828 if (n <= 0) 829 return 0; 830 file->f_pos = pos; 831 cprm->written += n; 832 cprm->pos += n; 833 nr -= n; 834 } 835 return 1; 836 } 837 EXPORT_SYMBOL(dump_emit); 838 839 int dump_skip(struct coredump_params *cprm, size_t nr) 840 { 841 static char zeroes[PAGE_SIZE]; 842 struct file *file = cprm->file; 843 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 844 if (dump_interrupted() || 845 file->f_op->llseek(file, nr, SEEK_CUR) < 0) 846 return 0; 847 cprm->pos += nr; 848 return 1; 849 } else { 850 while (nr > PAGE_SIZE) { 851 if (!dump_emit(cprm, zeroes, PAGE_SIZE)) 852 return 0; 853 nr -= PAGE_SIZE; 854 } 855 return dump_emit(cprm, zeroes, nr); 856 } 857 } 858 EXPORT_SYMBOL(dump_skip); 859 860 int dump_align(struct coredump_params *cprm, int align) 861 { 862 unsigned mod = cprm->pos & (align - 1); 863 if (align & (align - 1)) 864 return 0; 865 return mod ? dump_skip(cprm, align - mod) : 1; 866 } 867 EXPORT_SYMBOL(dump_align); 868 869 /* 870 * Ensures that file size is big enough to contain the current file 871 * postion. This prevents gdb from complaining about a truncated file 872 * if the last "write" to the file was dump_skip. 873 */ 874 void dump_truncate(struct coredump_params *cprm) 875 { 876 struct file *file = cprm->file; 877 loff_t offset; 878 879 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 880 offset = file->f_op->llseek(file, 0, SEEK_CUR); 881 if (i_size_read(file->f_mapping->host) < offset) 882 do_truncate(file->f_path.dentry, offset, 0, file); 883 } 884 } 885 EXPORT_SYMBOL(dump_truncate); 886