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 if (!(*pat_ptr)) 215 return -ENOMEM; 216 } 217 218 /* Repeat as long as we have more pattern to process and more output 219 space */ 220 while (*pat_ptr) { 221 /* 222 * Split on spaces before doing template expansion so that 223 * %e and %E don't get split if they have spaces in them 224 */ 225 if (ispipe) { 226 if (isspace(*pat_ptr)) { 227 was_space = true; 228 pat_ptr++; 229 continue; 230 } else if (was_space) { 231 was_space = false; 232 err = cn_printf(cn, "%c", '\0'); 233 if (err) 234 return err; 235 (*argv)[(*argc)++] = cn->used; 236 } 237 } 238 if (*pat_ptr != '%') { 239 err = cn_printf(cn, "%c", *pat_ptr++); 240 } else { 241 switch (*++pat_ptr) { 242 /* single % at the end, drop that */ 243 case 0: 244 goto out; 245 /* Double percent, output one percent */ 246 case '%': 247 err = cn_printf(cn, "%c", '%'); 248 break; 249 /* pid */ 250 case 'p': 251 pid_in_pattern = 1; 252 err = cn_printf(cn, "%d", 253 task_tgid_vnr(current)); 254 break; 255 /* global pid */ 256 case 'P': 257 err = cn_printf(cn, "%d", 258 task_tgid_nr(current)); 259 break; 260 case 'i': 261 err = cn_printf(cn, "%d", 262 task_pid_vnr(current)); 263 break; 264 case 'I': 265 err = cn_printf(cn, "%d", 266 task_pid_nr(current)); 267 break; 268 /* uid */ 269 case 'u': 270 err = cn_printf(cn, "%u", 271 from_kuid(&init_user_ns, 272 cred->uid)); 273 break; 274 /* gid */ 275 case 'g': 276 err = cn_printf(cn, "%u", 277 from_kgid(&init_user_ns, 278 cred->gid)); 279 break; 280 case 'd': 281 err = cn_printf(cn, "%d", 282 __get_dumpable(cprm->mm_flags)); 283 break; 284 /* signal that caused the coredump */ 285 case 's': 286 err = cn_printf(cn, "%d", 287 cprm->siginfo->si_signo); 288 break; 289 /* UNIX time of coredump */ 290 case 't': { 291 time64_t time; 292 293 time = ktime_get_real_seconds(); 294 err = cn_printf(cn, "%lld", time); 295 break; 296 } 297 /* hostname */ 298 case 'h': 299 down_read(&uts_sem); 300 err = cn_esc_printf(cn, "%s", 301 utsname()->nodename); 302 up_read(&uts_sem); 303 break; 304 /* executable */ 305 case 'e': 306 err = cn_esc_printf(cn, "%s", current->comm); 307 break; 308 case 'E': 309 err = cn_print_exe_file(cn); 310 break; 311 /* core limit size */ 312 case 'c': 313 err = cn_printf(cn, "%lu", 314 rlimit(RLIMIT_CORE)); 315 break; 316 default: 317 break; 318 } 319 ++pat_ptr; 320 } 321 322 if (err) 323 return err; 324 } 325 326 out: 327 /* Backward compatibility with core_uses_pid: 328 * 329 * If core_pattern does not include a %p (as is the default) 330 * and core_uses_pid is set, then .%pid will be appended to 331 * the filename. Do not do this for piped commands. */ 332 if (!ispipe && !pid_in_pattern && core_uses_pid) { 333 err = cn_printf(cn, ".%d", task_tgid_vnr(current)); 334 if (err) 335 return err; 336 } 337 return ispipe; 338 } 339 340 static int zap_process(struct task_struct *start, int exit_code, int flags) 341 { 342 struct task_struct *t; 343 int nr = 0; 344 345 /* ignore all signals except SIGKILL, see prepare_signal() */ 346 start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; 347 start->signal->group_exit_code = exit_code; 348 start->signal->group_stop_count = 0; 349 350 for_each_thread(start, t) { 351 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 352 if (t != current && t->mm) { 353 sigaddset(&t->pending.signal, SIGKILL); 354 signal_wake_up(t, 1); 355 nr++; 356 } 357 } 358 359 return nr; 360 } 361 362 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 363 struct core_state *core_state, int exit_code) 364 { 365 struct task_struct *g, *p; 366 unsigned long flags; 367 int nr = -EAGAIN; 368 369 spin_lock_irq(&tsk->sighand->siglock); 370 if (!signal_group_exit(tsk->signal)) { 371 mm->core_state = core_state; 372 tsk->signal->group_exit_task = tsk; 373 nr = zap_process(tsk, exit_code, 0); 374 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 375 } 376 spin_unlock_irq(&tsk->sighand->siglock); 377 if (unlikely(nr < 0)) 378 return nr; 379 380 tsk->flags |= PF_DUMPCORE; 381 if (atomic_read(&mm->mm_users) == nr + 1) 382 goto done; 383 /* 384 * We should find and kill all tasks which use this mm, and we should 385 * count them correctly into ->nr_threads. We don't take tasklist 386 * lock, but this is safe wrt: 387 * 388 * fork: 389 * None of sub-threads can fork after zap_process(leader). All 390 * processes which were created before this point should be 391 * visible to zap_threads() because copy_process() adds the new 392 * process to the tail of init_task.tasks list, and lock/unlock 393 * of ->siglock provides a memory barrier. 394 * 395 * do_exit: 396 * The caller holds mm->mmap_sem. This means that the task which 397 * uses this mm can't pass exit_mm(), so it can't exit or clear 398 * its ->mm. 399 * 400 * de_thread: 401 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 402 * we must see either old or new leader, this does not matter. 403 * However, it can change p->sighand, so lock_task_sighand(p) 404 * must be used. Since p->mm != NULL and we hold ->mmap_sem 405 * it can't fail. 406 * 407 * Note also that "g" can be the old leader with ->mm == NULL 408 * and already unhashed and thus removed from ->thread_group. 409 * This is OK, __unhash_process()->list_del_rcu() does not 410 * clear the ->next pointer, we will find the new leader via 411 * next_thread(). 412 */ 413 rcu_read_lock(); 414 for_each_process(g) { 415 if (g == tsk->group_leader) 416 continue; 417 if (g->flags & PF_KTHREAD) 418 continue; 419 420 for_each_thread(g, p) { 421 if (unlikely(!p->mm)) 422 continue; 423 if (unlikely(p->mm == mm)) { 424 lock_task_sighand(p, &flags); 425 nr += zap_process(p, exit_code, 426 SIGNAL_GROUP_EXIT); 427 unlock_task_sighand(p, &flags); 428 } 429 break; 430 } 431 } 432 rcu_read_unlock(); 433 done: 434 atomic_set(&core_state->nr_threads, nr); 435 return nr; 436 } 437 438 static int coredump_wait(int exit_code, struct core_state *core_state) 439 { 440 struct task_struct *tsk = current; 441 struct mm_struct *mm = tsk->mm; 442 int core_waiters = -EBUSY; 443 444 init_completion(&core_state->startup); 445 core_state->dumper.task = tsk; 446 core_state->dumper.next = NULL; 447 448 if (down_write_killable(&mm->mmap_sem)) 449 return -EINTR; 450 451 if (!mm->core_state) 452 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 453 up_write(&mm->mmap_sem); 454 455 if (core_waiters > 0) { 456 struct core_thread *ptr; 457 458 freezer_do_not_count(); 459 wait_for_completion(&core_state->startup); 460 freezer_count(); 461 /* 462 * Wait for all the threads to become inactive, so that 463 * all the thread context (extended register state, like 464 * fpu etc) gets copied to the memory. 465 */ 466 ptr = core_state->dumper.next; 467 while (ptr != NULL) { 468 wait_task_inactive(ptr->task, 0); 469 ptr = ptr->next; 470 } 471 } 472 473 return core_waiters; 474 } 475 476 static void coredump_finish(struct mm_struct *mm, bool core_dumped) 477 { 478 struct core_thread *curr, *next; 479 struct task_struct *task; 480 481 spin_lock_irq(¤t->sighand->siglock); 482 if (core_dumped && !__fatal_signal_pending(current)) 483 current->signal->group_exit_code |= 0x80; 484 current->signal->group_exit_task = NULL; 485 current->signal->flags = SIGNAL_GROUP_EXIT; 486 spin_unlock_irq(¤t->sighand->siglock); 487 488 next = mm->core_state->dumper.next; 489 while ((curr = next) != NULL) { 490 next = curr->next; 491 task = curr->task; 492 /* 493 * see exit_mm(), curr->task must not see 494 * ->task == NULL before we read ->next. 495 */ 496 smp_mb(); 497 curr->task = NULL; 498 wake_up_process(task); 499 } 500 501 mm->core_state = NULL; 502 } 503 504 static bool dump_interrupted(void) 505 { 506 /* 507 * SIGKILL or freezing() interrupt the coredumping. Perhaps we 508 * can do try_to_freeze() and check __fatal_signal_pending(), 509 * but then we need to teach dump_write() to restart and clear 510 * TIF_SIGPENDING. 511 */ 512 return signal_pending(current); 513 } 514 515 static void wait_for_dump_helpers(struct file *file) 516 { 517 struct pipe_inode_info *pipe = file->private_data; 518 519 pipe_lock(pipe); 520 pipe->readers++; 521 pipe->writers--; 522 wake_up_interruptible_sync(&pipe->rd_wait); 523 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 524 pipe_unlock(pipe); 525 526 /* 527 * We actually want wait_event_freezable() but then we need 528 * to clear TIF_SIGPENDING and improve dump_interrupted(). 529 */ 530 wait_event_interruptible(pipe->rd_wait, pipe->readers == 1); 531 532 pipe_lock(pipe); 533 pipe->readers--; 534 pipe->writers++; 535 pipe_unlock(pipe); 536 } 537 538 /* 539 * umh_pipe_setup 540 * helper function to customize the process used 541 * to collect the core in userspace. Specifically 542 * it sets up a pipe and installs it as fd 0 (stdin) 543 * for the process. Returns 0 on success, or 544 * PTR_ERR on failure. 545 * Note that it also sets the core limit to 1. This 546 * is a special value that we use to trap recursive 547 * core dumps 548 */ 549 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) 550 { 551 struct file *files[2]; 552 struct coredump_params *cp = (struct coredump_params *)info->data; 553 int err = create_pipe_files(files, 0); 554 if (err) 555 return err; 556 557 cp->file = files[1]; 558 559 err = replace_fd(0, files[0], 0); 560 fput(files[0]); 561 /* and disallow core files too */ 562 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; 563 564 return err; 565 } 566 567 void do_coredump(const kernel_siginfo_t *siginfo) 568 { 569 struct core_state core_state; 570 struct core_name cn; 571 struct mm_struct *mm = current->mm; 572 struct linux_binfmt * binfmt; 573 const struct cred *old_cred; 574 struct cred *cred; 575 int retval = 0; 576 int ispipe; 577 size_t *argv = NULL; 578 int argc = 0; 579 struct files_struct *displaced; 580 /* require nonrelative corefile path and be extra careful */ 581 bool need_suid_safe = false; 582 bool core_dumped = false; 583 static atomic_t core_dump_count = ATOMIC_INIT(0); 584 struct coredump_params cprm = { 585 .siginfo = siginfo, 586 .regs = signal_pt_regs(), 587 .limit = rlimit(RLIMIT_CORE), 588 /* 589 * We must use the same mm->flags while dumping core to avoid 590 * inconsistency of bit flags, since this flag is not protected 591 * by any locks. 592 */ 593 .mm_flags = mm->flags, 594 }; 595 596 audit_core_dumps(siginfo->si_signo); 597 598 binfmt = mm->binfmt; 599 if (!binfmt || !binfmt->core_dump) 600 goto fail; 601 if (!__get_dumpable(cprm.mm_flags)) 602 goto fail; 603 604 cred = prepare_creds(); 605 if (!cred) 606 goto fail; 607 /* 608 * We cannot trust fsuid as being the "true" uid of the process 609 * nor do we know its entire history. We only know it was tainted 610 * so we dump it as root in mode 2, and only into a controlled 611 * environment (pipe handler or fully qualified path). 612 */ 613 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { 614 /* Setuid core dump mode */ 615 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ 616 need_suid_safe = true; 617 } 618 619 retval = coredump_wait(siginfo->si_signo, &core_state); 620 if (retval < 0) 621 goto fail_creds; 622 623 old_cred = override_creds(cred); 624 625 ispipe = format_corename(&cn, &cprm, &argv, &argc); 626 627 if (ispipe) { 628 int argi; 629 int dump_count; 630 char **helper_argv; 631 struct subprocess_info *sub_info; 632 633 if (ispipe < 0) { 634 printk(KERN_WARNING "format_corename failed\n"); 635 printk(KERN_WARNING "Aborting core\n"); 636 goto fail_unlock; 637 } 638 639 if (cprm.limit == 1) { 640 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. 641 * 642 * Normally core limits are irrelevant to pipes, since 643 * we're not writing to the file system, but we use 644 * cprm.limit of 1 here as a special value, this is a 645 * consistent way to catch recursive crashes. 646 * We can still crash if the core_pattern binary sets 647 * RLIM_CORE = !1, but it runs as root, and can do 648 * lots of stupid things. 649 * 650 * Note that we use task_tgid_vnr here to grab the pid 651 * of the process group leader. That way we get the 652 * right pid if a thread in a multi-threaded 653 * core_pattern process dies. 654 */ 655 printk(KERN_WARNING 656 "Process %d(%s) has RLIMIT_CORE set to 1\n", 657 task_tgid_vnr(current), current->comm); 658 printk(KERN_WARNING "Aborting core\n"); 659 goto fail_unlock; 660 } 661 cprm.limit = RLIM_INFINITY; 662 663 dump_count = atomic_inc_return(&core_dump_count); 664 if (core_pipe_limit && (core_pipe_limit < dump_count)) { 665 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", 666 task_tgid_vnr(current), current->comm); 667 printk(KERN_WARNING "Skipping core dump\n"); 668 goto fail_dropcount; 669 } 670 671 helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), 672 GFP_KERNEL); 673 if (!helper_argv) { 674 printk(KERN_WARNING "%s failed to allocate memory\n", 675 __func__); 676 goto fail_dropcount; 677 } 678 for (argi = 0; argi < argc; argi++) 679 helper_argv[argi] = cn.corename + argv[argi]; 680 helper_argv[argi] = NULL; 681 682 retval = -ENOMEM; 683 sub_info = call_usermodehelper_setup(helper_argv[0], 684 helper_argv, NULL, GFP_KERNEL, 685 umh_pipe_setup, NULL, &cprm); 686 if (sub_info) 687 retval = call_usermodehelper_exec(sub_info, 688 UMH_WAIT_EXEC); 689 690 kfree(helper_argv); 691 if (retval) { 692 printk(KERN_INFO "Core dump to |%s pipe failed\n", 693 cn.corename); 694 goto close_fail; 695 } 696 } else { 697 struct inode *inode; 698 int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | 699 O_LARGEFILE | O_EXCL; 700 701 if (cprm.limit < binfmt->min_coredump) 702 goto fail_unlock; 703 704 if (need_suid_safe && cn.corename[0] != '/') { 705 printk(KERN_WARNING "Pid %d(%s) can only dump core "\ 706 "to fully qualified path!\n", 707 task_tgid_vnr(current), current->comm); 708 printk(KERN_WARNING "Skipping core dump\n"); 709 goto fail_unlock; 710 } 711 712 /* 713 * Unlink the file if it exists unless this is a SUID 714 * binary - in that case, we're running around with root 715 * privs and don't want to unlink another user's coredump. 716 */ 717 if (!need_suid_safe) { 718 /* 719 * If it doesn't exist, that's fine. If there's some 720 * other problem, we'll catch it at the filp_open(). 721 */ 722 do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); 723 } 724 725 /* 726 * There is a race between unlinking and creating the 727 * file, but if that causes an EEXIST here, that's 728 * fine - another process raced with us while creating 729 * the corefile, and the other process won. To userspace, 730 * what matters is that at least one of the two processes 731 * writes its coredump successfully, not which one. 732 */ 733 if (need_suid_safe) { 734 /* 735 * Using user namespaces, normal user tasks can change 736 * their current->fs->root to point to arbitrary 737 * directories. Since the intention of the "only dump 738 * with a fully qualified path" rule is to control where 739 * coredumps may be placed using root privileges, 740 * current->fs->root must not be used. Instead, use the 741 * root directory of init_task. 742 */ 743 struct path root; 744 745 task_lock(&init_task); 746 get_fs_root(init_task.fs, &root); 747 task_unlock(&init_task); 748 cprm.file = file_open_root(root.dentry, root.mnt, 749 cn.corename, open_flags, 0600); 750 path_put(&root); 751 } else { 752 cprm.file = filp_open(cn.corename, open_flags, 0600); 753 } 754 if (IS_ERR(cprm.file)) 755 goto fail_unlock; 756 757 inode = file_inode(cprm.file); 758 if (inode->i_nlink > 1) 759 goto close_fail; 760 if (d_unhashed(cprm.file->f_path.dentry)) 761 goto close_fail; 762 /* 763 * AK: actually i see no reason to not allow this for named 764 * pipes etc, but keep the previous behaviour for now. 765 */ 766 if (!S_ISREG(inode->i_mode)) 767 goto close_fail; 768 /* 769 * Don't dump core if the filesystem changed owner or mode 770 * of the file during file creation. This is an issue when 771 * a process dumps core while its cwd is e.g. on a vfat 772 * filesystem. 773 */ 774 if (!uid_eq(inode->i_uid, current_fsuid())) 775 goto close_fail; 776 if ((inode->i_mode & 0677) != 0600) 777 goto close_fail; 778 if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) 779 goto close_fail; 780 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) 781 goto close_fail; 782 } 783 784 /* get us an unshared descriptor table; almost always a no-op */ 785 retval = unshare_files(&displaced); 786 if (retval) 787 goto close_fail; 788 if (displaced) 789 put_files_struct(displaced); 790 if (!dump_interrupted()) { 791 /* 792 * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would 793 * have this set to NULL. 794 */ 795 if (!cprm.file) { 796 pr_info("Core dump to |%s disabled\n", cn.corename); 797 goto close_fail; 798 } 799 file_start_write(cprm.file); 800 core_dumped = binfmt->core_dump(&cprm); 801 file_end_write(cprm.file); 802 } 803 if (ispipe && core_pipe_limit) 804 wait_for_dump_helpers(cprm.file); 805 close_fail: 806 if (cprm.file) 807 filp_close(cprm.file, NULL); 808 fail_dropcount: 809 if (ispipe) 810 atomic_dec(&core_dump_count); 811 fail_unlock: 812 kfree(argv); 813 kfree(cn.corename); 814 coredump_finish(mm, core_dumped); 815 revert_creds(old_cred); 816 fail_creds: 817 put_cred(cred); 818 fail: 819 return; 820 } 821 822 /* 823 * Core dumping helper functions. These are the only things you should 824 * do on a core-file: use only these functions to write out all the 825 * necessary info. 826 */ 827 int dump_emit(struct coredump_params *cprm, const void *addr, int nr) 828 { 829 struct file *file = cprm->file; 830 loff_t pos = file->f_pos; 831 ssize_t n; 832 if (cprm->written + nr > cprm->limit) 833 return 0; 834 while (nr) { 835 if (dump_interrupted()) 836 return 0; 837 n = __kernel_write(file, addr, nr, &pos); 838 if (n <= 0) 839 return 0; 840 file->f_pos = pos; 841 cprm->written += n; 842 cprm->pos += n; 843 nr -= n; 844 } 845 return 1; 846 } 847 EXPORT_SYMBOL(dump_emit); 848 849 int dump_skip(struct coredump_params *cprm, size_t nr) 850 { 851 static char zeroes[PAGE_SIZE]; 852 struct file *file = cprm->file; 853 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 854 if (dump_interrupted() || 855 file->f_op->llseek(file, nr, SEEK_CUR) < 0) 856 return 0; 857 cprm->pos += nr; 858 return 1; 859 } else { 860 while (nr > PAGE_SIZE) { 861 if (!dump_emit(cprm, zeroes, PAGE_SIZE)) 862 return 0; 863 nr -= PAGE_SIZE; 864 } 865 return dump_emit(cprm, zeroes, nr); 866 } 867 } 868 EXPORT_SYMBOL(dump_skip); 869 870 int dump_align(struct coredump_params *cprm, int align) 871 { 872 unsigned mod = cprm->pos & (align - 1); 873 if (align & (align - 1)) 874 return 0; 875 return mod ? dump_skip(cprm, align - mod) : 1; 876 } 877 EXPORT_SYMBOL(dump_align); 878 879 /* 880 * Ensures that file size is big enough to contain the current file 881 * postion. This prevents gdb from complaining about a truncated file 882 * if the last "write" to the file was dump_skip. 883 */ 884 void dump_truncate(struct coredump_params *cprm) 885 { 886 struct file *file = cprm->file; 887 loff_t offset; 888 889 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 890 offset = file->f_op->llseek(file, 0, SEEK_CUR); 891 if (i_size_read(file->f_mapping->host) < offset) 892 do_truncate(file->f_path.dentry, offset, 0, file); 893 } 894 } 895 EXPORT_SYMBOL(dump_truncate); 896