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, bool name_only) 157 { 158 struct file *exe_file; 159 char *pathbuf, *path, *ptr; 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 if (name_only) { 179 ptr = strrchr(path, '/'); 180 if (ptr) 181 path = ptr + 1; 182 } 183 ret = cn_esc_printf(cn, "%s", path); 184 185 free_buf: 186 kfree(pathbuf); 187 put_exe_file: 188 fput(exe_file); 189 return ret; 190 } 191 192 /* format_corename will inspect the pattern parameter, and output a 193 * name into corename, which must have space for at least 194 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 195 */ 196 static int format_corename(struct core_name *cn, struct coredump_params *cprm, 197 size_t **argv, int *argc) 198 { 199 const struct cred *cred = current_cred(); 200 const char *pat_ptr = core_pattern; 201 int ispipe = (*pat_ptr == '|'); 202 bool was_space = false; 203 int pid_in_pattern = 0; 204 int err = 0; 205 206 cn->used = 0; 207 cn->corename = NULL; 208 if (expand_corename(cn, core_name_size)) 209 return -ENOMEM; 210 cn->corename[0] = '\0'; 211 212 if (ispipe) { 213 int argvs = sizeof(core_pattern) / 2; 214 (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL); 215 if (!(*argv)) 216 return -ENOMEM; 217 (*argv)[(*argc)++] = 0; 218 ++pat_ptr; 219 if (!(*pat_ptr)) 220 return -ENOMEM; 221 } 222 223 /* Repeat as long as we have more pattern to process and more output 224 space */ 225 while (*pat_ptr) { 226 /* 227 * Split on spaces before doing template expansion so that 228 * %e and %E don't get split if they have spaces in them 229 */ 230 if (ispipe) { 231 if (isspace(*pat_ptr)) { 232 if (cn->used != 0) 233 was_space = true; 234 pat_ptr++; 235 continue; 236 } else if (was_space) { 237 was_space = false; 238 err = cn_printf(cn, "%c", '\0'); 239 if (err) 240 return err; 241 (*argv)[(*argc)++] = cn->used; 242 } 243 } 244 if (*pat_ptr != '%') { 245 err = cn_printf(cn, "%c", *pat_ptr++); 246 } else { 247 switch (*++pat_ptr) { 248 /* single % at the end, drop that */ 249 case 0: 250 goto out; 251 /* Double percent, output one percent */ 252 case '%': 253 err = cn_printf(cn, "%c", '%'); 254 break; 255 /* pid */ 256 case 'p': 257 pid_in_pattern = 1; 258 err = cn_printf(cn, "%d", 259 task_tgid_vnr(current)); 260 break; 261 /* global pid */ 262 case 'P': 263 err = cn_printf(cn, "%d", 264 task_tgid_nr(current)); 265 break; 266 case 'i': 267 err = cn_printf(cn, "%d", 268 task_pid_vnr(current)); 269 break; 270 case 'I': 271 err = cn_printf(cn, "%d", 272 task_pid_nr(current)); 273 break; 274 /* uid */ 275 case 'u': 276 err = cn_printf(cn, "%u", 277 from_kuid(&init_user_ns, 278 cred->uid)); 279 break; 280 /* gid */ 281 case 'g': 282 err = cn_printf(cn, "%u", 283 from_kgid(&init_user_ns, 284 cred->gid)); 285 break; 286 case 'd': 287 err = cn_printf(cn, "%d", 288 __get_dumpable(cprm->mm_flags)); 289 break; 290 /* signal that caused the coredump */ 291 case 's': 292 err = cn_printf(cn, "%d", 293 cprm->siginfo->si_signo); 294 break; 295 /* UNIX time of coredump */ 296 case 't': { 297 time64_t time; 298 299 time = ktime_get_real_seconds(); 300 err = cn_printf(cn, "%lld", time); 301 break; 302 } 303 /* hostname */ 304 case 'h': 305 down_read(&uts_sem); 306 err = cn_esc_printf(cn, "%s", 307 utsname()->nodename); 308 up_read(&uts_sem); 309 break; 310 /* executable, could be changed by prctl PR_SET_NAME etc */ 311 case 'e': 312 err = cn_esc_printf(cn, "%s", current->comm); 313 break; 314 /* file name of executable */ 315 case 'f': 316 err = cn_print_exe_file(cn, true); 317 break; 318 case 'E': 319 err = cn_print_exe_file(cn, false); 320 break; 321 /* core limit size */ 322 case 'c': 323 err = cn_printf(cn, "%lu", 324 rlimit(RLIMIT_CORE)); 325 break; 326 default: 327 break; 328 } 329 ++pat_ptr; 330 } 331 332 if (err) 333 return err; 334 } 335 336 out: 337 /* Backward compatibility with core_uses_pid: 338 * 339 * If core_pattern does not include a %p (as is the default) 340 * and core_uses_pid is set, then .%pid will be appended to 341 * the filename. Do not do this for piped commands. */ 342 if (!ispipe && !pid_in_pattern && core_uses_pid) { 343 err = cn_printf(cn, ".%d", task_tgid_vnr(current)); 344 if (err) 345 return err; 346 } 347 return ispipe; 348 } 349 350 static int zap_process(struct task_struct *start, int exit_code, int flags) 351 { 352 struct task_struct *t; 353 int nr = 0; 354 355 /* ignore all signals except SIGKILL, see prepare_signal() */ 356 start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; 357 start->signal->group_exit_code = exit_code; 358 start->signal->group_stop_count = 0; 359 360 for_each_thread(start, t) { 361 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 362 if (t != current && t->mm) { 363 sigaddset(&t->pending.signal, SIGKILL); 364 signal_wake_up(t, 1); 365 nr++; 366 } 367 } 368 369 return nr; 370 } 371 372 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 373 struct core_state *core_state, int exit_code) 374 { 375 struct task_struct *g, *p; 376 unsigned long flags; 377 int nr = -EAGAIN; 378 379 spin_lock_irq(&tsk->sighand->siglock); 380 if (!signal_group_exit(tsk->signal)) { 381 mm->core_state = core_state; 382 tsk->signal->group_exit_task = tsk; 383 nr = zap_process(tsk, exit_code, 0); 384 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 385 } 386 spin_unlock_irq(&tsk->sighand->siglock); 387 if (unlikely(nr < 0)) 388 return nr; 389 390 tsk->flags |= PF_DUMPCORE; 391 if (atomic_read(&mm->mm_users) == nr + 1) 392 goto done; 393 /* 394 * We should find and kill all tasks which use this mm, and we should 395 * count them correctly into ->nr_threads. We don't take tasklist 396 * lock, but this is safe wrt: 397 * 398 * fork: 399 * None of sub-threads can fork after zap_process(leader). All 400 * processes which were created before this point should be 401 * visible to zap_threads() because copy_process() adds the new 402 * process to the tail of init_task.tasks list, and lock/unlock 403 * of ->siglock provides a memory barrier. 404 * 405 * do_exit: 406 * The caller holds mm->mmap_lock. This means that the task which 407 * uses this mm can't pass exit_mm(), so it can't exit or clear 408 * its ->mm. 409 * 410 * de_thread: 411 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 412 * we must see either old or new leader, this does not matter. 413 * However, it can change p->sighand, so lock_task_sighand(p) 414 * must be used. Since p->mm != NULL and we hold ->mmap_lock 415 * it can't fail. 416 * 417 * Note also that "g" can be the old leader with ->mm == NULL 418 * and already unhashed and thus removed from ->thread_group. 419 * This is OK, __unhash_process()->list_del_rcu() does not 420 * clear the ->next pointer, we will find the new leader via 421 * next_thread(). 422 */ 423 rcu_read_lock(); 424 for_each_process(g) { 425 if (g == tsk->group_leader) 426 continue; 427 if (g->flags & PF_KTHREAD) 428 continue; 429 430 for_each_thread(g, p) { 431 if (unlikely(!p->mm)) 432 continue; 433 if (unlikely(p->mm == mm)) { 434 lock_task_sighand(p, &flags); 435 nr += zap_process(p, exit_code, 436 SIGNAL_GROUP_EXIT); 437 unlock_task_sighand(p, &flags); 438 } 439 break; 440 } 441 } 442 rcu_read_unlock(); 443 done: 444 atomic_set(&core_state->nr_threads, nr); 445 return nr; 446 } 447 448 static int coredump_wait(int exit_code, struct core_state *core_state) 449 { 450 struct task_struct *tsk = current; 451 struct mm_struct *mm = tsk->mm; 452 int core_waiters = -EBUSY; 453 454 init_completion(&core_state->startup); 455 core_state->dumper.task = tsk; 456 core_state->dumper.next = NULL; 457 458 if (mmap_write_lock_killable(mm)) 459 return -EINTR; 460 461 if (!mm->core_state) 462 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 463 mmap_write_unlock(mm); 464 465 if (core_waiters > 0) { 466 struct core_thread *ptr; 467 468 freezer_do_not_count(); 469 wait_for_completion(&core_state->startup); 470 freezer_count(); 471 /* 472 * Wait for all the threads to become inactive, so that 473 * all the thread context (extended register state, like 474 * fpu etc) gets copied to the memory. 475 */ 476 ptr = core_state->dumper.next; 477 while (ptr != NULL) { 478 wait_task_inactive(ptr->task, 0); 479 ptr = ptr->next; 480 } 481 } 482 483 return core_waiters; 484 } 485 486 static void coredump_finish(struct mm_struct *mm, bool core_dumped) 487 { 488 struct core_thread *curr, *next; 489 struct task_struct *task; 490 491 spin_lock_irq(¤t->sighand->siglock); 492 if (core_dumped && !__fatal_signal_pending(current)) 493 current->signal->group_exit_code |= 0x80; 494 current->signal->group_exit_task = NULL; 495 current->signal->flags = SIGNAL_GROUP_EXIT; 496 spin_unlock_irq(¤t->sighand->siglock); 497 498 next = mm->core_state->dumper.next; 499 while ((curr = next) != NULL) { 500 next = curr->next; 501 task = curr->task; 502 /* 503 * see exit_mm(), curr->task must not see 504 * ->task == NULL before we read ->next. 505 */ 506 smp_mb(); 507 curr->task = NULL; 508 wake_up_process(task); 509 } 510 511 mm->core_state = NULL; 512 } 513 514 static bool dump_interrupted(void) 515 { 516 /* 517 * SIGKILL or freezing() interrupt the coredumping. Perhaps we 518 * can do try_to_freeze() and check __fatal_signal_pending(), 519 * but then we need to teach dump_write() to restart and clear 520 * TIF_SIGPENDING. 521 */ 522 return signal_pending(current); 523 } 524 525 static void wait_for_dump_helpers(struct file *file) 526 { 527 struct pipe_inode_info *pipe = file->private_data; 528 529 pipe_lock(pipe); 530 pipe->readers++; 531 pipe->writers--; 532 wake_up_interruptible_sync(&pipe->rd_wait); 533 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 534 pipe_unlock(pipe); 535 536 /* 537 * We actually want wait_event_freezable() but then we need 538 * to clear TIF_SIGPENDING and improve dump_interrupted(). 539 */ 540 wait_event_interruptible(pipe->rd_wait, pipe->readers == 1); 541 542 pipe_lock(pipe); 543 pipe->readers--; 544 pipe->writers++; 545 pipe_unlock(pipe); 546 } 547 548 /* 549 * umh_pipe_setup 550 * helper function to customize the process used 551 * to collect the core in userspace. Specifically 552 * it sets up a pipe and installs it as fd 0 (stdin) 553 * for the process. Returns 0 on success, or 554 * PTR_ERR on failure. 555 * Note that it also sets the core limit to 1. This 556 * is a special value that we use to trap recursive 557 * core dumps 558 */ 559 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) 560 { 561 struct file *files[2]; 562 struct coredump_params *cp = (struct coredump_params *)info->data; 563 int err = create_pipe_files(files, 0); 564 if (err) 565 return err; 566 567 cp->file = files[1]; 568 569 err = replace_fd(0, files[0], 0); 570 fput(files[0]); 571 /* and disallow core files too */ 572 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; 573 574 return err; 575 } 576 577 void do_coredump(const kernel_siginfo_t *siginfo) 578 { 579 struct core_state core_state; 580 struct core_name cn; 581 struct mm_struct *mm = current->mm; 582 struct linux_binfmt * binfmt; 583 const struct cred *old_cred; 584 struct cred *cred; 585 int retval = 0; 586 int ispipe; 587 size_t *argv = NULL; 588 int argc = 0; 589 /* require nonrelative corefile path and be extra careful */ 590 bool need_suid_safe = false; 591 bool core_dumped = false; 592 static atomic_t core_dump_count = ATOMIC_INIT(0); 593 struct coredump_params cprm = { 594 .siginfo = siginfo, 595 .regs = signal_pt_regs(), 596 .limit = rlimit(RLIMIT_CORE), 597 /* 598 * We must use the same mm->flags while dumping core to avoid 599 * inconsistency of bit flags, since this flag is not protected 600 * by any locks. 601 */ 602 .mm_flags = mm->flags, 603 }; 604 605 audit_core_dumps(siginfo->si_signo); 606 607 binfmt = mm->binfmt; 608 if (!binfmt || !binfmt->core_dump) 609 goto fail; 610 if (!__get_dumpable(cprm.mm_flags)) 611 goto fail; 612 613 cred = prepare_creds(); 614 if (!cred) 615 goto fail; 616 /* 617 * We cannot trust fsuid as being the "true" uid of the process 618 * nor do we know its entire history. We only know it was tainted 619 * so we dump it as root in mode 2, and only into a controlled 620 * environment (pipe handler or fully qualified path). 621 */ 622 if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) { 623 /* Setuid core dump mode */ 624 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ 625 need_suid_safe = true; 626 } 627 628 retval = coredump_wait(siginfo->si_signo, &core_state); 629 if (retval < 0) 630 goto fail_creds; 631 632 old_cred = override_creds(cred); 633 634 ispipe = format_corename(&cn, &cprm, &argv, &argc); 635 636 if (ispipe) { 637 int argi; 638 int dump_count; 639 char **helper_argv; 640 struct subprocess_info *sub_info; 641 642 if (ispipe < 0) { 643 printk(KERN_WARNING "format_corename failed\n"); 644 printk(KERN_WARNING "Aborting core\n"); 645 goto fail_unlock; 646 } 647 648 if (cprm.limit == 1) { 649 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1. 650 * 651 * Normally core limits are irrelevant to pipes, since 652 * we're not writing to the file system, but we use 653 * cprm.limit of 1 here as a special value, this is a 654 * consistent way to catch recursive crashes. 655 * We can still crash if the core_pattern binary sets 656 * RLIM_CORE = !1, but it runs as root, and can do 657 * lots of stupid things. 658 * 659 * Note that we use task_tgid_vnr here to grab the pid 660 * of the process group leader. That way we get the 661 * right pid if a thread in a multi-threaded 662 * core_pattern process dies. 663 */ 664 printk(KERN_WARNING 665 "Process %d(%s) has RLIMIT_CORE set to 1\n", 666 task_tgid_vnr(current), current->comm); 667 printk(KERN_WARNING "Aborting core\n"); 668 goto fail_unlock; 669 } 670 cprm.limit = RLIM_INFINITY; 671 672 dump_count = atomic_inc_return(&core_dump_count); 673 if (core_pipe_limit && (core_pipe_limit < dump_count)) { 674 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", 675 task_tgid_vnr(current), current->comm); 676 printk(KERN_WARNING "Skipping core dump\n"); 677 goto fail_dropcount; 678 } 679 680 helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv), 681 GFP_KERNEL); 682 if (!helper_argv) { 683 printk(KERN_WARNING "%s failed to allocate memory\n", 684 __func__); 685 goto fail_dropcount; 686 } 687 for (argi = 0; argi < argc; argi++) 688 helper_argv[argi] = cn.corename + argv[argi]; 689 helper_argv[argi] = NULL; 690 691 retval = -ENOMEM; 692 sub_info = call_usermodehelper_setup(helper_argv[0], 693 helper_argv, NULL, GFP_KERNEL, 694 umh_pipe_setup, NULL, &cprm); 695 if (sub_info) 696 retval = call_usermodehelper_exec(sub_info, 697 UMH_WAIT_EXEC); 698 699 kfree(helper_argv); 700 if (retval) { 701 printk(KERN_INFO "Core dump to |%s pipe failed\n", 702 cn.corename); 703 goto close_fail; 704 } 705 } else { 706 struct user_namespace *mnt_userns; 707 struct inode *inode; 708 int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW | 709 O_LARGEFILE | O_EXCL; 710 711 if (cprm.limit < binfmt->min_coredump) 712 goto fail_unlock; 713 714 if (need_suid_safe && cn.corename[0] != '/') { 715 printk(KERN_WARNING "Pid %d(%s) can only dump core "\ 716 "to fully qualified path!\n", 717 task_tgid_vnr(current), current->comm); 718 printk(KERN_WARNING "Skipping core dump\n"); 719 goto fail_unlock; 720 } 721 722 /* 723 * Unlink the file if it exists unless this is a SUID 724 * binary - in that case, we're running around with root 725 * privs and don't want to unlink another user's coredump. 726 */ 727 if (!need_suid_safe) { 728 /* 729 * If it doesn't exist, that's fine. If there's some 730 * other problem, we'll catch it at the filp_open(). 731 */ 732 do_unlinkat(AT_FDCWD, getname_kernel(cn.corename)); 733 } 734 735 /* 736 * There is a race between unlinking and creating the 737 * file, but if that causes an EEXIST here, that's 738 * fine - another process raced with us while creating 739 * the corefile, and the other process won. To userspace, 740 * what matters is that at least one of the two processes 741 * writes its coredump successfully, not which one. 742 */ 743 if (need_suid_safe) { 744 /* 745 * Using user namespaces, normal user tasks can change 746 * their current->fs->root to point to arbitrary 747 * directories. Since the intention of the "only dump 748 * with a fully qualified path" rule is to control where 749 * coredumps may be placed using root privileges, 750 * current->fs->root must not be used. Instead, use the 751 * root directory of init_task. 752 */ 753 struct path root; 754 755 task_lock(&init_task); 756 get_fs_root(init_task.fs, &root); 757 task_unlock(&init_task); 758 cprm.file = file_open_root(root.dentry, root.mnt, 759 cn.corename, open_flags, 0600); 760 path_put(&root); 761 } else { 762 cprm.file = filp_open(cn.corename, open_flags, 0600); 763 } 764 if (IS_ERR(cprm.file)) 765 goto fail_unlock; 766 767 inode = file_inode(cprm.file); 768 if (inode->i_nlink > 1) 769 goto close_fail; 770 if (d_unhashed(cprm.file->f_path.dentry)) 771 goto close_fail; 772 /* 773 * AK: actually i see no reason to not allow this for named 774 * pipes etc, but keep the previous behaviour for now. 775 */ 776 if (!S_ISREG(inode->i_mode)) 777 goto close_fail; 778 /* 779 * Don't dump core if the filesystem changed owner or mode 780 * of the file during file creation. This is an issue when 781 * a process dumps core while its cwd is e.g. on a vfat 782 * filesystem. 783 */ 784 mnt_userns = file_mnt_user_ns(cprm.file); 785 if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid())) 786 goto close_fail; 787 if ((inode->i_mode & 0677) != 0600) 788 goto close_fail; 789 if (!(cprm.file->f_mode & FMODE_CAN_WRITE)) 790 goto close_fail; 791 if (do_truncate(mnt_userns, cprm.file->f_path.dentry, 792 0, 0, cprm.file)) 793 goto close_fail; 794 } 795 796 /* get us an unshared descriptor table; almost always a no-op */ 797 /* The cell spufs coredump code reads the file descriptor tables */ 798 retval = unshare_files(); 799 if (retval) 800 goto close_fail; 801 if (!dump_interrupted()) { 802 /* 803 * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would 804 * have this set to NULL. 805 */ 806 if (!cprm.file) { 807 pr_info("Core dump to |%s disabled\n", cn.corename); 808 goto close_fail; 809 } 810 file_start_write(cprm.file); 811 core_dumped = binfmt->core_dump(&cprm); 812 file_end_write(cprm.file); 813 } 814 if (ispipe && core_pipe_limit) 815 wait_for_dump_helpers(cprm.file); 816 close_fail: 817 if (cprm.file) 818 filp_close(cprm.file, NULL); 819 fail_dropcount: 820 if (ispipe) 821 atomic_dec(&core_dump_count); 822 fail_unlock: 823 kfree(argv); 824 kfree(cn.corename); 825 coredump_finish(mm, core_dumped); 826 revert_creds(old_cred); 827 fail_creds: 828 put_cred(cred); 829 fail: 830 return; 831 } 832 833 /* 834 * Core dumping helper functions. These are the only things you should 835 * do on a core-file: use only these functions to write out all the 836 * necessary info. 837 */ 838 int dump_emit(struct coredump_params *cprm, const void *addr, int nr) 839 { 840 struct file *file = cprm->file; 841 loff_t pos = file->f_pos; 842 ssize_t n; 843 if (cprm->written + nr > cprm->limit) 844 return 0; 845 846 847 if (dump_interrupted()) 848 return 0; 849 n = __kernel_write(file, addr, nr, &pos); 850 if (n != nr) 851 return 0; 852 file->f_pos = pos; 853 cprm->written += n; 854 cprm->pos += n; 855 856 return 1; 857 } 858 EXPORT_SYMBOL(dump_emit); 859 860 int dump_skip(struct coredump_params *cprm, size_t nr) 861 { 862 static char zeroes[PAGE_SIZE]; 863 struct file *file = cprm->file; 864 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 865 if (dump_interrupted() || 866 file->f_op->llseek(file, nr, SEEK_CUR) < 0) 867 return 0; 868 cprm->pos += nr; 869 return 1; 870 } else { 871 while (nr > PAGE_SIZE) { 872 if (!dump_emit(cprm, zeroes, PAGE_SIZE)) 873 return 0; 874 nr -= PAGE_SIZE; 875 } 876 return dump_emit(cprm, zeroes, nr); 877 } 878 } 879 EXPORT_SYMBOL(dump_skip); 880 881 #ifdef CONFIG_ELF_CORE 882 int dump_user_range(struct coredump_params *cprm, unsigned long start, 883 unsigned long len) 884 { 885 unsigned long addr; 886 887 for (addr = start; addr < start + len; addr += PAGE_SIZE) { 888 struct page *page; 889 int stop; 890 891 /* 892 * To avoid having to allocate page tables for virtual address 893 * ranges that have never been used yet, and also to make it 894 * easy to generate sparse core files, use a helper that returns 895 * NULL when encountering an empty page table entry that would 896 * otherwise have been filled with the zero page. 897 */ 898 page = get_dump_page(addr); 899 if (page) { 900 void *kaddr = kmap_local_page(page); 901 902 stop = !dump_emit(cprm, kaddr, PAGE_SIZE); 903 kunmap_local(kaddr); 904 put_page(page); 905 } else { 906 stop = !dump_skip(cprm, PAGE_SIZE); 907 } 908 if (stop) 909 return 0; 910 } 911 return 1; 912 } 913 #endif 914 915 int dump_align(struct coredump_params *cprm, int align) 916 { 917 unsigned mod = cprm->pos & (align - 1); 918 if (align & (align - 1)) 919 return 0; 920 return mod ? dump_skip(cprm, align - mod) : 1; 921 } 922 EXPORT_SYMBOL(dump_align); 923 924 /* 925 * Ensures that file size is big enough to contain the current file 926 * postion. This prevents gdb from complaining about a truncated file 927 * if the last "write" to the file was dump_skip. 928 */ 929 void dump_truncate(struct coredump_params *cprm) 930 { 931 struct file *file = cprm->file; 932 loff_t offset; 933 934 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 935 offset = file->f_op->llseek(file, 0, SEEK_CUR); 936 if (i_size_read(file->f_mapping->host) < offset) 937 do_truncate(file_mnt_user_ns(file), file->f_path.dentry, 938 offset, 0, file); 939 } 940 } 941 EXPORT_SYMBOL(dump_truncate); 942 943 /* 944 * The purpose of always_dump_vma() is to make sure that special kernel mappings 945 * that are useful for post-mortem analysis are included in every core dump. 946 * In that way we ensure that the core dump is fully interpretable later 947 * without matching up the same kernel and hardware config to see what PC values 948 * meant. These special mappings include - vDSO, vsyscall, and other 949 * architecture specific mappings 950 */ 951 static bool always_dump_vma(struct vm_area_struct *vma) 952 { 953 /* Any vsyscall mappings? */ 954 if (vma == get_gate_vma(vma->vm_mm)) 955 return true; 956 957 /* 958 * Assume that all vmas with a .name op should always be dumped. 959 * If this changes, a new vm_ops field can easily be added. 960 */ 961 if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma)) 962 return true; 963 964 /* 965 * arch_vma_name() returns non-NULL for special architecture mappings, 966 * such as vDSO sections. 967 */ 968 if (arch_vma_name(vma)) 969 return true; 970 971 return false; 972 } 973 974 /* 975 * Decide how much of @vma's contents should be included in a core dump. 976 */ 977 static unsigned long vma_dump_size(struct vm_area_struct *vma, 978 unsigned long mm_flags) 979 { 980 #define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type)) 981 982 /* always dump the vdso and vsyscall sections */ 983 if (always_dump_vma(vma)) 984 goto whole; 985 986 if (vma->vm_flags & VM_DONTDUMP) 987 return 0; 988 989 /* support for DAX */ 990 if (vma_is_dax(vma)) { 991 if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED)) 992 goto whole; 993 if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE)) 994 goto whole; 995 return 0; 996 } 997 998 /* Hugetlb memory check */ 999 if (is_vm_hugetlb_page(vma)) { 1000 if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED)) 1001 goto whole; 1002 if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE)) 1003 goto whole; 1004 return 0; 1005 } 1006 1007 /* Do not dump I/O mapped devices or special mappings */ 1008 if (vma->vm_flags & VM_IO) 1009 return 0; 1010 1011 /* By default, dump shared memory if mapped from an anonymous file. */ 1012 if (vma->vm_flags & VM_SHARED) { 1013 if (file_inode(vma->vm_file)->i_nlink == 0 ? 1014 FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED)) 1015 goto whole; 1016 return 0; 1017 } 1018 1019 /* Dump segments that have been written to. */ 1020 if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE)) 1021 goto whole; 1022 if (vma->vm_file == NULL) 1023 return 0; 1024 1025 if (FILTER(MAPPED_PRIVATE)) 1026 goto whole; 1027 1028 /* 1029 * If this is the beginning of an executable file mapping, 1030 * dump the first page to aid in determining what was mapped here. 1031 */ 1032 if (FILTER(ELF_HEADERS) && 1033 vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) && 1034 (READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0) 1035 return PAGE_SIZE; 1036 1037 #undef FILTER 1038 1039 return 0; 1040 1041 whole: 1042 return vma->vm_end - vma->vm_start; 1043 } 1044 1045 static struct vm_area_struct *first_vma(struct task_struct *tsk, 1046 struct vm_area_struct *gate_vma) 1047 { 1048 struct vm_area_struct *ret = tsk->mm->mmap; 1049 1050 if (ret) 1051 return ret; 1052 return gate_vma; 1053 } 1054 1055 /* 1056 * Helper function for iterating across a vma list. It ensures that the caller 1057 * will visit `gate_vma' prior to terminating the search. 1058 */ 1059 static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma, 1060 struct vm_area_struct *gate_vma) 1061 { 1062 struct vm_area_struct *ret; 1063 1064 ret = this_vma->vm_next; 1065 if (ret) 1066 return ret; 1067 if (this_vma == gate_vma) 1068 return NULL; 1069 return gate_vma; 1070 } 1071 1072 /* 1073 * Under the mmap_lock, take a snapshot of relevant information about the task's 1074 * VMAs. 1075 */ 1076 int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count, 1077 struct core_vma_metadata **vma_meta, 1078 size_t *vma_data_size_ptr) 1079 { 1080 struct vm_area_struct *vma, *gate_vma; 1081 struct mm_struct *mm = current->mm; 1082 int i; 1083 size_t vma_data_size = 0; 1084 1085 /* 1086 * Once the stack expansion code is fixed to not change VMA bounds 1087 * under mmap_lock in read mode, this can be changed to take the 1088 * mmap_lock in read mode. 1089 */ 1090 if (mmap_write_lock_killable(mm)) 1091 return -EINTR; 1092 1093 gate_vma = get_gate_vma(mm); 1094 *vma_count = mm->map_count + (gate_vma ? 1 : 0); 1095 1096 *vma_meta = kvmalloc_array(*vma_count, sizeof(**vma_meta), GFP_KERNEL); 1097 if (!*vma_meta) { 1098 mmap_write_unlock(mm); 1099 return -ENOMEM; 1100 } 1101 1102 for (i = 0, vma = first_vma(current, gate_vma); vma != NULL; 1103 vma = next_vma(vma, gate_vma), i++) { 1104 struct core_vma_metadata *m = (*vma_meta) + i; 1105 1106 m->start = vma->vm_start; 1107 m->end = vma->vm_end; 1108 m->flags = vma->vm_flags; 1109 m->dump_size = vma_dump_size(vma, cprm->mm_flags); 1110 1111 vma_data_size += m->dump_size; 1112 } 1113 1114 mmap_write_unlock(mm); 1115 1116 if (WARN_ON(i != *vma_count)) 1117 return -EFAULT; 1118 1119 *vma_data_size_ptr = vma_data_size; 1120 return 0; 1121 } 1122