1 /*
2 * Copyright (c) 2000-2021 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /* Copyright (c) 1991 NeXT Computer, Inc. All rights reserved.
29 *
30 * File: bsd/kern/kern_core.c
31 *
32 * This file contains machine independent code for performing core dumps.
33 *
34 */
35 #if CONFIG_COREDUMP
36
37 #include <mach/vm_param.h>
38 #include <mach/thread_status.h>
39 #include <sys/content_protection.h>
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/signalvar.h>
43 #include <sys/resourcevar.h>
44 #include <sys/namei.h>
45 #include <sys/vnode_internal.h>
46 #include <sys/proc_internal.h>
47 #include <sys/kauth.h>
48 #include <sys/timeb.h>
49 #include <sys/times.h>
50 #include <sys/acct.h>
51 #include <sys/file_internal.h>
52 #include <sys/uio.h>
53 #include <sys/kernel.h>
54 #include <sys/stat.h>
55
56 #include <mach-o/loader.h>
57 #include <mach/vm_region.h>
58 #include <mach/vm_statistics.h>
59
60 #include <vm/vm_kern.h>
61 #include <vm/vm_protos.h> /* last */
62 #include <vm/vm_map.h> /* current_map() */
63 #include <mach/mach_vm.h> /* mach_vm_region_recurse() */
64 #include <mach/task.h> /* task_suspend() */
65 #include <kern/task.h> /* get_task_numacts() */
66
67 #include <security/audit/audit.h>
68
69 #if CONFIG_MACF
70 #include <security/mac_framework.h>
71 #endif /* CONFIG_MACF */
72
73 typedef struct {
74 int flavor; /* the number for this flavor */
75 mach_msg_type_number_t count; /* count of ints in this flavor */
76 } mythread_state_flavor_t;
77
78 #if defined (__i386__) || defined (__x86_64__)
79 mythread_state_flavor_t thread_flavor_array[] = {
80 {x86_THREAD_STATE, x86_THREAD_STATE_COUNT},
81 {x86_FLOAT_STATE, x86_FLOAT_STATE_COUNT},
82 {x86_EXCEPTION_STATE, x86_EXCEPTION_STATE_COUNT},
83 };
84 int mynum_flavors = 3;
85 #elif defined (__arm__)
86 mythread_state_flavor_t thread_flavor_array[] = {
87 {ARM_THREAD_STATE, ARM_THREAD_STATE_COUNT},
88 {ARM_VFP_STATE, ARM_VFP_STATE_COUNT},
89 {ARM_EXCEPTION_STATE, ARM_EXCEPTION_STATE_COUNT}
90 };
91 int mynum_flavors = 3;
92
93 #elif defined (__arm64__)
94 mythread_state_flavor_t thread_flavor_array[] = {
95 {ARM_THREAD_STATE64, ARM_THREAD_STATE64_COUNT},
96 /* ARM64_TODO: VFP */
97 {ARM_EXCEPTION_STATE64, ARM_EXCEPTION_STATE64_COUNT}
98 };
99 int mynum_flavors = 2;
100 #else
101 #error architecture not supported
102 #endif
103
104
105 typedef struct {
106 vm_offset_t header;
107 size_t hoffset;
108 mythread_state_flavor_t *flavors;
109 size_t tstate_size;
110 size_t flavor_count;
111 } tir_t;
112
113 extern int freespace_mb(vnode_t vp);
114
115 /* XXX not in a Mach header anywhere */
116 kern_return_t thread_getstatus(thread_t act, int flavor,
117 thread_state_t tstate, mach_msg_type_number_t *count);
118 void task_act_iterate_wth_args(task_t, void (*)(thread_t, void *), void *);
119
120 #ifdef SECURE_KERNEL
121 __XNU_PRIVATE_EXTERN int do_coredump = 0; /* default: don't dump cores */
122 #else
123 __XNU_PRIVATE_EXTERN int do_coredump = 1; /* default: dump cores */
124 #endif
125 __XNU_PRIVATE_EXTERN int sugid_coredump = 0; /* default: but not SGUID binaries */
126
127
128 /* cpu_type returns only the most generic indication of the current CPU. */
129 /* in a core we want to know the kind of process. */
130
131 static cpu_type_t
process_cpu_type(proc_t core_proc)132 process_cpu_type(proc_t core_proc)
133 {
134 cpu_type_t what_we_think;
135 #if defined (__i386__) || defined (__x86_64__)
136 if (IS_64BIT_PROCESS(core_proc)) {
137 what_we_think = CPU_TYPE_X86_64;
138 } else {
139 what_we_think = CPU_TYPE_I386;
140 }
141 #elif defined (__arm__) || defined(__arm64__)
142 if (IS_64BIT_PROCESS(core_proc)) {
143 what_we_think = CPU_TYPE_ARM64;
144 } else {
145 what_we_think = CPU_TYPE_ARM;
146 }
147 #endif
148
149 return what_we_think;
150 }
151
152 static cpu_type_t
process_cpu_subtype(proc_t core_proc)153 process_cpu_subtype(proc_t core_proc)
154 {
155 cpu_type_t what_we_think;
156 #if defined (__i386__) || defined (__x86_64__)
157 if (IS_64BIT_PROCESS(core_proc)) {
158 what_we_think = CPU_SUBTYPE_X86_64_ALL;
159 } else {
160 what_we_think = CPU_SUBTYPE_I386_ALL;
161 }
162 #elif defined (__arm__) || defined(__arm64__)
163 if (IS_64BIT_PROCESS(core_proc)) {
164 what_we_think = CPU_SUBTYPE_ARM64_ALL;
165 } else {
166 what_we_think = CPU_SUBTYPE_ARM_ALL;
167 }
168 #endif
169 return what_we_think;
170 }
171
172 static void
collectth_state(thread_t th_act,void * tirp)173 collectth_state(thread_t th_act, void *tirp)
174 {
175 vm_offset_t header;
176 size_t hoffset, i;
177 mythread_state_flavor_t *flavors;
178 struct thread_command *tc;
179 tir_t *t = (tir_t *)tirp;
180
181 /*
182 * Fill in thread command structure.
183 */
184 header = t->header;
185 hoffset = t->hoffset;
186 flavors = t->flavors;
187
188 tc = (struct thread_command *) (header + hoffset);
189 tc->cmd = LC_THREAD;
190 tc->cmdsize = (uint32_t)(sizeof(struct thread_command)
191 + t->tstate_size);
192 hoffset += sizeof(struct thread_command);
193 /*
194 * Follow with a struct thread_state_flavor and
195 * the appropriate thread state struct for each
196 * thread state flavor.
197 */
198 for (i = 0; i < t->flavor_count; i++) {
199 *(mythread_state_flavor_t *)(header + hoffset) =
200 flavors[i];
201 hoffset += sizeof(mythread_state_flavor_t);
202 thread_getstatus(th_act, flavors[i].flavor,
203 (thread_state_t)(header + hoffset),
204 &flavors[i].count);
205 hoffset += flavors[i].count * sizeof(int);
206 }
207
208 t->hoffset = hoffset;
209 }
210
211 /*
212 * coredump
213 *
214 * Description: Create a core image on the file "core" for the process
215 * indicated
216 *
217 * Parameters: core_proc Process to dump core [*]
218 * reserve_mb If non-zero, leave filesystem with
219 * at least this much free space.
220 * coredump_flags Extra options (ignore rlimit, run fsync)
221 *
222 * Returns: 0 Success
223 * !0 Failure errno
224 *
225 * IMPORTANT: This function can only be called on the current process, due
226 * to assumptions below; see variable declaration section for
227 * details.
228 */
229 #define MAX_TSTATE_FLAVORS 10
230 int
coredump(proc_t core_proc,uint32_t reserve_mb,int coredump_flags)231 coredump(proc_t core_proc, uint32_t reserve_mb, int coredump_flags)
232 {
233 /* Begin assumptions that limit us to only the current process */
234 vfs_context_t ctx = vfs_context_current();
235 vm_map_t map = current_map();
236 task_t task = current_task();
237 /* End assumptions */
238 kauth_cred_t cred = vfs_context_ucred(ctx);
239 int error = 0;
240 struct vnode_attr va;
241 size_t thread_count, segment_count;
242 size_t command_size, header_size, tstate_size;
243 size_t hoffset;
244 off_t foffset;
245 mach_vm_offset_t vmoffset;
246 vm_offset_t header;
247 mach_vm_size_t vmsize;
248 vm_prot_t prot;
249 vm_prot_t maxprot;
250 int error1 = 0;
251 char stack_name[MAXCOMLEN + 6];
252 char *alloced_name = NULL;
253 char *name = NULL;
254 mythread_state_flavor_t flavors[MAX_TSTATE_FLAVORS];
255 vm_size_t mapsize;
256 size_t i;
257 uint32_t nesting_depth = 0;
258 kern_return_t kret;
259 struct vm_region_submap_info_64 vbr;
260 mach_msg_type_number_t vbrcount = 0;
261 tir_t tir1;
262 struct vnode * vp;
263 struct mach_header *mh = NULL; /* protected by is_64 */
264 struct mach_header_64 *mh64 = NULL; /* protected by is_64 */
265 int is_64 = 0;
266 size_t mach_header_sz = sizeof(struct mach_header);
267 size_t segment_command_sz = sizeof(struct segment_command);
268
269 if (current_proc() != core_proc) {
270 panic("coredump() called against proc that is not current_proc: %p", core_proc);
271 }
272
273 if (do_coredump == 0 || /* Not dumping at all */
274 ((sugid_coredump == 0) && /* Not dumping SUID/SGID binaries */
275 ((kauth_cred_getsvuid(cred) != kauth_cred_getruid(cred)) ||
276 (kauth_cred_getsvgid(cred) != kauth_cred_getrgid(cred))))) {
277 error = EFAULT;
278 goto out2;
279 }
280
281 #if CONFIG_MACF
282 error = mac_proc_check_dump_core(core_proc);
283 if (error != 0) {
284 goto out2;
285 }
286 #endif
287
288 if (IS_64BIT_PROCESS(core_proc)) {
289 is_64 = 1;
290 mach_header_sz = sizeof(struct mach_header_64);
291 segment_command_sz = sizeof(struct segment_command_64);
292 }
293
294 mapsize = get_vmmap_size(map);
295
296 if (((coredump_flags & COREDUMP_IGNORE_ULIMIT) == 0) &&
297 (mapsize >= proc_limitgetcur(core_proc, RLIMIT_CORE))) {
298 error = EFAULT;
299 goto out2;
300 }
301
302 (void) task_suspend_internal(task);
303
304 alloced_name = zalloc_flags(ZV_NAMEI, Z_NOWAIT | Z_ZERO);
305
306 /* create name according to sysctl'able format string */
307 /* if name creation fails, fall back to historical behaviour... */
308 if (alloced_name == NULL ||
309 proc_core_name(core_proc->p_comm, kauth_cred_getuid(cred),
310 proc_getpid(core_proc), alloced_name, MAXPATHLEN)) {
311 snprintf(stack_name, sizeof(stack_name),
312 "/cores/core.%d", proc_getpid(core_proc));
313 name = stack_name;
314 } else {
315 name = alloced_name;
316 }
317
318 if ((error = vnode_open(name, (O_CREAT | FWRITE | O_NOFOLLOW), S_IRUSR, VNODE_LOOKUP_NOFOLLOW, &vp, ctx))) {
319 goto out2;
320 }
321
322 VATTR_INIT(&va);
323 VATTR_WANTED(&va, va_nlink);
324 /* Don't dump to non-regular files or files with links. */
325 if (vp->v_type != VREG ||
326 vnode_getattr(vp, &va, ctx) || va.va_nlink != 1) {
327 error = EFAULT;
328 goto out;
329 }
330
331 VATTR_INIT(&va); /* better to do it here than waste more stack in vnode_setsize */
332 VATTR_SET(&va, va_data_size, 0);
333 if (core_proc == initproc) {
334 VATTR_SET(&va, va_dataprotect_class, PROTECTION_CLASS_D);
335 }
336 vnode_setattr(vp, &va, ctx);
337 core_proc->p_acflag |= ACORE;
338
339 if ((reserve_mb > 0) &&
340 ((freespace_mb(vp) - (mapsize >> 20)) < reserve_mb)) {
341 error = ENOSPC;
342 goto out;
343 }
344
345 /*
346 * If the task is modified while dumping the file
347 * (e.g., changes in threads or VM, the resulting
348 * file will not necessarily be correct.
349 */
350
351 thread_count = get_task_numacts(task);
352 segment_count = get_vmmap_entries(map); /* XXX */
353 tir1.flavor_count = sizeof(thread_flavor_array) / sizeof(mythread_state_flavor_t);
354 bcopy(thread_flavor_array, flavors, sizeof(thread_flavor_array));
355 tstate_size = 0;
356 for (i = 0; i < tir1.flavor_count; i++) {
357 tstate_size += sizeof(mythread_state_flavor_t) +
358 (flavors[i].count * sizeof(int));
359 }
360
361 {
362 size_t lhs;
363 size_t rhs;
364
365 /* lhs = segment_count * segment_command_sz */
366 if (os_mul_overflow(segment_count, segment_command_sz, &lhs)) {
367 error = ENOMEM;
368 goto out;
369 }
370
371 /* rhs = (tstate_size + sizeof(struct thread_command)) * thread_count */
372 if (os_add_and_mul_overflow(tstate_size, sizeof(struct thread_command), thread_count, &rhs)) {
373 error = ENOMEM;
374 goto out;
375 }
376
377 /* command_size = lhs + rhs */
378 if (os_add_overflow(lhs, rhs, &command_size)) {
379 error = ENOMEM;
380 goto out;
381 }
382 }
383
384 if (os_add_overflow(command_size, mach_header_sz, &header_size)) {
385 error = ENOMEM;
386 goto out;
387 }
388
389 if (kmem_alloc_flags(kernel_map, &header, (vm_size_t)header_size, VM_KERN_MEMORY_DIAG, KMA_ZERO) != KERN_SUCCESS) {
390 error = ENOMEM;
391 goto out;
392 }
393
394 /*
395 * Set up Mach-O header.
396 */
397 if (is_64) {
398 mh64 = (struct mach_header_64 *)header;
399 mh64->magic = MH_MAGIC_64;
400 mh64->cputype = process_cpu_type(core_proc);
401 mh64->cpusubtype = process_cpu_subtype(core_proc);
402 mh64->filetype = MH_CORE;
403 mh64->ncmds = (uint32_t)(segment_count + thread_count);
404 mh64->sizeofcmds = (uint32_t)command_size;
405 } else {
406 mh = (struct mach_header *)header;
407 mh->magic = MH_MAGIC;
408 mh->cputype = process_cpu_type(core_proc);
409 mh->cpusubtype = process_cpu_subtype(core_proc);
410 mh->filetype = MH_CORE;
411 mh->ncmds = (uint32_t)(segment_count + thread_count);
412 mh->sizeofcmds = (uint32_t)command_size;
413 }
414
415 hoffset = mach_header_sz; /* offset into header */
416 foffset = round_page(header_size); /* offset into file */
417 vmoffset = MACH_VM_MIN_ADDRESS; /* offset into VM */
418
419 /*
420 * We use to check for an error, here, now we try and get
421 * as much as we can
422 */
423 while (segment_count > 0) {
424 struct segment_command *sc;
425 struct segment_command_64 *sc64;
426
427 /*
428 * Get region information for next region.
429 */
430
431 while (1) {
432 vbrcount = VM_REGION_SUBMAP_INFO_COUNT_64;
433 if ((kret = mach_vm_region_recurse(map,
434 &vmoffset, &vmsize, &nesting_depth,
435 (vm_region_recurse_info_t)&vbr,
436 &vbrcount)) != KERN_SUCCESS) {
437 break;
438 }
439 /*
440 * If we get a valid mapping back, but we're dumping
441 * a 32 bit process, and it's over the allowable
442 * address space of a 32 bit process, it's the same
443 * as if mach_vm_region_recurse() failed.
444 */
445 if (!(is_64) &&
446 (vmoffset + vmsize > VM_MAX_ADDRESS)) {
447 kret = KERN_INVALID_ADDRESS;
448 break;
449 }
450 if (vbr.is_submap) {
451 nesting_depth++;
452 continue;
453 } else {
454 break;
455 }
456 }
457 if (kret != KERN_SUCCESS) {
458 break;
459 }
460
461 prot = vbr.protection;
462 maxprot = vbr.max_protection;
463
464 if ((prot | maxprot) == VM_PROT_NONE) {
465 /*
466 * Elide unreadable (likely reserved) segments
467 */
468 vmoffset += vmsize;
469 continue;
470 }
471
472 /*
473 * Try as hard as possible to get read access to the data.
474 */
475 if ((prot & VM_PROT_READ) == 0) {
476 mach_vm_protect(map, vmoffset, vmsize, FALSE,
477 prot | VM_PROT_READ);
478 }
479
480 /*
481 * But only try and perform the write if we can read it.
482 */
483 int64_t fsize = ((maxprot & VM_PROT_READ) == VM_PROT_READ
484 && vbr.user_tag != VM_MEMORY_IOKIT
485 && coredumpok(map, vmoffset)) ? vmsize : 0;
486
487 if (fsize) {
488 int64_t resid = 0;
489 const enum uio_seg sflg = IS_64BIT_PROCESS(core_proc) ?
490 UIO_USERSPACE64 : UIO_USERSPACE32;
491
492 error = vn_rdwr_64(UIO_WRITE, vp, vmoffset, fsize,
493 foffset, sflg, IO_NOCACHE | IO_NODELOCKED | IO_UNIT,
494 cred, &resid, core_proc);
495
496 if (error) {
497 /*
498 * Mark segment as empty
499 */
500 fsize = 0;
501 } else if (resid) {
502 /*
503 * Partial write. Extend the file size so
504 * that the segment command contains a valid
505 * range of offsets, possibly creating a hole.
506 */
507 VATTR_INIT(&va);
508 VATTR_SET(&va, va_data_size, foffset + fsize);
509 vnode_setattr(vp, &va, ctx);
510 }
511 }
512
513 /*
514 * Fill in segment command structure.
515 */
516
517 if (is_64) {
518 sc64 = (struct segment_command_64 *)(header + hoffset);
519 sc64->cmd = LC_SEGMENT_64;
520 sc64->cmdsize = sizeof(struct segment_command_64);
521 /* segment name is zeroed by kmem_alloc */
522 sc64->segname[0] = 0;
523 sc64->vmaddr = vmoffset;
524 sc64->vmsize = vmsize;
525 sc64->fileoff = foffset;
526 sc64->filesize = fsize;
527 sc64->maxprot = maxprot;
528 sc64->initprot = prot;
529 sc64->nsects = 0;
530 sc64->flags = 0;
531 } else {
532 sc = (struct segment_command *) (header + hoffset);
533 sc->cmd = LC_SEGMENT;
534 sc->cmdsize = sizeof(struct segment_command);
535 /* segment name is zeroed by kmem_alloc */
536 sc->segname[0] = 0;
537 sc->vmaddr = CAST_DOWN_EXPLICIT(uint32_t, vmoffset);
538 sc->vmsize = CAST_DOWN_EXPLICIT(uint32_t, vmsize);
539 sc->fileoff = CAST_DOWN_EXPLICIT(uint32_t, foffset); /* will never truncate */
540 sc->filesize = CAST_DOWN_EXPLICIT(uint32_t, fsize); /* will never truncate */
541 sc->maxprot = maxprot;
542 sc->initprot = prot;
543 sc->nsects = 0;
544 sc->flags = 0;
545 }
546
547 hoffset += segment_command_sz;
548 foffset += fsize;
549 vmoffset += vmsize;
550 segment_count--;
551 }
552
553 /*
554 * If there are remaining segments which have not been written
555 * out because break in the loop above, then they were not counted
556 * because they exceed the real address space of the executable
557 * type: remove them from the header's count. This is OK, since
558 * we are allowed to have a sparse area following the segments.
559 */
560 if (is_64) {
561 mh64->ncmds -= segment_count;
562 mh64->sizeofcmds -= segment_count * segment_command_sz;
563 } else {
564 mh->ncmds -= segment_count;
565 mh->sizeofcmds -= segment_count * segment_command_sz;
566 }
567
568 tir1.header = header;
569 tir1.hoffset = hoffset;
570 tir1.flavors = flavors;
571 tir1.tstate_size = tstate_size;
572 task_act_iterate_wth_args(task, collectth_state, &tir1);
573
574 /*
575 * Write out the Mach header at the beginning of the
576 * file. OK to use a 32 bit write for this.
577 */
578 error = vn_rdwr(UIO_WRITE, vp, (caddr_t)header, (int)MIN(header_size, INT_MAX), (off_t)0,
579 UIO_SYSSPACE, IO_NOCACHE | IO_NODELOCKED | IO_UNIT, cred, (int *) 0, core_proc);
580 kmem_free(kernel_map, header, header_size);
581
582 if ((coredump_flags & COREDUMP_FULLFSYNC) && error == 0) {
583 error = VNOP_IOCTL(vp, F_FULLFSYNC, (caddr_t)NULL, 0, ctx);
584 }
585 out:
586 error1 = vnode_close(vp, FWRITE, ctx);
587 out2:
588 #if CONFIG_AUDIT
589 audit_proc_coredump(core_proc, name, error);
590 #endif
591 if (alloced_name != NULL) {
592 zfree(ZV_NAMEI, alloced_name);
593 }
594 if (error == 0) {
595 error = error1;
596 }
597
598 return error;
599 }
600
601 #else /* CONFIG_COREDUMP */
602
603 /* When core dumps aren't needed, no need to compile this file at all */
604
605 #error assertion failed: this section is not compiled
606
607 #endif /* CONFIG_COREDUMP */
608