1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * fs/proc/kcore.c kernel ELF core dumper
4 *
5 * Modelled on fs/exec.c:aout_core_dump()
6 * Jeremy Fitzhardinge <jeremy@sw.oz.au>
7 * ELF version written by David Howells <David.Howells@nexor.co.uk>
8 * Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
9 * Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
10 * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
11 */
12
13 #include <linux/crash_core.h>
14 #include <linux/mm.h>
15 #include <linux/proc_fs.h>
16 #include <linux/kcore.h>
17 #include <linux/user.h>
18 #include <linux/capability.h>
19 #include <linux/elf.h>
20 #include <linux/elfcore.h>
21 #include <linux/notifier.h>
22 #include <linux/vmalloc.h>
23 #include <linux/highmem.h>
24 #include <linux/printk.h>
25 #include <linux/memblock.h>
26 #include <linux/init.h>
27 #include <linux/slab.h>
28 #include <linux/uaccess.h>
29 #include <asm/io.h>
30 #include <linux/list.h>
31 #include <linux/ioport.h>
32 #include <linux/memory.h>
33 #include <linux/sched/task.h>
34 #include <linux/security.h>
35 #include <asm/sections.h>
36 #include "internal.h"
37
38 #define CORE_STR "CORE"
39
40 #ifndef ELF_CORE_EFLAGS
41 #define ELF_CORE_EFLAGS 0
42 #endif
43
44 static struct proc_dir_entry *proc_root_kcore;
45
46
47 #ifndef kc_vaddr_to_offset
48 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
49 #endif
50 #ifndef kc_offset_to_vaddr
51 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
52 #endif
53
54 static LIST_HEAD(kclist_head);
55 static DECLARE_RWSEM(kclist_lock);
56 static int kcore_need_update = 1;
57
58 /*
59 * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
60 * Same as oldmem_pfn_is_ram in vmcore
61 */
62 static int (*mem_pfn_is_ram)(unsigned long pfn);
63
register_mem_pfn_is_ram(int (* fn)(unsigned long pfn))64 int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn))
65 {
66 if (mem_pfn_is_ram)
67 return -EBUSY;
68 mem_pfn_is_ram = fn;
69 return 0;
70 }
71
pfn_is_ram(unsigned long pfn)72 static int pfn_is_ram(unsigned long pfn)
73 {
74 if (mem_pfn_is_ram)
75 return mem_pfn_is_ram(pfn);
76 else
77 return 1;
78 }
79
80 /* This doesn't grab kclist_lock, so it should only be used at init time. */
kclist_add(struct kcore_list * new,void * addr,size_t size,int type)81 void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
82 int type)
83 {
84 new->addr = (unsigned long)addr;
85 new->size = size;
86 new->type = type;
87
88 list_add_tail(&new->list, &kclist_head);
89 }
90
get_kcore_size(int * nphdr,size_t * phdrs_len,size_t * notes_len,size_t * data_offset)91 static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
92 size_t *data_offset)
93 {
94 size_t try, size;
95 struct kcore_list *m;
96
97 *nphdr = 1; /* PT_NOTE */
98 size = 0;
99
100 list_for_each_entry(m, &kclist_head, list) {
101 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
102 if (try > size)
103 size = try;
104 *nphdr = *nphdr + 1;
105 }
106
107 *phdrs_len = *nphdr * sizeof(struct elf_phdr);
108 *notes_len = (4 * sizeof(struct elf_note) +
109 3 * ALIGN(sizeof(CORE_STR), 4) +
110 VMCOREINFO_NOTE_NAME_BYTES +
111 ALIGN(sizeof(struct elf_prstatus), 4) +
112 ALIGN(sizeof(struct elf_prpsinfo), 4) +
113 ALIGN(arch_task_struct_size, 4) +
114 ALIGN(vmcoreinfo_size, 4));
115 *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
116 *notes_len);
117 return *data_offset + size;
118 }
119
120 #ifdef CONFIG_HIGHMEM
121 /*
122 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
123 * because memory hole is not as big as !HIGHMEM case.
124 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
125 */
kcore_ram_list(struct list_head * head)126 static int kcore_ram_list(struct list_head *head)
127 {
128 struct kcore_list *ent;
129
130 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
131 if (!ent)
132 return -ENOMEM;
133 ent->addr = (unsigned long)__va(0);
134 ent->size = max_low_pfn << PAGE_SHIFT;
135 ent->type = KCORE_RAM;
136 list_add(&ent->list, head);
137 return 0;
138 }
139
140 #else /* !CONFIG_HIGHMEM */
141
142 #ifdef CONFIG_SPARSEMEM_VMEMMAP
143 /* calculate vmemmap's address from given system ram pfn and register it */
144 static int
get_sparsemem_vmemmap_info(struct kcore_list * ent,struct list_head * head)145 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
146 {
147 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
148 unsigned long nr_pages = ent->size >> PAGE_SHIFT;
149 unsigned long start, end;
150 struct kcore_list *vmm, *tmp;
151
152
153 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
154 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
155 end = PAGE_ALIGN(end);
156 /* overlap check (because we have to align page */
157 list_for_each_entry(tmp, head, list) {
158 if (tmp->type != KCORE_VMEMMAP)
159 continue;
160 if (start < tmp->addr + tmp->size)
161 if (end > tmp->addr)
162 end = tmp->addr;
163 }
164 if (start < end) {
165 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
166 if (!vmm)
167 return 0;
168 vmm->addr = start;
169 vmm->size = end - start;
170 vmm->type = KCORE_VMEMMAP;
171 list_add_tail(&vmm->list, head);
172 }
173 return 1;
174
175 }
176 #else
177 static int
get_sparsemem_vmemmap_info(struct kcore_list * ent,struct list_head * head)178 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
179 {
180 return 1;
181 }
182
183 #endif
184
185 static int
kclist_add_private(unsigned long pfn,unsigned long nr_pages,void * arg)186 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
187 {
188 struct list_head *head = (struct list_head *)arg;
189 struct kcore_list *ent;
190 struct page *p;
191
192 if (!pfn_valid(pfn))
193 return 1;
194
195 p = pfn_to_page(pfn);
196 if (!memmap_valid_within(pfn, p, page_zone(p)))
197 return 1;
198
199 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
200 if (!ent)
201 return -ENOMEM;
202 ent->addr = (unsigned long)page_to_virt(p);
203 ent->size = nr_pages << PAGE_SHIFT;
204
205 if (!virt_addr_valid(ent->addr))
206 goto free_out;
207
208 /* cut not-mapped area. ....from ppc-32 code. */
209 if (ULONG_MAX - ent->addr < ent->size)
210 ent->size = ULONG_MAX - ent->addr;
211
212 /*
213 * We've already checked virt_addr_valid so we know this address
214 * is a valid pointer, therefore we can check against it to determine
215 * if we need to trim
216 */
217 if (VMALLOC_START > ent->addr) {
218 if (VMALLOC_START - ent->addr < ent->size)
219 ent->size = VMALLOC_START - ent->addr;
220 }
221
222 ent->type = KCORE_RAM;
223 list_add_tail(&ent->list, head);
224
225 if (!get_sparsemem_vmemmap_info(ent, head)) {
226 list_del(&ent->list);
227 goto free_out;
228 }
229
230 return 0;
231 free_out:
232 kfree(ent);
233 return 1;
234 }
235
kcore_ram_list(struct list_head * list)236 static int kcore_ram_list(struct list_head *list)
237 {
238 int nid, ret;
239 unsigned long end_pfn;
240
241 /* Not inialized....update now */
242 /* find out "max pfn" */
243 end_pfn = 0;
244 for_each_node_state(nid, N_MEMORY) {
245 unsigned long node_end;
246 node_end = node_end_pfn(nid);
247 if (end_pfn < node_end)
248 end_pfn = node_end;
249 }
250 /* scan 0 to max_pfn */
251 ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
252 if (ret)
253 return -ENOMEM;
254 return 0;
255 }
256 #endif /* CONFIG_HIGHMEM */
257
kcore_update_ram(void)258 static int kcore_update_ram(void)
259 {
260 LIST_HEAD(list);
261 LIST_HEAD(garbage);
262 int nphdr;
263 size_t phdrs_len, notes_len, data_offset;
264 struct kcore_list *tmp, *pos;
265 int ret = 0;
266
267 down_write(&kclist_lock);
268 if (!xchg(&kcore_need_update, 0))
269 goto out;
270
271 ret = kcore_ram_list(&list);
272 if (ret) {
273 /* Couldn't get the RAM list, try again next time. */
274 WRITE_ONCE(kcore_need_update, 1);
275 list_splice_tail(&list, &garbage);
276 goto out;
277 }
278
279 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
280 if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
281 list_move(&pos->list, &garbage);
282 }
283 list_splice_tail(&list, &kclist_head);
284
285 proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, ¬es_len,
286 &data_offset);
287
288 out:
289 up_write(&kclist_lock);
290 list_for_each_entry_safe(pos, tmp, &garbage, list) {
291 list_del(&pos->list);
292 kfree(pos);
293 }
294 return ret;
295 }
296
append_kcore_note(char * notes,size_t * i,const char * name,unsigned int type,const void * desc,size_t descsz)297 static void append_kcore_note(char *notes, size_t *i, const char *name,
298 unsigned int type, const void *desc,
299 size_t descsz)
300 {
301 struct elf_note *note = (struct elf_note *)¬es[*i];
302
303 note->n_namesz = strlen(name) + 1;
304 note->n_descsz = descsz;
305 note->n_type = type;
306 *i += sizeof(*note);
307 memcpy(¬es[*i], name, note->n_namesz);
308 *i = ALIGN(*i + note->n_namesz, 4);
309 memcpy(¬es[*i], desc, descsz);
310 *i = ALIGN(*i + descsz, 4);
311 }
312
313 static ssize_t
read_kcore(struct file * file,char __user * buffer,size_t buflen,loff_t * fpos)314 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
315 {
316 char *buf = file->private_data;
317 size_t phdrs_offset, notes_offset, data_offset;
318 size_t phdrs_len, notes_len;
319 struct kcore_list *m;
320 size_t tsz;
321 int nphdr;
322 unsigned long start;
323 size_t orig_buflen = buflen;
324 int ret = 0;
325
326 down_read(&kclist_lock);
327
328 get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset);
329 phdrs_offset = sizeof(struct elfhdr);
330 notes_offset = phdrs_offset + phdrs_len;
331
332 /* ELF file header. */
333 if (buflen && *fpos < sizeof(struct elfhdr)) {
334 struct elfhdr ehdr = {
335 .e_ident = {
336 [EI_MAG0] = ELFMAG0,
337 [EI_MAG1] = ELFMAG1,
338 [EI_MAG2] = ELFMAG2,
339 [EI_MAG3] = ELFMAG3,
340 [EI_CLASS] = ELF_CLASS,
341 [EI_DATA] = ELF_DATA,
342 [EI_VERSION] = EV_CURRENT,
343 [EI_OSABI] = ELF_OSABI,
344 },
345 .e_type = ET_CORE,
346 .e_machine = ELF_ARCH,
347 .e_version = EV_CURRENT,
348 .e_phoff = sizeof(struct elfhdr),
349 .e_flags = ELF_CORE_EFLAGS,
350 .e_ehsize = sizeof(struct elfhdr),
351 .e_phentsize = sizeof(struct elf_phdr),
352 .e_phnum = nphdr,
353 };
354
355 tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
356 if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) {
357 ret = -EFAULT;
358 goto out;
359 }
360
361 buffer += tsz;
362 buflen -= tsz;
363 *fpos += tsz;
364 }
365
366 /* ELF program headers. */
367 if (buflen && *fpos < phdrs_offset + phdrs_len) {
368 struct elf_phdr *phdrs, *phdr;
369
370 phdrs = kzalloc(phdrs_len, GFP_KERNEL);
371 if (!phdrs) {
372 ret = -ENOMEM;
373 goto out;
374 }
375
376 phdrs[0].p_type = PT_NOTE;
377 phdrs[0].p_offset = notes_offset;
378 phdrs[0].p_filesz = notes_len;
379
380 phdr = &phdrs[1];
381 list_for_each_entry(m, &kclist_head, list) {
382 phdr->p_type = PT_LOAD;
383 phdr->p_flags = PF_R | PF_W | PF_X;
384 phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
385 if (m->type == KCORE_REMAP)
386 phdr->p_vaddr = (size_t)m->vaddr;
387 else
388 phdr->p_vaddr = (size_t)m->addr;
389 if (m->type == KCORE_RAM || m->type == KCORE_REMAP)
390 phdr->p_paddr = __pa(m->addr);
391 else if (m->type == KCORE_TEXT)
392 phdr->p_paddr = __pa_symbol(m->addr);
393 else
394 phdr->p_paddr = (elf_addr_t)-1;
395 phdr->p_filesz = phdr->p_memsz = m->size;
396 phdr->p_align = PAGE_SIZE;
397 phdr++;
398 }
399
400 tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
401 if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset,
402 tsz)) {
403 kfree(phdrs);
404 ret = -EFAULT;
405 goto out;
406 }
407 kfree(phdrs);
408
409 buffer += tsz;
410 buflen -= tsz;
411 *fpos += tsz;
412 }
413
414 /* ELF note segment. */
415 if (buflen && *fpos < notes_offset + notes_len) {
416 struct elf_prstatus prstatus = {};
417 struct elf_prpsinfo prpsinfo = {
418 .pr_sname = 'R',
419 .pr_fname = "vmlinux",
420 };
421 char *notes;
422 size_t i = 0;
423
424 strlcpy(prpsinfo.pr_psargs, saved_command_line,
425 sizeof(prpsinfo.pr_psargs));
426
427 notes = kzalloc(notes_len, GFP_KERNEL);
428 if (!notes) {
429 ret = -ENOMEM;
430 goto out;
431 }
432
433 append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
434 sizeof(prstatus));
435 append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
436 sizeof(prpsinfo));
437 append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
438 arch_task_struct_size);
439 /*
440 * vmcoreinfo_size is mostly constant after init time, but it
441 * can be changed by crash_save_vmcoreinfo(). Racing here with a
442 * panic on another CPU before the machine goes down is insanely
443 * unlikely, but it's better to not leave potential buffer
444 * overflows lying around, regardless.
445 */
446 append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
447 vmcoreinfo_data,
448 min(vmcoreinfo_size, notes_len - i));
449
450 tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
451 if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
452 kfree(notes);
453 ret = -EFAULT;
454 goto out;
455 }
456 kfree(notes);
457
458 buffer += tsz;
459 buflen -= tsz;
460 *fpos += tsz;
461 }
462
463 /*
464 * Check to see if our file offset matches with any of
465 * the addresses in the elf_phdr on our list.
466 */
467 start = kc_offset_to_vaddr(*fpos - data_offset);
468 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
469 tsz = buflen;
470
471 m = NULL;
472 while (buflen) {
473 /*
474 * If this is the first iteration or the address is not within
475 * the previous entry, search for a matching entry.
476 */
477 if (!m || start < m->addr || start >= m->addr + m->size) {
478 list_for_each_entry(m, &kclist_head, list) {
479 if (start >= m->addr &&
480 start < m->addr + m->size)
481 break;
482 }
483 }
484
485 if (&m->list == &kclist_head) {
486 if (clear_user(buffer, tsz)) {
487 ret = -EFAULT;
488 goto out;
489 }
490 m = NULL; /* skip the list anchor */
491 } else if (!pfn_is_ram(__pa(start) >> PAGE_SHIFT)) {
492 if (clear_user(buffer, tsz)) {
493 ret = -EFAULT;
494 goto out;
495 }
496 } else if (m->type == KCORE_VMALLOC) {
497 vread(buf, (char *)start, tsz);
498 /* we have to zero-fill user buffer even if no read */
499 if (copy_to_user(buffer, buf, tsz)) {
500 ret = -EFAULT;
501 goto out;
502 }
503 } else if (m->type == KCORE_USER) {
504 /* User page is handled prior to normal kernel page: */
505 if (copy_to_user(buffer, (char *)start, tsz)) {
506 ret = -EFAULT;
507 goto out;
508 }
509 } else {
510 if (kern_addr_valid(start)) {
511 /*
512 * Using bounce buffer to bypass the
513 * hardened user copy kernel text checks.
514 */
515 if (probe_kernel_read(buf, (void *) start, tsz)) {
516 if (clear_user(buffer, tsz)) {
517 ret = -EFAULT;
518 goto out;
519 }
520 } else {
521 if (copy_to_user(buffer, buf, tsz)) {
522 ret = -EFAULT;
523 goto out;
524 }
525 }
526 } else {
527 if (clear_user(buffer, tsz)) {
528 ret = -EFAULT;
529 goto out;
530 }
531 }
532 }
533 buflen -= tsz;
534 *fpos += tsz;
535 buffer += tsz;
536 start += tsz;
537 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
538 }
539
540 out:
541 up_read(&kclist_lock);
542 if (ret)
543 return ret;
544 return orig_buflen - buflen;
545 }
546
open_kcore(struct inode * inode,struct file * filp)547 static int open_kcore(struct inode *inode, struct file *filp)
548 {
549 int ret = security_locked_down(LOCKDOWN_KCORE);
550
551 if (!capable(CAP_SYS_RAWIO))
552 return -EPERM;
553
554 if (ret)
555 return ret;
556
557 filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
558 if (!filp->private_data)
559 return -ENOMEM;
560
561 if (kcore_need_update)
562 kcore_update_ram();
563 if (i_size_read(inode) != proc_root_kcore->size) {
564 inode_lock(inode);
565 i_size_write(inode, proc_root_kcore->size);
566 inode_unlock(inode);
567 }
568 return 0;
569 }
570
release_kcore(struct inode * inode,struct file * file)571 static int release_kcore(struct inode *inode, struct file *file)
572 {
573 kfree(file->private_data);
574 return 0;
575 }
576
577 static const struct file_operations proc_kcore_operations = {
578 .read = read_kcore,
579 .open = open_kcore,
580 .release = release_kcore,
581 .llseek = default_llseek,
582 };
583
584 /* just remember that we have to update kcore */
kcore_callback(struct notifier_block * self,unsigned long action,void * arg)585 static int __meminit kcore_callback(struct notifier_block *self,
586 unsigned long action, void *arg)
587 {
588 switch (action) {
589 case MEM_ONLINE:
590 case MEM_OFFLINE:
591 kcore_need_update = 1;
592 break;
593 }
594 return NOTIFY_OK;
595 }
596
597 static struct notifier_block kcore_callback_nb __meminitdata = {
598 .notifier_call = kcore_callback,
599 .priority = 0,
600 };
601
602 static struct kcore_list kcore_vmalloc;
603
604 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
605 static struct kcore_list kcore_text;
606 /*
607 * If defined, special segment is used for mapping kernel text instead of
608 * direct-map area. We need to create special TEXT section.
609 */
proc_kcore_text_init(void)610 static void __init proc_kcore_text_init(void)
611 {
612 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
613 }
614 #else
proc_kcore_text_init(void)615 static void __init proc_kcore_text_init(void)
616 {
617 }
618 #endif
619
620 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
621 /*
622 * MODULES_VADDR has no intersection with VMALLOC_ADDR.
623 */
624 static struct kcore_list kcore_modules;
add_modules_range(void)625 static void __init add_modules_range(void)
626 {
627 if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
628 kclist_add(&kcore_modules, (void *)MODULES_VADDR,
629 MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
630 }
631 }
632 #else
add_modules_range(void)633 static void __init add_modules_range(void)
634 {
635 }
636 #endif
637
proc_kcore_init(void)638 static int __init proc_kcore_init(void)
639 {
640 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
641 &proc_kcore_operations);
642 if (!proc_root_kcore) {
643 pr_err("couldn't create /proc/kcore\n");
644 return 0; /* Always returns 0. */
645 }
646 /* Store text area if it's special */
647 proc_kcore_text_init();
648 /* Store vmalloc area */
649 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
650 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
651 add_modules_range();
652 /* Store direct-map area from physical memory map */
653 kcore_update_ram();
654 register_hotmemory_notifier(&kcore_callback_nb);
655
656 return 0;
657 }
658 fs_initcall(proc_kcore_init);
659