1 /* 2 * fs/proc/kcore.c kernel ELF core dumper 3 * 4 * Modelled on fs/exec.c:aout_core_dump() 5 * Jeremy Fitzhardinge <jeremy@sw.oz.au> 6 * ELF version written by David Howells <David.Howells@nexor.co.uk> 7 * Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com> 8 * Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com> 9 * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com> 10 */ 11 12 #include <linux/mm.h> 13 #include <linux/proc_fs.h> 14 #include <linux/kcore.h> 15 #include <linux/user.h> 16 #include <linux/capability.h> 17 #include <linux/elf.h> 18 #include <linux/elfcore.h> 19 #include <linux/notifier.h> 20 #include <linux/vmalloc.h> 21 #include <linux/highmem.h> 22 #include <linux/printk.h> 23 #include <linux/bootmem.h> 24 #include <linux/init.h> 25 #include <linux/slab.h> 26 #include <asm/uaccess.h> 27 #include <asm/io.h> 28 #include <linux/list.h> 29 #include <linux/ioport.h> 30 #include <linux/memory.h> 31 #include <asm/sections.h> 32 #include "internal.h" 33 34 #define CORE_STR "CORE" 35 36 #ifndef ELF_CORE_EFLAGS 37 #define ELF_CORE_EFLAGS 0 38 #endif 39 40 static struct proc_dir_entry *proc_root_kcore; 41 42 43 #ifndef kc_vaddr_to_offset 44 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET) 45 #endif 46 #ifndef kc_offset_to_vaddr 47 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET) 48 #endif 49 50 /* An ELF note in memory */ 51 struct memelfnote 52 { 53 const char *name; 54 int type; 55 unsigned int datasz; 56 void *data; 57 }; 58 59 static LIST_HEAD(kclist_head); 60 static DEFINE_RWLOCK(kclist_lock); 61 static int kcore_need_update = 1; 62 63 void 64 kclist_add(struct kcore_list *new, void *addr, size_t size, int type) 65 { 66 new->addr = (unsigned long)addr; 67 new->size = size; 68 new->type = type; 69 70 write_lock(&kclist_lock); 71 list_add_tail(&new->list, &kclist_head); 72 write_unlock(&kclist_lock); 73 } 74 75 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) 76 { 77 size_t try, size; 78 struct kcore_list *m; 79 80 *nphdr = 1; /* PT_NOTE */ 81 size = 0; 82 83 list_for_each_entry(m, &kclist_head, list) { 84 try = kc_vaddr_to_offset((size_t)m->addr + m->size); 85 if (try > size) 86 size = try; 87 *nphdr = *nphdr + 1; 88 } 89 *elf_buflen = sizeof(struct elfhdr) + 90 (*nphdr + 2)*sizeof(struct elf_phdr) + 91 3 * ((sizeof(struct elf_note)) + 92 roundup(sizeof(CORE_STR), 4)) + 93 roundup(sizeof(struct elf_prstatus), 4) + 94 roundup(sizeof(struct elf_prpsinfo), 4) + 95 roundup(sizeof(struct task_struct), 4); 96 *elf_buflen = PAGE_ALIGN(*elf_buflen); 97 return size + *elf_buflen; 98 } 99 100 static void free_kclist_ents(struct list_head *head) 101 { 102 struct kcore_list *tmp, *pos; 103 104 list_for_each_entry_safe(pos, tmp, head, list) { 105 list_del(&pos->list); 106 kfree(pos); 107 } 108 } 109 /* 110 * Replace all KCORE_RAM/KCORE_VMEMMAP information with passed list. 111 */ 112 static void __kcore_update_ram(struct list_head *list) 113 { 114 int nphdr; 115 size_t size; 116 struct kcore_list *tmp, *pos; 117 LIST_HEAD(garbage); 118 119 write_lock(&kclist_lock); 120 if (kcore_need_update) { 121 list_for_each_entry_safe(pos, tmp, &kclist_head, list) { 122 if (pos->type == KCORE_RAM 123 || pos->type == KCORE_VMEMMAP) 124 list_move(&pos->list, &garbage); 125 } 126 list_splice_tail(list, &kclist_head); 127 } else 128 list_splice(list, &garbage); 129 kcore_need_update = 0; 130 proc_root_kcore->size = get_kcore_size(&nphdr, &size); 131 write_unlock(&kclist_lock); 132 133 free_kclist_ents(&garbage); 134 } 135 136 137 #ifdef CONFIG_HIGHMEM 138 /* 139 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory 140 * because memory hole is not as big as !HIGHMEM case. 141 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.) 142 */ 143 static int kcore_update_ram(void) 144 { 145 LIST_HEAD(head); 146 struct kcore_list *ent; 147 int ret = 0; 148 149 ent = kmalloc(sizeof(*ent), GFP_KERNEL); 150 if (!ent) 151 return -ENOMEM; 152 ent->addr = (unsigned long)__va(0); 153 ent->size = max_low_pfn << PAGE_SHIFT; 154 ent->type = KCORE_RAM; 155 list_add(&ent->list, &head); 156 __kcore_update_ram(&head); 157 return ret; 158 } 159 160 #else /* !CONFIG_HIGHMEM */ 161 162 #ifdef CONFIG_SPARSEMEM_VMEMMAP 163 /* calculate vmemmap's address from given system ram pfn and register it */ 164 static int 165 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head) 166 { 167 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT; 168 unsigned long nr_pages = ent->size >> PAGE_SHIFT; 169 unsigned long start, end; 170 struct kcore_list *vmm, *tmp; 171 172 173 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK; 174 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1; 175 end = PAGE_ALIGN(end); 176 /* overlap check (because we have to align page */ 177 list_for_each_entry(tmp, head, list) { 178 if (tmp->type != KCORE_VMEMMAP) 179 continue; 180 if (start < tmp->addr + tmp->size) 181 if (end > tmp->addr) 182 end = tmp->addr; 183 } 184 if (start < end) { 185 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL); 186 if (!vmm) 187 return 0; 188 vmm->addr = start; 189 vmm->size = end - start; 190 vmm->type = KCORE_VMEMMAP; 191 list_add_tail(&vmm->list, head); 192 } 193 return 1; 194 195 } 196 #else 197 static int 198 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head) 199 { 200 return 1; 201 } 202 203 #endif 204 205 static int 206 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg) 207 { 208 struct list_head *head = (struct list_head *)arg; 209 struct kcore_list *ent; 210 211 ent = kmalloc(sizeof(*ent), GFP_KERNEL); 212 if (!ent) 213 return -ENOMEM; 214 ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT)); 215 ent->size = nr_pages << PAGE_SHIFT; 216 217 /* Sanity check: Can happen in 32bit arch...maybe */ 218 if (ent->addr < (unsigned long) __va(0)) 219 goto free_out; 220 221 /* cut not-mapped area. ....from ppc-32 code. */ 222 if (ULONG_MAX - ent->addr < ent->size) 223 ent->size = ULONG_MAX - ent->addr; 224 225 /* cut when vmalloc() area is higher than direct-map area */ 226 if (VMALLOC_START > (unsigned long)__va(0)) { 227 if (ent->addr > VMALLOC_START) 228 goto free_out; 229 if (VMALLOC_START - ent->addr < ent->size) 230 ent->size = VMALLOC_START - ent->addr; 231 } 232 233 ent->type = KCORE_RAM; 234 list_add_tail(&ent->list, head); 235 236 if (!get_sparsemem_vmemmap_info(ent, head)) { 237 list_del(&ent->list); 238 goto free_out; 239 } 240 241 return 0; 242 free_out: 243 kfree(ent); 244 return 1; 245 } 246 247 static int kcore_update_ram(void) 248 { 249 int nid, ret; 250 unsigned long end_pfn; 251 LIST_HEAD(head); 252 253 /* Not inialized....update now */ 254 /* find out "max pfn" */ 255 end_pfn = 0; 256 for_each_node_state(nid, N_MEMORY) { 257 unsigned long node_end; 258 node_end = node_end_pfn(nid); 259 if (end_pfn < node_end) 260 end_pfn = node_end; 261 } 262 /* scan 0 to max_pfn */ 263 ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private); 264 if (ret) { 265 free_kclist_ents(&head); 266 return -ENOMEM; 267 } 268 __kcore_update_ram(&head); 269 return ret; 270 } 271 #endif /* CONFIG_HIGHMEM */ 272 273 /*****************************************************************************/ 274 /* 275 * determine size of ELF note 276 */ 277 static int notesize(struct memelfnote *en) 278 { 279 int sz; 280 281 sz = sizeof(struct elf_note); 282 sz += roundup((strlen(en->name) + 1), 4); 283 sz += roundup(en->datasz, 4); 284 285 return sz; 286 } /* end notesize() */ 287 288 /*****************************************************************************/ 289 /* 290 * store a note in the header buffer 291 */ 292 static char *storenote(struct memelfnote *men, char *bufp) 293 { 294 struct elf_note en; 295 296 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0) 297 298 en.n_namesz = strlen(men->name) + 1; 299 en.n_descsz = men->datasz; 300 en.n_type = men->type; 301 302 DUMP_WRITE(&en, sizeof(en)); 303 DUMP_WRITE(men->name, en.n_namesz); 304 305 /* XXX - cast from long long to long to avoid need for libgcc.a */ 306 bufp = (char*) roundup((unsigned long)bufp,4); 307 DUMP_WRITE(men->data, men->datasz); 308 bufp = (char*) roundup((unsigned long)bufp,4); 309 310 #undef DUMP_WRITE 311 312 return bufp; 313 } /* end storenote() */ 314 315 /* 316 * store an ELF coredump header in the supplied buffer 317 * nphdr is the number of elf_phdr to insert 318 */ 319 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) 320 { 321 struct elf_prstatus prstatus; /* NT_PRSTATUS */ 322 struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */ 323 struct elf_phdr *nhdr, *phdr; 324 struct elfhdr *elf; 325 struct memelfnote notes[3]; 326 off_t offset = 0; 327 struct kcore_list *m; 328 329 /* setup ELF header */ 330 elf = (struct elfhdr *) bufp; 331 bufp += sizeof(struct elfhdr); 332 offset += sizeof(struct elfhdr); 333 memcpy(elf->e_ident, ELFMAG, SELFMAG); 334 elf->e_ident[EI_CLASS] = ELF_CLASS; 335 elf->e_ident[EI_DATA] = ELF_DATA; 336 elf->e_ident[EI_VERSION]= EV_CURRENT; 337 elf->e_ident[EI_OSABI] = ELF_OSABI; 338 memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD); 339 elf->e_type = ET_CORE; 340 elf->e_machine = ELF_ARCH; 341 elf->e_version = EV_CURRENT; 342 elf->e_entry = 0; 343 elf->e_phoff = sizeof(struct elfhdr); 344 elf->e_shoff = 0; 345 elf->e_flags = ELF_CORE_EFLAGS; 346 elf->e_ehsize = sizeof(struct elfhdr); 347 elf->e_phentsize= sizeof(struct elf_phdr); 348 elf->e_phnum = nphdr; 349 elf->e_shentsize= 0; 350 elf->e_shnum = 0; 351 elf->e_shstrndx = 0; 352 353 /* setup ELF PT_NOTE program header */ 354 nhdr = (struct elf_phdr *) bufp; 355 bufp += sizeof(struct elf_phdr); 356 offset += sizeof(struct elf_phdr); 357 nhdr->p_type = PT_NOTE; 358 nhdr->p_offset = 0; 359 nhdr->p_vaddr = 0; 360 nhdr->p_paddr = 0; 361 nhdr->p_filesz = 0; 362 nhdr->p_memsz = 0; 363 nhdr->p_flags = 0; 364 nhdr->p_align = 0; 365 366 /* setup ELF PT_LOAD program header for every area */ 367 list_for_each_entry(m, &kclist_head, list) { 368 phdr = (struct elf_phdr *) bufp; 369 bufp += sizeof(struct elf_phdr); 370 offset += sizeof(struct elf_phdr); 371 372 phdr->p_type = PT_LOAD; 373 phdr->p_flags = PF_R|PF_W|PF_X; 374 phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff; 375 phdr->p_vaddr = (size_t)m->addr; 376 phdr->p_paddr = 0; 377 phdr->p_filesz = phdr->p_memsz = m->size; 378 phdr->p_align = PAGE_SIZE; 379 } 380 381 /* 382 * Set up the notes in similar form to SVR4 core dumps made 383 * with info from their /proc. 384 */ 385 nhdr->p_offset = offset; 386 387 /* set up the process status */ 388 notes[0].name = CORE_STR; 389 notes[0].type = NT_PRSTATUS; 390 notes[0].datasz = sizeof(struct elf_prstatus); 391 notes[0].data = &prstatus; 392 393 memset(&prstatus, 0, sizeof(struct elf_prstatus)); 394 395 nhdr->p_filesz = notesize(¬es[0]); 396 bufp = storenote(¬es[0], bufp); 397 398 /* set up the process info */ 399 notes[1].name = CORE_STR; 400 notes[1].type = NT_PRPSINFO; 401 notes[1].datasz = sizeof(struct elf_prpsinfo); 402 notes[1].data = &prpsinfo; 403 404 memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo)); 405 prpsinfo.pr_state = 0; 406 prpsinfo.pr_sname = 'R'; 407 prpsinfo.pr_zomb = 0; 408 409 strcpy(prpsinfo.pr_fname, "vmlinux"); 410 strlcpy(prpsinfo.pr_psargs, saved_command_line, sizeof(prpsinfo.pr_psargs)); 411 412 nhdr->p_filesz += notesize(¬es[1]); 413 bufp = storenote(¬es[1], bufp); 414 415 /* set up the task structure */ 416 notes[2].name = CORE_STR; 417 notes[2].type = NT_TASKSTRUCT; 418 notes[2].datasz = sizeof(struct task_struct); 419 notes[2].data = current; 420 421 nhdr->p_filesz += notesize(¬es[2]); 422 bufp = storenote(¬es[2], bufp); 423 424 } /* end elf_kcore_store_hdr() */ 425 426 /*****************************************************************************/ 427 /* 428 * read from the ELF header and then kernel memory 429 */ 430 static ssize_t 431 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 432 { 433 ssize_t acc = 0; 434 size_t size, tsz; 435 size_t elf_buflen; 436 int nphdr; 437 unsigned long start; 438 439 read_lock(&kclist_lock); 440 size = get_kcore_size(&nphdr, &elf_buflen); 441 442 if (buflen == 0 || *fpos >= size) { 443 read_unlock(&kclist_lock); 444 return 0; 445 } 446 447 /* trim buflen to not go beyond EOF */ 448 if (buflen > size - *fpos) 449 buflen = size - *fpos; 450 451 /* construct an ELF core header if we'll need some of it */ 452 if (*fpos < elf_buflen) { 453 char * elf_buf; 454 455 tsz = elf_buflen - *fpos; 456 if (buflen < tsz) 457 tsz = buflen; 458 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC); 459 if (!elf_buf) { 460 read_unlock(&kclist_lock); 461 return -ENOMEM; 462 } 463 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); 464 read_unlock(&kclist_lock); 465 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { 466 kfree(elf_buf); 467 return -EFAULT; 468 } 469 kfree(elf_buf); 470 buflen -= tsz; 471 *fpos += tsz; 472 buffer += tsz; 473 acc += tsz; 474 475 /* leave now if filled buffer already */ 476 if (buflen == 0) 477 return acc; 478 } else 479 read_unlock(&kclist_lock); 480 481 /* 482 * Check to see if our file offset matches with any of 483 * the addresses in the elf_phdr on our list. 484 */ 485 start = kc_offset_to_vaddr(*fpos - elf_buflen); 486 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) 487 tsz = buflen; 488 489 while (buflen) { 490 struct kcore_list *m; 491 492 read_lock(&kclist_lock); 493 list_for_each_entry(m, &kclist_head, list) { 494 if (start >= m->addr && start < (m->addr+m->size)) 495 break; 496 } 497 read_unlock(&kclist_lock); 498 499 if (&m->list == &kclist_head) { 500 if (clear_user(buffer, tsz)) 501 return -EFAULT; 502 } else if (is_vmalloc_or_module_addr((void *)start)) { 503 char * elf_buf; 504 505 elf_buf = kzalloc(tsz, GFP_KERNEL); 506 if (!elf_buf) 507 return -ENOMEM; 508 vread(elf_buf, (char *)start, tsz); 509 /* we have to zero-fill user buffer even if no read */ 510 if (copy_to_user(buffer, elf_buf, tsz)) { 511 kfree(elf_buf); 512 return -EFAULT; 513 } 514 kfree(elf_buf); 515 } else { 516 if (kern_addr_valid(start)) { 517 unsigned long n; 518 519 n = copy_to_user(buffer, (char *)start, tsz); 520 /* 521 * We cannot distinguish between fault on source 522 * and fault on destination. When this happens 523 * we clear too and hope it will trigger the 524 * EFAULT again. 525 */ 526 if (n) { 527 if (clear_user(buffer + tsz - n, 528 n)) 529 return -EFAULT; 530 } 531 } else { 532 if (clear_user(buffer, tsz)) 533 return -EFAULT; 534 } 535 } 536 buflen -= tsz; 537 *fpos += tsz; 538 buffer += tsz; 539 acc += tsz; 540 start += tsz; 541 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); 542 } 543 544 return acc; 545 } 546 547 548 static int open_kcore(struct inode *inode, struct file *filp) 549 { 550 if (!capable(CAP_SYS_RAWIO)) 551 return -EPERM; 552 if (kcore_need_update) 553 kcore_update_ram(); 554 if (i_size_read(inode) != proc_root_kcore->size) { 555 mutex_lock(&inode->i_mutex); 556 i_size_write(inode, proc_root_kcore->size); 557 mutex_unlock(&inode->i_mutex); 558 } 559 return 0; 560 } 561 562 563 static const struct file_operations proc_kcore_operations = { 564 .read = read_kcore, 565 .open = open_kcore, 566 .llseek = default_llseek, 567 }; 568 569 /* just remember that we have to update kcore */ 570 static int __meminit kcore_callback(struct notifier_block *self, 571 unsigned long action, void *arg) 572 { 573 switch (action) { 574 case MEM_ONLINE: 575 case MEM_OFFLINE: 576 write_lock(&kclist_lock); 577 kcore_need_update = 1; 578 write_unlock(&kclist_lock); 579 } 580 return NOTIFY_OK; 581 } 582 583 static struct notifier_block kcore_callback_nb __meminitdata = { 584 .notifier_call = kcore_callback, 585 .priority = 0, 586 }; 587 588 static struct kcore_list kcore_vmalloc; 589 590 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT 591 static struct kcore_list kcore_text; 592 /* 593 * If defined, special segment is used for mapping kernel text instead of 594 * direct-map area. We need to create special TEXT section. 595 */ 596 static void __init proc_kcore_text_init(void) 597 { 598 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT); 599 } 600 #else 601 static void __init proc_kcore_text_init(void) 602 { 603 } 604 #endif 605 606 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR) 607 /* 608 * MODULES_VADDR has no intersection with VMALLOC_ADDR. 609 */ 610 struct kcore_list kcore_modules; 611 static void __init add_modules_range(void) 612 { 613 if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) { 614 kclist_add(&kcore_modules, (void *)MODULES_VADDR, 615 MODULES_END - MODULES_VADDR, KCORE_VMALLOC); 616 } 617 } 618 #else 619 static void __init add_modules_range(void) 620 { 621 } 622 #endif 623 624 static int __init proc_kcore_init(void) 625 { 626 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, 627 &proc_kcore_operations); 628 if (!proc_root_kcore) { 629 pr_err("couldn't create /proc/kcore\n"); 630 return 0; /* Always returns 0. */ 631 } 632 /* Store text area if it's special */ 633 proc_kcore_text_init(); 634 /* Store vmalloc area */ 635 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, 636 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC); 637 add_modules_range(); 638 /* Store direct-map area from physical memory map */ 639 kcore_update_ram(); 640 register_hotmemory_notifier(&kcore_callback_nb); 641 642 return 0; 643 } 644 fs_initcall(proc_kcore_init); 645