fs/proc/kcore.c

   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 = ALIGN(end, PAGE_SIZE);
 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(&notes[0]);
 396         bufp = storenote(&notes[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(&notes[1]);
 413         bufp = storenote(&notes[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(&notes[2]);
 422         bufp = storenote(&notes[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         kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 614                         MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
 615 }
 616 #else
 617 static void __init add_modules_range(void)
 618 {
 619 }
 620 #endif
 621
 622 static int __init proc_kcore_init(void)
 623 {
 624         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
 625                                       &proc_kcore_operations);
 626         if (!proc_root_kcore) {
 627                 pr_err("couldn't create /proc/kcore\n");
 628                 return 0; /* Always returns 0. */
 629         }
 630         /* Store text area if it's special */
 631         proc_kcore_text_init();
 632         /* Store vmalloc area */
 633         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 634                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 635         add_modules_range();
 636         /* Store direct-map area from physical memory map */
 637         kcore_update_ram();
 638         register_hotmemory_notifier(&kcore_callback_nb);
 639
 640         return 0;
 641 }
 642 fs_initcall(proc_kcore_init);