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