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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/init.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/io.h>
  23 #include <linux/list.h>
  24 #include <asm/sections.h>
  25
  26 #define CORE_STR "CORE"
  27
  28 #ifndef ELF_CORE_EFLAGS
  29 #define ELF_CORE_EFLAGS 0
  30 #endif
  31
  32 static struct proc_dir_entry *proc_root_kcore;
  33
  34 static int open_kcore(struct inode * inode, struct file * filp)
  35 {
  36         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  37 }
  38
  39 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
  40
  41 static const struct file_operations proc_kcore_operations = {
  42         .read           = read_kcore,
  43         .open           = open_kcore,
  44 };
  45
  46 #ifndef kc_vaddr_to_offset
  47 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  48 #endif
  49 #ifndef kc_offset_to_vaddr
  50 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  51 #endif
  52
  53 /* An ELF note in memory */
  54 struct memelfnote
  55 {
  56         const char *name;
  57         int type;
  58         unsigned int datasz;
  59         void *data;
  60 };
  61
  62 static LIST_HEAD(kclist_head);
  63 static DEFINE_RWLOCK(kclist_lock);
  64
  65 void
  66 kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
  67 {
  68         new->addr = (unsigned long)addr;
  69         new->size = size;
  70         new->type = type;
  71
  72         write_lock(&kclist_lock);
  73         list_add_tail(&new->list, &kclist_head);
  74         write_unlock(&kclist_lock);
  75 }
  76
  77 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
  78 {
  79         size_t try, size;
  80         struct kcore_list *m;
  81
  82         *nphdr = 1; /* PT_NOTE */
  83         size = 0;
  84
  85         list_for_each_entry(m, &kclist_head, list) {
  86                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
  87                 if (try > size)
  88                         size = try;
  89                 *nphdr = *nphdr + 1;
  90         }
  91         *elf_buflen =   sizeof(struct elfhdr) +
  92                         (*nphdr + 2)*sizeof(struct elf_phdr) +
  93                         3 * ((sizeof(struct elf_note)) +
  94                              roundup(sizeof(CORE_STR), 4)) +
  95                         roundup(sizeof(struct elf_prstatus), 4) +
  96                         roundup(sizeof(struct elf_prpsinfo), 4) +
  97                         roundup(sizeof(struct task_struct), 4);
  98         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  99         return size + *elf_buflen;
 100 }
 101
 102
 103 /*****************************************************************************/
 104 /*
 105  * determine size of ELF note
 106  */
 107 static int notesize(struct memelfnote *en)
 108 {
 109         int sz;
 110
 111         sz = sizeof(struct elf_note);
 112         sz += roundup((strlen(en->name) + 1), 4);
 113         sz += roundup(en->datasz, 4);
 114
 115         return sz;
 116 } /* end notesize() */
 117
 118 /*****************************************************************************/
 119 /*
 120  * store a note in the header buffer
 121  */
 122 static char *storenote(struct memelfnote *men, char *bufp)
 123 {
 124         struct elf_note en;
 125
 126 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 127
 128         en.n_namesz = strlen(men->name) + 1;
 129         en.n_descsz = men->datasz;
 130         en.n_type = men->type;
 131
 132         DUMP_WRITE(&en, sizeof(en));
 133         DUMP_WRITE(men->name, en.n_namesz);
 134
 135         /* XXX - cast from long long to long to avoid need for libgcc.a */
 136         bufp = (char*) roundup((unsigned long)bufp,4);
 137         DUMP_WRITE(men->data, men->datasz);
 138         bufp = (char*) roundup((unsigned long)bufp,4);
 139
 140 #undef DUMP_WRITE
 141
 142         return bufp;
 143 } /* end storenote() */
 144
 145 /*
 146  * store an ELF coredump header in the supplied buffer
 147  * nphdr is the number of elf_phdr to insert
 148  */
 149 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 150 {
 151         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 152         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 153         struct elf_phdr *nhdr, *phdr;
 154         struct elfhdr *elf;
 155         struct memelfnote notes[3];
 156         off_t offset = 0;
 157         struct kcore_list *m;
 158
 159         /* setup ELF header */
 160         elf = (struct elfhdr *) bufp;
 161         bufp += sizeof(struct elfhdr);
 162         offset += sizeof(struct elfhdr);
 163         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 164         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 165         elf->e_ident[EI_DATA]   = ELF_DATA;
 166         elf->e_ident[EI_VERSION]= EV_CURRENT;
 167         elf->e_ident[EI_OSABI] = ELF_OSABI;
 168         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 169         elf->e_type     = ET_CORE;
 170         elf->e_machine  = ELF_ARCH;
 171         elf->e_version  = EV_CURRENT;
 172         elf->e_entry    = 0;
 173         elf->e_phoff    = sizeof(struct elfhdr);
 174         elf->e_shoff    = 0;
 175         elf->e_flags    = ELF_CORE_EFLAGS;
 176         elf->e_ehsize   = sizeof(struct elfhdr);
 177         elf->e_phentsize= sizeof(struct elf_phdr);
 178         elf->e_phnum    = nphdr;
 179         elf->e_shentsize= 0;
 180         elf->e_shnum    = 0;
 181         elf->e_shstrndx = 0;
 182
 183         /* setup ELF PT_NOTE program header */
 184         nhdr = (struct elf_phdr *) bufp;
 185         bufp += sizeof(struct elf_phdr);
 186         offset += sizeof(struct elf_phdr);
 187         nhdr->p_type    = PT_NOTE;
 188         nhdr->p_offset  = 0;
 189         nhdr->p_vaddr   = 0;
 190         nhdr->p_paddr   = 0;
 191         nhdr->p_filesz  = 0;
 192         nhdr->p_memsz   = 0;
 193         nhdr->p_flags   = 0;
 194         nhdr->p_align   = 0;
 195
 196         /* setup ELF PT_LOAD program header for every area */
 197         list_for_each_entry(m, &kclist_head, list) {
 198                 phdr = (struct elf_phdr *) bufp;
 199                 bufp += sizeof(struct elf_phdr);
 200                 offset += sizeof(struct elf_phdr);
 201
 202                 phdr->p_type    = PT_LOAD;
 203                 phdr->p_flags   = PF_R|PF_W|PF_X;
 204                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 205                 phdr->p_vaddr   = (size_t)m->addr;
 206                 phdr->p_paddr   = 0;
 207                 phdr->p_filesz  = phdr->p_memsz = m->size;
 208                 phdr->p_align   = PAGE_SIZE;
 209         }
 210
 211         /*
 212          * Set up the notes in similar form to SVR4 core dumps made
 213          * with info from their /proc.
 214          */
 215         nhdr->p_offset  = offset;
 216
 217         /* set up the process status */
 218         notes[0].name = CORE_STR;
 219         notes[0].type = NT_PRSTATUS;
 220         notes[0].datasz = sizeof(struct elf_prstatus);
 221         notes[0].data = &prstatus;
 222
 223         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 224
 225         nhdr->p_filesz  = notesize(&notes[0]);
 226         bufp = storenote(&notes[0], bufp);
 227
 228         /* set up the process info */
 229         notes[1].name   = CORE_STR;
 230         notes[1].type   = NT_PRPSINFO;
 231         notes[1].datasz = sizeof(struct elf_prpsinfo);
 232         notes[1].data   = &prpsinfo;
 233
 234         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 235         prpsinfo.pr_state       = 0;
 236         prpsinfo.pr_sname       = 'R';
 237         prpsinfo.pr_zomb        = 0;
 238
 239         strcpy(prpsinfo.pr_fname, "vmlinux");
 240         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 241
 242         nhdr->p_filesz  += notesize(&notes[1]);
 243         bufp = storenote(&notes[1], bufp);
 244
 245         /* set up the task structure */
 246         notes[2].name   = CORE_STR;
 247         notes[2].type   = NT_TASKSTRUCT;
 248         notes[2].datasz = sizeof(struct task_struct);
 249         notes[2].data   = current;
 250
 251         nhdr->p_filesz  += notesize(&notes[2]);
 252         bufp = storenote(&notes[2], bufp);
 253
 254 } /* end elf_kcore_store_hdr() */
 255
 256 /*****************************************************************************/
 257 /*
 258  * read from the ELF header and then kernel memory
 259  */
 260 static ssize_t
 261 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 262 {
 263         ssize_t acc = 0;
 264         size_t size, tsz;
 265         size_t elf_buflen;
 266         int nphdr;
 267         unsigned long start;
 268
 269         read_lock(&kclist_lock);
 270         proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
 271         if (buflen == 0 || *fpos >= size) {
 272                 read_unlock(&kclist_lock);
 273                 return 0;
 274         }
 275
 276         /* trim buflen to not go beyond EOF */
 277         if (buflen > size - *fpos)
 278                 buflen = size - *fpos;
 279
 280         /* construct an ELF core header if we'll need some of it */
 281         if (*fpos < elf_buflen) {
 282                 char * elf_buf;
 283
 284                 tsz = elf_buflen - *fpos;
 285                 if (buflen < tsz)
 286                         tsz = buflen;
 287                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
 288                 if (!elf_buf) {
 289                         read_unlock(&kclist_lock);
 290                         return -ENOMEM;
 291                 }
 292                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 293                 read_unlock(&kclist_lock);
 294                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 295                         kfree(elf_buf);
 296                         return -EFAULT;
 297                 }
 298                 kfree(elf_buf);
 299                 buflen -= tsz;
 300                 *fpos += tsz;
 301                 buffer += tsz;
 302                 acc += tsz;
 303
 304                 /* leave now if filled buffer already */
 305                 if (buflen == 0)
 306                         return acc;
 307         } else
 308                 read_unlock(&kclist_lock);
 309
 310         /*
 311          * Check to see if our file offset matches with any of
 312          * the addresses in the elf_phdr on our list.
 313          */
 314         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 315         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 316                 tsz = buflen;
 317
 318         while (buflen) {
 319                 struct kcore_list *m;
 320
 321                 read_lock(&kclist_lock);
 322                 list_for_each_entry(m, &kclist_head, list) {
 323                         if (start >= m->addr && start < (m->addr+m->size))
 324                                 break;
 325                 }
 326                 read_unlock(&kclist_lock);
 327
 328                 if (m == NULL) {
 329                         if (clear_user(buffer, tsz))
 330                                 return -EFAULT;
 331                 } else if (is_vmalloc_addr((void *)start)) {
 332                         char * elf_buf;
 333
 334                         elf_buf = kzalloc(tsz, GFP_KERNEL);
 335                         if (!elf_buf)
 336                                 return -ENOMEM;
 337                         vread(elf_buf, (char *)start, tsz);
 338                         /* we have to zero-fill user buffer even if no read */
 339                         if (copy_to_user(buffer, elf_buf, tsz)) {
 340                                 kfree(elf_buf);
 341                                 return -EFAULT;
 342                         }
 343                         kfree(elf_buf);
 344                 } else {
 345                         if (kern_addr_valid(start)) {
 346                                 unsigned long n;
 347
 348                                 n = copy_to_user(buffer, (char *)start, tsz);
 349                                 /*
 350                                  * We cannot distingush between fault on source
 351                                  * and fault on destination. When this happens
 352                                  * we clear too and hope it will trigger the
 353                                  * EFAULT again.
 354                                  */
 355                                 if (n) {
 356                                         if (clear_user(buffer + tsz - n,
 357                                                                 n))
 358                                                 return -EFAULT;
 359                                 }
 360                         } else {
 361                                 if (clear_user(buffer, tsz))
 362                                         return -EFAULT;
 363                         }
 364                 }
 365                 buflen -= tsz;
 366                 *fpos += tsz;
 367                 buffer += tsz;
 368                 acc += tsz;
 369                 start += tsz;
 370                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 371         }
 372
 373         return acc;
 374 }
 375
 376 static struct kcore_list kcore_vmalloc;
 377
 378 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
 379 static struct kcore_list kcore_text;
 380 /*
 381  * If defined, special segment is used for mapping kernel text instead of
 382  * direct-map area. We need to create special TEXT section.
 383  */
 384 static void __init proc_kcore_text_init(void)
 385 {
 386         kclist_add(&kcore_text, _stext, _end - _stext, KCORE_TEXT);
 387 }
 388 #else
 389 static void __init proc_kcore_text_init(void)
 390 {
 391 }
 392 #endif
 393
 394 static int __init proc_kcore_init(void)
 395 {
 396         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations);
 397         proc_kcore_text_init();
 398         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 399                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 400         return 0;
 401 }
 402 module_init(proc_kcore_init);