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