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/config.h>
  13 #include <linux/mm.h>
  14 #include <linux/proc_fs.h>
  15 #include <linux/user.h>
  16 #include <linux/a.out.h>
  17 #include <linux/capability.h>
  18 #include <linux/elf.h>
  19 #include <linux/elfcore.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/highmem.h>
  22 #include <linux/init.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/io.h>
  25
  26
  27 static int open_kcore(struct inode * inode, struct file * filp)
  28 {
  29         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  30 }
  31
  32 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
  33
  34 struct file_operations proc_kcore_operations = {
  35         .read           = read_kcore,
  36         .open           = open_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 #define roundup(x, y)  ((((x)+((y)-1))/(y))*(y))
  47
  48 /* An ELF note in memory */
  49 struct memelfnote
  50 {
  51         const char *name;
  52         int type;
  53         unsigned int datasz;
  54         void *data;
  55 };
  56
  57 static struct kcore_list *kclist;
  58 static DEFINE_RWLOCK(kclist_lock);
  59
  60 void
  61 kclist_add(struct kcore_list *new, void *addr, size_t size)
  62 {
  63         new->addr = (unsigned long)addr;
  64         new->size = size;
  65
  66         write_lock(&kclist_lock);
  67         new->next = kclist;
  68         kclist = new;
  69         write_unlock(&kclist_lock);
  70 }
  71
  72 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
  73 {
  74         size_t try, size;
  75         struct kcore_list *m;
  76
  77         *nphdr = 1; /* PT_NOTE */
  78         size = 0;
  79
  80         for (m=kclist; m; m=m->next) {
  81                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
  82                 if (try > size)
  83                         size = try;
  84                 *nphdr = *nphdr + 1;
  85         }
  86         *elf_buflen =   sizeof(struct elfhdr) +
  87                         (*nphdr + 2)*sizeof(struct elf_phdr) +
  88                         3 * (sizeof(struct elf_note) + 4) +
  89                         sizeof(struct elf_prstatus) +
  90                         sizeof(struct elf_prpsinfo) +
  91                         sizeof(struct task_struct);
  92         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  93         return size + *elf_buflen;
  94 }
  95
  96
  97 /*****************************************************************************/
  98 /*
  99  * determine size of ELF note
 100  */
 101 static int notesize(struct memelfnote *en)
 102 {
 103         int sz;
 104
 105         sz = sizeof(struct elf_note);
 106         sz += roundup(strlen(en->name), 4);
 107         sz += roundup(en->datasz, 4);
 108
 109         return sz;
 110 } /* end notesize() */
 111
 112 /*****************************************************************************/
 113 /*
 114  * store a note in the header buffer
 115  */
 116 static char *storenote(struct memelfnote *men, char *bufp)
 117 {
 118         struct elf_note en;
 119
 120 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 121
 122         en.n_namesz = strlen(men->name);
 123         en.n_descsz = men->datasz;
 124         en.n_type = men->type;
 125
 126         DUMP_WRITE(&en, sizeof(en));
 127         DUMP_WRITE(men->name, en.n_namesz);
 128
 129         /* XXX - cast from long long to long to avoid need for libgcc.a */
 130         bufp = (char*) roundup((unsigned long)bufp,4);
 131         DUMP_WRITE(men->data, men->datasz);
 132         bufp = (char*) roundup((unsigned long)bufp,4);
 133
 134 #undef DUMP_WRITE
 135
 136         return bufp;
 137 } /* end storenote() */
 138
 139 /*
 140  * store an ELF coredump header in the supplied buffer
 141  * nphdr is the number of elf_phdr to insert
 142  */
 143 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 144 {
 145         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 146         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 147         struct elf_phdr *nhdr, *phdr;
 148         struct elfhdr *elf;
 149         struct memelfnote notes[3];
 150         off_t offset = 0;
 151         struct kcore_list *m;
 152
 153         /* setup ELF header */
 154         elf = (struct elfhdr *) bufp;
 155         bufp += sizeof(struct elfhdr);
 156         offset += sizeof(struct elfhdr);
 157         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 158         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 159         elf->e_ident[EI_DATA]   = ELF_DATA;
 160         elf->e_ident[EI_VERSION]= EV_CURRENT;
 161         elf->e_ident[EI_OSABI] = ELF_OSABI;
 162         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 163         elf->e_type     = ET_CORE;
 164         elf->e_machine  = ELF_ARCH;
 165         elf->e_version  = EV_CURRENT;
 166         elf->e_entry    = 0;
 167         elf->e_phoff    = sizeof(struct elfhdr);
 168         elf->e_shoff    = 0;
 169 #if defined(CONFIG_H8300)
 170         elf->e_flags    = ELF_FLAGS;
 171 #else
 172         elf->e_flags    = 0;
 173 #endif
 174         elf->e_ehsize   = sizeof(struct elfhdr);
 175         elf->e_phentsize= sizeof(struct elf_phdr);
 176         elf->e_phnum    = nphdr;
 177         elf->e_shentsize= 0;
 178         elf->e_shnum    = 0;
 179         elf->e_shstrndx = 0;
 180
 181         /* setup ELF PT_NOTE program header */
 182         nhdr = (struct elf_phdr *) bufp;
 183         bufp += sizeof(struct elf_phdr);
 184         offset += sizeof(struct elf_phdr);
 185         nhdr->p_type    = PT_NOTE;
 186         nhdr->p_offset  = 0;
 187         nhdr->p_vaddr   = 0;
 188         nhdr->p_paddr   = 0;
 189         nhdr->p_filesz  = 0;
 190         nhdr->p_memsz   = 0;
 191         nhdr->p_flags   = 0;
 192         nhdr->p_align   = 0;
 193
 194         /* setup ELF PT_LOAD program header for every area */
 195         for (m=kclist; m; m=m->next) {
 196                 phdr = (struct elf_phdr *) bufp;
 197                 bufp += sizeof(struct elf_phdr);
 198                 offset += sizeof(struct elf_phdr);
 199
 200                 phdr->p_type    = PT_LOAD;
 201                 phdr->p_flags   = PF_R|PF_W|PF_X;
 202                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 203                 phdr->p_vaddr   = (size_t)m->addr;
 204                 phdr->p_paddr   = 0;
 205                 phdr->p_filesz  = phdr->p_memsz = m->size;
 206                 phdr->p_align   = PAGE_SIZE;
 207         }
 208
 209         /*
 210          * Set up the notes in similar form to SVR4 core dumps made
 211          * with info from their /proc.
 212          */
 213         nhdr->p_offset  = offset;
 214
 215         /* set up the process status */
 216         notes[0].name = "CORE";
 217         notes[0].type = NT_PRSTATUS;
 218         notes[0].datasz = sizeof(struct elf_prstatus);
 219         notes[0].data = &prstatus;
 220
 221         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 222
 223         nhdr->p_filesz  = notesize(&notes[0]);
 224         bufp = storenote(&notes[0], bufp);
 225
 226         /* set up the process info */
 227         notes[1].name   = "CORE";
 228         notes[1].type   = NT_PRPSINFO;
 229         notes[1].datasz = sizeof(struct elf_prpsinfo);
 230         notes[1].data   = &prpsinfo;
 231
 232         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 233         prpsinfo.pr_state       = 0;
 234         prpsinfo.pr_sname       = 'R';
 235         prpsinfo.pr_zomb        = 0;
 236
 237         strcpy(prpsinfo.pr_fname, "vmlinux");
 238         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 239
 240         nhdr->p_filesz  += notesize(&notes[1]);
 241         bufp = storenote(&notes[1], bufp);
 242
 243         /* set up the task structure */
 244         notes[2].name   = "CORE";
 245         notes[2].type   = NT_TASKSTRUCT;
 246         notes[2].datasz = sizeof(struct task_struct);
 247         notes[2].data   = current;
 248
 249         nhdr->p_filesz  += notesize(&notes[2]);
 250         bufp = storenote(&notes[2], bufp);
 251
 252 } /* end elf_kcore_store_hdr() */
 253
 254 /*****************************************************************************/
 255 /*
 256  * read from the ELF header and then kernel memory
 257  */
 258 static ssize_t
 259 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 260 {
 261         ssize_t acc = 0;
 262         size_t size, tsz;
 263         size_t elf_buflen;
 264         int nphdr;
 265         unsigned long start;
 266
 267         read_lock(&kclist_lock);
 268         proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
 269         if (buflen == 0 || *fpos >= size) {
 270                 read_unlock(&kclist_lock);
 271                 return 0;
 272         }
 273
 274         /* trim buflen to not go beyond EOF */
 275         if (buflen > size - *fpos)
 276                 buflen = size - *fpos;
 277
 278         /* construct an ELF core header if we'll need some of it */
 279         if (*fpos < elf_buflen) {
 280                 char * elf_buf;
 281
 282                 tsz = elf_buflen - *fpos;
 283                 if (buflen < tsz)
 284                         tsz = buflen;
 285                 elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
 286                 if (!elf_buf) {
 287                         read_unlock(&kclist_lock);
 288                         return -ENOMEM;
 289                 }
 290                 memset(elf_buf, 0, elf_buflen);
 291                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 292                 read_unlock(&kclist_lock);
 293                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 294                         kfree(elf_buf);
 295                         return -EFAULT;
 296                 }
 297                 kfree(elf_buf);
 298                 buflen -= tsz;
 299                 *fpos += tsz;
 300                 buffer += tsz;
 301                 acc += tsz;
 302
 303                 /* leave now if filled buffer already */
 304                 if (buflen == 0)
 305                         return acc;
 306         } else
 307                 read_unlock(&kclist_lock);
 308
 309         /*
 310          * Check to see if our file offset matches with any of
 311          * the addresses in the elf_phdr on our list.
 312          */
 313         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 314         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 315                 tsz = buflen;
 316
 317         while (buflen) {
 318                 struct kcore_list *m;
 319
 320                 read_lock(&kclist_lock);
 321                 for (m=kclist; m; m=m->next) {
 322                         if (start >= m->addr && start < (m->addr+m->size))
 323                                 break;
 324                 }
 325                 read_unlock(&kclist_lock);
 326
 327                 if (m == NULL) {
 328                         if (clear_user(buffer, tsz))
 329                                 return -EFAULT;
 330                 } else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) {
 331                         char * elf_buf;
 332                         struct vm_struct *m;
 333                         unsigned long curstart = start;
 334                         unsigned long cursize = tsz;
 335
 336                         elf_buf = kmalloc(tsz, GFP_KERNEL);
 337                         if (!elf_buf)
 338                                 return -ENOMEM;
 339                         memset(elf_buf, 0, tsz);
 340
 341                         read_lock(&vmlist_lock);
 342                         for (m=vmlist; m && cursize; m=m->next) {
 343                                 unsigned long vmstart;
 344                                 unsigned long vmsize;
 345                                 unsigned long msize = m->size - PAGE_SIZE;
 346
 347                                 if (((unsigned long)m->addr + msize) <
 348                                                                 curstart)
 349                                         continue;
 350                                 if ((unsigned long)m->addr > (curstart +
 351                                                                 cursize))
 352                                         break;
 353                                 vmstart = (curstart < (unsigned long)m->addr ?
 354                                         (unsigned long)m->addr : curstart);
 355                                 if (((unsigned long)m->addr + msize) >
 356                                                         (curstart + cursize))
 357                                         vmsize = curstart + cursize - vmstart;
 358                                 else
 359                                         vmsize = (unsigned long)m->addr +
 360                                                         msize - vmstart;
 361                                 curstart = vmstart + vmsize;
 362                                 cursize -= vmsize;
 363                                 /* don't dump ioremap'd stuff! (TA) */
 364                                 if (m->flags & VM_IOREMAP)
 365                                         continue;
 366                                 memcpy(elf_buf + (vmstart - start),
 367                                         (char *)vmstart, vmsize);
 368                         }
 369                         read_unlock(&vmlist_lock);
 370                         if (copy_to_user(buffer, elf_buf, tsz)) {
 371                                 kfree(elf_buf);
 372                                 return -EFAULT;
 373                         }
 374                         kfree(elf_buf);
 375                 } else {
 376                         if (kern_addr_valid(start)) {
 377                                 unsigned long n;
 378
 379                                 n = copy_to_user(buffer, (char *)start, tsz);
 380                                 /*
 381                                  * We cannot distingush between fault on source
 382                                  * and fault on destination. When this happens
 383                                  * we clear too and hope it will trigger the
 384                                  * EFAULT again.
 385                                  */
 386                                 if (n) {
 387                                         if (clear_user(buffer + tsz - n,
 388                                                                 tsz - n))
 389                                                 return -EFAULT;
 390                                 }
 391                         } else {
 392                                 if (clear_user(buffer, tsz))
 393                                         return -EFAULT;
 394                         }
 395                 }
 396                 buflen -= tsz;
 397                 *fpos += tsz;
 398                 buffer += tsz;
 399                 acc += tsz;
 400                 start += tsz;
 401                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 402         }
 403
 404         return acc;
 405 }