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/elf.h>
  18 #include <linux/elfcore.h>
  19 #include <linux/vmalloc.h>
  20 #include <linux/highmem.h>
  21 #include <linux/init.h>
  22 #include <asm/uaccess.h>
  23 #include <asm/io.h>
  24
  25
  26 static int open_kcore(struct inode * inode, struct file * filp)
  27 {
  28         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  29 }
  30
  31 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
  32
  33 struct file_operations proc_kcore_operations = {
  34         .read           = read_kcore,
  35         .open           = open_kcore,
  36 };
  37
  38 #ifndef kc_vaddr_to_offset
  39 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  40 #endif
  41 #ifndef kc_offset_to_vaddr
  42 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  43 #endif
  44
  45 #define roundup(x, y)  ((((x)+((y)-1))/(y))*(y))
  46
  47 /* An ELF note in memory */
  48 struct memelfnote
  49 {
  50         const char *name;
  51         int type;
  52         unsigned int datasz;
  53         void *data;
  54 };
  55
  56 static struct kcore_list *kclist;
  57 static DEFINE_RWLOCK(kclist_lock);
  58
  59 void
  60 kclist_add(struct kcore_list *new, void *addr, size_t size)
  61 {
  62         new->addr = (unsigned long)addr;
  63         new->size = size;
  64
  65         write_lock(&kclist_lock);
  66         new->next = kclist;
  67         kclist = new;
  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         for (m=kclist; m; m=m->next) {
  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) + 4) +
  88                         sizeof(struct elf_prstatus) +
  89                         sizeof(struct elf_prpsinfo) +
  90                         sizeof(struct task_struct);
  91         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  92         return size + *elf_buflen;
  93 }
  94
  95
  96 /*****************************************************************************/
  97 /*
  98  * determine size of ELF note
  99  */
 100 static int notesize(struct memelfnote *en)
 101 {
 102         int sz;
 103
 104         sz = sizeof(struct elf_note);
 105         sz += roundup(strlen(en->name), 4);
 106         sz += roundup(en->datasz, 4);
 107
 108         return sz;
 109 } /* end notesize() */
 110
 111 /*****************************************************************************/
 112 /*
 113  * store a note in the header buffer
 114  */
 115 static char *storenote(struct memelfnote *men, char *bufp)
 116 {
 117         struct elf_note en;
 118
 119 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 120
 121         en.n_namesz = strlen(men->name);
 122         en.n_descsz = men->datasz;
 123         en.n_type = men->type;
 124
 125         DUMP_WRITE(&en, sizeof(en));
 126         DUMP_WRITE(men->name, en.n_namesz);
 127
 128         /* XXX - cast from long long to long to avoid need for libgcc.a */
 129         bufp = (char*) roundup((unsigned long)bufp,4);
 130         DUMP_WRITE(men->data, men->datasz);
 131         bufp = (char*) roundup((unsigned long)bufp,4);
 132
 133 #undef DUMP_WRITE
 134
 135         return bufp;
 136 } /* end storenote() */
 137
 138 /*
 139  * store an ELF coredump header in the supplied buffer
 140  * nphdr is the number of elf_phdr to insert
 141  */
 142 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 143 {
 144         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 145         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 146         struct elf_phdr *nhdr, *phdr;
 147         struct elfhdr *elf;
 148         struct memelfnote notes[3];
 149         off_t offset = 0;
 150         struct kcore_list *m;
 151
 152         /* setup ELF header */
 153         elf = (struct elfhdr *) bufp;
 154         bufp += sizeof(struct elfhdr);
 155         offset += sizeof(struct elfhdr);
 156         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 157         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 158         elf->e_ident[EI_DATA]   = ELF_DATA;
 159         elf->e_ident[EI_VERSION]= EV_CURRENT;
 160         elf->e_ident[EI_OSABI] = ELF_OSABI;
 161         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 162         elf->e_type     = ET_CORE;
 163         elf->e_machine  = ELF_ARCH;
 164         elf->e_version  = EV_CURRENT;
 165         elf->e_entry    = 0;
 166         elf->e_phoff    = sizeof(struct elfhdr);
 167         elf->e_shoff    = 0;
 168 #if defined(CONFIG_H8300)
 169         elf->e_flags    = ELF_FLAGS;
 170 #else
 171         elf->e_flags    = 0;
 172 #endif
 173         elf->e_ehsize   = sizeof(struct elfhdr);
 174         elf->e_phentsize= sizeof(struct elf_phdr);
 175         elf->e_phnum    = nphdr;
 176         elf->e_shentsize= 0;
 177         elf->e_shnum    = 0;
 178         elf->e_shstrndx = 0;
 179
 180         /* setup ELF PT_NOTE program header */
 181         nhdr = (struct elf_phdr *) bufp;
 182         bufp += sizeof(struct elf_phdr);
 183         offset += sizeof(struct elf_phdr);
 184         nhdr->p_type    = PT_NOTE;
 185         nhdr->p_offset  = 0;
 186         nhdr->p_vaddr   = 0;
 187         nhdr->p_paddr   = 0;
 188         nhdr->p_filesz  = 0;
 189         nhdr->p_memsz   = 0;
 190         nhdr->p_flags   = 0;
 191         nhdr->p_align   = 0;
 192
 193         /* setup ELF PT_LOAD program header for every area */
 194         for (m=kclist; m; m=m->next) {
 195                 phdr = (struct elf_phdr *) bufp;
 196                 bufp += sizeof(struct elf_phdr);
 197                 offset += sizeof(struct elf_phdr);
 198
 199                 phdr->p_type    = PT_LOAD;
 200                 phdr->p_flags   = PF_R|PF_W|PF_X;
 201                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 202                 phdr->p_vaddr   = (size_t)m->addr;
 203                 phdr->p_paddr   = 0;
 204                 phdr->p_filesz  = phdr->p_memsz = m->size;
 205                 phdr->p_align   = PAGE_SIZE;
 206         }
 207
 208         /*
 209          * Set up the notes in similar form to SVR4 core dumps made
 210          * with info from their /proc.
 211          */
 212         nhdr->p_offset  = offset;
 213
 214         /* set up the process status */
 215         notes[0].name = "CORE";
 216         notes[0].type = NT_PRSTATUS;
 217         notes[0].datasz = sizeof(struct elf_prstatus);
 218         notes[0].data = &prstatus;
 219
 220         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 221
 222         nhdr->p_filesz  = notesize(&notes[0]);
 223         bufp = storenote(&notes[0], bufp);
 224
 225         /* set up the process info */
 226         notes[1].name   = "CORE";
 227         notes[1].type   = NT_PRPSINFO;
 228         notes[1].datasz = sizeof(struct elf_prpsinfo);
 229         notes[1].data   = &prpsinfo;
 230
 231         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 232         prpsinfo.pr_state       = 0;
 233         prpsinfo.pr_sname       = 'R';
 234         prpsinfo.pr_zomb        = 0;
 235
 236         strcpy(prpsinfo.pr_fname, "vmlinux");
 237         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 238
 239         nhdr->p_filesz  += notesize(&notes[1]);
 240         bufp = storenote(&notes[1], bufp);
 241
 242         /* set up the task structure */
 243         notes[2].name   = "CORE";
 244         notes[2].type   = NT_TASKSTRUCT;
 245         notes[2].datasz = sizeof(struct task_struct);
 246         notes[2].data   = current;
 247
 248         nhdr->p_filesz  += notesize(&notes[2]);
 249         bufp = storenote(&notes[2], bufp);
 250
 251 } /* end elf_kcore_store_hdr() */
 252
 253 /*****************************************************************************/
 254 /*
 255  * read from the ELF header and then kernel memory
 256  */
 257 static ssize_t
 258 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 259 {
 260         ssize_t acc = 0;
 261         size_t size, tsz;
 262         size_t elf_buflen;
 263         int nphdr;
 264         unsigned long start;
 265
 266         read_lock(&kclist_lock);
 267         proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
 268         if (buflen == 0 || *fpos >= size) {
 269                 read_unlock(&kclist_lock);
 270                 return 0;
 271         }
 272
 273         /* trim buflen to not go beyond EOF */
 274         if (buflen > size - *fpos)
 275                 buflen = size - *fpos;
 276
 277         /* construct an ELF core header if we'll need some of it */
 278         if (*fpos < elf_buflen) {
 279                 char * elf_buf;
 280
 281                 tsz = elf_buflen - *fpos;
 282                 if (buflen < tsz)
 283                         tsz = buflen;
 284                 elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
 285                 if (!elf_buf) {
 286                         read_unlock(&kclist_lock);
 287                         return -ENOMEM;
 288                 }
 289                 memset(elf_buf, 0, elf_buflen);
 290                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 291                 read_unlock(&kclist_lock);
 292                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 293                         kfree(elf_buf);
 294                         return -EFAULT;
 295                 }
 296                 kfree(elf_buf);
 297                 buflen -= tsz;
 298                 *fpos += tsz;
 299                 buffer += tsz;
 300                 acc += tsz;
 301
 302                 /* leave now if filled buffer already */
 303                 if (buflen == 0)
 304                         return acc;
 305         } else
 306                 read_unlock(&kclist_lock);
 307
 308         /*
 309          * Check to see if our file offset matches with any of
 310          * the addresses in the elf_phdr on our list.
 311          */
 312         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 313         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 314                 tsz = buflen;
 315
 316         while (buflen) {
 317                 struct kcore_list *m;
 318
 319                 read_lock(&kclist_lock);
 320                 for (m=kclist; m; m=m->next) {
 321                         if (start >= m->addr && start < (m->addr+m->size))
 322                                 break;
 323                 }
 324                 read_unlock(&kclist_lock);
 325
 326                 if (m == NULL) {
 327                         if (clear_user(buffer, tsz))
 328                                 return -EFAULT;
 329                 } else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) {
 330                         char * elf_buf;
 331                         struct vm_struct *m;
 332                         unsigned long curstart = start;
 333                         unsigned long cursize = tsz;
 334
 335                         elf_buf = kmalloc(tsz, GFP_KERNEL);
 336                         if (!elf_buf)
 337                                 return -ENOMEM;
 338                         memset(elf_buf, 0, tsz);
 339
 340                         read_lock(&vmlist_lock);
 341                         for (m=vmlist; m && cursize; m=m->next) {
 342                                 unsigned long vmstart;
 343                                 unsigned long vmsize;
 344                                 unsigned long msize = m->size - PAGE_SIZE;
 345
 346                                 if (((unsigned long)m->addr + msize) <
 347                                                                 curstart)
 348                                         continue;
 349                                 if ((unsigned long)m->addr > (curstart +
 350                                                                 cursize))
 351                                         break;
 352                                 vmstart = (curstart < (unsigned long)m->addr ?
 353                                         (unsigned long)m->addr : curstart);
 354                                 if (((unsigned long)m->addr + msize) >
 355                                                         (curstart + cursize))
 356                                         vmsize = curstart + cursize - vmstart;
 357                                 else
 358                                         vmsize = (unsigned long)m->addr +
 359                                                         msize - vmstart;
 360                                 curstart = vmstart + vmsize;
 361                                 cursize -= vmsize;
 362                                 /* don't dump ioremap'd stuff! (TA) */
 363                                 if (m->flags & VM_IOREMAP)
 364                                         continue;
 365                                 memcpy(elf_buf + (vmstart - start),
 366                                         (char *)vmstart, vmsize);
 367                         }
 368                         read_unlock(&vmlist_lock);
 369                         if (copy_to_user(buffer, elf_buf, tsz)) {
 370                                 kfree(elf_buf);
 371                                 return -EFAULT;
 372                         }
 373                         kfree(elf_buf);
 374                 } else {
 375                         if (kern_addr_valid(start)) {
 376                                 unsigned long n;
 377
 378                                 n = copy_to_user(buffer, (char *)start, tsz);
 379                                 /*
 380                                  * We cannot distingush between fault on source
 381                                  * and fault on destination. When this happens
 382                                  * we clear too and hope it will trigger the
 383                                  * EFAULT again.
 384                                  */
 385                                 if (n) {
 386                                         if (clear_user(buffer + tsz - n,
 387                                                                 tsz - n))
 388                                                 return -EFAULT;
 389                                 }
 390                         } else {
 391                                 if (clear_user(buffer, tsz))
 392                                         return -EFAULT;
 393                         }
 394                 }
 395                 buflen -= tsz;
 396                 *fpos += tsz;
 397                 buffer += tsz;
 398                 acc += tsz;
 399                 start += tsz;
 400                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 401         }
 402
 403         return acc;
 404 }