fs/proc/kcore.c

   1 /*
   2  *      fs/proc/kcore.c kernel ELF/AOUT 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@sco.com>
   8  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@sco.com>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/mm.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/user.h>
  15 #include <linux/a.out.h>
  16 #include <linux/elf.h>
  17 #include <linux/elfcore.h>
  18 #include <linux/vmalloc.h>
  19 #include <asm/uaccess.h>
  20 #include <asm/io.h>
  21
  22
  23 static int open_kcore(struct inode * inode, struct file * filp)
  24 {
  25         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  26 }
  27
  28 static ssize_t read_kcore(struct file *, char *, size_t, loff_t *);
  29
  30 struct file_operations proc_kcore_operations = {
  31         read:           read_kcore,
  32         open:           open_kcore,
  33 };
  34
  35 #ifdef CONFIG_KCORE_AOUT
  36 static ssize_t read_kcore(struct file *file, char *buf, size_t count, loff_t *ppos)
  37 {
  38         unsigned long long p = *ppos, memsize;
  39         ssize_t read;
  40         ssize_t count1;
  41         char * pnt;
  42         struct user dump;
  43 #if defined (__i386__) || defined (__mc68000__)
  44 #       define FIRST_MAPPED     PAGE_SIZE       /* we don't have page 0 mapped on x86.. */
  45 #else
  46 #       define FIRST_MAPPED     0
  47 #endif
  48
  49         memset(&dump, 0, sizeof(struct user));
  50         dump.magic = CMAGIC;
  51         dump.u_dsize = (virt_to_phys(high_memory) >> PAGE_SHIFT);
  52 #if defined (__i386__)
  53         dump.start_code = PAGE_OFFSET;
  54 #endif
  55 #ifdef __alpha__
  56         dump.start_data = PAGE_OFFSET;
  57 #endif
  58
  59         memsize = virt_to_phys(high_memory);
  60         if (p >= memsize)
  61                 return 0;
  62         if (count > memsize - p)
  63                 count = memsize - p;
  64         read = 0;
  65
  66         if (p < sizeof(struct user) && count > 0) {
  67                 count1 = count;
  68                 if (p + count1 > sizeof(struct user))
  69                         count1 = sizeof(struct user)-p;
  70                 pnt = (char *) &dump + p;
  71                 if (copy_to_user(buf,(void *) pnt, count1))
  72                         return -EFAULT;
  73                 buf += count1;
  74                 p += count1;
  75                 count -= count1;
  76                 read += count1;
  77         }
  78
  79         if (count > 0 && p < PAGE_SIZE + FIRST_MAPPED) {
  80                 count1 = PAGE_SIZE + FIRST_MAPPED - p;
  81                 if (count1 > count)
  82                         count1 = count;
  83                 if (clear_user(buf, count1))
  84                         return -EFAULT;
  85                 buf += count1;
  86                 p += count1;
  87                 count -= count1;
  88                 read += count1;
  89         }
  90         if (count > 0) {
  91                 if (copy_to_user(buf, (void *) (PAGE_OFFSET+p-PAGE_SIZE), count))
  92                         return -EFAULT;
  93                 read += count;
  94         }
  95         *ppos += read;
  96         return read;
  97 }
  98 #else /* CONFIG_KCORE_AOUT */
  99
 100 #define roundup(x, y)  ((((x)+((y)-1))/(y))*(y))
 101
 102 /* An ELF note in memory */
 103 struct memelfnote
 104 {
 105         const char *name;
 106         int type;
 107         unsigned int datasz;
 108         void *data;
 109 };
 110
 111 extern char saved_command_line[];
 112
 113 static size_t get_kcore_size(int *num_vma, size_t *elf_buflen)
 114 {
 115         size_t try, size = 0;
 116         struct vm_struct *m;
 117
 118         *num_vma = 0;
 119         if (!vmlist) {
 120                 *elf_buflen = PAGE_SIZE;
 121                 return ((size_t)high_memory - PAGE_OFFSET + PAGE_SIZE);
 122         }
 123
 124         for (m=vmlist; m; m=m->next) {
 125                 if (m->flags & VM_IOREMAP) /* don't dump ioremap'd stuff! (TA) */
 126                         continue;
 127                 try = (size_t)m->addr + m->size;
 128                 if (try > size)
 129                         size = try;
 130                 *num_vma = *num_vma + 1;
 131         }
 132         *elf_buflen =   sizeof(struct elfhdr) +
 133                         (*num_vma + 2)*sizeof(struct elf_phdr) +
 134                         3 * sizeof(struct memelfnote);
 135         *elf_buflen = PAGE_ALIGN(*elf_buflen);
 136         return (size - PAGE_OFFSET + *elf_buflen);
 137 }
 138
 139
 140 /*****************************************************************************/
 141 /*
 142  * determine size of ELF note
 143  */
 144 static int notesize(struct memelfnote *en)
 145 {
 146         int sz;
 147
 148         sz = sizeof(struct elf_note);
 149         sz += roundup(strlen(en->name), 4);
 150         sz += roundup(en->datasz, 4);
 151
 152         return sz;
 153 } /* end notesize() */
 154
 155 /*****************************************************************************/
 156 /*
 157  * store a note in the header buffer
 158  */
 159 static char *storenote(struct memelfnote *men, char *bufp)
 160 {
 161         struct elf_note en;
 162
 163 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 164
 165         en.n_namesz = strlen(men->name);
 166         en.n_descsz = men->datasz;
 167         en.n_type = men->type;
 168
 169         DUMP_WRITE(&en, sizeof(en));
 170         DUMP_WRITE(men->name, en.n_namesz);
 171
 172         /* XXX - cast from long long to long to avoid need for libgcc.a */
 173         bufp = (char*) roundup((unsigned long)bufp,4);
 174         DUMP_WRITE(men->data, men->datasz);
 175         bufp = (char*) roundup((unsigned long)bufp,4);
 176
 177 #undef DUMP_WRITE
 178
 179         return bufp;
 180 } /* end storenote() */
 181
 182 /*
 183  * store an ELF coredump header in the supplied buffer
 184  * num_vma is the number of elements in vmlist
 185  */
 186 static void elf_kcore_store_hdr(char *bufp, int num_vma, int dataoff)
 187 {
 188         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 189         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 190         struct elf_phdr *nhdr, *phdr;
 191         struct elfhdr *elf;
 192         struct memelfnote notes[3];
 193         off_t offset = 0;
 194         struct vm_struct *m;
 195
 196         /* setup ELF header */
 197         elf = (struct elfhdr *) bufp;
 198         bufp += sizeof(struct elfhdr);
 199         offset += sizeof(struct elfhdr);
 200         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 201         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 202         elf->e_ident[EI_DATA]   = ELF_DATA;
 203         elf->e_ident[EI_VERSION]= EV_CURRENT;
 204         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 205         elf->e_type     = ET_CORE;
 206         elf->e_machine  = ELF_ARCH;
 207         elf->e_version  = EV_CURRENT;
 208         elf->e_entry    = 0;
 209         elf->e_phoff    = sizeof(struct elfhdr);
 210         elf->e_shoff    = 0;
 211         elf->e_flags    = 0;
 212         elf->e_ehsize   = sizeof(struct elfhdr);
 213         elf->e_phentsize= sizeof(struct elf_phdr);
 214         elf->e_phnum    = 2 + num_vma;
 215         elf->e_shentsize= 0;
 216         elf->e_shnum    = 0;
 217         elf->e_shstrndx = 0;
 218
 219         /* setup ELF PT_NOTE program header */
 220         nhdr = (struct elf_phdr *) bufp;
 221         bufp += sizeof(struct elf_phdr);
 222         offset += sizeof(struct elf_phdr);
 223         nhdr->p_type    = PT_NOTE;
 224         nhdr->p_offset  = 0;
 225         nhdr->p_vaddr   = 0;
 226         nhdr->p_paddr   = 0;
 227         nhdr->p_filesz  = 0;
 228         nhdr->p_memsz   = 0;
 229         nhdr->p_flags   = 0;
 230         nhdr->p_align   = 0;
 231
 232         /* setup ELF PT_LOAD program header for the
 233          * virtual range 0xc0000000 -> high_memory */
 234         phdr = (struct elf_phdr *) bufp;
 235         bufp += sizeof(struct elf_phdr);
 236         offset += sizeof(struct elf_phdr);
 237         phdr->p_type    = PT_LOAD;
 238         phdr->p_flags   = PF_R|PF_W|PF_X;
 239         phdr->p_offset  = dataoff;
 240         phdr->p_vaddr   = PAGE_OFFSET;
 241         phdr->p_paddr   = __pa(PAGE_OFFSET);
 242         phdr->p_filesz  = phdr->p_memsz = ((unsigned long)high_memory - PAGE_OFFSET);
 243         phdr->p_align   = PAGE_SIZE;
 244
 245         /* setup ELF PT_LOAD program header for every vmalloc'd area */
 246         for (m=vmlist; m; m=m->next) {
 247                 if (m->flags & VM_IOREMAP) /* don't dump ioremap'd stuff! (TA) */
 248                         continue;
 249
 250                 phdr = (struct elf_phdr *) bufp;
 251                 bufp += sizeof(struct elf_phdr);
 252                 offset += sizeof(struct elf_phdr);
 253
 254                 phdr->p_type    = PT_LOAD;
 255                 phdr->p_flags   = PF_R|PF_W|PF_X;
 256                 phdr->p_offset  = (size_t)m->addr - PAGE_OFFSET + dataoff;
 257                 phdr->p_vaddr   = (size_t)m->addr;
 258                 phdr->p_paddr   = __pa(m->addr);
 259                 phdr->p_filesz  = phdr->p_memsz = m->size;
 260                 phdr->p_align   = PAGE_SIZE;
 261         }
 262
 263         /*
 264          * Set up the notes in similar form to SVR4 core dumps made
 265          * with info from their /proc.
 266          */
 267         nhdr->p_offset  = offset;
 268
 269         /* set up the process status */
 270         notes[0].name = "CORE";
 271         notes[0].type = NT_PRSTATUS;
 272         notes[0].datasz = sizeof(struct elf_prstatus);
 273         notes[0].data = &prstatus;
 274
 275         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 276
 277         nhdr->p_filesz  = notesize(&notes[0]);
 278         bufp = storenote(&notes[0], bufp);
 279
 280         /* set up the process info */
 281         notes[1].name   = "CORE";
 282         notes[1].type   = NT_PRPSINFO;
 283         notes[1].datasz = sizeof(struct elf_prpsinfo);
 284         notes[1].data   = &prpsinfo;
 285
 286         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 287         prpsinfo.pr_state       = 0;
 288         prpsinfo.pr_sname       = 'R';
 289         prpsinfo.pr_zomb        = 0;
 290
 291         strcpy(prpsinfo.pr_fname, "vmlinux");
 292         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 293
 294         nhdr->p_filesz  = notesize(&notes[1]);
 295         bufp = storenote(&notes[1], bufp);
 296
 297         /* set up the task structure */
 298         notes[2].name   = "CORE";
 299         notes[2].type   = NT_TASKSTRUCT;
 300         notes[2].datasz = sizeof(struct task_struct);
 301         notes[2].data   = current;
 302
 303         nhdr->p_filesz  = notesize(&notes[2]);
 304         bufp = storenote(&notes[2], bufp);
 305
 306 } /* end elf_kcore_store_hdr() */
 307
 308 /*****************************************************************************/
 309 /*
 310  * read from the ELF header and then kernel memory
 311  */
 312 static ssize_t read_kcore(struct file *file, char *buffer, size_t buflen, loff_t *fpos)
 313 {
 314         ssize_t acc = 0;
 315         size_t size, tsz;
 316         size_t elf_buflen;
 317         int num_vma;
 318
 319         read_lock(&vmlist_lock);
 320         proc_root_kcore->size = size = get_kcore_size(&num_vma, &elf_buflen);
 321         if (buflen == 0 || *fpos >= size) {
 322                 read_unlock(&vmlist_lock);
 323                 return 0;
 324         }
 325
 326         /* trim buflen to not go beyond EOF */
 327         if (buflen > size - *fpos)
 328                 buflen = size - *fpos;
 329
 330         /* construct an ELF core header if we'll need some of it */
 331         if (*fpos < elf_buflen) {
 332                 char * elf_buf;
 333
 334                 tsz = elf_buflen - *fpos;
 335                 if (buflen < tsz)
 336                         tsz = buflen;
 337                 elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
 338                 if (!elf_buf) {
 339                         read_unlock(&vmlist_lock);
 340                         return -ENOMEM;
 341                 }
 342                 memset(elf_buf, 0, elf_buflen);
 343                 elf_kcore_store_hdr(elf_buf, num_vma, elf_buflen);
 344                 read_unlock(&vmlist_lock);
 345                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 346                         kfree(elf_buf);
 347                         return -EFAULT;
 348                 }
 349                 kfree(elf_buf);
 350                 buflen -= tsz;
 351                 *fpos += tsz;
 352                 buffer += tsz;
 353                 acc += tsz;
 354
 355                 /* leave now if filled buffer already */
 356                 if (buflen == 0)
 357                         return acc;
 358         } else
 359                 read_unlock(&vmlist_lock);
 360
 361         /* where page 0 not mapped, write zeros into buffer */
 362 #if defined (__i386__) || defined (__mc68000__)
 363         if (*fpos < PAGE_SIZE + elf_buflen) {
 364                 /* work out how much to clear */
 365                 tsz = PAGE_SIZE + elf_buflen - *fpos;
 366                 if (buflen < tsz)
 367                         tsz = buflen;
 368
 369                 /* write zeros to buffer */
 370                 if (clear_user(buffer, tsz))
 371                         return -EFAULT;
 372                 buflen -= tsz;
 373                 *fpos += tsz;
 374                 buffer += tsz;
 375                 acc += tsz;
 376
 377                 /* leave now if filled buffer already */
 378                 if (buflen == 0)
 379                         return tsz;
 380         }
 381 #endif
 382         /* fill the remainder of the buffer from kernel VM space */
 383         if (copy_to_user(buffer, __va(*fpos - elf_buflen), buflen))
 384                 return -EFAULT;
 385
 386         acc += buflen;
 387         *fpos += buflen;
 388         return acc;
 389 }
 390 #endif /* CONFIG_KCORE_AOUT */