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/a.out.h> 16 #include <linux/capability.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 #define CORE_STR "CORE" 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 const 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 /* An ELF note in memory */ 47 struct memelfnote 48 { 49 const char *name; 50 int type; 51 unsigned int datasz; 52 void *data; 53 }; 54 55 static struct kcore_list *kclist; 56 static DEFINE_RWLOCK(kclist_lock); 57 58 void 59 kclist_add(struct kcore_list *new, void *addr, size_t size) 60 { 61 new->addr = (unsigned long)addr; 62 new->size = size; 63 64 write_lock(&kclist_lock); 65 new->next = kclist; 66 kclist = new; 67 write_unlock(&kclist_lock); 68 } 69 70 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) 71 { 72 size_t try, size; 73 struct kcore_list *m; 74 75 *nphdr = 1; /* PT_NOTE */ 76 size = 0; 77 78 for (m=kclist; m; m=m->next) { 79 try = kc_vaddr_to_offset((size_t)m->addr + m->size); 80 if (try > size) 81 size = try; 82 *nphdr = *nphdr + 1; 83 } 84 *elf_buflen = sizeof(struct elfhdr) + 85 (*nphdr + 2)*sizeof(struct elf_phdr) + 86 3 * ((sizeof(struct elf_note)) + 87 roundup(sizeof(CORE_STR), 4)) + 88 roundup(sizeof(struct elf_prstatus), 4) + 89 roundup(sizeof(struct elf_prpsinfo), 4) + 90 roundup(sizeof(struct task_struct), 4); 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) + 1), 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) + 1; 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_STR; 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(¬es[0]); 223 bufp = storenote(¬es[0], bufp); 224 225 /* set up the process info */ 226 notes[1].name = CORE_STR; 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(¬es[1]); 240 bufp = storenote(¬es[1], bufp); 241 242 /* set up the task structure */ 243 notes[2].name = CORE_STR; 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(¬es[2]); 249 bufp = storenote(¬es[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 = kzalloc(elf_buflen, GFP_ATOMIC); 285 if (!elf_buf) { 286 read_unlock(&kclist_lock); 287 return -ENOMEM; 288 } 289 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); 290 read_unlock(&kclist_lock); 291 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { 292 kfree(elf_buf); 293 return -EFAULT; 294 } 295 kfree(elf_buf); 296 buflen -= tsz; 297 *fpos += tsz; 298 buffer += tsz; 299 acc += tsz; 300 301 /* leave now if filled buffer already */ 302 if (buflen == 0) 303 return acc; 304 } else 305 read_unlock(&kclist_lock); 306 307 /* 308 * Check to see if our file offset matches with any of 309 * the addresses in the elf_phdr on our list. 310 */ 311 start = kc_offset_to_vaddr(*fpos - elf_buflen); 312 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) 313 tsz = buflen; 314 315 while (buflen) { 316 struct kcore_list *m; 317 318 read_lock(&kclist_lock); 319 for (m=kclist; m; m=m->next) { 320 if (start >= m->addr && start < (m->addr+m->size)) 321 break; 322 } 323 read_unlock(&kclist_lock); 324 325 if (m == NULL) { 326 if (clear_user(buffer, tsz)) 327 return -EFAULT; 328 } else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) { 329 char * elf_buf; 330 struct vm_struct *m; 331 unsigned long curstart = start; 332 unsigned long cursize = tsz; 333 334 elf_buf = kzalloc(tsz, GFP_KERNEL); 335 if (!elf_buf) 336 return -ENOMEM; 337 338 read_lock(&vmlist_lock); 339 for (m=vmlist; m && cursize; m=m->next) { 340 unsigned long vmstart; 341 unsigned long vmsize; 342 unsigned long msize = m->size - PAGE_SIZE; 343 344 if (((unsigned long)m->addr + msize) < 345 curstart) 346 continue; 347 if ((unsigned long)m->addr > (curstart + 348 cursize)) 349 break; 350 vmstart = (curstart < (unsigned long)m->addr ? 351 (unsigned long)m->addr : curstart); 352 if (((unsigned long)m->addr + msize) > 353 (curstart + cursize)) 354 vmsize = curstart + cursize - vmstart; 355 else 356 vmsize = (unsigned long)m->addr + 357 msize - vmstart; 358 curstart = vmstart + vmsize; 359 cursize -= vmsize; 360 /* don't dump ioremap'd stuff! (TA) */ 361 if (m->flags & VM_IOREMAP) 362 continue; 363 memcpy(elf_buf + (vmstart - start), 364 (char *)vmstart, vmsize); 365 } 366 read_unlock(&vmlist_lock); 367 if (copy_to_user(buffer, elf_buf, tsz)) { 368 kfree(elf_buf); 369 return -EFAULT; 370 } 371 kfree(elf_buf); 372 } else { 373 if (kern_addr_valid(start)) { 374 unsigned long n; 375 376 n = copy_to_user(buffer, (char *)start, tsz); 377 /* 378 * We cannot distingush between fault on source 379 * and fault on destination. When this happens 380 * we clear too and hope it will trigger the 381 * EFAULT again. 382 */ 383 if (n) { 384 if (clear_user(buffer + tsz - n, 385 n)) 386 return -EFAULT; 387 } 388 } else { 389 if (clear_user(buffer, tsz)) 390 return -EFAULT; 391 } 392 } 393 buflen -= tsz; 394 *fpos += tsz; 395 buffer += tsz; 396 acc += tsz; 397 start += tsz; 398 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); 399 } 400 401 return acc; 402 } 403