usr/src/boot/sys/boot/common/load_elf_obj.c

   1 /*-
   2  * Copyright (c) 2004 Ian Dowse <iedowse@freebsd.org>
   3  * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
   4  * Copyright (c) 1998 Peter Wemm <peter@freebsd.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/exec.h>
  34 #include <sys/linker.h>
  35 #include <sys/module.h>
  36 #include <inttypes.h>
  37 #include <string.h>
  38 #include <machine/elf.h>
  39 #include <stand.h>
  40 #define FREEBSD_ELF
  41 #include <link.h>
  42
  43 #include "bootstrap.h"
  44
  45 #define COPYOUT(s,d,l)  archsw.arch_copyout((vm_offset_t)(s), d, l)
  46
  47 #if defined(__i386__) && __ELF_WORD_SIZE == 64
  48 #undef ELF_TARG_CLASS
  49 #undef ELF_TARG_MACH
  50 #define ELF_TARG_CLASS  ELFCLASS64
  51 #define ELF_TARG_MACH   EM_X86_64
  52 #endif
  53
  54 typedef struct elf_file {
  55         Elf_Ehdr        hdr;
  56         Elf_Shdr        *e_shdr;
  57
  58         int             symtabindex;    /* Index of symbol table */
  59         int             shstrindex;     /* Index of section name string table */
  60
  61         int             fd;
  62         vm_offset_t     off;
  63 } *elf_file_t;
  64
  65 static int __elfN(obj_loadimage)(struct preloaded_file *mp, elf_file_t ef,
  66     u_int64_t loadaddr);
  67 static int __elfN(obj_lookup_set)(struct preloaded_file *mp, elf_file_t ef,
  68     const char *name, Elf_Addr *startp, Elf_Addr *stopp, int *countp);
  69 static int __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
  70     Elf_Addr p, void *val, size_t len);
  71 static int __elfN(obj_parse_modmetadata)(struct preloaded_file *mp,
  72     elf_file_t ef);
  73 static Elf_Addr __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx);
  74
  75 const char      *__elfN(obj_kerneltype) = "elf kernel";
  76 const char      *__elfN(obj_moduletype) = "elf obj module";
  77
  78 /*
  79  * Attempt to load the file (file) as an ELF module.  It will be stored at
  80  * (dest), and a pointer to a module structure describing the loaded object
  81  * will be saved in (result).
  82  */
  83 int
  84 __elfN(obj_loadfile)(char *filename, u_int64_t dest,
  85     struct preloaded_file **result)
  86 {
  87         struct preloaded_file *fp, *kfp;
  88         struct elf_file ef;
  89         Elf_Ehdr *hdr;
  90         int err;
  91         ssize_t bytes_read;
  92
  93         fp = NULL;
  94         bzero(&ef, sizeof(struct elf_file));
  95
  96         /*
  97          * Open the image, read and validate the ELF header
  98          */
  99         if (filename == NULL)   /* can't handle nameless */
 100                 return(EFTYPE);
 101         if ((ef.fd = open(filename, O_RDONLY)) == -1)
 102                 return(errno);
 103
 104         hdr = &ef.hdr;
 105         bytes_read = read(ef.fd, hdr, sizeof(*hdr));
 106         if (bytes_read != sizeof(*hdr)) {
 107                 err = EFTYPE;   /* could be EIO, but may be small file */
 108                 goto oerr;
 109         }
 110
 111         /* Is it ELF? */
 112         if (!IS_ELF(*hdr)) {
 113                 err = EFTYPE;
 114                 goto oerr;
 115         }
 116         if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || /* Layout ? */
 117             hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
 118             hdr->e_ident[EI_VERSION] != EV_CURRENT ||   /* Version ? */
 119             hdr->e_version != EV_CURRENT ||
 120             hdr->e_machine != ELF_TARG_MACH ||          /* Machine ? */
 121             hdr->e_type != ET_REL) {
 122                 err = EFTYPE;
 123                 goto oerr;
 124         }
 125
 126         if (hdr->e_shnum * hdr->e_shentsize == 0 || hdr->e_shoff == 0 ||
 127             hdr->e_shentsize != sizeof(Elf_Shdr)) {
 128                 err = EFTYPE;
 129                 goto oerr;
 130         }
 131
 132         kfp = file_findfile(NULL, __elfN(obj_kerneltype));
 133         if (kfp == NULL) {
 134                 printf("elf" __XSTRING(__ELF_WORD_SIZE)
 135                     "_obj_loadfile: can't load module before kernel\n");
 136                 err = EPERM;
 137                 goto oerr;
 138         }
 139
 140         if (archsw.arch_loadaddr != NULL)
 141                 dest = archsw.arch_loadaddr(LOAD_ELF, hdr, dest);
 142         else
 143                 dest = roundup(dest, PAGE_SIZE);
 144
 145         /*
 146          * Ok, we think we should handle this.
 147          */
 148         fp = file_alloc();
 149         if (fp == NULL) {
 150                 printf("elf" __XSTRING(__ELF_WORD_SIZE)
 151                     "_obj_loadfile: cannot allocate module info\n");
 152                 err = EPERM;
 153                 goto out;
 154         }
 155         fp->f_name = strdup(filename);
 156         fp->f_type = strdup(__elfN(obj_moduletype));
 157
 158         printf("%s ", filename);
 159
 160         fp->f_size = __elfN(obj_loadimage)(fp, &ef, dest);
 161         if (fp->f_size == 0 || fp->f_addr == 0)
 162                 goto ioerr;
 163
 164         /* save exec header as metadata */
 165         file_addmetadata(fp, MODINFOMD_ELFHDR, sizeof(*hdr), hdr);
 166
 167         /* Load OK, return module pointer */
 168         *result = (struct preloaded_file *)fp;
 169         err = 0;
 170         goto out;
 171
 172 ioerr:
 173         err = EIO;
 174 oerr:
 175         file_discard(fp);
 176 out:
 177         close(ef.fd);
 178         if (ef.e_shdr != NULL)
 179                 free(ef.e_shdr);
 180
 181         return(err);
 182 }
 183
 184 /*
 185  * With the file (fd) open on the image, and (ehdr) containing
 186  * the Elf header, load the image at (off)
 187  */
 188 static int
 189 __elfN(obj_loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
 190 {
 191         Elf_Ehdr *hdr;
 192         Elf_Shdr *shdr, *cshdr, *lshdr;
 193         vm_offset_t firstaddr, lastaddr;
 194         int i, nsym, res, ret, shdrbytes, symstrindex;
 195
 196         ret = 0;
 197         firstaddr = lastaddr = (vm_offset_t)off;
 198         hdr = &ef->hdr;
 199         ef->off = (vm_offset_t)off;
 200
 201         /* Read in the section headers. */
 202         shdrbytes = hdr->e_shnum * hdr->e_shentsize;
 203         shdr = alloc_pread(ef->fd, (off_t)hdr->e_shoff, shdrbytes);
 204         if (shdr == NULL) {
 205                 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
 206                     "_obj_loadimage: read section headers failed\n");
 207                 goto out;
 208         }
 209         ef->e_shdr = shdr;
 210
 211         /*
 212          * Decide where to load everything, but don't read it yet.
 213          * We store the load address as a non-zero sh_addr value.
 214          * Start with the code/data and bss.
 215          */
 216         for (i = 0; i < hdr->e_shnum; i++)
 217                 shdr[i].sh_addr = 0;
 218         for (i = 0; i < hdr->e_shnum; i++) {
 219                 if (shdr[i].sh_size == 0)
 220                         continue;
 221                 switch (shdr[i].sh_type) {
 222                 case SHT_PROGBITS:
 223                 case SHT_NOBITS:
 224                         lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
 225                         shdr[i].sh_addr = (Elf_Addr)lastaddr;
 226                         lastaddr += shdr[i].sh_size;
 227                         break;
 228                 }
 229         }
 230
 231         /* Symbols. */
 232         nsym = 0;
 233         for (i = 0; i < hdr->e_shnum; i++) {
 234                 switch (shdr[i].sh_type) {
 235                 case SHT_SYMTAB:
 236                         nsym++;
 237                         ef->symtabindex = i;
 238                         shdr[i].sh_addr = (Elf_Addr)lastaddr;
 239                         lastaddr += shdr[i].sh_size;
 240                         break;
 241                 }
 242         }
 243         if (nsym != 1) {
 244                 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
 245                     "_obj_loadimage: file has no valid symbol table\n");
 246                 goto out;
 247         }
 248         lastaddr = roundup(lastaddr, shdr[ef->symtabindex].sh_addralign);
 249         shdr[ef->symtabindex].sh_addr = (Elf_Addr)lastaddr;
 250         lastaddr += shdr[ef->symtabindex].sh_size;
 251
 252         symstrindex = shdr[ef->symtabindex].sh_link;
 253         if (symstrindex < 0 || symstrindex >= hdr->e_shnum ||
 254             shdr[symstrindex].sh_type != SHT_STRTAB) {
 255                 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
 256                     "_obj_loadimage: file has invalid symbol strings\n");
 257                 goto out;
 258         }
 259         lastaddr = roundup(lastaddr, shdr[symstrindex].sh_addralign);
 260         shdr[symstrindex].sh_addr = (Elf_Addr)lastaddr;
 261         lastaddr += shdr[symstrindex].sh_size;
 262
 263         /* Section names. */
 264         if (hdr->e_shstrndx == 0 || hdr->e_shstrndx >= hdr->e_shnum ||
 265             shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
 266                 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
 267                     "_obj_loadimage: file has no section names\n");
 268                 goto out;
 269         }
 270         ef->shstrindex = hdr->e_shstrndx;
 271         lastaddr = roundup(lastaddr, shdr[ef->shstrindex].sh_addralign);
 272         shdr[ef->shstrindex].sh_addr = (Elf_Addr)lastaddr;
 273         lastaddr += shdr[ef->shstrindex].sh_size;
 274
 275         /* Relocation tables. */
 276         for (i = 0; i < hdr->e_shnum; i++) {
 277                 switch (shdr[i].sh_type) {
 278                 case SHT_REL:
 279                 case SHT_RELA:
 280                         lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
 281                         shdr[i].sh_addr = (Elf_Addr)lastaddr;
 282                         lastaddr += shdr[i].sh_size;
 283                         break;
 284                 }
 285         }
 286
 287         /* Clear the whole area, including bss regions. */
 288         kern_bzero(firstaddr, lastaddr - firstaddr);
 289
 290         /* Figure section with the lowest file offset we haven't loaded yet. */
 291         for (cshdr = NULL; /* none */; /* none */)
 292         {
 293                 /*
 294                  * Find next section to load. The complexity of this loop is
 295                  * O(n^2), but with  the number of sections being typically
 296                  * small, we do not care.
 297                  */
 298                 lshdr = cshdr;
 299
 300                 for (i = 0; i < hdr->e_shnum; i++) {
 301                         if (shdr[i].sh_addr == 0 ||
 302                             shdr[i].sh_type == SHT_NOBITS)
 303                                 continue;
 304                         /* Skip sections that were loaded already. */
 305                         if (lshdr != NULL &&
 306                             lshdr->sh_offset >= shdr[i].sh_offset)
 307                                 continue;
 308                         /* Find section with smallest offset. */
 309                         if (cshdr == lshdr ||
 310                             cshdr->sh_offset > shdr[i].sh_offset)
 311                                 cshdr = &shdr[i];
 312                 }
 313
 314                 if (cshdr == lshdr)
 315                         break;
 316
 317                 if (kern_pread(ef->fd, (vm_offset_t)cshdr->sh_addr,
 318                     cshdr->sh_size, (off_t)cshdr->sh_offset) != 0) {
 319                         printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
 320                             "_obj_loadimage: read failed\n");
 321                         goto out;
 322                 }
 323         }
 324
 325         file_addmetadata(fp, MODINFOMD_SHDR, shdrbytes, shdr);
 326
 327         res = __elfN(obj_parse_modmetadata)(fp, ef);
 328         if (res != 0)
 329                 goto out;
 330
 331         ret = lastaddr - firstaddr;
 332         fp->f_addr = firstaddr;
 333
 334         printf("size 0x%lx at 0x%lx", (u_long)ret, (u_long)firstaddr);
 335
 336 out:
 337         printf("\n");
 338         return ret;
 339 }
 340
 341 #if defined(__i386__) && __ELF_WORD_SIZE == 64
 342 struct mod_metadata64 {
 343         int             md_version;     /* structure version MDTV_* */
 344         int             md_type;        /* type of entry MDT_* */
 345         u_int64_t       md_data;        /* specific data */
 346         u_int64_t       md_cval;        /* common string label */
 347 };
 348 #endif
 349
 350 int
 351 __elfN(obj_parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
 352 {
 353         struct mod_metadata md;
 354 #if defined(__i386__) && __ELF_WORD_SIZE == 64
 355         struct mod_metadata64 md64;
 356 #endif
 357         struct mod_depend *mdepend;
 358         struct mod_version mver;
 359         char *s;
 360         int error, modcnt, minfolen;
 361         Elf_Addr v, p, p_stop;
 362
 363         if (__elfN(obj_lookup_set)(fp, ef, "modmetadata_set", &p, &p_stop,
 364             &modcnt) != 0)
 365                 return 0;
 366
 367         modcnt = 0;
 368         while (p < p_stop) {
 369                 COPYOUT(p, &v, sizeof(v));
 370                 error = __elfN(obj_reloc_ptr)(fp, ef, p, &v, sizeof(v));
 371                 if (error != 0)
 372                         return (error);
 373 #if defined(__i386__) && __ELF_WORD_SIZE == 64
 374                 COPYOUT(v, &md64, sizeof(md64));
 375                 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md64, sizeof(md64));
 376                 if (error != 0)
 377                         return (error);
 378                 md.md_version = md64.md_version;
 379                 md.md_type = md64.md_type;
 380                 md.md_cval = (const char *)(uintptr_t)md64.md_cval;
 381                 md.md_data = (void *)(uintptr_t)md64.md_data;
 382 #else
 383                 COPYOUT(v, &md, sizeof(md));
 384                 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md, sizeof(md));
 385                 if (error != 0)
 386                         return (error);
 387 #endif
 388                 p += sizeof(Elf_Addr);
 389                 switch(md.md_type) {
 390                 case MDT_DEPEND:
 391                         s = strdupout((vm_offset_t)md.md_cval);
 392                         minfolen = sizeof(*mdepend) + strlen(s) + 1;
 393                         mdepend = malloc(minfolen);
 394                         if (mdepend == NULL)
 395                                 return ENOMEM;
 396                         COPYOUT((vm_offset_t)md.md_data, mdepend,
 397                             sizeof(*mdepend));
 398                         strcpy((char*)(mdepend + 1), s);
 399                         free(s);
 400                         file_addmetadata(fp, MODINFOMD_DEPLIST, minfolen,
 401                             mdepend);
 402                         free(mdepend);
 403                         break;
 404                 case MDT_VERSION:
 405                         s = strdupout((vm_offset_t)md.md_cval);
 406                         COPYOUT((vm_offset_t)md.md_data, &mver, sizeof(mver));
 407                         file_addmodule(fp, s, mver.mv_version, NULL);
 408                         free(s);
 409                         modcnt++;
 410                         break;
 411                 case MDT_MODULE:
 412                 case MDT_PNP_INFO:
 413                         break;
 414                 default:
 415                         printf("unknown type %d\n", md.md_type);
 416                         break;
 417                 }
 418         }
 419         return 0;
 420 }
 421
 422 static int
 423 __elfN(obj_lookup_set)(struct preloaded_file *fp __unused, elf_file_t ef,
 424     const char* name, Elf_Addr *startp, Elf_Addr *stopp, int *countp)
 425 {
 426         Elf_Ehdr *hdr;
 427         Elf_Shdr *shdr;
 428         char *p;
 429         vm_offset_t shstrtab;
 430         int i;
 431
 432         hdr = &ef->hdr;
 433         shdr = ef->e_shdr;
 434         shstrtab = shdr[ef->shstrindex].sh_addr;
 435
 436         for (i = 0; i < hdr->e_shnum; i++) {
 437                 if (shdr[i].sh_type != SHT_PROGBITS)
 438                         continue;
 439                 if (shdr[i].sh_name == 0)
 440                         continue;
 441                 p = strdupout(shstrtab + shdr[i].sh_name);
 442                 if (strncmp(p, "set_", 4) == 0 && strcmp(p + 4, name) == 0) {
 443                         *startp = shdr[i].sh_addr;
 444                         *stopp = shdr[i].sh_addr +  shdr[i].sh_size;
 445                         *countp = (*stopp - *startp) / sizeof(Elf_Addr);
 446                         free(p);
 447                         return (0);
 448                 }
 449                 free(p);
 450         }
 451
 452         return (ESRCH);
 453 }
 454
 455 /*
 456  * Apply any intra-module relocations to the value. p is the load address
 457  * of the value and val/len is the value to be modified. This does NOT modify
 458  * the image in-place, because this is done by kern_linker later on.
 459  */
 460 static int
 461 __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, Elf_Addr p,
 462     void *val, size_t len)
 463 {
 464         Elf_Ehdr *hdr;
 465         Elf_Shdr *shdr;
 466         Elf_Addr off = p;
 467         Elf_Addr base;
 468         Elf_Rela a, *abase;
 469         Elf_Rel r, *rbase;
 470         int error, i, j, nrel, nrela;
 471
 472         (void)mp;
 473         hdr = &ef->hdr;
 474         shdr = ef->e_shdr;
 475
 476         for (i = 0; i < hdr->e_shnum; i++) {
 477                 if (shdr[i].sh_type != SHT_RELA && shdr[i].sh_type != SHT_REL)
 478                         continue;
 479                 base = shdr[shdr[i].sh_info].sh_addr;
 480                 if (base == 0 || shdr[i].sh_addr == 0)
 481                         continue;
 482                 if (off < base || off + len > base +
 483                     shdr[shdr[i].sh_info].sh_size)
 484                         continue;
 485
 486                 switch (shdr[i].sh_type) {
 487                 case SHT_RELA:
 488                         abase = (Elf_Rela *)(intptr_t)shdr[i].sh_addr;
 489
 490                         nrela = shdr[i].sh_size / sizeof(Elf_Rela);
 491                         for (j = 0; j < nrela; j++) {
 492                                 COPYOUT(abase + j, &a, sizeof(a));
 493
 494                                 error = __elfN(reloc)(ef, __elfN(obj_symaddr),
 495                                     &a, ELF_RELOC_RELA, base, off, val, len);
 496                                 if (error != 0)
 497                                         return (error);
 498                         }
 499                         break;
 500                 case SHT_REL:
 501                         rbase = (Elf_Rel *)(intptr_t)shdr[i].sh_addr;
 502
 503                         nrel = shdr[i].sh_size / sizeof(Elf_Rel);
 504                         for (j = 0; j < nrel; j++) {
 505                                 COPYOUT(rbase + j, &r, sizeof(r));
 506
 507                                 error = __elfN(reloc)(ef, __elfN(obj_symaddr),
 508                                     &r, ELF_RELOC_REL, base, off, val, len);
 509                                 if (error != 0)
 510                                         return (error);
 511                         }
 512                         break;
 513                 }
 514         }
 515         return (0);
 516 }
 517
 518 /* Look up the address of a specified symbol. */
 519 static Elf_Addr
 520 __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx)
 521 {
 522         Elf_Sym sym;
 523         Elf_Addr base;
 524
 525         if (symidx >= ef->e_shdr[ef->symtabindex].sh_size / sizeof(Elf_Sym))
 526                 return (0);
 527         COPYOUT(ef->e_shdr[ef->symtabindex].sh_addr + symidx * sizeof(Elf_Sym),
 528             &sym, sizeof(sym));
 529         if (sym.st_shndx == SHN_UNDEF || sym.st_shndx >= ef->hdr.e_shnum)
 530                 return (0);
 531         base = ef->e_shdr[sym.st_shndx].sh_addr;
 532         if (base == 0)
 533                 return (0);
 534         return (base + sym.st_value);
 535 }