268 lines
7.4 KiB
C
268 lines
7.4 KiB
C
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#include "elflib.h"
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#define PRINTF __attribute__ ((format (printf, 1, 2)))
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PRINTF void fatal(const char *fmt, ...)
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{
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va_list arglist;
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fprintf(stderr, "FATAL: ");
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va_start(arglist, fmt);
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vfprintf(stderr, fmt, arglist);
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va_end(arglist);
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exit(1);
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}
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PRINTF void warn(const char *fmt, ...)
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{
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va_list arglist;
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fprintf(stderr, "WARNING: ");
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va_start(arglist, fmt);
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vfprintf(stderr, fmt, arglist);
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va_end(arglist);
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}
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PRINTF void merror(const char *fmt, ...)
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{
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va_list arglist;
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fprintf(stderr, "ERROR: ");
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va_start(arglist, fmt);
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vfprintf(stderr, fmt, arglist);
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va_end(arglist);
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}
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static void *grab_file_rw(const char *filename, unsigned long *size,
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unsigned char write)
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{
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struct stat st;
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void *map;
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int fd, open_flag, map_flag;
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if (write) {
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open_flag = O_RDWR;
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map_flag = MAP_SHARED;
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} else {
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open_flag = O_RDONLY;
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map_flag = MAP_PRIVATE;
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}
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fd = open(filename, open_flag);
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if (fd < 0 || fstat(fd, &st) != 0)
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return NULL;
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*size = st.st_size;
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map = mmap(NULL, *size, PROT_READ|PROT_WRITE, map_flag, fd, 0);
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close(fd);
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if (map == MAP_FAILED)
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return NULL;
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return map;
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}
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static void set_ksymtable(struct elf_info *info, enum ksymtab_type type,
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Elf_Ehdr *hdr, Elf_Shdr *sechdrs, unsigned int secidx,
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const char *secname)
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{
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info->ksym_tables[type].start = (struct kernel_symbol *) \
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((void *) hdr + sechdrs[secidx].sh_offset);
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info->ksym_tables[type].stop = (struct kernel_symbol *) \
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((void *) hdr + sechdrs[secidx].sh_offset + sechdrs[secidx].sh_size);
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info->ksym_tables[type].name = strdup(secname);
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info->ksym_tables[type].sec = secidx;
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}
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static int parse_elf_rw(struct elf_info *info, const char *filename,
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unsigned char write)
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{
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unsigned int i;
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Elf_Ehdr *hdr;
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Elf_Shdr *sechdrs;
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Elf_Sym *sym;
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char *lkm_suffix;
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hdr = grab_file_rw(filename, &info->size, write);
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if (!hdr) {
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perror(filename);
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exit(1);
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}
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info->hdr = hdr;
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if (info->size < sizeof(*hdr)) {
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/* file too small, assume this is an empty .o file */
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return 0;
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}
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/* Is this a valid ELF file? */
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if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
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(hdr->e_ident[EI_MAG1] != ELFMAG1) ||
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(hdr->e_ident[EI_MAG2] != ELFMAG2) ||
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(hdr->e_ident[EI_MAG3] != ELFMAG3)) {
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/* Not an ELF file - silently ignore it */
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return 0;
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}
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/* Fix endianness in ELF header */
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hdr->e_type = TO_NATIVE(hdr->e_type);
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hdr->e_machine = TO_NATIVE(hdr->e_machine);
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hdr->e_version = TO_NATIVE(hdr->e_version);
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hdr->e_entry = TO_NATIVE(hdr->e_entry);
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hdr->e_phoff = TO_NATIVE(hdr->e_phoff);
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hdr->e_shoff = TO_NATIVE(hdr->e_shoff);
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hdr->e_flags = TO_NATIVE(hdr->e_flags);
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hdr->e_ehsize = TO_NATIVE(hdr->e_ehsize);
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hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize);
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hdr->e_phnum = TO_NATIVE(hdr->e_phnum);
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hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize);
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hdr->e_shnum = TO_NATIVE(hdr->e_shnum);
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hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx);
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sechdrs = (void *)hdr + hdr->e_shoff;
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info->sechdrs = sechdrs;
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/* Check if file offset is correct */
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if (hdr->e_shoff > info->size) {
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fatal("section header offset=%lu in file '%s' is bigger than "
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"filesize=%lu\n", (unsigned long)hdr->e_shoff,
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filename, info->size);
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return 0;
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}
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/* Fix endianness in section headers */
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for (i = 0; i < hdr->e_shnum; i++) {
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sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name);
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sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type);
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sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags);
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sechdrs[i].sh_addr = TO_NATIVE(sechdrs[i].sh_addr);
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sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset);
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sechdrs[i].sh_size = TO_NATIVE(sechdrs[i].sh_size);
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sechdrs[i].sh_link = TO_NATIVE(sechdrs[i].sh_link);
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sechdrs[i].sh_info = TO_NATIVE(sechdrs[i].sh_info);
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sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign);
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sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize);
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}
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/* Find symbol tables and text section. */
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for (i = 1; i < hdr->e_shnum; i++) {
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const char *secstrings
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= (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
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const char *secname;
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int nobits = sechdrs[i].sh_type == SHT_NOBITS;
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if (!nobits && sechdrs[i].sh_offset > info->size) {
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fatal("%s is truncated. sechdrs[i].sh_offset=%lu > "
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"sizeof(*hrd)=%zu\n", filename,
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(unsigned long)sechdrs[i].sh_offset,
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sizeof(*hdr));
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return 0;
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}
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secname = secstrings + sechdrs[i].sh_name;
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if (strcmp(secname, ".text") == 0)
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info->base_addr = sechdrs[i].sh_addr -
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sechdrs[i].sh_offset;
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else if (strcmp(secname, ".modinfo") == 0) {
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if (nobits)
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fatal("%s has NOBITS .modinfo\n", filename);
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info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
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info->modinfo_len = sechdrs[i].sh_size;
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} else if (strcmp(secname, "__ksymtab") == 0)
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set_ksymtable(info, KSYMTAB, hdr, sechdrs, i, secname);
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else if (strcmp(secname, "__ksymtab_unused") == 0)
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set_ksymtable(info, KSYMTAB_UNUSED, hdr, sechdrs, i,
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secname);
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else if (strcmp(secname, "__ksymtab_gpl") == 0)
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set_ksymtable(info, KSYMTAB_GPL, hdr, sechdrs, i,
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secname);
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else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)
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set_ksymtable(info, KSYMTAB_UNUSED_GPL, hdr, sechdrs, i,
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secname);
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else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
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set_ksymtable(info, KSYMTAB_GPL_FUTURE, hdr, sechdrs, i,
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secname);
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else if (strcmp(secname, "__ksymtab_strings") == 0)
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info->kstrings = (void *)hdr + sechdrs[i].sh_offset;
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else if (strcmp(secname, "__markers_strings") == 0)
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info->markers_strings_sec = i;
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else if (strcmp(secname, ".undef.hash") == 0) {
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info->undef_hash.start = (void *)
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hdr + sechdrs[i].sh_offset;
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info->undef_hash.stop = (void *)
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hdr + sechdrs[i].sh_offset + sechdrs[i].sh_size;
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}
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if (sechdrs[i].sh_type != SHT_SYMTAB)
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continue;
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info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
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info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset
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+ sechdrs[i].sh_size;
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info->strtab = (void *)hdr +
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sechdrs[sechdrs[i].sh_link].sh_offset;
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}
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if (!info->symtab_start)
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fatal("%s has no symtab?\n", filename);
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/* Check if it is the vmlinux or lkm */
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lkm_suffix = strstr(filename, ".ko");
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if (lkm_suffix && (strlen(lkm_suffix) == 3))
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/* Likely this is a lkm */
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/*
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* ksym->name is an offset with respect to the start of the
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* __ksymtab_strings
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*/
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info->kstr_offset = (long) info->kstrings;
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else
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/*
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* In this case, ksym->name is the absolute value of the string
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* into the __ksymtab_strings
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*/
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info->kstr_offset = (long)info->hdr - (long)info->base_addr;
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/* Fix endianness in symbols */
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for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
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sym->st_shndx = TO_NATIVE(sym->st_shndx);
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sym->st_name = TO_NATIVE(sym->st_name);
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sym->st_value = TO_NATIVE(sym->st_value);
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sym->st_size = TO_NATIVE(sym->st_size);
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}
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return 1;
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}
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ksym_hash_t gnu_hash(const unsigned char *name)
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{
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ksym_hash_t h = 5381;
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unsigned char c;
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for (c = *name; c != '\0'; c = *++name)
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h = h * 33 + c;
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return h & 0xffffffff;
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}
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void *grab_file(const char *filename, unsigned long *size)
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{
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/* Read-only */
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return grab_file_rw(filename, size, 0);
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}
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void release_file(void *file, unsigned long size)
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{
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munmap(file, size);
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}
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int parse_elf(struct elf_info *info, const char *filename)
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{
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/* Read-only */
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return parse_elf_rw(info, filename, 0);
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}
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int parse_writable_elf(struct elf_info *info, const char *filename)
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{
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return parse_elf_rw(info, filename, 1);
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}
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void parse_elf_finish(struct elf_info *info)
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{
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release_file(info->hdr, info->size);
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}
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