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IABSD.fr/src/lib/libelf/libelf_ehdr.c
jsg
- lib/libelf/libelf_ehdr.c
-
/*- * Copyright (c) 2006,2008 Joseph Koshy * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <assert.h> #include <gelf.h> #include <libelf.h> #include <stdlib.h> #include "_libelf.h" ELFTC_VCSID("$Id: libelf_ehdr.c,v 1.3 2020/05/18 06:46:23 jsg Exp $"); /* * Retrieve counts for sections, phdrs and the section string table index * from section header #0 of the ELF object. */ static int _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum, uint16_t strndx) { size_t fsz; Elf_Scn *scn; uint32_t shtype; _libelf_translator_function *xlator; assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); assert(fsz > 0); if (shoff + fsz < shoff) { /* Numeric overflow. */ LIBELF_SET_ERROR(HEADER, 0); return (0); } if ((uint64_t) e->e_rawsize < shoff + fsz) { LIBELF_SET_ERROR(HEADER, 0); return (0); } if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) return (0); xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec, _libelf_elfmachine(e)); (*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr), (unsigned char *) e->e_rawfile + shoff, (size_t) 1, e->e_byteorder != LIBELF_PRIVATE(byteorder)); #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ scn->s_shdr.s_shdr64.M) if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { LIBELF_SET_ERROR(SECTION, 0); return (0); } e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size); e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : GET_SHDR_MEMBER(sh_info); e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : GET_SHDR_MEMBER(sh_link); #undef GET_SHDR_MEMBER return (1); } #define EHDR_INIT(E,SZ) do { \ Elf##SZ##_Ehdr *eh = (E); \ eh->e_ident[EI_MAG0] = ELFMAG0; \ eh->e_ident[EI_MAG1] = ELFMAG1; \ eh->e_ident[EI_MAG2] = ELFMAG2; \ eh->e_ident[EI_MAG3] = ELFMAG3; \ eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ eh->e_ident[EI_DATA] = ELFDATANONE; \ eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \ eh->e_machine = EM_NONE; \ eh->e_type = ELF_K_NONE; \ eh->e_version = LIBELF_PRIVATE(version); \ } while (0) void * _libelf_ehdr(Elf *e, int ec, int allocate) { void *ehdr; size_t fsz, msz; uint16_t phnum, shnum, strndx; uint64_t shoff; int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, size_t _c, int _swap); assert(ec == ELFCLASS32 || ec == ELFCLASS64); if (e == NULL || e->e_kind != ELF_K_ELF) { LIBELF_SET_ERROR(ARGUMENT, 0); return (NULL); } if (e->e_class != ELFCLASSNONE && e->e_class != ec) { LIBELF_SET_ERROR(CLASS, 0); return (NULL); } if (e->e_version != EV_CURRENT) { LIBELF_SET_ERROR(VERSION, 0); return (NULL); } if (e->e_class == ELFCLASSNONE) e->e_class = ec; if (ec == ELFCLASS32) ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; else ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; if (ehdr != NULL) /* already have a translated ehdr */ return (ehdr); fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); assert(fsz > 0); if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < (off_t) fsz) { LIBELF_SET_ERROR(HEADER, 0); return (NULL); } if ((msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT)) == 0) return (NULL); if ((ehdr = calloc((size_t) 1, msz)) == NULL) { LIBELF_SET_ERROR(RESOURCE, 0); return (NULL); } if (ec == ELFCLASS32) { e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; EHDR_INIT(ehdr,32); } else { e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; EHDR_INIT(ehdr,64); } if (allocate) e->e_flags |= ELF_F_DIRTY; if (e->e_cmd == ELF_C_WRITE) return (ehdr); xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec, _libelf_elfmachine(e)); (*xlator)((unsigned char*) ehdr, msz, e->e_rawfile, (size_t) 1, e->e_byteorder != LIBELF_PRIVATE(byteorder)); if (ec == ELFCLASS32) { phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; } else { phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; } if (shnum >= SHN_LORESERVE || (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || strndx == SHN_XINDEX))) { LIBELF_SET_ERROR(HEADER, 0); return (NULL); } /* * If extended numbering is being used, read the correct * number of sections and program header entries. */ if ((shnum == 0 && shoff != 0) || phnum == PN_XNUM || strndx == SHN_XINDEX) { if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) return (NULL); } else { /* not using extended numbering */ e->e_u.e_elf.e_nphdr = phnum; e->e_u.e_elf.e_nscn = shnum; e->e_u.e_elf.e_strndx = strndx; } return (ehdr); }