/* Return section header. Copyright (C) 1998-2002, 2005, 2007, 2009, 2012, 2014, 2015 Red Hat, Inc. This file is part of elfutils. Written by Ulrich Drepper , 1998. This file is free software; you can redistribute it and/or modify it under the terms of either * the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version or * the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version or both in parallel, as here. elfutils is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received copies of the GNU General Public License and the GNU Lesser General Public License along with this program. If not, see . */ #ifdef HAVE_CONFIG_H # include #endif #include #include #include #include #include #include "libelfP.h" #include "common.h" #ifndef LIBELFBITS # define LIBELFBITS 32 #endif static ElfW2(LIBELFBITS,Shdr) * load_shdr_wrlock (Elf_Scn *scn) { ElfW2(LIBELFBITS,Shdr) *result; /* Read the section header table. */ Elf *elf = scn->elf; ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr; /* Try again, maybe the data is there now. */ result = scn->shdr.ELFW(e,LIBELFBITS); if (result != NULL) goto out; size_t shnum; if (__elf_getshdrnum_rdlock (elf, &shnum) != 0 || shnum > SIZE_MAX / sizeof (ElfW2(LIBELFBITS,Shdr))) goto out; size_t size = shnum * sizeof (ElfW2(LIBELFBITS,Shdr)); /* Allocate memory for the section headers. We know the number of entries from the ELF header. */ ElfW2(LIBELFBITS,Shdr) *shdr = elf->state.ELFW(elf,LIBELFBITS).shdr = (ElfW2(LIBELFBITS,Shdr) *) malloc (size); if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL) { __libelf_seterrno (ELF_E_NOMEM); goto out; } elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 1; if (elf->map_address != NULL) { /* First see whether the information in the ELF header is valid and it does not ask for too much. */ if (unlikely (ehdr->e_shoff >= elf->maximum_size) || unlikely (elf->maximum_size - ehdr->e_shoff < size)) { /* Something is wrong. */ __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER); goto free_and_out; } ElfW2(LIBELFBITS,Shdr) *notcvt; /* All the data is already mapped. If we could use it directly this would already have happened. Unless we allocated the memory ourselves and the ELF_F_MALLOCED flag is set. */ void *file_shdr = ((char *) elf->map_address + elf->start_offset + ehdr->e_shoff); assert ((elf->flags & ELF_F_MALLOCED) || ehdr->e_ident[EI_DATA] != MY_ELFDATA || elf->cmd == ELF_C_READ_MMAP || (! ALLOW_UNALIGNED && ((uintptr_t) file_shdr & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0)); /* Now copy the data and at the same time convert the byte order. */ if (ehdr->e_ident[EI_DATA] == MY_ELFDATA) { assert ((elf->flags & ELF_F_MALLOCED) || elf->cmd == ELF_C_READ_MMAP || ! ALLOW_UNALIGNED); memcpy (shdr, file_shdr, size); } else { bool copy = ! (ALLOW_UNALIGNED || ((uintptr_t) file_shdr & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) == 0); if (! copy) notcvt = (ElfW2(LIBELFBITS,Shdr) *) ((char *) elf->map_address + elf->start_offset + ehdr->e_shoff); else { notcvt = (ElfW2(LIBELFBITS,Shdr) *) malloc (size); if (unlikely (notcvt == NULL)) { __libelf_seterrno (ELF_E_NOMEM); goto out; } memcpy (notcvt, ((char *) elf->map_address + elf->start_offset + ehdr->e_shoff), size); } for (size_t cnt = 0; cnt < shnum; ++cnt) { CONVERT_TO (shdr[cnt].sh_name, notcvt[cnt].sh_name); CONVERT_TO (shdr[cnt].sh_type, notcvt[cnt].sh_type); CONVERT_TO (shdr[cnt].sh_flags, notcvt[cnt].sh_flags); CONVERT_TO (shdr[cnt].sh_addr, notcvt[cnt].sh_addr); CONVERT_TO (shdr[cnt].sh_offset, notcvt[cnt].sh_offset); CONVERT_TO (shdr[cnt].sh_size, notcvt[cnt].sh_size); CONVERT_TO (shdr[cnt].sh_link, notcvt[cnt].sh_link); CONVERT_TO (shdr[cnt].sh_info, notcvt[cnt].sh_info); CONVERT_TO (shdr[cnt].sh_addralign, notcvt[cnt].sh_addralign); CONVERT_TO (shdr[cnt].sh_entsize, notcvt[cnt].sh_entsize); /* If this is a section with an extended index add a reference in the section which uses the extended index. */ if (shdr[cnt].sh_type == SHT_SYMTAB_SHNDX && shdr[cnt].sh_link < shnum) elf->state.ELFW(elf,LIBELFBITS).scns.data[shdr[cnt].sh_link].shndx_index = cnt; /* Set the own shndx_index field in case it has not yet been set. */ if (elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index == 0) elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index = -1; } if (copy) free (notcvt); } } else if (likely (elf->fildes != -1)) { /* Read the header. */ ssize_t n = pread_retry (elf->fildes, elf->state.ELFW(elf,LIBELFBITS).shdr, size, elf->start_offset + ehdr->e_shoff); if (unlikely ((size_t) n != size)) { /* Severe problems. We cannot read the data. */ __libelf_seterrno (ELF_E_READ_ERROR); goto free_and_out; } /* If the byte order of the file is not the same as the one of the host convert the data now. */ if (ehdr->e_ident[EI_DATA] != MY_ELFDATA) for (size_t cnt = 0; cnt < shnum; ++cnt) { CONVERT (shdr[cnt].sh_name); CONVERT (shdr[cnt].sh_type); CONVERT (shdr[cnt].sh_flags); CONVERT (shdr[cnt].sh_addr); CONVERT (shdr[cnt].sh_offset); CONVERT (shdr[cnt].sh_size); CONVERT (shdr[cnt].sh_link); CONVERT (shdr[cnt].sh_info); CONVERT (shdr[cnt].sh_addralign); CONVERT (shdr[cnt].sh_entsize); } } else { /* The file descriptor was already enabled and not all data was read. Undo the allocation. */ __libelf_seterrno (ELF_E_FD_DISABLED); free_and_out: free (shdr); elf->state.ELFW(elf,LIBELFBITS).shdr = NULL; elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 0; goto out; } /* Set the pointers in the `scn's. */ for (size_t cnt = 0; cnt < shnum; ++cnt) elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shdr.ELFW(e,LIBELFBITS) = &elf->state.ELFW(elf,LIBELFBITS).shdr[cnt]; result = scn->shdr.ELFW(e,LIBELFBITS); assert (result != NULL); out: return result; } static bool scn_valid (Elf_Scn *scn) { if (scn == NULL) return false; if (unlikely (scn->elf->state.elf.ehdr == NULL)) { __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR); return false; } if (unlikely (scn->elf->class != ELFW(ELFCLASS,LIBELFBITS))) { __libelf_seterrno (ELF_E_INVALID_CLASS); return false; } return true; } ElfW2(LIBELFBITS,Shdr) * internal_function __elfw2(LIBELFBITS,getshdr_rdlock) (Elf_Scn *scn) { ElfW2(LIBELFBITS,Shdr) *result; if (!scn_valid (scn)) return NULL; result = scn->shdr.ELFW(e,LIBELFBITS); if (result == NULL) { rwlock_unlock (scn->elf->lock); rwlock_wrlock (scn->elf->lock); result = scn->shdr.ELFW(e,LIBELFBITS); if (result == NULL) result = load_shdr_wrlock (scn); } return result; } ElfW2(LIBELFBITS,Shdr) * internal_function __elfw2(LIBELFBITS,getshdr_wrlock) (Elf_Scn *scn) { ElfW2(LIBELFBITS,Shdr) *result; if (!scn_valid (scn)) return NULL; result = scn->shdr.ELFW(e,LIBELFBITS); if (result == NULL) result = load_shdr_wrlock (scn); return result; } ElfW2(LIBELFBITS,Shdr) * elfw2(LIBELFBITS,getshdr) (Elf_Scn *scn) { ElfW2(LIBELFBITS,Shdr) *result; if (!scn_valid (scn)) return NULL; rwlock_rdlock (scn->elf->lock); result = __elfw2(LIBELFBITS,getshdr_rdlock) (scn); rwlock_unlock (scn->elf->lock); return result; }