| /* |
| * Copyright (c) 2014 The Chromium OS Authors. All rights reserved. |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "elfparse.h" |
| |
| int is_elf_magic (const uint8_t *buf) |
| { |
| return (buf[EI_MAG0] == ELFMAG0) && |
| (buf[EI_MAG1] == ELFMAG1) && |
| (buf[EI_MAG2] == ELFMAG2) && |
| (buf[EI_MAG3] == ELFMAG3); |
| } |
| |
| #define parseElftemplate(bit) \ |
| ElfType parseElf ## bit(FILE *elf_file, uint8_t *pHead, int little_endian) \ |
| { \ |
| ElfType ret = ELFSTATIC; \ |
| Minijail_Elf ## bit ## _Ehdr *pHeader = NULL; \ |
| Minijail_Elf ## bit ## _Phdr pheader = { 0 }; \ |
| uint32_t i = 0; \ |
| \ |
| if (!elf_file || !pHead) \ |
| return ELFERROR; \ |
| \ |
| pHeader = (Minijail_Elf ## bit ## _Ehdr *)pHead; \ |
| if (little_endian) { \ |
| pHeader->e_phoff = le ## bit ## toh(pHeader->e_phoff); \ |
| pHeader->e_phentsize = le16toh(pHeader->e_phentsize); \ |
| pHeader->e_phnum = le16toh(pHeader->e_phnum); \ |
| } else { \ |
| pHeader->e_phoff = be ## bit ## toh(pHeader->e_phoff); \ |
| pHeader->e_phentsize = be16toh(pHeader->e_phentsize); \ |
| pHeader->e_phnum = be16toh(pHeader->e_phnum); \ |
| } \ |
| if (pHeader->e_phentsize != sizeof(Minijail_Elf ## bit ## _Phdr)) \ |
| return ELFERROR; \ |
| \ |
| if (fseek(elf_file, pHeader->e_phoff, SEEK_SET) != 0) \ |
| return ELFERROR; \ |
| \ |
| for (i = 0; i < pHeader->e_phnum; i++) { \ |
| if (fread(&pheader, sizeof(pheader), 1, elf_file) == 1) { \ |
| if (pheader.p_type == PT_INTERP) { \ |
| ret = ELFDYNAMIC; \ |
| break; \ |
| } \ |
| } else { \ |
| ret = ELFERROR; \ |
| break; \ |
| } \ |
| } \ |
| return ret; \ |
| } |
| parseElftemplate(64) |
| parseElftemplate(32) |
| |
| /* Public function to determine the linkage of an ELF. */ |
| ElfType get_elf_linkage(const char *path) |
| { |
| ElfType ret = ELFERROR; |
| FILE *elf_file = NULL; |
| uint8_t pHeader[HEADERSIZE] = ""; |
| |
| elf_file = fopen(path, "r"); |
| if (elf_file) { |
| if (fread(pHeader, 1, HEADERSIZE, elf_file) == HEADERSIZE) { |
| if (is_elf_magic(pHeader)) { |
| if ((pHeader[EI_DATA] == ELFDATA2LSB) && |
| (pHeader[EI_CLASS] == ELFCLASS64)) { |
| /* 64 bit little endian */ |
| ret = parseElf64(elf_file, pHeader, 1); |
| } else if ((pHeader[EI_DATA] == ELFDATA2MSB) && |
| (pHeader[EI_CLASS] == ELFCLASS64)) { |
| /* 64 bit big endian */ |
| ret = parseElf64(elf_file, pHeader, 0); |
| } else if ((pHeader[EI_DATA] == ELFDATA2LSB) && |
| (pHeader[EI_CLASS] == ELFCLASS32)) { |
| /* 32 bit little endian */ |
| ret = parseElf32(elf_file, pHeader, 1); |
| } else if ((pHeader[EI_DATA] == ELFDATA2MSB) && |
| (pHeader[EI_CLASS] == ELFCLASS32)) { |
| /* 32 bit big endian */ |
| ret = parseElf32(elf_file, pHeader, 0); |
| } |
| } else { |
| /* |
| * The binary is not an ELF. We assume it's a |
| * script. We should parse the #! line and |
| * check the interpreter to guard against |
| * static interpreters escaping the sandbox. |
| * As minijail is only called from rootfs |
| * it was deemed not necessary to check this. |
| * So we will just let execve decided if this |
| * is valid. |
| */ |
| ret = ELFDYNAMIC; |
| } |
| } else { |
| /* |
| * The file is smaller than |HEADERSIZE| bytes. |
| * We assume it's a short script. See above for |
| * reasoning on scripts. |
| */ |
| ret = ELFDYNAMIC; |
| } |
| fclose(elf_file); |
| } |
| return ret; |
| } |