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111 lines
4.6 KiB
111 lines
4.6 KiB
/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved. |
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* Use of this source code is governed by a BSD-style license that can be |
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* found in the LICENSE file. |
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*/ |
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#include "elfparse.h" |
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int is_elf_magic (const uint8_t *buf) |
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{ |
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return (buf[EI_MAG0] == ELFMAG0) && |
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(buf[EI_MAG1] == ELFMAG1) && |
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(buf[EI_MAG2] == ELFMAG2) && |
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(buf[EI_MAG3] == ELFMAG3); |
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} |
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#define parseElftemplate(bit) \ |
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ElfType parseElf ## bit(FILE *elf_file, uint8_t *pHead, int little_endian) \ |
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{ \ |
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ElfType ret = ELFSTATIC; \ |
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Minijail_Elf ## bit ## _Ehdr *pHeader = NULL; \ |
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Minijail_Elf ## bit ## _Phdr pheader = { 0 }; \ |
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uint32_t i = 0; \ |
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\ |
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if (!elf_file || !pHead) \ |
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return ELFERROR; \ |
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\ |
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pHeader = (Minijail_Elf ## bit ## _Ehdr *)pHead; \ |
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if (little_endian) { \ |
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pHeader->e_phoff = le ## bit ## toh(pHeader->e_phoff); \ |
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pHeader->e_phentsize = le16toh(pHeader->e_phentsize); \ |
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pHeader->e_phnum = le16toh(pHeader->e_phnum); \ |
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} else { \ |
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pHeader->e_phoff = be ## bit ## toh(pHeader->e_phoff); \ |
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pHeader->e_phentsize = be16toh(pHeader->e_phentsize); \ |
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pHeader->e_phnum = be16toh(pHeader->e_phnum); \ |
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} \ |
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if (pHeader->e_phentsize != sizeof(Minijail_Elf ## bit ## _Phdr)) \ |
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return ELFERROR; \ |
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\ |
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if (fseek(elf_file, pHeader->e_phoff, SEEK_SET) != 0) \ |
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return ELFERROR; \ |
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\ |
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for (i = 0; i < pHeader->e_phnum; i++) { \ |
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if (fread(&pheader, sizeof(pheader), 1, elf_file) == 1) { \ |
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if (pheader.p_type == PT_INTERP) { \ |
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ret = ELFDYNAMIC; \ |
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break; \ |
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} \ |
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} else { \ |
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ret = ELFERROR; \ |
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break; \ |
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} \ |
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} \ |
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return ret; \ |
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} |
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parseElftemplate(64) |
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parseElftemplate(32) |
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/* Public function to determine the linkage of an ELF. */ |
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ElfType get_elf_linkage(const char *path) |
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{ |
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ElfType ret = ELFERROR; |
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FILE *elf_file = NULL; |
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uint8_t pHeader[HEADERSIZE] = ""; |
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elf_file = fopen(path, "r"); |
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if (elf_file) { |
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if (fread(pHeader, 1, HEADERSIZE, elf_file) == HEADERSIZE) { |
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if (is_elf_magic(pHeader)) { |
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if ((pHeader[EI_DATA] == ELFDATA2LSB) && |
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(pHeader[EI_CLASS] == ELFCLASS64)) { |
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/* 64-bit little endian. */ |
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ret = parseElf64(elf_file, pHeader, 1); |
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} else if ((pHeader[EI_DATA] == ELFDATA2MSB) && |
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(pHeader[EI_CLASS] == ELFCLASS64)) { |
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/* 64-bit big endian. */ |
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ret = parseElf64(elf_file, pHeader, 0); |
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} else if ((pHeader[EI_DATA] == ELFDATA2LSB) && |
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(pHeader[EI_CLASS] == ELFCLASS32)) { |
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/* 32-bit little endian. */ |
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ret = parseElf32(elf_file, pHeader, 1); |
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} else if ((pHeader[EI_DATA] == ELFDATA2MSB) && |
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(pHeader[EI_CLASS] == ELFCLASS32)) { |
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/* 32-bit big endian. */ |
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ret = parseElf32(elf_file, pHeader, 0); |
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} |
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} else { |
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/* |
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* The binary is not an ELF. We assume it's a |
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* script. We should parse the #! line and |
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* check the interpreter to guard against |
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* static interpreters escaping the sandbox. |
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* As Minijail is only called from the rootfs |
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* it was deemed not necessary to check this. |
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* So we will just let execve(2) decide if this |
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* is valid. |
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*/ |
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ret = ELFDYNAMIC; |
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} |
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} else { |
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/* |
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* The file is smaller than |HEADERSIZE| bytes. |
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* We assume it's a short script. See above for |
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* reasoning on scripts. |
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*/ |
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ret = ELFDYNAMIC; |
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} |
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fclose(elf_file); |
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} |
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return ret; |
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}
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