1 /* 2 * ELF payload decoding support. 3 * 4 * Copyright (C) 2022, 2023, 2024 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #include <l4/util/elf.h> 23 24 #include "elf.h" 25 26 27 28 /* Program segment construction for 32- or 64-bit variants. */ 29 30 template <typename PROGRAM_HEADER> 31 ProgramSegmentVariant<PROGRAM_HEADER>::ProgramSegmentVariant(PROGRAM_HEADER *header) 32 : _header(header) 33 { 34 init(); 35 } 36 37 template <typename PROGRAM_HEADER> 38 bool ProgramSegmentVariant<PROGRAM_HEADER>::loadable() 39 { 40 return _header->p_type == PT_LOAD; 41 } 42 43 template <typename PROGRAM_HEADER> 44 offset_t ProgramSegmentVariant<PROGRAM_HEADER>::file_contents() 45 { 46 return _header->p_filesz; 47 } 48 49 template <typename PROGRAM_HEADER> 50 offset_t ProgramSegmentVariant<PROGRAM_HEADER>::file_offset() 51 { 52 return _header->p_offset; 53 } 54 55 template <typename PROGRAM_HEADER> 56 l4_addr_t ProgramSegmentVariant<PROGRAM_HEADER>::region_address() 57 { 58 return _header->p_vaddr; 59 } 60 61 template <typename PROGRAM_HEADER> 62 offset_t ProgramSegmentVariant<PROGRAM_HEADER>::region_size() 63 { 64 return _header->p_memsz; 65 } 66 67 template <typename PROGRAM_HEADER> 68 rm_flags_t ProgramSegmentVariant<PROGRAM_HEADER>::region_flags() 69 { 70 rm_flags_t flags = 0; 71 72 if (_header->p_flags & PF_R) 73 flags |= L4RE_RM_F_R; 74 if (_header->p_flags & PF_W) 75 flags |= L4RE_RM_F_W; 76 if (_header->p_flags & PF_X) 77 flags |= L4RE_RM_F_X; 78 79 return flags; 80 } 81 82 83 84 /* Generic payload destruction. */ 85 86 Payload::~Payload() 87 { 88 } 89 90 unsigned int Payload::segments() 91 { 92 return 0; 93 } 94 95 96 97 /* ELF payload construction for 32- or 64-bit variants. */ 98 99 template <typename HEADER, typename PROGRAM_HEADER> 100 PayloadVariant<HEADER, PROGRAM_HEADER>::PayloadVariant(HEADER *header) 101 : _header(header) 102 { 103 /* Record the number of segments since various methods depend on it, but the 104 header data may be unavailable when it is used, upon destruction, for 105 example. */ 106 107 _nsegments = _header->e_phnum; 108 } 109 110 /* Specific payload destruction. */ 111 112 template <typename HEADER, typename PROGRAM_HEADER> 113 PayloadVariant<HEADER, PROGRAM_HEADER>::~PayloadVariant() 114 { 115 if (_segments != NULL) 116 { 117 for (unsigned int i = 0; i < segments(); i++) 118 delete _segments[i]; 119 120 delete _segments; 121 } 122 } 123 124 template <typename HEADER, typename PROGRAM_HEADER> 125 l4_addr_t PayloadVariant<HEADER, PROGRAM_HEADER>::entry_point() 126 { 127 return _header->e_entry; 128 } 129 130 template <typename HEADER, typename PROGRAM_HEADER> 131 offset_t PayloadVariant<HEADER, PROGRAM_HEADER>::header_extent() 132 { 133 return sizeof(HEADER); 134 } 135 136 template <typename HEADER, typename PROGRAM_HEADER> 137 offset_t PayloadVariant<HEADER, PROGRAM_HEADER>::program_header_extent() 138 { 139 return _header->e_phoff + _header->e_phentsize * _header->e_phnum; 140 } 141 142 template <typename HEADER, typename PROGRAM_HEADER> 143 unsigned int PayloadVariant<HEADER, PROGRAM_HEADER>::segments() 144 { 145 return _nsegments; 146 } 147 148 template <typename HEADER, typename PROGRAM_HEADER> 149 Segment *PayloadVariant<HEADER, PROGRAM_HEADER>::segment(unsigned int i) 150 { 151 if (i >= segments()) 152 return NULL; 153 154 if (_segments == NULL) 155 { 156 _segments = new Segment *[segments()]; 157 158 for (unsigned int j = 0; j < segments(); j++) 159 _segments[j] = NULL; 160 } 161 162 Segment *segment = _segments[i]; 163 164 if (segment == NULL) 165 { 166 segment = new ProgramSegmentVariant<PROGRAM_HEADER>( 167 (PROGRAM_HEADER *) ((char *) _header + _header->e_phoff + 168 _header->e_phentsize * i)); 169 _segments[i] = segment; 170 } 171 172 return segment; 173 } 174 175 176 177 /* Return the appropriate payload object. */ 178 179 Payload *exec_open_payload(char *buf) 180 { 181 switch (buf[EI_CLASS]) 182 { 183 case (char) 1: 184 return new PayloadVariant<Elf32_Ehdr, Elf32_Phdr>((Elf32_Ehdr *) buf); 185 case (char) 2: 186 return new PayloadVariant<Elf64_Ehdr, Elf64_Phdr>((Elf64_Ehdr *) buf); 187 default: 188 return NULL; 189 } 190 } 191 192 /* vim: tabstop=2 expandtab shiftwidth=2 193 */