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| 1 | +#include <sys/types.h> |
| 2 | +#include <sys/mman.h> |
| 3 | +#include <sys/stat.h> |
| 4 | +#include <fcntl.h> |
| 5 | +#include <stdio.h> |
| 6 | +#include <stdlib.h> |
| 7 | +#include <stdbool.h> |
| 8 | +#include <string.h> |
| 9 | +#include <unistd.h> |
| 10 | +#include <errno.h> |
| 11 | + |
| 12 | +#include "elf-parse.h" |
| 13 | + |
| 14 | +struct elf_funcs elf_parser; |
| 15 | + |
| 16 | +/* |
| 17 | + * Get the whole file as a programming convenience in order to avoid |
| 18 | + * malloc+lseek+read+free of many pieces. If successful, then mmap |
| 19 | + * avoids copying unused pieces; else just read the whole file. |
| 20 | + * Open for both read and write. |
| 21 | + */ |
| 22 | +static void *map_file(char const *fname, size_t *size) |
| 23 | +{ |
| 24 | + int fd; |
| 25 | + struct stat sb; |
| 26 | + void *addr = NULL; |
| 27 | + |
| 28 | + fd = open(fname, O_RDWR); |
| 29 | + if (fd < 0) { |
| 30 | + perror(fname); |
| 31 | + return NULL; |
| 32 | + } |
| 33 | + if (fstat(fd, &sb) < 0) { |
| 34 | + perror(fname); |
| 35 | + goto out; |
| 36 | + } |
| 37 | + if (!S_ISREG(sb.st_mode)) { |
| 38 | + fprintf(stderr, "not a regular file: %s\n", fname); |
| 39 | + goto out; |
| 40 | + } |
| 41 | + |
| 42 | + addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); |
| 43 | + if (addr == MAP_FAILED) { |
| 44 | + fprintf(stderr, "Could not mmap file: %s\n", fname); |
| 45 | + goto out; |
| 46 | + } |
| 47 | + |
| 48 | + *size = sb.st_size; |
| 49 | + |
| 50 | +out: |
| 51 | + close(fd); |
| 52 | + return addr; |
| 53 | +} |
| 54 | + |
| 55 | +static int elf_parse(const char *fname, void *addr, uint32_t types) |
| 56 | +{ |
| 57 | + Elf_Ehdr *ehdr = addr; |
| 58 | + uint16_t type; |
| 59 | + |
| 60 | + switch (ehdr->e32.e_ident[EI_DATA]) { |
| 61 | + case ELFDATA2LSB: |
| 62 | + elf_parser.r = rle; |
| 63 | + elf_parser.r2 = r2le; |
| 64 | + elf_parser.r8 = r8le; |
| 65 | + elf_parser.w = wle; |
| 66 | + elf_parser.w8 = w8le; |
| 67 | + break; |
| 68 | + case ELFDATA2MSB: |
| 69 | + elf_parser.r = rbe; |
| 70 | + elf_parser.r2 = r2be; |
| 71 | + elf_parser.r8 = r8be; |
| 72 | + elf_parser.w = wbe; |
| 73 | + elf_parser.w8 = w8be; |
| 74 | + break; |
| 75 | + default: |
| 76 | + fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", |
| 77 | + ehdr->e32.e_ident[EI_DATA], fname); |
| 78 | + return -1; |
| 79 | + } |
| 80 | + |
| 81 | + if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 || |
| 82 | + ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) { |
| 83 | + fprintf(stderr, "unrecognized ELF file %s\n", fname); |
| 84 | + return -1; |
| 85 | + } |
| 86 | + |
| 87 | + type = elf_parser.r2(&ehdr->e32.e_type); |
| 88 | + if (!((1 << type) & types)) { |
| 89 | + fprintf(stderr, "Invalid ELF type file %s\n", fname); |
| 90 | + return -1; |
| 91 | + } |
| 92 | + |
| 93 | + switch (ehdr->e32.e_ident[EI_CLASS]) { |
| 94 | + case ELFCLASS32: { |
| 95 | + elf_parser.ehdr_shoff = ehdr32_shoff; |
| 96 | + elf_parser.ehdr_shentsize = ehdr32_shentsize; |
| 97 | + elf_parser.ehdr_shstrndx = ehdr32_shstrndx; |
| 98 | + elf_parser.ehdr_shnum = ehdr32_shnum; |
| 99 | + elf_parser.shdr_addr = shdr32_addr; |
| 100 | + elf_parser.shdr_offset = shdr32_offset; |
| 101 | + elf_parser.shdr_link = shdr32_link; |
| 102 | + elf_parser.shdr_size = shdr32_size; |
| 103 | + elf_parser.shdr_name = shdr32_name; |
| 104 | + elf_parser.shdr_type = shdr32_type; |
| 105 | + elf_parser.shdr_entsize = shdr32_entsize; |
| 106 | + elf_parser.sym_type = sym32_type; |
| 107 | + elf_parser.sym_name = sym32_name; |
| 108 | + elf_parser.sym_value = sym32_value; |
| 109 | + elf_parser.sym_shndx = sym32_shndx; |
| 110 | + elf_parser.rela_offset = rela32_offset; |
| 111 | + elf_parser.rela_info = rela32_info; |
| 112 | + elf_parser.rela_addend = rela32_addend; |
| 113 | + elf_parser.rela_write_addend = rela32_write_addend; |
| 114 | + |
| 115 | + if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) || |
| 116 | + elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) { |
| 117 | + fprintf(stderr, |
| 118 | + "unrecognized ET_EXEC/ET_DYN file: %s\n", fname); |
| 119 | + return -1; |
| 120 | + } |
| 121 | + |
| 122 | + } |
| 123 | + break; |
| 124 | + case ELFCLASS64: { |
| 125 | + elf_parser.ehdr_shoff = ehdr64_shoff; |
| 126 | + elf_parser.ehdr_shentsize = ehdr64_shentsize; |
| 127 | + elf_parser.ehdr_shstrndx = ehdr64_shstrndx; |
| 128 | + elf_parser.ehdr_shnum = ehdr64_shnum; |
| 129 | + elf_parser.shdr_addr = shdr64_addr; |
| 130 | + elf_parser.shdr_offset = shdr64_offset; |
| 131 | + elf_parser.shdr_link = shdr64_link; |
| 132 | + elf_parser.shdr_size = shdr64_size; |
| 133 | + elf_parser.shdr_name = shdr64_name; |
| 134 | + elf_parser.shdr_type = shdr64_type; |
| 135 | + elf_parser.shdr_entsize = shdr64_entsize; |
| 136 | + elf_parser.sym_type = sym64_type; |
| 137 | + elf_parser.sym_name = sym64_name; |
| 138 | + elf_parser.sym_value = sym64_value; |
| 139 | + elf_parser.sym_shndx = sym64_shndx; |
| 140 | + elf_parser.rela_offset = rela64_offset; |
| 141 | + elf_parser.rela_info = rela64_info; |
| 142 | + elf_parser.rela_addend = rela64_addend; |
| 143 | + elf_parser.rela_write_addend = rela64_write_addend; |
| 144 | + |
| 145 | + if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) || |
| 146 | + elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) { |
| 147 | + fprintf(stderr, |
| 148 | + "unrecognized ET_EXEC/ET_DYN file: %s\n", |
| 149 | + fname); |
| 150 | + return -1; |
| 151 | + } |
| 152 | + |
| 153 | + } |
| 154 | + break; |
| 155 | + default: |
| 156 | + fprintf(stderr, "unrecognized ELF class %d %s\n", |
| 157 | + ehdr->e32.e_ident[EI_CLASS], fname); |
| 158 | + return -1; |
| 159 | + } |
| 160 | + return 0; |
| 161 | +} |
| 162 | + |
| 163 | +int elf_map_machine(void *addr) |
| 164 | +{ |
| 165 | + Elf_Ehdr *ehdr = addr; |
| 166 | + |
| 167 | + return elf_parser.r2(&ehdr->e32.e_machine); |
| 168 | +} |
| 169 | + |
| 170 | +int elf_map_long_size(void *addr) |
| 171 | +{ |
| 172 | + Elf_Ehdr *ehdr = addr; |
| 173 | + |
| 174 | + return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; |
| 175 | +} |
| 176 | + |
| 177 | +void *elf_map(char const *fname, size_t *size, uint32_t types) |
| 178 | +{ |
| 179 | + void *addr; |
| 180 | + int ret; |
| 181 | + |
| 182 | + addr = map_file(fname, size); |
| 183 | + if (!addr) |
| 184 | + return NULL; |
| 185 | + |
| 186 | + ret = elf_parse(fname, addr, types); |
| 187 | + if (ret < 0) { |
| 188 | + elf_unmap(addr, *size); |
| 189 | + return NULL; |
| 190 | + } |
| 191 | + |
| 192 | + return addr; |
| 193 | +} |
| 194 | + |
| 195 | +void elf_unmap(void *addr, size_t size) |
| 196 | +{ |
| 197 | + munmap(addr, size); |
| 198 | +} |
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