Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 1 | /* |
| 2 | * elf header parsing. |
| 3 | * |
| 4 | * Copyright (C) 2013 Google, Inc. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License as published by |
| 8 | * the Free Software Foundation; version 2 of the License. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
Patrick Georgi | b890a12 | 2015-03-26 15:17:45 +0100 | [diff] [blame] | 17 | * Foundation, Inc. |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 18 | */ |
| 19 | |
| 20 | #include <stdio.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <string.h> |
| 23 | |
Aaron Durbin | 54ef306 | 2014-03-05 12:12:09 -0600 | [diff] [blame] | 24 | #include "elfparsing.h" |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 25 | #include "common.h" |
| 26 | #include "cbfs.h" |
| 27 | |
| 28 | /* |
| 29 | * Short form: this is complicated, but we've tried making it simple |
| 30 | * and we keep hitting problems with our ELF parsing. |
| 31 | * |
| 32 | * The ELF parsing situation has always been a bit tricky. In fact, |
| 33 | * we (and most others) have been getting it wrong in small ways for |
| 34 | * years. Recently this has caused real trouble for the ARM V8 build. |
| 35 | * In this file we attempt to finally get it right for all variations |
| 36 | * of endian-ness and word size and target architectures and |
| 37 | * architectures we might get run on. Phew!. To do this we borrow a |
| 38 | * page from the FreeBSD NFS xdr model (see elf_ehdr and elf_phdr), |
| 39 | * the Plan 9 endianness functions (see xdr.c), and Go interfaces (see |
| 40 | * how we use buffer structs in this file). This ends up being a bit |
| 41 | * wordy at the lowest level, but greatly simplifies the elf parsing |
| 42 | * code and removes a common source of bugs, namely, forgetting to |
| 43 | * flip type endianness when referencing a struct member. |
| 44 | * |
| 45 | * ELF files can have four combinations of data layout: 32/64, and |
| 46 | * big/little endian. Further, to add to the fun, depending on the |
| 47 | * word size, the size of the ELF structs varies. The coreboot SELF |
| 48 | * format is simpler in theory: it's supposed to be always BE, and the |
| 49 | * various struct members allow room for growth: the entry point is |
| 50 | * always 64 bits, for example, so the size of a SELF struct is |
| 51 | * constant, regardless of target architecture word size. Hence, we |
| 52 | * need to do some transformation of the ELF files. |
| 53 | * |
| 54 | * A given architecture, realistically, only supports one of the four |
| 55 | * combinations at a time as the 'native' format. Hence, our code has |
| 56 | * been sprinkled with every variation of [nh]to[hn][sll] over the |
| 57 | * years. We've never quite gotten it all right, however, and a quick |
| 58 | * pass over this code revealed another bug. It's all worked because, |
| 59 | * until now, all the working platforms that had CBFS were 32 LE. Even then, |
| 60 | * however, bugs crept in: we recently realized that we're not |
| 61 | * transforming the entry point to big format when we store into the |
| 62 | * SELF image. |
| 63 | * |
| 64 | * The problem is essentially an XDR operation: |
| 65 | * we have something in a foreign format and need to transform it. |
| 66 | * It's most like XDR because: |
| 67 | * 1) the byte order can be wrong |
| 68 | * 2) the word size can be wrong |
| 69 | * 3) the size of elements in the stream depends on the value |
| 70 | * of other elements in the stream |
| 71 | * it's not like XDR because: |
| 72 | * 1) the byte order can be right |
| 73 | * 2) the word size can be right |
| 74 | * 3) the struct members are all on a natural alignment |
| 75 | * |
| 76 | * Hence, this new approach. To cover word size issues, we *always* |
| 77 | * transform the two structs we care about, the file header and |
| 78 | * program header, into a native struct in the 64 bit format: |
| 79 | * |
| 80 | * [32,little] -> [Elf64_Ehdr, Elf64_Phdr] |
| 81 | * [64,little] -> [Elf64_Ehdr, Elf64_Phdr] |
| 82 | * [32,big] -> [Elf64_Ehdr, Elf64_Phdr] |
| 83 | * [64,big] -> [Elf64_Ehdr, Elf64_Phdr] |
| 84 | * Then we just use those structs, and all the need for inline ntoh* goes away, |
| 85 | * as well as all the chances for error. |
| 86 | * This works because all the SELF structs have fields large enough for |
| 87 | * the largest ELF 64 struct members, and all the Elf64 struct members |
| 88 | * are at least large enough for all ELF 32 struct members. |
| 89 | * We end up with one function to do all our ELF parsing, and two functions |
| 90 | * to transform the headers. For the put case, we also have |
| 91 | * XDR functions, and hopefully we'll never again spend 5 years with the |
| 92 | * wrong endian-ness on an output value :-) |
| 93 | * This should work for all word sizes and endianness we hope to target. |
| 94 | * I *really* don't want to be here for 128 bit addresses. |
| 95 | * |
| 96 | * The parse functions are called with a pointer to an input buffer |
| 97 | * struct. One might ask: are there enough bytes in the input buffer? |
| 98 | * We know there need to be at *least* sizeof(Elf32_Ehdr) + |
| 99 | * sizeof(Elf32_Phdr) bytes. Realistically, there has to be some data |
| 100 | * too. If we start to worry, though we have not in the past, we |
| 101 | * might apply the simple test: the input buffer needs to be at least |
| 102 | * sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) bytes because, even if it's |
| 103 | * ELF 32, there's got to be *some* data! This is not theoretically |
| 104 | * accurate but it is actually good enough in practice. It allows the |
| 105 | * header transformation code to ignore the possibility of underrun. |
| 106 | * |
| 107 | * We also must accomodate different ELF files, and hence formats, |
| 108 | * in the same cbfs invocation. We might load a 64-bit payload |
| 109 | * on a 32-bit machine; we might even have a mixed armv7/armv8 |
| 110 | * SOC or even a system with an x86/ARM! |
| 111 | * |
| 112 | * A possibly problematic (though unlikely to be so) assumption |
| 113 | * is that we expect the BIOS to remain in the lowest 32 bits |
| 114 | * of the physical address space. Since ARMV8 has standardized |
| 115 | * on that, and x86_64 also has, this seems a safe assumption. |
| 116 | * |
| 117 | * To repeat, ELF structs are different sizes because ELF struct |
| 118 | * members are different sizes, depending on values in the ELF file |
| 119 | * header. For this we use the functions defined in xdr.c, which |
| 120 | * consume bytes, convert the endianness, and advance the data pointer |
| 121 | * in the buffer struct. |
| 122 | */ |
| 123 | |
Aaron Durbin | aa8784c | 2014-03-05 12:01:36 -0600 | [diff] [blame] | 124 | |
| 125 | static int iself(const void *input) |
| 126 | { |
| 127 | const Elf32_Ehdr *ehdr = input; |
| 128 | return !memcmp(ehdr->e_ident, ELFMAG, 4); |
| 129 | } |
| 130 | |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 131 | /* Get the ident array, so we can figure out |
| 132 | * endian-ness, word size, and in future other useful |
| 133 | * parameters |
| 134 | */ |
| 135 | static void |
| 136 | elf_eident(struct buffer *input, Elf64_Ehdr *ehdr) |
| 137 | { |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 138 | bgets(input, ehdr->e_ident, sizeof(ehdr->e_ident)); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 139 | } |
| 140 | |
| 141 | |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 142 | static int |
| 143 | check_size(const struct buffer *b, size_t offset, size_t size, const char *desc) |
| 144 | { |
| 145 | if (size == 0) |
| 146 | return 0; |
| 147 | |
| 148 | if (offset >= buffer_size(b) || (offset + size) > buffer_size(b)) { |
| 149 | ERROR("The file is not large enough for the '%s'. " |
Paul Menzel | 470c37c | 2014-03-16 00:15:57 +0100 | [diff] [blame] | 150 | "%zu bytes @ offset %zu, input %zu bytes.\n", |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 151 | desc, size, offset, buffer_size(b)); |
| 152 | return -1; |
| 153 | } |
| 154 | return 0; |
| 155 | } |
| 156 | |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 157 | static void |
| 158 | elf_ehdr(struct buffer *input, Elf64_Ehdr *ehdr, struct xdr *xdr, int bit64) |
| 159 | { |
| 160 | ehdr->e_type = xdr->get16(input); |
| 161 | ehdr->e_machine = xdr->get16(input); |
| 162 | ehdr->e_version = xdr->get32(input); |
| 163 | if (bit64){ |
| 164 | ehdr->e_entry = xdr->get64(input); |
| 165 | ehdr->e_phoff = xdr->get64(input); |
| 166 | ehdr->e_shoff = xdr->get64(input); |
| 167 | } else { |
| 168 | ehdr->e_entry = xdr->get32(input); |
| 169 | ehdr->e_phoff = xdr->get32(input); |
| 170 | ehdr->e_shoff = xdr->get32(input); |
| 171 | } |
| 172 | ehdr->e_flags = xdr->get32(input); |
| 173 | ehdr->e_ehsize = xdr->get16(input); |
| 174 | ehdr->e_phentsize = xdr->get16(input); |
| 175 | ehdr->e_phnum = xdr->get16(input); |
| 176 | ehdr->e_shentsize = xdr->get16(input); |
| 177 | ehdr->e_shnum = xdr->get16(input); |
| 178 | ehdr->e_shstrndx = xdr->get16(input); |
| 179 | } |
| 180 | |
| 181 | static void |
| 182 | elf_phdr(struct buffer *pinput, Elf64_Phdr *phdr, |
| 183 | int entsize, struct xdr *xdr, int bit64) |
| 184 | { |
| 185 | /* |
| 186 | * The entsize need not be sizeof(*phdr). |
| 187 | * Hence, it is easier to keep a copy of the input, |
| 188 | * as the xdr functions may not advance the input |
| 189 | * pointer the full entsize; rather than get tricky |
| 190 | * we just advance it below. |
| 191 | */ |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 192 | struct buffer input; |
| 193 | buffer_clone(&input, pinput); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 194 | if (bit64){ |
| 195 | phdr->p_type = xdr->get32(&input); |
| 196 | phdr->p_flags = xdr->get32(&input); |
| 197 | phdr->p_offset = xdr->get64(&input); |
| 198 | phdr->p_vaddr = xdr->get64(&input); |
| 199 | phdr->p_paddr = xdr->get64(&input); |
| 200 | phdr->p_filesz = xdr->get64(&input); |
| 201 | phdr->p_memsz = xdr->get64(&input); |
| 202 | phdr->p_align = xdr->get64(&input); |
| 203 | } else { |
| 204 | phdr->p_type = xdr->get32(&input); |
| 205 | phdr->p_offset = xdr->get32(&input); |
| 206 | phdr->p_vaddr = xdr->get32(&input); |
| 207 | phdr->p_paddr = xdr->get32(&input); |
| 208 | phdr->p_filesz = xdr->get32(&input); |
| 209 | phdr->p_memsz = xdr->get32(&input); |
| 210 | phdr->p_flags = xdr->get32(&input); |
| 211 | phdr->p_align = xdr->get32(&input); |
| 212 | } |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 213 | buffer_seek(pinput, entsize); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 214 | } |
| 215 | |
| 216 | static void |
| 217 | elf_shdr(struct buffer *pinput, Elf64_Shdr *shdr, |
| 218 | int entsize, struct xdr *xdr, int bit64) |
| 219 | { |
| 220 | /* |
| 221 | * The entsize need not be sizeof(*shdr). |
| 222 | * Hence, it is easier to keep a copy of the input, |
| 223 | * as the xdr functions may not advance the input |
| 224 | * pointer the full entsize; rather than get tricky |
| 225 | * we just advance it below. |
| 226 | */ |
| 227 | struct buffer input = *pinput; |
| 228 | if (bit64){ |
| 229 | shdr->sh_name = xdr->get32(&input); |
| 230 | shdr->sh_type = xdr->get32(&input); |
| 231 | shdr->sh_flags = xdr->get64(&input); |
| 232 | shdr->sh_addr = xdr->get64(&input); |
| 233 | shdr->sh_offset = xdr->get64(&input); |
| 234 | shdr->sh_size= xdr->get64(&input); |
| 235 | shdr->sh_link = xdr->get32(&input); |
| 236 | shdr->sh_info = xdr->get32(&input); |
| 237 | shdr->sh_addralign = xdr->get64(&input); |
| 238 | shdr->sh_entsize = xdr->get64(&input); |
| 239 | } else { |
| 240 | shdr->sh_name = xdr->get32(&input); |
| 241 | shdr->sh_type = xdr->get32(&input); |
| 242 | shdr->sh_flags = xdr->get32(&input); |
| 243 | shdr->sh_addr = xdr->get32(&input); |
| 244 | shdr->sh_offset = xdr->get32(&input); |
| 245 | shdr->sh_size = xdr->get32(&input); |
| 246 | shdr->sh_link = xdr->get32(&input); |
| 247 | shdr->sh_info = xdr->get32(&input); |
| 248 | shdr->sh_addralign = xdr->get32(&input); |
| 249 | shdr->sh_entsize = xdr->get32(&input); |
| 250 | } |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 251 | buffer_seek(pinput, entsize); |
| 252 | } |
| 253 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 254 | static int |
| 255 | phdr_read(const struct buffer *in, struct parsed_elf *pelf, |
| 256 | struct xdr *xdr, int bit64) |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 257 | { |
| 258 | struct buffer b; |
| 259 | Elf64_Phdr *phdr; |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 260 | Elf64_Ehdr *ehdr; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 261 | int i; |
| 262 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 263 | ehdr = &pelf->ehdr; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 264 | /* cons up an input buffer for the headers. |
| 265 | * Note that the program headers can be anywhere, |
| 266 | * per the ELF spec, You'd be surprised how many ELF |
| 267 | * readers miss this little detail. |
| 268 | */ |
| 269 | buffer_splice(&b, in, ehdr->e_phoff, ehdr->e_phentsize * ehdr->e_phnum); |
| 270 | if (check_size(in, ehdr->e_phoff, buffer_size(&b), "program headers")) |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 271 | return -1; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 272 | |
| 273 | /* gather up all the phdrs. |
| 274 | * We do them all at once because there is more |
| 275 | * than one loop over all the phdrs. |
| 276 | */ |
Aaron Durbin | b1b5118 | 2014-03-05 14:54:13 -0600 | [diff] [blame] | 277 | phdr = calloc(ehdr->e_phnum, sizeof(*phdr)); |
Aaron Durbin | a31ff73 | 2014-03-07 15:23:05 -0600 | [diff] [blame] | 278 | for (i = 0; i < ehdr->e_phnum; i++) { |
| 279 | DEBUG("Parsing segment %d\n", i); |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 280 | elf_phdr(&b, &phdr[i], ehdr->e_phentsize, xdr, bit64); |
| 281 | |
Aaron Durbin | a31ff73 | 2014-03-07 15:23:05 -0600 | [diff] [blame] | 282 | /* Ensure the contents are valid within the elf file. */ |
| 283 | if (check_size(in, phdr[i].p_offset, phdr[i].p_filesz, |
Patrick Georgi | a65c21e | 2014-08-09 16:58:00 +0200 | [diff] [blame] | 284 | "segment contents")) { |
| 285 | free(phdr); |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 286 | return -1; |
Patrick Georgi | a65c21e | 2014-08-09 16:58:00 +0200 | [diff] [blame] | 287 | } |
Aaron Durbin | a31ff73 | 2014-03-07 15:23:05 -0600 | [diff] [blame] | 288 | } |
| 289 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 290 | pelf->phdr = phdr; |
| 291 | |
| 292 | return 0; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 293 | } |
| 294 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 295 | static int |
| 296 | shdr_read(const struct buffer *in, struct parsed_elf *pelf, |
| 297 | struct xdr *xdr, int bit64) |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 298 | { |
| 299 | struct buffer b; |
| 300 | Elf64_Shdr *shdr; |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 301 | Elf64_Ehdr *ehdr; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 302 | int i; |
| 303 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 304 | ehdr = &pelf->ehdr; |
| 305 | |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 306 | /* cons up an input buffer for the section headers. |
| 307 | * Note that the section headers can be anywhere, |
| 308 | * per the ELF spec, You'd be surprised how many ELF |
| 309 | * readers miss this little detail. |
| 310 | */ |
| 311 | buffer_splice(&b, in, ehdr->e_shoff, ehdr->e_shentsize * ehdr->e_shnum); |
| 312 | if (check_size(in, ehdr->e_shoff, buffer_size(&b), "section headers")) |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 313 | return -1; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 314 | |
| 315 | /* gather up all the shdrs. */ |
Aaron Durbin | b1b5118 | 2014-03-05 14:54:13 -0600 | [diff] [blame] | 316 | shdr = calloc(ehdr->e_shnum, sizeof(*shdr)); |
Aaron Durbin | a31ff73 | 2014-03-07 15:23:05 -0600 | [diff] [blame] | 317 | for (i = 0; i < ehdr->e_shnum; i++) { |
| 318 | DEBUG("Parsing section %d\n", i); |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 319 | elf_shdr(&b, &shdr[i], ehdr->e_shentsize, xdr, bit64); |
Aaron Durbin | a31ff73 | 2014-03-07 15:23:05 -0600 | [diff] [blame] | 320 | } |
| 321 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 322 | pelf->shdr = shdr; |
| 323 | |
| 324 | return 0; |
| 325 | } |
| 326 | |
Aaron Durbin | ccb5ad8 | 2014-03-05 13:57:30 -0600 | [diff] [blame] | 327 | static int |
| 328 | reloc_read(const struct buffer *in, struct parsed_elf *pelf, |
| 329 | struct xdr *xdr, int bit64) |
| 330 | { |
| 331 | struct buffer b; |
| 332 | Elf64_Word i; |
| 333 | Elf64_Ehdr *ehdr; |
| 334 | |
| 335 | ehdr = &pelf->ehdr; |
| 336 | pelf->relocs = calloc(ehdr->e_shnum, sizeof(Elf64_Rela *)); |
| 337 | |
| 338 | /* Allocate array for each section that contains relocation entries. */ |
| 339 | for (i = 0; i < ehdr->e_shnum; i++) { |
| 340 | Elf64_Shdr *shdr; |
| 341 | Elf64_Rela *rela; |
| 342 | Elf64_Xword j; |
| 343 | Elf64_Xword nrelocs; |
| 344 | int is_rela; |
| 345 | |
| 346 | shdr = &pelf->shdr[i]; |
| 347 | |
| 348 | /* Only process REL and RELA sections. */ |
| 349 | if (shdr->sh_type != SHT_REL && shdr->sh_type != SHT_RELA) |
| 350 | continue; |
| 351 | |
| 352 | DEBUG("Checking relocation section %u\n", i); |
| 353 | |
| 354 | /* Ensure the section that relocations apply is a valid. */ |
| 355 | if (shdr->sh_info >= ehdr->e_shnum || |
| 356 | shdr->sh_info == SHN_UNDEF) { |
| 357 | ERROR("Relocations apply to an invalid section: %u\n", |
| 358 | shdr[i].sh_info); |
| 359 | return -1; |
| 360 | } |
| 361 | |
| 362 | is_rela = shdr->sh_type == SHT_RELA; |
| 363 | |
| 364 | /* Determine the number relocations in this section. */ |
| 365 | nrelocs = shdr->sh_size / shdr->sh_entsize; |
| 366 | |
| 367 | pelf->relocs[i] = calloc(nrelocs, sizeof(Elf64_Rela)); |
| 368 | |
| 369 | buffer_splice(&b, in, shdr->sh_offset, shdr->sh_size); |
| 370 | if (check_size(in, shdr->sh_offset, buffer_size(&b), |
| 371 | "relocation section")) { |
| 372 | ERROR("Relocation section %u failed.\n", i); |
| 373 | return -1; |
| 374 | } |
| 375 | |
| 376 | rela = pelf->relocs[i]; |
| 377 | for (j = 0; j < nrelocs; j++) { |
| 378 | if (bit64) { |
| 379 | rela->r_offset = xdr->get64(&b); |
| 380 | rela->r_info = xdr->get64(&b); |
| 381 | if (is_rela) |
| 382 | rela->r_addend = xdr->get64(&b); |
| 383 | } else { |
| 384 | uint32_t r_info; |
| 385 | |
| 386 | rela->r_offset = xdr->get32(&b); |
| 387 | r_info = xdr->get32(&b); |
| 388 | rela->r_info = ELF64_R_INFO(ELF32_R_SYM(r_info), |
| 389 | ELF32_R_TYPE(r_info)); |
| 390 | if (is_rela) |
| 391 | rela->r_addend = xdr->get32(&b); |
| 392 | } |
| 393 | rela++; |
| 394 | } |
| 395 | } |
| 396 | |
| 397 | return 0; |
| 398 | } |
| 399 | |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 400 | static int strtab_read(const struct buffer *in, struct parsed_elf *pelf) |
| 401 | { |
| 402 | Elf64_Ehdr *ehdr; |
| 403 | Elf64_Word i; |
| 404 | |
| 405 | ehdr = &pelf->ehdr; |
| 406 | |
| 407 | if (ehdr->e_shstrndx >= ehdr->e_shnum) { |
| 408 | ERROR("Section header string table index out of range: %d\n", |
| 409 | ehdr->e_shstrndx); |
| 410 | return -1; |
| 411 | } |
| 412 | |
| 413 | /* For each section of type SHT_STRTAB create a symtab buffer. */ |
| 414 | pelf->strtabs = calloc(ehdr->e_shnum, sizeof(struct buffer *)); |
| 415 | |
| 416 | for (i = 0; i < ehdr->e_shnum; i++) { |
| 417 | struct buffer *b; |
| 418 | Elf64_Shdr *shdr = &pelf->shdr[i]; |
| 419 | |
| 420 | if (shdr->sh_type != SHT_STRTAB) |
| 421 | continue; |
| 422 | |
| 423 | b = calloc(1, sizeof(*b)); |
| 424 | buffer_splice(b, in, shdr->sh_offset, shdr->sh_size); |
| 425 | if (check_size(in, shdr->sh_offset, buffer_size(b), "strtab")) { |
| 426 | ERROR("STRTAB section not within bounds: %d\n", i); |
Patrick Georgi | a65c21e | 2014-08-09 16:58:00 +0200 | [diff] [blame] | 427 | free(b); |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 428 | return -1; |
| 429 | } |
| 430 | pelf->strtabs[i] = b; |
| 431 | } |
| 432 | |
| 433 | return 0; |
| 434 | } |
| 435 | |
Aaron Durbin | c078094 | 2014-03-05 16:41:27 -0600 | [diff] [blame] | 436 | static int |
| 437 | symtab_read(const struct buffer *in, struct parsed_elf *pelf, |
| 438 | struct xdr *xdr, int bit64) |
| 439 | { |
| 440 | Elf64_Ehdr *ehdr; |
| 441 | Elf64_Shdr *shdr; |
| 442 | Elf64_Half i; |
| 443 | Elf64_Xword nsyms; |
| 444 | Elf64_Sym *sym; |
| 445 | struct buffer b; |
| 446 | |
| 447 | ehdr = &pelf->ehdr; |
| 448 | |
| 449 | shdr = NULL; |
| 450 | for (i = 0; i < ehdr->e_shnum; i++) { |
| 451 | if (pelf->shdr[i].sh_type != SHT_SYMTAB) |
| 452 | continue; |
| 453 | |
| 454 | if (shdr != NULL) { |
| 455 | ERROR("Multiple symbol sections found. %u and %u\n", |
| 456 | (unsigned int)(shdr - pelf->shdr), i); |
| 457 | return -1; |
| 458 | } |
| 459 | |
| 460 | shdr = &pelf->shdr[i]; |
| 461 | } |
| 462 | |
| 463 | if (shdr == NULL) { |
| 464 | ERROR("No symbol table found.\n"); |
| 465 | return -1; |
| 466 | } |
| 467 | |
| 468 | buffer_splice(&b, in, shdr->sh_offset, shdr->sh_size); |
| 469 | if (check_size(in, shdr->sh_offset, buffer_size(&b), "symtab")) |
| 470 | return -1; |
| 471 | |
| 472 | nsyms = shdr->sh_size / shdr->sh_entsize; |
| 473 | |
| 474 | pelf->syms = calloc(nsyms, sizeof(Elf64_Sym)); |
| 475 | |
| 476 | for (i = 0; i < nsyms; i++) { |
| 477 | sym = &pelf->syms[i]; |
| 478 | |
| 479 | if (bit64) { |
| 480 | sym->st_name = xdr->get32(&b); |
| 481 | sym->st_info = xdr->get8(&b); |
| 482 | sym->st_other = xdr->get8(&b); |
| 483 | sym->st_shndx = xdr->get16(&b); |
| 484 | sym->st_value = xdr->get64(&b); |
| 485 | sym->st_size = xdr->get64(&b); |
| 486 | } else { |
| 487 | sym->st_name = xdr->get32(&b); |
| 488 | sym->st_value = xdr->get32(&b); |
| 489 | sym->st_size = xdr->get32(&b); |
| 490 | sym->st_info = xdr->get8(&b); |
| 491 | sym->st_other = xdr->get8(&b); |
| 492 | sym->st_shndx = xdr->get16(&b); |
| 493 | } |
| 494 | } |
| 495 | |
| 496 | return 0; |
| 497 | } |
| 498 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 499 | int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags) |
| 500 | { |
| 501 | struct xdr *xdr = &xdr_le; |
| 502 | int bit64 = 0; |
| 503 | struct buffer input; |
| 504 | Elf64_Ehdr *ehdr; |
| 505 | |
| 506 | /* Zero out the parsed elf structure. */ |
| 507 | memset(pelf, 0, sizeof(*pelf)); |
| 508 | |
| 509 | if (!iself(buffer_get(pinput))) { |
| 510 | ERROR("The stage file is not in ELF format!\n"); |
| 511 | return -1; |
| 512 | } |
| 513 | |
| 514 | buffer_clone(&input, pinput); |
| 515 | ehdr = &pelf->ehdr; |
| 516 | elf_eident(&input, ehdr); |
| 517 | bit64 = ehdr->e_ident[EI_CLASS] == ELFCLASS64; |
| 518 | /* Assume LE unless we are sure otherwise. |
| 519 | * We're not going to take on the task of |
| 520 | * fully validating the ELF file. That way |
| 521 | * lies madness. |
| 522 | */ |
| 523 | if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) |
| 524 | xdr = &xdr_be; |
| 525 | |
| 526 | elf_ehdr(&input, ehdr, xdr, bit64); |
| 527 | |
Aaron Durbin | ccb5ad8 | 2014-03-05 13:57:30 -0600 | [diff] [blame] | 528 | /* Relocation processing requires section header parsing. */ |
| 529 | if (flags & ELF_PARSE_RELOC) |
| 530 | flags |= ELF_PARSE_SHDR; |
| 531 | |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 532 | /* String table processing requires section header parsing. */ |
| 533 | if (flags & ELF_PARSE_STRTAB) |
| 534 | flags |= ELF_PARSE_SHDR; |
| 535 | |
Aaron Durbin | c078094 | 2014-03-05 16:41:27 -0600 | [diff] [blame] | 536 | /* Symbole table processing requires section header parsing. */ |
| 537 | if (flags & ELF_PARSE_SYMTAB) |
| 538 | flags |= ELF_PARSE_SHDR; |
| 539 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 540 | if ((flags & ELF_PARSE_PHDR) && phdr_read(pinput, pelf, xdr, bit64)) |
| 541 | goto fail; |
| 542 | |
| 543 | if ((flags & ELF_PARSE_SHDR) && shdr_read(pinput, pelf, xdr, bit64)) |
| 544 | goto fail; |
| 545 | |
Aaron Durbin | ccb5ad8 | 2014-03-05 13:57:30 -0600 | [diff] [blame] | 546 | if ((flags & ELF_PARSE_RELOC) && reloc_read(pinput, pelf, xdr, bit64)) |
| 547 | goto fail; |
| 548 | |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 549 | if ((flags & ELF_PARSE_STRTAB) && strtab_read(pinput, pelf)) |
| 550 | goto fail; |
| 551 | |
Aaron Durbin | c078094 | 2014-03-05 16:41:27 -0600 | [diff] [blame] | 552 | if ((flags & ELF_PARSE_SYMTAB) && symtab_read(pinput, pelf, xdr, bit64)) |
| 553 | goto fail; |
| 554 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 555 | return 0; |
| 556 | |
| 557 | fail: |
| 558 | parsed_elf_destroy(pelf); |
| 559 | return -1; |
| 560 | } |
| 561 | |
| 562 | void parsed_elf_destroy(struct parsed_elf *pelf) |
| 563 | { |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 564 | Elf64_Half i; |
| 565 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 566 | free(pelf->phdr); |
| 567 | free(pelf->shdr); |
Aaron Durbin | ccb5ad8 | 2014-03-05 13:57:30 -0600 | [diff] [blame] | 568 | if (pelf->relocs != NULL) { |
Aaron Durbin | ccb5ad8 | 2014-03-05 13:57:30 -0600 | [diff] [blame] | 569 | for (i = 0; i < pelf->ehdr.e_shnum; i++) |
| 570 | free(pelf->relocs[i]); |
| 571 | } |
| 572 | free(pelf->relocs); |
Aaron Durbin | c3e6e14 | 2014-03-05 14:33:42 -0600 | [diff] [blame] | 573 | |
| 574 | if (pelf->strtabs != NULL) { |
| 575 | for (i = 0; i < pelf->ehdr.e_shnum; i++) |
| 576 | free(pelf->strtabs[i]); |
| 577 | } |
| 578 | free(pelf->strtabs); |
Aaron Durbin | c078094 | 2014-03-05 16:41:27 -0600 | [diff] [blame] | 579 | free(pelf->syms); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 580 | } |
| 581 | |
| 582 | /* Get the headers from the buffer. |
| 583 | * Return -1 in the event of an error. |
| 584 | * The section headers are optional; if NULL |
| 585 | * is passed in for pshdr they won't be parsed. |
| 586 | * We don't (yet) make payload parsing optional |
| 587 | * because we've never seen a use case. |
| 588 | */ |
| 589 | int |
| 590 | elf_headers(const struct buffer *pinput, |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 591 | Elf64_Ehdr *ehdr, |
| 592 | Elf64_Phdr **pphdr, |
| 593 | Elf64_Shdr **pshdr) |
| 594 | { |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 595 | struct parsed_elf pelf; |
| 596 | int flags; |
Aaron Durbin | a983cea | 2014-03-04 22:08:05 -0600 | [diff] [blame] | 597 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 598 | flags = ELF_PARSE_PHDR; |
| 599 | |
| 600 | if (pshdr != NULL) |
| 601 | flags |= ELF_PARSE_SHDR; |
| 602 | |
| 603 | if (parse_elf(pinput, &pelf, flags)) |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 604 | return -1; |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 605 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 606 | /* Copy out the parsed elf header. */ |
| 607 | memcpy(ehdr, &pelf.ehdr, sizeof(*ehdr)); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 608 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 609 | *pphdr = calloc(ehdr->e_phnum, sizeof(Elf64_Phdr)); |
| 610 | memcpy(*pphdr, pelf.phdr, ehdr->e_phnum * sizeof(Elf64_Phdr)); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 611 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 612 | if (pshdr != NULL) { |
| 613 | *pshdr = calloc(ehdr->e_shnum, sizeof(Elf64_Shdr)); |
| 614 | memcpy(*pshdr, pelf.shdr, ehdr->e_shnum * sizeof(Elf64_Shdr)); |
| 615 | } |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 616 | |
Aaron Durbin | d0f6165 | 2014-03-05 13:09:55 -0600 | [diff] [blame] | 617 | parsed_elf_destroy(&pelf); |
Ronald G. Minnich | a8a133d | 2013-12-30 13:16:18 -0800 | [diff] [blame] | 618 | |
| 619 | return 0; |
| 620 | } |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 621 | |
| 622 | /* ELF Writing Support |
| 623 | * |
| 624 | * The ELF file is written according to the following layout: |
| 625 | * +------------------+ |
| 626 | * | ELF Header | |
| 627 | * +------------------+ |
| 628 | * | Section Headers | |
| 629 | * +------------------+ |
| 630 | * | Program Headers | |
| 631 | * +------------------+ |
| 632 | * | String table | |
| 633 | * +------------------+ <- 4KiB Aligned |
| 634 | * | Code/Data | |
| 635 | * +------------------+ |
| 636 | */ |
| 637 | |
Aaron Durbin | 4f930c9 | 2015-10-27 16:21:55 -0500 | [diff] [blame] | 638 | void elf_init_eheader(Elf64_Ehdr *ehdr, int machine, int nbits, int endian) |
| 639 | { |
| 640 | memset(ehdr, 0, sizeof(*ehdr)); |
| 641 | ehdr->e_ident[EI_MAG0] = ELFMAG0; |
| 642 | ehdr->e_ident[EI_MAG1] = ELFMAG1; |
| 643 | ehdr->e_ident[EI_MAG2] = ELFMAG2; |
| 644 | ehdr->e_ident[EI_MAG3] = ELFMAG3; |
| 645 | ehdr->e_ident[EI_CLASS] = nbits; |
| 646 | ehdr->e_ident[EI_DATA] = endian; |
| 647 | ehdr->e_ident[EI_VERSION] = EV_CURRENT; |
| 648 | ehdr->e_type = ET_EXEC; |
| 649 | ehdr->e_machine = machine; |
| 650 | ehdr->e_version = EV_CURRENT; |
| 651 | if (nbits == ELFCLASS64) { |
| 652 | ehdr->e_ehsize = sizeof(Elf64_Ehdr); |
| 653 | ehdr->e_phentsize = sizeof(Elf64_Phdr); |
| 654 | ehdr->e_shentsize = sizeof(Elf64_Shdr); |
| 655 | } else { |
| 656 | ehdr->e_ehsize = sizeof(Elf32_Ehdr); |
| 657 | ehdr->e_phentsize = sizeof(Elf32_Phdr); |
| 658 | ehdr->e_shentsize = sizeof(Elf32_Shdr); |
| 659 | } |
| 660 | } |
| 661 | |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 662 | /* Arbitray maximum number of sections. */ |
| 663 | #define MAX_SECTIONS 16 |
| 664 | struct elf_writer_section { |
| 665 | Elf64_Shdr shdr; |
| 666 | struct buffer content; |
| 667 | const char *name; |
| 668 | }; |
| 669 | |
| 670 | struct elf_writer |
| 671 | { |
| 672 | Elf64_Ehdr ehdr; |
| 673 | struct xdr *xdr; |
| 674 | size_t num_secs; |
| 675 | struct elf_writer_section sections[MAX_SECTIONS]; |
| 676 | Elf64_Phdr *phdrs; |
| 677 | struct elf_writer_section *shstrtab; |
| 678 | int bit64; |
| 679 | }; |
| 680 | |
| 681 | struct elf_writer *elf_writer_init(const Elf64_Ehdr *ehdr) |
| 682 | { |
| 683 | struct elf_writer *ew; |
| 684 | Elf64_Shdr shdr; |
| 685 | struct buffer empty_buffer; |
| 686 | |
| 687 | if (!iself(ehdr)) |
| 688 | return NULL; |
| 689 | |
| 690 | ew = calloc(1, sizeof(*ew)); |
| 691 | |
| 692 | memcpy(&ew->ehdr, ehdr, sizeof(ew->ehdr)); |
| 693 | |
| 694 | ew->bit64 = ew->ehdr.e_ident[EI_CLASS] == ELFCLASS64; |
| 695 | |
| 696 | /* Set the endinan ops. */ |
| 697 | if (ew->ehdr.e_ident[EI_DATA] == ELFDATA2MSB) |
| 698 | ew->xdr = &xdr_be; |
| 699 | else |
| 700 | ew->xdr = &xdr_le; |
| 701 | |
| 702 | /* Reset count and offsets */ |
| 703 | ew->ehdr.e_phoff = 0; |
| 704 | ew->ehdr.e_shoff = 0; |
| 705 | ew->ehdr.e_shnum = 0; |
| 706 | ew->ehdr.e_phnum = 0; |
| 707 | |
| 708 | memset(&empty_buffer, 0, sizeof(empty_buffer)); |
| 709 | memset(&shdr, 0, sizeof(shdr)); |
| 710 | |
| 711 | /* Add SHT_NULL section header. */ |
| 712 | shdr.sh_type = SHT_NULL; |
| 713 | elf_writer_add_section(ew, &shdr, &empty_buffer, NULL); |
| 714 | |
| 715 | /* Add section header string table and maintain reference to it. */ |
| 716 | shdr.sh_type = SHT_STRTAB; |
| 717 | elf_writer_add_section(ew, &shdr, &empty_buffer, ".shstrtab"); |
| 718 | ew->ehdr.e_shstrndx = ew->num_secs - 1; |
| 719 | ew->shstrtab = &ew->sections[ew->ehdr.e_shstrndx]; |
| 720 | |
| 721 | return ew; |
| 722 | } |
| 723 | |
| 724 | /* |
| 725 | * Clean up any internal state represented by ew. Aftewards the elf_writer |
| 726 | * is invalid. |
| 727 | */ |
| 728 | void elf_writer_destroy(struct elf_writer *ew) |
| 729 | { |
| 730 | if (ew->phdrs != NULL) |
| 731 | free(ew->phdrs); |
| 732 | free(ew); |
| 733 | } |
| 734 | |
| 735 | /* |
| 736 | * Add a section to the ELF file. Section type, flags, and memsize are |
| 737 | * maintained from the passed in Elf64_Shdr. The buffer represents the |
| 738 | * content of the section while the name is the name of section itself. |
| 739 | * Returns < 0 on error, 0 on success. |
| 740 | */ |
| 741 | int elf_writer_add_section(struct elf_writer *ew, const Elf64_Shdr *shdr, |
| 742 | struct buffer *contents, const char *name) |
| 743 | { |
| 744 | struct elf_writer_section *newsh; |
| 745 | |
| 746 | if (ew->num_secs == MAX_SECTIONS) |
| 747 | return -1; |
| 748 | |
| 749 | newsh = &ew->sections[ew->num_secs]; |
| 750 | ew->num_secs++; |
| 751 | |
| 752 | memcpy(&newsh->shdr, shdr, sizeof(newsh->shdr)); |
| 753 | newsh->shdr.sh_offset = 0; |
| 754 | |
| 755 | newsh->name = name; |
| 756 | if (contents != NULL) |
| 757 | buffer_clone(&newsh->content, contents); |
| 758 | |
| 759 | return 0; |
| 760 | } |
| 761 | |
| 762 | static void ehdr_write(struct elf_writer *ew, struct buffer *m) |
| 763 | { |
| 764 | int i; |
| 765 | |
| 766 | for (i = 0; i < EI_NIDENT; i++) |
| 767 | ew->xdr->put8(m, ew->ehdr.e_ident[i]); |
| 768 | ew->xdr->put16(m, ew->ehdr.e_type); |
| 769 | ew->xdr->put16(m, ew->ehdr.e_machine); |
| 770 | ew->xdr->put32(m, ew->ehdr.e_version); |
| 771 | if (ew->bit64) { |
| 772 | ew->xdr->put64(m, ew->ehdr.e_entry); |
| 773 | ew->xdr->put64(m, ew->ehdr.e_phoff); |
| 774 | ew->xdr->put64(m, ew->ehdr.e_shoff); |
| 775 | } else { |
| 776 | ew->xdr->put32(m, ew->ehdr.e_entry); |
| 777 | ew->xdr->put32(m, ew->ehdr.e_phoff); |
| 778 | ew->xdr->put32(m, ew->ehdr.e_shoff); |
| 779 | } |
| 780 | ew->xdr->put32(m, ew->ehdr.e_flags); |
| 781 | ew->xdr->put16(m, ew->ehdr.e_ehsize); |
| 782 | ew->xdr->put16(m, ew->ehdr.e_phentsize); |
| 783 | ew->xdr->put16(m, ew->ehdr.e_phnum); |
| 784 | ew->xdr->put16(m, ew->ehdr.e_shentsize); |
| 785 | ew->xdr->put16(m, ew->ehdr.e_shnum); |
| 786 | ew->xdr->put16(m, ew->ehdr.e_shstrndx); |
| 787 | } |
| 788 | |
| 789 | static void shdr_write(struct elf_writer *ew, size_t n, struct buffer *m) |
| 790 | { |
| 791 | struct xdr *xdr = ew->xdr; |
| 792 | int bit64 = ew->bit64; |
| 793 | struct elf_writer_section *sec = &ew->sections[n]; |
| 794 | Elf64_Shdr *shdr = &sec->shdr; |
| 795 | |
| 796 | xdr->put32(m, shdr->sh_name); |
| 797 | xdr->put32(m, shdr->sh_type); |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 798 | if (bit64) { |
Aaron Durbin | bc349b8 | 2014-08-22 14:05:00 -0500 | [diff] [blame] | 799 | xdr->put64(m, shdr->sh_flags); |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 800 | xdr->put64(m, shdr->sh_addr); |
| 801 | xdr->put64(m, shdr->sh_offset); |
| 802 | xdr->put64(m, shdr->sh_size); |
| 803 | xdr->put32(m, shdr->sh_link); |
| 804 | xdr->put32(m, shdr->sh_info); |
| 805 | xdr->put64(m, shdr->sh_addralign); |
| 806 | xdr->put64(m, shdr->sh_entsize); |
| 807 | } else { |
Aaron Durbin | bc349b8 | 2014-08-22 14:05:00 -0500 | [diff] [blame] | 808 | xdr->put32(m, shdr->sh_flags); |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 809 | xdr->put32(m, shdr->sh_addr); |
| 810 | xdr->put32(m, shdr->sh_offset); |
| 811 | xdr->put32(m, shdr->sh_size); |
| 812 | xdr->put32(m, shdr->sh_link); |
| 813 | xdr->put32(m, shdr->sh_info); |
| 814 | xdr->put32(m, shdr->sh_addralign); |
| 815 | xdr->put32(m, shdr->sh_entsize); |
| 816 | } |
| 817 | } |
| 818 | |
| 819 | static void |
| 820 | phdr_write(struct elf_writer *ew, struct buffer *m, Elf64_Phdr *phdr) |
| 821 | { |
| 822 | if (ew->bit64) { |
| 823 | ew->xdr->put32(m, phdr->p_type); |
| 824 | ew->xdr->put32(m, phdr->p_flags); |
| 825 | ew->xdr->put64(m, phdr->p_offset); |
| 826 | ew->xdr->put64(m, phdr->p_vaddr); |
| 827 | ew->xdr->put64(m, phdr->p_paddr); |
| 828 | ew->xdr->put64(m, phdr->p_filesz); |
| 829 | ew->xdr->put64(m, phdr->p_memsz); |
| 830 | ew->xdr->put64(m, phdr->p_align); |
| 831 | } else { |
| 832 | ew->xdr->put32(m, phdr->p_type); |
| 833 | ew->xdr->put32(m, phdr->p_offset); |
| 834 | ew->xdr->put32(m, phdr->p_vaddr); |
| 835 | ew->xdr->put32(m, phdr->p_paddr); |
| 836 | ew->xdr->put32(m, phdr->p_filesz); |
| 837 | ew->xdr->put32(m, phdr->p_memsz); |
| 838 | ew->xdr->put32(m, phdr->p_flags); |
| 839 | ew->xdr->put32(m, phdr->p_align); |
| 840 | } |
| 841 | |
| 842 | } |
| 843 | |
Aaron Durbin | 8e982ea | 2015-10-28 10:09:07 -0500 | [diff] [blame^] | 844 | static int section_consecutive(struct elf_writer *ew, Elf64_Half secidx) |
| 845 | { |
| 846 | Elf64_Half i; |
| 847 | struct elf_writer_section *prev_alloc = NULL; |
| 848 | |
| 849 | if (secidx == 0) |
| 850 | return 0; |
| 851 | |
| 852 | for (i = 0; i < secidx; i++) { |
| 853 | if (ew->sections[i].shdr.sh_flags & SHF_ALLOC) |
| 854 | prev_alloc = &ew->sections[i]; |
| 855 | } |
| 856 | |
| 857 | if (prev_alloc == NULL) |
| 858 | return 0; |
| 859 | |
| 860 | if (prev_alloc->shdr.sh_addr + prev_alloc->shdr.sh_size == |
| 861 | ew->sections[secidx].shdr.sh_addr) |
| 862 | return 1; |
| 863 | |
| 864 | return 0; |
| 865 | } |
| 866 | |
| 867 | static void write_phdrs(struct elf_writer *ew, struct buffer *phdrs) |
| 868 | { |
| 869 | Elf64_Half i; |
| 870 | Elf64_Phdr phdr; |
| 871 | size_t num_written = 0; |
| 872 | |
| 873 | for (i = 0; i < ew->num_secs; i++) { |
| 874 | struct elf_writer_section *sec = &ew->sections[i]; |
| 875 | |
| 876 | if (!(sec->shdr.sh_flags & SHF_ALLOC)) |
| 877 | continue; |
| 878 | |
| 879 | if (!section_consecutive(ew, i)) { |
| 880 | /* Write out previously set phdr. */ |
| 881 | if (num_written != 0) { |
| 882 | phdr_write(ew, phdrs, &phdr); |
| 883 | num_written++; |
| 884 | } |
| 885 | phdr.p_type = PT_LOAD; |
| 886 | phdr.p_offset = sec->shdr.sh_offset; |
| 887 | phdr.p_vaddr = sec->shdr.sh_addr; |
| 888 | phdr.p_paddr = sec->shdr.sh_addr; |
| 889 | phdr.p_filesz = buffer_size(&sec->content); |
| 890 | phdr.p_memsz = sec->shdr.sh_size; |
| 891 | phdr.p_flags = 0; |
| 892 | if (sec->shdr.sh_flags & SHF_EXECINSTR) |
| 893 | phdr.p_flags |= PF_X | PF_R; |
| 894 | if (sec->shdr.sh_flags & SHF_WRITE) |
| 895 | phdr.p_flags |= PF_W; |
| 896 | phdr.p_align = sec->shdr.sh_addralign; |
| 897 | } else { |
| 898 | /* Accumulate file size and memsize. The assumption |
| 899 | * is that each section is either NOBITS or full |
| 900 | * (sh_size == file size). This is standard in that |
| 901 | * an ELF section doesn't have a file size component. */ |
| 902 | if (sec->shdr.sh_flags & SHF_EXECINSTR) |
| 903 | phdr.p_flags |= PF_X | PF_R; |
| 904 | if (sec->shdr.sh_flags & SHF_WRITE) |
| 905 | phdr.p_flags |= PF_W; |
| 906 | phdr.p_filesz += buffer_size(&sec->content); |
| 907 | phdr.p_memsz += sec->shdr.sh_size; |
| 908 | } |
| 909 | } |
| 910 | |
| 911 | /* Write out the last phdr. */ |
| 912 | if (num_written != ew->ehdr.e_phnum) |
| 913 | phdr_write(ew, phdrs, &phdr); |
| 914 | } |
| 915 | |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 916 | /* |
| 917 | * Serialize the ELF file to the output buffer. Return < 0 on error, |
| 918 | * 0 on success. |
| 919 | */ |
| 920 | int elf_writer_serialize(struct elf_writer *ew, struct buffer *out) |
| 921 | { |
| 922 | Elf64_Half i; |
| 923 | Elf64_Xword metadata_size; |
| 924 | Elf64_Xword program_size; |
| 925 | Elf64_Off shstroffset; |
| 926 | size_t shstrlen; |
| 927 | struct buffer metadata; |
| 928 | struct buffer phdrs; |
| 929 | struct buffer data; |
| 930 | struct buffer *strtab; |
| 931 | |
| 932 | INFO("Writing %zu sections.\n", ew->num_secs); |
| 933 | |
| 934 | /* Determine size of sections to be written. */ |
| 935 | program_size = 0; |
| 936 | /* Start with 1 byte for first byte of section header string table. */ |
| 937 | shstrlen = 1; |
| 938 | for (i = 0; i < ew->num_secs; i++) { |
| 939 | struct elf_writer_section *sec = &ew->sections[i]; |
| 940 | |
Aaron Durbin | 8e982ea | 2015-10-28 10:09:07 -0500 | [diff] [blame^] | 941 | if (sec->shdr.sh_flags & SHF_ALLOC) { |
| 942 | if (!section_consecutive(ew, i)) |
| 943 | ew->ehdr.e_phnum++; |
| 944 | } |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 945 | |
| 946 | program_size += buffer_size(&sec->content); |
| 947 | |
| 948 | /* Keep track of the length sections' names. */ |
| 949 | if (sec->name != NULL) { |
| 950 | sec->shdr.sh_name = shstrlen; |
| 951 | shstrlen += strlen(sec->name) + 1; |
| 952 | } |
| 953 | } |
| 954 | ew->ehdr.e_shnum = ew->num_secs; |
| 955 | metadata_size = 0; |
| 956 | metadata_size += ew->ehdr.e_ehsize; |
| 957 | metadata_size += ew->ehdr.e_shnum * ew->ehdr.e_shentsize; |
| 958 | metadata_size += ew->ehdr.e_phnum * ew->ehdr.e_phentsize; |
| 959 | shstroffset = metadata_size; |
| 960 | /* Align up section header string size and metadata size to 4KiB */ |
| 961 | metadata_size = ALIGN(metadata_size + shstrlen, 4096); |
| 962 | |
| 963 | if (buffer_create(out, metadata_size + program_size, "elfout")) { |
| 964 | ERROR("Could not create output buffer for ELF.\n"); |
| 965 | return -1; |
| 966 | } |
| 967 | |
| 968 | INFO("Created %zu output buffer for ELF file.\n", buffer_size(out)); |
| 969 | |
| 970 | /* |
| 971 | * Write out ELF header. Section headers come right after ELF header |
| 972 | * followed by the program headers. Buffers need to be created first |
| 973 | * to do the writing. |
| 974 | */ |
| 975 | ew->ehdr.e_shoff = ew->ehdr.e_ehsize; |
| 976 | ew->ehdr.e_phoff = ew->ehdr.e_shoff + |
| 977 | ew->ehdr.e_shnum * ew->ehdr.e_shentsize; |
| 978 | |
| 979 | buffer_splice(&metadata, out, 0, metadata_size); |
| 980 | buffer_splice(&phdrs, out, ew->ehdr.e_phoff, |
| 981 | ew->ehdr.e_phnum * ew->ehdr.e_phentsize); |
| 982 | buffer_splice(&data, out, metadata_size, program_size); |
| 983 | /* Set up the section header string table contents. */ |
| 984 | strtab = &ew->shstrtab->content; |
| 985 | buffer_splice(strtab, out, shstroffset, shstrlen); |
| 986 | ew->shstrtab->shdr.sh_size = shstrlen; |
| 987 | |
| 988 | /* Reset current locations. */ |
| 989 | buffer_set_size(&metadata, 0); |
| 990 | buffer_set_size(&data, 0); |
| 991 | buffer_set_size(&phdrs, 0); |
| 992 | buffer_set_size(strtab, 0); |
| 993 | |
| 994 | /* ELF Header */ |
| 995 | ehdr_write(ew, &metadata); |
| 996 | |
| 997 | /* Write out section headers, section strings, section content, and |
| 998 | * program headers. */ |
| 999 | ew->xdr->put8(strtab, 0); |
| 1000 | for (i = 0; i < ew->num_secs; i++) { |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 1001 | struct elf_writer_section *sec = &ew->sections[i]; |
| 1002 | |
| 1003 | /* Update section offsets. Be sure to not update SHT_NULL. */ |
| 1004 | if (sec == ew->shstrtab) |
| 1005 | sec->shdr.sh_offset = shstroffset; |
| 1006 | else if (i != 0) |
| 1007 | sec->shdr.sh_offset = buffer_size(&data) + |
| 1008 | metadata_size; |
| 1009 | shdr_write(ew, i, &metadata); |
| 1010 | |
| 1011 | /* Add section name to string table. */ |
| 1012 | if (sec->name != NULL) |
| 1013 | bputs(strtab, sec->name, strlen(sec->name) + 1); |
| 1014 | |
| 1015 | if (!(sec->shdr.sh_flags & SHF_ALLOC)) |
| 1016 | continue; |
| 1017 | |
| 1018 | bputs(&data, buffer_get(&sec->content), |
| 1019 | buffer_size(&sec->content)); |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 1020 | } |
| 1021 | |
Aaron Durbin | 8e982ea | 2015-10-28 10:09:07 -0500 | [diff] [blame^] | 1022 | write_phdrs(ew, &phdrs); |
| 1023 | |
Aaron Durbin | 36be813 | 2014-03-11 11:48:56 -0500 | [diff] [blame] | 1024 | return 0; |
| 1025 | } |