2013-12-30 22:16:18 +01:00
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/*
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* elf header parsing.
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*
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* Copyright (C) 2013 Google, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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2014-03-05 19:12:09 +01:00
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#include "elfparsing.h"
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2013-12-30 22:16:18 +01:00
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#include "common.h"
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#include "cbfs.h"
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/*
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* Short form: this is complicated, but we've tried making it simple
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* and we keep hitting problems with our ELF parsing.
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*
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* The ELF parsing situation has always been a bit tricky. In fact,
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* we (and most others) have been getting it wrong in small ways for
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* years. Recently this has caused real trouble for the ARM V8 build.
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* In this file we attempt to finally get it right for all variations
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* of endian-ness and word size and target architectures and
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* architectures we might get run on. Phew!. To do this we borrow a
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* page from the FreeBSD NFS xdr model (see elf_ehdr and elf_phdr),
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* the Plan 9 endianness functions (see xdr.c), and Go interfaces (see
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* how we use buffer structs in this file). This ends up being a bit
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* wordy at the lowest level, but greatly simplifies the elf parsing
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* code and removes a common source of bugs, namely, forgetting to
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* flip type endianness when referencing a struct member.
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*
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* ELF files can have four combinations of data layout: 32/64, and
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* big/little endian. Further, to add to the fun, depending on the
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* word size, the size of the ELF structs varies. The coreboot SELF
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* format is simpler in theory: it's supposed to be always BE, and the
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* various struct members allow room for growth: the entry point is
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* always 64 bits, for example, so the size of a SELF struct is
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* constant, regardless of target architecture word size. Hence, we
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* need to do some transformation of the ELF files.
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*
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* A given architecture, realistically, only supports one of the four
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* combinations at a time as the 'native' format. Hence, our code has
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* been sprinkled with every variation of [nh]to[hn][sll] over the
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* years. We've never quite gotten it all right, however, and a quick
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* pass over this code revealed another bug. It's all worked because,
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* until now, all the working platforms that had CBFS were 32 LE. Even then,
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* however, bugs crept in: we recently realized that we're not
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* transforming the entry point to big format when we store into the
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* SELF image.
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*
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* The problem is essentially an XDR operation:
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* we have something in a foreign format and need to transform it.
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* It's most like XDR because:
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* 1) the byte order can be wrong
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* 2) the word size can be wrong
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* 3) the size of elements in the stream depends on the value
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* of other elements in the stream
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* it's not like XDR because:
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* 1) the byte order can be right
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* 2) the word size can be right
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* 3) the struct members are all on a natural alignment
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*
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* Hence, this new approach. To cover word size issues, we *always*
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* transform the two structs we care about, the file header and
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* program header, into a native struct in the 64 bit format:
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*
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* [32,little] -> [Elf64_Ehdr, Elf64_Phdr]
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* [64,little] -> [Elf64_Ehdr, Elf64_Phdr]
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* [32,big] -> [Elf64_Ehdr, Elf64_Phdr]
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* [64,big] -> [Elf64_Ehdr, Elf64_Phdr]
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* Then we just use those structs, and all the need for inline ntoh* goes away,
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* as well as all the chances for error.
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* This works because all the SELF structs have fields large enough for
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* the largest ELF 64 struct members, and all the Elf64 struct members
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* are at least large enough for all ELF 32 struct members.
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* We end up with one function to do all our ELF parsing, and two functions
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* to transform the headers. For the put case, we also have
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* XDR functions, and hopefully we'll never again spend 5 years with the
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* wrong endian-ness on an output value :-)
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* This should work for all word sizes and endianness we hope to target.
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* I *really* don't want to be here for 128 bit addresses.
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*
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* The parse functions are called with a pointer to an input buffer
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* struct. One might ask: are there enough bytes in the input buffer?
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* We know there need to be at *least* sizeof(Elf32_Ehdr) +
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* sizeof(Elf32_Phdr) bytes. Realistically, there has to be some data
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* too. If we start to worry, though we have not in the past, we
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* might apply the simple test: the input buffer needs to be at least
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* sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) bytes because, even if it's
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* ELF 32, there's got to be *some* data! This is not theoretically
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* accurate but it is actually good enough in practice. It allows the
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* header transformation code to ignore the possibility of underrun.
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*
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* We also must accomodate different ELF files, and hence formats,
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* in the same cbfs invocation. We might load a 64-bit payload
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* on a 32-bit machine; we might even have a mixed armv7/armv8
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* SOC or even a system with an x86/ARM!
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*
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* A possibly problematic (though unlikely to be so) assumption
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* is that we expect the BIOS to remain in the lowest 32 bits
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* of the physical address space. Since ARMV8 has standardized
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* on that, and x86_64 also has, this seems a safe assumption.
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*
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* To repeat, ELF structs are different sizes because ELF struct
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* members are different sizes, depending on values in the ELF file
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* header. For this we use the functions defined in xdr.c, which
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* consume bytes, convert the endianness, and advance the data pointer
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* in the buffer struct.
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*/
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2014-03-05 19:01:36 +01:00
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static int iself(const void *input)
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{
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const Elf32_Ehdr *ehdr = input;
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return !memcmp(ehdr->e_ident, ELFMAG, 4);
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}
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2013-12-30 22:16:18 +01:00
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/* Get the ident array, so we can figure out
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* endian-ness, word size, and in future other useful
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* parameters
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*/
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static void
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elf_eident(struct buffer *input, Elf64_Ehdr *ehdr)
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{
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2014-03-05 05:08:05 +01:00
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bgets(input, ehdr->e_ident, sizeof(ehdr->e_ident));
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2013-12-30 22:16:18 +01:00
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}
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2014-03-05 05:08:05 +01:00
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static int
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check_size(const struct buffer *b, size_t offset, size_t size, const char *desc)
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{
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if (size == 0)
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return 0;
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if (offset >= buffer_size(b) || (offset + size) > buffer_size(b)) {
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ERROR("The file is not large enough for the '%s'. "
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2014-03-16 00:15:57 +01:00
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"%zu bytes @ offset %zu, input %zu bytes.\n",
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2014-03-05 05:08:05 +01:00
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desc, size, offset, buffer_size(b));
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return -1;
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}
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return 0;
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}
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2013-12-30 22:16:18 +01:00
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static void
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elf_ehdr(struct buffer *input, Elf64_Ehdr *ehdr, struct xdr *xdr, int bit64)
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{
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ehdr->e_type = xdr->get16(input);
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ehdr->e_machine = xdr->get16(input);
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ehdr->e_version = xdr->get32(input);
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if (bit64){
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ehdr->e_entry = xdr->get64(input);
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ehdr->e_phoff = xdr->get64(input);
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ehdr->e_shoff = xdr->get64(input);
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} else {
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ehdr->e_entry = xdr->get32(input);
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ehdr->e_phoff = xdr->get32(input);
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ehdr->e_shoff = xdr->get32(input);
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}
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ehdr->e_flags = xdr->get32(input);
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ehdr->e_ehsize = xdr->get16(input);
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ehdr->e_phentsize = xdr->get16(input);
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ehdr->e_phnum = xdr->get16(input);
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ehdr->e_shentsize = xdr->get16(input);
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ehdr->e_shnum = xdr->get16(input);
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ehdr->e_shstrndx = xdr->get16(input);
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}
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static void
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elf_phdr(struct buffer *pinput, Elf64_Phdr *phdr,
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int entsize, struct xdr *xdr, int bit64)
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{
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/*
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* The entsize need not be sizeof(*phdr).
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* Hence, it is easier to keep a copy of the input,
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* as the xdr functions may not advance the input
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* pointer the full entsize; rather than get tricky
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* we just advance it below.
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*/
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2014-03-05 05:08:05 +01:00
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struct buffer input;
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buffer_clone(&input, pinput);
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2013-12-30 22:16:18 +01:00
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if (bit64){
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phdr->p_type = xdr->get32(&input);
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phdr->p_flags = xdr->get32(&input);
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phdr->p_offset = xdr->get64(&input);
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phdr->p_vaddr = xdr->get64(&input);
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phdr->p_paddr = xdr->get64(&input);
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phdr->p_filesz = xdr->get64(&input);
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phdr->p_memsz = xdr->get64(&input);
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phdr->p_align = xdr->get64(&input);
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} else {
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phdr->p_type = xdr->get32(&input);
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phdr->p_offset = xdr->get32(&input);
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phdr->p_vaddr = xdr->get32(&input);
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phdr->p_paddr = xdr->get32(&input);
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phdr->p_filesz = xdr->get32(&input);
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phdr->p_memsz = xdr->get32(&input);
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phdr->p_flags = xdr->get32(&input);
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phdr->p_align = xdr->get32(&input);
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}
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2014-03-05 05:08:05 +01:00
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buffer_seek(pinput, entsize);
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2013-12-30 22:16:18 +01:00
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}
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static void
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elf_shdr(struct buffer *pinput, Elf64_Shdr *shdr,
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int entsize, struct xdr *xdr, int bit64)
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{
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/*
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* The entsize need not be sizeof(*shdr).
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* Hence, it is easier to keep a copy of the input,
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* as the xdr functions may not advance the input
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* pointer the full entsize; rather than get tricky
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* we just advance it below.
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*/
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struct buffer input = *pinput;
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if (bit64){
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shdr->sh_name = xdr->get32(&input);
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shdr->sh_type = xdr->get32(&input);
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shdr->sh_flags = xdr->get64(&input);
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shdr->sh_addr = xdr->get64(&input);
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shdr->sh_offset = xdr->get64(&input);
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shdr->sh_size= xdr->get64(&input);
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shdr->sh_link = xdr->get32(&input);
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shdr->sh_info = xdr->get32(&input);
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shdr->sh_addralign = xdr->get64(&input);
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shdr->sh_entsize = xdr->get64(&input);
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} else {
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shdr->sh_name = xdr->get32(&input);
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shdr->sh_type = xdr->get32(&input);
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shdr->sh_flags = xdr->get32(&input);
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shdr->sh_addr = xdr->get32(&input);
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shdr->sh_offset = xdr->get32(&input);
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shdr->sh_size = xdr->get32(&input);
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shdr->sh_link = xdr->get32(&input);
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shdr->sh_info = xdr->get32(&input);
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shdr->sh_addralign = xdr->get32(&input);
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shdr->sh_entsize = xdr->get32(&input);
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}
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2014-03-05 05:08:05 +01:00
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buffer_seek(pinput, entsize);
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}
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2014-03-05 20:09:55 +01:00
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static int
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phdr_read(const struct buffer *in, struct parsed_elf *pelf,
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struct xdr *xdr, int bit64)
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2014-03-05 05:08:05 +01:00
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{
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struct buffer b;
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Elf64_Phdr *phdr;
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2014-03-05 20:09:55 +01:00
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Elf64_Ehdr *ehdr;
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2014-03-05 05:08:05 +01:00
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int i;
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2014-03-05 20:09:55 +01:00
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ehdr = &pelf->ehdr;
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2014-03-05 05:08:05 +01:00
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/* cons up an input buffer for the headers.
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* Note that the program headers can be anywhere,
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* per the ELF spec, You'd be surprised how many ELF
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* readers miss this little detail.
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*/
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buffer_splice(&b, in, ehdr->e_phoff, ehdr->e_phentsize * ehdr->e_phnum);
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if (check_size(in, ehdr->e_phoff, buffer_size(&b), "program headers"))
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2014-03-05 20:09:55 +01:00
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return -1;
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2014-03-05 05:08:05 +01:00
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/* gather up all the phdrs.
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* We do them all at once because there is more
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* than one loop over all the phdrs.
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*/
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2014-03-05 21:54:13 +01:00
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phdr = calloc(ehdr->e_phnum, sizeof(*phdr));
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2014-03-07 22:23:05 +01:00
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for (i = 0; i < ehdr->e_phnum; i++) {
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DEBUG("Parsing segment %d\n", i);
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2014-03-05 05:08:05 +01:00
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elf_phdr(&b, &phdr[i], ehdr->e_phentsize, xdr, bit64);
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2014-03-07 22:23:05 +01:00
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/* Ensure the contents are valid within the elf file. */
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if (check_size(in, phdr[i].p_offset, phdr[i].p_filesz,
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2014-08-09 16:58:00 +02:00
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"segment contents")) {
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free(phdr);
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2014-03-05 20:09:55 +01:00
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return -1;
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2014-08-09 16:58:00 +02:00
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}
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2014-03-07 22:23:05 +01:00
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}
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2014-03-05 20:09:55 +01:00
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pelf->phdr = phdr;
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return 0;
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2014-03-05 05:08:05 +01:00
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}
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2014-03-05 20:09:55 +01:00
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static int
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shdr_read(const struct buffer *in, struct parsed_elf *pelf,
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struct xdr *xdr, int bit64)
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2014-03-05 05:08:05 +01:00
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{
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struct buffer b;
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Elf64_Shdr *shdr;
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2014-03-05 20:09:55 +01:00
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Elf64_Ehdr *ehdr;
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2014-03-05 05:08:05 +01:00
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int i;
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2014-03-05 20:09:55 +01:00
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ehdr = &pelf->ehdr;
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2014-03-05 05:08:05 +01:00
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/* cons up an input buffer for the section headers.
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* Note that the section headers can be anywhere,
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|
|
* per the ELF spec, You'd be surprised how many ELF
|
|
|
|
* readers miss this little detail.
|
|
|
|
*/
|
|
|
|
buffer_splice(&b, in, ehdr->e_shoff, ehdr->e_shentsize * ehdr->e_shnum);
|
|
|
|
if (check_size(in, ehdr->e_shoff, buffer_size(&b), "section headers"))
|
2014-03-05 20:09:55 +01:00
|
|
|
return -1;
|
2014-03-05 05:08:05 +01:00
|
|
|
|
|
|
|
/* gather up all the shdrs. */
|
2014-03-05 21:54:13 +01:00
|
|
|
shdr = calloc(ehdr->e_shnum, sizeof(*shdr));
|
2014-03-07 22:23:05 +01:00
|
|
|
for (i = 0; i < ehdr->e_shnum; i++) {
|
|
|
|
DEBUG("Parsing section %d\n", i);
|
2014-03-05 05:08:05 +01:00
|
|
|
elf_shdr(&b, &shdr[i], ehdr->e_shentsize, xdr, bit64);
|
2014-03-07 22:23:05 +01:00
|
|
|
}
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
pelf->shdr = shdr;
|
|
|
|
|
|
|
|
return 0;
|
2013-12-30 22:16:18 +01:00
|
|
|
}
|
|
|
|
|
2014-03-05 20:57:30 +01:00
|
|
|
static int
|
|
|
|
reloc_read(const struct buffer *in, struct parsed_elf *pelf,
|
|
|
|
struct xdr *xdr, int bit64)
|
|
|
|
{
|
|
|
|
struct buffer b;
|
|
|
|
Elf64_Word i;
|
|
|
|
Elf64_Ehdr *ehdr;
|
|
|
|
|
|
|
|
ehdr = &pelf->ehdr;
|
|
|
|
pelf->relocs = calloc(ehdr->e_shnum, sizeof(Elf64_Rela *));
|
|
|
|
|
|
|
|
/* Allocate array for each section that contains relocation entries. */
|
|
|
|
for (i = 0; i < ehdr->e_shnum; i++) {
|
|
|
|
Elf64_Shdr *shdr;
|
|
|
|
Elf64_Rela *rela;
|
|
|
|
Elf64_Xword j;
|
|
|
|
Elf64_Xword nrelocs;
|
|
|
|
int is_rela;
|
|
|
|
|
|
|
|
shdr = &pelf->shdr[i];
|
|
|
|
|
|
|
|
/* Only process REL and RELA sections. */
|
|
|
|
if (shdr->sh_type != SHT_REL && shdr->sh_type != SHT_RELA)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
DEBUG("Checking relocation section %u\n", i);
|
|
|
|
|
|
|
|
/* Ensure the section that relocations apply is a valid. */
|
|
|
|
if (shdr->sh_info >= ehdr->e_shnum ||
|
|
|
|
shdr->sh_info == SHN_UNDEF) {
|
|
|
|
ERROR("Relocations apply to an invalid section: %u\n",
|
|
|
|
shdr[i].sh_info);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
is_rela = shdr->sh_type == SHT_RELA;
|
|
|
|
|
|
|
|
/* Determine the number relocations in this section. */
|
|
|
|
nrelocs = shdr->sh_size / shdr->sh_entsize;
|
|
|
|
|
|
|
|
pelf->relocs[i] = calloc(nrelocs, sizeof(Elf64_Rela));
|
|
|
|
|
|
|
|
buffer_splice(&b, in, shdr->sh_offset, shdr->sh_size);
|
|
|
|
if (check_size(in, shdr->sh_offset, buffer_size(&b),
|
|
|
|
"relocation section")) {
|
|
|
|
ERROR("Relocation section %u failed.\n", i);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
rela = pelf->relocs[i];
|
|
|
|
for (j = 0; j < nrelocs; j++) {
|
|
|
|
if (bit64) {
|
|
|
|
rela->r_offset = xdr->get64(&b);
|
|
|
|
rela->r_info = xdr->get64(&b);
|
|
|
|
if (is_rela)
|
|
|
|
rela->r_addend = xdr->get64(&b);
|
|
|
|
} else {
|
|
|
|
uint32_t r_info;
|
|
|
|
|
|
|
|
rela->r_offset = xdr->get32(&b);
|
|
|
|
r_info = xdr->get32(&b);
|
|
|
|
rela->r_info = ELF64_R_INFO(ELF32_R_SYM(r_info),
|
|
|
|
ELF32_R_TYPE(r_info));
|
|
|
|
if (is_rela)
|
|
|
|
rela->r_addend = xdr->get32(&b);
|
|
|
|
}
|
|
|
|
rela++;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2014-03-05 21:33:42 +01:00
|
|
|
static int strtab_read(const struct buffer *in, struct parsed_elf *pelf)
|
|
|
|
{
|
|
|
|
Elf64_Ehdr *ehdr;
|
|
|
|
Elf64_Word i;
|
|
|
|
|
|
|
|
ehdr = &pelf->ehdr;
|
|
|
|
|
|
|
|
if (ehdr->e_shstrndx >= ehdr->e_shnum) {
|
|
|
|
ERROR("Section header string table index out of range: %d\n",
|
|
|
|
ehdr->e_shstrndx);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* For each section of type SHT_STRTAB create a symtab buffer. */
|
|
|
|
pelf->strtabs = calloc(ehdr->e_shnum, sizeof(struct buffer *));
|
|
|
|
|
|
|
|
for (i = 0; i < ehdr->e_shnum; i++) {
|
|
|
|
struct buffer *b;
|
|
|
|
Elf64_Shdr *shdr = &pelf->shdr[i];
|
|
|
|
|
|
|
|
if (shdr->sh_type != SHT_STRTAB)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
b = calloc(1, sizeof(*b));
|
|
|
|
buffer_splice(b, in, shdr->sh_offset, shdr->sh_size);
|
|
|
|
if (check_size(in, shdr->sh_offset, buffer_size(b), "strtab")) {
|
|
|
|
ERROR("STRTAB section not within bounds: %d\n", i);
|
2014-08-09 16:58:00 +02:00
|
|
|
free(b);
|
2014-03-05 21:33:42 +01:00
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
pelf->strtabs[i] = b;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2014-03-05 23:41:27 +01:00
|
|
|
static int
|
|
|
|
symtab_read(const struct buffer *in, struct parsed_elf *pelf,
|
|
|
|
struct xdr *xdr, int bit64)
|
|
|
|
{
|
|
|
|
Elf64_Ehdr *ehdr;
|
|
|
|
Elf64_Shdr *shdr;
|
|
|
|
Elf64_Half i;
|
|
|
|
Elf64_Xword nsyms;
|
|
|
|
Elf64_Sym *sym;
|
|
|
|
struct buffer b;
|
|
|
|
|
|
|
|
ehdr = &pelf->ehdr;
|
|
|
|
|
|
|
|
shdr = NULL;
|
|
|
|
for (i = 0; i < ehdr->e_shnum; i++) {
|
|
|
|
if (pelf->shdr[i].sh_type != SHT_SYMTAB)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
if (shdr != NULL) {
|
|
|
|
ERROR("Multiple symbol sections found. %u and %u\n",
|
|
|
|
(unsigned int)(shdr - pelf->shdr), i);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
shdr = &pelf->shdr[i];
|
|
|
|
}
|
|
|
|
|
|
|
|
if (shdr == NULL) {
|
|
|
|
ERROR("No symbol table found.\n");
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
buffer_splice(&b, in, shdr->sh_offset, shdr->sh_size);
|
|
|
|
if (check_size(in, shdr->sh_offset, buffer_size(&b), "symtab"))
|
|
|
|
return -1;
|
|
|
|
|
|
|
|
nsyms = shdr->sh_size / shdr->sh_entsize;
|
|
|
|
|
|
|
|
pelf->syms = calloc(nsyms, sizeof(Elf64_Sym));
|
|
|
|
|
|
|
|
for (i = 0; i < nsyms; i++) {
|
|
|
|
sym = &pelf->syms[i];
|
|
|
|
|
|
|
|
if (bit64) {
|
|
|
|
sym->st_name = xdr->get32(&b);
|
|
|
|
sym->st_info = xdr->get8(&b);
|
|
|
|
sym->st_other = xdr->get8(&b);
|
|
|
|
sym->st_shndx = xdr->get16(&b);
|
|
|
|
sym->st_value = xdr->get64(&b);
|
|
|
|
sym->st_size = xdr->get64(&b);
|
|
|
|
} else {
|
|
|
|
sym->st_name = xdr->get32(&b);
|
|
|
|
sym->st_value = xdr->get32(&b);
|
|
|
|
sym->st_size = xdr->get32(&b);
|
|
|
|
sym->st_info = xdr->get8(&b);
|
|
|
|
sym->st_other = xdr->get8(&b);
|
|
|
|
sym->st_shndx = xdr->get16(&b);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags)
|
2013-12-30 22:16:18 +01:00
|
|
|
{
|
|
|
|
struct xdr *xdr = &xdr_le;
|
|
|
|
int bit64 = 0;
|
2014-03-05 05:08:05 +01:00
|
|
|
struct buffer input;
|
2014-03-05 20:09:55 +01:00
|
|
|
Elf64_Ehdr *ehdr;
|
2014-03-05 05:08:05 +01:00
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
/* Zero out the parsed elf structure. */
|
|
|
|
memset(pelf, 0, sizeof(*pelf));
|
2013-12-30 22:16:18 +01:00
|
|
|
|
2014-03-05 05:08:05 +01:00
|
|
|
if (!iself(buffer_get(pinput))) {
|
2013-12-30 22:16:18 +01:00
|
|
|
ERROR("The stage file is not in ELF format!\n");
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
buffer_clone(&input, pinput);
|
|
|
|
ehdr = &pelf->ehdr;
|
2013-12-30 22:16:18 +01:00
|
|
|
elf_eident(&input, ehdr);
|
|
|
|
bit64 = ehdr->e_ident[EI_CLASS] == ELFCLASS64;
|
|
|
|
/* Assume LE unless we are sure otherwise.
|
|
|
|
* We're not going to take on the task of
|
|
|
|
* fully validating the ELF file. That way
|
|
|
|
* lies madness.
|
|
|
|
*/
|
|
|
|
if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
|
|
|
|
xdr = &xdr_be;
|
|
|
|
|
|
|
|
elf_ehdr(&input, ehdr, xdr, bit64);
|
|
|
|
|
2014-03-05 20:57:30 +01:00
|
|
|
/* Relocation processing requires section header parsing. */
|
|
|
|
if (flags & ELF_PARSE_RELOC)
|
|
|
|
flags |= ELF_PARSE_SHDR;
|
|
|
|
|
2014-03-05 21:33:42 +01:00
|
|
|
/* String table processing requires section header parsing. */
|
|
|
|
if (flags & ELF_PARSE_STRTAB)
|
|
|
|
flags |= ELF_PARSE_SHDR;
|
|
|
|
|
2014-03-05 23:41:27 +01:00
|
|
|
/* Symbole table processing requires section header parsing. */
|
|
|
|
if (flags & ELF_PARSE_SYMTAB)
|
|
|
|
flags |= ELF_PARSE_SHDR;
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
if ((flags & ELF_PARSE_PHDR) && phdr_read(pinput, pelf, xdr, bit64))
|
|
|
|
goto fail;
|
|
|
|
|
|
|
|
if ((flags & ELF_PARSE_SHDR) && shdr_read(pinput, pelf, xdr, bit64))
|
|
|
|
goto fail;
|
|
|
|
|
2014-03-05 20:57:30 +01:00
|
|
|
if ((flags & ELF_PARSE_RELOC) && reloc_read(pinput, pelf, xdr, bit64))
|
|
|
|
goto fail;
|
|
|
|
|
2014-03-05 21:33:42 +01:00
|
|
|
if ((flags & ELF_PARSE_STRTAB) && strtab_read(pinput, pelf))
|
|
|
|
goto fail;
|
|
|
|
|
2014-03-05 23:41:27 +01:00
|
|
|
if ((flags & ELF_PARSE_SYMTAB) && symtab_read(pinput, pelf, xdr, bit64))
|
|
|
|
goto fail;
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
return 0;
|
|
|
|
|
|
|
|
fail:
|
|
|
|
parsed_elf_destroy(pelf);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
void parsed_elf_destroy(struct parsed_elf *pelf)
|
|
|
|
{
|
2014-03-05 21:33:42 +01:00
|
|
|
Elf64_Half i;
|
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
free(pelf->phdr);
|
|
|
|
free(pelf->shdr);
|
2014-03-05 20:57:30 +01:00
|
|
|
if (pelf->relocs != NULL) {
|
|
|
|
for (i = 0; i < pelf->ehdr.e_shnum; i++)
|
|
|
|
free(pelf->relocs[i]);
|
|
|
|
}
|
|
|
|
free(pelf->relocs);
|
2014-03-05 21:33:42 +01:00
|
|
|
|
|
|
|
if (pelf->strtabs != NULL) {
|
|
|
|
for (i = 0; i < pelf->ehdr.e_shnum; i++)
|
|
|
|
free(pelf->strtabs[i]);
|
|
|
|
}
|
|
|
|
free(pelf->strtabs);
|
2014-03-05 23:41:27 +01:00
|
|
|
free(pelf->syms);
|
2014-03-05 20:09:55 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
/* Get the headers from the buffer.
|
|
|
|
* Return -1 in the event of an error.
|
|
|
|
* The section headers are optional; if NULL
|
|
|
|
* is passed in for pshdr they won't be parsed.
|
|
|
|
* We don't (yet) make payload parsing optional
|
|
|
|
* because we've never seen a use case.
|
|
|
|
*/
|
|
|
|
int
|
|
|
|
elf_headers(const struct buffer *pinput,
|
|
|
|
Elf64_Ehdr *ehdr,
|
|
|
|
Elf64_Phdr **pphdr,
|
|
|
|
Elf64_Shdr **pshdr)
|
|
|
|
{
|
|
|
|
struct parsed_elf pelf;
|
|
|
|
int flags;
|
|
|
|
|
|
|
|
flags = ELF_PARSE_PHDR;
|
|
|
|
|
|
|
|
if (pshdr != NULL)
|
|
|
|
flags |= ELF_PARSE_SHDR;
|
|
|
|
|
|
|
|
if (parse_elf(pinput, &pelf, flags))
|
|
|
|
return -1;
|
|
|
|
|
|
|
|
/* Copy out the parsed elf header. */
|
|
|
|
memcpy(ehdr, &pelf.ehdr, sizeof(*ehdr));
|
|
|
|
|
|
|
|
*pphdr = calloc(ehdr->e_phnum, sizeof(Elf64_Phdr));
|
|
|
|
memcpy(*pphdr, pelf.phdr, ehdr->e_phnum * sizeof(Elf64_Phdr));
|
2013-12-30 22:16:18 +01:00
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
if (pshdr != NULL) {
|
|
|
|
*pshdr = calloc(ehdr->e_shnum, sizeof(Elf64_Shdr));
|
|
|
|
memcpy(*pshdr, pelf.shdr, ehdr->e_shnum * sizeof(Elf64_Shdr));
|
|
|
|
}
|
2013-12-30 22:16:18 +01:00
|
|
|
|
2014-03-05 20:09:55 +01:00
|
|
|
parsed_elf_destroy(&pelf);
|
2013-12-30 22:16:18 +01:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
2014-03-11 17:48:56 +01:00
|
|
|
|
|
|
|
/* ELF Writing Support
|
|
|
|
*
|
|
|
|
* The ELF file is written according to the following layout:
|
|
|
|
* +------------------+
|
|
|
|
* | ELF Header |
|
|
|
|
* +------------------+
|
|
|
|
* | Section Headers |
|
|
|
|
* +------------------+
|
|
|
|
* | Program Headers |
|
|
|
|
* +------------------+
|
|
|
|
* | String table |
|
|
|
|
* +------------------+ <- 4KiB Aligned
|
|
|
|
* | Code/Data |
|
|
|
|
* +------------------+
|
|
|
|
*/
|
|
|
|
|
|
|
|
/* Arbitray maximum number of sections. */
|
|
|
|
#define MAX_SECTIONS 16
|
|
|
|
struct elf_writer_section {
|
|
|
|
Elf64_Shdr shdr;
|
|
|
|
struct buffer content;
|
|
|
|
const char *name;
|
|
|
|
};
|
|
|
|
|
|
|
|
struct elf_writer
|
|
|
|
{
|
|
|
|
Elf64_Ehdr ehdr;
|
|
|
|
struct xdr *xdr;
|
|
|
|
size_t num_secs;
|
|
|
|
struct elf_writer_section sections[MAX_SECTIONS];
|
|
|
|
Elf64_Phdr *phdrs;
|
|
|
|
struct elf_writer_section *shstrtab;
|
|
|
|
int bit64;
|
|
|
|
};
|
|
|
|
|
|
|
|
struct elf_writer *elf_writer_init(const Elf64_Ehdr *ehdr)
|
|
|
|
{
|
|
|
|
struct elf_writer *ew;
|
|
|
|
Elf64_Shdr shdr;
|
|
|
|
struct buffer empty_buffer;
|
|
|
|
|
|
|
|
if (!iself(ehdr))
|
|
|
|
return NULL;
|
|
|
|
|
|
|
|
ew = calloc(1, sizeof(*ew));
|
|
|
|
|
|
|
|
memcpy(&ew->ehdr, ehdr, sizeof(ew->ehdr));
|
|
|
|
|
|
|
|
ew->bit64 = ew->ehdr.e_ident[EI_CLASS] == ELFCLASS64;
|
|
|
|
|
|
|
|
/* Set the endinan ops. */
|
|
|
|
if (ew->ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
|
|
|
|
ew->xdr = &xdr_be;
|
|
|
|
else
|
|
|
|
ew->xdr = &xdr_le;
|
|
|
|
|
|
|
|
/* Reset count and offsets */
|
|
|
|
ew->ehdr.e_phoff = 0;
|
|
|
|
ew->ehdr.e_shoff = 0;
|
|
|
|
ew->ehdr.e_shnum = 0;
|
|
|
|
ew->ehdr.e_phnum = 0;
|
|
|
|
|
|
|
|
memset(&empty_buffer, 0, sizeof(empty_buffer));
|
|
|
|
memset(&shdr, 0, sizeof(shdr));
|
|
|
|
|
|
|
|
/* Add SHT_NULL section header. */
|
|
|
|
shdr.sh_type = SHT_NULL;
|
|
|
|
elf_writer_add_section(ew, &shdr, &empty_buffer, NULL);
|
|
|
|
|
|
|
|
/* Add section header string table and maintain reference to it. */
|
|
|
|
shdr.sh_type = SHT_STRTAB;
|
|
|
|
elf_writer_add_section(ew, &shdr, &empty_buffer, ".shstrtab");
|
|
|
|
ew->ehdr.e_shstrndx = ew->num_secs - 1;
|
|
|
|
ew->shstrtab = &ew->sections[ew->ehdr.e_shstrndx];
|
|
|
|
|
|
|
|
return ew;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Clean up any internal state represented by ew. Aftewards the elf_writer
|
|
|
|
* is invalid.
|
|
|
|
*/
|
|
|
|
void elf_writer_destroy(struct elf_writer *ew)
|
|
|
|
{
|
|
|
|
if (ew->phdrs != NULL)
|
|
|
|
free(ew->phdrs);
|
|
|
|
free(ew);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Add a section to the ELF file. Section type, flags, and memsize are
|
|
|
|
* maintained from the passed in Elf64_Shdr. The buffer represents the
|
|
|
|
* content of the section while the name is the name of section itself.
|
|
|
|
* Returns < 0 on error, 0 on success.
|
|
|
|
*/
|
|
|
|
int elf_writer_add_section(struct elf_writer *ew, const Elf64_Shdr *shdr,
|
|
|
|
struct buffer *contents, const char *name)
|
|
|
|
{
|
|
|
|
struct elf_writer_section *newsh;
|
|
|
|
|
|
|
|
if (ew->num_secs == MAX_SECTIONS)
|
|
|
|
return -1;
|
|
|
|
|
|
|
|
newsh = &ew->sections[ew->num_secs];
|
|
|
|
ew->num_secs++;
|
|
|
|
|
|
|
|
memcpy(&newsh->shdr, shdr, sizeof(newsh->shdr));
|
|
|
|
newsh->shdr.sh_offset = 0;
|
|
|
|
|
|
|
|
newsh->name = name;
|
|
|
|
if (contents != NULL)
|
|
|
|
buffer_clone(&newsh->content, contents);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void ehdr_write(struct elf_writer *ew, struct buffer *m)
|
|
|
|
{
|
|
|
|
int i;
|
|
|
|
|
|
|
|
for (i = 0; i < EI_NIDENT; i++)
|
|
|
|
ew->xdr->put8(m, ew->ehdr.e_ident[i]);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_type);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_machine);
|
|
|
|
ew->xdr->put32(m, ew->ehdr.e_version);
|
|
|
|
if (ew->bit64) {
|
|
|
|
ew->xdr->put64(m, ew->ehdr.e_entry);
|
|
|
|
ew->xdr->put64(m, ew->ehdr.e_phoff);
|
|
|
|
ew->xdr->put64(m, ew->ehdr.e_shoff);
|
|
|
|
} else {
|
|
|
|
ew->xdr->put32(m, ew->ehdr.e_entry);
|
|
|
|
ew->xdr->put32(m, ew->ehdr.e_phoff);
|
|
|
|
ew->xdr->put32(m, ew->ehdr.e_shoff);
|
|
|
|
}
|
|
|
|
ew->xdr->put32(m, ew->ehdr.e_flags);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_ehsize);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_phentsize);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_phnum);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_shentsize);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_shnum);
|
|
|
|
ew->xdr->put16(m, ew->ehdr.e_shstrndx);
|
|
|
|
}
|
|
|
|
|
|
|
|
static void shdr_write(struct elf_writer *ew, size_t n, struct buffer *m)
|
|
|
|
{
|
|
|
|
struct xdr *xdr = ew->xdr;
|
|
|
|
int bit64 = ew->bit64;
|
|
|
|
struct elf_writer_section *sec = &ew->sections[n];
|
|
|
|
Elf64_Shdr *shdr = &sec->shdr;
|
|
|
|
|
|
|
|
xdr->put32(m, shdr->sh_name);
|
|
|
|
xdr->put32(m, shdr->sh_type);
|
|
|
|
if (bit64) {
|
2014-08-22 21:05:00 +02:00
|
|
|
xdr->put64(m, shdr->sh_flags);
|
2014-03-11 17:48:56 +01:00
|
|
|
xdr->put64(m, shdr->sh_addr);
|
|
|
|
xdr->put64(m, shdr->sh_offset);
|
|
|
|
xdr->put64(m, shdr->sh_size);
|
|
|
|
xdr->put32(m, shdr->sh_link);
|
|
|
|
xdr->put32(m, shdr->sh_info);
|
|
|
|
xdr->put64(m, shdr->sh_addralign);
|
|
|
|
xdr->put64(m, shdr->sh_entsize);
|
|
|
|
} else {
|
2014-08-22 21:05:00 +02:00
|
|
|
xdr->put32(m, shdr->sh_flags);
|
2014-03-11 17:48:56 +01:00
|
|
|
xdr->put32(m, shdr->sh_addr);
|
|
|
|
xdr->put32(m, shdr->sh_offset);
|
|
|
|
xdr->put32(m, shdr->sh_size);
|
|
|
|
xdr->put32(m, shdr->sh_link);
|
|
|
|
xdr->put32(m, shdr->sh_info);
|
|
|
|
xdr->put32(m, shdr->sh_addralign);
|
|
|
|
xdr->put32(m, shdr->sh_entsize);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
|
|
phdr_write(struct elf_writer *ew, struct buffer *m, Elf64_Phdr *phdr)
|
|
|
|
{
|
|
|
|
if (ew->bit64) {
|
|
|
|
ew->xdr->put32(m, phdr->p_type);
|
|
|
|
ew->xdr->put32(m, phdr->p_flags);
|
|
|
|
ew->xdr->put64(m, phdr->p_offset);
|
|
|
|
ew->xdr->put64(m, phdr->p_vaddr);
|
|
|
|
ew->xdr->put64(m, phdr->p_paddr);
|
|
|
|
ew->xdr->put64(m, phdr->p_filesz);
|
|
|
|
ew->xdr->put64(m, phdr->p_memsz);
|
|
|
|
ew->xdr->put64(m, phdr->p_align);
|
|
|
|
} else {
|
|
|
|
ew->xdr->put32(m, phdr->p_type);
|
|
|
|
ew->xdr->put32(m, phdr->p_offset);
|
|
|
|
ew->xdr->put32(m, phdr->p_vaddr);
|
|
|
|
ew->xdr->put32(m, phdr->p_paddr);
|
|
|
|
ew->xdr->put32(m, phdr->p_filesz);
|
|
|
|
ew->xdr->put32(m, phdr->p_memsz);
|
|
|
|
ew->xdr->put32(m, phdr->p_flags);
|
|
|
|
ew->xdr->put32(m, phdr->p_align);
|
|
|
|
}
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Serialize the ELF file to the output buffer. Return < 0 on error,
|
|
|
|
* 0 on success.
|
|
|
|
*/
|
|
|
|
int elf_writer_serialize(struct elf_writer *ew, struct buffer *out)
|
|
|
|
{
|
|
|
|
Elf64_Half i;
|
|
|
|
Elf64_Xword metadata_size;
|
|
|
|
Elf64_Xword program_size;
|
|
|
|
Elf64_Off shstroffset;
|
|
|
|
size_t shstrlen;
|
|
|
|
struct buffer metadata;
|
|
|
|
struct buffer phdrs;
|
|
|
|
struct buffer data;
|
|
|
|
struct buffer *strtab;
|
|
|
|
|
|
|
|
INFO("Writing %zu sections.\n", ew->num_secs);
|
|
|
|
|
|
|
|
/* Determine size of sections to be written. */
|
|
|
|
program_size = 0;
|
|
|
|
/* Start with 1 byte for first byte of section header string table. */
|
|
|
|
shstrlen = 1;
|
|
|
|
for (i = 0; i < ew->num_secs; i++) {
|
|
|
|
struct elf_writer_section *sec = &ew->sections[i];
|
|
|
|
|
|
|
|
if (sec->shdr.sh_flags & SHF_ALLOC)
|
|
|
|
ew->ehdr.e_phnum++;
|
|
|
|
|
|
|
|
program_size += buffer_size(&sec->content);
|
|
|
|
|
|
|
|
/* Keep track of the length sections' names. */
|
|
|
|
if (sec->name != NULL) {
|
|
|
|
sec->shdr.sh_name = shstrlen;
|
|
|
|
shstrlen += strlen(sec->name) + 1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
ew->ehdr.e_shnum = ew->num_secs;
|
|
|
|
metadata_size = 0;
|
|
|
|
metadata_size += ew->ehdr.e_ehsize;
|
|
|
|
metadata_size += ew->ehdr.e_shnum * ew->ehdr.e_shentsize;
|
|
|
|
metadata_size += ew->ehdr.e_phnum * ew->ehdr.e_phentsize;
|
|
|
|
shstroffset = metadata_size;
|
|
|
|
/* Align up section header string size and metadata size to 4KiB */
|
|
|
|
metadata_size = ALIGN(metadata_size + shstrlen, 4096);
|
|
|
|
|
|
|
|
if (buffer_create(out, metadata_size + program_size, "elfout")) {
|
|
|
|
ERROR("Could not create output buffer for ELF.\n");
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
INFO("Created %zu output buffer for ELF file.\n", buffer_size(out));
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Write out ELF header. Section headers come right after ELF header
|
|
|
|
* followed by the program headers. Buffers need to be created first
|
|
|
|
* to do the writing.
|
|
|
|
*/
|
|
|
|
ew->ehdr.e_shoff = ew->ehdr.e_ehsize;
|
|
|
|
ew->ehdr.e_phoff = ew->ehdr.e_shoff +
|
|
|
|
ew->ehdr.e_shnum * ew->ehdr.e_shentsize;
|
|
|
|
|
|
|
|
buffer_splice(&metadata, out, 0, metadata_size);
|
|
|
|
buffer_splice(&phdrs, out, ew->ehdr.e_phoff,
|
|
|
|
ew->ehdr.e_phnum * ew->ehdr.e_phentsize);
|
|
|
|
buffer_splice(&data, out, metadata_size, program_size);
|
|
|
|
/* Set up the section header string table contents. */
|
|
|
|
strtab = &ew->shstrtab->content;
|
|
|
|
buffer_splice(strtab, out, shstroffset, shstrlen);
|
|
|
|
ew->shstrtab->shdr.sh_size = shstrlen;
|
|
|
|
|
|
|
|
/* Reset current locations. */
|
|
|
|
buffer_set_size(&metadata, 0);
|
|
|
|
buffer_set_size(&data, 0);
|
|
|
|
buffer_set_size(&phdrs, 0);
|
|
|
|
buffer_set_size(strtab, 0);
|
|
|
|
|
|
|
|
/* ELF Header */
|
|
|
|
ehdr_write(ew, &metadata);
|
|
|
|
|
|
|
|
/* Write out section headers, section strings, section content, and
|
|
|
|
* program headers. */
|
|
|
|
ew->xdr->put8(strtab, 0);
|
|
|
|
for (i = 0; i < ew->num_secs; i++) {
|
|
|
|
Elf64_Phdr phdr;
|
|
|
|
struct elf_writer_section *sec = &ew->sections[i];
|
|
|
|
|
|
|
|
/* Update section offsets. Be sure to not update SHT_NULL. */
|
|
|
|
if (sec == ew->shstrtab)
|
|
|
|
sec->shdr.sh_offset = shstroffset;
|
|
|
|
else if (i != 0)
|
|
|
|
sec->shdr.sh_offset = buffer_size(&data) +
|
|
|
|
metadata_size;
|
|
|
|
shdr_write(ew, i, &metadata);
|
|
|
|
|
|
|
|
/* Add section name to string table. */
|
|
|
|
if (sec->name != NULL)
|
|
|
|
bputs(strtab, sec->name, strlen(sec->name) + 1);
|
|
|
|
|
|
|
|
if (!(sec->shdr.sh_flags & SHF_ALLOC))
|
|
|
|
continue;
|
|
|
|
|
|
|
|
bputs(&data, buffer_get(&sec->content),
|
|
|
|
buffer_size(&sec->content));
|
|
|
|
|
|
|
|
phdr.p_type = PT_LOAD;
|
|
|
|
phdr.p_offset = sec->shdr.sh_offset;
|
|
|
|
phdr.p_vaddr = sec->shdr.sh_addr;
|
|
|
|
phdr.p_paddr = sec->shdr.sh_addr;
|
|
|
|
phdr.p_filesz = buffer_size(&sec->content);
|
|
|
|
phdr.p_memsz = sec->shdr.sh_size;
|
|
|
|
phdr.p_flags = 0;
|
|
|
|
if (sec->shdr.sh_flags & SHF_EXECINSTR)
|
|
|
|
phdr.p_flags |= PF_X | PF_R;
|
|
|
|
if (sec->shdr.sh_flags & SHF_WRITE)
|
|
|
|
phdr.p_flags |= PF_W;
|
|
|
|
phdr.p_align = sec->shdr.sh_addralign;
|
|
|
|
phdr_write(ew, &phdrs, &phdr);
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|