coreboot-kgpe-d16/util/cbfstool/elfheaders.c

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Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
/*
* elf header parsing.
*
* Copyright (C) 2013 Google, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "elfparsing.h"
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
#include "common.h"
#include "cbfs.h"
/*
* Short form: this is complicated, but we've tried making it simple
* and we keep hitting problems with our ELF parsing.
*
* The ELF parsing situation has always been a bit tricky. In fact,
* we (and most others) have been getting it wrong in small ways for
* years. Recently this has caused real trouble for the ARM V8 build.
* In this file we attempt to finally get it right for all variations
* of endian-ness and word size and target architectures and
* architectures we might get run on. Phew!. To do this we borrow a
* page from the FreeBSD NFS xdr model (see elf_ehdr and elf_phdr),
* the Plan 9 endianness functions (see xdr.c), and Go interfaces (see
* how we use buffer structs in this file). This ends up being a bit
* wordy at the lowest level, but greatly simplifies the elf parsing
* code and removes a common source of bugs, namely, forgetting to
* flip type endianness when referencing a struct member.
*
* ELF files can have four combinations of data layout: 32/64, and
* big/little endian. Further, to add to the fun, depending on the
* word size, the size of the ELF structs varies. The coreboot SELF
* format is simpler in theory: it's supposed to be always BE, and the
* various struct members allow room for growth: the entry point is
* always 64 bits, for example, so the size of a SELF struct is
* constant, regardless of target architecture word size. Hence, we
* need to do some transformation of the ELF files.
*
* A given architecture, realistically, only supports one of the four
* combinations at a time as the 'native' format. Hence, our code has
* been sprinkled with every variation of [nh]to[hn][sll] over the
* years. We've never quite gotten it all right, however, and a quick
* pass over this code revealed another bug. It's all worked because,
* until now, all the working platforms that had CBFS were 32 LE. Even then,
* however, bugs crept in: we recently realized that we're not
* transforming the entry point to big format when we store into the
* SELF image.
*
* The problem is essentially an XDR operation:
* we have something in a foreign format and need to transform it.
* It's most like XDR because:
* 1) the byte order can be wrong
* 2) the word size can be wrong
* 3) the size of elements in the stream depends on the value
* of other elements in the stream
* it's not like XDR because:
* 1) the byte order can be right
* 2) the word size can be right
* 3) the struct members are all on a natural alignment
*
* Hence, this new approach. To cover word size issues, we *always*
* transform the two structs we care about, the file header and
* program header, into a native struct in the 64 bit format:
*
* [32,little] -> [Elf64_Ehdr, Elf64_Phdr]
* [64,little] -> [Elf64_Ehdr, Elf64_Phdr]
* [32,big] -> [Elf64_Ehdr, Elf64_Phdr]
* [64,big] -> [Elf64_Ehdr, Elf64_Phdr]
* Then we just use those structs, and all the need for inline ntoh* goes away,
* as well as all the chances for error.
* This works because all the SELF structs have fields large enough for
* the largest ELF 64 struct members, and all the Elf64 struct members
* are at least large enough for all ELF 32 struct members.
* We end up with one function to do all our ELF parsing, and two functions
* to transform the headers. For the put case, we also have
* XDR functions, and hopefully we'll never again spend 5 years with the
* wrong endian-ness on an output value :-)
* This should work for all word sizes and endianness we hope to target.
* I *really* don't want to be here for 128 bit addresses.
*
* The parse functions are called with a pointer to an input buffer
* struct. One might ask: are there enough bytes in the input buffer?
* We know there need to be at *least* sizeof(Elf32_Ehdr) +
* sizeof(Elf32_Phdr) bytes. Realistically, there has to be some data
* too. If we start to worry, though we have not in the past, we
* might apply the simple test: the input buffer needs to be at least
* sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) bytes because, even if it's
* ELF 32, there's got to be *some* data! This is not theoretically
* accurate but it is actually good enough in practice. It allows the
* header transformation code to ignore the possibility of underrun.
*
* We also must accomodate different ELF files, and hence formats,
* in the same cbfs invocation. We might load a 64-bit payload
* on a 32-bit machine; we might even have a mixed armv7/armv8
* SOC or even a system with an x86/ARM!
*
* A possibly problematic (though unlikely to be so) assumption
* is that we expect the BIOS to remain in the lowest 32 bits
* of the physical address space. Since ARMV8 has standardized
* on that, and x86_64 also has, this seems a safe assumption.
*
* To repeat, ELF structs are different sizes because ELF struct
* members are different sizes, depending on values in the ELF file
* header. For this we use the functions defined in xdr.c, which
* consume bytes, convert the endianness, and advance the data pointer
* in the buffer struct.
*/
static int iself(const void *input)
{
const Elf32_Ehdr *ehdr = input;
return !memcmp(ehdr->e_ident, ELFMAG, 4);
}
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
/* Get the ident array, so we can figure out
* endian-ness, word size, and in future other useful
* parameters
*/
static void
elf_eident(struct buffer *input, Elf64_Ehdr *ehdr)
{
bgets(input, ehdr->e_ident, sizeof(ehdr->e_ident));
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
}
static int
check_size(const struct buffer *b, size_t offset, size_t size, const char *desc)
{
if (size == 0)
return 0;
if (offset >= buffer_size(b) || (offset + size) > buffer_size(b)) {
ERROR("The file is not large enough for the '%s'. "
"%zu bytes @ offset %zu, input %zu bytes.\n",
desc, size, offset, buffer_size(b));
return -1;
}
return 0;
}
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
static void
elf_ehdr(struct buffer *input, Elf64_Ehdr *ehdr, struct xdr *xdr, int bit64)
{
ehdr->e_type = xdr->get16(input);
ehdr->e_machine = xdr->get16(input);
ehdr->e_version = xdr->get32(input);
if (bit64){
ehdr->e_entry = xdr->get64(input);
ehdr->e_phoff = xdr->get64(input);
ehdr->e_shoff = xdr->get64(input);
} else {
ehdr->e_entry = xdr->get32(input);
ehdr->e_phoff = xdr->get32(input);
ehdr->e_shoff = xdr->get32(input);
}
ehdr->e_flags = xdr->get32(input);
ehdr->e_ehsize = xdr->get16(input);
ehdr->e_phentsize = xdr->get16(input);
ehdr->e_phnum = xdr->get16(input);
ehdr->e_shentsize = xdr->get16(input);
ehdr->e_shnum = xdr->get16(input);
ehdr->e_shstrndx = xdr->get16(input);
}
static void
elf_phdr(struct buffer *pinput, Elf64_Phdr *phdr,
int entsize, struct xdr *xdr, int bit64)
{
/*
* The entsize need not be sizeof(*phdr).
* Hence, it is easier to keep a copy of the input,
* as the xdr functions may not advance the input
* pointer the full entsize; rather than get tricky
* we just advance it below.
*/
struct buffer input;
buffer_clone(&input, pinput);
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
if (bit64){
phdr->p_type = xdr->get32(&input);
phdr->p_flags = xdr->get32(&input);
phdr->p_offset = xdr->get64(&input);
phdr->p_vaddr = xdr->get64(&input);
phdr->p_paddr = xdr->get64(&input);
phdr->p_filesz = xdr->get64(&input);
phdr->p_memsz = xdr->get64(&input);
phdr->p_align = xdr->get64(&input);
} else {
phdr->p_type = xdr->get32(&input);
phdr->p_offset = xdr->get32(&input);
phdr->p_vaddr = xdr->get32(&input);
phdr->p_paddr = xdr->get32(&input);
phdr->p_filesz = xdr->get32(&input);
phdr->p_memsz = xdr->get32(&input);
phdr->p_flags = xdr->get32(&input);
phdr->p_align = xdr->get32(&input);
}
buffer_seek(pinput, entsize);
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
}
static void
elf_shdr(struct buffer *pinput, Elf64_Shdr *shdr,
int entsize, struct xdr *xdr, int bit64)
{
/*
* The entsize need not be sizeof(*shdr).
* Hence, it is easier to keep a copy of the input,
* as the xdr functions may not advance the input
* pointer the full entsize; rather than get tricky
* we just advance it below.
*/
struct buffer input = *pinput;
if (bit64){
shdr->sh_name = xdr->get32(&input);
shdr->sh_type = xdr->get32(&input);
shdr->sh_flags = xdr->get64(&input);
shdr->sh_addr = xdr->get64(&input);
shdr->sh_offset = xdr->get64(&input);
shdr->sh_size= xdr->get64(&input);
shdr->sh_link = xdr->get32(&input);
shdr->sh_info = xdr->get32(&input);
shdr->sh_addralign = xdr->get64(&input);
shdr->sh_entsize = xdr->get64(&input);
} else {
shdr->sh_name = xdr->get32(&input);
shdr->sh_type = xdr->get32(&input);
shdr->sh_flags = xdr->get32(&input);
shdr->sh_addr = xdr->get32(&input);
shdr->sh_offset = xdr->get32(&input);
shdr->sh_size = xdr->get32(&input);
shdr->sh_link = xdr->get32(&input);
shdr->sh_info = xdr->get32(&input);
shdr->sh_addralign = xdr->get32(&input);
shdr->sh_entsize = xdr->get32(&input);
}
buffer_seek(pinput, entsize);
}
static int
phdr_read(const struct buffer *in, struct parsed_elf *pelf,
struct xdr *xdr, int bit64)
{
struct buffer b;
Elf64_Phdr *phdr;
Elf64_Ehdr *ehdr;
int i;
ehdr = &pelf->ehdr;
/* cons up an input buffer for the headers.
* Note that the program headers can be anywhere,
* per the ELF spec, You'd be surprised how many ELF
* readers miss this little detail.
*/
buffer_splice(&b, in, ehdr->e_phoff, ehdr->e_phentsize * ehdr->e_phnum);
if (check_size(in, ehdr->e_phoff, buffer_size(&b), "program headers"))
return -1;
/* gather up all the phdrs.
* We do them all at once because there is more
* than one loop over all the phdrs.
*/
phdr = calloc(ehdr->e_phnum, sizeof(*phdr));
for (i = 0; i < ehdr->e_phnum; i++) {
DEBUG("Parsing segment %d\n", i);
elf_phdr(&b, &phdr[i], ehdr->e_phentsize, xdr, bit64);
/* Ensure the contents are valid within the elf file. */
if (check_size(in, phdr[i].p_offset, phdr[i].p_filesz,
"segment contents")) {
free(phdr);
return -1;
}
}
pelf->phdr = phdr;
return 0;
}
static int
shdr_read(const struct buffer *in, struct parsed_elf *pelf,
struct xdr *xdr, int bit64)
{
struct buffer b;
Elf64_Shdr *shdr;
Elf64_Ehdr *ehdr;
int i;
ehdr = &pelf->ehdr;
/* cons up an input buffer for the section headers.
* Note that the section headers can be anywhere,
* 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"))
return -1;
/* gather up all the shdrs. */
shdr = calloc(ehdr->e_shnum, sizeof(*shdr));
for (i = 0; i < ehdr->e_shnum; i++) {
DEBUG("Parsing section %d\n", i);
elf_shdr(&b, &shdr[i], ehdr->e_shentsize, xdr, bit64);
}
pelf->shdr = shdr;
return 0;
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +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;
}
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);
free(b);
return -1;
}
pelf->strtabs[i] = b;
}
return 0;
}
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;
}
int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags)
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
{
struct xdr *xdr = &xdr_le;
int bit64 = 0;
struct buffer input;
Elf64_Ehdr *ehdr;
/* Zero out the parsed elf structure. */
memset(pelf, 0, sizeof(*pelf));
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
if (!iself(buffer_get(pinput))) {
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
ERROR("The stage file is not in ELF format!\n");
return -1;
}
buffer_clone(&input, pinput);
ehdr = &pelf->ehdr;
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
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);
/* Relocation processing requires section header parsing. */
if (flags & ELF_PARSE_RELOC)
flags |= ELF_PARSE_SHDR;
/* String table processing requires section header parsing. */
if (flags & ELF_PARSE_STRTAB)
flags |= ELF_PARSE_SHDR;
/* Symbole table processing requires section header parsing. */
if (flags & ELF_PARSE_SYMTAB)
flags |= ELF_PARSE_SHDR;
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;
if ((flags & ELF_PARSE_RELOC) && reloc_read(pinput, pelf, xdr, bit64))
goto fail;
if ((flags & ELF_PARSE_STRTAB) && strtab_read(pinput, pelf))
goto fail;
if ((flags & ELF_PARSE_SYMTAB) && symtab_read(pinput, pelf, xdr, bit64))
goto fail;
return 0;
fail:
parsed_elf_destroy(pelf);
return -1;
}
void parsed_elf_destroy(struct parsed_elf *pelf)
{
Elf64_Half i;
free(pelf->phdr);
free(pelf->shdr);
if (pelf->relocs != NULL) {
for (i = 0; i < pelf->ehdr.e_shnum; i++)
free(pelf->relocs[i]);
}
free(pelf->relocs);
if (pelf->strtabs != NULL) {
for (i = 0; i < pelf->ehdr.e_shnum; i++)
free(pelf->strtabs[i]);
}
free(pelf->strtabs);
free(pelf->syms);
}
/* 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));
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
if (pshdr != NULL) {
*pshdr = calloc(ehdr->e_shnum, sizeof(Elf64_Shdr));
memcpy(*pshdr, pelf.shdr, ehdr->e_shnum * sizeof(Elf64_Shdr));
}
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
parsed_elf_destroy(&pelf);
Add section header parsing and use it in the mk-payload step This completes the improvements to the ELF file parsing code. We can now parse section headers too, across all 4 combinations of word size and endianness. I had hoped to completely remove the use of htonl until I found it in cbfs_image.c. That's a battle for another day. There's now a handy macro to create magic numbers in host byte order. I'm using it for all the PAYLOAD_SEGMENT_* constants and maybe we can use it for the others too, but this is sensitive code and I'd rather change one thing at a time. To maximize the ease of use for users, elf parsing is accomplished with just one function: int elf_headers(const struct buffer *pinput, Elf64_Ehdr *ehdr, Elf64_Phdr **pphdr, Elf64_Shdr **pshdr) which requires the ehdr and pphdr pointers to be non-NULL, but allows the pshdr to be NULL. If pshdr is NULL, the code will not try to read in section headers. To satisfy our powerful scripts, I had to remove the ^M from an unrelated microcode file. BUG=None TEST=Build a peppy image (known to boot) with old and new versions and verify they are bit-for-bit the same. This was also fully tested across all chromebooks for building and booting and running chromeos. BRANCH=None Change-Id: I54dad887d922428b6175fdb6a9cdfadd8a6bb889 Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: https://chromium-review.googlesource.com/181272 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Commit-Queue: Ronald Minnich <rminnich@chromium.org> Tested-by: Ronald Minnich <rminnich@chromium.org> Signed-off-by: Ronald G. Minnich <rminnich@google.com> Reviewed-on: http://review.coreboot.org/5098 Tested-by: build bot (Jenkins) Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2013-12-30 22:16:18 +01:00
return 0;
}
/* 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) {
xdr->put64(m, shdr->sh_flags);
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 {
xdr->put32(m, shdr->sh_flags);
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;
}