image: Allow manipulation of i386 PE/COFF files
Replace struct image->aouthdr with a union of the 32- and 64-bit a.out
header definitions, and abstract the relevant parsing code into the
image_pecoff_parse_{32,64} functions.
We also move all references of data in the a.out header to these
functions, so we don't need to lookup the machine types elsewhere.
Based on a patch by Maxim Kammerer <mk@dee.su>.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
This commit is contained in:
Jeremy Kerr
parent
e027b87cff
commit
e1b58d6ccb
2 changed files with 89 additions and 23 deletions
100
image.c
100
image.c
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@ -77,13 +77,65 @@ static uint16_t __pehdr_u16(char field[])
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#define pehdr_u32(f) __pehdr_u32(f + BUILD_ASSERT_OR_ZERO(sizeof(f) == 4))
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#define pehdr_u16(f) __pehdr_u16(f + BUILD_ASSERT_OR_ZERO(sizeof(f) == 2))
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/* Machine-specific PE/COFF parse functions. These parse the relevant a.out
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* header for the machine type, and set the following members of struct image:
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* - aouthdr_size
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* - file_alignment
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* - header_size
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* - data_dir
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* - checksum
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*
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* These functions require image->aouthdr to be set by the caller.
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*/
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static int image_pecoff_parse_32(struct image *image)
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{
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if (image->aouthdr.aout_32->standard.magic[0] != 0x0b ||
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image->aouthdr.aout_32->standard.magic[1] != 0x01) {
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fprintf(stderr, "Invalid a.out machine type\n");
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return -1;
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}
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image->aouthdr_size = sizeof(*image->aouthdr.aout_32);
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image->file_alignment =
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pehdr_u32(image->aouthdr.aout_32->FileAlignment);
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image->header_size =
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pehdr_u32(image->aouthdr.aout_32->SizeOfHeaders);
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image->data_dir = (void *)image->aouthdr.aout_32->DataDirectory;
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image->checksum = (uint32_t *)image->aouthdr.aout_32->CheckSum;
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return 0;
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}
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static int image_pecoff_parse_64(struct image *image)
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{
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if (image->aouthdr.aout_64->standard.magic[0] != 0x0b ||
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image->aouthdr.aout_64->standard.magic[1] != 0x02) {
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fprintf(stderr, "Invalid a.out machine type\n");
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return -1;
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}
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image->aouthdr_size = sizeof(*image->aouthdr.aout_64);
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image->file_alignment =
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pehdr_u32(image->aouthdr.aout_64->FileAlignment);
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image->header_size =
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pehdr_u32(image->aouthdr.aout_64->SizeOfHeaders);
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image->data_dir = (void *)image->aouthdr.aout_64->DataDirectory;
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image->checksum = (uint32_t *)image->aouthdr.aout_64->CheckSum;
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return 0;
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}
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static int image_pecoff_parse(struct image *image)
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{
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struct cert_table_header *cert_table;
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char nt_sig[] = {'P', 'E', 0, 0};
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size_t size = image->size;
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void *buf = image->buf;
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uint16_t magic;
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uint32_t addr;
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int rc;
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/* sanity checks */
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if (size < sizeof(*image->doshdr)) {
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@ -117,35 +169,40 @@ static int image_pecoff_parse(struct image *image)
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return -1;
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}
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if (pehdr_u16(image->pehdr->f_magic) != IMAGE_FILE_MACHINE_AMD64) {
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fprintf(stderr, "Invalid PE header magic for x86_64\n");
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/* a.out header directly follows PE header */
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image->aouthdr.addr = image->pehdr + 1;
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magic = pehdr_u16(image->pehdr->f_magic);
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if (magic == IMAGE_FILE_MACHINE_AMD64) {
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rc = image_pecoff_parse_64(image);
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} else if (magic == IMAGE_FILE_MACHINE_I386) {
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rc = image_pecoff_parse_32(image);
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} else {
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fprintf(stderr, "Invalid PE header magic\n");
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return -1;
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}
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if (pehdr_u16(image->pehdr->f_opthdr) != sizeof(*image->aouthdr)) {
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if (rc) {
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fprintf(stderr, "Error parsing a.out header\n");
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return -1;
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}
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/* we have the data_dir now, from parsing the a.out header */
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image->data_dir_sigtable = &image->data_dir[DATA_DIR_CERT_TABLE];
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if (pehdr_u16(image->pehdr->f_opthdr) != image->aouthdr_size) {
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fprintf(stderr, "Invalid a.out header size\n");
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return -1;
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}
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if (image->size < sizeof(*image->doshdr) + sizeof(*image->pehdr)
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+ sizeof(*image->aouthdr)) {
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+ image->aouthdr_size) {
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fprintf(stderr, "file is too small for a.out header\n");
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return -1;
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}
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/* a.out header directly follows PE header */
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image->aouthdr = (void *)(image->pehdr+1);
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if (image->aouthdr->standard.magic[0] != 0x0b ||
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image->aouthdr->standard.magic[1] != 0x02) {
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fprintf(stderr, "Invalid a.out machine type\n");
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return -1;
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}
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image->data_dir = (void *)image->aouthdr->DataDirectory;
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image->data_dir_sigtable = &image->data_dir[DATA_DIR_CERT_TABLE];
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image->checksum = (uint32_t *)image->aouthdr->CheckSum;
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image->cert_table_size = image->data_dir_sigtable->size;
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if (image->cert_table_size)
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cert_table = buf + image->data_dir_sigtable->addr;
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@ -165,7 +222,7 @@ static int image_pecoff_parse(struct image *image)
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}
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image->sections = pehdr_u16(image->pehdr->f_nscns);
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image->scnhdr = (void *)(image->aouthdr+1);
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image->scnhdr = image->aouthdr.addr + image->aouthdr_size;
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return 0;
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}
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@ -222,11 +279,9 @@ int image_find_regions(struct image *image)
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struct region *regions;
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void *buf = image->buf;
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int i, gap_warn;
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uint32_t align;
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size_t bytes;
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gap_warn = 0;
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align = pehdr_u32(image->aouthdr->FileAlignment);
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/* now we know where the checksum and cert table data is, we can
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* construct regions that need to be signed */
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@ -260,7 +315,7 @@ int image_find_regions(struct image *image)
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set_region_from_range(®ions[2],
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(void *)image->data_dir_sigtable
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+ sizeof(struct data_dir_entry),
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buf + pehdr_u32(image->aouthdr->SizeOfHeaders));
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buf + image->header_size);
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regions[2].name = "datadir[CERT]->headers";
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bytes += regions[2].size;
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@ -282,7 +337,8 @@ int image_find_regions(struct image *image)
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regions = image->checksum_regions;
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regions[i + 3].data = buf + file_offset;
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regions[i + 3].size = align_up(file_size, align);
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regions[i + 3].size = align_up(file_size,
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image->file_alignment);
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regions[i + 3].name = talloc_strndup(image->checksum_regions,
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image->scnhdr[i].s_name, 8);
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bytes += regions[i + 3].size;
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12
image.h
12
image.h
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@ -54,7 +54,12 @@ struct image {
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uint32_t *checksum;
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struct external_PEI_DOS_hdr *doshdr;
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struct external_PEI_IMAGE_hdr *pehdr;
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PEPAOUTHDR *aouthdr;
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union {
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PEPAOUTHDR *aout_64;
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PEAOUTHDR *aout_32;
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void *addr;
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} aouthdr;
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unsigned int aouthdr_size;
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struct data_dir_entry *data_dir;
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struct data_dir_entry *data_dir_sigtable;
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struct external_scnhdr *scnhdr;
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@ -63,6 +68,11 @@ struct image {
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void *cert_table;
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int cert_table_size;
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/* We cache a few values from the aout header, so we don't have to
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* keep checking whether to use the 32- or 64-bit version */
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uint32_t file_alignment;
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uint32_t header_size;
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/* Regions that are included in the image hash: populated
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* during image parsing, then used during the hash process.
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*/
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