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Implement checksum verification for gunzip

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This implements the crc32 check for the gzip format. Support for zlib's
adler checksum is not included, yet.
This commit is contained in:
Stefan Fritsch 2016-05-01 14:32:30 +02:00 committed by Vladimir Serbinenko
parent c42acc23ff
commit b18ce97c67
1 changed files with 41 additions and 5 deletions
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46
grub-core/io/gzio.c
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@ -43,6 +43,7 @@
#include <grub/dl.h>
#include <grub/deflate.h>
#include <grub/i18n.h>
#include <grub/crypto.h>
GRUB_MOD_LICENSE ("GPLv3+");
@ -94,6 +95,14 @@ struct grub_gzio
struct huft *tl;
/* The distance code table. */
struct huft *td;
/* The checksum algorithm */
const gcry_md_spec_t *hdesc;
/* The wanted checksum */
grub_uint32_t orig_checksum;
/* The uncompressed length */
grub_size_t orig_len;
/* Context for checksum calculation */
grub_uint8_t *hcontext;
/* The lookup bits for the literal/length code table. */
int bl;
/* The lookup bits for the distance code table. */
@ -180,7 +189,7 @@ test_gzip_header (grub_file_t file)
grub_uint8_t os_type;
} hdr;
grub_uint16_t extra_len;
grub_uint32_t orig_len;
grub_uint32_t crc32;
grub_gzio_t gzio = file->data;
if (grub_file_tell (gzio->file) != 0)
@ -215,12 +224,15 @@ test_gzip_header (grub_file_t file)
/* FIXME: don't do this on not easily seekable files. */
{
grub_file_seek (gzio->file, grub_file_size (gzio->file) - 4);
if (grub_file_read (gzio->file, &orig_len, 4) != 4)
grub_file_seek (gzio->file, grub_file_size (gzio->file) - 8);
if (grub_file_read (gzio->file, &crc32, 4) != 4)
return 0;
gzio->orig_checksum = grub_le_to_cpu32 (crc32);
if (grub_file_read (gzio->file, &gzio->orig_len, 4) != 4)
return 0;
/* FIXME: this does not handle files whose original size is over 4GB.
But how can we know the real original size? */
file->size = grub_le_to_cpu32 (orig_len);
file->size = grub_le_to_cpu32 (gzio->orig_len);
}
initialize_tables (gzio);
@ -1095,7 +1107,23 @@ inflate_window (grub_gzio_t gzio)
gzio->saved_offset += gzio->wp;
/* XXX do CRC calculation here! */
if (gzio->hcontext)
{
gzio->hdesc->write (gzio->hcontext, gzio->slide, gzio->wp);
if (gzio->saved_offset == gzio->orig_len)
{
grub_uint32_t csum;
gzio->hdesc->final (gzio->hcontext);
csum = *(grub_uint32_t *)gzio->hdesc->read (gzio->hcontext);
csum = grub_be_to_cpu32 (csum);
if (csum != gzio->orig_checksum)
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
"checksum mismatch %08x/%08x",
gzio->orig_checksum, csum);
}
}
}
@ -1118,6 +1146,9 @@ initialize_tables (grub_gzio_t gzio)
huft_free (gzio->td);
gzio->tl = NULL;
gzio->td = NULL;
if (gzio->hcontext)
gzio->hdesc->init(gzio->hcontext);
}
@ -1143,6 +1174,9 @@ grub_gzio_open (grub_file_t io, const char *name __attribute__ ((unused)))
gzio->file = io;
gzio->hdesc = GRUB_MD_CRC32;
gzio->hcontext = grub_malloc(gzio->hdesc->contextsize);
file->device = io->device;
file->data = gzio;
file->fs = &grub_gzio_fs;
@ -1151,6 +1185,7 @@ grub_gzio_open (grub_file_t io, const char *name __attribute__ ((unused)))
if (! test_gzip_header (file))
{
grub_errno = GRUB_ERR_NONE;
grub_free (gzio->hcontext);
grub_free (gzio);
grub_free (file);
grub_file_seek (io, 0);
@ -1287,6 +1322,7 @@ grub_gzio_close (grub_file_t file)
grub_file_close (gzio->file);
huft_free (gzio->tl);
huft_free (gzio->td);
grub_free (gzio->hcontext);
grub_free (gzio);
/* No need to close the same device twice. */