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verify_pefile: relax wrapper length check

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[ Upstream commit 4fc5c74dde ]

The PE Format Specification (section "The Attribute Certificate Table
(Image Only)") states that `dwLength` is to be rounded up to 8-byte
alignment when used for traversal.  Therefore, the field is not required
to be an 8-byte multiple in the first place.

Accordingly, pesign has not performed this alignment since version
0.110.  This causes kexec failure on pesign'd binaries with "PEFILE:
Signature wrapper len wrong".  Update the comment and relax the check.

Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jarkko Sakkinen <jarkko@kernel.org>
cc: Eric Biederman <ebiederm@xmission.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: keyrings@vger.kernel.org
cc: linux-crypto@vger.kernel.org
cc: kexec@lists.infradead.org
Link: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#the-attribute-certificate-table-image-only
Link: https://github.com/rhboot/pesign
Link: https://lore.kernel.org/r/20230220171254.592347-2-rharwood@redhat.com/ # v2
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Robbie Harwood 2023-02-20 12:12:53 -05:00 committed by Greg Kroah-Hartman
parent 1773185a0a
commit fb4cb0b389
1 changed files with 8 additions and 4 deletions
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12
crypto/asymmetric_keys/verify_pefile.c
View file

@ -135,11 +135,15 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
pr_debug("sig wrapper = { %x, %x, %x }\n",
wrapper.length, wrapper.revision, wrapper.cert_type);
/* Both pesign and sbsign round up the length of certificate table
* (in optional header data directories) to 8 byte alignment.
/* sbsign rounds up the length of certificate table (in optional
* header data directories) to 8 byte alignment. However, the PE
* specification states that while entries are 8-byte aligned, this is
* not included in their length, and as a result, pesign has not
* rounded up since 0.110.
*/
if (round_up(wrapper.length, 8) != ctx->sig_len) {
pr_debug("Signature wrapper len wrong\n");
if (wrapper.length > ctx->sig_len) {
pr_debug("Signature wrapper bigger than sig len (%x > %x)\n",
ctx->sig_len, wrapper.length);
return -ELIBBAD;
}
if (wrapper.revision != WIN_CERT_REVISION_2_0) {