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