[edk2-devel] [PATCH 1/1] SecurityPkg/AuthVariableLib: Check SHA-256 OID with ContentInfo present
Jan Bobek via groups.io
jbobek=nvidia.com at groups.io
Tue Jan 3 22:29:47 UTC 2023
Anothing ping. Comments/reviews/merge highly appreciated.
Thank you,
-Jan
Jan Bobek writes:
> Ping. Can I get a review and/or some comments on this patch, please?
>
> Thanks,
> -Jan
>
> Jan Bobek writes:
>
>> Based on whether the DER-encoded ContentInfo structure is present in
>> authenticated SetVariable payload or not, the SHA-256 OID can be
>> located at different places.
>>
>> UEFI specification explicitly states the driver shall support both
>> cases, but the old code assumed ContentInfo was not present and
>> incorrectly rejected authenticated variable updates when it were
>> present.
>>
>> Cc: Jiewen Yao <jiewen.yao at intel.com>
>> Cc: Jian J Wang <jian.j.wang at intel.com>
>> Cc: Min Xu <min.m.xu at intel.com>
>> Signed-off-by: Jan Bobek <jbobek at nvidia.com>
>> ---
>> .../Library/AuthVariableLib/AuthService.c | 18 +++++++++++-------
>> 1 file changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/SecurityPkg/Library/AuthVariableLib/AuthService.c b/SecurityPkg/Library/AuthVariableLib/AuthService.c
>> index 054ee4d1d988..de8baccab410 100644
>> --- a/SecurityPkg/Library/AuthVariableLib/AuthService.c
>> +++ b/SecurityPkg/Library/AuthVariableLib/AuthService.c
>> @@ -1933,15 +1933,19 @@ VerifyTimeBasedPayload (
>> // .... }
>> // The DigestAlgorithmIdentifiers can be used to determine the hash algorithm
>> // in VARIABLE_AUTHENTICATION_2 descriptor.
>> - // This field has the fixed offset (+13) and be calculated based on two bytes of length encoding.
>> + // This field has the fixed offset (+13) or (+32) based on whether the DER-encoded
>> + // ContentInfo structure is present or not, and can be calculated based on two
>> + // bytes of length encoding.
>> //
>> if ((Attributes & EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) != 0) {
>> - if (SigDataSize >= (13 + sizeof (mSha256OidValue))) {
>> - if (((*(SigData + 1) & TWO_BYTE_ENCODE) != TWO_BYTE_ENCODE) ||
>> - (CompareMem (SigData + 13, &mSha256OidValue, sizeof (mSha256OidValue)) != 0))
>> - {
>> - return EFI_SECURITY_VIOLATION;
>> - }
>> + if ( ( (SigDataSize >= (13 + sizeof (mSha256OidValue)))
>> + && ( ((*(SigData + 1) & TWO_BYTE_ENCODE) != TWO_BYTE_ENCODE)
>> + || (CompareMem (SigData + 13, &mSha256OidValue, sizeof (mSha256OidValue)) != 0)))
>> + && ( (SigDataSize >= (32 + sizeof (mSha256OidValue)))
>> + && ( ((*(SigData + 20) & TWO_BYTE_ENCODE) != TWO_BYTE_ENCODE)
>> + || (CompareMem (SigData + 32, &mSha256OidValue, sizeof (mSha256OidValue)) != 0))))
>> + {
>> + return EFI_SECURITY_VIOLATION;
>> }
>> }
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