REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4305
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....@intel.com> Cc: Jian J Wang <jian.j.w...@intel.com> Cc: Min Xu <min.m...@intel.com> Signed-off-by: Jan Bobek <jbo...@nvidia.com> --- .../Library/AuthVariableLib/AuthService.c | 50 ++++++++++++++++--- 1 file changed, 42 insertions(+), 8 deletions(-) diff --git a/SecurityPkg/Library/AuthVariableLib/AuthService.c b/SecurityPkg/Library/AuthVariableLib/AuthService.c index 054ee4d1d988..9beeca09aeba 100644 --- a/SecurityPkg/Library/AuthVariableLib/AuthService.c +++ b/SecurityPkg/Library/AuthVariableLib/AuthService.c @@ -1925,7 +1925,7 @@ VerifyTimeBasedPayload ( // SignedData.digestAlgorithms shall contain the digest algorithm used when preparing the // signature. Only a digest algorithm of SHA-256 is accepted. // - // According to PKCS#7 Definition: + // According to PKCS#7 Definition (https://www.rfc-editor.org/rfc/rfc2315): // SignedData ::= SEQUENCE { // version Version, // digestAlgorithms DigestAlgorithmIdentifiers, @@ -1933,15 +1933,49 @@ 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. + // + // Both condition can be handled in WrapPkcs7Data() in CryptPkcs7VerifyCommon.c. + // + // See below examples: + // + // 1. Without ContentInfo + // 30 82 0c da // SEQUENCE (5 element) (3294 BYTES) -- SignedData + // 02 01 01 // INTEGER 1 -- Version + // 31 0f // SET (1 element) (15 BYTES) -- DigestAlgorithmIdentifiers + // 30 0d // SEQUENCE (2 element) (13 BYTES) -- AlgorithmIdentifier + // 06 09 // OBJECT-IDENTIFIER (9 BYTES) -- algorithm + // 60 86 48 01 65 03 04 02 01 // sha256 [2.16.840.1.101.3.4.2.1] + // 05 00 // NULL (0 BYTES) -- parameters + // + // Example from: https://uefi.org/revocationlistfile + // + // 2. With ContentInfo + // 30 82 05 90 // SEQUENCE (1424 BYTES) -- ContentInfo + // 06 09 // OBJECT-IDENTIFIER (9 BYTES) -- ContentType + // 2a 86 48 86 f7 0d 01 07 02 // signedData [1.2.840.113549.1.7.2] + // a0 82 05 81 // CONTEXT-SPECIFIC CONSTRUCTED TAG 0 (1409 BYTES) -- content + // 30 82 05 7d // SEQUENCE (1405 BYTES) -- SignedData + // 02 01 01 // INTEGER 1 -- Version + // 31 0f // SET (1 element) (15 BYTES) -- DigestAlgorithmIdentifiers + // 30 0d // SEQUENCE (13 BYTES) -- AlgorithmIdentifier + // 06 09 // OBJECT-IDENTIFIER (9 BYTES) -- algorithm + // 60 86 48 01 65 03 04 02 01 // sha256 [2.16.840.1.101.3.4.2.1] + // 05 00 // NULL (0 BYTES) -- parameters + // + // Example generated with: https://wiki.archlinux.org/title/Unified_Extensible_Firmware_Interface/Secure_Boot#Manual_process // 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; } } -- 2.30.2 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#98951): https://edk2.groups.io/g/devel/message/98951 Mute This Topic: https://groups.io/mt/96462302/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
