Implement the CodeSign EKU check to fulfill the requirements of NIAP …

…OS_PP.

Also modify the ModSign EKU check to use VerifyEKUsInPkcs7Signature() to
check the signer certificate instead of the certificate directly from the
key database.

This commit supersedes the PR#232 and PR#661 (Apply the EKU checks) so
that author's original codes can be quite independent of other modification.

To answer the question in PR#232, author also changed the conditional
statement to EFI_Status != EFI_SUCCESS right after VerifyEKUsInPkcs7Signature()
in Cryptlib/Pk/CryptPkcs7Verify.c

Signed-off-by: Dennis Tseng <[email protected]>

Cryptlib/InternalCryptLib.h

@@ -32,5 +32,37 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #define OBJ_length(o) ((o)->length)
 #endif
 
+/**
+  Check input P7Data is a wrapped ContentInfo structure or not. If not construct
+  a new structure to wrap P7Data.
+
+  Caution: This function may receive untrusted input.
+  UEFI Authenticated Variable is external input, so this function will do basic
+  check for PKCS#7 data structure.
+
+  @param[in]  P7Data       Pointer to the PKCS#7 message to verify.
+  @param[in]  P7Length     Length of the PKCS#7 message in bytes.
+  @param[out] WrapFlag     If TRUE P7Data is a ContentInfo structure, otherwise
+                           return FALSE.
+  @param[out] WrapData     If return status of this function is TRUE:
+                           1) when WrapFlag is TRUE, pointer to P7Data.
+                           2) when WrapFlag is FALSE, pointer to a new ContentInfo
+                           structure. It's caller's responsibility to free this
+                           buffer.
+  @param[out] WrapDataSize Length of ContentInfo structure in bytes.
+
+  @retval     TRUE         The operation is finished successfully.
+  @retval     FALSE        The operation is failed due to lack of resources.
+
+**/
+BOOLEAN
+WrapPkcs7Data (
+  IN  CONST UINT8  *P7Data,
+  IN  UINTN        P7Length,
+  OUT BOOLEAN      *WrapFlag,
+  OUT UINT8        **WrapData,
+  OUT UINTN        *WrapDataSize
+  );
+
 #endif
 

Cryptlib/Library/BaseCryptLib.h

@@ -2403,6 +2403,46 @@ Pkcs7Verify (
   IN  UINTN        DataLength
   );
 
+/**
+  This function receives a PKCS#7 formatted signature blob,
+  looks for the EKU SEQUENCE blob, and if found then looks
+  for all the required EKUs. This function was created so that
+  the Surface team can cut down on the number of Certificate
+  Authorities (CA's) by checking EKU's on leaf signers for
+  a specific product. This prevents one product's certificate
+  from signing another product's firmware or unlock blobs.
+
+  Note that this function does not validate the certificate chain.
+  That needs to be done before using this function.
+
+  @param[in]  Pkcs7Signature       The PKCS#7 signed information content block. An array
+                                   containing the content block with both the signature,
+                                   the signer's certificate, and any necessary intermediate
+                                   certificates.
+  @param[in]  Pkcs7SignatureSize   Number of bytes in Pkcs7Signature.
+  @param[in]  RequiredEKUs         Array of null-terminated strings listing OIDs of
+                                   required EKUs that must be present in the signature.
+  @param[in]  RequiredEKUsSize     Number of elements in the RequiredEKUs string array.
+  @param[in]  RequireAllPresent    If this is TRUE, then all of the specified EKU's
+                                   must be present in the leaf signer.  If it is
+                                   FALSE, then we will succeed if we find any
+                                   of the specified EKU's.
+
+  @retval EFI_SUCCESS              The required EKUs were found in the signature.
+  @retval EFI_INVALID_PARAMETER    A parameter was invalid.
+  @retval EFI_NOT_FOUND            One or more EKU's were not found in the signature.
+
+**/
+EFI_STATUS
+EFIAPI
+VerifyEKUsInPkcs7Signature (
+  IN CONST UINT8    *Pkcs7Signature,
+  IN CONST UINT32   SignatureSize,
+  IN CONST CHAR8    *RequiredEKUs[],
+  IN CONST UINT32   RequiredEKUsSize,
+  IN BOOLEAN        RequireAllPresent
+  );
+
 /**
   Extracts the attached content from a PKCS#7 signed data if existed. The input signed
   data could be wrapped in a ContentInfo structure.

Cryptlib/Makefile

@@ -57,6 +57,7 @@ OBJS		=   Hash/CryptMd4Null.o \
 		    Pk/CryptRsaExtNull.o \
 		    Pk/CryptPkcs7SignNull.o \
 		    Pk/CryptPkcs7Verify.o \
+		    Pk/CryptPkcs7VerifyEku.o \
 		    Pk/CryptDhNull.o \
 		    Pk/CryptTs.o \
 		    Pk/CryptX509.o \

Cryptlib/Pk/CryptPkcs7Verify.c

@@ -29,6 +29,8 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #include <openssl/pkcs7.h>
 
 UINT8 mOidValue[9] = { 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x07, 0x02 };
+/* EKU CodeSign */
+CHAR8 mOidCodeSign[] = "1.3.6.1.5.5.7.3.3";
 
 #if 1
 #if OPENSSL_VERSION_NUMBER < 0x10100000L
@@ -846,6 +848,8 @@ Pkcs7Verify (
   CONST UINT8 *Temp;
   UINTN       SignedDataSize;
   BOOLEAN     Wrapped;
+  CONST CHAR8 *Ekus[1];
+  EFI_STATUS  EFI_Status;
 
   //
   // Check input parameters.
@@ -859,6 +863,7 @@ Pkcs7Verify (
   DataBio   = NULL;
   Cert      = NULL;
   CertStore = NULL;
+  Ekus[0]   = mOidCodeSign;
 
   //
   // Register & Initialize necessary digest algorithms for PKCS#7 Handling
@@ -958,6 +963,11 @@ Pkcs7Verify (
   //
   X509_STORE_set_purpose (CertStore, X509_PURPOSE_ANY);
 
+  EFI_Status = VerifyEKUsInPkcs7Signature(P7Data, P7Length, Ekus, 1, TRUE);
+  if (EFI_Status != EFI_SUCCESS) {
+	  goto _Exit;
+  }
+
   //
   // Verifies the PKCS#7 signedData structure
   //