diff options
Diffstat (limited to 'FmpDevicePkg/FmpDxe/DetectTestKey.c')
| -rw-r--r-- | FmpDevicePkg/FmpDxe/DetectTestKey.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/FmpDevicePkg/FmpDxe/DetectTestKey.c b/FmpDevicePkg/FmpDxe/DetectTestKey.c new file mode 100644 index 0000000000..0a6e37eded --- /dev/null +++ b/FmpDevicePkg/FmpDxe/DetectTestKey.c @@ -0,0 +1,166 @@ +/** @file
+ Detects if PcdFmpDevicePkcs7CertBufferXdr contains a test key.
+
+ Copyright (c) 2018, Intel Corporation. All rights reserved.<BR>
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+ 1. Redistributions of source code must retain the above copyright notice,
+ this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+**/
+
+#include <PiDxe.h>
+#include <Library/DebugLib.h>
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/PcdLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/BaseCryptLib.h>
+
+/**
+ Check to see if any of the keys in PcdFmpDevicePkcs7CertBufferXdr matches
+ the test key. PcdFmpDeviceTestKeySha256Digest contains the SHA256 hash of
+ the test key. For each key in PcdFmpDevicePkcs7CertBufferXdr, compute the
+ SHA256 hash and compare it to PcdFmpDeviceTestKeySha256Digest. If the
+ SHA256 hash matches or there is then error computing the SHA256 hash, then
+ set PcdTestKeyUsed to TRUE. Skip this check if PcdTestKeyUsed is already
+ TRUE or PcdFmpDeviceTestKeySha256Digest is not exactly SHA256_DIGEST_SIZE
+ bytes.
+**/
+VOID
+DetectTestKey (
+ VOID
+ )
+{
+ BOOLEAN TestKeyUsed;
+ UINTN PublicKeyDataLength;
+ UINT8 *PublicKeyDataXdr;
+ UINT8 *PublicKeyDataXdrEnd;
+ VOID *HashContext;
+ UINT8 Digest[SHA256_DIGEST_SIZE];
+
+ //
+ // If PcdFmpDeviceTestKeySha256Digest is not exacty SHA256_DIGEST_SIZE bytes,
+ // then skip the test key detection.
+ //
+ if (PcdGetSize (PcdFmpDeviceTestKeySha256Digest) != SHA256_DIGEST_SIZE) {
+ return;
+ }
+
+ //
+ // If PcdTestKeyUsed is already TRUE, then skip test key detection
+ //
+ TestKeyUsed = PcdGetBool (PcdTestKeyUsed);
+ if (TestKeyUsed) {
+ return;
+ }
+
+ //
+ // If PcdFmpDevicePkcs7CertBufferXdr is invalid, then skip test key detection
+ //
+ PublicKeyDataXdr = PcdGetPtr (PcdFmpDevicePkcs7CertBufferXdr);
+ PublicKeyDataXdrEnd = PublicKeyDataXdr + PcdGetSize (PcdFmpDevicePkcs7CertBufferXdr);
+ if (PublicKeyDataXdr == NULL || PublicKeyDataXdr == PublicKeyDataXdrEnd) {
+ return;
+ }
+
+ //
+ // Allocate hash context buffer required for SHA 256
+ //
+ HashContext = AllocatePool (Sha256GetContextSize ());
+ if (HashContext == NULL) {
+ TestKeyUsed = TRUE;
+ }
+
+ //
+ // Loop through all keys in PcdFmpDevicePkcs7CertBufferXdr
+ //
+ while (!TestKeyUsed && PublicKeyDataXdr < PublicKeyDataXdrEnd) {
+ if (PublicKeyDataXdr + sizeof (UINT32) > PublicKeyDataXdrEnd) {
+ //
+ // Key data extends beyond end of PCD
+ //
+ break;
+ }
+ //
+ // Read key length stored in big endian format
+ //
+ PublicKeyDataLength = SwapBytes32 (*(UINT32 *)(PublicKeyDataXdr));
+ //
+ // Point to the start of the key data
+ //
+ PublicKeyDataXdr += sizeof (UINT32);
+ if (PublicKeyDataXdr + PublicKeyDataLength > PublicKeyDataXdrEnd) {
+ //
+ // Key data extends beyond end of PCD
+ //
+ break;
+ }
+
+ //
+ // Hash public key from PcdFmpDevicePkcs7CertBufferXdr using SHA256.
+ // If error occurs computing SHA256, then assume test key is in use.
+ //
+ ZeroMem (Digest, SHA256_DIGEST_SIZE);
+ if (!Sha256Init (HashContext)) {
+ TestKeyUsed = TRUE;
+ break;
+ }
+ if (!Sha256Update (HashContext, PublicKeyDataXdr, PublicKeyDataLength)) {
+ TestKeyUsed = TRUE;
+ break;
+ }
+ if (!Sha256Final (HashContext, Digest)) {
+ TestKeyUsed = TRUE;
+ break;
+ }
+
+ //
+ // Check if SHA256 hash of public key matches SHA256 hash of test key
+ //
+ if (CompareMem (Digest, PcdGetPtr (PcdFmpDeviceTestKeySha256Digest), SHA256_DIGEST_SIZE) == 0) {
+ TestKeyUsed = TRUE;
+ break;
+ }
+
+ //
+ // Point to start of next key
+ //
+ PublicKeyDataXdr += PublicKeyDataLength;
+ PublicKeyDataXdr = (UINT8 *)ALIGN_POINTER (PublicKeyDataXdr, sizeof (UINT32));
+ }
+
+ //
+ // Free hash context buffer required for SHA 256
+ //
+ if (HashContext != NULL) {
+ FreePool (HashContext);
+ HashContext = NULL;
+ }
+
+ //
+ // If test key detected or an error occured checking for the test key, then
+ // set PcdTestKeyUsed to TRUE.
+ //
+ if (TestKeyUsed) {
+ DEBUG ((DEBUG_INFO, "FmpDxe: Test key detected in PcdFmpDevicePkcs7CertBufferXdr.\n"));
+ PcdSetBoolS (PcdTestKeyUsed, TRUE);
+ } else {
+ DEBUG ((DEBUG_INFO, "FmpDxe: No test key detected in PcdFmpDevicePkcs7CertBufferXdr.\n"));
+ }
+}
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