Fix KeyBlockVerify() to take an explicit param for whether to use hash only.

firmware/lib/vboot_common.c

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Common functions between firmware and kernel verified boot.
  * (Firmware portion)
  */
 
 
 #include "vboot_common.h"
@@ skipping 38 matching lines @@
  * the parent data.  Returns 0 if inside, 1 if error. */
 int VerifyMemberInside(const void* parent, uint64_t parent_size,
                        const void* member, uint64_t member_size,
                        uint64_t member_data_offset,
                        uint64_t member_data_size) {
   uint64_t end = OffsetOf(parent, member);
 
   if (end > parent_size)
     return 1;
 
+  if (UINT64_MAX - end < member_size)
+    return 1;  /* Detect wraparound in integer math */
   if (end + member_size > parent_size)
     return 1;
 
+  if (UINT64_MAX - end < member_data_offset)
+    return 1;
   end += member_data_offset;
   if (end > parent_size)
     return 1;
+
+  if (UINT64_MAX - end < member_data_size)
+    return 1;
   if (end + member_data_size > parent_size)
     return 1;
 
   return 0;
 }
 
 
 int VerifyPublicKeyInside(const void* parent, uint64_t parent_size,
                           const VbPublicKey* key) {
   return VerifyMemberInside(parent, parent_size,
@@ skipping 81 matching lines @@
 
   if (!RSAVerifyBinaryWithDigest_f(NULL, key, digest,
                          GetSignatureDataC(sig), key->algorithm))
     return 1;
 
   return 0;
 }
 
 
 int KeyBlockVerify(const VbKeyBlockHeader* block, uint64_t size,
-                   const VbPublicKey *key) {
+                   const VbPublicKey *key, int hash_only) {
 
   const VbSignature* sig;
 
   /* Sanity checks before attempting signature of data */
   if (SafeMemcmp(block->magic, KEY_BLOCK_MAGIC, KEY_BLOCK_MAGIC_SIZE)) {
     VBDEBUG(("Not a valid verified boot key block.\n"));
     return VBOOT_KEY_BLOCK_INVALID;
   }
   if (block->header_version_major != KEY_BLOCK_HEADER_VERSION_MAJOR) {
     VBDEBUG(("Incompatible key block header version.\n"));
     return VBOOT_KEY_BLOCK_INVALID;
   }
   if (size < block->key_block_size) {
     VBDEBUG(("Not enough data for key block.\n"));
     return VBOOT_KEY_BLOCK_INVALID;
   }
+  if (!hash_only && !key) {
+    VBDEBUG(("Missing required public key.\n"));
+    return VBOOT_PUBLIC_KEY_INVALID;
+  }
 
   /* Check signature or hash, depending on whether we provide a key. Note that

[gauravsh, 2010/08/17 22:24:13]

update comment to reflect the hash_only flag

[Randall Spangler, 2010/08/17 22:43:55]

Done.

    * we don't require a key even if the keyblock has a signature, because the
    * caller may not care if the keyblock itself is signed (for example, booting
    * a Google-signed kernel in developer mode).
    */
-  if (key) {
+  if (hash_only) {
+    /* Check hash */
+    uint8_t* header_checksum = NULL;
+    int rv;
+
+    sig = &block->key_block_checksum;
+
+    if (VerifySignatureInside(block, block->key_block_size, sig)) {
+      VBDEBUG(("Key block hash off end of block\n"));
+      return VBOOT_KEY_BLOCK_INVALID;
+    }
+    if (sig->sig_size != SHA512_DIGEST_SIZE) {
+      VBDEBUG(("Wrong hash size for key block.\n"));
+      return VBOOT_KEY_BLOCK_INVALID;
+    }
+
+    VBDEBUG(("Checking key block hash only...\n"));
+    header_checksum = DigestBuf((const uint8_t*)block, sig->data_size,
+                                SHA512_DIGEST_ALGORITHM);
+    rv = SafeMemcmp(header_checksum, GetSignatureDataC(sig),
+                    SHA512_DIGEST_SIZE);
+    Free(header_checksum);
+    if (rv) {
+      VBDEBUG(("Invalid key block hash.\n"));
+      return VBOOT_KEY_BLOCK_HASH;
+    }
+  } else {
     /* Check signature */
     RSAPublicKey* rsa;
     int rv;
 
     sig = &block->key_block_signature;
 
     if (VerifySignatureInside(block, block->key_block_size, sig)) {
       VBDEBUG(("Key block signature off end of block\n"));
       return VBOOT_KEY_BLOCK_INVALID;
     }
 
     rsa = PublicKeyToRSA(key);
     if (!rsa) {
       VBDEBUG(("Invalid public key\n"));
       return VBOOT_PUBLIC_KEY_INVALID;
     }
 
     /* Make sure advertised signature data sizes are sane. */
     if (block->key_block_size < sig->data_size) {
       VBDEBUG(("Signature calculated past end of the block\n"));
       return VBOOT_KEY_BLOCK_INVALID;
     }
     VBDEBUG(("Checking key block signature...\n"));
     rv = VerifyData((const uint8_t*)block, size, sig, rsa);
     RSAPublicKeyFree(rsa);
     if (rv) {
       VBDEBUG(("Invalid key block signature.\n"));
       return VBOOT_KEY_BLOCK_SIGNATURE;
     }
-  } else {
-    /* Check hash */
-    uint8_t* header_checksum = NULL;
-    int rv;
-
-    sig = &block->key_block_checksum;
-
-    if (VerifySignatureInside(block, block->key_block_size, sig)) {
-      VBDEBUG(("Key block hash off end of block\n"));
-      return VBOOT_KEY_BLOCK_INVALID;
-    }
-    if (sig->sig_size != SHA512_DIGEST_SIZE) {
-      VBDEBUG(("Wrong hash size for key block.\n"));
-      return VBOOT_KEY_BLOCK_INVALID;
-    }
-
-    VBDEBUG(("Checking key block hash only...\n"));
-    header_checksum = DigestBuf((const uint8_t*)block, sig->data_size,
-                                SHA512_DIGEST_ALGORITHM);
-    rv = SafeMemcmp(header_checksum, GetSignatureDataC(sig),
-                    SHA512_DIGEST_SIZE);
-    Free(header_checksum);
-    if (rv) {
-      VBDEBUG(("Invalid key block hash.\n"));
-      return VBOOT_KEY_BLOCK_HASH;
-    }
   }
 
   /* Verify we signed enough data */
   if (sig->data_size < sizeof(VbKeyBlockHeader)) {
     VBDEBUG(("Didn't sign enough data\n"));
     return VBOOT_KEY_BLOCK_INVALID;
   }
 
   /* Verify data key is inside the block and inside signed data */
   if (VerifyPublicKeyInside(block, block->key_block_size, &block->data_key)) {
@@ skipping 102 matching lines @@
   /* Verify body signature is inside the block */
   if (VerifySignatureInside(preamble, preamble->preamble_size,
                             &preamble->body_signature)) {
     VBDEBUG(("Kernel body signature off end of preamble\n"));
     return VBOOT_PREAMBLE_INVALID;
   }
 
   /* Success */
   return VBOOT_SUCCESS;
 }