1 files changed, 351 insertions, 0 deletions
diff --git a/security/certverifier/OCSPCache.cpp b/security/certverifier/OCSPCache.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This code is made available to you under your choice of the following sets
+ * of licensing terms:
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+/* Copyright 2013 Mozilla Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "OCSPCache.h"
+
+#include <limits>
+
+#include "NSSCertDBTrustDomain.h"
+#include "pk11pub.h"
+#include "mozilla/StaticPrefs_privacy.h"
+#include "mozpkix/pkixnss.h"
+#include "ScopedNSSTypes.h"
+#include "secerr.h"
+
+extern mozilla::LazyLogModule gCertVerifierLog;
+
+using namespace mozilla::pkix;
+
+namespace mozilla {
+namespace psm {
+
+typedef mozilla::pkix::Result Result;
+
+static SECStatus DigestLength(UniquePK11Context& context, uint32_t length) {
+  // Restrict length to 2 bytes because it should be big enough for all
+  // inputs this code will actually see and that it is well-defined and
+  // type-size-independent.
+  if (length >= 65536) {
+    return SECFailure;
+  }
+  unsigned char array[2];
+  array[0] = length & 255;
+  array[1] = (length >> 8) & 255;
+
+  return PK11_DigestOp(context.get(), array, MOZ_ARRAY_LENGTH(array));
+}
+
+// Let derIssuer be the DER encoding of the issuer of certID.
+// Let derPublicKey be the DER encoding of the public key of certID.
+// Let serialNumber be the bytes of the serial number of certID.
+// Let serialNumberLen be the number of bytes of serialNumber.
+// Let firstPartyDomain be the first party domain of originAttributes.
+// It is only non-empty when "privacy.firstParty.isolate" is enabled, in order
+// to isolate OCSP cache by first party.
+// Let firstPartyDomainLen be the number of bytes of firstPartyDomain.
+// Let partitionKey be the partition key of originAttributes.
+// Let partitionKeyLen be the number of bytes of partitionKey.
+// The value calculated is SHA384(derIssuer || derPublicKey || serialNumberLen
+// || serialNumber || firstPartyDomainLen || firstPartyDomain || partitionKeyLen
+// || partitionKey).
+// Because the DER encodings include the length of the data encoded, and we also
+// include the length of serialNumber and originAttributes, there do not exist
+// A(derIssuerA, derPublicKeyA, serialNumberLenA, serialNumberA,
+// originAttributesLenA, originAttributesA) and B(derIssuerB, derPublicKeyB,
+// serialNumberLenB, serialNumberB, originAttributesLenB, originAttributesB)
+// such that the concatenation of each tuple results in the same string of
+// bytes but where each part in A is not equal to its counterpart in B. This is
+// important because as a result it is computationally infeasible to find
+// collisions that would subvert this cache (given that SHA384 is a
+// cryptographically-secure hash function).
+static SECStatus CertIDHash(SHA384Buffer& buf, const CertID& certID,
+                            const OriginAttributes& originAttributes) {
+  UniquePK11Context context(PK11_CreateDigestContext(SEC_OID_SHA384));
+  if (!context) {
+    return SECFailure;
+  }
+  SECStatus rv = PK11_DigestBegin(context.get());
+  if (rv != SECSuccess) {
+    return rv;
+  }
+  SECItem certIDIssuer = UnsafeMapInputToSECItem(certID.issuer);
+  rv = PK11_DigestOp(context.get(), certIDIssuer.data, certIDIssuer.len);
+  if (rv != SECSuccess) {
+    return rv;
+  }
+  SECItem certIDIssuerSubjectPublicKeyInfo =
+      UnsafeMapInputToSECItem(certID.issuerSubjectPublicKeyInfo);
+  rv = PK11_DigestOp(context.get(), certIDIssuerSubjectPublicKeyInfo.data,
+                     certIDIssuerSubjectPublicKeyInfo.len);
+  if (rv != SECSuccess) {
+    return rv;
+  }
+  SECItem certIDSerialNumber = UnsafeMapInputToSECItem(certID.serialNumber);
+  rv = DigestLength(context, certIDSerialNumber.len);
+  if (rv != SECSuccess) {
+    return rv;
+  }
+  rv = PK11_DigestOp(context.get(), certIDSerialNumber.data,
+                     certIDSerialNumber.len);
+  if (rv != SECSuccess) {
+    return rv;
+  }
+
+  auto populateOriginAttributesKey = [&context](const nsString& aKey) {
+    NS_ConvertUTF16toUTF8 key(aKey);
+
+    if (key.IsEmpty()) {
+      return SECSuccess;
+    }
+
+    SECStatus rv = DigestLength(context, key.Length());
+    if (rv != SECSuccess) {
+      return rv;
+    }
+
+    return PK11_DigestOp(context.get(),
+                         BitwiseCast<const unsigned char*>(key.get()),
+                         key.Length());
+  };
+
+  // OCSP should be isolated by firstPartyDomain and partitionKey, but not
+  // by containers.
+  rv = populateOriginAttributesKey(originAttributes.mFirstPartyDomain);
+  if (rv != SECSuccess) {
+    return rv;
+  }
+
+  bool isolateByPartitionKey =
+      originAttributes.mPrivateBrowsingId > 0
+          ? StaticPrefs::privacy_partition_network_state_ocsp_cache_pbmode()
+          : StaticPrefs::privacy_partition_network_state_ocsp_cache();
+  if (isolateByPartitionKey) {
+    rv = populateOriginAttributesKey(originAttributes.mPartitionKey);
+    if (rv != SECSuccess) {
+      return rv;
+    }
+  }
+  uint32_t outLen = 0;
+  rv = PK11_DigestFinal(context.get(), buf, &outLen, SHA384_LENGTH);
+  if (outLen != SHA384_LENGTH) {
+    return SECFailure;
+  }
+  return rv;
+}
+
+Result OCSPCache::Entry::Init(const CertID& aCertID,
+                              const OriginAttributes& aOriginAttributes) {
+  SECStatus srv = CertIDHash(mIDHash, aCertID, aOriginAttributes);
+  if (srv != SECSuccess) {
+    return MapPRErrorCodeToResult(PR_GetError());
+  }
+  return Success;
+}
+
+OCSPCache::OCSPCache() : mMutex("OCSPCache-mutex") {}
+
+OCSPCache::~OCSPCache() { Clear(); }
+
+// Returns false with index in an undefined state if no matching entry was
+// found.
+bool OCSPCache::FindInternal(const CertID& aCertID,
+                             const OriginAttributes& aOriginAttributes,
+                             /*out*/ size_t& index,
+                             const MutexAutoLock& /* aProofOfLock */) {
+  mMutex.AssertCurrentThreadOwns();
+  if (mEntries.length() == 0) {
+    return false;
+  }
+
+  SHA384Buffer idHash;
+  SECStatus rv = CertIDHash(idHash, aCertID, aOriginAttributes);
+  if (rv != SECSuccess) {
+    return false;
+  }
+
+  // mEntries is sorted with the most-recently-used entry at the end.
+  // Thus, searching from the end will often be fastest.
+  index = mEntries.length();
+  while (index > 0) {
+    --index;
+    if (memcmp(mEntries[index]->mIDHash, idHash, SHA384_LENGTH) == 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static inline void LogWithCertID(const char* aMessage, const CertID& aCertID,
+                                 const OriginAttributes& aOriginAttributes) {
+  nsAutoString info = u"firstPartyDomain: "_ns +
+                      aOriginAttributes.mFirstPartyDomain +
+                      u", partitionKey: "_ns + aOriginAttributes.mPartitionKey;
+  MOZ_LOG(gCertVerifierLog, LogLevel::Debug,
+          (aMessage, &aCertID, NS_ConvertUTF16toUTF8(info).get()));
+}
+
+void OCSPCache::MakeMostRecentlyUsed(size_t aIndex,
+                                     const MutexAutoLock& /* aProofOfLock */) {
+  mMutex.AssertCurrentThreadOwns();
+  Entry* entry = mEntries[aIndex];
+  // Since mEntries is sorted with the most-recently-used entry at the end,
+  // aIndex is likely to be near the end, so this is likely to be fast.
+  mEntries.erase(mEntries.begin() + aIndex);
+  // erase() does not shrink or realloc memory, so the append below should
+  // always succeed.
+  MOZ_RELEASE_ASSERT(mEntries.append(entry));
+}
+
+bool OCSPCache::Get(const CertID& aCertID,
+                    const OriginAttributes& aOriginAttributes, Result& aResult,
+                    Time& aValidThrough) {
+  MutexAutoLock lock(mMutex);
+
+  size_t index;
+  if (!FindInternal(aCertID, aOriginAttributes, index, lock)) {
+    LogWithCertID("OCSPCache::Get(%p,\"%s\") not in cache", aCertID,
+                  aOriginAttributes);
+    return false;
+  }
+  LogWithCertID("OCSPCache::Get(%p,\"%s\") in cache", aCertID,
+                aOriginAttributes);
+  aResult = mEntries[index]->mResult;
+  aValidThrough = mEntries[index]->mValidThrough;
+  MakeMostRecentlyUsed(index, lock);
+  return true;
+}
+
+Result OCSPCache::Put(const CertID& aCertID,
+                      const OriginAttributes& aOriginAttributes, Result aResult,
+                      Time aThisUpdate, Time aValidThrough) {
+  MutexAutoLock lock(mMutex);
+
+  size_t index;
+  if (FindInternal(aCertID, aOriginAttributes, index, lock)) {
+    // Never replace an entry indicating a revoked certificate.
+    if (mEntries[index]->mResult == Result::ERROR_REVOKED_CERTIFICATE) {
+      LogWithCertID(
+          "OCSPCache::Put(%p, \"%s\") already in cache as revoked - "
+          "not replacing",
+          aCertID, aOriginAttributes);
+      MakeMostRecentlyUsed(index, lock);
+      return Success;
+    }
+
+    // Never replace a newer entry with an older one unless the older entry
+    // indicates a revoked certificate, which we want to remember.
+    if (mEntries[index]->mThisUpdate > aThisUpdate &&
+        aResult != Result::ERROR_REVOKED_CERTIFICATE) {
+      LogWithCertID(
+          "OCSPCache::Put(%p, \"%s\") already in cache with more "
+          "recent validity - not replacing",
+          aCertID, aOriginAttributes);
+      MakeMostRecentlyUsed(index, lock);
+      return Success;
+    }
+
+    // Only known good responses or responses indicating an unknown
+    // or revoked certificate should replace previously known responses.
+    if (aResult != Success && aResult != Result::ERROR_OCSP_UNKNOWN_CERT &&
+        aResult != Result::ERROR_REVOKED_CERTIFICATE) {
+      LogWithCertID(
+          "OCSPCache::Put(%p, \"%s\") already in cache - not "
+          "replacing with less important status",
+          aCertID, aOriginAttributes);
+      MakeMostRecentlyUsed(index, lock);
+      return Success;
+    }
+
+    LogWithCertID("OCSPCache::Put(%p, \"%s\") already in cache - replacing",
+                  aCertID, aOriginAttributes);
+    mEntries[index]->mResult = aResult;
+    mEntries[index]->mThisUpdate = aThisUpdate;
+    mEntries[index]->mValidThrough = aValidThrough;
+    MakeMostRecentlyUsed(index, lock);
+    return Success;
+  }
+
+  if (mEntries.length() == MaxEntries) {
+    LogWithCertID("OCSPCache::Put(%p, \"%s\") too full - evicting an entry",
+                  aCertID, aOriginAttributes);
+    for (Entry** toEvict = mEntries.begin(); toEvict != mEntries.end();
+         toEvict++) {
+      // Never evict an entry that indicates a revoked or unknokwn certificate,
+      // because revoked responses are more security-critical to remember.
+      if ((*toEvict)->mResult != Result::ERROR_REVOKED_CERTIFICATE &&
+          (*toEvict)->mResult != Result::ERROR_OCSP_UNKNOWN_CERT) {
+        delete *toEvict;
+        mEntries.erase(toEvict);
+        break;
+      }
+    }
+    // Well, we tried, but apparently everything is revoked or unknown.
+    // We don't want to remove a cached revoked or unknown response. If we're
+    // trying to insert a good response, we can just return "successfully"
+    // without doing so. This means we'll lose some speed, but it's not a
+    // security issue. If we're trying to insert a revoked or unknown response,
+    // we can't. We should return with an error that causes the current
+    // verification to fail.
+    if (mEntries.length() == MaxEntries) {
+      return aResult;
+    }
+  }
+
+  Entry* newEntry =
+      new (std::nothrow) Entry(aResult, aThisUpdate, aValidThrough);
+  // Normally we don't have to do this in Gecko, because OOM is fatal.
+  // However, if we want to embed this in another project, OOM might not
+  // be fatal, so handle this case.
+  if (!newEntry) {
+    return Result::FATAL_ERROR_NO_MEMORY;
+  }
+  Result rv = newEntry->Init(aCertID, aOriginAttributes);
+  if (rv != Success) {
+    delete newEntry;
+    return rv;
+  }
+  if (!mEntries.append(newEntry)) {
+    delete newEntry;
+    return Result::FATAL_ERROR_NO_MEMORY;
+  }
+  LogWithCertID("OCSPCache::Put(%p, \"%s\") added to cache", aCertID,
+                aOriginAttributes);
+  return Success;
+}
+
+void OCSPCache::Clear() {
+  MutexAutoLock lock(mMutex);
+  MOZ_LOG(gCertVerifierLog, LogLevel::Debug,
+          ("OCSPCache::Clear: clearing cache"));
+  // First go through and delete the memory being pointed to by the pointers
+  // in the vector.
+  for (Entry** entry = mEntries.begin(); entry < mEntries.end(); entry++) {
+    delete *entry;
+  }
+  // Then remove the pointers themselves.
+  mEntries.clearAndFree();
+}
+
+}  // namespace psm
+}  // namespace mozilla