security/certverifier/OCSPCache.cpp
author Alastor Wu <alwu@mozilla.com>
Tue, 05 Mar 2019 02:06:22 +0000
changeset 516285 dc39216dfad387efd439083045062e323869a428
parent 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1530220 - part1 : allow some non-printalble keys as supported user gesture inputs to activate document. r=masayuki,cpearce a=lizzard `carriage return` and `space` are common keys which user might use to start media, so we should take account them as supported user gesture inputs. As their pseudo char code are zero, we have to check their key code in order to distinguish them from other controls keys such as shift, alt... Differential Revision: https://phabricator.services.mozilla.com/D21253

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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 * 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/.
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/* 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.
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 *     http://www.apache.org/licenses/LICENSE-2.0
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#include "OCSPCache.h"

#include <limits>

#include "NSSCertDBTrustDomain.h"
#include "pk11pub.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.
// The value calculated is SHA384(derIssuer || derPublicKey || serialNumberLen
// || serialNumber || firstPartyDomainLen || firstPartyDomain).
// 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;
  }

  // OCSP should not be isolated by containers.
  NS_ConvertUTF16toUTF8 firstPartyDomain(originAttributes.mFirstPartyDomain);
  if (!firstPartyDomain.IsEmpty()) {
    rv = DigestLength(context, firstPartyDomain.Length());
    if (rv != SECSuccess) {
      return rv;
    }
    rv =
        PK11_DigestOp(context.get(),
                      BitwiseCast<const unsigned char*>(firstPartyDomain.get()),
                      firstPartyDomain.Length());
    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 */) {
  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) {
  NS_ConvertUTF16toUTF8 firstPartyDomain(aOriginAttributes.mFirstPartyDomain);
  MOZ_LOG(gCertVerifierLog, LogLevel::Debug,
          (aMessage, &aCertID, firstPartyDomain.get()));
}

void OCSPCache::MakeMostRecentlyUsed(size_t aIndex,
                                     const MutexAutoLock& /* aProofOfLock */) {
  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