extensions/auth/nsAuthSSPI.cpp

/* vim:set ts=4 sw=4 sts=4 et cindent: */
/* 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/. */

//
// Negotiate Authentication Support Module
//
// Described by IETF Internet draft: draft-brezak-kerberos-http-00.txt
// (formerly draft-brezak-spnego-http-04.txt)
//
// Also described here:
// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsecure/html/http-sso-1.asp
//

#include "nsAuthSSPI.h"
#include "nsDNSService2.h"
#include "nsIServiceManager.h"
#include "nsIDNSService.h"
#include "nsIDNSRecord.h"
#include "nsMemory.h"
#include "nsNetCID.h"
#include "nsCOMPtr.h"
#include "nsICryptoHash.h"
#include "mozilla/Telemetry.h"

#include <windows.h>

#define SEC_SUCCESS(Status) ((Status) >= 0)

#ifndef KERB_WRAP_NO_ENCRYPT
#define KERB_WRAP_NO_ENCRYPT 0x80000001
#endif

#ifndef SECBUFFER_PADDING
#define SECBUFFER_PADDING 9
#endif

#ifndef SECBUFFER_STREAM
#define SECBUFFER_STREAM 10
#endif

//-----------------------------------------------------------------------------

static const wchar_t *const pTypeName[] = {L"Kerberos", L"Negotiate", L"NTLM"};

#ifdef DEBUG
#define CASE_(_x) \
  case _x:        \
    return #_x;
static const char *MapErrorCode(int rc) {
  switch (rc) {
    CASE_(SEC_E_OK)
    CASE_(SEC_I_CONTINUE_NEEDED)
    CASE_(SEC_I_COMPLETE_NEEDED)
    CASE_(SEC_I_COMPLETE_AND_CONTINUE)
    CASE_(SEC_E_INCOMPLETE_MESSAGE)
    CASE_(SEC_I_INCOMPLETE_CREDENTIALS)
    CASE_(SEC_E_INVALID_HANDLE)
    CASE_(SEC_E_TARGET_UNKNOWN)
    CASE_(SEC_E_LOGON_DENIED)
    CASE_(SEC_E_INTERNAL_ERROR)
    CASE_(SEC_E_NO_CREDENTIALS)
    CASE_(SEC_E_NO_AUTHENTICATING_AUTHORITY)
    CASE_(SEC_E_INSUFFICIENT_MEMORY)
    CASE_(SEC_E_INVALID_TOKEN)
  }
  return "<unknown>";
}
#else
#define MapErrorCode(_rc) ""
#endif

//-----------------------------------------------------------------------------

static PSecurityFunctionTableW sspi;

static nsresult InitSSPI() {
  LOG(("  InitSSPI\n"));

  sspi = InitSecurityInterfaceW();
  if (!sspi) {
    LOG(("InitSecurityInterfaceW failed"));
    return NS_ERROR_UNEXPECTED;
  }

  return NS_OK;
}

//-----------------------------------------------------------------------------

nsresult nsAuthSSPI::MakeSN(const char *principal, nsCString &result) {
  nsresult rv;

  nsAutoCString buf(principal);

  // The service name looks like "protocol@hostname", we need to map
  // this to a value that SSPI expects.  To be consistent with IE, we
  // need to map '@' to '/' and canonicalize the hostname.
  int32_t index = buf.FindChar('@');
  if (index == kNotFound) return NS_ERROR_UNEXPECTED;

  nsCOMPtr<nsIDNSService> dnsService =
      do_GetService(NS_DNSSERVICE_CONTRACTID, &rv);
  if (NS_FAILED(rv)) return rv;

  auto dns = static_cast<nsDNSService *>(dnsService.get());

  // This could be expensive if our DNS cache cannot satisfy the request.
  // However, we should have at least hit the OS resolver once prior to
  // reaching this code, so provided the OS resolver has this information
  // cached, we should not have to worry about blocking on this function call
  // for very long.  NOTE: because we ask for the canonical hostname, we
  // might end up requiring extra network activity in cases where the OS
  // resolver might not have enough information to satisfy the request from
  // its cache.  This is not an issue in versions of Windows up to WinXP.
  nsCOMPtr<nsIDNSRecord> record;
  mozilla::OriginAttributes attrs;
  rv = dns->DeprecatedSyncResolve(Substring(buf, index + 1),
                                  nsIDNSService::RESOLVE_CANONICAL_NAME, attrs,
                                  getter_AddRefs(record));
  if (NS_FAILED(rv)) return rv;

  nsAutoCString cname;
  rv = record->GetCanonicalName(cname);
  if (NS_SUCCEEDED(rv)) {
    result = StringHead(buf, index) + NS_LITERAL_CSTRING("/") + cname;
    LOG(("Using SPN of [%s]\n", result.get()));
  }
  return rv;
}

//-----------------------------------------------------------------------------

nsAuthSSPI::nsAuthSSPI(pType package)
    : mServiceFlags(REQ_DEFAULT),
      mMaxTokenLen(0),
      mPackage(package),
      mCertDERData(nullptr),
      mCertDERLength(0) {
  memset(&mCred, 0, sizeof(mCred));
  memset(&mCtxt, 0, sizeof(mCtxt));
}

nsAuthSSPI::~nsAuthSSPI() {
  Reset();

  if (mCred.dwLower || mCred.dwUpper) {
#ifdef __MINGW32__
    (sspi->FreeCredentialsHandle)(&mCred);
#else
    (sspi->FreeCredentialHandle)(&mCred);
#endif
    memset(&mCred, 0, sizeof(mCred));
  }
}

void nsAuthSSPI::Reset() {
  mIsFirst = true;

  if (mCertDERData) {
    free(mCertDERData);
    mCertDERData = nullptr;
    mCertDERLength = 0;
  }

  if (mCtxt.dwLower || mCtxt.dwUpper) {
    (sspi->DeleteSecurityContext)(&mCtxt);
    memset(&mCtxt, 0, sizeof(mCtxt));
  }
}

NS_IMPL_ISUPPORTS(nsAuthSSPI, nsIAuthModule)

NS_IMETHODIMP
nsAuthSSPI::Init(const char *serviceName, uint32_t serviceFlags,
                 const char16_t *domain, const char16_t *username,
                 const char16_t *password) {
  LOG(("  nsAuthSSPI::Init\n"));

  mIsFirst = true;
  mCertDERLength = 0;
  mCertDERData = nullptr;

  // The caller must supply a service name to be used. (For why we now require
  // a service name for NTLM, see bug 487872.)
  NS_ENSURE_TRUE(serviceName && *serviceName, NS_ERROR_INVALID_ARG);

  nsresult rv;

  // XXX lazy initialization like this assumes that we are single threaded
  if (!sspi) {
    rv = InitSSPI();
    if (NS_FAILED(rv)) return rv;
  }
  SEC_WCHAR *package;

  package = (SEC_WCHAR *)pTypeName[(int)mPackage];

  if (mPackage == PACKAGE_TYPE_NTLM) {
    // (bug 535193) For NTLM, just use the uri host, do not do canonical host
    // lookups. The incoming serviceName is in the format: "protocol@hostname",
    // SSPI expects
    // "<service class>/<hostname>", so swap the '@' for a '/'.
    mServiceName.Assign(serviceName);
    int32_t index = mServiceName.FindChar('@');
    if (index == kNotFound) return NS_ERROR_UNEXPECTED;
    mServiceName.Replace(index, 1, '/');
  } else {
    // Kerberos requires the canonical host, MakeSN takes care of this through a
    // DNS lookup.
    rv = MakeSN(serviceName, mServiceName);
    if (NS_FAILED(rv)) return rv;
  }

  mServiceFlags = serviceFlags;

  SECURITY_STATUS rc;

  PSecPkgInfoW pinfo;
  rc = (sspi->QuerySecurityPackageInfoW)(package, &pinfo);
  if (rc != SEC_E_OK) {
    LOG(("%s package not found\n", package));
    return NS_ERROR_UNEXPECTED;
  }
  mMaxTokenLen = pinfo->cbMaxToken;
  (sspi->FreeContextBuffer)(pinfo);

  MS_TimeStamp useBefore;

  SEC_WINNT_AUTH_IDENTITY_W ai;
  SEC_WINNT_AUTH_IDENTITY_W *pai = nullptr;

  // domain, username, and password will be null if nsHttpNTLMAuth's
  // ChallengeReceived returns false for identityInvalid. Use default
  // credentials in this case by passing null for pai.
  if (username && password) {
    // Keep a copy of these strings for the duration
    mUsername.Assign(username);
    mPassword.Assign(password);
    mDomain.Assign(domain);
    ai.Domain = reinterpret_cast<unsigned short *>(mDomain.BeginWriting());
    ai.DomainLength = mDomain.Length();
    ai.User = reinterpret_cast<unsigned short *>(mUsername.BeginWriting());
    ai.UserLength = mUsername.Length();
    ai.Password = reinterpret_cast<unsigned short *>(mPassword.BeginWriting());
    ai.PasswordLength = mPassword.Length();
    ai.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;
    pai = &ai;
  }

  rc = (sspi->AcquireCredentialsHandleW)(nullptr, package, SECPKG_CRED_OUTBOUND,
                                         nullptr, pai, nullptr, nullptr, &mCred,
                                         &useBefore);
  if (rc != SEC_E_OK) return NS_ERROR_UNEXPECTED;

  static bool sTelemetrySent = false;
  if (!sTelemetrySent) {
    mozilla::Telemetry::Accumulate(mozilla::Telemetry::NTLM_MODULE_USED_2,
                                   serviceFlags & nsIAuthModule::REQ_PROXY_AUTH
                                       ? NTLM_MODULE_WIN_API_PROXY
                                       : NTLM_MODULE_WIN_API_DIRECT);
    sTelemetrySent = true;
  }

  LOG(("AcquireCredentialsHandle() succeeded.\n"));
  return NS_OK;
}

// The arguments inToken and inTokenLen are used to pass in the server
// certificate (when available) in the first call of the function. The
// second time these arguments hold an input token.
NS_IMETHODIMP
nsAuthSSPI::GetNextToken(const void *inToken, uint32_t inTokenLen,
                         void **outToken, uint32_t *outTokenLen) {
  // String for end-point bindings.
  const char end_point[] = "tls-server-end-point:";
  const int end_point_length = sizeof(end_point) - 1;
  const int hash_size = 32;  // Size of a SHA256 hash.
  const int cbt_size = hash_size + end_point_length;

  SECURITY_STATUS rc;
  MS_TimeStamp ignored;

  DWORD ctxAttr, ctxReq = 0;
  CtxtHandle *ctxIn;
  SecBufferDesc ibd, obd;
  // Optional second input buffer for the CBT (Channel Binding Token)
  SecBuffer ib[2], ob;
  // Pointer to the block of memory that stores the CBT
  char *sspi_cbt = nullptr;
  SEC_CHANNEL_BINDINGS pendpoint_binding;

  LOG(("entering nsAuthSSPI::GetNextToken()\n"));

  if (!mCred.dwLower && !mCred.dwUpper) {
    LOG(("nsAuthSSPI::GetNextToken(), not initialized. exiting."));
    return NS_ERROR_NOT_INITIALIZED;
  }

  if (mServiceFlags & REQ_DELEGATE) ctxReq |= ISC_REQ_DELEGATE;
  if (mServiceFlags & REQ_MUTUAL_AUTH) ctxReq |= ISC_REQ_MUTUAL_AUTH;

  if (inToken) {
    if (mIsFirst) {
      // First time if it comes with a token,
      // the token represents the server certificate.
      mIsFirst = false;
      mCertDERLength = inTokenLen;
      mCertDERData = moz_xmalloc(inTokenLen);
      if (!mCertDERData) return NS_ERROR_OUT_OF_MEMORY;
      memcpy(mCertDERData, inToken, inTokenLen);

      // We are starting a new authentication sequence.
      // If we have already initialized our
      // security context, then we're in trouble because it means that the
      // first sequence failed.  We need to bail or else we might end up in
      // an infinite loop.
      if (mCtxt.dwLower || mCtxt.dwUpper) {
        LOG(("Cannot restart authentication sequence!"));
        return NS_ERROR_UNEXPECTED;
      }
      ctxIn = nullptr;
      // The certificate needs to be erased before being passed
      // to InitializeSecurityContextW().
      inToken = nullptr;
      inTokenLen = 0;
    } else {
      ibd.ulVersion = SECBUFFER_VERSION;
      ibd.cBuffers = 0;
      ibd.pBuffers = ib;

      // If we have stored a certificate, the Channel Binding Token
      // needs to be generated and sent in the first input buffer.
      if (mCertDERLength > 0) {
        // First we create a proper Endpoint Binding structure.
        pendpoint_binding.dwInitiatorAddrType = 0;
        pendpoint_binding.cbInitiatorLength = 0;
        pendpoint_binding.dwInitiatorOffset = 0;
        pendpoint_binding.dwAcceptorAddrType = 0;
        pendpoint_binding.cbAcceptorLength = 0;
        pendpoint_binding.dwAcceptorOffset = 0;
        pendpoint_binding.cbApplicationDataLength = cbt_size;
        pendpoint_binding.dwApplicationDataOffset =
            sizeof(SEC_CHANNEL_BINDINGS);

        // Then add it to the array of sec buffers accordingly.
        ib[ibd.cBuffers].BufferType = SECBUFFER_CHANNEL_BINDINGS;
        ib[ibd.cBuffers].cbBuffer = pendpoint_binding.cbApplicationDataLength +
                                    pendpoint_binding.dwApplicationDataOffset;

        sspi_cbt = (char *)moz_xmalloc(ib[ibd.cBuffers].cbBuffer);
        if (!sspi_cbt) {
          return NS_ERROR_OUT_OF_MEMORY;
        }

        // Helper to write in the memory block that stores the CBT
        char *sspi_cbt_ptr = sspi_cbt;

        ib[ibd.cBuffers].pvBuffer = sspi_cbt;
        ibd.cBuffers++;

        memcpy(sspi_cbt_ptr, &pendpoint_binding,
               pendpoint_binding.dwApplicationDataOffset);
        sspi_cbt_ptr += pendpoint_binding.dwApplicationDataOffset;

        memcpy(sspi_cbt_ptr, end_point, end_point_length);
        sspi_cbt_ptr += end_point_length;

        // Start hashing. We are always doing SHA256, but depending
        // on the certificate, a different alogirthm might be needed.
        nsAutoCString hashString;

        nsresult rv;
        nsCOMPtr<nsICryptoHash> crypto;
        crypto = do_CreateInstance(NS_CRYPTO_HASH_CONTRACTID, &rv);
        if (NS_SUCCEEDED(rv)) rv = crypto->Init(nsICryptoHash::SHA256);
        if (NS_SUCCEEDED(rv))
          rv = crypto->Update((unsigned char *)mCertDERData, mCertDERLength);
        if (NS_SUCCEEDED(rv)) rv = crypto->Finish(false, hashString);
        if (NS_FAILED(rv)) {
          free(mCertDERData);
          mCertDERData = nullptr;
          mCertDERLength = 0;
          free(sspi_cbt);
          return rv;
        }

        // Once the hash has been computed, we store it in memory right
        // after the Endpoint structure and the "tls-server-end-point:"
        // char array.
        memcpy(sspi_cbt_ptr, hashString.get(), hash_size);

        // Free memory used to store the server certificate
        free(mCertDERData);
        mCertDERData = nullptr;
        mCertDERLength = 0;
      }  // End of CBT computation.

      // We always need this SECBUFFER.
      ib[ibd.cBuffers].BufferType = SECBUFFER_TOKEN;
      ib[ibd.cBuffers].cbBuffer = inTokenLen;
      ib[ibd.cBuffers].pvBuffer = (void *)inToken;
      ibd.cBuffers++;
      ctxIn = &mCtxt;
    }
  } else {  // First time and without a token (no server certificate)
    // We are starting a new authentication sequence.  If we have already
    // initialized our security context, then we're in trouble because it
    // means that the first sequence failed.  We need to bail or else we
    // might end up in an infinite loop.
    if (mCtxt.dwLower || mCtxt.dwUpper || mCertDERData || mCertDERLength) {
      LOG(("Cannot restart authentication sequence!"));
      return NS_ERROR_UNEXPECTED;
    }
    ctxIn = nullptr;
    mIsFirst = false;
  }

  obd.ulVersion = SECBUFFER_VERSION;
  obd.cBuffers = 1;
  obd.pBuffers = &ob;
  ob.BufferType = SECBUFFER_TOKEN;
  ob.cbBuffer = mMaxTokenLen;
  ob.pvBuffer = moz_xmalloc(ob.cbBuffer);
  if (!ob.pvBuffer) {
    if (sspi_cbt) free(sspi_cbt);
    return NS_ERROR_OUT_OF_MEMORY;
  }
  memset(ob.pvBuffer, 0, ob.cbBuffer);

  NS_ConvertUTF8toUTF16 wSN(mServiceName);
  SEC_WCHAR *sn = (SEC_WCHAR *)wSN.get();

  rc = (sspi->InitializeSecurityContextW)(
      &mCred, ctxIn, sn, ctxReq, 0, SECURITY_NATIVE_DREP,
      inToken ? &ibd : nullptr, 0, &mCtxt, &obd, &ctxAttr, &ignored);
  if (rc == SEC_I_CONTINUE_NEEDED || rc == SEC_E_OK) {
    if (rc == SEC_E_OK)
      LOG(("InitializeSecurityContext: succeeded.\n"));
    else
      LOG(("InitializeSecurityContext: continue.\n"));

    if (sspi_cbt) free(sspi_cbt);

    if (!ob.cbBuffer) {
      free(ob.pvBuffer);
      ob.pvBuffer = nullptr;
    }
    *outToken = ob.pvBuffer;
    *outTokenLen = ob.cbBuffer;

    if (rc == SEC_E_OK) return NS_SUCCESS_AUTH_FINISHED;

    return NS_OK;
  }

  LOG(("InitializeSecurityContext failed [rc=%d:%s]\n", rc, MapErrorCode(rc)));
  Reset();
  free(ob.pvBuffer);
  return NS_ERROR_FAILURE;
}

NS_IMETHODIMP
nsAuthSSPI::Unwrap(const void *inToken, uint32_t inTokenLen, void **outToken,
                   uint32_t *outTokenLen) {
  SECURITY_STATUS rc;
  SecBufferDesc ibd;
  SecBuffer ib[2];

  ibd.cBuffers = 2;
  ibd.pBuffers = ib;
  ibd.ulVersion = SECBUFFER_VERSION;

  // SSPI Buf
  ib[0].BufferType = SECBUFFER_STREAM;
  ib[0].cbBuffer = inTokenLen;
  ib[0].pvBuffer = moz_xmalloc(ib[0].cbBuffer);
  if (!ib[0].pvBuffer) return NS_ERROR_OUT_OF_MEMORY;

  memcpy(ib[0].pvBuffer, inToken, inTokenLen);

  // app data
  ib[1].BufferType = SECBUFFER_DATA;
  ib[1].cbBuffer = 0;
  ib[1].pvBuffer = nullptr;

  rc = (sspi->DecryptMessage)(&mCtxt, &ibd,
                              0,  // no sequence numbers
                              nullptr);

  if (SEC_SUCCESS(rc)) {
    // check if ib[1].pvBuffer is really just ib[0].pvBuffer, in which
    // case we can let the caller free it. Otherwise, we need to
    // clone it, and free the original
    if (ib[0].pvBuffer == ib[1].pvBuffer) {
      *outToken = ib[1].pvBuffer;
    } else {
      *outToken = nsMemory::Clone(ib[1].pvBuffer, ib[1].cbBuffer);
      free(ib[0].pvBuffer);
      if (!*outToken) return NS_ERROR_OUT_OF_MEMORY;
    }
    *outTokenLen = ib[1].cbBuffer;
  } else
    free(ib[0].pvBuffer);

  if (!SEC_SUCCESS(rc)) return NS_ERROR_FAILURE;

  return NS_OK;
}

// utility class used to free memory on exit
class secBuffers {
 public:
  SecBuffer ib[3];

  secBuffers() { memset(&ib, 0, sizeof(ib)); }

  ~secBuffers() {
    if (ib[0].pvBuffer) free(ib[0].pvBuffer);

    if (ib[1].pvBuffer) free(ib[1].pvBuffer);

    if (ib[2].pvBuffer) free(ib[2].pvBuffer);
  }
};

NS_IMETHODIMP
nsAuthSSPI::Wrap(const void *inToken, uint32_t inTokenLen, bool confidential,
                 void **outToken, uint32_t *outTokenLen) {
  SECURITY_STATUS rc;

  SecBufferDesc ibd;
  secBuffers bufs;
  SecPkgContext_Sizes sizes;

  rc = (sspi->QueryContextAttributesW)(&mCtxt, SECPKG_ATTR_SIZES, &sizes);

  if (!SEC_SUCCESS(rc)) return NS_ERROR_FAILURE;

  ibd.cBuffers = 3;
  ibd.pBuffers = bufs.ib;
  ibd.ulVersion = SECBUFFER_VERSION;

  // SSPI
  bufs.ib[0].cbBuffer = sizes.cbSecurityTrailer;
  bufs.ib[0].BufferType = SECBUFFER_TOKEN;
  bufs.ib[0].pvBuffer = moz_xmalloc(sizes.cbSecurityTrailer);

  if (!bufs.ib[0].pvBuffer) return NS_ERROR_OUT_OF_MEMORY;

  // APP Data
  bufs.ib[1].BufferType = SECBUFFER_DATA;
  bufs.ib[1].pvBuffer = moz_xmalloc(inTokenLen);
  bufs.ib[1].cbBuffer = inTokenLen;

  if (!bufs.ib[1].pvBuffer) return NS_ERROR_OUT_OF_MEMORY;

  memcpy(bufs.ib[1].pvBuffer, inToken, inTokenLen);

  // SSPI
  bufs.ib[2].BufferType = SECBUFFER_PADDING;
  bufs.ib[2].cbBuffer = sizes.cbBlockSize;
  bufs.ib[2].pvBuffer = moz_xmalloc(bufs.ib[2].cbBuffer);

  if (!bufs.ib[2].pvBuffer) return NS_ERROR_OUT_OF_MEMORY;

  rc = (sspi->EncryptMessage)(&mCtxt, confidential ? 0 : KERB_WRAP_NO_ENCRYPT,
                              &ibd, 0);

  if (SEC_SUCCESS(rc)) {
    int len = bufs.ib[0].cbBuffer + bufs.ib[1].cbBuffer + bufs.ib[2].cbBuffer;
    char *p = (char *)moz_xmalloc(len);

    if (!p) return NS_ERROR_OUT_OF_MEMORY;

    *outToken = (void *)p;
    *outTokenLen = len;

    memcpy(p, bufs.ib[0].pvBuffer, bufs.ib[0].cbBuffer);
    p += bufs.ib[0].cbBuffer;

    memcpy(p, bufs.ib[1].pvBuffer, bufs.ib[1].cbBuffer);
    p += bufs.ib[1].cbBuffer;

    memcpy(p, bufs.ib[2].pvBuffer, bufs.ib[2].cbBuffer);

    return NS_OK;
  }

  return NS_ERROR_FAILURE;
}