/** @file
  RFC3161 Timestamp Countersignature Verification over OpenSSL.
  The timestamp is generated by a TimeStamping Authority (TSA) and asserts that a
  publisher's signature existed before the specified time. The timestamp extends
  the lifetime of the signature when a signing certificate expires or is later
  revoked.

Copyright (c) 2014 - 2017, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "InternalCryptLib.h"

#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/pkcs7.h>

//
// OID ASN.1 Value for SPC_RFC3161_OBJID ("1.3.6.1.4.1.311.3.3.1")
//
GLOBAL_REMOVE_IF_UNREFERENCED const UINT8  mSpcRFC3161OidValue[] = {
  0x2b, 0x06, 0x01, 0x04, 0x01, 0x82, 0x37, 0x03, 0x03, 0x01
};

///
/// The messageImprint field SHOULD contain the hash of the datum to be
/// time-stamped.  The hash is represented as an OCTET STRING.  Its
/// length MUST match the length of the hash value for that algorithm
/// (e.g., 20 bytes for SHA-1 or 16 bytes for MD5).
///
/// MessageImprint ::= SEQUENCE  {
///   hashAlgorithm                AlgorithmIdentifier,
///   hashedMessage                OCTET STRING  }
///
typedef struct {
  X509_ALGOR           *HashAlgorithm;
  ASN1_OCTET_STRING    *HashedMessage;
} TS_MESSAGE_IMPRINT;

//
// ASN.1 Functions for TS_MESSAGE_IMPRINT
//
GLOBAL_REMOVE_IF_UNREFERENCED
DECLARE_ASN1_FUNCTIONS (
  TS_MESSAGE_IMPRINT
  )
ASN1_SEQUENCE (TS_MESSAGE_IMPRINT) =
{
  ASN1_SIMPLE (TS_MESSAGE_IMPRINT, HashAlgorithm, X509_ALGOR),
  ASN1_SIMPLE (TS_MESSAGE_IMPRINT, HashedMessage, ASN1_OCTET_STRING)
}

ASN1_SEQUENCE_END (TS_MESSAGE_IMPRINT)
IMPLEMENT_ASN1_FUNCTIONS (TS_MESSAGE_IMPRINT)

///
/// Accuracy represents the time deviation around the UTC time contained
/// in GeneralizedTime of time-stamp token.
///
/// Accuracy ::= SEQUENCE {
///       seconds        INTEGER              OPTIONAL,
///       millis     [0] INTEGER  (1..999)    OPTIONAL,
///       micros     [1] INTEGER  (1..999)    OPTIONAL  }
///
typedef struct {
  ASN1_INTEGER    *Seconds;
  ASN1_INTEGER    *Millis;
  ASN1_INTEGER    *Micros;
} TS_ACCURACY;

//
// ASN.1 Functions for TS_ACCURACY
//
GLOBAL_REMOVE_IF_UNREFERENCED
DECLARE_ASN1_FUNCTIONS (
  TS_ACCURACY
  )
ASN1_SEQUENCE (TS_ACCURACY) =
{
  ASN1_OPT (TS_ACCURACY,     Seconds, ASN1_INTEGER),
  ASN1_IMP_OPT (TS_ACCURACY, Millis,  ASN1_INTEGER, 0),
  ASN1_IMP_OPT (TS_ACCURACY, Micros,  ASN1_INTEGER, 1)
}

ASN1_SEQUENCE_END (TS_ACCURACY)
IMPLEMENT_ASN1_FUNCTIONS (TS_ACCURACY)

///
/// The timestamp token info resulting from a successful timestamp request,
/// as defined in RFC 3161.
///
///  TSTInfo ::= SEQUENCE  {
///     version                      INTEGER  { v1(1) },
///     policy                       TSAPolicyId,
///     messageImprint               MessageImprint,
///       -- MUST have the same value as the similar field in
///       -- TimeStampReq
///     serialNumber                 INTEGER,
///       -- Time-Stamping users MUST be ready to accommodate integers
///       -- up to 160 bits.
///     genTime                      GeneralizedTime,
///     accuracy                     Accuracy                 OPTIONAL,
///     ordering                     BOOLEAN             DEFAULT FALSE,
///     nonce                        INTEGER                  OPTIONAL,
///       -- MUST be present if the similar field was present
///       -- in TimeStampReq.  In that case it MUST have the same value.
///     tsa                          [0] GeneralName          OPTIONAL,
///     extensions                   [1] IMPLICIT Extensions   OPTIONAL  }
///
typedef struct {
  ASN1_INTEGER            *Version;
  ASN1_OBJECT             *Policy;
  TS_MESSAGE_IMPRINT      *MessageImprint;
  ASN1_INTEGER            *SerialNumber;
  ASN1_GENERALIZEDTIME    *GenTime;
  TS_ACCURACY             *Accuracy;
  ASN1_BOOLEAN            Ordering;
  ASN1_INTEGER            *Nonce;
  GENERAL_NAME            *Tsa;
  STACK_OF (X509_EXTENSION)  *Extensions;
} TS_TST_INFO;

//
// ASN.1 Functions for TS_TST_INFO
//
GLOBAL_REMOVE_IF_UNREFERENCED
DECLARE_ASN1_FUNCTIONS (
  TS_TST_INFO
  )
ASN1_SEQUENCE (TS_TST_INFO) =
{
  ASN1_SIMPLE (TS_TST_INFO,              Version,        ASN1_INTEGER),
  ASN1_SIMPLE (TS_TST_INFO,              Policy,         ASN1_OBJECT),
  ASN1_SIMPLE (TS_TST_INFO,              MessageImprint, TS_MESSAGE_IMPRINT),
  ASN1_SIMPLE (TS_TST_INFO,              SerialNumber,   ASN1_INTEGER),
  ASN1_SIMPLE (TS_TST_INFO,              GenTime,        ASN1_GENERALIZEDTIME),
  ASN1_OPT (TS_TST_INFO,                 Accuracy,       TS_ACCURACY),
  ASN1_OPT (TS_TST_INFO,                 Ordering,       ASN1_FBOOLEAN),
  ASN1_OPT (TS_TST_INFO,                 Nonce,          ASN1_INTEGER),
  ASN1_EXP_OPT (TS_TST_INFO,             Tsa,            GENERAL_NAME,         0),
  ASN1_IMP_SEQUENCE_OF_OPT (TS_TST_INFO, Extensions,     X509_EXTENSION,       1)
}

ASN1_SEQUENCE_END (TS_TST_INFO)
IMPLEMENT_ASN1_FUNCTIONS (TS_TST_INFO)

/**
  Convert ASN.1 GeneralizedTime to EFI Time.

  @param[in]  Asn1Time         Pointer to the ASN.1 GeneralizedTime to be converted.
  @param[out] SigningTime      Return the corresponding EFI Time.

  @retval  TRUE   The time conversion succeeds.
  @retval  FALSE  Invalid parameters.

**/
STATIC
BOOLEAN
ConvertAsn1TimeToEfiTime (
  IN  ASN1_TIME  *Asn1Time,
  OUT EFI_TIME   *EfiTime
  )
{
  CONST CHAR8  *Str;
  UINTN        Index;

  if ((Asn1Time == NULL) || (EfiTime == NULL)) {
    return FALSE;
  }

  Str = (CONST CHAR8 *)Asn1Time->data;
  SetMem (EfiTime, sizeof (EFI_TIME), 0);

  Index = 0;
  if (Asn1Time->type == V_ASN1_UTCTIME) {
    /* two digit year */
    EfiTime->Year  = (Str[Index++] - '0') * 10;
    EfiTime->Year += (Str[Index++] - '0');
    if (EfiTime->Year < 70) {
      EfiTime->Year += 100;
    }
  } else if (Asn1Time->type == V_ASN1_GENERALIZEDTIME) {
    /* four digit year */
    EfiTime->Year  = (Str[Index++] - '0') * 1000;
    EfiTime->Year += (Str[Index++] - '0') * 100;
    EfiTime->Year += (Str[Index++] - '0') * 10;
    EfiTime->Year += (Str[Index++] - '0');
    if ((EfiTime->Year < 1900) || (EfiTime->Year > 9999)) {
      return FALSE;
    }
  }

  EfiTime->Month  = (Str[Index++] - '0') * 10;
  EfiTime->Month += (Str[Index++] - '0');
  if ((EfiTime->Month < 1) || (EfiTime->Month > 12)) {
    return FALSE;
  }

  EfiTime->Day  = (Str[Index++] - '0') * 10;
  EfiTime->Day += (Str[Index++] - '0');
  if ((EfiTime->Day < 1) || (EfiTime->Day > 31)) {
    return FALSE;
  }

  EfiTime->Hour  = (Str[Index++] - '0') * 10;
  EfiTime->Hour += (Str[Index++] - '0');
  if (EfiTime->Hour > 23) {
    return FALSE;
  }

  EfiTime->Minute  = (Str[Index++] - '0') * 10;
  EfiTime->Minute += (Str[Index++] - '0');
  if (EfiTime->Minute > 59) {
    return FALSE;
  }

  EfiTime->Second  = (Str[Index++] - '0') * 10;
  EfiTime->Second += (Str[Index++] - '0');
  if (EfiTime->Second > 59) {
    return FALSE;
  }

  /* Note: we did not adjust the time based on time zone information */

  return TRUE;
}

/**

  Check the validity of TimeStamp Token Information.

  @param[in]  TstInfo          Pointer to the TS_TST_INFO structure.
  @param[in]  TimestampedData  Pointer to the data to be time-stamped.
  @param[in]  DataSize         Size of timestamped data in bytes.

  @retval  TRUE   The TimeStamp Token Information is valid.
  @retval  FALSE  Invalid TimeStamp Token Information.

**/
STATIC
BOOLEAN
CheckTSTInfo (
  IN  CONST TS_TST_INFO  *TstInfo,
  IN  CONST UINT8        *TimestampedData,
  IN  UINTN              DataSize
  )
{
  BOOLEAN             Status;
  TS_MESSAGE_IMPRINT  *Imprint;
  X509_ALGOR          *HashAlgo;
  CONST EVP_MD        *Md;
  EVP_MD_CTX          *MdCtx;
  UINTN               MdSize;
  UINT8               *HashedMsg;

  //
  // Initialization
  //
  Status    = FALSE;
  HashAlgo  = NULL;
  HashedMsg = NULL;
  MdCtx     = NULL;

  //
  // -- Check version number of Timestamp:
  //   The version field (currently v1) describes the version of the time-stamp token.
  //   Conforming time-stamping servers MUST be able to provide version 1 time-stamp tokens.
  //
  if ((ASN1_INTEGER_get (TstInfo->Version)) != 1) {
    return FALSE;
  }

  //
  // -- Check Policies
  //   The policy field MUST indicate the TSA's policy under which the response was produced.
  //
  if (TstInfo->Policy == NULL) {
    /// NOTE: Need to check if the requested and returned policies.
    ///       We have no information about the Requested TSA Policy.
    return FALSE;
  }

  //
  // -- Compute & Check Message Imprint
  //
  Imprint  = TstInfo->MessageImprint;
  HashAlgo = X509_ALGOR_dup (Imprint->HashAlgorithm);

  Md = EVP_get_digestbyobj (HashAlgo->algorithm);
  if (Md == NULL) {
    goto _Exit;
  }

  MdSize    = EVP_MD_size (Md);
  HashedMsg = AllocateZeroPool (MdSize);
  if (HashedMsg == NULL) {
    goto _Exit;
  }

  MdCtx = EVP_MD_CTX_new ();
  if (MdCtx == NULL) {
    goto _Exit;
  }

  if ((EVP_DigestInit_ex (MdCtx, Md, NULL) != 1) ||
      (EVP_DigestUpdate (MdCtx, TimestampedData, DataSize) != 1) ||
      (EVP_DigestFinal (MdCtx, HashedMsg, NULL) != 1))
  {
    goto _Exit;
  }

  if ((MdSize == (UINTN)ASN1_STRING_length (Imprint->HashedMessage)) &&
      (CompareMem (HashedMsg, ASN1_STRING_get0_data (Imprint->HashedMessage), MdSize) != 0))
  {
    goto _Exit;
  }

  //
  // -- Check Nonces
  //
  if (TstInfo->Nonce != NULL) {
    //
    // Nonces is optional, No error if no nonce is returned;
    //
  }

  //
  // -- Check if the TSA name and signer certificate is matched.
  //
  if (TstInfo->Tsa != NULL) {
    //
    //  Ignored the optional Tsa field checking.
    //
  }

  Status = TRUE;

_Exit:
  X509_ALGOR_free (HashAlgo);
  EVP_MD_CTX_free (MdCtx);
  if (HashedMsg != NULL) {
    FreePool (HashedMsg);
  }

  return Status;
}

/**
  Verifies the validity of a TimeStamp Token as described in RFC 3161 ("Internet
  X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)").

  If TSToken is NULL, then return FALSE.
  If TimestampedData is NULL, then return FALSE.

  @param[in]  TSToken          Pointer to the RFC3161 TimeStamp Token, which is generated
                               by a TSA and located in the software publisher's SignerInfo
                               structure.
  @param[in]  TokenSize        Size of the TimeStamp Token in bytes.
  @param[in]  TsaCert          Pointer to a trusted/root TSA certificate encoded in DER.
  @param[in]  CertSize         Size of the trusted TSA certificate in bytes.
  @param[in]  TimestampedData  Pointer to the data to be time-stamped.
  @param[in]  DataSize         Size of timestamped data in bytes.
  @param[out] SigningTime      Return the time of timestamp generation time if the timestamp
                               signature is valid.

  @retval  TRUE   The specified timestamp token is valid.
  @retval  FALSE  Invalid timestamp token.

**/
STATIC
BOOLEAN
TimestampTokenVerify (
  IN  CONST UINT8  *TSToken,
  IN  UINTN        TokenSize,
  IN  CONST UINT8  *TsaCert,
  IN  UINTN        CertSize,
  IN  CONST UINT8  *TimestampedData,
  IN  UINTN        DataSize,
  OUT EFI_TIME     *SigningTime
  )
{
  BOOLEAN      Status;
  CONST UINT8  *TokenTemp;
  PKCS7        *Pkcs7;
  X509         *Cert;
  CONST UINT8  *CertTemp;
  X509_STORE   *CertStore;
  BIO          *OutBio;
  UINT8        *TstData;
  UINTN        TstSize;
  CONST UINT8  *TstTemp;
  TS_TST_INFO  *TstInfo;

  Status = FALSE;

  //
  // Check input parameters
  //
  if ((TSToken == NULL) || (TsaCert == NULL) || (TimestampedData == NULL) ||
      (TokenSize > INT_MAX) || (CertSize > INT_MAX) || (DataSize > INT_MAX))
  {
    return FALSE;
  }

  //
  // Initializations
  //
  if (SigningTime != NULL) {
    SetMem (SigningTime, sizeof (EFI_TIME), 0);
  }

  Pkcs7     = NULL;
  Cert      = NULL;
  CertStore = NULL;
  OutBio    = NULL;
  TstData   = NULL;
  TstInfo   = NULL;

  //
  // TimeStamp Token should contain one valid DER-encoded ASN.1 PKCS#7 structure.
  //
  TokenTemp = TSToken;
  Pkcs7     = d2i_PKCS7 (NULL, (const unsigned char **)&TokenTemp, (int)TokenSize);
  if (Pkcs7 == NULL) {
    goto _Exit;
  }

  //
  // The timestamp signature (TSA's response) will be one PKCS#7 signed data.
  //
  if (!PKCS7_type_is_signed (Pkcs7)) {
    goto _Exit;
  }

  //
  // Read the trusted TSA certificate (DER-encoded), and Construct X509 Certificate.
  //
  CertTemp = TsaCert;
  Cert     = d2i_X509 (NULL, &CertTemp, (long)CertSize);
  if (Cert == NULL) {
    goto _Exit;
  }

  //
  // Setup X509 Store for trusted certificate.
  //
  CertStore = X509_STORE_new ();
  if ((CertStore == NULL) || !(X509_STORE_add_cert (CertStore, Cert))) {
    goto _Exit;
  }

  //
  // Allow partial certificate chains, terminated by a non-self-signed but
  // still trusted intermediate certificate. Also disable time checks.
  //
  X509_STORE_set_flags (
    CertStore,
    X509_V_FLAG_PARTIAL_CHAIN | X509_V_FLAG_NO_CHECK_TIME
    );

  X509_STORE_set_purpose (CertStore, X509_PURPOSE_ANY);

  //
  // Verifies the PKCS#7 signedData structure, and output the signed contents.
  //
  OutBio = BIO_new (BIO_s_mem ());
  if (OutBio == NULL) {
    goto _Exit;
  }

  if (!PKCS7_verify (Pkcs7, NULL, CertStore, NULL, OutBio, PKCS7_BINARY)) {
    goto _Exit;
  }

  //
  // Read the signed contents detached in timestamp signature.
  //
  TstData = AllocateZeroPool (2048);
  if (TstData == NULL) {
    goto _Exit;
  }

  TstSize = BIO_read (OutBio, (void *)TstData, 2048);

  //
  // Construct TS_TST_INFO structure from the signed contents.
  //
  TstTemp = TstData;
  TstInfo = d2i_TS_TST_INFO (
              NULL,
              (const unsigned char **)&TstTemp,
              (int)TstSize
              );
  if (TstInfo == NULL) {
    goto _Exit;
  }

  //
  // Check TS_TST_INFO structure.
  //
  Status = CheckTSTInfo (TstInfo, TimestampedData, DataSize);
  if (!Status) {
    goto _Exit;
  }

  //
  // Retrieve the signing time from TS_TST_INFO structure.
  //
  if (SigningTime != NULL) {
    SetMem (SigningTime, sizeof (EFI_TIME), 0);
    Status = ConvertAsn1TimeToEfiTime (TstInfo->GenTime, SigningTime);
  }

_Exit:
  //
  // Release Resources
  //
  PKCS7_free (Pkcs7);
  X509_free (Cert);
  X509_STORE_free (CertStore);
  BIO_free (OutBio);
  TS_TST_INFO_free (TstInfo);

  if (TstData != NULL) {
    FreePool (TstData);
  }

  return Status;
}

/**
  Verifies the validity of a RFC3161 Timestamp CounterSignature embedded in PE/COFF Authenticode
  signature.

  If AuthData is NULL, then return FALSE.

  @param[in]  AuthData     Pointer to the Authenticode Signature retrieved from signed
                           PE/COFF image to be verified.
  @param[in]  DataSize     Size of the Authenticode Signature in bytes.
  @param[in]  TsaCert      Pointer to a trusted/root TSA certificate encoded in DER, which
                           is used for TSA certificate chain verification.
  @param[in]  CertSize     Size of the trusted certificate in bytes.
  @param[out] SigningTime  Return the time of timestamp generation time if the timestamp
                           signature is valid.

  @retval  TRUE   The specified Authenticode includes a valid RFC3161 Timestamp CounterSignature.
  @retval  FALSE  No valid RFC3161 Timestamp CounterSignature in the specified Authenticode data.

**/
BOOLEAN
EFIAPI
ImageTimestampVerify (
  IN  CONST UINT8  *AuthData,
  IN  UINTN        DataSize,
  IN  CONST UINT8  *TsaCert,
  IN  UINTN        CertSize,
  OUT EFI_TIME     *SigningTime
  )
{
  BOOLEAN      Status;
  PKCS7        *Pkcs7;
  CONST UINT8  *Temp;

  STACK_OF (PKCS7_SIGNER_INFO)  *SignerInfos;
  PKCS7_SIGNER_INFO  *SignInfo;
  UINTN              Index;

  STACK_OF (X509_ATTRIBUTE)     *Sk;
  X509_ATTRIBUTE     *Xa;
  ASN1_OBJECT        *XaObj;
  ASN1_TYPE          *Asn1Type;
  ASN1_OCTET_STRING  *EncDigest;
  UINT8              *TSToken;
  UINTN              TokenSize;

  //
  // Input Parameters Checking.
  //
  if ((AuthData == NULL) || (TsaCert == NULL)) {
    return FALSE;
  }

  if ((DataSize > INT_MAX) || (CertSize > INT_MAX)) {
    return FALSE;
  }

  //
  // Register & Initialize necessary digest algorithms for PKCS#7 Handling.
  //
  if ((EVP_add_digest (EVP_md5 ()) == 0) || (EVP_add_digest (EVP_sha1 ()) == 0) ||
      (EVP_add_digest (EVP_sha256 ()) == 0) || ((EVP_add_digest_alias (SN_sha1WithRSAEncryption, SN_sha1WithRSA)) == 0))
  {
    return FALSE;
  }

  //
  // Initialization.
  //
  Status   = FALSE;
  Pkcs7    = NULL;
  SignInfo = NULL;

  //
  // Decode ASN.1-encoded Authenticode data into PKCS7 structure.
  //
  Temp  = AuthData;
  Pkcs7 = d2i_PKCS7 (NULL, (const unsigned char **)&Temp, (int)DataSize);
  if (Pkcs7 == NULL) {
    goto _Exit;
  }

  //
  // Check if there is one and only one signer.
  //
  SignerInfos = PKCS7_get_signer_info (Pkcs7);
  if (!SignerInfos || (sk_PKCS7_SIGNER_INFO_num (SignerInfos) != 1)) {
    goto _Exit;
  }

  //
  // Locate the TimeStamp CounterSignature.
  //
  SignInfo = sk_PKCS7_SIGNER_INFO_value (SignerInfos, 0);
  if (SignInfo == NULL) {
    goto _Exit;
  }

  //
  // Locate Message Digest which will be the data to be time-stamped.
  //
  EncDigest = SignInfo->enc_digest;
  if (EncDigest == NULL) {
    goto _Exit;
  }

  //
  // The RFC3161 timestamp counterSignature is contained in unauthenticatedAttributes field
  // of SignerInfo.
  //
  Sk = SignInfo->unauth_attr;
  if (Sk == NULL) {
    // No timestamp counterSignature.
    goto _Exit;
  }

  Asn1Type = NULL;
  for (Index = 0; Index < (UINTN)sk_X509_ATTRIBUTE_num (Sk); Index++) {
    //
    // Search valid RFC3161 timestamp counterSignature based on OBJID.
    //
    Xa = sk_X509_ATTRIBUTE_value (Sk, (int)Index);
    if (Xa == NULL) {
      continue;
    }

    XaObj = X509_ATTRIBUTE_get0_object (Xa);
    if (XaObj == NULL) {
      continue;
    }

    if ((OBJ_length (XaObj) != sizeof (mSpcRFC3161OidValue)) ||
        (CompareMem (OBJ_get0_data (XaObj), mSpcRFC3161OidValue, sizeof (mSpcRFC3161OidValue)) != 0))
    {
      continue;
    }

    Asn1Type = X509_ATTRIBUTE_get0_type (Xa, 0);
  }

  if (Asn1Type == NULL) {
    Status = FALSE;
    goto _Exit;
  }

  TSToken   = Asn1Type->value.octet_string->data;
  TokenSize = Asn1Type->value.octet_string->length;

  //
  // TimeStamp counterSignature (Token) verification.
  //
  Status = TimestampTokenVerify (
             TSToken,
             TokenSize,
             TsaCert,
             CertSize,
             EncDigest->data,
             EncDigest->length,
             SigningTime
             );

_Exit:
  //
  // Release Resources
  //
  PKCS7_free (Pkcs7);

  return Status;
}