privatekey.c

 
#include <freerdp/config.h>
 
#include <errno.h>
#include <stdio.h>
#include <string.h>
 
#include <winpr/assert.h>
#include <winpr/wtypes.h>
#include <winpr/crt.h>
#include <winpr/file.h>
#include <winpr/crypto.h>
 
#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <openssl/bn.h>
#include <openssl/err.h>
 
#include "privatekey.h"
#include "cert_common.h"
 
#include <freerdp/crypto/privatekey.h>
 
#include <openssl/evp.h>
 
#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
#include <openssl/core_names.h>
#endif
 
#include "x509_utils.h"
#include "crypto.h"
#include "opensslcompat.h"
 
#define TAG FREERDP_TAG("crypto")
 
struct rdp_private_key
{
  EVP_PKEY* evp;
 
  rdpCertInfo cert;
  BYTE* PrivateExponent;
  DWORD PrivateExponentLength;
};
 
/*
 * Terminal Services Signing Keys.
 * Yes, Terminal Services Private Key is publicly available.
 */
 
static BYTE tssk_modulus[] = { 0x3d, 0x3a, 0x5e, 0xbd, 0x72, 0x43, 0x3e, 0xc9, 0x4d, 0xbb, 0xc1,
                             0x1e, 0x4a, 0xba, 0x5f, 0xcb, 0x3e, 0x88, 0x20, 0x87, 0xef, 0xf5,
                             0xc1, 0xe2, 0xd7, 0xb7, 0x6b, 0x9a, 0xf2, 0x52, 0x45, 0x95, 0xce,
                             0x63, 0x65, 0x6b, 0x58, 0x3a, 0xfe, 0xef, 0x7c, 0xe7, 0xbf, 0xfe,
                             0x3d, 0xf6, 0x5c, 0x7d, 0x6c, 0x5e, 0x06, 0x09, 0x1a, 0xf5, 0x61,
                             0xbb, 0x20, 0x93, 0x09, 0x5f, 0x05, 0x6d, 0xea, 0x87 };
 
static BYTE tssk_privateExponent[] = {
  0x87, 0xa7, 0x19, 0x32, 0xda, 0x11, 0x87, 0x55, 0x58, 0x00, 0x16, 0x16, 0x25, 0x65, 0x68, 0xf8,
  0x24, 0x3e, 0xe6, 0xfa, 0xe9, 0x67, 0x49, 0x94, 0xcf, 0x92, 0xcc, 0x33, 0x99, 0xe8, 0x08, 0x60,
  0x17, 0x9a, 0x12, 0x9f, 0x24, 0xdd, 0xb1, 0x24, 0x99, 0xc7, 0x3a, 0xb8, 0x0a, 0x7b, 0x0d, 0xdd,
  0x35, 0x07, 0x79, 0x17, 0x0b, 0x51, 0x9b, 0xb3, 0xc7, 0x10, 0x01, 0x13, 0xe7, 0x3f, 0xf3, 0x5f
};
 
static const rdpPrivateKey tssk = { .PrivateExponent = tssk_privateExponent,
                                  .PrivateExponentLength = sizeof(tssk_privateExponent),
                                  .cert = { .Modulus = tssk_modulus,
                                            .ModulusLength = sizeof(tssk_modulus) } };
const rdpPrivateKey* priv_key_tssk = &tssk;
 
#if !defined(OPENSSL_VERSION_MAJOR) || (OPENSSL_VERSION_MAJOR < 3)
static RSA* evp_pkey_to_rsa(const rdpPrivateKey* key)
{
  if (!freerdp_key_is_rsa(key))
  {
    WLog_WARN(TAG, "Key is no RSA key");
    return NULL;
  }
 
  RSA* rsa = NULL;
  BIO* bio = BIO_new(
#if defined(LIBRESSL_VERSION_NUMBER)
      BIO_s_mem()
#else
      BIO_s_secmem()
#endif
  );
  if (!bio)
    return NULL;
  const int rc = PEM_write_bio_PrivateKey(bio, key->evp, NULL, NULL, 0, NULL, NULL);
  if (rc != 1)
    goto fail;
  rsa = PEM_read_bio_RSAPrivateKey(bio, NULL, NULL, NULL);
fail:
  BIO_free_all(bio);
  return rsa;
}
#endif
 
static EVP_PKEY* evp_pkey_utils_from_pem(const char* data, size_t len, BOOL fromFile,
                                         const char* password)
{
  EVP_PKEY* evp = NULL;
  BIO* bio = NULL;
  if (fromFile)
    bio = BIO_new_file(data, "rb");
  else
  {
    if (len > INT_MAX)
      return NULL;
    bio = BIO_new_mem_buf(data, (int)len);
  }
 
  if (!bio)
  {
    WLog_ERR(TAG, "BIO_new failed for private key");
    return NULL;
  }
 
  evp = PEM_read_bio_PrivateKey(bio, NULL, NULL, WINPR_CAST_CONST_PTR_AWAY(password, void*));
  BIO_free_all(bio);
  if (!evp)
    WLog_ERR(TAG, "PEM_read_bio_PrivateKey returned NULL [input length %" PRIuz "]", len);
 
  return evp;
}
 
static BOOL key_read_private(rdpPrivateKey* key)
{
  BOOL rc = FALSE;
 
  WINPR_ASSERT(key);
  WINPR_ASSERT(key->evp);
 
  /* The key is not an RSA key, that means we just return success. */
  if (!freerdp_key_is_rsa(key))
    return TRUE;
 
#if !defined(OPENSSL_VERSION_MAJOR) || (OPENSSL_VERSION_MAJOR < 3)
  RSA* rsa = evp_pkey_to_rsa(key);
  if (!rsa)
  {
    char ebuffer[256] = { 0 };
    WLog_ERR(TAG, "unable to load RSA key: %s.",
             winpr_strerror(errno, ebuffer, sizeof(ebuffer)));
    goto fail;
  }
 
  switch (RSA_check_key(rsa))
  {
    case 0:
      WLog_ERR(TAG, "invalid RSA key");
      goto fail;
 
    case 1:
      /* Valid key. */
      break;
 
    default:
    {
      char ebuffer[256] = { 0 };
      WLog_ERR(TAG, "unexpected error when checking RSA key: %s.",
               winpr_strerror(errno, ebuffer, sizeof(ebuffer)));
      goto fail;
    }
  }
 
  const BIGNUM* rsa_e = NULL;
  const BIGNUM* rsa_n = NULL;
  const BIGNUM* rsa_d = NULL;
 
  RSA_get0_key(rsa, &rsa_n, &rsa_e, &rsa_d);
#else
  BIGNUM* rsa_e = NULL;
  BIGNUM* rsa_n = NULL;
  BIGNUM* rsa_d = NULL;
 
  if (!EVP_PKEY_get_bn_param(key->evp, OSSL_PKEY_PARAM_RSA_N, &rsa_n))
    goto fail;
  if (!EVP_PKEY_get_bn_param(key->evp, OSSL_PKEY_PARAM_RSA_E, &rsa_e))
    goto fail;
  if (!EVP_PKEY_get_bn_param(key->evp, OSSL_PKEY_PARAM_RSA_D, &rsa_d))
    goto fail;
#endif
  if (BN_num_bytes(rsa_e) > 4)
  {
    WLog_ERR(TAG, "RSA public exponent too large");
    goto fail;
  }
 
  if (!read_bignum(&key->PrivateExponent, &key->PrivateExponentLength, rsa_d, TRUE))
    goto fail;
 
  if (!cert_info_create(&key->cert, rsa_n, rsa_e))
    goto fail;
  rc = TRUE;
fail:
#if !defined(OPENSSL_VERSION_MAJOR) || (OPENSSL_VERSION_MAJOR < 3)
  RSA_free(rsa);
#else
  BN_free(rsa_d);
  BN_free(rsa_e);
  BN_free(rsa_n);
#endif
  return rc;
}
 
rdpPrivateKey* freerdp_key_new_from_pem(const char* pem)
{
  return freerdp_key_new_from_pem_enc(pem, NULL);
}
 
rdpPrivateKey* freerdp_key_new_from_pem_enc(const char* pem, const char* password)
{
  rdpPrivateKey* key = freerdp_key_new();
  if (!key || !pem)
    goto fail;
  key->evp = evp_pkey_utils_from_pem(pem, strlen(pem), FALSE, password);
  if (!key->evp)
    goto fail;
  if (!key_read_private(key))
    goto fail;
  return key;
fail:
  freerdp_key_free(key);
  return NULL;
}
 
rdpPrivateKey* freerdp_key_new_from_file(const char* keyfile)
{
  return freerdp_key_new_from_file_enc(keyfile, NULL);
}
 
rdpPrivateKey* freerdp_key_new_from_file_enc(const char* keyfile, const char* password)
{
  rdpPrivateKey* key = freerdp_key_new();
  if (!key || !keyfile)
    goto fail;
 
  key->evp = evp_pkey_utils_from_pem(keyfile, strlen(keyfile), TRUE, password);
  if (!key->evp)
    goto fail;
  if (!key_read_private(key))
    goto fail;
  return key;
fail:
  freerdp_key_free(key);
  return NULL;
}
 
rdpPrivateKey* freerdp_key_new(void)
{
  return calloc(1, sizeof(rdpPrivateKey));
}
 
rdpPrivateKey* freerdp_key_clone(const rdpPrivateKey* key)
{
  if (!key)
    return NULL;
 
  rdpPrivateKey* _key = (rdpPrivateKey*)calloc(1, sizeof(rdpPrivateKey));
 
  if (!_key)
    return NULL;
 
  if (key->evp)
  {
    _key->evp = key->evp;
    if (!_key->evp)
      goto out_fail;
    EVP_PKEY_up_ref(_key->evp);
  }
 
  if (key->PrivateExponent)
  {
    _key->PrivateExponent = (BYTE*)malloc(key->PrivateExponentLength);
 
    if (!_key->PrivateExponent)
      goto out_fail;
 
    CopyMemory(_key->PrivateExponent, key->PrivateExponent, key->PrivateExponentLength);
    _key->PrivateExponentLength = key->PrivateExponentLength;
  }
 
  if (!cert_info_clone(&_key->cert, &key->cert))
    goto out_fail;
 
  return _key;
out_fail:
  WINPR_PRAGMA_DIAG_PUSH
  WINPR_PRAGMA_DIAG_IGNORED_MISMATCHED_DEALLOC
  freerdp_key_free(_key);
  WINPR_PRAGMA_DIAG_POP
  return NULL;
}
 
void freerdp_key_free(rdpPrivateKey* key)
{
  if (!key)
    return;
 
  EVP_PKEY_free(key->evp);
  if (key->PrivateExponent)
    memset(key->PrivateExponent, 0, key->PrivateExponentLength);
  free(key->PrivateExponent);
  cert_info_free(&key->cert);
  free(key);
}
 
const rdpCertInfo* freerdp_key_get_info(const rdpPrivateKey* key)
{
  WINPR_ASSERT(key);
  if (!freerdp_key_is_rsa(key))
    return NULL;
  return &key->cert;
}
 
const BYTE* freerdp_key_get_exponent(const rdpPrivateKey* key, size_t* plength)
{
  WINPR_ASSERT(key);
  if (!freerdp_key_is_rsa(key))
  {
    if (plength)
      *plength = 0;
    return NULL;
  }
 
  if (plength)
    *plength = key->PrivateExponentLength;
  return key->PrivateExponent;
}
 
EVP_PKEY* freerdp_key_get_evp_pkey(const rdpPrivateKey* key)
{
  WINPR_ASSERT(key);
 
  EVP_PKEY* evp = key->evp;
  WINPR_ASSERT(evp);
  EVP_PKEY_up_ref(evp);
  return evp;
}
 
BOOL freerdp_key_is_rsa(const rdpPrivateKey* key)
{
  WINPR_ASSERT(key);
  if (key == priv_key_tssk)
    return TRUE;
 
  WINPR_ASSERT(key->evp);
  return (EVP_PKEY_id(key->evp) == EVP_PKEY_RSA);
}
 
size_t freerdp_key_get_bits(const rdpPrivateKey* key)
{
  int rc = -1;
#if !defined(OPENSSL_VERSION_MAJOR) || (OPENSSL_VERSION_MAJOR < 3)
  RSA* rsa = evp_pkey_to_rsa(key);
  if (rsa)
  {
    rc = RSA_bits(rsa);
    RSA_free(rsa);
  }
#else
  rc = EVP_PKEY_get_bits(key->evp);
#endif
 
  return WINPR_ASSERTING_INT_CAST(size_t, rc);
}
 
BOOL freerdp_key_generate(rdpPrivateKey* key, const char* type, size_t count, ...)
{
  BOOL rc = FALSE;
 
  if (!type)
  {
    WLog_ERR(TAG, "Invalid argument type=%s", type);
    return FALSE;
  }
  if (strncmp("RSA", type, 4) != 0)
  {
    WLog_ERR(TAG, "Argument type=%s is currently not supported, aborting", type);
    return FALSE;
  }
  if (count != 1)
  {
    WLog_ERR(TAG, "Argument type=%s requires count=1, got %" PRIuz ", aborting", type, count);
    return FALSE;
  }
  va_list ap;
  va_start(ap, count);
  const int key_length = va_arg(ap, int);
  va_end(ap);
 
#if !defined(OPENSSL_VERSION_MAJOR) || (OPENSSL_VERSION_MAJOR < 3)
  RSA* rsa = NULL;
#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
  rsa = RSA_generate_key(key_length, RSA_F4, NULL, NULL);
#else
  {
    BIGNUM* bn = BN_secure_new();
 
    if (!bn)
      return FALSE;
 
    rsa = RSA_new();
 
    if (!rsa)
    {
      BN_clear_free(bn);
      return FALSE;
    }
 
    BN_set_word(bn, RSA_F4);
    const int res = RSA_generate_key_ex(rsa, key_length, bn, NULL);
    BN_clear_free(bn);
 
    if (res != 1)
      return FALSE;
  }
#endif
 
  EVP_PKEY_free(key->evp);
  key->evp = EVP_PKEY_new();
 
  if (!EVP_PKEY_assign_RSA(key->evp, rsa))
  {
    EVP_PKEY_free(key->evp);
    key->evp = NULL;
    RSA_free(rsa);
    return FALSE;
  }
 
  rc = TRUE;
#else
  EVP_PKEY_CTX* pctx = EVP_PKEY_CTX_new_from_name(NULL, type, NULL);
  if (!pctx)
    return FALSE;
 
  if (EVP_PKEY_keygen_init(pctx) != 1)
    goto fail;
 
  if (EVP_PKEY_CTX_set_rsa_keygen_bits(pctx, key_length) != 1)
    goto fail;
 
  EVP_PKEY_free(key->evp);
  key->evp = NULL;
 
  if (EVP_PKEY_generate(pctx, &key->evp) != 1)
    goto fail;
 
  rc = TRUE;
fail:
  EVP_PKEY_CTX_free(pctx);
#endif
  return rc;
}
 
BYTE* freerdp_key_get_param(const rdpPrivateKey* key, enum FREERDP_KEY_PARAM param, size_t* plength)
{
  BYTE* buf = NULL;
 
  WINPR_ASSERT(key);
  WINPR_ASSERT(plength);
 
  *plength = 0;
 
  BIGNUM* bn = NULL;
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
 
  const char* pk = NULL;
  switch (param)
  {
    case FREERDP_KEY_PARAM_RSA_D:
      pk = OSSL_PKEY_PARAM_RSA_D;
      break;
    case FREERDP_KEY_PARAM_RSA_E:
      pk = OSSL_PKEY_PARAM_RSA_E;
      break;
    case FREERDP_KEY_PARAM_RSA_N:
      pk = OSSL_PKEY_PARAM_RSA_N;
      break;
    default:
      return NULL;
  }
 
  if (!EVP_PKEY_get_bn_param(key->evp, pk, &bn))
    return NULL;
#else
  {
    const RSA* rsa = EVP_PKEY_get0_RSA(key->evp);
    if (!rsa)
      return NULL;
 
    const BIGNUM* cbn = NULL;
    switch (param)
    {
      case FREERDP_KEY_PARAM_RSA_D:
#if OPENSSL_VERSION_NUMBER >= 0x10101007L
        cbn = RSA_get0_d(rsa);
#endif
        break;
      case FREERDP_KEY_PARAM_RSA_E:
#if OPENSSL_VERSION_NUMBER >= 0x10101007L
        cbn = RSA_get0_e(rsa);
#endif
        break;
      case FREERDP_KEY_PARAM_RSA_N:
#if OPENSSL_VERSION_NUMBER >= 0x10101007L
        cbn = RSA_get0_n(rsa);
#endif
        break;
      default:
        return NULL;
    }
    if (!cbn)
      return NULL;
    bn = BN_dup(cbn);
    if (!bn)
      return NULL;
  }
#endif
 
  const int length = BN_num_bytes(bn);
  if (length < 0)
    goto fail;
 
  const size_t alloc_size = (size_t)length + 1ull;
  buf = calloc(alloc_size, sizeof(BYTE));
  if (!buf)
    goto fail;
 
  const int bnlen = BN_bn2bin(bn, buf);
  if (bnlen != length)
  {
    free(buf);
    buf = NULL;
  }
  else
    *plength = WINPR_ASSERTING_INT_CAST(size_t, length);
 
fail:
  BN_free(bn);
  return buf;
}
 
WINPR_DIGEST_CTX* freerdp_key_digest_sign(rdpPrivateKey* key, WINPR_MD_TYPE digest)
{
  WINPR_DIGEST_CTX* md_ctx = winpr_Digest_New();
  if (!md_ctx)
    return NULL;
 
  if (!winpr_DigestSign_Init(md_ctx, digest, key->evp))
  {
    winpr_Digest_Free(md_ctx);
    return NULL;
  }
  return md_ctx;
}
 
static BOOL bio_read_pem(BIO* bio, char** ppem, size_t* plength)
{
  BOOL rc = FALSE;
 
  WINPR_ASSERT(bio);
  WINPR_ASSERT(ppem);
 
  const size_t blocksize = 2048;
  size_t offset = 0;
  size_t length = blocksize;
  char* pem = NULL;
 
  *ppem = NULL;
  if (plength)
    *plength = 0;
 
  while (offset < length)
  {
    char* tmp = realloc(pem, length + 1);
    if (!tmp)
      goto fail;
    pem = tmp;
 
    ERR_clear_error();
 
    const int status = BIO_read(bio, &pem[offset], (int)(length - offset));
    if (status < 0)
    {
      WLog_ERR(TAG, "failed to read certificate");
      goto fail;
    }
 
    if (status == 0)
      break;
 
    offset += (size_t)status;
    if (length - offset > 0)
      break;
    length += blocksize;
  }
 
  if (pem)
  {
    if (offset >= length)
      goto fail;
    pem[offset] = '\0';
  }
  *ppem = pem;
  if (plength)
    *plength = offset;
  rc = TRUE;
fail:
  if (!rc)
    free(pem);
 
  return rc;
}
 
char* freerdp_key_get_pem(const rdpPrivateKey* key, size_t* plen, const char* password)
{
  WINPR_ASSERT(key);
 
  if (!key->evp)
    return NULL;
 
  BIO* bio = BIO_new(BIO_s_mem());
 
  if (!bio)
  {
    WLog_ERR(TAG, "BIO_new() failure");
    return NULL;
  }
 
  char* pem = NULL;
 
  const EVP_CIPHER* enc = NULL;
  if (password)
    enc = EVP_aes_256_xts();
 
  const int status = PEM_write_bio_PrivateKey(bio, key->evp, enc, NULL, 0, 0,
                                              WINPR_CAST_CONST_PTR_AWAY(password, void*));
  if (status < 0)
  {
    WLog_ERR(TAG, "PEM_write_bio_PrivateKey failure: %d", status);
    goto fail;
  }
 
  (void)bio_read_pem(bio, &pem, plen);
 
fail:
  BIO_free_all(bio);
  return pem;
}