diff options
Diffstat (limited to 'src/openvpn/cryptoapi.c')
| -rw-r--r-- | src/openvpn/cryptoapi.c | 379 |
1 files changed, 330 insertions, 49 deletions
diff --git a/src/openvpn/cryptoapi.c b/src/openvpn/cryptoapi.c index 720fce0..7f2c3c0 100644 --- a/src/openvpn/cryptoapi.c +++ b/src/openvpn/cryptoapi.c @@ -39,6 +39,7 @@ #ifdef ENABLE_CRYPTOAPI #include <openssl/ssl.h> +#include <openssl/evp.h> #include <openssl/err.h> #include <windows.h> #include <wincrypt.h> @@ -101,6 +102,12 @@ static ERR_STRING_DATA CRYPTOAPI_str_functs[] = { { 0, NULL } }; +/* Global EVP_PKEY_METHOD used to override the sign operation */ +static EVP_PKEY_METHOD *pmethod; +static int (*default_pkey_sign_init) (EVP_PKEY_CTX *ctx); +static int (*default_pkey_sign) (EVP_PKEY_CTX *ctx, unsigned char *sig, + size_t *siglen, const unsigned char *tbs, size_t tbslen); + typedef struct _CAPI_DATA { const CERT_CONTEXT *cert_context; HCRYPTPROV_OR_NCRYPT_KEY_HANDLE crypt_prov; @@ -108,6 +115,80 @@ typedef struct _CAPI_DATA { BOOL free_crypt_prov; } CAPI_DATA; +/** + * Translate OpenSSL padding type to CNG padding type + * Returns 0 for unknown/unsupported padding. + */ +static DWORD +cng_padding_type(int padding) +{ + DWORD pad = 0; + + switch (padding) + { + case RSA_NO_PADDING: + pad = BCRYPT_PAD_NONE; + break; + + case RSA_PKCS1_PADDING: + pad = BCRYPT_PAD_PKCS1; + break; + + case RSA_PKCS1_PSS_PADDING: + pad = BCRYPT_PAD_PSS; + break; + + default: + msg(M_WARN|M_INFO, "cryptoapicert: unknown OpenSSL padding type %d.", + padding); + } + + return pad; +} + +/** + * Translate OpenSSL hash OID to CNG algorithm name. Returns + * "UNKNOWN" for unsupported algorithms and NULL for MD5+SHA1 + * mixed hash used in TLS 1.1 and earlier. + */ +static const wchar_t * +cng_hash_algo(int md_type) +{ + const wchar_t *alg = L"UNKNOWN"; + switch (md_type) + { + case NID_md5: + alg = BCRYPT_MD5_ALGORITHM; + break; + + case NID_sha1: + alg = BCRYPT_SHA1_ALGORITHM; + break; + + case NID_sha256: + alg = BCRYPT_SHA256_ALGORITHM; + break; + + case NID_sha384: + alg = BCRYPT_SHA384_ALGORITHM; + break; + + case NID_sha512: + alg = BCRYPT_SHA512_ALGORITHM; + break; + + case NID_md5_sha1: + case 0: + alg = NULL; + break; + + default: + msg(M_WARN|M_INFO, "cryptoapicert: Unknown hash type NID=0x%x", md_type); + break; + } + return alg; +} + static char * ms_error_text(DWORD ms_err) { @@ -217,25 +298,44 @@ rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, in * Sign the hash in 'from' using NCryptSignHash(). This requires an NCRYPT * key handle in cd->crypt_prov. On return the signature is in 'to'. Returns * the length of the signature or 0 on error. + * Only RSA is supported and padding should be BCRYPT_PAD_PKCS1 or + * BCRYPT_PAD_PSS. * If the hash_algo is not NULL, PKCS #1 DigestInfo header gets added - * to 'from', else it is signed as is. - * For now we support only RSA and the padding is assumed to be PKCS1 v1.5 + * to |from|, else it is signed as is. Use NULL for MD5 + SHA1 hash used + * in TLS 1.1 and earlier. + * In case of PSS padding, |saltlen| should specify the size of salt to use. + * If |to| is NULL returns the required buffer size. */ static int priv_enc_CNG(const CAPI_DATA *cd, const wchar_t *hash_algo, const unsigned char *from, - int flen, unsigned char *to, int tlen, int padding) + int flen, unsigned char *to, int tlen, DWORD padding, DWORD saltlen) { NCRYPT_KEY_HANDLE hkey = cd->crypt_prov; DWORD len = 0; ASSERT(cd->key_spec == CERT_NCRYPT_KEY_SPEC); - msg(D_LOW, "Signing hash using CNG: data size = %d", flen); - - BCRYPT_PKCS1_PADDING_INFO padinfo = {hash_algo}; DWORD status; - status = NCryptSignHash(hkey, padding? &padinfo : NULL, (BYTE*) from, flen, - to, tlen, &len, padding? BCRYPT_PAD_PKCS1 : 0); + msg(D_LOW, "Signing hash using CNG: data size = %d padding = %lu", flen, padding); + + if (padding == BCRYPT_PAD_PKCS1) + { + BCRYPT_PKCS1_PADDING_INFO padinfo = {hash_algo}; + status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen, + to, tlen, &len, padding); + } + else if (padding == BCRYPT_PAD_PSS) + { + BCRYPT_PSS_PADDING_INFO padinfo = {hash_algo, saltlen}; + status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen, + to, tlen, &len, padding); + } + else + { + RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE); + return 0; + } + if (status != ERROR_SUCCESS) { SetLastError(status); @@ -261,16 +361,19 @@ rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, i RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER); return 0; } + + if (cd->key_spec == CERT_NCRYPT_KEY_SPEC) + { + return priv_enc_CNG(cd, NULL, from, flen, to, RSA_size(rsa), + cng_padding_type(padding), 0); + } + if (padding != RSA_PKCS1_PADDING) { /* AFAICS, CryptSignHash() *always* uses PKCS1 padding. */ RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE); return 0; } - if (cd->key_spec == CERT_NCRYPT_KEY_SPEC) - { - return priv_enc_CNG(cd, NULL, from, flen, to, RSA_size(rsa), padding); - } /* Unfortunately, there is no "CryptSign()" function in CryptoAPI, that would * be way to straightforward for M$, I guess... So we have to do it this @@ -333,12 +436,13 @@ rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, i return len; } -/* +/** * Sign the hash in |m| and return the signature in |sig|. * Returns 1 on success, 0 on error. * NCryptSignHash() is used to sign and it is instructed to add the * the PKCS #1 DigestInfo header to |m| unless the hash algorithm is * the MD5/SHA1 combination used in TLS 1.1 and earlier versions. + * OpenSSL exercises this callback only when padding is PKCS1 v1.5. */ static int rsa_sign_CNG(int type, const unsigned char *m, unsigned int m_len, @@ -355,45 +459,17 @@ rsa_sign_CNG(int type, const unsigned char *m, unsigned int m_len, return 0; } - switch (type) + alg = cng_hash_algo(type); + if (alg && wcscmp(alg, L"UNKNOWN") == 0) { - case NID_md5: - alg = BCRYPT_MD5_ALGORITHM; - break; - - case NID_sha1: - alg = BCRYPT_SHA1_ALGORITHM; - break; - - case NID_sha256: - alg = BCRYPT_SHA256_ALGORITHM; - break; - - case NID_sha384: - alg = BCRYPT_SHA384_ALGORITHM; - break; - - case NID_sha512: - alg = BCRYPT_SHA512_ALGORITHM; - break; - - case NID_md5_sha1: - if (m_len != SSL_SIG_LENGTH) - { - RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH); - return 0; - } - /* No DigestInfo header is required -- set alg-name to NULL */ - alg = NULL; - break; - default: - msg(M_WARN, "cryptoapicert: Unknown hash type NID=0x%x", type); - RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE); - return 0; + RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE); + return 0; } - *siglen = priv_enc_CNG(cd, alg, m, (int)m_len, sig, RSA_size(rsa), padding); - return (siglen == 0) ? 0 : 1; + *siglen = priv_enc_CNG(cd, alg, m, (int)m_len, sig, RSA_size(rsa), + cng_padding_type(padding), 0); + + return (*siglen == 0) ? 0 : 1; } /* decrypt */ @@ -518,6 +594,176 @@ find_certificate_in_store(const char *cert_prop, HCERTSTORE cert_store) return rv; } +#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) + +static const CAPI_DATA * +retrieve_capi_data(EVP_PKEY *pkey) +{ + const CAPI_DATA *cd = NULL; + + if (pkey && EVP_PKEY_id(pkey) == EVP_PKEY_RSA) + { + RSA *rsa = EVP_PKEY_get0_RSA(pkey); + if (rsa) + { + cd = (CAPI_DATA *)RSA_meth_get0_app_data(RSA_get_method(rsa)); + } + } + return cd; +} + +static int +pkey_rsa_sign_init(EVP_PKEY_CTX *ctx) +{ + EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx); + + if (pkey && retrieve_capi_data(pkey)) + { + return 1; /* Return success */ + } + else if (default_pkey_sign_init) /* Not our key. Call the default method */ + { + return default_pkey_sign_init(ctx); + } + return 1; +} + +/** + * Implementation of EVP_PKEY_sign() using CNG: sign the digest in |tbs| + * and save the the signature in |sig| and its size in |*siglen|. + * If |sig| is NULL the required buffer size is returned in |*siglen|. + * Returns 1 on success, 0 or a negative integer on error. + */ +static int +pkey_rsa_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen, + const unsigned char *tbs, size_t tbslen) +{ + EVP_PKEY *pkey = NULL; + const CAPI_DATA *cd = NULL; + EVP_MD *md = NULL; + const wchar_t *alg = NULL; + + int padding; + int hashlen; + int saltlen; + + pkey = EVP_PKEY_CTX_get0_pkey(ctx); + if (pkey) + { + cd = retrieve_capi_data(pkey); + } + + /* + * We intercept all sign requests, not just the one's for our key. + * Check the key and call the saved OpenSSL method for unknown keys. + */ + if (!pkey || !cd) + { + if (default_pkey_sign) + { + return default_pkey_sign(ctx, sig, siglen, tbs, tbslen); + } + else /* This should not happen */ + { + msg(M_FATAL, "cryptopaicert: Unknown key and no default sign operation to fallback on"); + return -1; + } + } + + if (!EVP_PKEY_CTX_get_rsa_padding(ctx, &padding)) + { + padding = RSA_PKCS1_PADDING; /* Default padding for RSA */ + } + + if (EVP_PKEY_CTX_get_signature_md(ctx, &md)) + { + hashlen = EVP_MD_size(md); + alg = cng_hash_algo(EVP_MD_type(md)); + + /* + * alg == NULL indicates legacy MD5+SHA1 hash, else alg should be a valid + * digest algorithm. + */ + if (alg && wcscmp(alg, L"UNKNOWN") == 0) + { + RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE); + return -1; + } + } + else + { + msg(M_NONFATAL, "cryptoapicert: could not determine the signature digest algorithm"); + RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE); + return -1; + } + + if (tbslen != (size_t)hashlen) + { + RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_INVALID_DIGEST_LENGTH); + return -1; + } + + /* If padding is PSS, determine parameters to pass to CNG */ + if (padding == RSA_PKCS1_PSS_PADDING) + { + /* + * Ensure the digest type for signature and mask generation match. + * In CNG there is no option to specify separate hash functions for + * the two, but OpenSSL supports it. However, I have not seen the + * two being different in practice. Also the recommended practice is + * to use the same for both (rfc 8017 sec 8.1). + */ + EVP_MD *mgf1md; + if (!EVP_PKEY_CTX_get_rsa_mgf1_md(ctx, &mgf1md) + || EVP_MD_type(mgf1md) != EVP_MD_type(md)) + { + msg(M_NONFATAL, "cryptoapicert: Unknown MGF1 digest type or does" + " not match the signature digest type."); + RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNSUPPORTED_MASK_PARAMETER); + } + + if (!EVP_PKEY_CTX_get_rsa_pss_saltlen(ctx, &saltlen)) + { + msg(M_WARN|M_INFO, "cryptoapicert: unable to get the salt length from context." + " Using the default value."); + saltlen = -1; + } + + /* + * In OpenSSL saltlen = -1 indicates to use the size of the digest as + * size of the salt. A value of -2 or -3 indicates maximum salt length + * that will fit. See RSA_padding_add_PKCS1_PSS_mgf1() of OpenSSL. + */ + if (saltlen == -1) + { + saltlen = hashlen; + } + else if (saltlen < 0) + { + const RSA *rsa = EVP_PKEY_get0_RSA(pkey); + saltlen = RSA_size(rsa) - hashlen - 2; /* max salt length for RSASSA-PSS */ + if (RSA_bits(rsa) &0x7) /* number of bits in the key not a multiple of 8 */ + { + saltlen--; + } + } + + if (saltlen < 0) + { + RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); + return -1; + } + msg(D_LOW, "cryptoapicert: PSS padding using saltlen = %d", saltlen); + } + + *siglen = priv_enc_CNG(cd, alg, tbs, (int)tbslen, sig, *siglen, + cng_padding_type(padding), (DWORD)saltlen); + + return (*siglen == 0) ? 0 : 1; +} + +#endif /* OPENSSL_VERSION >= 1.1.0 */ + int SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop) { @@ -620,10 +866,45 @@ SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop) /* For CNG, set the RSA_sign method which gets priority over priv_enc(). * This method is called with the raw hash without the digestinfo * header and works better when using NCryptSignHash() with some tokens. + * However, if PSS padding is in use, openssl does not call this + * function but adds the padding and then calls rsa_priv_enc() + * with padding set to NONE which is not supported by CNG. + * So, when posisble (OpenSSL 1.1.0 and up), we hook on to the sign + * operation in EVP_PKEY_METHOD struct. */ if (cd->key_spec == CERT_NCRYPT_KEY_SPEC) { +#if (OPENSSL_VERSION_NUMBER < 0x10100000L) RSA_meth_set_sign(my_rsa_method, rsa_sign_CNG); +#else + /* pmethod is global -- initialize only if NULL */ + if (!pmethod) + { + pmethod = EVP_PKEY_meth_new(EVP_PKEY_RSA, 0); + if (!pmethod) + { + SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE); + goto err; + } + const EVP_PKEY_METHOD *default_pmethod = EVP_PKEY_meth_find(EVP_PKEY_RSA); + EVP_PKEY_meth_copy(pmethod, default_pmethod); + + /* We want to override only sign_init() and sign() */ + EVP_PKEY_meth_set_sign(pmethod, pkey_rsa_sign_init, pkey_rsa_sign); + EVP_PKEY_meth_add0(pmethod); + + /* Keep a copy of the default sign and sign_init methods */ + +#if (OPENSSL_VERSION_NUMBER < 0x1010009fL) /* < version 1.1.0i */ + /* The function signature is not const-correct in these versions */ + EVP_PKEY_meth_get_sign((EVP_PKEY_METHOD *)default_pmethod, &default_pkey_sign_init, + &default_pkey_sign); +#else + EVP_PKEY_meth_get_sign(default_pmethod, &default_pkey_sign_init, + &default_pkey_sign); +#endif + } +#endif /* (OPENSSL_VERSION_NUMBER < 0x10100000L) */ } rsa = RSA_new(); |