diff options
Diffstat (limited to 'src/openvpn/crypto_openssl.c')
| -rw-r--r-- | src/openvpn/crypto_openssl.c | 282 |
1 files changed, 189 insertions, 93 deletions
diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c index c147245..1ea06bb 100644 --- a/src/openvpn/crypto_openssl.c +++ b/src/openvpn/crypto_openssl.c @@ -42,9 +42,12 @@ #include "integer.h" #include "crypto.h" #include "crypto_backend.h" -#include <openssl/objects.h> -#include <openssl/evp.h> + #include <openssl/des.h> +#include <openssl/err.h> +#include <openssl/evp.h> +#include <openssl/objects.h> +#include <openssl/ssl.h> /* * Check for key size creepage. @@ -58,41 +61,6 @@ #warning Some OpenSSL HMAC message digests now support key lengths greater than MAX_HMAC_KEY_LENGTH -- consider increasing MAX_HMAC_KEY_LENGTH #endif -/* - * - * Workarounds for incompatibilites between OpenSSL libraries. - * Right now we accept OpenSSL libraries from 0.9.5 to 0.9.7. - * - */ - -#if SSLEAY_VERSION_NUMBER < 0x00907000L - -/* Workaround: EVP_CIPHER_mode is defined wrong in OpenSSL 0.9.6 but is fixed in 0.9.7 */ -#undef EVP_CIPHER_mode -#define EVP_CIPHER_mode(e) (((e)->flags) & EVP_CIPH_MODE) - -#define DES_cblock des_cblock -#define DES_is_weak_key des_is_weak_key -#define DES_check_key_parity des_check_key_parity -#define DES_set_odd_parity des_set_odd_parity - -#define HMAC_CTX_init(ctx) CLEAR (*ctx) -#define HMAC_Init_ex(ctx,sec,len,md,impl) HMAC_Init(ctx, sec, len, md) -#define HMAC_CTX_cleanup(ctx) HMAC_cleanup(ctx) -#define EVP_MD_CTX_cleanup(md) CLEAR (*md) - -#define INFO_CALLBACK_SSL_CONST - -#endif - -#ifndef EVP_CIPHER_name -#define EVP_CIPHER_name(e) OBJ_nid2sn(EVP_CIPHER_nid(e)) -#endif - -#ifndef EVP_MD_name -#define EVP_MD_name(e) OBJ_nid2sn(EVP_MD_type(e)) -#endif - #if HAVE_OPENSSL_ENGINE #include <openssl/engine.h> @@ -179,14 +147,6 @@ crypto_init_lib_engine (const char *engine_name) void crypto_init_lib (void) { -#ifndef ENABLE_SSL - /* If SSL is enabled init is taken care of in ssl_openssl.c */ -#ifndef ENABLE_SMALL - ERR_load_crypto_strings (); -#endif - OpenSSL_add_all_algorithms (); -#endif - /* * If you build the OpenSSL library and OpenVPN with * CRYPTO_MDEBUG, you will get a listing of OpenSSL @@ -201,14 +161,6 @@ crypto_init_lib (void) void crypto_uninit_lib (void) { -#ifndef ENABLE_SSL - /* If SSL is enabled cleanup is taken care of in ssl_openssl.c */ - EVP_cleanup (); -#ifndef ENABLE_SMALL - ERR_free_strings (); -#endif -#endif - #ifdef CRYPTO_MDEBUG FILE* fp = fopen ("sdlog", "w"); ASSERT (fp); @@ -237,9 +189,21 @@ crypto_print_openssl_errors(const unsigned int flags) { size_t err = 0; while ((err = ERR_get_error ())) - msg (flags, "OpenSSL: %s", ERR_error_string (err, NULL)); + { + /* Be more clear about frequently occurring "no shared cipher" error */ + if (err == ERR_PACK(ERR_LIB_SSL,SSL_F_SSL3_GET_CLIENT_HELLO, + SSL_R_NO_SHARED_CIPHER)) + { + msg (D_CRYPT_ERRORS, "TLS error: The server has no TLS ciphersuites " + "in common with the client. Your --tls-cipher setting might be " + "too restrictive."); + } + + msg (flags, "OpenSSL: %s", ERR_error_string (err, NULL)); + } } + /* * * OpenSSL memory debugging. If dmalloc debugging is enabled, tell @@ -276,55 +240,97 @@ crypto_init_dmalloc (void) } #endif /* DMALLOC */ -const char * -translate_cipher_name_from_openvpn (const char *cipher_name) { - // OpenSSL doesn't require any translation - return cipher_name; +const cipher_name_pair cipher_name_translation_table[] = { + { "AES-128-GCM", "id-aes128-GCM" }, + { "AES-192-GCM", "id-aes192-GCM" }, + { "AES-256-GCM", "id-aes256-GCM" }, +}; +const size_t cipher_name_translation_table_count = + sizeof (cipher_name_translation_table) / sizeof (*cipher_name_translation_table); + + +static int +cipher_name_cmp(const void *a, const void *b) +{ + const EVP_CIPHER * const *cipher_a = a; + const EVP_CIPHER * const *cipher_b = b; + + const char *cipher_name_a = + translate_cipher_name_to_openvpn(EVP_CIPHER_name(*cipher_a)); + const char *cipher_name_b = + translate_cipher_name_to_openvpn(EVP_CIPHER_name(*cipher_b)); + + return strcmp(cipher_name_a, cipher_name_b); } -const char * -translate_cipher_name_to_openvpn (const char *cipher_name) { - // OpenSSL doesn't require any translation - return cipher_name; +static void +print_cipher(const EVP_CIPHER *cipher) +{ + const char *var_key_size = + (EVP_CIPHER_flags (cipher) & EVP_CIPH_VARIABLE_LENGTH) ? + " by default" : ""; + const char *ssl_only = cipher_kt_mode_cbc(cipher) ? + "" : ", TLS client/server mode only"; + + printf ("%s (%d bit key%s, %d bit block%s)\n", + translate_cipher_name_to_openvpn (EVP_CIPHER_name (cipher)), + EVP_CIPHER_key_length (cipher) * 8, var_key_size, + cipher_kt_block_size (cipher) * 8, ssl_only); } void show_available_ciphers () { int nid; + size_t i; + /* If we ever exceed this, we must be more selective */ + const size_t cipher_list_len = 1000; + const EVP_CIPHER *cipher_list[cipher_list_len]; + size_t num_ciphers = 0; #ifndef ENABLE_SMALL - printf ("The following ciphers and cipher modes are available\n" - "for use with " PACKAGE_NAME ". Each cipher shown below may be\n" - "used as a parameter to the --cipher option. The default\n" - "key size is shown as well as whether or not it can be\n" - "changed with the --keysize directive. Using a CBC mode\n" - "is recommended. In static key mode only CBC mode is allowed.\n\n"); + printf ("The following ciphers and cipher modes are available for use\n" + "with " PACKAGE_NAME ". Each cipher shown below may be use as a\n" + "parameter to the --cipher option. The default key size is\n" + "shown as well as whether or not it can be changed with the\n" + "--keysize directive. Using a CBC or GCM mode is recommended.\n" + "In static key mode only CBC mode is allowed.\n\n"); #endif - for (nid = 0; nid < 10000; ++nid) /* is there a better way to get the size of the nid list? */ + for (nid = 0; nid < 10000; ++nid) { - const EVP_CIPHER *cipher = EVP_get_cipherbynid (nid); - if (cipher) - { - if (cipher_kt_mode_cbc(cipher) + const EVP_CIPHER *cipher = EVP_get_cipherbynid(nid); + if (cipher && (cipher_kt_mode_cbc(cipher) #ifdef ENABLE_OFB_CFB_MODE || cipher_kt_mode_ofb_cfb(cipher) #endif - ) - { - const char *var_key_size = - (EVP_CIPHER_flags (cipher) & EVP_CIPH_VARIABLE_LENGTH) ? - "variable" : "fixed"; - const char *ssl_only = cipher_kt_mode_ofb_cfb(cipher) ? - " (TLS client/server mode)" : ""; - - printf ("%s %d bit default key (%s)%s\n", OBJ_nid2sn (nid), - EVP_CIPHER_key_length (cipher) * 8, var_key_size, - ssl_only); - } +#ifdef HAVE_AEAD_CIPHER_MODES + || cipher_kt_mode_aead(cipher) +#endif + )) + { + cipher_list[num_ciphers++] = cipher; + } + if (num_ciphers == cipher_list_len) + { + msg (M_WARN, "WARNING: Too many ciphers, not showing all"); + break; } } + + qsort (cipher_list, num_ciphers, sizeof(*cipher_list), cipher_name_cmp); + + for (i = 0; i < num_ciphers; i++) { + if (cipher_kt_block_size(cipher_list[i]) >= 128/8) + print_cipher(cipher_list[i]); + } + + printf ("\nThe following ciphers have a block size of less than 128 bits, \n" + "and are therefore deprecated. Do not use unless you have to.\n\n"); + for (i = 0; i < num_ciphers; i++) { + if (cipher_kt_block_size(cipher_list[i]) < 128/8) + print_cipher(cipher_list[i]); + } printf ("\n"); } @@ -498,13 +504,20 @@ cipher_kt_get (const char *ciphername) cipher = EVP_get_cipherbyname (ciphername); if (NULL == cipher) - crypto_msg (M_FATAL, "Cipher algorithm '%s' not found", ciphername); + { + crypto_msg (D_LOW, "Cipher algorithm '%s' not found", ciphername); + return NULL; + } + if (EVP_CIPHER_key_length (cipher) > MAX_CIPHER_KEY_LENGTH) - msg (M_FATAL, "Cipher algorithm '%s' uses a default key size (%d bytes) which is larger than " PACKAGE_NAME "'s current maximum key size (%d bytes)", - ciphername, - EVP_CIPHER_key_length (cipher), - MAX_CIPHER_KEY_LENGTH); + { + msg (D_LOW, "Cipher algorithm '%s' uses a default key size (%d bytes) " + "which is larger than " PACKAGE_NAME "'s current maximum key size " + "(%d bytes)", ciphername, EVP_CIPHER_key_length (cipher), + MAX_CIPHER_KEY_LENGTH); + return NULL; + } return cipher; } @@ -530,9 +543,46 @@ cipher_kt_iv_size (const EVP_CIPHER *cipher_kt) } int -cipher_kt_block_size (const EVP_CIPHER *cipher_kt) +cipher_kt_block_size (const EVP_CIPHER *cipher) { + /* OpenSSL reports OFB/CFB/GCM cipher block sizes as '1 byte'. To work + * around that, try to replace the mode with 'CBC' and return the block size + * reported for that cipher, if possible. If that doesn't work, just return + * the value reported by OpenSSL. + */ + char *name = NULL; + char *mode_str = NULL; + const char *orig_name = NULL; + const EVP_CIPHER *cbc_cipher = NULL; + + int block_size = EVP_CIPHER_block_size(cipher); + + orig_name = cipher_kt_name(cipher); + if (!orig_name) + goto cleanup; + + name = string_alloc(translate_cipher_name_to_openvpn(orig_name), NULL); + mode_str = strrchr (name, '-'); + if (!mode_str || strlen(mode_str) < 4) + goto cleanup; + + strcpy (mode_str, "-CBC"); + + cbc_cipher = EVP_get_cipherbyname(translate_cipher_name_from_openvpn(name)); + if (cbc_cipher) + block_size = EVP_CIPHER_block_size(cbc_cipher); + +cleanup: + free (name); + return block_size; +} + +int +cipher_kt_tag_size (const EVP_CIPHER *cipher_kt) { - return EVP_CIPHER_block_size (cipher_kt); + if (cipher_kt_mode_aead(cipher_kt)) + return OPENVPN_AEAD_TAG_LENGTH; + else + return 0; } int @@ -565,6 +615,16 @@ cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher) ; } +bool +cipher_kt_mode_aead(const cipher_kt_t *cipher) +{ +#ifdef HAVE_AEAD_CIPHER_MODES + return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_GCM); +#else + return false; +#endif +} + /* * * Generic cipher context functions @@ -606,6 +666,15 @@ cipher_ctx_iv_length (const EVP_CIPHER_CTX *ctx) return EVP_CIPHER_CTX_iv_length (ctx); } +int cipher_ctx_get_tag (EVP_CIPHER_CTX *ctx, uint8_t *tag_buf, int tag_size) +{ +#ifdef HAVE_AEAD_CIPHER_MODES + return EVP_CIPHER_CTX_ctrl (ctx, EVP_CTRL_GCM_GET_TAG, tag_size, tag_buf); +#else + ASSERT (0); +#endif +} + int cipher_ctx_block_size(const EVP_CIPHER_CTX *ctx) { @@ -621,7 +690,7 @@ cipher_ctx_mode (const EVP_CIPHER_CTX *ctx) const cipher_kt_t * cipher_ctx_get_cipher_kt (const cipher_ctx_t *ctx) { - return EVP_CIPHER_CTX_cipher(ctx); + return ctx ? EVP_CIPHER_CTX_cipher(ctx) : NULL; } @@ -632,6 +701,19 @@ cipher_ctx_reset (EVP_CIPHER_CTX *ctx, uint8_t *iv_buf) } int +cipher_ctx_update_ad (EVP_CIPHER_CTX *ctx, const uint8_t *src, int src_len) +{ +#ifdef HAVE_AEAD_CIPHER_MODES + int len; + if (!EVP_CipherUpdate (ctx, NULL, &len, src, src_len)) + crypto_msg(M_FATAL, "%s: EVP_CipherUpdate() failed", __func__); + return 1; +#else + ASSERT (0); +#endif +} + +int cipher_ctx_update (EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len, uint8_t *src, int src_len) { @@ -646,6 +728,20 @@ cipher_ctx_final (EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len) return EVP_CipherFinal (ctx, dst, dst_len); } +int +cipher_ctx_final_check_tag (EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len, + uint8_t *tag, size_t tag_len) +{ +#ifdef HAVE_AEAD_CIPHER_MODES + ASSERT (tag_len < SIZE_MAX); + if (!EVP_CIPHER_CTX_ctrl (ctx, EVP_CTRL_GCM_SET_TAG, tag_len, tag)) + return 0; + + return cipher_ctx_final (ctx, dst, dst_len); +#else + ASSERT (0); +#endif +} void cipher_des_encrypt_ecb (const unsigned char key[DES_KEY_LENGTH], |