diff options
Diffstat (limited to 'openvpn/src/openvpn/crypto.c')
| -rw-r--r-- | openvpn/src/openvpn/crypto.c | 1451 |
1 files changed, 0 insertions, 1451 deletions
diff --git a/openvpn/src/openvpn/crypto.c b/openvpn/src/openvpn/crypto.c deleted file mode 100644 index ac2eecdd..00000000 --- a/openvpn/src/openvpn/crypto.c +++ /dev/null @@ -1,1451 +0,0 @@ -/* - * OpenVPN -- An application to securely tunnel IP networks - * over a single TCP/UDP port, with support for SSL/TLS-based - * session authentication and key exchange, - * packet encryption, packet authentication, and - * packet compression. - * - * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net> - * Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 - * as published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program (see the file COPYING included with this - * distribution); if not, write to the Free Software Foundation, Inc., - * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - -#ifdef HAVE_CONFIG_H -#include "config.h" -#elif defined(_MSC_VER) -#include "config-msvc.h" -#endif - -#include "syshead.h" - -#ifdef ENABLE_CRYPTO - -#include "crypto.h" -#include "error.h" -#include "misc.h" - -#include "memdbg.h" - -/* - * Encryption and Compression Routines. - * - * On entry, buf contains the input data and length. - * On exit, it should be set to the output data and length. - * - * If buf->len is <= 0 we should return - * If buf->len is set to 0 on exit it tells the caller to ignore the packet. - * - * work is a workspace buffer we are given of size BUF_SIZE. - * work may be used to return output data, or the input buffer - * may be modified and returned as output. If output data is - * returned in work, the data should start after FRAME_HEADROOM bytes - * of padding to leave room for downstream routines to prepend. - * - * Up to a total of FRAME_HEADROOM bytes may be prepended to the input buf - * by all routines (encryption, decryption, compression, and decompression). - * - * Note that the buf_prepend return will assert if we try to - * make a header bigger than FRAME_HEADROOM. This should not - * happen unless the frame parameters are wrong. - */ - -#define CRYPT_ERROR(format) \ - do { msg (D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false) - -void -openvpn_encrypt (struct buffer *buf, struct buffer work, - const struct crypto_options *opt, - const struct frame* frame) -{ - struct gc_arena gc; - gc_init (&gc); - - if (buf->len > 0 && opt->key_ctx_bi) - { - struct key_ctx *ctx = &opt->key_ctx_bi->encrypt; - - /* Do Encrypt from buf -> work */ - if (ctx->cipher) - { - uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH]; - const int iv_size = cipher_ctx_iv_length (ctx->cipher); - const unsigned int mode = cipher_ctx_mode (ctx->cipher); - int outlen; - - if (mode == OPENVPN_MODE_CBC) - { - CLEAR (iv_buf); - - /* generate pseudo-random IV */ - if (opt->flags & CO_USE_IV) - prng_bytes (iv_buf, iv_size); - - /* Put packet ID in plaintext buffer or IV, depending on cipher mode */ - if (opt->packet_id) - { - struct packet_id_net pin; - packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)); - ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true)); - } - } - else if (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB) - { - struct packet_id_net pin; - struct buffer b; - - ASSERT (opt->flags & CO_USE_IV); /* IV and packet-ID required */ - ASSERT (opt->packet_id); /* for this mode. */ - - packet_id_alloc_outgoing (&opt->packet_id->send, &pin, true); - memset (iv_buf, 0, iv_size); - buf_set_write (&b, iv_buf, iv_size); - ASSERT (packet_id_write (&pin, &b, true, false)); - } - else /* We only support CBC, CFB, or OFB modes right now */ - { - ASSERT (0); - } - - /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */ - ASSERT (buf_init (&work, FRAME_HEADROOM (frame))); - - /* set the IV pseudo-randomly */ - if (opt->flags & CO_USE_IV) - dmsg (D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc)); - - dmsg (D_PACKET_CONTENT, "ENCRYPT FROM: %s", - format_hex (BPTR (buf), BLEN (buf), 80, &gc)); - - /* cipher_ctx was already initialized with key & keylen */ - ASSERT (cipher_ctx_reset(ctx->cipher, iv_buf)); - - /* Buffer overflow check */ - if (!buf_safe (&work, buf->len + cipher_ctx_block_size(ctx->cipher))) - { - msg (D_CRYPT_ERRORS, "ENCRYPT: buffer size error, bc=%d bo=%d bl=%d wc=%d wo=%d wl=%d cbs=%d", - buf->capacity, - buf->offset, - buf->len, - work.capacity, - work.offset, - work.len, - cipher_ctx_block_size (ctx->cipher)); - goto err; - } - - /* Encrypt packet ID, payload */ - ASSERT (cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf), BLEN (buf))); - work.len += outlen; - - /* Flush the encryption buffer */ - ASSERT(cipher_ctx_final(ctx->cipher, BPTR (&work) + outlen, &outlen)); - work.len += outlen; - ASSERT (outlen == iv_size); - - /* prepend the IV to the ciphertext */ - if (opt->flags & CO_USE_IV) - { - uint8_t *output = buf_prepend (&work, iv_size); - ASSERT (output); - memcpy (output, iv_buf, iv_size); - } - - dmsg (D_PACKET_CONTENT, "ENCRYPT TO: %s", - format_hex (BPTR (&work), BLEN (&work), 80, &gc)); - } - else /* No Encryption */ - { - if (opt->packet_id) - { - struct packet_id_net pin; - packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)); - ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true)); - } - work = *buf; - } - - /* HMAC the ciphertext (or plaintext if !cipher) */ - if (ctx->hmac) - { - uint8_t *output = NULL; - - hmac_ctx_reset (ctx->hmac); - hmac_ctx_update (ctx->hmac, BPTR(&work), BLEN(&work)); - output = buf_prepend (&work, hmac_ctx_size(ctx->hmac)); - ASSERT (output); - hmac_ctx_final (ctx->hmac, output); - } - - *buf = work; - } - - gc_free (&gc); - return; - -err: - crypto_clear_error(); - buf->len = 0; - gc_free (&gc); - return; -} - -/* - * If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet. - * - * Set buf->len to 0 and return false on decrypt error. - * - * On success, buf is set to point to plaintext, true - * is returned. - */ -bool -openvpn_decrypt (struct buffer *buf, struct buffer work, - const struct crypto_options *opt, - const struct frame* frame) -{ - static const char error_prefix[] = "Authenticate/Decrypt packet error"; - struct gc_arena gc; - gc_init (&gc); - - if (buf->len > 0 && opt->key_ctx_bi) - { - struct key_ctx *ctx = &opt->key_ctx_bi->decrypt; - struct packet_id_net pin; - bool have_pin = false; - - /* Verify the HMAC */ - if (ctx->hmac) - { - int hmac_len; - uint8_t local_hmac[MAX_HMAC_KEY_LENGTH]; /* HMAC of ciphertext computed locally */ - - hmac_ctx_reset(ctx->hmac); - - /* Assume the length of the input HMAC */ - hmac_len = hmac_ctx_size (ctx->hmac); - - /* Authentication fails if insufficient data in packet for HMAC */ - if (buf->len < hmac_len) - CRYPT_ERROR ("missing authentication info"); - - hmac_ctx_update (ctx->hmac, BPTR (buf) + hmac_len, BLEN (buf) - hmac_len); - hmac_ctx_final (ctx->hmac, local_hmac); - - /* Compare locally computed HMAC with packet HMAC */ - if (memcmp (local_hmac, BPTR (buf), hmac_len)) - CRYPT_ERROR ("packet HMAC authentication failed"); - - ASSERT (buf_advance (buf, hmac_len)); - } - - /* Decrypt packet ID + payload */ - - if (ctx->cipher) - { - const unsigned int mode = cipher_ctx_mode (ctx->cipher); - const int iv_size = cipher_ctx_iv_length (ctx->cipher); - uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH]; - int outlen; - - /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */ - ASSERT (buf_init (&work, FRAME_HEADROOM_ADJ (frame, FRAME_HEADROOM_MARKER_DECRYPT))); - - /* use IV if user requested it */ - CLEAR (iv_buf); - if (opt->flags & CO_USE_IV) - { - if (buf->len < iv_size) - CRYPT_ERROR ("missing IV info"); - memcpy (iv_buf, BPTR (buf), iv_size); - ASSERT (buf_advance (buf, iv_size)); - } - - /* show the IV's initial state */ - if (opt->flags & CO_USE_IV) - dmsg (D_PACKET_CONTENT, "DECRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc)); - - if (buf->len < 1) - CRYPT_ERROR ("missing payload"); - - /* ctx->cipher was already initialized with key & keylen */ - if (!cipher_ctx_reset (ctx->cipher, iv_buf)) - CRYPT_ERROR ("cipher init failed"); - - /* Buffer overflow check (should never happen) */ - if (!buf_safe (&work, buf->len)) - CRYPT_ERROR ("buffer overflow"); - - /* Decrypt packet ID, payload */ - if (!cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf), BLEN (buf))) - CRYPT_ERROR ("cipher update failed"); - work.len += outlen; - - /* Flush the decryption buffer */ - if (!cipher_ctx_final (ctx->cipher, BPTR (&work) + outlen, &outlen)) - CRYPT_ERROR ("cipher final failed"); - work.len += outlen; - - dmsg (D_PACKET_CONTENT, "DECRYPT TO: %s", - format_hex (BPTR (&work), BLEN (&work), 80, &gc)); - - /* Get packet ID from plaintext buffer or IV, depending on cipher mode */ - { - if (mode == OPENVPN_MODE_CBC) - { - if (opt->packet_id) - { - if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM))) - CRYPT_ERROR ("error reading CBC packet-id"); - have_pin = true; - } - } - else if (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB) - { - struct buffer b; - - ASSERT (opt->flags & CO_USE_IV); /* IV and packet-ID required */ - ASSERT (opt->packet_id); /* for this mode. */ - - buf_set_read (&b, iv_buf, iv_size); - if (!packet_id_read (&pin, &b, true)) - CRYPT_ERROR ("error reading CFB/OFB packet-id"); - have_pin = true; - } - else /* We only support CBC, CFB, or OFB modes right now */ - { - ASSERT (0); - } - } - } - else - { - work = *buf; - if (opt->packet_id) - { - if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM))) - CRYPT_ERROR ("error reading packet-id"); - have_pin = !BOOL_CAST (opt->flags & CO_IGNORE_PACKET_ID); - } - } - - if (have_pin) - { - packet_id_reap_test (&opt->packet_id->rec); - if (packet_id_test (&opt->packet_id->rec, &pin)) - { - packet_id_add (&opt->packet_id->rec, &pin); - if (opt->pid_persist && (opt->flags & CO_PACKET_ID_LONG_FORM)) - packet_id_persist_save_obj (opt->pid_persist, opt->packet_id); - } - else - { - if (!(opt->flags & CO_MUTE_REPLAY_WARNINGS)) - msg (D_REPLAY_ERRORS, "%s: bad packet ID (may be a replay): %s -- see the man page entry for --no-replay and --replay-window for more info or silence this warning with --mute-replay-warnings", - error_prefix, packet_id_net_print (&pin, true, &gc)); - goto error_exit; - } - } - *buf = work; - } - - gc_free (&gc); - return true; - - error_exit: - crypto_clear_error(); - buf->len = 0; - gc_free (&gc); - return false; -} - -/* - * How many bytes will we add to frame buffer for a given - * set of crypto options? - */ -void -crypto_adjust_frame_parameters(struct frame *frame, - const struct key_type* kt, - bool cipher_defined, - bool use_iv, - bool packet_id, - bool packet_id_long_form) -{ - frame_add_to_extra_frame (frame, - (packet_id ? packet_id_size (packet_id_long_form) : 0) + - ((cipher_defined && use_iv) ? cipher_kt_iv_size (kt->cipher) : 0) + - (cipher_defined ? cipher_kt_block_size (kt->cipher) : 0) + /* worst case padding expansion */ - kt->hmac_length); -} - -/* - * Build a struct key_type. - */ -void -init_key_type (struct key_type *kt, const char *ciphername, - bool ciphername_defined, const char *authname, - bool authname_defined, int keysize, - bool cfb_ofb_allowed, bool warn) -{ - CLEAR (*kt); - if (ciphername && ciphername_defined) - { - kt->cipher = cipher_kt_get (ciphername); - kt->cipher_length = cipher_kt_key_size (kt->cipher); - if (keysize > 0 && keysize <= MAX_CIPHER_KEY_LENGTH) - kt->cipher_length = keysize; - - /* check legal cipher mode */ - { - const unsigned int mode = cipher_kt_mode (kt->cipher); - if (!(mode == OPENVPN_MODE_CBC -#ifdef ALLOW_NON_CBC_CIPHERS - || (cfb_ofb_allowed && (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB)) -#endif - )) -#ifdef ENABLE_SMALL - msg (M_FATAL, "Cipher '%s' mode not supported", ciphername); -#else - msg (M_FATAL, "Cipher '%s' uses a mode not supported by " PACKAGE_NAME " in your current configuration. CBC mode is always supported, while CFB and OFB modes are supported only when using SSL/TLS authentication and key exchange mode, and when " PACKAGE_NAME " has been built with ALLOW_NON_CBC_CIPHERS.", ciphername); -#endif - } - } - else - { - if (warn) - msg (M_WARN, "******* WARNING *******: null cipher specified, no encryption will be used"); - } - if (authname && authname_defined) - { - kt->digest = md_kt_get (authname); - kt->hmac_length = md_kt_size (kt->digest); - } - else - { - if (warn) - msg (M_WARN, "******* WARNING *******: null MAC specified, no authentication will be used"); - } -} - -/* given a key and key_type, build a key_ctx */ -void -init_key_ctx (struct key_ctx *ctx, struct key *key, - const struct key_type *kt, int enc, - const char *prefix) -{ - struct gc_arena gc = gc_new (); - CLEAR (*ctx); - if (kt->cipher && kt->cipher_length > 0) - { - - ALLOC_OBJ(ctx->cipher, cipher_ctx_t); - cipher_ctx_init (ctx->cipher, key->cipher, kt->cipher_length, - kt->cipher, enc); - - msg (D_HANDSHAKE, "%s: Cipher '%s' initialized with %d bit key", - prefix, - cipher_kt_name(kt->cipher), - kt->cipher_length *8); - - dmsg (D_SHOW_KEYS, "%s: CIPHER KEY: %s", prefix, - format_hex (key->cipher, kt->cipher_length, 0, &gc)); - dmsg (D_CRYPTO_DEBUG, "%s: CIPHER block_size=%d iv_size=%d", - prefix, - cipher_kt_block_size(kt->cipher), - cipher_kt_iv_size(kt->cipher)); - } - if (kt->digest && kt->hmac_length > 0) - { - ALLOC_OBJ(ctx->hmac, hmac_ctx_t); - hmac_ctx_init (ctx->hmac, key->hmac, kt->hmac_length, kt->digest); - - msg (D_HANDSHAKE, - "%s: Using %d bit message hash '%s' for HMAC authentication", - prefix, md_kt_size(kt->digest) * 8, md_kt_name(kt->digest)); - - dmsg (D_SHOW_KEYS, "%s: HMAC KEY: %s", prefix, - format_hex (key->hmac, kt->hmac_length, 0, &gc)); - - dmsg (D_CRYPTO_DEBUG, "%s: HMAC size=%d block_size=%d", - prefix, - md_kt_size(kt->digest), - hmac_ctx_size(ctx->hmac)); - - } - gc_free (&gc); -} - -void -free_key_ctx (struct key_ctx *ctx) -{ - if (ctx->cipher) - { - cipher_ctx_cleanup(ctx->cipher); - free(ctx->cipher); - ctx->cipher = NULL; - } - if (ctx->hmac) - { - hmac_ctx_cleanup(ctx->hmac); - free(ctx->hmac); - ctx->hmac = NULL; - } -} - -void -free_key_ctx_bi (struct key_ctx_bi *ctx) -{ - free_key_ctx(&ctx->encrypt); - free_key_ctx(&ctx->decrypt); -} - - -static bool -key_is_zero (struct key *key, const struct key_type *kt) -{ - int i; - for (i = 0; i < kt->cipher_length; ++i) - if (key->cipher[i]) - return false; - msg (D_CRYPT_ERRORS, "CRYPTO INFO: WARNING: zero key detected"); - return true; -} - -/* - * Make sure that cipher key is a valid key for current key_type. - */ -bool -check_key (struct key *key, const struct key_type *kt) -{ - if (kt->cipher) - { - /* - * Check for zero key - */ - if (key_is_zero(key, kt)) - return false; - - /* - * Check for weak or semi-weak DES keys. - */ - { - const int ndc = key_des_num_cblocks (kt->cipher); - if (ndc) - return key_des_check (key->cipher, kt->cipher_length, ndc); - else - return true; - } - } - return true; -} - -/* - * Make safe mutations to key to ensure it is valid, - * such as ensuring correct parity on DES keys. - * - * This routine cannot guarantee it will generate a good - * key. You must always call check_key after this routine - * to make sure. - */ -void -fixup_key (struct key *key, const struct key_type *kt) -{ - struct gc_arena gc = gc_new (); - if (kt->cipher) - { -#ifdef ENABLE_DEBUG - const struct key orig = *key; -#endif - const int ndc = key_des_num_cblocks (kt->cipher); - - if (ndc) - key_des_fixup (key->cipher, kt->cipher_length, ndc); - -#ifdef ENABLE_DEBUG - if (check_debug_level (D_CRYPTO_DEBUG)) - { - if (memcmp (orig.cipher, key->cipher, kt->cipher_length)) - dmsg (D_CRYPTO_DEBUG, "CRYPTO INFO: fixup_key: before=%s after=%s", - format_hex (orig.cipher, kt->cipher_length, 0, &gc), - format_hex (key->cipher, kt->cipher_length, 0, &gc)); - } -#endif - } - gc_free (&gc); -} - -void -check_replay_iv_consistency (const struct key_type *kt, bool packet_id, bool use_iv) -{ - if (cfb_ofb_mode (kt) && !(packet_id && use_iv)) - msg (M_FATAL, "--no-replay or --no-iv cannot be used with a CFB or OFB mode cipher"); -} - -bool -cfb_ofb_mode (const struct key_type* kt) -{ - if (kt && kt->cipher) { - const unsigned int mode = cipher_kt_mode (kt->cipher); - return mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB; - } - return false; -} - -/* - * Generate a random key. If key_type is provided, make - * sure generated key is valid for key_type. - */ -void -generate_key_random (struct key *key, const struct key_type *kt) -{ - int cipher_len = MAX_CIPHER_KEY_LENGTH; - int hmac_len = MAX_HMAC_KEY_LENGTH; - - struct gc_arena gc = gc_new (); - - do { - CLEAR (*key); - if (kt) - { - if (kt->cipher && kt->cipher_length > 0 && kt->cipher_length <= cipher_len) - cipher_len = kt->cipher_length; - - if (kt->digest && kt->hmac_length > 0 && kt->hmac_length <= hmac_len) - hmac_len = kt->hmac_length; - } - if (!rand_bytes (key->cipher, cipher_len) - || !rand_bytes (key->hmac, hmac_len)) - msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for key generation"); - - dmsg (D_SHOW_KEY_SOURCE, "Cipher source entropy: %s", format_hex (key->cipher, cipher_len, 0, &gc)); - dmsg (D_SHOW_KEY_SOURCE, "HMAC source entropy: %s", format_hex (key->hmac, hmac_len, 0, &gc)); - - if (kt) - fixup_key (key, kt); - } while (kt && !check_key (key, kt)); - - gc_free (&gc); -} - -/* - * Print key material - */ -void -key2_print (const struct key2* k, - const struct key_type *kt, - const char* prefix0, - const char* prefix1) -{ - struct gc_arena gc = gc_new (); - ASSERT (k->n == 2); - dmsg (D_SHOW_KEY_SOURCE, "%s (cipher): %s", - prefix0, - format_hex (k->keys[0].cipher, kt->cipher_length, 0, &gc)); - dmsg (D_SHOW_KEY_SOURCE, "%s (hmac): %s", - prefix0, - format_hex (k->keys[0].hmac, kt->hmac_length, 0, &gc)); - dmsg (D_SHOW_KEY_SOURCE, "%s (cipher): %s", - prefix1, - format_hex (k->keys[1].cipher, kt->cipher_length, 0, &gc)); - dmsg (D_SHOW_KEY_SOURCE, "%s (hmac): %s", - prefix1, - format_hex (k->keys[1].hmac, kt->hmac_length, 0, &gc)); - gc_free (&gc); -} - -void -test_crypto (const struct crypto_options *co, struct frame* frame) -{ - int i, j; - struct gc_arena gc = gc_new (); - struct buffer src = alloc_buf_gc (TUN_MTU_SIZE (frame), &gc); - struct buffer work = alloc_buf_gc (BUF_SIZE (frame), &gc); - struct buffer encrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc); - struct buffer decrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc); - struct buffer buf = clear_buf(); - - /* init work */ - ASSERT (buf_init (&work, FRAME_HEADROOM (frame))); - - msg (M_INFO, "Entering " PACKAGE_NAME " crypto self-test mode."); - for (i = 1; i <= TUN_MTU_SIZE (frame); ++i) - { - update_time (); - - msg (M_INFO, "TESTING ENCRYPT/DECRYPT of packet length=%d", i); - - /* - * Load src with random data. - */ - ASSERT (buf_init (&src, 0)); - ASSERT (i <= src.capacity); - src.len = i; - ASSERT (rand_bytes (BPTR (&src), BLEN (&src))); - - /* copy source to input buf */ - buf = work; - memcpy (buf_write_alloc (&buf, BLEN (&src)), BPTR (&src), BLEN (&src)); - - /* encrypt */ - openvpn_encrypt (&buf, encrypt_workspace, co, frame); - - /* decrypt */ - openvpn_decrypt (&buf, decrypt_workspace, co, frame); - - /* compare */ - if (buf.len != src.len) - msg (M_FATAL, "SELF TEST FAILED, src.len=%d buf.len=%d", src.len, buf.len); - for (j = 0; j < i; ++j) - { - const uint8_t in = *(BPTR (&src) + j); - const uint8_t out = *(BPTR (&buf) + j); - if (in != out) - msg (M_FATAL, "SELF TEST FAILED, pos=%d in=%d out=%d", j, in, out); - } - } - msg (M_INFO, PACKAGE_NAME " crypto self-test mode SUCCEEDED."); - gc_free (&gc); -} - -#ifdef ENABLE_SSL - -void -get_tls_handshake_key (const struct key_type *key_type, - struct key_ctx_bi *ctx, - const char *passphrase_file, - const int key_direction, - const unsigned int flags) -{ - if (passphrase_file && key_type->hmac_length) - { - struct key2 key2; - struct key_type kt = *key_type; - struct key_direction_state kds; - - /* for control channel we are only authenticating, not encrypting */ - kt.cipher_length = 0; - kt.cipher = NULL; - - if (flags & GHK_INLINE) - { - /* key was specified inline, key text is in passphrase_file */ - read_key_file (&key2, passphrase_file, RKF_INLINE|RKF_MUST_SUCCEED); - - /* succeeded? */ - if (key2.n == 2) - msg (M_INFO, "Control Channel Authentication: tls-auth using INLINE static key file"); - else - msg (M_FATAL, "INLINE tls-auth file lacks the requisite 2 keys"); - } - else - { - /* first try to parse as an OpenVPN static key file */ - read_key_file (&key2, passphrase_file, 0); - - /* succeeded? */ - if (key2.n == 2) - { - msg (M_INFO, - "Control Channel Authentication: using '%s' as a " PACKAGE_NAME " static key file", - passphrase_file); - } - else - { - int hash_size; - - CLEAR (key2); - - /* failed, now try to get hash from a freeform file */ - hash_size = read_passphrase_hash (passphrase_file, - kt.digest, - key2.keys[0].hmac, - MAX_HMAC_KEY_LENGTH); - ASSERT (hash_size == kt.hmac_length); - - /* suceeded */ - key2.n = 1; - - msg (M_INFO, - "Control Channel Authentication: using '%s' as a free-form passphrase file", - passphrase_file); - } - } - /* handle key direction */ - - key_direction_state_init (&kds, key_direction); - must_have_n_keys (passphrase_file, "tls-auth", &key2, kds.need_keys); - - /* initialize hmac key in both directions */ - - init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], &kt, OPENVPN_OP_ENCRYPT, - "Outgoing Control Channel Authentication"); - init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], &kt, OPENVPN_OP_DECRYPT, - "Incoming Control Channel Authentication"); - - CLEAR (key2); - } - else - { - CLEAR (*ctx); - } -} -#endif - -/* header and footer for static key file */ -static const char static_key_head[] = "-----BEGIN OpenVPN Static key V1-----"; -static const char static_key_foot[] = "-----END OpenVPN Static key V1-----"; - -static const char printable_char_fmt[] = - "Non-Hex character ('%c') found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)"; - -static const char unprintable_char_fmt[] = - "Non-Hex, unprintable character (0x%02x) found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)"; - -/* read key from file */ - -void -read_key_file (struct key2 *key2, const char *file, const unsigned int flags) -{ - struct gc_arena gc = gc_new (); - struct buffer in; - int fd, size; - uint8_t hex_byte[3] = {0, 0, 0}; - const char *error_filename = file; - - /* parse info */ - const unsigned char *cp; - int hb_index = 0; - int line_num = 1; - int line_index = 0; - int match = 0; - - /* output */ - uint8_t* out = (uint8_t*) &key2->keys; - const int keylen = sizeof (key2->keys); - int count = 0; - - /* parse states */ -# define PARSE_INITIAL 0 -# define PARSE_HEAD 1 -# define PARSE_DATA 2 -# define PARSE_DATA_COMPLETE 3 -# define PARSE_FOOT 4 -# define PARSE_FINISHED 5 - int state = PARSE_INITIAL; - - /* constants */ - const int hlen = strlen (static_key_head); - const int flen = strlen (static_key_foot); - const int onekeylen = sizeof (key2->keys[0]); - - CLEAR (*key2); - - /* - * Key can be provided as a filename in 'file' or if RKF_INLINE - * is set, the actual key data itself in ascii form. - */ - if (flags & RKF_INLINE) /* 'file' is a string containing ascii representation of key */ - { - size = strlen (file) + 1; - buf_set_read (&in, (const uint8_t *)file, size); - error_filename = INLINE_FILE_TAG; - } - else /* 'file' is a filename which refers to a file containing the ascii key */ - { - in = alloc_buf_gc (2048, &gc); - fd = platform_open (file, O_RDONLY, 0); - if (fd == -1) - msg (M_ERR, "Cannot open file key file '%s'", file); - size = read (fd, in.data, in.capacity); - if (size < 0) - msg (M_FATAL, "Read error on key file ('%s')", file); - if (size == in.capacity) - msg (M_FATAL, "Key file ('%s') can be a maximum of %d bytes", file, (int)in.capacity); - close (fd); - } - - cp = (unsigned char *)in.data; - while (size > 0) - { - const unsigned char c = *cp; - -#if 0 - msg (M_INFO, "char='%c'[%d] s=%d ln=%d li=%d m=%d c=%d", - c, (int)c, state, line_num, line_index, match, count); -#endif - - if (c == '\n') - { - line_index = match = 0; - ++line_num; - } - else - { - /* first char of new line */ - if (!line_index) - { - /* first char of line after header line? */ - if (state == PARSE_HEAD) - state = PARSE_DATA; - - /* first char of footer */ - if ((state == PARSE_DATA || state == PARSE_DATA_COMPLETE) && c == '-') - state = PARSE_FOOT; - } - - /* compare read chars with header line */ - if (state == PARSE_INITIAL) - { - if (line_index < hlen && c == static_key_head[line_index]) - { - if (++match == hlen) - state = PARSE_HEAD; - } - } - - /* compare read chars with footer line */ - if (state == PARSE_FOOT) - { - if (line_index < flen && c == static_key_foot[line_index]) - { - if (++match == flen) - state = PARSE_FINISHED; - } - } - - /* reading key */ - if (state == PARSE_DATA) - { - if (isxdigit(c)) - { - ASSERT (hb_index >= 0 && hb_index < 2); - hex_byte[hb_index++] = c; - if (hb_index == 2) - { - unsigned int u; - ASSERT(sscanf((const char *)hex_byte, "%x", &u) == 1); - *out++ = u; - hb_index = 0; - if (++count == keylen) - state = PARSE_DATA_COMPLETE; - } - } - else if (isspace(c)) - ; - else - { - msg (M_FATAL, - (isprint (c) ? printable_char_fmt : unprintable_char_fmt), - c, line_num, error_filename, count, onekeylen, keylen); - } - } - ++line_index; - } - ++cp; - --size; - } - - /* - * Normally we will read either 1 or 2 keys from file. - */ - key2->n = count / onekeylen; - - ASSERT (key2->n >= 0 && key2->n <= (int) SIZE (key2->keys)); - - if (flags & RKF_MUST_SUCCEED) - { - if (!key2->n) - msg (M_FATAL, "Insufficient key material or header text not found in file '%s' (%d/%d/%d bytes found/min/max)", - error_filename, count, onekeylen, keylen); - - if (state != PARSE_FINISHED) - msg (M_FATAL, "Footer text not found in file '%s' (%d/%d/%d bytes found/min/max)", - error_filename, count, onekeylen, keylen); - } - - /* zero file read buffer if not an inline file */ - if (!(flags & RKF_INLINE)) - buf_clear (&in); - - if (key2->n) - warn_if_group_others_accessible (error_filename); - -#if 0 - /* DEBUGGING */ - { - int i; - printf ("KEY READ, n=%d\n", key2->n); - for (i = 0; i < (int) SIZE (key2->keys); ++i) - { - /* format key as ascii */ - const char *fmt = format_hex_ex ((const uint8_t*)&key2->keys[i], - sizeof (key2->keys[i]), - 0, - 16, - "\n", - &gc); - printf ("[%d]\n%s\n\n", i, fmt); - } - } -#endif - - /* pop our garbage collection level */ - gc_free (&gc); -} - -int -read_passphrase_hash (const char *passphrase_file, - const md_kt_t *digest, - uint8_t *output, - int len) -{ - unsigned int outlen = 0; - md_ctx_t md; - - ASSERT (len >= md_kt_size(digest)); - memset (output, 0, len); - - md_ctx_init(&md, digest); - - /* read passphrase file */ - { - const int min_passphrase_size = 8; - uint8_t buf[64]; - int total_size = 0; - int fd = platform_open (passphrase_file, O_RDONLY, 0); - - if (fd == -1) - msg (M_ERR, "Cannot open passphrase file: '%s'", passphrase_file); - - for (;;) - { - int size = read (fd, buf, sizeof (buf)); - if (size == 0) - break; - if (size == -1) - msg (M_ERR, "Read error on passphrase file: '%s'", - passphrase_file); - md_ctx_update(&md, buf, size); - total_size += size; - } - close (fd); - - warn_if_group_others_accessible (passphrase_file); - - if (total_size < min_passphrase_size) - msg (M_FATAL, - "Passphrase file '%s' is too small (must have at least %d characters)", - passphrase_file, min_passphrase_size); - } - md_ctx_final(&md, output); - md_ctx_cleanup(&md); - return md_kt_size(digest); -} - -/* - * Write key to file, return number of random bits - * written. - */ -int -write_key_file (const int nkeys, const char *filename) -{ - struct gc_arena gc = gc_new (); - - int fd, i; - int nbits = 0; - - /* must be large enough to hold full key file */ - struct buffer out = alloc_buf_gc (2048, &gc); - struct buffer nbits_head_text = alloc_buf_gc (128, &gc); - - /* how to format the ascii file representation of key */ - const int bytes_per_line = 16; - - /* open key file */ - fd = platform_open (filename, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR); - - if (fd == -1) - msg (M_ERR, "Cannot open shared secret file '%s' for write", filename); - - buf_printf (&out, "%s\n", static_key_head); - - for (i = 0; i < nkeys; ++i) - { - struct key key; - char* fmt; - - /* generate random bits */ - generate_key_random (&key, NULL); - - /* format key as ascii */ - fmt = format_hex_ex ((const uint8_t*)&key, - sizeof (key), - 0, - bytes_per_line, - "\n", - &gc); - - /* increment random bits counter */ - nbits += sizeof (key) * 8; - - /* write to holding buffer */ - buf_printf (&out, "%s\n", fmt); - - /* zero memory which held key component (will be freed by GC) */ - memset (fmt, 0, strlen(fmt)); - CLEAR (key); - } - - buf_printf (&out, "%s\n", static_key_foot); - - /* write number of bits */ - buf_printf (&nbits_head_text, "#\n# %d bit OpenVPN static key\n#\n", nbits); - buf_write_string_file (&nbits_head_text, filename, fd); - - /* write key file, now formatted in out, to file */ - buf_write_string_file (&out, filename, fd); - - if (close (fd)) - msg (M_ERR, "Close error on shared secret file %s", filename); - - /* zero memory which held file content (memory will be freed by GC) */ - buf_clear (&out); - - /* pop our garbage collection level */ - gc_free (&gc); - - return nbits; -} - -void -must_have_n_keys (const char *filename, const char *option, const struct key2 *key2, int n) -{ - if (key2->n < n) - { -#ifdef ENABLE_SMALL - msg (M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d]", filename, option, key2->n, n); -#else - msg (M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d] -- try generating a new key file with '" PACKAGE " --genkey --secret [file]', or use the existing key file in bidirectional mode by specifying --%s without a key direction parameter", filename, option, key2->n, n, option); -#endif - } -} - -int -ascii2keydirection (int msglevel, const char *str) -{ - if (!str) - return KEY_DIRECTION_BIDIRECTIONAL; - else if (!strcmp (str, "0")) - return KEY_DIRECTION_NORMAL; - else if (!strcmp (str, "1")) - return KEY_DIRECTION_INVERSE; - else - { - msg (msglevel, "Unknown key direction '%s' -- must be '0' or '1'", str); - return -1; - } - return KEY_DIRECTION_BIDIRECTIONAL; /* NOTREACHED */ -} - -const char * -keydirection2ascii (int kd, bool remote) -{ - if (kd == KEY_DIRECTION_BIDIRECTIONAL) - return NULL; - else if (kd == KEY_DIRECTION_NORMAL) - return remote ? "1" : "0"; - else if (kd == KEY_DIRECTION_INVERSE) - return remote ? "0" : "1"; - else - { - ASSERT (0); - } - return NULL; /* NOTREACHED */ -} - -void -key_direction_state_init (struct key_direction_state *kds, int key_direction) -{ - CLEAR (*kds); - switch (key_direction) - { - case KEY_DIRECTION_NORMAL: - kds->out_key = 0; - kds->in_key = 1; - kds->need_keys = 2; - break; - case KEY_DIRECTION_INVERSE: - kds->out_key = 1; - kds->in_key = 0; - kds->need_keys = 2; - break; - case KEY_DIRECTION_BIDIRECTIONAL: - kds->out_key = 0; - kds->in_key = 0; - kds->need_keys = 1; - break; - default: - ASSERT (0); - } -} - -void -verify_fix_key2 (struct key2 *key2, const struct key_type *kt, const char *shared_secret_file) -{ - int i; - - for (i = 0; i < key2->n; ++i) - { - /* Fix parity for DES keys and make sure not a weak key */ - fixup_key (&key2->keys[i], kt); - - /* This should be a very improbable failure */ - if (!check_key (&key2->keys[i], kt)) - msg (M_FATAL, "Key #%d in '%s' is bad. Try making a new key with --genkey.", - i+1, shared_secret_file); - } -} - -/* given a key and key_type, write key to buffer */ -bool -write_key (const struct key *key, const struct key_type *kt, - struct buffer *buf) -{ - ASSERT (kt->cipher_length <= MAX_CIPHER_KEY_LENGTH - && kt->hmac_length <= MAX_HMAC_KEY_LENGTH); - - if (!buf_write (buf, &kt->cipher_length, 1)) - return false; - if (!buf_write (buf, &kt->hmac_length, 1)) - return false; - if (!buf_write (buf, key->cipher, kt->cipher_length)) - return false; - if (!buf_write (buf, key->hmac, kt->hmac_length)) - return false; - - return true; -} - -/* - * Given a key_type and buffer, read key from buffer. - * Return: 1 on success - * -1 read failure - * 0 on key length mismatch - */ -int -read_key (struct key *key, const struct key_type *kt, struct buffer *buf) -{ - uint8_t cipher_length; - uint8_t hmac_length; - - CLEAR (*key); - if (!buf_read (buf, &cipher_length, 1)) - goto read_err; - if (!buf_read (buf, &hmac_length, 1)) - goto read_err; - - if (!buf_read (buf, key->cipher, cipher_length)) - goto read_err; - if (!buf_read (buf, key->hmac, hmac_length)) - goto read_err; - - if (cipher_length != kt->cipher_length || hmac_length != kt->hmac_length) - goto key_len_err; - - return 1; - -read_err: - msg (D_TLS_ERRORS, "TLS Error: error reading key from remote"); - return -1; - -key_len_err: - msg (D_TLS_ERRORS, - "TLS Error: key length mismatch, local cipher/hmac %d/%d, remote cipher/hmac %d/%d", - kt->cipher_length, kt->hmac_length, cipher_length, hmac_length); - return 0; -} - -/* - * Random number functions, used in cases where we want - * reasonably strong cryptographic random number generation - * without depleting our entropy pool. Used for random - * IV values and a number of other miscellaneous tasks. - */ - -static uint8_t *nonce_data = NULL; /* GLOBAL */ -static const md_kt_t *nonce_md = NULL; /* GLOBAL */ -static int nonce_secret_len = 0; /* GLOBAL */ - -/* Reset the nonce value, also done periodically to refresh entropy */ -static void -prng_reset_nonce () -{ - const int size = md_kt_size (nonce_md) + nonce_secret_len; -#if 1 /* Must be 1 for real usage */ - if (!rand_bytes (nonce_data, size)) - msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for PRNG"); -#else - /* Only for testing -- will cause a predictable PRNG sequence */ - { - int i; - for (i = 0; i < size; ++i) - nonce_data[i] = (uint8_t) i; - } -#endif -} - -void -prng_init (const char *md_name, const int nonce_secret_len_parm) -{ - prng_uninit (); - nonce_md = md_name ? md_kt_get (md_name) : NULL; - if (nonce_md) - { - ASSERT (nonce_secret_len_parm >= NONCE_SECRET_LEN_MIN && nonce_secret_len_parm <= NONCE_SECRET_LEN_MAX); - nonce_secret_len = nonce_secret_len_parm; - { - const int size = md_kt_size(nonce_md) + nonce_secret_len; - dmsg (D_CRYPTO_DEBUG, "PRNG init md=%s size=%d", md_kt_name(nonce_md), size); - nonce_data = (uint8_t*) malloc (size); - check_malloc_return (nonce_data); - prng_reset_nonce(); - } - } -} - -void -prng_uninit (void) -{ - free (nonce_data); - nonce_data = NULL; - nonce_md = NULL; - nonce_secret_len = 0; -} - -void -prng_bytes (uint8_t *output, int len) -{ - static size_t processed = 0; - - if (nonce_md) - { - const int md_size = md_kt_size (nonce_md); - while (len > 0) - { - unsigned int outlen = 0; - const int blen = min_int (len, md_size); - md_full(nonce_md, nonce_data, md_size + nonce_secret_len, nonce_data); - memcpy (output, nonce_data, blen); - output += blen; - len -= blen; - - /* Ensure that random data is reset regularly */ - processed += blen; - if(processed > PRNG_NONCE_RESET_BYTES) { - prng_reset_nonce(); - processed = 0; - } - } - } - else - rand_bytes (output, len); -} - -/* an analogue to the random() function, but use prng_bytes */ -long int -get_random() -{ - long int l; - prng_bytes ((unsigned char *)&l, sizeof(l)); - if (l < 0) - l = -l; - return l; -} - -#ifndef ENABLE_SSL - -void -init_ssl_lib (void) -{ - crypto_init_lib (); -} - -void -free_ssl_lib (void) -{ - crypto_uninit_lib (); - prng_uninit(); -} - -#endif /* ENABLE_SSL */ - -/* - * md5 functions - */ - -const char * -md5sum (uint8_t *buf, int len, int n_print_chars, struct gc_arena *gc) -{ - uint8_t digest[MD5_DIGEST_LENGTH]; - const md_kt_t *md5_kt = md_kt_get("MD5"); - - md_full(md5_kt, buf, len, digest); - - return format_hex (digest, MD5_DIGEST_LENGTH, n_print_chars, gc); -} - -void -md5_state_init (struct md5_state *s) -{ - const md_kt_t *md5_kt = md_kt_get("MD5"); - - md_ctx_init(&s->ctx, md5_kt); -} - -void -md5_state_update (struct md5_state *s, void *data, size_t len) -{ - md_ctx_update(&s->ctx, data, len); -} - -void -md5_state_final (struct md5_state *s, struct md5_digest *out) -{ - md_ctx_final(&s->ctx, out->digest); - md_ctx_cleanup(&s->ctx); -} - -void -md5_digest_clear (struct md5_digest *digest) -{ - CLEAR (*digest); -} - -bool -md5_digest_defined (const struct md5_digest *digest) -{ - int i; - for (i = 0; i < MD5_DIGEST_LENGTH; ++i) - if (digest->digest[i]) - return true; - return false; -} - -bool -md5_digest_equal (const struct md5_digest *d1, const struct md5_digest *d2) -{ - return memcmp(d1->digest, d2->digest, MD5_DIGEST_LENGTH) == 0; -} - -#endif /* ENABLE_CRYPTO */ |