diff options
Diffstat (limited to 'src/methods/generic_gcm')
| -rw-r--r-- | src/methods/generic_gcm/CMakeLists.txt | 6 | ||||
| -rw-r--r-- | src/methods/generic_gcm/generic_gcm.c | 283 |
2 files changed, 289 insertions, 0 deletions
diff --git a/src/methods/generic_gcm/CMakeLists.txt b/src/methods/generic_gcm/CMakeLists.txt new file mode 100644 index 0000000..1771ee0 --- /dev/null +++ b/src/methods/generic_gcm/CMakeLists.txt @@ -0,0 +1,6 @@ +include_directories(${FASTD_SOURCE_DIR}/src ${FASTD_BINARY_DIR}) + +add_library(method_generic_gcm OBJECT + generic_gcm.c +) +set_property(TARGET method_generic_gcm PROPERTY COMPILE_FLAGS "${FASTD_CFLAGS}") diff --git a/src/methods/generic_gcm/generic_gcm.c b/src/methods/generic_gcm/generic_gcm.c new file mode 100644 index 0000000..479ea83 --- /dev/null +++ b/src/methods/generic_gcm/generic_gcm.c @@ -0,0 +1,283 @@ +/* + Copyright (c) 2012-2013, Matthias Schiffer <mschiffer@universe-factory.net> + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright notice, + this list of conditions and the following disclaimer. + 2. Redistributions in binary form must reproduce the above copyright notice, + this list of conditions and the following disclaimer in the documentation + and/or other materials provided with the distribution. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE + FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER + CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ + + +#include "../../fastd.h" +#include "../../crypto.h" +#include "../common.h" + + +struct fastd_method_session_state { + fastd_method_common_t common; + + const fastd_cipher_t *cipher; + fastd_cipher_context_t *cipher_ctx; + fastd_cipher_state_t *cipher_state; + + fastd_crypto_ghash_state_t *cstate_ghash; +}; + + +static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_t **cipher, fastd_cipher_context_t **cctx) { + size_t len = strlen(name); + + if (len < 4) + return NULL; + + if (strcmp(name+len-4, "-gcm")) + return NULL; + + char name_ctr[len+1]; + memcpy(name_ctr, name, len-3); + strncpy(name_ctr+len-3, "ctr", 4); + + if (ctx) { + *cipher = fastd_cipher_get_by_name(ctx, name_ctr, cctx); + return *cipher; + } + else { + return fastd_cipher_available(name_ctr); + } +} + + +static bool method_provides(const char *name) { + return cipher_get(NULL, name, NULL, NULL); +} + +static size_t method_max_packet_size(fastd_context_t *ctx) { + return (fastd_max_packet_size(ctx) + COMMON_NONCEBYTES + sizeof(fastd_block128_t)); +} + + +static size_t method_min_encrypt_head_space(fastd_context_t *ctx UNUSED) { + return sizeof(fastd_block128_t); +} + +static size_t method_min_decrypt_head_space(fastd_context_t *ctx UNUSED) { + return 0; +} + +static size_t method_min_encrypt_tail_space(fastd_context_t *ctx UNUSED) { + return (sizeof(fastd_block128_t)-1); +} + +static size_t method_min_decrypt_tail_space(fastd_context_t *ctx UNUSED) { + return (2*sizeof(fastd_block128_t)-1); +} + + +static size_t method_key_length(fastd_context_t *ctx UNUSED) { + return sizeof(fastd_block128_t); +} + +static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) { + fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t)); + + fastd_method_common_init(ctx, &session->common, initiator); + + if (!cipher_get(ctx, name, &session->cipher, &session->cipher_ctx)) + exit_bug(ctx, "generic-gcm: can't instanciate cipher"); + + session->cipher_state = session->cipher->init_state(ctx, session->cipher_ctx, secret); + + static const fastd_block128_t zeroblock = {}; + fastd_block128_t H; + + session->cipher->crypt(ctx, session->cipher_state, &H, &zeroblock, sizeof(fastd_block128_t), &zeroblock); + + session->cstate_ghash = ctx->conf->crypto_ghash->set_h(ctx, ctx->crypto_ghash, &H); + + return session; +} + +static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator) { + if (length < sizeof(fastd_block128_t)) + exit_bug(ctx, "generic-gcm: tried to init with short secret"); + + return method_session_init(ctx, name, secret, initiator); +} + +static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) { + return (session && fastd_method_session_common_is_valid(ctx, &session->common)); +} + +static bool method_session_is_initiator(fastd_context_t *ctx UNUSED, fastd_method_session_state_t *session) { + return fastd_method_session_common_is_initiator(&session->common); +} + +static bool method_session_want_refresh(fastd_context_t *ctx, fastd_method_session_state_t *session) { + return fastd_method_session_common_want_refresh(ctx, &session->common); +} + +static void method_session_superseded(fastd_context_t *ctx, fastd_method_session_state_t *session) { + fastd_method_session_common_superseded(ctx, &session->common); +} + +static void method_session_free(fastd_context_t *ctx, fastd_method_session_state_t *session) { + if (session) { + session->cipher->free_state(ctx, session->cipher_state); + ctx->conf->crypto_ghash->free_state(ctx, session->cstate_ghash); + + secure_memzero(session, sizeof(fastd_method_session_state_t)); + free(session); + } +} + +static inline void put_size(fastd_block128_t *out, size_t len) { + memset(out, 0, sizeof(fastd_block128_t)-5); + out->b[sizeof(fastd_block128_t)-5] = len >> 29; + out->b[sizeof(fastd_block128_t)-4] = len >> 21; + out->b[sizeof(fastd_block128_t)-3] = len >> 13; + out->b[sizeof(fastd_block128_t)-2] = len >> 5; + out->b[sizeof(fastd_block128_t)-1] = len << 3; +} + +static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) { + fastd_buffer_pull_head(ctx, &in, sizeof(fastd_block128_t)); + memset(in.data, 0, sizeof(fastd_block128_t)); + + size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len; + *out = fastd_buffer_alloc(ctx, in.len, alignto(COMMON_NONCEBYTES, 16), sizeof(fastd_block128_t)+tail_len); + + if (tail_len) + memset(in.data+in.len, 0, tail_len); + + fastd_block128_t nonce; + memcpy(nonce.b, session->common.send_nonce, COMMON_NONCEBYTES); + memset(nonce.b+COMMON_NONCEBYTES, 0, sizeof(fastd_block128_t)-COMMON_NONCEBYTES-1); + nonce.b[sizeof(fastd_block128_t)-1] = 1; + + int n_blocks = (in.len+sizeof(fastd_block128_t)-1)/sizeof(fastd_block128_t); + + fastd_block128_t *inblocks = in.data; + fastd_block128_t *outblocks = out->data; + fastd_block128_t sig; + + bool ok = session->cipher->crypt(ctx, session->cipher_state, outblocks, inblocks, n_blocks*sizeof(fastd_block128_t), &nonce); + + if (ok) { + if (tail_len) + memset(out->data+out->len, 0, tail_len); + + put_size(&outblocks[n_blocks], in.len-sizeof(fastd_block128_t)); + + ok = ctx->conf->crypto_ghash->hash(ctx, session->cstate_ghash, &sig, outblocks+1, n_blocks); + } + + if (!ok) { + /* restore original buffer */ + fastd_buffer_push_head(ctx, &in, sizeof(fastd_block128_t)); + fastd_buffer_free(*out); + return false; + } + + xor_a(&outblocks[0], &sig); + + fastd_buffer_free(in); + + fastd_buffer_pull_head(ctx, out, COMMON_NONCEBYTES); + memcpy(out->data, session->common.send_nonce, COMMON_NONCEBYTES); + fastd_method_increment_nonce(&session->common); + + return true; +} + +static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) { + if (in.len < COMMON_NONCEBYTES+sizeof(fastd_block128_t)) + return false; + + if (!method_session_is_valid(ctx, session)) + return false; + + fastd_block128_t nonce; + memcpy(nonce.b, in.data, COMMON_NONCEBYTES); + memset(nonce.b+COMMON_NONCEBYTES, 0, sizeof(fastd_block128_t)-COMMON_NONCEBYTES-1); + nonce.b[sizeof(fastd_block128_t)-1] = 1; + + int64_t age; + if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce.b, &age)) + return false; + + fastd_buffer_push_head(ctx, &in, COMMON_NONCEBYTES); + + size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len; + *out = fastd_buffer_alloc(ctx, in.len, 0, tail_len); + + int n_blocks = (in.len+sizeof(fastd_block128_t)-1)/sizeof(fastd_block128_t); + + fastd_block128_t *inblocks = in.data; + fastd_block128_t *outblocks = out->data; + fastd_block128_t sig; + + bool ok = session->cipher->crypt(ctx, session->cipher_state, outblocks, inblocks, n_blocks*sizeof(fastd_block128_t), &nonce); + + if (ok) { + if (tail_len) + memset(in.data+in.len, 0, tail_len); + + put_size(&inblocks[n_blocks], in.len-sizeof(fastd_block128_t)); + + ok = ctx->conf->crypto_ghash->hash(ctx, session->cstate_ghash, &sig, inblocks+1, n_blocks); + } + + if (!ok || memcmp(&sig, &outblocks[0], sizeof(fastd_block128_t)) != 0) { + fastd_buffer_free(*out); + return false; + } + + fastd_buffer_free(in); + + fastd_buffer_push_head(ctx, out, sizeof(fastd_block128_t)); + + if (!fastd_method_reorder_check(ctx, peer, &session->common, nonce.b, age)) { + fastd_buffer_free(*out); + *out = fastd_buffer_alloc(ctx, 0, 0, 0); + } + + return true; +} + +const fastd_method_t fastd_method_generic_gcm = { + .provides = method_provides, + + .max_packet_size = method_max_packet_size, + .min_encrypt_head_space = method_min_encrypt_head_space, + .min_decrypt_head_space = method_min_decrypt_head_space, + .min_encrypt_tail_space = method_min_encrypt_tail_space, + .min_decrypt_tail_space = method_min_decrypt_tail_space, + + .key_length = method_key_length, + .session_init = method_session_init, + .session_init_compat = method_session_init_compat, + .session_is_valid = method_session_is_valid, + .session_is_initiator = method_session_is_initiator, + .session_want_refresh = method_session_want_refresh, + .session_superseded = method_session_superseded, + .session_free = method_session_free, + + .encrypt = method_encrypt, + .decrypt = method_decrypt, +}; 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