| Message ID | 20210201174310.22153-3-arne@rfc2549.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [Openvpn-devel,v3,1/3] Check return values in md_ctx_init and hmac_ctx_init | expand |
Hi, there are some indendation issues still open in this patch. Please see below On 01/02/2021 18:43, Arne Schwabe wrote: > This moves from using our own copy of the TLS1 PRF function to using > TLS library provided function where possible. This includes currently > OpenSSL 1.1.0+ and mbed TLS 2.18+. > > For the libraries where it is not possible to use the library's own > function, we still use our own implementation. mbed TLS will continue > to use our own old PRF function while for OpenSSL we will use a > adapted version from OpenSSL 1.0.2t code. The version allows to be > used in a FIPS enabled environment. > > The old OpenSSL and mbed TLS implementation could have shared some > more code but as we will eventually drop support for older TLS > libraries, the separation makes it easier it remove that code > invdidually. > > In FIPS mode MD5 is normally forbidden, the TLS1 PRF1 function we > use, makes uses of MD5, which in the past has caused OpenVPN to segfault. > The new implementation for OpenSSL version of our custom implementation > has added the special flags that tell OpenSSL that this specific use > of MD5 is allowed in FIPS mode. > > No FIPS conformitiy testing etc has been done, this is only about > allowing OpenVPN on a system where FIPS mode has been enabled system > wide (e.g. on RHEL derivates). > > Signed-off-by: Arne Schwabe <arne@rfc2549.org> > --- > Changes.rst | 10 +- > src/openvpn/crypto_backend.h | 14 +++ > src/openvpn/crypto_mbedtls.c | 134 ++++++++++++++++++++ > src/openvpn/crypto_openssl.c | 165 +++++++++++++++++++++++++ > src/openvpn/ssl.c | 130 +------------------ > tests/unit_tests/openvpn/test_crypto.c | 32 +++++ > 6 files changed, 351 insertions(+), 134 deletions(-) > > diff --git a/Changes.rst b/Changes.rst > index 2a847564..0c66fe2a 100644 > --- a/Changes.rst > +++ b/Changes.rst > @@ -9,11 +9,11 @@ Keying Material Exporters (RFC 5705) based key generation > the RFC5705 based key material generation to the current custom > OpenVPN PRF. This feature requires OpenSSL or mbed TLS 2.18+. > > -Deprecated features > -------------------- > -``inetd`` has been removed > - This was a very limited and not-well-tested way to run OpenVPN, on TCP > - and TAP mode only. > +Compatibility with OpenSSL in FIPS mode > + OpenVPN will now work with OpenSSL in FIPS mode. Note, no effort > + has been made to check or implement all the > + requirements/recommendation of FIPS 140-2. This just allows OpenVPN > + to be run on a system that be configured OpenSSL in FIPS mode. > > > Overview of changes in 2.5 > diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h > index 85cb084a..d86d9a34 100644 > --- a/src/openvpn/crypto_backend.h > +++ b/src/openvpn/crypto_backend.h > @@ -699,4 +699,18 @@ const char *translate_cipher_name_from_openvpn(const char *cipher_name); > */ > const char *translate_cipher_name_to_openvpn(const char *cipher_name); > > + > +/** > + * Calculates the TLS 1.0-1.1 PRF function. For the exact specification of the > + * function definition see the TLS RFCs like RFC 4346. > + * > + * @param seed seed to use > + * @param seed_len length of the seed > + * @param secret secret to use > + * @param secret_len length of the secret > + * @param output output destination > + * @param output_len length of output/number of bytes to generate > + */ > +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, > + int secret_len, uint8_t *output, int output_len); > #endif /* CRYPTO_BACKEND_H_ */ > diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c > index fbb1f120..5ed88d6d 100644 > --- a/src/openvpn/crypto_mbedtls.c > +++ b/src/openvpn/crypto_mbedtls.c > @@ -54,6 +54,7 @@ > #include <mbedtls/pem.h> > > #include <mbedtls/entropy.h> > +#include <mbedtls/ssl.h> > > > /* > @@ -984,4 +985,137 @@ memcmp_constant_time(const void *a, const void *b, size_t size) > > return diff; > } > +/* mbedtls-2.18.0 or newer */ > +#ifdef HAVE_MBEDTLS_SSL_TLS_PRF > +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, > + int secret_len, uint8_t *output, int output_len) > +{ > + mbedtls_ssl_tls_prf(MBEDTLS_SSL_TLS_PRF_TLS1, secret, secret_len, "", seed, > + seed_len, output, output_len); > +} > +#else > +/* > + * Generate the hash required by for the \c tls1_PRF function. > + * > + * @param md_kt Message digest to use > + * @param sec Secret to base the hash on > + * @param sec_len Length of the secret > + * @param seed Seed to hash > + * @param seed_len Length of the seed > + * @param out Output buffer > + * @param olen Length of the output buffer > + */ > +static void > +tls1_P_hash(const md_kt_t *md_kt, > + const uint8_t *sec, > + int sec_len, > + const uint8_t *seed, > + int seed_len, > + uint8_t *out, > + int olen) This should be reindented > +{ > + struct gc_arena gc = gc_new(); > + uint8_t A1[MAX_HMAC_KEY_LENGTH]; > + > +#ifdef ENABLE_DEBUG > + const int olen_orig = olen; > + const uint8_t *out_orig = out; > +#endif > + > + hmac_ctx_t *ctx = hmac_ctx_new(); > + hmac_ctx_t *ctx_tmp = hmac_ctx_new(); > + > + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex(sec, sec_len, 0, &gc)); > + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex(seed, seed_len, 0, &gc)); > + > + int chunk = md_kt_size(md_kt); > + unsigned int A1_len = md_kt_size(md_kt); > + > + hmac_ctx_init(ctx, sec, sec_len, md_kt); > + hmac_ctx_init(ctx_tmp, sec, sec_len, md_kt); > + > + hmac_ctx_update(ctx,seed,seed_len); > + hmac_ctx_final(ctx, A1); > + > + for (;;) > + { > + hmac_ctx_reset(ctx); > + hmac_ctx_reset(ctx_tmp); > + hmac_ctx_update(ctx, A1, A1_len); > + hmac_ctx_update(ctx_tmp, A1, A1_len); > + hmac_ctx_update(ctx, seed, seed_len); > + > + if (olen > chunk) > + { > + hmac_ctx_final(ctx, out); > + out += chunk; > + olen -= chunk; > + hmac_ctx_final(ctx_tmp, A1); /* calc the next A1 value */ > + } > + else /* last one */ > + { > + hmac_ctx_final(ctx, A1); > + memcpy(out, A1, olen); > + break; > + } > + } > + hmac_ctx_cleanup(ctx); > + hmac_ctx_free(ctx); > + hmac_ctx_cleanup(ctx_tmp); > + hmac_ctx_free(ctx_tmp); > + secure_memzero(A1, sizeof(A1)); > + > + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex(out_orig, olen_orig, 0, &gc)); > + gc_free(&gc); > +} > + > +/* > + * Use the TLS PRF function for generating data channel keys. > + * This code is based on the OpenSSL library. > + * > + * TLS generates keys as such: > + * > + * master_secret[48] = PRF(pre_master_secret[48], "master secret", > + * ClientHello.random[32] + ServerHello.random[32]) > + * > + * key_block[] = PRF(SecurityParameters.master_secret[48], > + * "key expansion", > + * SecurityParameters.server_random[32] + > + * SecurityParameters.client_random[32]); > + * > + * Notes: > + * > + * (1) key_block contains a full set of 4 keys. > + * (2) The pre-master secret is generated by the client. > + */ > +void > +ssl_tls1_PRF(const uint8_t *label, int label_len, const uint8_t *sec, int slen, > + uint8_t *out1, int olen) indentation seems off (?) > +{ > + struct gc_arena gc = gc_new(); > + const md_kt_t *md5 = md_kt_get("MD5"); > + const md_kt_t *sha1 = md_kt_get("SHA1"); > + > + uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); remove space after cast > + > + int len = slen/2; > + const uint8_t *S1 = sec; > + const uint8_t *S2 = &(sec[len]); > + len += (slen&1); /* add for odd, make longer */ > + > + tls1_P_hash(md5,S1,len,label,label_len,out1,olen); > + tls1_P_hash(sha1,S2,len,label,label_len,out2,olen); > + > + for (int i = 0; i<olen; i++) > + { > + out1[i] ^= out2[i]; > + } > + > + secure_memzero(out2, olen); > + > + dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); > + > + gc_free(&gc); > +} > +#endif > #endif /* ENABLE_CRYPTO_MBEDTLS */ > diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c > index e124a7b6..b42dc044 100644 > --- a/src/openvpn/crypto_openssl.c > +++ b/src/openvpn/crypto_openssl.c > @@ -50,6 +50,9 @@ > #include <openssl/objects.h> > #include <openssl/rand.h> > #include <openssl/ssl.h> > +#if OPENSSL_VERSION_NUMBER >= 0x10100000L > +#include <openssl/kdf.h> > +#endif > > /* > * Check for key size creepage. > @@ -1124,4 +1127,166 @@ engine_load_key(const char *file, SSL_CTX *ctx) > #endif /* if HAVE_OPENSSL_ENGINE */ > } > > +#if OPENSSL_VERSION_NUMBER >= 0x10100000L > +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, > + int secret_len, uint8_t *output, int output_len) > +{ > + EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_TLS1_PRF, NULL); > + ASSERT(EVP_PKEY_derive_init(pctx) == 1); > + > + ASSERT(EVP_PKEY_CTX_set_tls1_prf_md(pctx, EVP_md5_sha1()) == 1); > + > + ASSERT(EVP_PKEY_CTX_set1_tls1_prf_secret(pctx, secret, secret_len) == 1); > + > + ASSERT(EVP_PKEY_CTX_add1_tls1_prf_seed(pctx, seed, seed_len) == 1); > + > + size_t out_len = output_len; > + ASSERT (EVP_PKEY_derive(pctx, output, &out_len) == 1); > + ASSERT (out_len == output_len); > +} > +#else > +/* > + * Generate the hash required by for the \c tls1_PRF function. > + * > + * We cannot use our normal hmac_* function as they do not work > + * in a FIPS environment (no MD5 allowed, which we need). Instead > + * we need to directly use the EVP_MD_* API with the special > + * EVP_MD_CTX_FLAG_NON_FIPS_ALLOW flag. > + * > + * > + * The function below is adapted from OpenSSL 1.0.2t > + * > + * @param md_kt Message digest to use > + * @param sec Secret to base the hash on > + * @param sec_len Length of the secret > + * @param seed Seed to hash > + * @param seed_len Length of the seed > + * @param out Output buffer > + * @param olen Length of the output buffer > + */ > +static > +int tls1_P_hash(const EVP_MD *md, const unsigned char *sec, > + int sec_len, > + const void *seed, int seed_len, > + unsigned char *out, int olen) This should be reindented > +{ > + int chunk; > + size_t j; > + EVP_MD_CTX ctx, ctx_tmp, ctx_init; > + EVP_PKEY *mac_key; > + unsigned char A1[EVP_MAX_MD_SIZE]; > + size_t A1_len; > + int ret = 0; > + > + chunk = EVP_MD_size(md); > + OPENSSL_assert(chunk >= 0); > + > + EVP_MD_CTX_init(&ctx); > + EVP_MD_CTX_init(&ctx_tmp); > + EVP_MD_CTX_init(&ctx_init); > + EVP_MD_CTX_set_flags(&ctx_init, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW); > + mac_key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, sec, sec_len); > + if (!mac_key) > + goto err; > + if (!EVP_DigestSignInit(&ctx_init, NULL, md, NULL, mac_key)) > + goto err; > + if (!EVP_MD_CTX_copy_ex(&ctx, &ctx_init)) > + goto err; > + if (!EVP_DigestSignUpdate(&ctx, seed, seed_len)) > + goto err; > + if (!EVP_DigestSignFinal(&ctx, A1, &A1_len)) > + goto err; > + > + for (;;) { > + /* Reinit mac contexts */ > + if (!EVP_MD_CTX_copy_ex(&ctx, &ctx_init)) > + goto err; > + if (!EVP_DigestSignUpdate(&ctx, A1, A1_len)) > + goto err; > + if (olen > chunk && !EVP_MD_CTX_copy_ex(&ctx_tmp, &ctx)) > + goto err; > + if (!EVP_DigestSignUpdate(&ctx, seed, seed_len)) > + goto err; > + > + if (olen > chunk) > + { > + if (!EVP_DigestSignFinal(&ctx, out, &j)) > + goto err; > + out += j; > + olen -= j; > + /* calc the next A1 value */ > + if (!EVP_DigestSignFinal(&ctx_tmp, A1, &A1_len)) > + goto err; > + } > + else > + { > + /* last one */ > + > + if (!EVP_DigestSignFinal(&ctx, A1, &A1_len)) > + goto err; > + memcpy(out, A1, olen); > + break; > + } > + } > + ret = 1; > +err: > + EVP_PKEY_free(mac_key); > + EVP_MD_CTX_cleanup(&ctx); > + EVP_MD_CTX_cleanup(&ctx_tmp); > + EVP_MD_CTX_cleanup(&ctx_init); > + OPENSSL_cleanse(A1, sizeof(A1)); > + return ret; > +} > + > + > +/* > + * Use the TLS PRF function for generating data channel keys. > + * This code is based on the OpenSSL library. > + * > + * TLS generates keys as such: > + * > + * master_secret[48] = PRF(pre_master_secret[48], "master secret", > + * ClientHello.random[32] + ServerHello.random[32]) > + * > + * key_block[] = PRF(SecurityParameters.master_secret[48], > + * "key expansion", > + * SecurityParameters.server_random[32] + > + * SecurityParameters.client_random[32]); > + * > + * Notes: > + * > + * (1) key_block contains a full set of 4 keys. > + * (2) The pre-master secret is generated by the client. > + */ > +void ssl_tls1_PRF(const uint8_t *label, int label_len, const uint8_t *sec, > + int slen, uint8_t *out1, int olen) > +{ > + struct gc_arena gc = gc_new(); > + /* For some reason our md_kt_get("MD5") fails otherwise in the unit test */ > + const md_kt_t *md5 = EVP_md5(); > + const md_kt_t *sha1 = EVP_sha1(); > + > + uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); > + > + int len = slen/2; > + const uint8_t *S1 = sec; > + const uint8_t *S2 = &(sec[len]); > + len += (slen&1); /* add for odd, make longer */ > + > + if(!tls1_P_hash(md5,S1,len,label,label_len,out1,olen)) > + > + ASSERT(tls1_P_hash(sha1,S2,len,label,label_len,out2,olen)); > + > + for (int i = 0; i<olen; i++) > + { > + out1[i] ^= out2[i]; > + } > + > + secure_memzero(out2, olen); > + > + dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); > + > + gc_free(&gc); > +} > +#endif > #endif /* ENABLE_CRYPTO_OPENSSL */ > diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c > index efbf688f..c0de76b5 100644 > --- a/src/openvpn/ssl.c > +++ b/src/openvpn/ssl.c > @@ -1580,134 +1580,6 @@ key_source2_print(const struct key_source2 *k) > key_source_print(&k->server, "Server"); > } > > -/* > - * Generate the hash required by for the \c tls1_PRF function. > - * > - * @param md_kt Message digest to use > - * @param sec Secret to base the hash on > - * @param sec_len Length of the secret > - * @param seed Seed to hash > - * @param seed_len Length of the seed > - * @param out Output buffer > - * @param olen Length of the output buffer > - */ > -static void > -tls1_P_hash(const md_kt_t *md_kt, > - const uint8_t *sec, > - int sec_len, > - const uint8_t *seed, > - int seed_len, > - uint8_t *out, > - int olen) > -{ > - struct gc_arena gc = gc_new(); > - uint8_t A1[MAX_HMAC_KEY_LENGTH]; > - > -#ifdef ENABLE_DEBUG > - const int olen_orig = olen; > - const uint8_t *out_orig = out; > -#endif > - > - hmac_ctx_t *ctx = hmac_ctx_new(); > - hmac_ctx_t *ctx_tmp = hmac_ctx_new(); > - > - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex(sec, sec_len, 0, &gc)); > - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex(seed, seed_len, 0, &gc)); > - > - int chunk = md_kt_size(md_kt); > - unsigned int A1_len = md_kt_size(md_kt); > - > - hmac_ctx_init(ctx, sec, sec_len, md_kt); > - hmac_ctx_init(ctx_tmp, sec, sec_len, md_kt); > - > - hmac_ctx_update(ctx,seed,seed_len); > - hmac_ctx_final(ctx, A1); > - > - for (;; ) > - { > - hmac_ctx_reset(ctx); > - hmac_ctx_reset(ctx_tmp); > - hmac_ctx_update(ctx,A1,A1_len); > - hmac_ctx_update(ctx_tmp,A1,A1_len); > - hmac_ctx_update(ctx,seed,seed_len); > - > - if (olen > chunk) > - { > - hmac_ctx_final(ctx, out); > - out += chunk; > - olen -= chunk; > - hmac_ctx_final(ctx_tmp, A1); /* calc the next A1 value */ > - } > - else /* last one */ > - { > - hmac_ctx_final(ctx, A1); > - memcpy(out,A1,olen); > - break; > - } > - } > - hmac_ctx_cleanup(ctx); > - hmac_ctx_free(ctx); > - hmac_ctx_cleanup(ctx_tmp); > - hmac_ctx_free(ctx_tmp); > - secure_memzero(A1, sizeof(A1)); > - > - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex(out_orig, olen_orig, 0, &gc)); > - gc_free(&gc); > -} > - > -/* > - * Use the TLS PRF function for generating data channel keys. > - * This code is based on the OpenSSL library. > - * > - * TLS generates keys as such: > - * > - * master_secret[48] = PRF(pre_master_secret[48], "master secret", > - * ClientHello.random[32] + ServerHello.random[32]) > - * > - * key_block[] = PRF(SecurityParameters.master_secret[48], > - * "key expansion", > - * SecurityParameters.server_random[32] + > - * SecurityParameters.client_random[32]); > - * > - * Notes: > - * > - * (1) key_block contains a full set of 4 keys. > - * (2) The pre-master secret is generated by the client. > - */ > -static void > -tls1_PRF(const uint8_t *label, > - int label_len, > - const uint8_t *sec, > - int slen, > - uint8_t *out1, > - int olen) > -{ > - struct gc_arena gc = gc_new(); > - const md_kt_t *md5 = md_kt_get("MD5"); > - const md_kt_t *sha1 = md_kt_get("SHA1"); > - > - uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); > - > - int len = slen/2; > - const uint8_t *S1 = sec; > - const uint8_t *S2 = &(sec[len]); > - len += (slen&1); /* add for odd, make longer */ > - > - tls1_P_hash(md5,S1,len,label,label_len,out1,olen); > - tls1_P_hash(sha1,S2,len,label,label_len,out2,olen); > - > - for (int i = 0; i<olen; i++) > - { > - out1[i] ^= out2[i]; > - } > - > - secure_memzero(out2, olen); > - > - dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); > - > - gc_free(&gc); > -} > - > static void > openvpn_PRF(const uint8_t *secret, > int secret_len, > @@ -1742,7 +1614,7 @@ openvpn_PRF(const uint8_t *secret, > } > > /* compute PRF */ > - tls1_PRF(BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len); > + ssl_tls1_PRF(BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len); > > buf_clear(&seed); > free_buf(&seed); > diff --git a/tests/unit_tests/openvpn/test_crypto.c b/tests/unit_tests/openvpn/test_crypto.c > index ea9b99b2..6c68099e 100644 > --- a/tests/unit_tests/openvpn/test_crypto.c > +++ b/tests/unit_tests/openvpn/test_crypto.c > @@ -38,6 +38,7 @@ > #include <cmocka.h> > > #include "crypto.h" > +#include "ssl_backend.h" > > #include "mock_msg.h" > > @@ -136,12 +137,43 @@ crypto_translate_cipher_names(void **state) > test_cipher_names("id-aes256-GCM", "AES-256-GCM"); > } > > + > +static uint8_t good_prf[32] = {0xd9, 0x8c, 0x85, 0x18, 0xc8, 0x5e, 0x94, 0x69, > + 0x27, 0x91, 0x6a, 0xcf, 0xc2, 0xd5, 0x92, 0xfb, > + 0xb1, 0x56, 0x7e, 0x4b, 0x4b, 0x14, 0x59, 0xe6, > + 0xa9, 0x04, 0xac, 0x2d, 0xda, 0xb7, 0x2d, 0x67}; > +static void > +crypto_test_tls_prf(void **state) > +{ > + const char *seedstr = "Quis aute iure reprehenderit in voluptate " > + "velit esse cillum dolore"; > + const unsigned char *seed = (const unsigned char *) seedstr; no space after cast > + const size_t seed_len = strlen(seedstr); > + > + > + > + > + const char* ipsumlorem = "Lorem ipsum dolor sit amet, consectetur " > + "adipisici elit, sed eiusmod tempor incidunt ut " > + "labore et dolore magna aliqua."; > + > + const unsigned char *secret = (const unsigned char *) ipsumlorem; > + size_t secret_len = strlen((const char *)secret); > + > + > + uint8_t out[32]; > + ssl_tls1_PRF(seed, seed_len, secret, secret_len, out, sizeof(out)); > + > + assert_memory_equal(good_prf, out, sizeof(out)); > +} > + > int > main(void) > { > const struct CMUnitTest tests[] = { > cmocka_unit_test(crypto_pem_encode_decode_loopback), > cmocka_unit_test(crypto_translate_cipher_names), > + cmocka_unit_test(crypto_test_tls_prf) > }; > > #if defined(ENABLE_CRYPTO_OPENSSL) > Cheers,
diff --git a/Changes.rst b/Changes.rst index 2a847564..0c66fe2a 100644 --- a/Changes.rst +++ b/Changes.rst @@ -9,11 +9,11 @@ Keying Material Exporters (RFC 5705) based key generation the RFC5705 based key material generation to the current custom OpenVPN PRF. This feature requires OpenSSL or mbed TLS 2.18+. -Deprecated features -------------------- -``inetd`` has been removed - This was a very limited and not-well-tested way to run OpenVPN, on TCP - and TAP mode only. +Compatibility with OpenSSL in FIPS mode + OpenVPN will now work with OpenSSL in FIPS mode. Note, no effort + has been made to check or implement all the + requirements/recommendation of FIPS 140-2. This just allows OpenVPN + to be run on a system that be configured OpenSSL in FIPS mode. Overview of changes in 2.5 diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h index 85cb084a..d86d9a34 100644 --- a/src/openvpn/crypto_backend.h +++ b/src/openvpn/crypto_backend.h @@ -699,4 +699,18 @@ const char *translate_cipher_name_from_openvpn(const char *cipher_name); */ const char *translate_cipher_name_to_openvpn(const char *cipher_name); + +/** + * Calculates the TLS 1.0-1.1 PRF function. For the exact specification of the + * function definition see the TLS RFCs like RFC 4346. + * + * @param seed seed to use + * @param seed_len length of the seed + * @param secret secret to use + * @param secret_len length of the secret + * @param output output destination + * @param output_len length of output/number of bytes to generate + */ +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, + int secret_len, uint8_t *output, int output_len); #endif /* CRYPTO_BACKEND_H_ */ diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c index fbb1f120..5ed88d6d 100644 --- a/src/openvpn/crypto_mbedtls.c +++ b/src/openvpn/crypto_mbedtls.c @@ -54,6 +54,7 @@ #include <mbedtls/pem.h> #include <mbedtls/entropy.h> +#include <mbedtls/ssl.h> /* @@ -984,4 +985,137 @@ memcmp_constant_time(const void *a, const void *b, size_t size) return diff; } +/* mbedtls-2.18.0 or newer */ +#ifdef HAVE_MBEDTLS_SSL_TLS_PRF +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, + int secret_len, uint8_t *output, int output_len) +{ + mbedtls_ssl_tls_prf(MBEDTLS_SSL_TLS_PRF_TLS1, secret, secret_len, "", seed, + seed_len, output, output_len); +} +#else +/* + * Generate the hash required by for the \c tls1_PRF function. + * + * @param md_kt Message digest to use + * @param sec Secret to base the hash on + * @param sec_len Length of the secret + * @param seed Seed to hash + * @param seed_len Length of the seed + * @param out Output buffer + * @param olen Length of the output buffer + */ +static void +tls1_P_hash(const md_kt_t *md_kt, + const uint8_t *sec, + int sec_len, + const uint8_t *seed, + int seed_len, + uint8_t *out, + int olen) +{ + struct gc_arena gc = gc_new(); + uint8_t A1[MAX_HMAC_KEY_LENGTH]; + +#ifdef ENABLE_DEBUG + const int olen_orig = olen; + const uint8_t *out_orig = out; +#endif + + hmac_ctx_t *ctx = hmac_ctx_new(); + hmac_ctx_t *ctx_tmp = hmac_ctx_new(); + + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex(sec, sec_len, 0, &gc)); + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex(seed, seed_len, 0, &gc)); + + int chunk = md_kt_size(md_kt); + unsigned int A1_len = md_kt_size(md_kt); + + hmac_ctx_init(ctx, sec, sec_len, md_kt); + hmac_ctx_init(ctx_tmp, sec, sec_len, md_kt); + + hmac_ctx_update(ctx,seed,seed_len); + hmac_ctx_final(ctx, A1); + + for (;;) + { + hmac_ctx_reset(ctx); + hmac_ctx_reset(ctx_tmp); + hmac_ctx_update(ctx, A1, A1_len); + hmac_ctx_update(ctx_tmp, A1, A1_len); + hmac_ctx_update(ctx, seed, seed_len); + + if (olen > chunk) + { + hmac_ctx_final(ctx, out); + out += chunk; + olen -= chunk; + hmac_ctx_final(ctx_tmp, A1); /* calc the next A1 value */ + } + else /* last one */ + { + hmac_ctx_final(ctx, A1); + memcpy(out, A1, olen); + break; + } + } + hmac_ctx_cleanup(ctx); + hmac_ctx_free(ctx); + hmac_ctx_cleanup(ctx_tmp); + hmac_ctx_free(ctx_tmp); + secure_memzero(A1, sizeof(A1)); + + dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex(out_orig, olen_orig, 0, &gc)); + gc_free(&gc); +} + +/* + * Use the TLS PRF function for generating data channel keys. + * This code is based on the OpenSSL library. + * + * TLS generates keys as such: + * + * master_secret[48] = PRF(pre_master_secret[48], "master secret", + * ClientHello.random[32] + ServerHello.random[32]) + * + * key_block[] = PRF(SecurityParameters.master_secret[48], + * "key expansion", + * SecurityParameters.server_random[32] + + * SecurityParameters.client_random[32]); + * + * Notes: + * + * (1) key_block contains a full set of 4 keys. + * (2) The pre-master secret is generated by the client. + */ +void +ssl_tls1_PRF(const uint8_t *label, int label_len, const uint8_t *sec, int slen, + uint8_t *out1, int olen) +{ + struct gc_arena gc = gc_new(); + const md_kt_t *md5 = md_kt_get("MD5"); + const md_kt_t *sha1 = md_kt_get("SHA1"); + + uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); + + int len = slen/2; + const uint8_t *S1 = sec; + const uint8_t *S2 = &(sec[len]); + len += (slen&1); /* add for odd, make longer */ + + tls1_P_hash(md5,S1,len,label,label_len,out1,olen); + tls1_P_hash(sha1,S2,len,label,label_len,out2,olen); + + for (int i = 0; i<olen; i++) + { + out1[i] ^= out2[i]; + } + + secure_memzero(out2, olen); + + dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); + + gc_free(&gc); +} +#endif #endif /* ENABLE_CRYPTO_MBEDTLS */ diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c index e124a7b6..b42dc044 100644 --- a/src/openvpn/crypto_openssl.c +++ b/src/openvpn/crypto_openssl.c @@ -50,6 +50,9 @@ #include <openssl/objects.h> #include <openssl/rand.h> #include <openssl/ssl.h> +#if OPENSSL_VERSION_NUMBER >= 0x10100000L +#include <openssl/kdf.h> +#endif /* * Check for key size creepage. @@ -1124,4 +1127,166 @@ engine_load_key(const char *file, SSL_CTX *ctx) #endif /* if HAVE_OPENSSL_ENGINE */ } +#if OPENSSL_VERSION_NUMBER >= 0x10100000L +void ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret, + int secret_len, uint8_t *output, int output_len) +{ + EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_TLS1_PRF, NULL); + ASSERT(EVP_PKEY_derive_init(pctx) == 1); + + ASSERT(EVP_PKEY_CTX_set_tls1_prf_md(pctx, EVP_md5_sha1()) == 1); + + ASSERT(EVP_PKEY_CTX_set1_tls1_prf_secret(pctx, secret, secret_len) == 1); + + ASSERT(EVP_PKEY_CTX_add1_tls1_prf_seed(pctx, seed, seed_len) == 1); + + size_t out_len = output_len; + ASSERT (EVP_PKEY_derive(pctx, output, &out_len) == 1); + ASSERT (out_len == output_len); +} +#else +/* + * Generate the hash required by for the \c tls1_PRF function. + * + * We cannot use our normal hmac_* function as they do not work + * in a FIPS environment (no MD5 allowed, which we need). Instead + * we need to directly use the EVP_MD_* API with the special + * EVP_MD_CTX_FLAG_NON_FIPS_ALLOW flag. + * + * + * The function below is adapted from OpenSSL 1.0.2t + * + * @param md_kt Message digest to use + * @param sec Secret to base the hash on + * @param sec_len Length of the secret + * @param seed Seed to hash + * @param seed_len Length of the seed + * @param out Output buffer + * @param olen Length of the output buffer + */ +static +int tls1_P_hash(const EVP_MD *md, const unsigned char *sec, + int sec_len, + const void *seed, int seed_len, + unsigned char *out, int olen) +{ + int chunk; + size_t j; + EVP_MD_CTX ctx, ctx_tmp, ctx_init; + EVP_PKEY *mac_key; + unsigned char A1[EVP_MAX_MD_SIZE]; + size_t A1_len; + int ret = 0; + + chunk = EVP_MD_size(md); + OPENSSL_assert(chunk >= 0); + + EVP_MD_CTX_init(&ctx); + EVP_MD_CTX_init(&ctx_tmp); + EVP_MD_CTX_init(&ctx_init); + EVP_MD_CTX_set_flags(&ctx_init, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW); + mac_key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, sec, sec_len); + if (!mac_key) + goto err; + if (!EVP_DigestSignInit(&ctx_init, NULL, md, NULL, mac_key)) + goto err; + if (!EVP_MD_CTX_copy_ex(&ctx, &ctx_init)) + goto err; + if (!EVP_DigestSignUpdate(&ctx, seed, seed_len)) + goto err; + if (!EVP_DigestSignFinal(&ctx, A1, &A1_len)) + goto err; + + for (;;) { + /* Reinit mac contexts */ + if (!EVP_MD_CTX_copy_ex(&ctx, &ctx_init)) + goto err; + if (!EVP_DigestSignUpdate(&ctx, A1, A1_len)) + goto err; + if (olen > chunk && !EVP_MD_CTX_copy_ex(&ctx_tmp, &ctx)) + goto err; + if (!EVP_DigestSignUpdate(&ctx, seed, seed_len)) + goto err; + + if (olen > chunk) + { + if (!EVP_DigestSignFinal(&ctx, out, &j)) + goto err; + out += j; + olen -= j; + /* calc the next A1 value */ + if (!EVP_DigestSignFinal(&ctx_tmp, A1, &A1_len)) + goto err; + } + else + { + /* last one */ + + if (!EVP_DigestSignFinal(&ctx, A1, &A1_len)) + goto err; + memcpy(out, A1, olen); + break; + } + } + ret = 1; +err: + EVP_PKEY_free(mac_key); + EVP_MD_CTX_cleanup(&ctx); + EVP_MD_CTX_cleanup(&ctx_tmp); + EVP_MD_CTX_cleanup(&ctx_init); + OPENSSL_cleanse(A1, sizeof(A1)); + return ret; +} + + +/* + * Use the TLS PRF function for generating data channel keys. + * This code is based on the OpenSSL library. + * + * TLS generates keys as such: + * + * master_secret[48] = PRF(pre_master_secret[48], "master secret", + * ClientHello.random[32] + ServerHello.random[32]) + * + * key_block[] = PRF(SecurityParameters.master_secret[48], + * "key expansion", + * SecurityParameters.server_random[32] + + * SecurityParameters.client_random[32]); + * + * Notes: + * + * (1) key_block contains a full set of 4 keys. + * (2) The pre-master secret is generated by the client. + */ +void ssl_tls1_PRF(const uint8_t *label, int label_len, const uint8_t *sec, + int slen, uint8_t *out1, int olen) +{ + struct gc_arena gc = gc_new(); + /* For some reason our md_kt_get("MD5") fails otherwise in the unit test */ + const md_kt_t *md5 = EVP_md5(); + const md_kt_t *sha1 = EVP_sha1(); + + uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); + + int len = slen/2; + const uint8_t *S1 = sec; + const uint8_t *S2 = &(sec[len]); + len += (slen&1); /* add for odd, make longer */ + + if(!tls1_P_hash(md5,S1,len,label,label_len,out1,olen)) + + ASSERT(tls1_P_hash(sha1,S2,len,label,label_len,out2,olen)); + + for (int i = 0; i<olen; i++) + { + out1[i] ^= out2[i]; + } + + secure_memzero(out2, olen); + + dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); + + gc_free(&gc); +} +#endif #endif /* ENABLE_CRYPTO_OPENSSL */ diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index efbf688f..c0de76b5 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -1580,134 +1580,6 @@ key_source2_print(const struct key_source2 *k) key_source_print(&k->server, "Server"); } -/* - * Generate the hash required by for the \c tls1_PRF function. - * - * @param md_kt Message digest to use - * @param sec Secret to base the hash on - * @param sec_len Length of the secret - * @param seed Seed to hash - * @param seed_len Length of the seed - * @param out Output buffer - * @param olen Length of the output buffer - */ -static void -tls1_P_hash(const md_kt_t *md_kt, - const uint8_t *sec, - int sec_len, - const uint8_t *seed, - int seed_len, - uint8_t *out, - int olen) -{ - struct gc_arena gc = gc_new(); - uint8_t A1[MAX_HMAC_KEY_LENGTH]; - -#ifdef ENABLE_DEBUG - const int olen_orig = olen; - const uint8_t *out_orig = out; -#endif - - hmac_ctx_t *ctx = hmac_ctx_new(); - hmac_ctx_t *ctx_tmp = hmac_ctx_new(); - - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex(sec, sec_len, 0, &gc)); - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex(seed, seed_len, 0, &gc)); - - int chunk = md_kt_size(md_kt); - unsigned int A1_len = md_kt_size(md_kt); - - hmac_ctx_init(ctx, sec, sec_len, md_kt); - hmac_ctx_init(ctx_tmp, sec, sec_len, md_kt); - - hmac_ctx_update(ctx,seed,seed_len); - hmac_ctx_final(ctx, A1); - - for (;; ) - { - hmac_ctx_reset(ctx); - hmac_ctx_reset(ctx_tmp); - hmac_ctx_update(ctx,A1,A1_len); - hmac_ctx_update(ctx_tmp,A1,A1_len); - hmac_ctx_update(ctx,seed,seed_len); - - if (olen > chunk) - { - hmac_ctx_final(ctx, out); - out += chunk; - olen -= chunk; - hmac_ctx_final(ctx_tmp, A1); /* calc the next A1 value */ - } - else /* last one */ - { - hmac_ctx_final(ctx, A1); - memcpy(out,A1,olen); - break; - } - } - hmac_ctx_cleanup(ctx); - hmac_ctx_free(ctx); - hmac_ctx_cleanup(ctx_tmp); - hmac_ctx_free(ctx_tmp); - secure_memzero(A1, sizeof(A1)); - - dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex(out_orig, olen_orig, 0, &gc)); - gc_free(&gc); -} - -/* - * Use the TLS PRF function for generating data channel keys. - * This code is based on the OpenSSL library. - * - * TLS generates keys as such: - * - * master_secret[48] = PRF(pre_master_secret[48], "master secret", - * ClientHello.random[32] + ServerHello.random[32]) - * - * key_block[] = PRF(SecurityParameters.master_secret[48], - * "key expansion", - * SecurityParameters.server_random[32] + - * SecurityParameters.client_random[32]); - * - * Notes: - * - * (1) key_block contains a full set of 4 keys. - * (2) The pre-master secret is generated by the client. - */ -static void -tls1_PRF(const uint8_t *label, - int label_len, - const uint8_t *sec, - int slen, - uint8_t *out1, - int olen) -{ - struct gc_arena gc = gc_new(); - const md_kt_t *md5 = md_kt_get("MD5"); - const md_kt_t *sha1 = md_kt_get("SHA1"); - - uint8_t *out2 = (uint8_t *) gc_malloc(olen, false, &gc); - - int len = slen/2; - const uint8_t *S1 = sec; - const uint8_t *S2 = &(sec[len]); - len += (slen&1); /* add for odd, make longer */ - - tls1_P_hash(md5,S1,len,label,label_len,out1,olen); - tls1_P_hash(sha1,S2,len,label,label_len,out2,olen); - - for (int i = 0; i<olen; i++) - { - out1[i] ^= out2[i]; - } - - secure_memzero(out2, olen); - - dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc)); - - gc_free(&gc); -} - static void openvpn_PRF(const uint8_t *secret, int secret_len, @@ -1742,7 +1614,7 @@ openvpn_PRF(const uint8_t *secret, } /* compute PRF */ - tls1_PRF(BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len); + ssl_tls1_PRF(BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len); buf_clear(&seed); free_buf(&seed); diff --git a/tests/unit_tests/openvpn/test_crypto.c b/tests/unit_tests/openvpn/test_crypto.c index ea9b99b2..6c68099e 100644 --- a/tests/unit_tests/openvpn/test_crypto.c +++ b/tests/unit_tests/openvpn/test_crypto.c @@ -38,6 +38,7 @@ #include <cmocka.h> #include "crypto.h" +#include "ssl_backend.h" #include "mock_msg.h" @@ -136,12 +137,43 @@ crypto_translate_cipher_names(void **state) test_cipher_names("id-aes256-GCM", "AES-256-GCM"); } + +static uint8_t good_prf[32] = {0xd9, 0x8c, 0x85, 0x18, 0xc8, 0x5e, 0x94, 0x69, + 0x27, 0x91, 0x6a, 0xcf, 0xc2, 0xd5, 0x92, 0xfb, + 0xb1, 0x56, 0x7e, 0x4b, 0x4b, 0x14, 0x59, 0xe6, + 0xa9, 0x04, 0xac, 0x2d, 0xda, 0xb7, 0x2d, 0x67}; +static void +crypto_test_tls_prf(void **state) +{ + const char *seedstr = "Quis aute iure reprehenderit in voluptate " + "velit esse cillum dolore"; + const unsigned char *seed = (const unsigned char *) seedstr; + const size_t seed_len = strlen(seedstr); + + + + + const char* ipsumlorem = "Lorem ipsum dolor sit amet, consectetur " + "adipisici elit, sed eiusmod tempor incidunt ut " + "labore et dolore magna aliqua."; + + const unsigned char *secret = (const unsigned char *) ipsumlorem; + size_t secret_len = strlen((const char *)secret); + + + uint8_t out[32]; + ssl_tls1_PRF(seed, seed_len, secret, secret_len, out, sizeof(out)); + + assert_memory_equal(good_prf, out, sizeof(out)); +} + int main(void) { const struct CMUnitTest tests[] = { cmocka_unit_test(crypto_pem_encode_decode_loopback), cmocka_unit_test(crypto_translate_cipher_names), + cmocka_unit_test(crypto_test_tls_prf) }; #if defined(ENABLE_CRYPTO_OPENSSL)
This moves from using our own copy of the TLS1 PRF function to using TLS library provided function where possible. This includes currently OpenSSL 1.1.0+ and mbed TLS 2.18+. For the libraries where it is not possible to use the library's own function, we still use our own implementation. mbed TLS will continue to use our own old PRF function while for OpenSSL we will use a adapted version from OpenSSL 1.0.2t code. The version allows to be used in a FIPS enabled environment. The old OpenSSL and mbed TLS implementation could have shared some more code but as we will eventually drop support for older TLS libraries, the separation makes it easier it remove that code invdidually. In FIPS mode MD5 is normally forbidden, the TLS1 PRF1 function we use, makes uses of MD5, which in the past has caused OpenVPN to segfault. The new implementation for OpenSSL version of our custom implementation has added the special flags that tell OpenSSL that this specific use of MD5 is allowed in FIPS mode. No FIPS conformitiy testing etc has been done, this is only about allowing OpenVPN on a system where FIPS mode has been enabled system wide (e.g. on RHEL derivates). Signed-off-by: Arne Schwabe <arne@rfc2549.org> --- Changes.rst | 10 +- src/openvpn/crypto_backend.h | 14 +++ src/openvpn/crypto_mbedtls.c | 134 ++++++++++++++++++++ src/openvpn/crypto_openssl.c | 165 +++++++++++++++++++++++++ src/openvpn/ssl.c | 130 +------------------ tests/unit_tests/openvpn/test_crypto.c | 32 +++++ 6 files changed, 351 insertions(+), 134 deletions(-)