commit 8143074b3f110a41cc83335b70eb19dfe2b749b0 Author: Nick Mathewson nickm@torproject.org Date: Sun Nov 20 21:20:31 2011 -0500
Use EVP for AES only when hardware accel is present
Fixes bug 4525, fix on 0.2.3.8-alpha. --- changes/aes_hackery | 3 + src/common/aes.c | 120 ++++++++++++++++++++++++++++++++------------------- src/common/aes.h | 2 + src/common/crypto.c | 3 + 4 files changed, 83 insertions(+), 45 deletions(-)
diff --git a/changes/aes_hackery b/changes/aes_hackery index 739c8a0..82aae23 100644 --- a/changes/aes_hackery +++ b/changes/aes_hackery @@ -8,4 +8,7 @@ - Use OpenSSL's EVP interface for AES encryption, so that all AES operations can use hardware acceleration (if present). Resolves issue #4442. + - But only use the EVP interface when AES acceleration is enabled, + to avoid a performance regression. Resolves issue #4525. +
diff --git a/src/common/aes.c b/src/common/aes.c index 9c03b80..53c80a3 100644 --- a/src/common/aes.c +++ b/src/common/aes.c @@ -14,34 +14,28 @@ #include <assert.h> #include <stdlib.h> #include <string.h> +#include <openssl/aes.h> +#include <openssl/evp.h> +#include <openssl/engine.h> #include "compat.h" #include "aes.h" #include "util.h" #include "torlog.h"
-/* We have 2 strategies for getting AES: Via OpenSSL's AES_encrypt function, - * via OpenSSL's EVP_EncryptUpdate function. */ - -/** Defined iff we're using OpenSSL's AES functions for AES. */ -#undef USE_OPENSSL_AES -/** Defined iff we're using OpenSSL's EVP code for AES. */ -#undef USE_OPENSSL_EVP - -/* Here we pick which to use, if none is force-defined above */ -#if (!defined(USE_OPENSSL_AES) && \ - !defined(USE_OPENSSL_EVP)) - -#define USE_OPENSSL_EVP - +#ifdef ANDROID +/* Android's OpenSSL seems to have removed all of its Engine support. */ +#define DISABLE_ENGINES #endif
+/* We have 2 strategies for getting AES: Via OpenSSL's AES_encrypt function, + * via OpenSSL's EVP_EncryptUpdate function. + * + * If there's any hardware acceleration in play, we want to be using EVP_* so + * we can get it. Otherwise, we'll want AES_*, which seems to be about 5% + * faster than indirecting through the EVP layer. + */ + /* Include OpenSSL headers as needed. */ -#ifdef USE_OPENSSL_AES -# include <openssl/aes.h> -#endif -#ifdef USE_OPENSSL_EVP -# include <openssl/evp.h> -#endif
/*======================================================================*/ /* Interface to AES code, and counter implementation */ @@ -49,11 +43,10 @@ /** Implements an AES counter-mode cipher. */ struct aes_cnt_cipher { /** This next element (however it's defined) is the AES key. */ -#if defined(USE_OPENSSL_EVP) - EVP_CIPHER_CTX key; -#elif defined(USE_OPENSSL_AES) - AES_KEY key; -#endif + union { + EVP_CIPHER_CTX evp; + AES_KEY aes; + } key;
#if !defined(WORDS_BIGENDIAN) #define USING_COUNTER_VARS @@ -78,8 +71,45 @@ struct aes_cnt_cipher { uint8_t buf[16]; /** Our current stream position within buf. */ uint8_t pos; + + /** True iff we're using the evp implementation of this cipher. */ + uint8_t using_evp; };
+/** True if we should prefer the EVP implementation for AES, either because + * we're testing it or because we have hardware acceleration configured */ +static int should_use_EVP = 0; + +/** Check whether we should use the EVP interface for AES. If <b>force_val</b> + * is nonnegative, we use use EVP iff it is true. Otherwise, we use EVP + * if there is an engine enabled for aes-ecb. */ +int +evaluate_evp_for_aes(int force_val) +{ + ENGINE *e; + + if (force_val >= 0) { + should_use_EVP = force_val; + return 0; + } +#ifdef DISABLE_ENGINES + should_use_EVP = 0; +#else + e = ENGINE_get_cipher_engine(NID_aes_128_ecb); + + if (e) { + log_notice(LD_CRYPTO, "AES engine "%s" found; using EVP_* functions.", + ENGINE_get_name(e)); + should_use_EVP = 1; + } else { + log_notice(LD_CRYPTO, "No AES engine found; using AES_* functions."); + should_use_EVP = 0; + } +#endif + + return 0; +} + #if !defined(USING_COUNTER_VARS) #define COUNTER(c, n) ((c)->ctr_buf.buf32[3-(n)]) #else @@ -100,15 +130,13 @@ _aes_fill_buf(aes_cnt_cipher_t *cipher) * None of these issues are insurmountable in principle. */
-#if defined(USE_OPENSSL_EVP) - { + if (cipher->using_evp) { int outl=16, inl=16; - EVP_EncryptUpdate(&cipher->key, cipher->buf, &outl, + EVP_EncryptUpdate(&cipher->key.evp, cipher->buf, &outl, cipher->ctr_buf.buf, inl); + } else { + AES_encrypt(cipher->ctr_buf.buf, cipher->buf, &cipher->key.aes); } -#elif defined(USE_OPENSSL_AES) - AES_encrypt(cipher->ctr_buf.buf, cipher->buf, &cipher->key); -#endif }
/** @@ -129,18 +157,20 @@ aes_new_cipher(void) void aes_set_key(aes_cnt_cipher_t *cipher, const char *key, int key_bits) { -#if defined(USE_OPENSSL_EVP) - const EVP_CIPHER *c; - switch (key_bits) { - case 128: c = EVP_aes_128_ecb(); break; - case 192: c = EVP_aes_192_ecb(); break; - case 256: c = EVP_aes_256_ecb(); break; - default: tor_assert(0); + if (should_use_EVP) { + const EVP_CIPHER *c; + switch (key_bits) { + case 128: c = EVP_aes_128_ecb(); break; + case 192: c = EVP_aes_192_ecb(); break; + case 256: c = EVP_aes_256_ecb(); break; + default: tor_assert(0); + } + EVP_EncryptInit(&cipher->key.evp, c, (const unsigned char*)key, NULL); + cipher->using_evp = 1; + } else { + AES_set_encrypt_key((const unsigned char *)key, key_bits, &cipher->key.aes); + cipher->using_evp = 0; } - EVP_EncryptInit(&cipher->key, c, (const unsigned char*)key, NULL); -#elif defined(USE_OPENSSL_AES) - AES_set_encrypt_key((const unsigned char *)key, key_bits, &(cipher->key)); -#endif #ifdef USING_COUNTER_VARS cipher->counter0 = 0; cipher->counter1 = 0; @@ -161,9 +191,9 @@ aes_free_cipher(aes_cnt_cipher_t *cipher) { if (!cipher) return; -#ifdef USE_OPENSSL_EVP - EVP_CIPHER_CTX_cleanup(&cipher->key); -#endif + if (cipher->using_evp) { + EVP_CIPHER_CTX_cleanup(&cipher->key.evp); + } memset(cipher, 0, sizeof(aes_cnt_cipher_t)); tor_free(cipher); } diff --git a/src/common/aes.h b/src/common/aes.h index b259194..221e846 100644 --- a/src/common/aes.h +++ b/src/common/aes.h @@ -24,5 +24,7 @@ void aes_crypt(aes_cnt_cipher_t *cipher, const char *input, size_t len, void aes_crypt_inplace(aes_cnt_cipher_t *cipher, char *data, size_t len); void aes_set_iv(aes_cnt_cipher_t *cipher, const char *iv);
+int evaluate_evp_for_aes(int force_value); + #endif
diff --git a/src/common/crypto.c b/src/common/crypto.c index f2ef833..55ad5fd 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -276,6 +276,9 @@ crypto_global_init(int useAccel, const char *accelName, const char *accelDir) } else { log_info(LD_CRYPTO, "NOT using OpenSSL engine support."); } + + evaluate_evp_for_aes(-1); + return crypto_seed_rng(1); } return 0;