[tor-commits] [tor/master] Use EVP for AES only when hardware accel is present
nickm at torproject.org
nickm at torproject.org
Fri Nov 25 15:41:44 UTC 2011
commit 8143074b3f110a41cc83335b70eb19dfe2b749b0
Author: Nick Mathewson <nickm at 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;
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