openssl: optimizations based on ARCH/small flash

Add a patch to enable the option to change the default ciphersuite list
ordering to prefer ChaCha20 over AES-GCM.  This is used by default for
all platforms, except for x86_64 and aarch64. The assumption is that
only the latter have AES-specific CPU instructions and asm code that
uses them in openssl.  Chacha20Poly1305 is 3x faster than AES-256 in
systems without AES instructions, with an equivalent strength.

Disable error messages by default except for devices with small flash or
RAM, to aid debugging.

Disable ASM by default on arm platform with small flash.  Size
difference on mips and powerpc, the other platforms with small flash
devices, are not really relevant (using 100K as a threshold).  All of
the affected platforms are source-only anyway.

Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>
This commit is contained in:
Eneas U de Queiroz 2018-10-24 16:28:59 -03:00 committed by Hauke Mehrtens
parent d872d00b2f
commit 2eeb2853ed
3 changed files with 98 additions and 1 deletions

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@ -4,6 +4,7 @@ comment "Build Options"
config OPENSSL_OPTIMIZE_SPEED
bool
default y if x86_64 || i386
prompt "Enable optimization for speed instead of size"
select OPENSSL_WITH_ASM
help
@ -15,7 +16,7 @@ config OPENSSL_OPTIMIZE_SPEED
config OPENSSL_WITH_ASM
bool
default y
default y if !SMALL_FLASH || !arm
prompt "Compile with optimized assembly code"
depends on !arc
help
@ -63,6 +64,7 @@ config OPENSSL_NO_DEPRECATED
config OPENSSL_WITH_ERROR_MESSAGES
bool
default y if !SMALL_FLASH && !LOW_MEMORY_FOOTPRINT
prompt "Include error messages"
help
This option aids debugging, but increases package size and
@ -147,6 +149,18 @@ config OPENSSL_WITH_CHACHA_POLY1305
It is 3x faster than AES, when not using a CPU with AES-specific
instructions, as is the case of most embedded devices.
config OPENSSL_PREFER_CHACHA_OVER_GCM
bool
default y if !x86_64 && !aarch64
prompt "Prefer ChaCha20-Poly1305 over AES-GCM by default"
depends on OPENSSL_WITH_CHACHA_POLY1305
help
The default openssl preference is for AES-GCM before ChaCha, but
that takes into account AES-NI capable chips. It is not the
case with most embedded chips, so it may be better to invert
that preference. This is just for the default case. The
application can always override this.
config OPENSSL_WITH_PSK
bool
default y

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@ -35,6 +35,7 @@ PKG_CONFIG_DEPENDS:= \
CONFIG_OPENSSL_ENGINE_CRYPTO \
CONFIG_OPENSSL_NO_DEPRECATED \
CONFIG_OPENSSL_OPTIMIZE_SPEED \
CONFIG_OPENSSL_PREFER_CHACHA_OVER_GCM \
CONFIG_OPENSSL_WITH_ARIA \
CONFIG_OPENSSL_WITH_ASM \
CONFIG_OPENSSL_WITH_ASYNC \
@ -153,6 +154,10 @@ endif
ifndef CONFIG_OPENSSL_WITH_CHACHA_POLY1305
OPENSSL_OPTIONS += no-chacha no-poly1305
else
ifdef CONFIG_OPENSSL_PREFER_CHACHA_OVER_GCM
OPENSSL_OPTIONS += -DOPENSSL_PREFER_CHACHA_OVER_GCM
endif
endif
ifndef CONFIG_OPENSSL_WITH_ASYNC

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@ -0,0 +1,78 @@
From 286e015bf0d30530707a5e7b3b871509f2ab50d7 Mon Sep 17 00:00:00 2001
From: Eneas U de Queiroz <cote2004-github@yahoo.com>
Date: Thu, 27 Sep 2018 08:44:39 -0300
Subject: Add OPENSSL_PREFER_CHACHA_OVER_GCM option
This enables a compile-time option to prefer ChaCha20-Poly1305 over
AES-GCM in the openssl default ciphersuite, which is useful in systems
without AES specific CPU instructions.
OPENSSL_PREFER_CHACHA_OVER_GCM must be defined to enable it.
Note that this does not have the same effect as the
SL_OP_PRIORITIZE_CHACHA option, which prioritizes ChaCha20-Poly1305 only
when the client has it on top of its ciphersuite preference.
Signed-off-by: Eneas U de Queiroz <cote2004-github@yahoo.com>
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -173,9 +173,15 @@ extern "C" {
# define SSL_DEFAULT_CIPHER_LIST "ALL:!COMPLEMENTOFDEFAULT:!eNULL"
/* This is the default set of TLSv1.3 ciphersuites */
# if !defined(OPENSSL_NO_CHACHA) && !defined(OPENSSL_NO_POLY1305)
-# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
- "TLS_CHACHA20_POLY1305_SHA256:" \
- "TLS_AES_128_GCM_SHA256"
+# ifdef OPENSSL_PREFER_CHACHA_OVER_GCM
+# define TLS_DEFAULT_CIPHERSUITES "TLS_CHACHA20_POLY1305_SHA256:" \
+ "TLS_AES_256_GCM_SHA384:" \
+ "TLS_AES_128_GCM_SHA256"
+# else
+# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
+ "TLS_CHACHA20_POLY1305_SHA256:" \
+ "TLS_AES_128_GCM_SHA256"
+# endif
# else
# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
"TLS_AES_128_GCM_SHA256"
--- a/ssl/ssl_ciph.c
+++ b/ssl/ssl_ciph.c
@@ -1464,11 +1464,29 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_
ssl_cipher_apply_rule(0, SSL_kECDHE, 0, 0, 0, 0, 0, CIPHER_DEL, -1, &head,
&tail);
+ /*
+ * If OPENSSL_PREFER_CHACHA_OVER_GCM is defined, ChaCha20_Poly1305
+ * will be placed before AES-256. Otherwise, the default behavior of
+ * preferring GCM over CHACHA is used.
+ * This is useful for systems that do not have AES-specific CPU
+ * instructions, where ChaCha20-Poly1305 is 3 times faster than AES.
+ * Note that this does not have the same effect as the SSL_OP_PRIORITIZE_CHACHA
+ * option, which prioritizes ChaCha20-Poly1305 only when the client has it on top
+ * of its ciphersuite preference.
+ */
+
+#ifdef OPENSSL_PREFER_CHACHA_OVER_GCM
+ ssl_cipher_apply_rule(0, 0, 0, SSL_CHACHA20, 0, 0, 0, CIPHER_ADD, -1,
+ &head, &tail);
+ ssl_cipher_apply_rule(0, 0, 0, SSL_AESGCM, 0, 0, 0, CIPHER_ADD, -1,
+ &head, &tail);
+#else
/* Within each strength group, we prefer GCM over CHACHA... */
ssl_cipher_apply_rule(0, 0, 0, SSL_AESGCM, 0, 0, 0, CIPHER_ADD, -1,
&head, &tail);
ssl_cipher_apply_rule(0, 0, 0, SSL_CHACHA20, 0, 0, 0, CIPHER_ADD, -1,
&head, &tail);
+#endif
/*
* ...and generally, our preferred cipher is AES.
@@ -1524,7 +1542,7 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_
* Within each group, ciphers remain sorted by strength and previous
* preference, i.e.,
* 1) ECDHE > DHE
- * 2) GCM > CHACHA
+ * 2) GCM > CHACHA, reversed if OPENSSL_PREFER_CHACHA_OVER_GCM is defined
* 3) AES > rest
* 4) TLS 1.2 > legacy
*