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71fa5b0a4

Denys Vlasenko

2018-12-10

SUCCESS Duration: 152s

Subject

tls: introduce FEATURE_TLS_SHA1 to make SHA1 code optional

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

networking/Config.src +11 -0 networking/tls.c +30 -6

networking/Config.src+11 -0

@@ -46,6 +46,17 @@ config VERBOSE_RESOLUTION_ERRORS
	"can't resolve 'hostname.com'" and want to know more.
	This may increase size of your executable a bit.

+	config FEATURE_TLS_SHA1
+	bool "In TLS code, support ciphers which use deprecated SHA1"
+	depends on TLS
+	default n
+	help
+	Selecting this option increases interoperability with very old
+	servers, but slightly increases code size.
+
+	Most TLS servers support SHA256 today (2018), since SHA1 is
+	considered possibly insecure (although not yet definitely broken).
+
	INSERT

	source networking/udhcp/Config.in

networking/tls.c+30 -6

@@ -6,6 +6,8 @@
	//config:config TLS
	//config: bool #No description makes it a hidden option
	//config: default n
+	//Note:
+	//Config.src also defines FEATURE_TLS_SHA1 option

	//kbuild:lib-$(CONFIG_TLS) += tls.o
	//kbuild:lib-$(CONFIG_TLS) += tls_pstm.o
@@ -394,7 +396,7 @@ static void hash_handshake(tls_state_t tls, const char fmt, const void *buffer
	dump_hex(fmt, buffer, len);
	dbg(" (%u bytes) ", (int)len);
	len = sha_peek(&tls->hsd->handshake_hash_ctx, h);
-	if (len == SHA1_OUTSIZE)
+	if (ENABLE_FEATURE_TLS_SHA1 && len == SHA1_OUTSIZE)
	dump_hex("sha1:%s\n", h, len);
	else
	if (len == SHA256_OUTSIZE)
@@ -421,6 +423,11 @@ typedef struct hmac_precomputed {
	} hmac_precomputed_t;

	typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
+	#if !ENABLE_FEATURE_TLS_SHA1
+	#define hmac_begin(pre,key,key_size,begin) \
+	hmac_begin(pre,key,key_size)
+	#define begin sha256_begin
+	#endif
	static void hmac_begin(hmac_precomputed_t pre, uint8_t key, unsigned key_size, md5sha_begin_func *begin)
	{
	uint8_t key_xor_ipad[SHA_INSIZE];
@@ -461,6 +468,7 @@ static void hmac_begin(hmac_precomputed_t pre, uint8_t key, unsigned key_size,
	md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
	md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
	}
+	#undef begin

	static unsigned hmac_sha_precomputed_v(
	hmac_precomputed_t *pre,
@@ -498,6 +506,10 @@ static unsigned hmac_sha_precomputed(hmac_precomputed_t pre_init, uint8_t out,
	return len;
	}

+	#if !ENABLE_FEATURE_TLS_SHA1
+	#define hmac(tls,out,key,key_size,...) \
+	hmac(out,key,key_size, __VA_ARGS__)
+	#endif
	static unsigned hmac(tls_state_t tls, uint8_t out, uint8_t *key, unsigned key_size, ...)
	{
	hmac_precomputed_t pre;
@@ -507,7 +519,7 @@ static unsigned hmac(tls_state_t tls, uint8_t out, uint8_t *key, unsigned key_
	va_start(va, key_size);

	hmac_begin(&pre, key, key_size,
-	(tls->MAC_size == SHA256_OUTSIZE)
+	(ENABLE_FEATURE_TLS_SHA1 \|\| tls->MAC_size == SHA256_OUTSIZE)
	? sha256_begin
	: sha1_begin
	);
@@ -1466,15 +1478,17 @@ static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, un

	static void send_client_hello_and_alloc_hsd(tls_state_t tls, const char sni)
	{
-	#define NUM_CIPHERS (13 + ALLOW_RSA_NULL_SHA256)
+	#define NUM_CIPHERS (7 + 6 * ENABLE_FEATURE_TLS_SHA1 + ALLOW_RSA_NULL_SHA256)
	static const uint8_t ciphers[] = {
	0x00,(1 + NUM_CIPHERS) * 2, //len16_be
	0x00,0xFF, //not a cipher - TLS_EMPTY_RENEGOTIATION_INFO_SCSV
	/* ^^^^^^ RFC 5746 Renegotiation Indication Extension - some servers will refuse to work with us otherwise */
+	#if ENABLE_FEATURE_TLS_SHA1
	0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
	0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
	0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
	0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
+	#endif
	0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
	// 0xC0,0x24, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
	0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
@@ -1485,12 +1499,16 @@ static void send_client_hello_and_alloc_hsd(tls_state_t tls, const char sni)
	0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
	// 0xC0,0x30, // TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
	//possibly these too:
+	#if ENABLE_FEATURE_TLS_SHA1
	// 0xC0,0x35, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
	// 0xC0,0x36, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
+	#endif
	// 0xC0,0x37, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
	// 0xC0,0x38, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
+	#if ENABLE_FEATURE_TLS_SHA1
	0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
	0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
+	#endif
	0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
	0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
	0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
@@ -1669,10 +1687,12 @@ static void get_server_hello(tls_state_t *tls)

	/* Set up encryption params based on selected cipher */
	#if 0
+	#if ENABLE_FEATURE_TLS_SHA1
	0xC0,0x09, // 1 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA - ok: wget https://is.gd/
	0xC0,0x0A, // 2 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA - ok: wget https://is.gd/
	0xC0,0x13, // 3 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA
	0xC0,0x14, // 4 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher ECDHE-RSA-AES256-SHA (might fail with older openssl)
+	#endif
	0xC0,0x23, // 5 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 - ok: wget https://is.gd/
	// 0xC0,0x24, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
	0xC0,0x27, // 6 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-SHA256
@@ -1682,12 +1702,16 @@ static void get_server_hello(tls_state_t *tls)
	0xC0,0x2F, // 8 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher ECDHE-RSA-AES128-GCM-SHA256
	// 0xC0,0x30, // TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 - openssl s_server ... -cipher ECDHE-RSA-AES256-GCM-SHA384: "decryption failed or bad record mac"
	//possibly these too:
+	#if ENABLE_FEATURE_TLS_SHA1
	// 0xC0,0x35, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA
	// 0xC0,0x36, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA
+	#endif
	// 0xC0,0x37, // TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256
	// 0xC0,0x38, // TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384 - can't do SHA384 yet
+	#if ENABLE_FEATURE_TLS_SHA1
	0x00,0x2F, // 9 TLS_RSA_WITH_AES_128_CBC_SHA - ok: openssl s_server ... -cipher AES128-SHA
	0x00,0x35, //10 TLS_RSA_WITH_AES_256_CBC_SHA - ok: openssl s_server ... -cipher AES256-SHA
+	#endif
	0x00,0x3C, //11 TLS_RSA_WITH_AES_128_CBC_SHA256 - ok: openssl s_server ... -cipher AES128-SHA256
	0x00,0x3D, //12 TLS_RSA_WITH_AES_256_CBC_SHA256 - ok: openssl s_server ... -cipher AES256-SHA256
	0x00,0x9C, //13 TLS_RSA_WITH_AES_128_GCM_SHA256 - ok: openssl s_server ... -cipher AES128-GCM-SHA256
@@ -1706,7 +1730,7 @@ static void get_server_hello(tls_state_t *tls)
	/* Odd numbered C0xx use AES128 (even ones use AES256) */
	tls->key_size = AES128_KEYSIZE;
	}
-	if (cipherid1 <= 0x14) {
+	if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x14) {
	tls->MAC_size = SHA1_OUTSIZE;
	} else
	if (cipherid1 >= 0x2B && cipherid1 <= 0x30) {
@@ -1717,13 +1741,13 @@ static void get_server_hello(tls_state_t *tls)
	}
	} else {
	/* All 00xx are RSA */
-	if (cipherid1 == 0x2F
+	if ((ENABLE_FEATURE_TLS_SHA1 && cipherid1 == 0x2F)
	\|\| cipherid1 == 0x3C
	\|\| cipherid1 == 0x9C
	) {
	tls->key_size = AES128_KEYSIZE;
	}
-	if (cipherid1 <= 0x35) {
+	if (ENABLE_FEATURE_TLS_SHA1 && cipherid1 <= 0x35) {
	tls->MAC_size = SHA1_OUTSIZE;
	} else
	if (cipherid1 == 0x9C /\|\| cipherid1 == 0x9D/) {