From c28dda794f72957a6a22f852217bb8921b3e5f4e Mon Sep 17 00:00:00 2001 From: Alberto Gonzalez Iniesta Date: Fri, 17 May 2013 11:55:58 +0200 Subject: Fix CVE-2013-2061 --- debian/patches/cve-2013-2061.patch | 81 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 debian/patches/cve-2013-2061.patch (limited to 'debian/patches/cve-2013-2061.patch') diff --git a/debian/patches/cve-2013-2061.patch b/debian/patches/cve-2013-2061.patch new file mode 100644 index 0000000..531a27b --- /dev/null +++ b/debian/patches/cve-2013-2061.patch @@ -0,0 +1,81 @@ +From 11d21349a4e7e38a025849479b36ace7c2eec2ee Mon Sep 17 00:00:00 2001 +From: Steffan Karger +Date: Tue, 19 Mar 2013 13:01:50 +0100 +Subject: [PATCH] Use constant time memcmp when comparing HMACs in + openvpn_decrypt. + +Signed-off-by: Steffan Karger +Acked-by: Gert Doering +Signed-off-by: Gert Doering +--- + src/openvpn/buffer.h | 8 ++++++++ + src/openvpn/crypto.c | 20 +++++++++++++++++++- + 2 files changed, 27 insertions(+), 1 deletion(-) + +diff --git a/src/openvpn/buffer.h b/src/openvpn/buffer.h +index 7cae733..93efb09 100644 +--- a/src/openvpn/buffer.h ++++ b/src/openvpn/buffer.h +@@ -668,6 +668,10 @@ bool openvpn_snprintf(char *str, size_t size, const char *format, ...) + } + } + ++/** ++ * Compare src buffer contents with match. ++ * *NOT* constant time. Do not use when comparing HMACs. ++ */ + static inline bool + buf_string_match (const struct buffer *src, const void *match, int size) + { +@@ -676,6 +680,10 @@ bool openvpn_snprintf(char *str, size_t size, const char *format, ...) + return memcmp (BPTR (src), match, size) == 0; + } + ++/** ++ * Compare first size bytes of src buffer contents with match. ++ * *NOT* constant time. Do not use when comparing HMACs. ++ */ + static inline bool + buf_string_match_head (const struct buffer *src, const void *match, int size) + { +diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c +index 405c0aa..d9adf5b 100644 +--- a/src/openvpn/crypto.c ++++ b/src/openvpn/crypto.c +@@ -65,6 +65,24 @@ + #define CRYPT_ERROR(format) \ + do { msg (D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false) + ++/** ++ * As memcmp(), but constant-time. ++ * Returns 0 when data is equal, non-zero otherwise. ++ */ ++static int ++memcmp_constant_time (const void *a, const void *b, size_t size) { ++ const uint8_t * a1 = a; ++ const uint8_t * b1 = b; ++ int ret = 0; ++ size_t i; ++ ++ for (i = 0; i < size; i++) { ++ ret |= *a1++ ^ *b1++; ++ } ++ ++ return ret; ++} ++ + void + openvpn_encrypt (struct buffer *buf, struct buffer work, + const struct crypto_options *opt, +@@ -244,7 +262,7 @@ + hmac_ctx_final (ctx->hmac, local_hmac); + + /* Compare locally computed HMAC with packet HMAC */ +- if (memcmp (local_hmac, BPTR (buf), hmac_len)) ++ if (memcmp_constant_time (local_hmac, BPTR (buf), hmac_len)) + CRYPT_ERROR ("packet HMAC authentication failed"); + + ASSERT (buf_advance (buf, hmac_len)); +-- +1.8.1.6 + -- cgit v1.2.3