1 files changed, 74 insertions, 0 deletions
diff --git a/security/openvpn20/files/patch-CVE-2013-2061 b/security/openvpn20/files/patch-CVE-2013-2061
new file mode 100644
index 000000000000..fc622b37a131
--- /dev/null
+++ b/security/openvpn20/files/patch-CVE-2013-2061
@@ -0,0 +1,74 @@
+commit 11d21349a4e7e38a025849479b36ace7c2eec2ee
+Author: Steffan Karger <steffan.karger@fox-it.com>
+Date:   Tue Mar 19 13:01:50 2013 +0100
+
+    Use constant time memcmp when comparing HMACs in openvpn_decrypt.
+    
+    Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
+    Acked-by: Gert Doering <gert@greenie.muc.de>
+    Signed-off-by: Gert Doering <gert@greenie.muc.de>
+
+diff --git a/src/openvpn/buffer.h b/src/openvpn/buffer.h
+index 7cae733..93efb09 100644
+--- ./buffer.h~
++++ ./buffer.h
+@@ -668,6 +668,10 @@ buf_read_u32 (struct buffer *buf, bool *good)
+     }
+ }
+ 
++/**
++ * 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 @@ buf_string_match (const struct buffer *src, const void *match, int size)
+   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
+--- ./crypto.c~
++++ ./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 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
+ 	  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));