- markus@cvs.openbsd.org 2009/01/26 09:58:15

     [cipher.c cipher.h packet.c]
     Work around the CPNI-957037 Plaintext Recovery Attack by always
     reading 256K of data on packet size or HMAC errors (in CBC mode only).
     Help, feedback and ok djm@
     Feedback from Martin Albrecht and Paterson Kenny

1 files changed, 28 insertions, 21 deletions

diff --git a/cipher.c b/cipher.c
index b264063c4..bb5c0ac3a 100644
--- a/cipher.c
+++ b/cipher.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt Exp $ */
+/* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -63,31 +63,32 @@ struct Cipher {
         u_int   block_size;
         u_int   key_len;
         u_int   discard_len;
+        u_int   cbc_mode;
         const EVP_CIPHER        *(*evptype)(void);
 } ciphers[] = {
-        { "none",               SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null },
-        { "des",                SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc },
-        { "3des",               SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des },
-        { "blowfish",           SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf },
-
-        { "3des-cbc",           SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc },
-        { "blowfish-cbc",       SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc },
-        { "cast128-cbc",        SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc },
-        { "arcfour",            SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 },
-        { "arcfour128",         SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 },
-        { "arcfour256",         SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 },
-        { "aes128-cbc",         SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc },
-        { "aes192-cbc",         SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc },
-        { "aes256-cbc",         SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
+        { "none",               SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
+        { "des",                SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
+        { "3des",               SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
+        { "blowfish",           SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
+
+        { "3des-cbc",           SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
+        { "blowfish-cbc",       SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
+        { "cast128-cbc",        SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
+        { "arcfour",            SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
+        { "arcfour128",         SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
+        { "arcfour256",         SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
+        { "aes128-cbc",         SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
+        { "aes192-cbc",         SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
+        { "aes256-cbc",         SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
         { "rijndael-cbc@lysator.liu.se",
-                                SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc },
-        { "aes128-ctr",         SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr },
-        { "aes192-ctr",         SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr },
-        { "aes256-ctr",         SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr },
+                                SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
+        { "aes128-ctr",         SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr },
+        { "aes192-ctr",         SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr },
+        { "aes256-ctr",         SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr },
 #ifdef USE_CIPHER_ACSS
-        { "acss@openssh.org",   SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss },
+        { "acss@openssh.org",   SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
 #endif
-        { NULL,                 SSH_CIPHER_INVALID, 0, 0, 0, NULL }
+        { NULL,                 SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
 };
 
 /*--*/
@@ -111,6 +112,12 @@ cipher_get_number(const Cipher *c)
 }
 
 u_int
+cipher_is_cbc(const Cipher *c)
+{
+        return (c->cbc_mode);
+}
+
+u_int
 cipher_mask_ssh1(int client)
 {
         u_int mask = 0;