- dtucker@cvs.openbsd.org 2014/01/25 10:12:50
[cipher.c cipher.h kex.c kex.h kexgexc.c]
Add a special case for the DH group size for 3des-cbc, which has an
effective strength much lower than the key size. This causes problems
with some cryptlib implementations, which don't support group sizes larger
than 4k but also don't use the largest group size it does support as
specified in the RFC. Based on a patch from Petr Lautrbach at Redhat,
reduced by me with input from Markus. ok djm@ markus@
diff --git a/ChangeLog b/ChangeLog
index 44e56f4..64da7a4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+20130126
+ - OpenBSD CVS Sync
+ - dtucker@cvs.openbsd.org 2014/01/25 10:12:50
+ [cipher.c cipher.h kex.c kex.h kexgexc.c]
+ Add a special case for the DH group size for 3des-cbc, which has an
+ effective strength much lower than the key size. This causes problems
+ with some cryptlib implementations, which don't support group sizes larger
+ than 4k but also don't use the largest group size it does support as
+ specified in the RFC. Based on a patch from Petr Lautrbach at Redhat,
+ reduced by me with input from Markus. ok djm@ markus@
+
20130125
- (djm) [configure.ac] Fix detection of capsicum sandbox on FreeBSD
- (djm) [configure.ac] Do not attempt to use capsicum sandbox unless
diff --git a/cipher.c b/cipher.c
index 76e6c59..2476e65 100644
--- a/cipher.c
+++ b/cipher.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.93 2013/12/06 13:34:54 markus Exp $ */
+/* $OpenBSD: cipher.c,v 1.94 2014/01/25 10:12:50 dtucker Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -142,6 +142,14 @@
}
u_int
+cipher_seclen(const Cipher *c)
+{
+ if (strcmp("3des-cbc", c->name) == 0)
+ return 14;
+ return cipher_keylen(c);
+}
+
+u_int
cipher_authlen(const Cipher *c)
{
return (c->auth_len);
diff --git a/cipher.h b/cipher.h
index d782456..133d2e7 100644
--- a/cipher.h
+++ b/cipher.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.h,v 1.43 2013/12/06 13:34:54 markus Exp $ */
+/* $OpenBSD: cipher.h,v 1.44 2014/01/25 10:12:50 dtucker Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -89,6 +89,7 @@
void cipher_set_key_string(CipherContext *, const Cipher *, const char *, int);
u_int cipher_blocksize(const Cipher *);
u_int cipher_keylen(const Cipher *);
+u_int cipher_seclen(const Cipher *);
u_int cipher_authlen(const Cipher *);
u_int cipher_ivlen(const Cipher *);
u_int cipher_is_cbc(const Cipher *);
diff --git a/kex.c b/kex.c
index 7d054cd..39d16f8 100644
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.95 2014/01/12 08:13:13 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.96 2014/01/25 10:12:50 dtucker Exp $ */
/*
* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
*
@@ -458,7 +458,7 @@
char **my, **peer;
char **cprop, **sprop;
int nenc, nmac, ncomp;
- u_int mode, ctos, need, authlen;
+ u_int mode, ctos, need, dh_need, authlen;
int first_kex_follows, type;
my = kex_buf2prop(&kex->my, NULL);
@@ -506,7 +506,7 @@
choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
- need = 0;
+ need = dh_need = 0;
for (mode = 0; mode < MODE_MAX; mode++) {
newkeys = kex->newkeys[mode];
if (need < newkeys->enc.key_len)
@@ -517,9 +517,12 @@
need = newkeys->enc.iv_len;
if (need < newkeys->mac.key_len)
need = newkeys->mac.key_len;
+ if (dh_need < cipher_seclen(newkeys->enc.cipher))
+ dh_need = cipher_seclen(newkeys->enc.cipher);
}
/* XXX need runden? */
kex->we_need = need;
+ kex->dh_need = dh_need;
/* ignore the next message if the proposals do not match */
if (first_kex_follows && !proposals_match(my, peer) &&
diff --git a/kex.h b/kex.h
index 7e2878f..1aa3ec2 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.h,v 1.60 2014/01/12 08:13:13 djm Exp $ */
+/* $OpenBSD: kex.h,v 1.61 2014/01/25 10:12:50 dtucker Exp $ */
/*
* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
@@ -124,6 +124,7 @@
u_int session_id_len;
Newkeys *newkeys[MODE_MAX];
u_int we_need;
+ u_int dh_need;
int server;
char *name;
int hostkey_type;
diff --git a/kexgexc.c b/kexgexc.c
index a69ff27..629b5fb 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.15 2014/01/12 08:13:13 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.16 2014/01/25 10:12:50 dtucker Exp $ */
/*
* Copyright (c) 2000 Niels Provos. All rights reserved.
* Copyright (c) 2001 Markus Friedl. All rights reserved.
@@ -58,7 +58,7 @@
int min, max, nbits;
DH *dh;
- nbits = dh_estimate(kex->we_need * 8);
+ nbits = dh_estimate(kex->dh_need * 8);
if (datafellows & SSH_OLD_DHGEX) {
/* Old GEX request */