[openssh/f20: 10/12] prevent a server from skipping SSHFP lookup (#1081338) CVE-2014-2653

[plautrba]

commit d271e022960c924903f1b81fa684da3055152d88
Author: Petr Lautrbach <plautrba at redhat.com>
Date:   Wed May 14 18:04:10 2014 +0200

    prevent a server from skipping SSHFP lookup (#1081338)
    CVE-2014-2653

 openssh-6.4p1-CVE-2014-2653.patch |   80 +++++++++++++++++++++++++++++++++++++
 openssh.spec                      |    4 ++
 2 files changed, 84 insertions(+), 0 deletions(-)
---
diff --git a/openssh-6.4p1-CVE-2014-2653.patch b/openssh-6.4p1-CVE-2014-2653.patch
new file mode 100644
index 0000000..27f3fa3
--- /dev/null
+++ b/openssh-6.4p1-CVE-2014-2653.patch
@@ -0,0 +1,80 @@
+diff --git a/ChangeLog b/ChangeLog
+index 29d70ec..a0fb67e 100644
+--- a/ChangeLog
++++ b/ChangeLog
+@@ -1,3 +1,14 @@
++20140420
++   - djm at cvs.openbsd.org 2014/04/01 03:34:10
++     [sshconnect.c]
++     When using VerifyHostKeyDNS with a DNSSEC resolver, down-convert any
++     certificate keys to plain keys and attempt SSHFP resolution.
++     
++     Prevents a server from skipping SSHFP lookup and forcing a new-hostkey
++     dialog by offering only certificate keys.
++     
++     Reported by mcv21 AT cam.ac.uk
++
+ 20131010
+  - dtucker at cvs.openbsd.org 2013/10/08 11:42:13
+    [dh.c dh.h]
+diff --git a/sshconnect.c b/sshconnect.c
+index ddc167e..4d8c718 100644
+--- a/sshconnect.c
++++ b/sshconnect.c
+@@ -1136,30 +1136,40 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
+ {
+ 	int flags = 0;
+ 	char *fp;
++	Key *plain = NULL;
+ 
+ 	fp = key_selected_fingerprint(host_key, SSH_FP_HEX);
+ 	debug("Server host key: %s %s%s", key_type(host_key),
+ 	    key_fingerprint_prefix(), fp);
+ 	free(fp);
+ 
+-	/* XXX certs are not yet supported for DNS */
+-	if (!key_is_cert(host_key) && options.verify_host_key_dns &&
+-	    verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
+-		if (flags & DNS_VERIFY_FOUND) {
+-
+-			if (options.verify_host_key_dns == 1 &&
+-			    flags & DNS_VERIFY_MATCH &&
+-			    flags & DNS_VERIFY_SECURE)
+-				return 0;
+-
+-			if (flags & DNS_VERIFY_MATCH) {
+-				matching_host_key_dns = 1;
+-			} else {
+-				warn_changed_key(host_key);
+-				error("Update the SSHFP RR in DNS with the new "
+-				    "host key to get rid of this message.");
++	if (options.verify_host_key_dns) {
++		/*
++		 * XXX certs are not yet supported for DNS, so downgrade
++		 * them and try the plain key.
++		 */
++		plain = key_from_private(host_key);
++		if (key_is_cert(plain))
++			key_drop_cert(plain);
++		if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
++			if (flags & DNS_VERIFY_FOUND) {
++				if (options.verify_host_key_dns == 1 &&
++				    flags & DNS_VERIFY_MATCH &&
++				    flags & DNS_VERIFY_SECURE) {
++					key_free(plain);
++					return 0;
++				}
++				if (flags & DNS_VERIFY_MATCH) {
++					matching_host_key_dns = 1;
++				} else {
++					warn_changed_key(plain);
++					error("Update the SSHFP RR in DNS "
++					    "with the new host key to get rid "
++					    "of this message.");
++				}
+ 			}
+ 		}
++		key_free(plain);
+ 	}
+ 
+ 	return check_host_key(host, hostaddr, options.port, host_key, RDRW,
diff --git a/openssh.spec b/openssh.spec
index 3e75f2c..5b78b54 100644
--- a/openssh.spec
+++ b/openssh.spec
@@ -190,6 +190,9 @@ Patch905: openssh-6.4p1-legacy-ssh-copy-id.patch
 Patch906: openssh-6.4p1-fromto-remote.patch
 # Try CLOCK_BOOTTIME with fallback (#1091992)
 Patch907: openssh-6.4p1-CLOCK_BOOTTIME.patch
+# Prevents a server from skipping SSHFP lookup and forcing a new-hostkey
+# dialog by offering only certificate keys. (#1081338)
+Patch908: openssh-6.4p1-CVE-2014-2653.patch
 
 
 License: BSD
@@ -416,6 +419,7 @@ popd
 %patch905 -p1 -b .legacy-ssh-copy-id
 %patch906 -p1 -b .fromto-remote
 %patch907 -p1 -b .CLOCK_BOOTTIME
+%patch908 -p1 -b .CVE-2014-2653
 
 %if 0
 # Nothing here yet