[Midnightbsd-cvs] src [7194] trunk/crypto/openssh: Fix two OpenSSH security issues:

[laffer1 at midnightbsd.org]

Revision: 7194
          http://svnweb.midnightbsd.org/src/?rev=7194
Author:   laffer1
Date:     2015-07-28 20:35:21 -0400 (Tue, 28 Jul 2015)
Log Message:
-----------
Fix two OpenSSH security issues:

CVE-2014-2653 and CVE-2015-5600

Attackers can bypass MaxAuthTries and brute force passwords. Clients will
not properly validate DNS SSHFP records that offer a certificate. (rarely used)

Modified Paths:
--------------
    trunk/crypto/openssh/auth2-chall.c
    trunk/crypto/openssh/sshconnect.c

Modified: trunk/crypto/openssh/auth2-chall.c
===================================================================
--- trunk/crypto/openssh/auth2-chall.c	2015-07-29 00:31:36 UTC (rev 7193)
+++ trunk/crypto/openssh/auth2-chall.c	2015-07-29 00:35:21 UTC (rev 7194)
@@ -82,6 +82,7 @@
 	void *ctxt;
 	KbdintDevice *device;
 	u_int nreq;
+	u_int devices_done;
 };
 
 #ifdef USE_PAM
@@ -168,11 +169,15 @@
 		if (len == 0)
 			break;
 		for (i = 0; devices[i]; i++) {
-			if (!auth2_method_allowed(authctxt,
+			if ((kbdintctxt->devices_done & (1 << i)) != 0 ||
+			    !auth2_method_allowed(authctxt,
 			    "keyboard-interactive", devices[i]->name))
 				continue;
-			if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
+			if (strncmp(kbdintctxt->devices, devices[i]->name,
+			    len) == 0) {
 				kbdintctxt->device = devices[i];
+				kbdintctxt->devices_done |= 1 << i;
+			}
 		}
 		t = kbdintctxt->devices;
 		kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;

Modified: trunk/crypto/openssh/sshconnect.c
===================================================================
--- trunk/crypto/openssh/sshconnect.c	2015-07-29 00:31:36 UTC (rev 7193)
+++ trunk/crypto/openssh/sshconnect.c	2015-07-29 00:35:21 UTC (rev 7194)
@@ -1219,29 +1219,39 @@
 {
 	int flags = 0;
 	char *fp;
+	Key *plain = NULL;
 
 	fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
 	debug("Server host key: %s %s", key_type(host_key), 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,