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authorChen Qi <Qi.Chen@windriver.com>2014-05-13 15:46:27 +0800
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-05-13 19:26:34 +0100
commit7b2fff61b3d1c0566429793ee348fa8978ef0cba (patch)
tree248c4e2993e9d36a51c4b6b476011d7eec034659 /meta
parenta8d3b8979c27a8dc87971b66a1d9d9282f660596 (diff)
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openssh: fix for CVE-2014-2653
The verify_host_key function in sshconnect.c in the client in OpenSSH 6.6 and earlier allows remote servers to trigger the skipping of SSHFP DNS RR checking by presenting an unacceptable HostCertificate. Signed-off-by: Chen Qi <Qi.Chen@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'meta')
-rw-r--r--meta/recipes-connectivity/openssh/openssh/openssh-CVE-2014-2653.patch114
-rw-r--r--meta/recipes-connectivity/openssh/openssh_6.5p1.bb3
2 files changed, 116 insertions, 1 deletions
diff --git a/meta/recipes-connectivity/openssh/openssh/openssh-CVE-2014-2653.patch b/meta/recipes-connectivity/openssh/openssh/openssh-CVE-2014-2653.patch
new file mode 100644
index 0000000000..674d186044
--- /dev/null
+++ b/meta/recipes-connectivity/openssh/openssh/openssh-CVE-2014-2653.patch
@@ -0,0 +1,114 @@
+Upstream-Status: Backport
+
+This CVE could be removed if openssh is upgrade to 6.6 or higher.
+Below are some details.
+
+Attempt SSHFP lookup even if server presents a certificate
+
+Reference:
+https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=742513
+
+If an ssh server presents a certificate to the client, then the client
+does not check the DNS for SSHFP records. This means that a malicious
+server can essentially disable DNS-host-key-checking, which means the
+client will fall back to asking the user (who will just say "yes" to
+the fingerprint, sadly).
+
+This patch means that the ssh client will, if necessary, extract the
+server key from the proffered certificate, and attempt to verify it
+against the DNS. The patch was written by Mark Wooding
+<mdw@distorted.org.uk>. I modified it to add one debug2 call, reviewed
+it, and tested it.
+
+Signed-off-by: Matthew Vernon <matthew@debian.org>
+Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
+---
+--- a/sshconnect.c
++++ b/sshconnect.c
+@@ -1210,36 +1210,63 @@ fail:
+ return -1;
+ }
+
++static int
++check_host_key_sshfp(char *host, struct sockaddr *hostaddr, Key *host_key)
++{
++ int rc = -1;
++ int flags = 0;
++ Key *raw_key = NULL;
++
++ if (!options.verify_host_key_dns)
++ goto done;
++
++ /* XXX certs are not yet supported for DNS; try looking the raw key
++ * up in the DNS anyway.
++ */
++ if (key_is_cert(host_key)) {
++ debug2("Extracting key from cert for SSHFP lookup");
++ raw_key = key_from_private(host_key);
++ if (key_drop_cert(raw_key))
++ fatal("Couldn't drop certificate");
++ host_key = raw_key;
++ }
++
++ if (verify_host_key_dns(host, hostaddr, host_key, &flags))
++ goto done;
++
++ if (flags & DNS_VERIFY_FOUND) {
++
++ if (options.verify_host_key_dns == 1 &&
++ flags & DNS_VERIFY_MATCH &&
++ flags & DNS_VERIFY_SECURE) {
++ rc = 0;
++ } else 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.");
++ }
++ }
++
++done:
++ if (raw_key)
++ key_free(raw_key);
++ return rc;
++}
++
+ /* returns 0 if key verifies or -1 if key does NOT verify */
+ int
+ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
+ {
+- int flags = 0;
+ char *fp;
+
+ 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 (check_host_key_sshfp(host, hostaddr, host_key) == 0)
++ return 0;
+
+ return check_host_key(host, hostaddr, options.port, host_key, RDRW,
+ options.user_hostfiles, options.num_user_hostfiles,
+--
+1.7.9.5
+
diff --git a/meta/recipes-connectivity/openssh/openssh_6.5p1.bb b/meta/recipes-connectivity/openssh/openssh_6.5p1.bb
index 230f38ab31..795e085202 100644
--- a/meta/recipes-connectivity/openssh/openssh_6.5p1.bb
+++ b/meta/recipes-connectivity/openssh/openssh_6.5p1.bb
@@ -30,7 +30,8 @@ SRC_URI = "ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-${PV}.tar.
file://volatiles.99_sshd \
file://add-test-support-for-busybox.patch \
file://run-ptest \
- file://openssh-CVE-2014-2532.patch"
+ file://openssh-CVE-2014-2532.patch \
+ file://openssh-CVE-2014-2653.patch"
PAM_SRC_URI = "file://sshd"