GSSAPI key exchange support

This patch has been rejected upstream: "None of the OpenSSH developers are
in favour of adding this, and this situation has not changed for several
years.  This is not a slight on Simon's patch, which is of fine quality, but
just that a) we don't trust GSSAPI implementations that much and b) we don't
like adding new KEX since they are pre-auth attack surface.  This one is
particularly scary, since it requires hooks out to typically root-owned
system resources."

However, quite a lot of people rely on this in Debian, and it's better to
have it merged into the main openssh package rather than having separate
-krb5 packages (as we used to have).  It seems to have a generally good
security history.

Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1242
Last-Updated: 2018-10-20

Patch-Name: gssapi.patch

1 files changed, 14 insertions, 0 deletions

diff --git a/kex.h b/kex.h
index 593de1208..4e5ead839 100644
--- a/kex.h
+++ b/kex.h
@@ -100,6 +100,9 @@ enum kex_exchange {
         KEX_DH_GEX_SHA256,
         KEX_ECDH_SHA2,
         KEX_C25519_SHA256,
+        KEX_GSS_GRP1_SHA1,
+        KEX_GSS_GRP14_SHA1,
+        KEX_GSS_GEX_SHA1,
         KEX_MAX
 };
 
@@ -148,6 +151,12 @@ struct kex {
         u_int   flags;
         int     hash_alg;
         int     ec_nid;
+#ifdef GSSAPI
+        int     gss_deleg_creds;
+        int     gss_trust_dns;
+        char    *gss_host;
+        char    *gss_client;
+#endif
         char    *client_version_string;
         char    *server_version_string;
         char    *failed_choice;
@@ -198,6 +207,11 @@ int	 kexecdh_server(struct ssh *);
 int      kexc25519_client(struct ssh *);
 int      kexc25519_server(struct ssh *);
 
+#ifdef GSSAPI
+int      kexgss_client(struct ssh *);
+int      kexgss_server(struct ssh *);
+#endif
+
 int      kex_dh_hash(int, const char *, const char *,
     const u_char *, size_t, const u_char *, size_t, const u_char *, size_t,
     const BIGNUM *, const BIGNUM *, const BIGNUM *, u_char *, size_t *);