* Add remaining pieces of Kerberos support (closes: #275472):

  - Add GSSAPI key exchange support from
    http://www.sxw.org.uk/computing/patches/openssh.html (thanks, Stephen
    Frost).

1 files changed, 53 insertions, 5 deletions

diff --git a/sshd.c b/sshd.c
index 86468318e..967f5e7f0 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1122,10 +1122,12 @@ main(int ac, char **av)
                 logit("Disabling protocol version 1. Could not load host key");
                 options.protocol &= ~SSH_PROTO_1;
         }
+#ifndef GSSAPI
         if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
                 logit("Disabling protocol version 2. Could not load host key");
                 options.protocol &= ~SSH_PROTO_2;
         }
+#endif
         if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
                 logit("sshd: no hostkeys available -- exiting.");
                 exit(1);
@@ -2011,13 +2013,59 @@ do_ssh2_kex(void)
         myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
 
         /* start key exchange */
-        kex = kex_setup(myproposal);
-        kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+  
+#ifdef GSSAPI
+        {
+        char *orig;
+        char *gss = NULL;
+        char *newstr = NULL;
+        orig = myproposal[PROPOSAL_KEX_ALGS];
+
+        /* 
+         * If we don't have a host key, then there's no point advertising
+         * the other key exchange algorithms
+         */
+
+        if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
+                orig = NULL;
+
+        gss = ssh_gssapi_server_mechanisms();
+
+        if (gss && orig) {
+                int len = strlen(orig) + strlen(gss) + 2;
+                newstr = xmalloc(len);
+                snprintf(newstr, len, "%s,%s", gss, orig);
+        } else if (gss) {
+                newstr = gss;
+        } else if (orig) {
+                newstr = orig;
+        }
+        /* 
+         * If we've got GSSAPI mechanisms, then we've got the 'null' host
+         * key alg, but we can't tell people about it unless its the only
+         * host key algorithm we support
+         */
+        if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
+                myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
+
+        if (newstr)
+                myproposal[PROPOSAL_KEX_ALGS] = newstr;
+        else
+                fatal("No supported key exchange algorithms");
+        }
+#endif
+
+        /* start key exchange */
+        kex = kex_setup(myproposal);
+        kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
         kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
-        kex->server = 1;
-        kex->client_version_string=client_version_string;
-        kex->server_version_string=server_version_string;
+#ifdef GSSAPI
+        kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
+#endif
+        kex->server = 1;
+        kex->client_version_string=client_version_string;
+        kex->server_version_string=server_version_string;
         kex->load_host_key=&get_hostkey_by_type;
         kex->host_key_index=&get_hostkey_index;