1 files changed, 171 insertions, 15 deletions

diff --git a/gss-serv.c b/gss-serv.c
index b5d4bb2d1..55f4d4bda 100644
--- a/gss-serv.c
+++ b/gss-serv.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: gss-serv.c,v 1.32 2020/03/13 03:17:07 djm Exp $ */
 
 /*
- * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -44,17 +44,19 @@
 #include "session.h"
 #include "misc.h"
 #include "servconf.h"
+#include "uidswap.h"
 
 #include "ssh-gss.h"
+#include "monitor_wrap.h"
 
 extern ServerOptions options;
 
 static ssh_gssapi_client gssapi_client =
-    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
-    GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}};
+    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, GSS_C_NO_CREDENTIAL,
+    GSS_C_NO_NAME, NULL, {NULL, NULL, NULL, NULL, NULL}, 0, 0};
 
 ssh_gssapi_mech gssapi_null_mech =
-    { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
+    { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL};
 
 #ifdef KRB5
 extern ssh_gssapi_mech gssapi_kerberos_mech;
@@ -141,6 +143,29 @@ ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
 }
 
 /* Unprivileged */
+char *
+ssh_gssapi_server_mechanisms(void) {
+        if (supported_oids == NULL)
+                ssh_gssapi_prepare_supported_oids();
+        return (ssh_gssapi_kex_mechs(supported_oids,
+            &ssh_gssapi_server_check_mech, NULL, NULL,
+            options.gss_kex_algorithms));
+}
+
+/* Unprivileged */
+int
+ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data,
+    const char *dummy) {
+        Gssctxt *ctx = NULL;
+        int res;
+
+        res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
+        ssh_gssapi_delete_ctx(&ctx);
+
+        return (res);
+}
+
+/* Unprivileged */
 void
 ssh_gssapi_supported_oids(gss_OID_set *oidset)
 {
@@ -150,7 +175,9 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset)
         gss_OID_set supported;
 
         gss_create_empty_oid_set(&min_status, oidset);
-        gss_indicate_mechs(&min_status, &supported);
+
+        if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported)))
+                return;
 
         while (supported_mechs[i]->name != NULL) {
                 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
@@ -276,8 +303,48 @@ OM_uint32
 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
 {
         int i = 0;
+        int equal = 0;
+        gss_name_t new_name = GSS_C_NO_NAME;
+        gss_buffer_desc ename = GSS_C_EMPTY_BUFFER;
+
+        if (options.gss_store_rekey && client->used && ctx->client_creds) {
+                if (client->mech->oid.length != ctx->oid->length ||
+                    (memcmp(client->mech->oid.elements,
+                     ctx->oid->elements, ctx->oid->length) !=0)) {
+                        debug("Rekeyed credentials have different mechanism");
+                        return GSS_S_COMPLETE;
+                }
+
+                if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
+                    ctx->client_creds, ctx->oid, &new_name,
+                    NULL, NULL, NULL))) {
+                        ssh_gssapi_error(ctx);
+                        return (ctx->major);
+                }
+
+                ctx->major = gss_compare_name(&ctx->minor, client->name,
+                    new_name, &equal);
+
+                if (GSS_ERROR(ctx->major)) {
+                        ssh_gssapi_error(ctx);
+                        return (ctx->major);
+                }
+
+                if (!equal) {
+                        debug("Rekeyed credentials have different name");
+                        return GSS_S_COMPLETE;
+                }
 
-        gss_buffer_desc ename;
+                debug("Marking rekeyed credentials for export");
+
+                gss_release_name(&ctx->minor, &client->name);
+                gss_release_cred(&ctx->minor, &client->creds);
+                client->name = new_name;
+                client->creds = ctx->client_creds;
+                ctx->client_creds = GSS_C_NO_CREDENTIAL;
+                client->updated = 1;
+                return GSS_S_COMPLETE;
+        }
 
         client->mech = NULL;
 
@@ -292,6 +359,13 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
         if (client->mech == NULL)
                 return GSS_S_FAILURE;
 
+        if (ctx->client_creds &&
+            (ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
+             ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) {
+                ssh_gssapi_error(ctx);
+                return (ctx->major);
+        }
+
         if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
             &client->displayname, NULL))) {
                 ssh_gssapi_error(ctx);
@@ -309,6 +383,8 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
                 return (ctx->major);
         }
 
+        gss_release_buffer(&ctx->minor, &ename);
+
         /* We can't copy this structure, so we just move the pointer to it */
         client->creds = ctx->client_creds;
         ctx->client_creds = GSS_C_NO_CREDENTIAL;
@@ -356,19 +432,23 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep)
 
 /* Privileged */
 int
-ssh_gssapi_userok(char *user)
+ssh_gssapi_userok(char *user, struct passwd *pw, int kex)
 {
         OM_uint32 lmin;
 
+        (void) kex; /* used in privilege separation */
+
         if (gssapi_client.exportedname.length == 0 ||
             gssapi_client.exportedname.value == NULL) {
                 debug("No suitable client data");
                 return 0;
         }
         if (gssapi_client.mech && gssapi_client.mech->userok)
-                if ((*gssapi_client.mech->userok)(&gssapi_client, user))
+                if ((*gssapi_client.mech->userok)(&gssapi_client, user)) {
+                        gssapi_client.used = 1;
+                        gssapi_client.store.owner = pw;
                         return 1;
-                else {
+                } else {
                         /* Destroy delegated credentials if userok fails */
                         gss_release_buffer(&lmin, &gssapi_client.displayname);
                         gss_release_buffer(&lmin, &gssapi_client.exportedname);
@@ -382,14 +462,90 @@ ssh_gssapi_userok(char *user)
         return (0);
 }
 
-/* Privileged */
-OM_uint32
-ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+/* These bits are only used for rekeying. The unpriviledged child is running
+ * as the user, the monitor is root.
+ *
+ * In the child, we want to :
+ *    *) Ask the monitor to store our credentials into the store we specify
+ *    *) If it succeeds, maybe do a PAM update
+ */
+
+/* Stuff for PAM */
+
+#ifdef USE_PAM
+static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg,
+    struct pam_response **resp, void *data)
 {
-        ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
-            gssbuf, gssmic, NULL);
+        return (PAM_CONV_ERR);
+}
+#endif
 
-        return (ctx->major);
+void
+ssh_gssapi_rekey_creds(void) {
+        int ok;
+#ifdef USE_PAM
+        int ret;
+        pam_handle_t *pamh = NULL;
+        struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL};
+        char *envstr;
+#endif
+
+        if (gssapi_client.store.filename == NULL &&
+            gssapi_client.store.envval == NULL &&
+            gssapi_client.store.envvar == NULL)
+                return;
+
+        ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));
+
+        if (!ok)
+                return;
+
+        debug("Rekeyed credentials stored successfully");
+
+        /* Actually managing to play with the ssh pam stack from here will
+         * be next to impossible. In any case, we may want different options
+         * for rekeying. So, use our own :)
+         */
+#ifdef USE_PAM  
+        if (!use_privsep) {
+                debug("Not even going to try and do PAM with privsep disabled");
+                return;
+        }
+
+        ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name,
+            &pamconv, &pamh);
+        if (ret)
+                return;
+
+        xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar,
+            gssapi_client.store.envval);
+
+        ret = pam_putenv(pamh, envstr);
+        if (!ret)
+                pam_setcred(pamh, PAM_REINITIALIZE_CRED);
+        pam_end(pamh, PAM_SUCCESS);
+#endif
+}
+
+int
+ssh_gssapi_update_creds(ssh_gssapi_ccache *store) {
+        int ok = 0;
+
+        /* Check we've got credentials to store */
+        if (!gssapi_client.updated)
+                return 0;
+
+        gssapi_client.updated = 0;
+
+        temporarily_use_uid(gssapi_client.store.owner);
+        if (gssapi_client.mech && gssapi_client.mech->updatecreds)
+                ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client);
+        else
+                debug("No update function for this mechanism");
+
+        restore_uid();
+
+        return ok;
 }
 
 /* Privileged */