PAM: make initgroups timeout work across multiple clients

Instead of timing out the initgroups lookup on a per-cctx basis,
we will maintain a hash table of recently-seen users and use this
instead. This will allow SSSD to handle user's logging into
multiple services simultaneously more graciously, as well as
playing nicer with SSH (which makes calls to PAM both before and
after a fork).

https://fedorahosted.org/sssd/ticket/1063

1 files changed, 153 insertions, 0 deletions

diff --git a/src/responder/pam/pam_helpers.c b/src/responder/pam/pam_helpers.c
new file mode 100644
index 000000000..d2068e57c
--- /dev/null
+++ b/src/responder/pam/pam_helpers.c
@@ -0,0 +1,153 @@
+/*
+    SSSD
+
+    Authors:
+        Stephen Gallagher <sgallagh@redhat.com>
+
+    Copyright (C) 2011 Red Hat
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#include "util/util.h"
+#include "src/responder/pam/pam_helpers.h"
+
+struct pam_initgr_table_ctx {
+    hash_table_t *id_table;
+    char *name;
+};
+
+static void pam_initgr_cache_remove(struct tevent_context *ev,
+                                    struct tevent_timer *te,
+                                    struct timeval tv,
+                                    void *pvt);
+
+errno_t pam_initgr_cache_set(struct tevent_context *ev,
+                             hash_table_t *id_table,
+                             char *name,
+                             long timeout)
+{
+    errno_t ret;
+    hash_key_t key;
+    hash_value_t val;
+    int hret;
+    struct tevent_timer *te;
+    struct timeval tv;
+    struct pam_initgr_table_ctx *table_ctx;
+
+    table_ctx = talloc_zero(id_table, struct pam_initgr_table_ctx);
+    if (!table_ctx) return ENOMEM;
+
+    table_ctx->id_table = id_table;
+    table_ctx->name = talloc_strdup(table_ctx, name);
+    if (!table_ctx->name) {
+        ret = ENOMEM;
+        goto done;
+    }
+
+    key.type = HASH_KEY_STRING;
+    key.str = name;
+
+    /* The value isn't relevant, since we're using
+     * a timer to remove the entry.
+     */
+    val.type = HASH_VALUE_UNDEF;
+
+    hret = hash_enter(id_table, &key, &val);
+    if (hret != HASH_SUCCESS) {
+        DEBUG(SSSDBG_MINOR_FAILURE,
+              ("Could not update initgr cache for [%s]: [%s]\n",
+               name, hash_error_string(hret)));
+        ret = EIO;
+        goto done;
+    } else {
+        DEBUG(SSSDBG_TRACE_INTERNAL,
+              ("[%s] added to PAM initgroup cache\n",
+               name));
+    }
+
+    /* Create a timer event to remove the entry from the cache */
+    tv = tevent_timeval_current_ofs(timeout, 0);
+    te = tevent_add_timer(ev, table_ctx, tv,
+                          pam_initgr_cache_remove,
+                          table_ctx);
+    if (!te) {
+        ret = ENOMEM;
+        goto done;
+    }
+
+    ret = EOK;
+
+done:
+    if (ret != EOK) {
+        talloc_free(table_ctx);
+    }
+    return ret;
+}
+
+static void pam_initgr_cache_remove(struct tevent_context *ev,
+                                    struct tevent_timer *te,
+                                    struct timeval tv,
+                                    void *pvt)
+{
+    int hret;
+    hash_key_t key;
+
+    struct pam_initgr_table_ctx *table_ctx =
+            talloc_get_type(pvt, struct pam_initgr_table_ctx);
+
+    key.type = HASH_KEY_STRING;
+    key.str = table_ctx->name;
+
+    hret = hash_delete(table_ctx->id_table, &key);
+    if (hret != HASH_SUCCESS
+            && hret != HASH_ERROR_KEY_NOT_FOUND) {
+        DEBUG(SSSDBG_MINOR_FAILURE,
+              ("Could not clear [%s] from initgr cache: [%s]\n",
+               table_ctx->name,
+               hash_error_string(hret)));
+    } else {
+        DEBUG(SSSDBG_TRACE_INTERNAL,
+              ("[%s] removed from PAM initgroup cache\n",
+               table_ctx->name));
+    }
+
+    talloc_free(table_ctx);
+}
+
+errno_t pam_initgr_check_timeout(hash_table_t *id_table,
+                                 char *name)
+{
+    hash_key_t key;
+    hash_value_t val;
+    int hret;
+
+    key.type = HASH_KEY_STRING;
+    key.str = name;
+
+    hret = hash_lookup(id_table, &key, &val);
+    if (hret != HASH_SUCCESS
+            && hret != HASH_ERROR_KEY_NOT_FOUND) {
+        return EIO;
+    } else if (hret == HASH_ERROR_KEY_NOT_FOUND) {
+        return ENOENT;
+    }
+
+    /* If there's a value here, then the cache
+     * entry is still valid.
+     */
+    return EOK;
+}
+