From f4ebe1408e0bc67abfbfb5f0ca2ea13803b36726 Mon Sep 17 00:00:00 2001
From: Sumit Bose <sbose@redhat.com>
Date: Wed, 8 Nov 2023 14:50:24 +0100
Subject: [PATCH] ad-gpo: use hash to store intermediate results
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Currently after the evaluation of a single GPO file the intermediate
results are stored in the cache and this cache entry is updated until
all applicable GPO files are evaluated. Finally the data in the cache is
used to make the decision of access is granted or rejected.

If there are two or more access-control request running in parallel one
request might overwrite the cache object with intermediate data while
another request reads the cached data for the access decision and as a
result will do this decision based on intermediate data.

To avoid this the intermediate results are not stored in the cache
anymore but in hash tables which are specific to the request. Only the
final result is written to the cache to have it available for offline
authentication.

Reviewed-by: Alexey Tikhonov <atikhono@redhat.com>
Reviewed-by: Tomáš Halman <thalman@redhat.com>
(cherry picked from commit d7db7971682da2dbf7642ac94940d6b0577ec35a)

Reference：https://github.com/SSSD/sssd/commit/f4ebe1408e0bc67abfbfb5f0ca2ea13803b36726
Conflict: src/providers/ad/ad_gpo.c
---
 src/providers/ad/ad_gpo.c | 116 +++++++++++++++++++++++++++++++++-----
 1 file changed, 102 insertions(+), 14 deletions(-)

diff --git a/src/providers/ad/ad_gpo.c b/src/providers/ad/ad_gpo.c
index 4d12ef7806..f272131059 100644
--- a/src/providers/ad/ad_gpo.c
+++ b/src/providers/ad/ad_gpo.c
@@ -1356,6 +1356,33 @@ ad_gpo_extract_policy_setting(TALLOC_CTX *mem_ctx,
     return ret;
 }
 
+static errno_t
+add_result_to_hash(hash_table_t *hash, const char *key, char *value)
+{
+    int hret;
+    hash_key_t k;
+    hash_value_t v;
+
+    if (hash == NULL || key == NULL || value == NULL) {
+        return EINVAL;
+    }
+
+    k.type = HASH_KEY_CONST_STRING;
+    k.c_str = key;
+
+    v.type = HASH_VALUE_PTR;
+    v.ptr = value;
+
+    hret = hash_enter(hash, &k, &v);
+    if (hret != HASH_SUCCESS) {
+        DEBUG(SSSDBG_OP_FAILURE, "Failed to add [%s][%s] to hash: [%s].\n",
+                                 key, value, hash_error_string(hret));
+        return EIO;
+    }
+
+    return EOK;
+}
+
 /*
  * This function parses the cse-specific (GP_EXT_GUID_SECURITY) filename,
  * and stores the allow_key and deny_key of all of the gpo_map_types present
@@ -1363,6 +1390,7 @@ ad_gpo_extract_policy_setting(TALLOC_CTX *mem_ctx,
  */
 static errno_t
 ad_gpo_store_policy_settings(struct sss_domain_info *domain,
+                             hash_table_t *allow_maps, hash_table_t *deny_maps,
                              const char *filename)
 {
     struct ini_cfgfile *file_ctx = NULL;
@@ -1496,14 +1524,14 @@ ad_gpo_store_policy_settings(struct sss_domain_info *domain,
                 goto done;
             } else if (ret != ENOENT) {
                 const char *value = allow_value ? allow_value : empty_val;
-                ret = sysdb_gpo_store_gpo_result_setting(domain,
-                                                         allow_key,
-                                                         value);
+                ret = add_result_to_hash(allow_maps, allow_key,
+                                         talloc_strdup(allow_maps, value));
                 if (ret != EOK) {
-                    DEBUG(SSSDBG_CRIT_FAILURE,
-                          "sysdb_gpo_store_gpo_result_setting failed for key:"
-                          "'%s' value:'%s' [%d][%s]\n", allow_key, allow_value,
-                          ret, sss_strerror(ret));
+                    DEBUG(SSSDBG_CRIT_FAILURE, "Failed to add key: [%s] "
+                                               "value: [%s] to allow maps "
+                                               "[%d][%s].\n",
+                                               allow_key, value, ret,
+                                               sss_strerror(ret));
                     goto done;
                 }
             }
@@ -1523,14 +1551,14 @@ ad_gpo_store_policy_settings(struct sss_domain_info *domain,
                 goto done;
             } else if (ret != ENOENT) {
                 const char *value = deny_value ? deny_value : empty_val;
-                ret = sysdb_gpo_store_gpo_result_setting(domain,
-                                                         deny_key,
-                                                         value);
+                ret = add_result_to_hash(deny_maps, deny_key,
+                                         talloc_strdup(deny_maps, value));
                 if (ret != EOK) {
-                    DEBUG(SSSDBG_CRIT_FAILURE,
-                          "sysdb_gpo_store_gpo_result_setting failed for key:"
-                          "'%s' value:'%s' [%d][%s]\n", deny_key, deny_value,
-                          ret, sss_strerror(ret));
+                    DEBUG(SSSDBG_CRIT_FAILURE, "Failed to add key: [%s] "
+                                               "value: [%s] to deny maps "
+                                               "[%d][%s].\n",
+                                               deny_key, value, ret,
+                                               sss_strerror(ret));
                     goto done;
                 }
             }
@@ -1825,6 +1853,8 @@ struct ad_gpo_access_state {
     int num_cse_filtered_gpos;
     int cse_gpo_index;
     const char *ad_domain;
+    hash_table_t *allow_maps;
+    hash_table_t *deny_maps;
 };
 
 static void ad_gpo_connect_done(struct tevent_req *subreq);
@@ -1946,6 +1976,19 @@ ad_gpo_access_send(TALLOC_CTX *mem_ctx,
         goto immediately;
     }
 
+    ret = sss_hash_create(state, 0, &state->allow_maps);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE, "Could not create allow maps "
+              "hash table [%d]: %s\n", ret, sss_strerror(ret));
+        goto immediately;
+    }
+
+    ret = sss_hash_create(state, 0, &state->deny_maps);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE, "Could not create deny maps "
+              "hash table [%d]: %s\n", ret, sss_strerror(ret));
+        goto immediately;
+    }
 
     subreq = sdap_id_op_connect_send(state->sdap_op, state, &ret);
     if (subreq == NULL) {
@@ -2632,6 +2675,43 @@ ad_gpo_cse_step(struct tevent_req *req)
     return EAGAIN;
 }
 
+static errno_t
+store_hash_maps_in_cache(struct sss_domain_info *domain,
+                         hash_table_t *allow_maps, hash_table_t *deny_maps)
+{
+    int ret;
+    struct hash_iter_context_t *iter;
+    hash_entry_t *entry;
+    size_t c;
+    hash_table_t *hash_list[] = { allow_maps, deny_maps, NULL};
+
+
+    for (c = 0; hash_list[c] != NULL; c++) {
+        iter = new_hash_iter_context(hash_list[c]);
+        if (iter == NULL) {
+            DEBUG(SSSDBG_OP_FAILURE, "Failed to create hash iterator.\n");
+            return EINVAL;
+        }
+
+        while ((entry = iter->next(iter)) != NULL) {
+            ret = sysdb_gpo_store_gpo_result_setting(domain,
+                                                     entry->key.c_str,
+                                                     entry->value.ptr);
+            if (ret != EOK) {
+                free(iter);
+                DEBUG(SSSDBG_OP_FAILURE,
+                      "sysdb_gpo_store_gpo_result_setting failed for key:"
+                      "[%s] value:[%s] [%d][%s]\n", entry->key.c_str,
+                      (char *) entry->value.ptr, ret, sss_strerror(ret));
+                return ret;
+            }
+        }
+        talloc_free(iter);
+    }
+
+    return EOK;
+}
+
 /*
  * This cse-specific function (GP_EXT_GUID_SECURITY) increments the
  * cse_gpo_index until the policy settings for all applicable GPOs have been
@@ -2673,6 +2753,7 @@ ad_gpo_cse_done(struct tevent_req *subreq)
      * (as part of the GPO Result object in the sysdb cache).
      */
     ret = ad_gpo_store_policy_settings(state->host_domain,
+                                       state->allow_maps, state->deny_maps,
                                        cse_filtered_gpo->policy_filename);
     if (ret != EOK) {
         DEBUG(SSSDBG_OP_FAILURE,
@@ -2686,6 +2767,13 @@ ad_gpo_cse_done(struct tevent_req *subreq)
 
     if (ret == EOK) {
         /* ret is EOK only after all GPO policy files have been downloaded */
+        ret = store_hash_maps_in_cache(state->host_domain,
+                                       state->allow_maps, state->deny_maps);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_OP_FAILURE, "Failed to store evaluated GPO maps "
+                                     "[%d][%s].\n", ret, sss_strerror(ret));
+            goto done;
+        }
         ret = ad_gpo_perform_hbac_processing(state,
                                              state->gpo_mode,
                                              state->gpo_map_type,
