Modify priority evaluation in SELinux user maps

The functionality now is following:

When rule is being matched, its priority is determined as a combination
of user and host specificity (host taking preference).

After the rule is matched in provider, only its host priority is stored
in sysdb for later usage.

When rules are matched in the responder, their user priority is
determined. After that their host priority is retrieved directly from
sysdb and sum of both priorities is user to determine whether to use
that rule or not. If more rules have the same priority, the order given
in IPA config is used.

https://fedorahosted.org/sssd/ticket/1360
https://fedorahosted.org/sssd/ticket/1395

5 files changed, 113 insertions, 9 deletions

diff --git a/src/db/sysdb.h b/src/db/sysdb.h
index 5baac98b..3c6166cf 100644
--- a/src/db/sysdb.h
+++ b/src/db/sysdb.h
@@ -120,6 +120,7 @@
 #define SYSDB_SELINUX_SEEALSO "seeAlso"
 #define SYSDB_SELINUX_USER "selinuxUser"
 #define SYSDB_SELINUX_ENABLED "enabled"
+#define SYSDB_SELINUX_HOST_PRIORITY "hostPriority"
 
 #define SYSDB_CACHEDPWD "cachedPassword"
 
diff --git a/src/db/sysdb_selinux.c b/src/db/sysdb_selinux.c
index e9f2da11..8e69cd3e 100644
--- a/src/db/sysdb_selinux.c
+++ b/src/db/sysdb_selinux.c
@@ -341,6 +341,7 @@ errno_t sysdb_search_selinux_usermap_by_username(TALLOC_CTX *mem_ctx,
                             SYSDB_HOST_CATEGORY,
                             SYSDB_ORIG_MEMBER_USER,
                             SYSDB_ORIG_MEMBER_HOST,
+                            SYSDB_SELINUX_HOST_PRIORITY,
                             SYSDB_SELINUX_USER,
                             NULL };
     struct ldb_message **msgs = NULL;
@@ -351,6 +352,9 @@ errno_t sysdb_search_selinux_usermap_by_username(TALLOC_CTX *mem_ctx,
     struct ldb_dn *basedn;
     size_t msgs_count = 0;
     size_t usermaps_cnt;
+    uint32_t priority = 0;
+    uint32_t host_priority = 0;
+    uint32_t top_priority = 0;
     char *filter;
     errno_t ret;
     int i;
@@ -405,7 +409,35 @@ errno_t sysdb_search_selinux_usermap_by_username(TALLOC_CTX *mem_ctx,
         tmp_attrs->a = msgs[i]->elements;
         tmp_attrs->num = msgs[i]->num_elements;
 
-        if (sss_selinux_match(tmp_attrs, user, NULL)) {
+        if (sss_selinux_match(tmp_attrs, user, NULL, &priority)) {
+            priority &= ~(SELINUX_PRIORITY_HOST_NAME |
+                          SELINUX_PRIORITY_HOST_GROUP |
+                          SELINUX_PRIORITY_HOST_CAT);
+
+            /* Now figure out host priority */
+            ret = sysdb_attrs_get_uint32_t(tmp_attrs,
+                                           SYSDB_SELINUX_HOST_PRIORITY,
+                                           &host_priority);
+            if (ret != EOK) {
+                continue;
+            }
+
+            priority += host_priority;
+            if (priority < top_priority) {
+                /* This rule has lower priority than what we already have,
+                 * skip it */
+                continue;
+            } else if (priority > top_priority) {
+                /* If the rule has higher priority, drop what we already
+                 * have */
+                while (usermaps_cnt > 0) {
+                    usermaps_cnt--;
+                    talloc_zfree(usermaps[usermaps_cnt]);
+                }
+                top_priority = priority;
+            }
+
+
             usermaps[usermaps_cnt] = talloc_steal(usermaps, msgs[i]);
             usermaps_cnt++;
         } else {
diff --git a/src/providers/ipa/ipa_session.c b/src/providers/ipa/ipa_session.c
index 238acdde..12e80729 100644
--- a/src/providers/ipa/ipa_session.c
+++ b/src/providers/ipa/ipa_session.c
@@ -326,6 +326,7 @@ static void ipa_get_selinux_maps_done(struct tevent_req *subreq)
     const char *tmp_str;
     size_t conf_cnt = 0;
     size_t pos_cnt = 0;
+    uint32_t priority = 0;
     errno_t ret;
     int i;
 
@@ -358,7 +359,17 @@ static void ipa_get_selinux_maps_done(struct tevent_req *subreq)
     }
 
     for (i = 0; i < count; i++) {
-        if (sss_selinux_match(results[i], state->user, state->host)) {
+        if (sss_selinux_match(results[i], state->user, state->host, &priority)) {
+            priority &= ~(SELINUX_PRIORITY_USER_NAME |
+                          SELINUX_PRIORITY_USER_GROUP |
+                          SELINUX_PRIORITY_USER_CAT);
+            ret = sysdb_attrs_add_uint32(results[i],
+                                         SYSDB_SELINUX_HOST_PRIORITY,
+                                         priority);
+            if (ret != EOK) {
+                goto done;
+            }
+
             state->confirmed_match[conf_cnt] = talloc_steal(state->confirmed_match,
                                                             results[i]);
             conf_cnt++;
@@ -445,6 +456,7 @@ static void ipa_get_selinux_hbac_done(struct tevent_req *subreq)
     size_t rule_count;
     size_t conf_cnt;
     size_t pos_cnt;
+    uint32_t priority = 0;
     errno_t ret;
     int i, j;
 
@@ -458,7 +470,7 @@ static void ipa_get_selinux_hbac_done(struct tevent_req *subreq)
     for (pos_cnt = 0 ; state->possible_match[pos_cnt]; pos_cnt++) ;
 
     for (i = 0; i < rule_count; i++) {
-        if (!sss_selinux_match(rules[i], state->user, state->host)) {
+        if (!sss_selinux_match(rules[i], state->user, state->host, &priority)) {
             continue;
         }
 
@@ -480,6 +492,26 @@ static void ipa_get_selinux_hbac_done(struct tevent_req *subreq)
             }
 
             if (strcasecmp(hbac_dn, seealso_dn) == 0) {
+                priority &= ~(SELINUX_PRIORITY_USER_NAME |
+                              SELINUX_PRIORITY_USER_GROUP |
+                              SELINUX_PRIORITY_USER_CAT);
+                ret = sysdb_attrs_add_uint32(usermap,
+                                             SYSDB_SELINUX_HOST_PRIORITY,
+                                             priority);
+                if (ret != EOK) {
+                    goto done;
+                }
+
+                ret = sysdb_attrs_copy_values(rules[i], usermap, SYSDB_ORIG_MEMBER_USER);
+                if (ret != EOK) {
+                    goto done;
+                }
+
+                ret = sysdb_attrs_copy_values(rules[i], usermap, SYSDB_USER_CATEGORY);
+                if (ret != EOK) {
+                    goto done;
+                }
+
                 state->confirmed_match[conf_cnt++] = talloc_steal(
                                                         state->confirmed_match,
                                                         usermap);
diff --git a/src/util/sss_selinux.c b/src/util/sss_selinux.c
index bdb11795..7b2417bb 100644
--- a/src/util/sss_selinux.c
+++ b/src/util/sss_selinux.c
@@ -49,7 +49,8 @@ static bool match_entity(struct ldb_message_element *values,
 
 bool sss_selinux_match(struct sysdb_attrs *usermap,
                        struct sysdb_attrs *user,
-                       struct sysdb_attrs *host)
+                       struct sysdb_attrs *host,
+                       uint32_t *_priority)
 {
     struct ldb_message_element *users_el = NULL;
     struct ldb_message_element *usercat = NULL;
@@ -58,6 +59,9 @@ bool sss_selinux_match(struct sysdb_attrs *usermap,
     struct ldb_message_element *dn;
     struct ldb_message_element *memberof;
     int i;
+    uint32_t priority = 0;
+    bool matched_name;
+    bool matched_group;
     errno_t ret;
 
     if (usermap == NULL) {
@@ -90,10 +94,21 @@ bool sss_selinux_match(struct sysdb_attrs *usermap,
          */
         if (usercat == NULL || usercat->num_values == 0 ||
             strcasecmp((char *)usercat->values[0].data, "all") != 0) {
-            if (users_el == NULL || (!match_entity(users_el, dn) &&
-                !match_entity(users_el, memberof))) {
+            if (users_el == NULL) {
                 return false;
+            } else {
+                matched_name = match_entity(users_el, dn);
+                matched_group = match_entity(users_el, memberof);
+                if (matched_name) {
+                    priority |= SELINUX_PRIORITY_USER_NAME;
+                } else if (matched_group) {
+                    priority |= SELINUX_PRIORITY_USER_GROUP;
+                } else {
+                    return false;
+                }
             }
+        } else {
+            priority |= SELINUX_PRIORITY_USER_CAT;
         }
     }
 
@@ -109,11 +124,26 @@ bool sss_selinux_match(struct sysdb_attrs *usermap,
          */
         if (hostcat == NULL || hostcat->num_values == 0 ||
             strcasecmp((char *)hostcat->values[0].data, "all") != 0) {
-            if (hosts_el == NULL || (!match_entity(hosts_el, dn) &&
-                !match_entity(hosts_el, memberof))) {
+            if (hosts_el == NULL) {
                 return false;
+            } else {
+                matched_name = match_entity(hosts_el, dn);
+                matched_group = match_entity(hosts_el, memberof);
+                if (matched_name) {
+                    priority |= SELINUX_PRIORITY_HOST_NAME;
+                } else if (matched_group) {
+                    priority |= SELINUX_PRIORITY_HOST_GROUP;
+                } else {
+                    return false;
+                }
             }
         }
+    } else {
+        priority |= SELINUX_PRIORITY_HOST_CAT;
+    }
+
+    if (_priority != NULL) {
+        *_priority = priority;
     }
 
     return true;
diff --git a/src/util/sss_selinux.h b/src/util/sss_selinux.h
index 11a5445e..def38940 100644
--- a/src/util/sss_selinux.h
+++ b/src/util/sss_selinux.h
@@ -30,6 +30,14 @@
 
 #include <db/sysdb.h>
 
+#define SELINUX_PRIORITY_USER_CAT 1
+#define SELINUX_PRIORITY_USER_GROUP 2
+#define SELINUX_PRIORITY_USER_NAME 4
+/* According to specification, host has higher priority */
+#define SELINUX_PRIORITY_HOST_CAT 8
+#define SELINUX_PRIORITY_HOST_GROUP 16
+#define SELINUX_PRIORITY_HOST_NAME 32
+
 errno_t
 sss_selinux_extract_user(TALLOC_CTX *mem_ctx,
                          struct sysdb_ctx *sysdb,
@@ -38,7 +46,8 @@ sss_selinux_extract_user(TALLOC_CTX *mem_ctx,
 
 bool sss_selinux_match(struct sysdb_attrs *usermap,
                        struct sysdb_attrs *user,
-                       struct sysdb_attrs *host);
+                       struct sysdb_attrs *host,
+                       uint32_t *_priority);
 
 const char *sss_selinux_map_get_seuser(struct ldb_message *usermap);