Add HBAC evaluator and tests

3 files changed, 386 insertions, 0 deletions

diff --git a/src/providers/ipa/hbac_evaluator.c b/src/providers/ipa/hbac_evaluator.c
new file mode 100644
index 00000000..949f0aef
--- /dev/null
+++ b/src/providers/ipa/hbac_evaluator.c
@@ -0,0 +1,221 @@
+/*
+    SSSD
+
+    IPA Backend Module -- Access control
+
+    Authors:
+        Sumit Bose <sbose@redhat.com>
+        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 <stdlib.h>
+#include <string.h>
+#include "providers/ipa/ipa_hbac.h"
+
+/* Placeholder structure for future HBAC time-based
+ * evaluation rules
+ */
+struct hbac_time_rules {
+    int not_yet_implemented;
+};
+
+enum hbac_eval_result_int {
+    HBAC_EVAL_MATCH_ERROR = -1,
+    HBAC_EVAL_MATCHED,
+    HBAC_EVAL_UNMATCHED
+};
+
+enum hbac_eval_result_int hbac_evaluate_rule(struct hbac_rule *rule,
+                                             struct hbac_eval_req *hbac_req,
+                                             enum hbac_error_code *error);
+
+enum hbac_eval_result hbac_evaluate(struct hbac_rule **rules,
+                                    struct hbac_eval_req *hbac_req,
+                                    struct hbac_info **info)
+{
+    enum hbac_error_code ret;
+    enum hbac_eval_result result = HBAC_EVAL_DENY;
+    enum hbac_eval_result_int intermediate_result;
+
+    if (info) {
+        *info = malloc(sizeof(struct hbac_info));
+        if (!*info) {
+            return HBAC_EVAL_OOM;
+        }
+        (*info)->code = HBAC_ERROR_UNKNOWN;
+        (*info)->rule_name = NULL;
+    }
+    uint32_t i;
+
+    for (i = 0; rules[i]; i++) {
+        intermediate_result = hbac_evaluate_rule(rules[i], hbac_req, &ret);
+        if (intermediate_result == HBAC_EVAL_UNMATCHED) {
+            /* This rule did not match at all. Skip it */
+            continue;
+        } else if (intermediate_result == HBAC_EVAL_MATCHED) {
+            /* This request matched an ALLOW rule
+             * Set the result to ALLOW but continue checking
+             * the other rules in case a DENY rule trumps it.
+             */
+            result = HBAC_EVAL_ALLOW;
+            if (info) {
+                (*info)->code = HBAC_SUCCESS;
+                (*info)->rule_name = strdup(rules[i]->name);
+                if (!(*info)->rule_name) {
+                    result = HBAC_EVAL_ERROR;
+                    (*info)->code = HBAC_ERROR_OUT_OF_MEMORY;
+                }
+            }
+            break;
+        } else {
+            /* An error occurred processing this rule */
+            result = HBAC_EVAL_ERROR;
+            (*info)->code = ret;
+            (*info)->rule_name = strdup(rules[i]->name);
+            /* Explicitly not checking the result of strdup(), since if
+             * it's NULL, we can't do anything anyway.
+             */
+            goto done;
+        }
+    }
+
+    /* If we've reached the end of the loop, we have either set the
+     * result to ALLOW explicitly or we'll stick with the default DENY.
+     */
+done:
+
+    return result;
+}
+
+static bool hbac_evaluate_element(struct hbac_rule_element *rule_el,
+                                  struct hbac_request_element *req_el);
+
+enum hbac_eval_result_int hbac_evaluate_rule(struct hbac_rule *rule,
+                                             struct hbac_eval_req *hbac_req,
+                                             enum hbac_error_code *error)
+{
+    if (!rule->enabled) return HBAC_EVAL_UNMATCHED;
+
+    /* Make sure we have all elements */
+    if (!rule->users
+     || !rule->services
+     || !rule->targethosts
+     || !rule->srchosts) {
+        *error = HBAC_ERROR_UNPARSEABLE_RULE;
+        return HBAC_EVAL_MATCH_ERROR;
+    }
+
+    /* Check users */
+    if (!hbac_evaluate_element(rule->users, hbac_req->user)) {
+        return HBAC_EVAL_UNMATCHED;
+    }
+
+    /* Check services */
+    if (!hbac_evaluate_element(rule->services, hbac_req->service)) {
+        return HBAC_EVAL_UNMATCHED;
+    }
+
+    /* Check target hosts */
+    if (!hbac_evaluate_element(rule->targethosts, hbac_req->targethost)) {
+        return HBAC_EVAL_UNMATCHED;
+    }
+
+    /* Check source hosts */
+    if (!hbac_evaluate_element(rule->srchosts, hbac_req->srchost)) {
+        return HBAC_EVAL_UNMATCHED;
+    }
+
+    return HBAC_EVAL_MATCHED;
+}
+
+static bool hbac_evaluate_element(struct hbac_rule_element *rule_el,
+                                  struct hbac_request_element *req_el)
+{
+    size_t i, j;
+
+    if (rule_el->category & HBAC_CATEGORY_ALL) {
+        return true;
+    }
+
+    /* First check the name list */
+    if (rule_el->names) {
+        for (i = 0; rule_el->names[i]; i++) {
+            if (strcmp(rule_el->names[i], req_el->name) == 0) {
+                return true;
+            }
+        }
+    }
+
+    if (rule_el->groups) {
+        /* Not found in the name list
+         * Check for group membership
+         */
+        for (i = 0; rule_el->groups[i]; i++) {
+            for (j = 0; req_el->groups[j]; j++) {
+                if (strcmp(rule_el->groups[i],
+                           req_el->groups[j]) == 0) {
+                    return true;
+                }
+            }
+        }
+    }
+
+    /* Not found in groups either */
+    return false;
+}
+
+const char *hbac_result_string(enum hbac_eval_result result)
+{
+    switch(result) {
+    case HBAC_EVAL_ALLOW:
+        return "HBAC_EVAL_ALLOW";
+    case HBAC_EVAL_DENY:
+        return "HBAC_EVAL_DENY";
+    case HBAC_EVAL_ERROR:
+        return "HBAC_EVAL_ERROR";
+    case HBAC_EVAL_OOM:
+        return "Could not allocate memory for hbac_info object";
+    }
+    return "HBAC_EVAL_ERROR";
+}
+
+void hbac_free_info(struct hbac_info *info)
+{
+    if (info == NULL) return;
+
+    free(info->rule_name);
+    free(info);
+    info = NULL;
+}
+
+const char *hbac_error_string(enum hbac_error_code code)
+{
+    switch(code) {
+    case HBAC_SUCCESS:
+        return "Success";
+    case HBAC_ERROR_NOT_IMPLEMENTED:
+        return "Function is not yet implemented";
+    case HBAC_ERROR_OUT_OF_MEMORY:
+        return "Out of memory";
+    case HBAC_ERROR_UNPARSEABLE_RULE:
+        return "Rule could not be evaluated";
+    case HBAC_ERROR_UNKNOWN:
+    default:
+        return "Unknown error code";
+    }
+}
diff --git a/src/providers/ipa/ipa_hbac.h b/src/providers/ipa/ipa_hbac.h
new file mode 100644
index 00000000..a1d51378
--- /dev/null
+++ b/src/providers/ipa/ipa_hbac.h
@@ -0,0 +1,154 @@
+/*
+    SSSD
+
+    IPA Backend Module -- Access control
+
+    Authors:
+        Sumit Bose <sbose@redhat.com>
+        Stephen Gallagher <sgallagh@redhat.com>
+
+    Copyright (C) 2009 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/>.
+*/
+
+#ifndef IPA_HBAC_H_
+#define IPA_HBAC_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+
+enum hbac_eval_result {
+    HBAC_EVAL_ERROR = -1,
+    HBAC_EVAL_ALLOW,
+    HBAC_EVAL_DENY,
+    HBAC_EVAL_OOM
+};
+
+#define HBAC_CATEGORY_NULL 0x0000 /* No service category specified */
+#define HBAC_CATEGORY_ALL  0x0001 /* Rule should apply to all */
+
+/* Opaque type contained in hbac_evaluator.c */
+struct hbac_time_rules;
+
+struct hbac_rule_element {
+    uint32_t category;
+    const char **names;
+    const char **groups;
+};
+
+struct hbac_rule {
+    const char *name;
+    bool enabled;
+
+    /* Services and service groups
+     * for which this rule applies
+     */
+    struct hbac_rule_element *services;
+
+    /* Users and groups for which this
+     * rule applies
+     */
+    struct hbac_rule_element *users;
+
+    /* Target hosts for which this rule apples */
+    struct hbac_rule_element *targethosts;
+
+    /* Source hosts for which this rule applies */
+    struct hbac_rule_element *srchosts;
+
+    /* For future use */
+    struct hbac_time_rules *timerules;
+};
+
+struct hbac_request_element {
+    const char *name;
+    const char **groups;
+};
+
+struct hbac_eval_req {
+    /* This is a list of service DNs to check,
+     * it must consist of the actual service
+     * requested, as well as all parent groups
+     * containing that service.
+     */
+    struct hbac_request_element *service;
+
+    /* This is a list of user DNs to check,
+     * it must consist of the actual user
+     * requested, as well as all parent groups
+     * containing that user.
+     */
+    struct hbac_request_element *user;
+
+    /* This is a list of target hosts to check,
+     * it must consist of the actual target host
+     * requested, as well as all parent groups
+     * containing that target host.
+     */
+    struct hbac_request_element *targethost;
+
+    /* This is a list of source hosts to check,
+     * it must consist of the actual source host
+     * requested, as well as all parent groups
+     * containing that source host.
+     */
+    struct hbac_request_element *srchost;
+
+    /* For future use */
+    time_t request_time;
+};
+
+enum hbac_error_code {
+    HBAC_ERROR_UNKNOWN = -1,
+    HBAC_SUCCESS,
+    HBAC_ERROR_NOT_IMPLEMENTED,
+    HBAC_ERROR_OUT_OF_MEMORY,
+    HBAC_ERROR_UNPARSEABLE_RULE
+};
+
+/* Extended information */
+struct hbac_info {
+    /* If the hbac_eval_result was HBAC_EVAL_ERROR,
+     * this will be an error code.
+     * Otherwise it will be HBAC_SUCCESS
+     */
+    enum hbac_error_code code;
+
+    /* Specify the name of the rule that matched or
+     * threw an error
+     */
+    char *rule_name;
+};
+
+
+/**
+ * @brief Evaluate an authorization request against a set of HBAC rules
+ *
+ * @param[in] rules    A NULL-terminated list of rules to evaluate against
+ * @param[in] hbac_req A user authorization request
+ * @param[out] info    Extended information (including the name of the
+ *                     rule that allowed access (or caused a parse error)
+ * @return
+ */
+enum hbac_eval_result hbac_evaluate(struct hbac_rule **rules,
+                                    struct hbac_eval_req *hbac_req,
+                                    struct hbac_info **info);
+
+const char *hbac_result_string(enum hbac_eval_result result);
+const char *hbac_error_string(enum hbac_error_code code);
+
+void hbac_free_info(struct hbac_info *info);
+
+#endif /* IPA_HBAC_H_ */
diff --git a/src/providers/ipa/ipa_hbac.pc.in b/src/providers/ipa/ipa_hbac.pc.in
new file mode 100644
index 00000000..9d799e85
--- /dev/null
+++ b/src/providers/ipa/ipa_hbac.pc.in
@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: ipa_hbac
+Description: FreeIPA HBAC Evaluator library
+Version: @VERSION@
+Libs: -L$(libdir) -lipa_hbac
+Cflags:
+URL: http://fedorahosted.org/sssd/