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-rw-r--r--security/integrity/ima/ima_policy.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
new file mode 100644
index 00000000000..7c3d1ffb147
--- /dev/null
+++ b/security/integrity/ima/ima_policy.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2008 IBM Corporation
+ * Author: Mimi Zohar <zohar@us.ibm.com>
+ *
+ * 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, version 2 of the License.
+ *
+ * ima_policy.c
+ * - initialize default measure policy rules
+ *
+ */
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/audit.h>
+#include <linux/security.h>
+#include <linux/magic.h>
+
+#include "ima.h"
+
+/* flags definitions */
+#define IMA_FUNC 0x0001
+#define IMA_MASK 0x0002
+#define IMA_FSMAGIC 0x0004
+#define IMA_UID 0x0008
+
+enum ima_action { DONT_MEASURE, MEASURE };
+
+struct ima_measure_rule_entry {
+ struct list_head list;
+ enum ima_action action;
+ unsigned int flags;
+ enum ima_hooks func;
+ int mask;
+ unsigned long fsmagic;
+ uid_t uid;
+};
+
+static struct ima_measure_rule_entry default_rules[] = {
+ {.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,
+ .flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,
+ .flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE,.fsmagic = 0xF97CFF8C,.flags = IMA_FSMAGIC},
+ {.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
+ .flags = IMA_FUNC | IMA_MASK},
+ {.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
+ .flags = IMA_FUNC | IMA_MASK},
+ {.action = MEASURE,.func = PATH_CHECK,.mask = MAY_READ,.uid = 0,
+ .flags = IMA_FUNC | IMA_MASK | IMA_UID}
+};
+
+static LIST_HEAD(measure_default_rules);
+static struct list_head *ima_measure;
+
+/**
+ * ima_match_rules - determine whether an inode matches the measure rule.
+ * @rule: a pointer to a rule
+ * @inode: a pointer to an inode
+ * @func: LIM hook identifier
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ *
+ * Returns true on rule match, false on failure.
+ */
+static bool ima_match_rules(struct ima_measure_rule_entry *rule,
+ struct inode *inode, enum ima_hooks func, int mask)
+{
+ struct task_struct *tsk = current;
+
+ if ((rule->flags & IMA_FUNC) && rule->func != func)
+ return false;
+ if ((rule->flags & IMA_MASK) && rule->mask != mask)
+ return false;
+ if ((rule->flags & IMA_FSMAGIC)
+ && rule->fsmagic != inode->i_sb->s_magic)
+ return false;
+ if ((rule->flags & IMA_UID) && rule->uid != tsk->cred->uid)
+ return false;
+ return true;
+}
+
+/**
+ * ima_match_policy - decision based on LSM and other conditions
+ * @inode: pointer to an inode for which the policy decision is being made
+ * @func: IMA hook identifier
+ * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ *
+ * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
+ * conditions.
+ *
+ * (There is no need for locking when walking the policy list,
+ * as elements in the list are never deleted, nor does the list
+ * change.)
+ */
+int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
+{
+ struct ima_measure_rule_entry *entry;
+
+ list_for_each_entry(entry, ima_measure, list) {
+ bool rc;
+
+ rc = ima_match_rules(entry, inode, func, mask);
+ if (rc)
+ return entry->action;
+ }
+ return 0;
+}
+
+/**
+ * ima_init_policy - initialize the default measure rules.
+ *
+ * (Could use the default_rules directly, but in policy patch
+ * ima_measure points to either the measure_default_rules or the
+ * the new measure_policy_rules.)
+ */
+void ima_init_policy(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(default_rules); i++)
+ list_add_tail(&default_rules[i].list, &measure_default_rules);
+ ima_measure = &measure_default_rules;
+}