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@@ -15,6 +15,7 @@
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#include <linux/audit.h>
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#include <linux/security.h>
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#include <linux/magic.h>
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+#include <linux/parser.h>
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#include "ima.h"
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@@ -24,7 +25,12 @@
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#define IMA_FSMAGIC 0x0004
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#define IMA_UID 0x0008
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-enum ima_action { DONT_MEASURE, MEASURE };
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+enum ima_action { UNKNOWN = -1, DONT_MEASURE = 0, MEASURE };
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+
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+#define MAX_LSM_RULES 6
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+enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
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+ LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
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+};
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struct ima_measure_rule_entry {
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struct list_head list;
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@@ -34,8 +40,15 @@ struct ima_measure_rule_entry {
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int mask;
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unsigned long fsmagic;
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uid_t uid;
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+ struct {
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+ void *rule; /* LSM file metadata specific */
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+ int type; /* audit type */
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+ } lsm[MAX_LSM_RULES];
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};
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+/* Without LSM specific knowledge, the default policy can only be
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+ * written in terms of .action, .func, .mask, .fsmagic, and .uid
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+ */
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static struct ima_measure_rule_entry default_rules[] = {
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{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,
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.flags = IMA_FSMAGIC},
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@@ -54,8 +67,11 @@ static struct ima_measure_rule_entry default_rules[] = {
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};
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static LIST_HEAD(measure_default_rules);
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+static LIST_HEAD(measure_policy_rules);
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static struct list_head *ima_measure;
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+static DEFINE_MUTEX(ima_measure_mutex);
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+
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/**
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* ima_match_rules - determine whether an inode matches the measure rule.
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* @rule: a pointer to a rule
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@@ -69,6 +85,7 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
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struct inode *inode, enum ima_hooks func, int mask)
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{
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struct task_struct *tsk = current;
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+ int i;
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if ((rule->flags & IMA_FUNC) && rule->func != func)
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return false;
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@@ -79,6 +96,39 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
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return false;
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if ((rule->flags & IMA_UID) && rule->uid != tsk->cred->uid)
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return false;
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+ for (i = 0; i < MAX_LSM_RULES; i++) {
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+ int rc;
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+ u32 osid, sid;
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+
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+ if (!rule->lsm[i].rule)
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+ continue;
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+
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+ switch (i) {
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+ case LSM_OBJ_USER:
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+ case LSM_OBJ_ROLE:
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+ case LSM_OBJ_TYPE:
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+ security_inode_getsecid(inode, &osid);
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+ rc = security_filter_rule_match(osid,
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+ rule->lsm[i].type,
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+ AUDIT_EQUAL,
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+ rule->lsm[i].rule,
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+ NULL);
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+ break;
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+ case LSM_SUBJ_USER:
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+ case LSM_SUBJ_ROLE:
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+ case LSM_SUBJ_TYPE:
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+ security_task_getsecid(tsk, &sid);
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+ rc = security_filter_rule_match(sid,
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+ rule->lsm[i].type,
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+ AUDIT_EQUAL,
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+ rule->lsm[i].rule,
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+ NULL);
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+ default:
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+ break;
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+ }
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+ if (!rc)
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+ return false;
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+ }
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return true;
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}
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@@ -112,9 +162,8 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
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/**
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* ima_init_policy - initialize the default measure rules.
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*
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- * (Could use the default_rules directly, but in policy patch
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* ima_measure points to either the measure_default_rules or the
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- * the new measure_policy_rules.)
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+ * the new measure_policy_rules.
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*/
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void ima_init_policy(void)
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{
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@@ -124,3 +173,241 @@ void ima_init_policy(void)
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list_add_tail(&default_rules[i].list, &measure_default_rules);
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ima_measure = &measure_default_rules;
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}
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+
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+/**
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+ * ima_update_policy - update default_rules with new measure rules
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+ *
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+ * Called on file .release to update the default rules with a complete new
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+ * policy. Once updated, the policy is locked, no additional rules can be
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+ * added to the policy.
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+ */
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+void ima_update_policy(void)
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+{
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+ const char *op = "policy_update";
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+ const char *cause = "already exists";
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+ int result = 1;
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+ int audit_info = 0;
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+
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+ if (ima_measure == &measure_default_rules) {
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+ ima_measure = &measure_policy_rules;
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+ cause = "complete";
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+ result = 0;
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+ }
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+ integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
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+ NULL, op, cause, result, audit_info);
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+}
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+
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+enum {
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+ Opt_err = -1,
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+ Opt_measure = 1, Opt_dont_measure,
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+ Opt_obj_user, Opt_obj_role, Opt_obj_type,
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+ Opt_subj_user, Opt_subj_role, Opt_subj_type,
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+ Opt_func, Opt_mask, Opt_fsmagic, Opt_uid
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+};
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+
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+static match_table_t policy_tokens = {
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+ {Opt_measure, "measure"},
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+ {Opt_dont_measure, "dont_measure"},
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+ {Opt_obj_user, "obj_user=%s"},
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+ {Opt_obj_role, "obj_role=%s"},
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+ {Opt_obj_type, "obj_type=%s"},
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+ {Opt_subj_user, "subj_user=%s"},
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+ {Opt_subj_role, "subj_role=%s"},
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+ {Opt_subj_type, "subj_type=%s"},
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+ {Opt_func, "func=%s"},
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+ {Opt_mask, "mask=%s"},
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+ {Opt_fsmagic, "fsmagic=%s"},
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+ {Opt_uid, "uid=%s"},
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+ {Opt_err, NULL}
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+};
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+
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+static int ima_lsm_rule_init(struct ima_measure_rule_entry *entry,
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+ char *args, int lsm_rule, int audit_type)
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+{
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+ int result;
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+
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+ entry->lsm[lsm_rule].type = audit_type;
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+ result = security_filter_rule_init(entry->lsm[lsm_rule].type,
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+ AUDIT_EQUAL, args,
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+ &entry->lsm[lsm_rule].rule);
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+ return result;
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+}
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+
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+static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
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+{
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+ struct audit_buffer *ab;
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+ char *p;
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+ int result = 0;
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+
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+ ab = audit_log_start(current->audit_context, GFP_KERNEL,
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+ AUDIT_INTEGRITY_STATUS);
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+
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+ entry->action = -1;
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+ while ((p = strsep(&rule, " \n")) != NULL) {
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+ substring_t args[MAX_OPT_ARGS];
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+ int token;
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+ unsigned long lnum;
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+
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+ if (result < 0)
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+ break;
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+ if (!*p)
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+ continue;
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+ token = match_token(p, policy_tokens, args);
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+ switch (token) {
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+ case Opt_measure:
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+ audit_log_format(ab, "%s ", "measure");
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+ entry->action = MEASURE;
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+ break;
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+ case Opt_dont_measure:
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+ audit_log_format(ab, "%s ", "dont_measure");
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+ entry->action = DONT_MEASURE;
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+ break;
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+ case Opt_func:
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+ audit_log_format(ab, "func=%s ", args[0].from);
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+ if (strcmp(args[0].from, "PATH_CHECK") == 0)
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+ entry->func = PATH_CHECK;
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+ else if (strcmp(args[0].from, "FILE_MMAP") == 0)
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+ entry->func = FILE_MMAP;
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+ else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
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+ entry->func = BPRM_CHECK;
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+ else
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+ result = -EINVAL;
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+ if (!result)
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+ entry->flags |= IMA_FUNC;
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+ break;
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+ case Opt_mask:
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+ audit_log_format(ab, "mask=%s ", args[0].from);
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+ if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
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+ entry->mask = MAY_EXEC;
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+ else if (strcmp(args[0].from, "MAY_WRITE") == 0)
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+ entry->mask = MAY_WRITE;
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+ else if (strcmp(args[0].from, "MAY_READ") == 0)
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+ entry->mask = MAY_READ;
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+ else if (strcmp(args[0].from, "MAY_APPEND") == 0)
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+ entry->mask = MAY_APPEND;
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+ else
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+ result = -EINVAL;
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+ if (!result)
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+ entry->flags |= IMA_MASK;
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+ break;
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+ case Opt_fsmagic:
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+ audit_log_format(ab, "fsmagic=%s ", args[0].from);
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+ result = strict_strtoul(args[0].from, 16,
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+ &entry->fsmagic);
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+ if (!result)
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+ entry->flags |= IMA_FSMAGIC;
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+ break;
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+ case Opt_uid:
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+ audit_log_format(ab, "uid=%s ", args[0].from);
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+ result = strict_strtoul(args[0].from, 10, &lnum);
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+ if (!result) {
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+ entry->uid = (uid_t) lnum;
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+ if (entry->uid != lnum)
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+ result = -EINVAL;
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+ else
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+ entry->flags |= IMA_UID;
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+ }
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+ break;
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+ case Opt_obj_user:
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+ audit_log_format(ab, "obj_user=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_OBJ_USER,
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+ AUDIT_OBJ_USER);
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+ break;
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+ case Opt_obj_role:
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+ audit_log_format(ab, "obj_role=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_OBJ_ROLE,
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+ AUDIT_OBJ_ROLE);
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+ break;
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+ case Opt_obj_type:
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+ audit_log_format(ab, "obj_type=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_OBJ_TYPE,
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+ AUDIT_OBJ_TYPE);
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+ break;
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+ case Opt_subj_user:
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+ audit_log_format(ab, "subj_user=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_SUBJ_USER,
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+ AUDIT_SUBJ_USER);
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+ break;
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+ case Opt_subj_role:
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+ audit_log_format(ab, "subj_role=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_SUBJ_ROLE,
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+ AUDIT_SUBJ_ROLE);
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+ break;
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+ case Opt_subj_type:
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+ audit_log_format(ab, "subj_type=%s ", args[0].from);
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+ result = ima_lsm_rule_init(entry, args[0].from,
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+ LSM_SUBJ_TYPE,
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+ AUDIT_SUBJ_TYPE);
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+ break;
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+ case Opt_err:
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+ printk(KERN_INFO "%s: unknown token: %s\n",
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+ __FUNCTION__, p);
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+ break;
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+ }
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+ }
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+ if (entry->action == UNKNOWN)
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+ result = -EINVAL;
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+
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+ audit_log_format(ab, "res=%d", result);
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+ audit_log_end(ab);
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+ return result;
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+}
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+
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+/**
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+ * ima_parse_add_rule - add a rule to measure_policy_rules
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+ * @rule - ima measurement policy rule
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+ *
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+ * Uses a mutex to protect the policy list from multiple concurrent writers.
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+ * Returns 0 on success, an error code on failure.
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+ */
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+int ima_parse_add_rule(char *rule)
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+{
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+ const char *op = "add_rule";
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+ struct ima_measure_rule_entry *entry;
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+ int result = 0;
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+ int audit_info = 0;
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+
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+ /* Prevent installed policy from changing */
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+ if (ima_measure != &measure_default_rules) {
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+ integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
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+ NULL, op, "already exists",
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+ -EACCES, audit_info);
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+ return -EACCES;
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+ }
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+
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+ entry = kzalloc(sizeof(*entry), GFP_KERNEL);
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+ if (!entry) {
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+ integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
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+ NULL, op, "-ENOMEM", -ENOMEM, audit_info);
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+ return -ENOMEM;
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+ }
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+
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+ INIT_LIST_HEAD(&entry->list);
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+
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+ result = ima_parse_rule(rule, entry);
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+ if (!result) {
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+ mutex_lock(&ima_measure_mutex);
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+ list_add_tail(&entry->list, &measure_policy_rules);
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+ mutex_unlock(&ima_measure_mutex);
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+ } else
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+ kfree(entry);
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+ return result;
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+}
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+
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+/* ima_delete_rules called to cleanup invalid policy */
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+void ima_delete_rules()
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+{
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+ struct ima_measure_rule_entry *entry, *tmp;
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+
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+ mutex_lock(&ima_measure_mutex);
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+ list_for_each_entry_safe(entry, tmp, &measure_policy_rules, list) {
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+ list_del(&entry->list);
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+ kfree(entry);
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+ }
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+ mutex_unlock(&ima_measure_mutex);
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+}
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