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authorJanne Karhunen <janne.karhunen@gmail.com>2019-06-14 15:20:15 +0300
committerMimi Zohar <zohar@linux.ibm.com>2019-06-14 09:02:43 -0400
commitb169424551930a9325f700f502802f4d515194e5 (patch)
tree5b38bb996cfe6791c0c672a1576c198ed8c9599e /security
parent42df744c4166af6959eda2df1ee5cde744d4a1c3 (diff)
ima: use the lsm policy update notifier
Don't do lazy policy updates while running the rule matching, run the updates as they happen. Depends on commit f242064c5df3 ("LSM: switch to blocking policy update notifiers") Signed-off-by: Janne Karhunen <janne.karhunen@gmail.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima.h2
-rw-r--r--security/integrity/ima/ima_main.c8
-rw-r--r--security/integrity/ima/ima_policy.c116
3 files changed, 106 insertions, 20 deletions
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d213e835c498..2203451862d4 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -154,6 +154,8 @@ unsigned long ima_get_binary_runtime_size(void);
int ima_init_template(void);
void ima_init_template_list(void);
int __init ima_init_digests(void);
+int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
+ void *lsm_data);
/*
* used to protect h_table and sha_table
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index f16353b5097e..9e3ea8a3f2db 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -43,6 +43,10 @@ int ima_appraise;
int ima_hash_algo = HASH_ALGO_SHA1;
static int hash_setup_done;
+static struct notifier_block ima_lsm_policy_notifier = {
+ .notifier_call = ima_lsm_policy_change,
+};
+
static int __init hash_setup(char *str)
{
struct ima_template_desc *template_desc = ima_template_desc_current();
@@ -621,6 +625,10 @@ static int __init init_ima(void)
error = ima_init();
}
+ error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
+ if (error)
+ pr_warn("Couldn't register LSM notifier, error %d\n", error);
+
if (!error)
ima_update_policy_flag();
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index cd1b7281244e..ec4efa8ea366 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -249,31 +249,113 @@ static int __init default_appraise_policy_setup(char *str)
}
__setup("ima_appraise_tcb", default_appraise_policy_setup);
+static void ima_lsm_free_rule(struct ima_rule_entry *entry)
+{
+ int i;
+
+ for (i = 0; i < MAX_LSM_RULES; i++) {
+ kfree(entry->lsm[i].rule);
+ kfree(entry->lsm[i].args_p);
+ }
+ kfree(entry);
+}
+
+static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
+{
+ struct ima_rule_entry *nentry;
+ int i, result;
+
+ nentry = kmalloc(sizeof(*nentry), GFP_KERNEL);
+ if (!nentry)
+ return NULL;
+
+ /*
+ * Immutable elements are copied over as pointers and data; only
+ * lsm rules can change
+ */
+ memcpy(nentry, entry, sizeof(*nentry));
+ memset(nentry->lsm, 0, FIELD_SIZEOF(struct ima_rule_entry, lsm));
+
+ for (i = 0; i < MAX_LSM_RULES; i++) {
+ if (!entry->lsm[i].rule)
+ continue;
+
+ nentry->lsm[i].type = entry->lsm[i].type;
+ nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p,
+ GFP_KERNEL);
+ if (!nentry->lsm[i].args_p)
+ goto out_err;
+
+ result = security_filter_rule_init(nentry->lsm[i].type,
+ Audit_equal,
+ nentry->lsm[i].args_p,
+ &nentry->lsm[i].rule);
+ if (result == -EINVAL)
+ pr_warn("ima: rule for LSM \'%d\' is undefined\n",
+ entry->lsm[i].type);
+ }
+ return nentry;
+
+out_err:
+ ima_lsm_free_rule(nentry);
+ return NULL;
+}
+
+static int ima_lsm_update_rule(struct ima_rule_entry *entry)
+{
+ struct ima_rule_entry *nentry;
+
+ nentry = ima_lsm_copy_rule(entry);
+ if (!nentry)
+ return -ENOMEM;
+
+ list_replace_rcu(&entry->list, &nentry->list);
+ synchronize_rcu();
+ ima_lsm_free_rule(entry);
+
+ return 0;
+}
+
/*
* The LSM policy can be reloaded, leaving the IMA LSM based rules referring
* to the old, stale LSM policy. Update the IMA LSM based rules to reflect
- * the reloaded LSM policy. We assume the rules still exist; and BUG_ON() if
- * they don't.
+ * the reloaded LSM policy.
*/
static void ima_lsm_update_rules(void)
{
- struct ima_rule_entry *entry;
- int result;
- int i;
+ struct ima_rule_entry *entry, *e;
+ int i, result, needs_update;
- list_for_each_entry(entry, &ima_policy_rules, list) {
+ list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
+ needs_update = 0;
for (i = 0; i < MAX_LSM_RULES; i++) {
- if (!entry->lsm[i].rule)
- continue;
- result = security_filter_rule_init(entry->lsm[i].type,
- Audit_equal,
- entry->lsm[i].args_p,
- &entry->lsm[i].rule);
- BUG_ON(!entry->lsm[i].rule);
+ if (entry->lsm[i].rule) {
+ needs_update = 1;
+ break;
+ }
+ }
+ if (!needs_update)
+ continue;
+
+ result = ima_lsm_update_rule(entry);
+ if (result) {
+ pr_err("ima: lsm rule update error %d\n",
+ result);
+ return;
}
}
}
+int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
+ void *lsm_data)
+{
+ if (event != LSM_POLICY_CHANGE)
+ return NOTIFY_DONE;
+
+ ima_lsm_update_rules();
+ return NOTIFY_OK;
+}
+
/**
* ima_match_rules - determine whether an inode matches the measure rule.
* @rule: a pointer to a rule
@@ -327,11 +409,10 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
for (i = 0; i < MAX_LSM_RULES; i++) {
int rc = 0;
u32 osid;
- int retried = 0;
if (!rule->lsm[i].rule)
continue;
-retry:
+
switch (i) {
case LSM_OBJ_USER:
case LSM_OBJ_ROLE:
@@ -352,11 +433,6 @@ retry:
default:
break;
}
- if ((rc < 0) && (!retried)) {
- retried = 1;
- ima_lsm_update_rules();
- goto retry;
- }
if (!rc)
return false;
}