[PATCH v15 09/26] ima: Move ima_lsm_policy_notifier into ima_namespace

Stefan Berger
2023-02-06T14:04:31Z

Move the ima_lsm_policy_notifier into the ima_namespace. Each IMA
namespace can now register its own LSM policy change notifier callback.
The policy change notifier for the init_ima_ns still remains in init_ima()
and therefore handle the registration of the callback for all other
namespaces in init_ima_namespace().

Rate-limit the kernel warning 'rule for LSM is undefined` for
IMA namespace to avoid flooding the kernel log with this type of message.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>

---

v15:
- Pass ima_namespace into ima_match_rules() to pass to ima_lsm_copy_rule()

v11:
- Renamed 'rc' to 'ret'
- Use pr_warn_ratelimited('rule for LSM...') for IMA namespaces

v10:
- Only call pr_warn('rule for LSM is undefined`) for init_ima_ns
---
security/integrity/ima/ima.h | 2 ++
security/integrity/ima/ima_init_ima_ns.c | 14 ++++++++++
security/integrity/ima/ima_main.c | 6 +----
security/integrity/ima/ima_policy.c | 34 ++++++++++++++++--------
4 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 75993ad061fa..db28d6d222a6 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -144,6 +144,8 @@ struct ima_namespace {
int valid_policy;

struct dentry *ima_policy;
+
+ struct notifier_block ima_lsm_policy_notifier;
} __randomize_layout;
extern struct ima_namespace init_ima_ns;

diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
index 425eed1c6838..c4fe8f3e9a73 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -10,6 +10,8 @@

static int ima_init_namespace(struct ima_namespace *ns)
{
+ int ret;
+
INIT_LIST_HEAD(&ns->ima_default_rules);
INIT_LIST_HEAD(&ns->ima_policy_rules);
INIT_LIST_HEAD(&ns->ima_temp_rules);
@@ -30,6 +32,15 @@ static int ima_init_namespace(struct ima_namespace *ns)
ns->valid_policy = 1;
ns->ima_fs_flags = 0;

+ if (ns != &init_ima_ns) {
+ ns->ima_lsm_policy_notifier.notifier_call =
+ ima_lsm_policy_change;
+ ret = register_blocking_lsm_notifier
+ (&ns->ima_lsm_policy_notifier);
+ if (ret)
+ return ret;
+ }
+
return 0;
}

@@ -39,5 +50,8 @@ int __init ima_ns_init(void)
}

struct ima_namespace init_ima_ns = {
+ .ima_lsm_policy_notifier = {
+ .notifier_call = ima_lsm_policy_change,
+ },
};
EXPORT_SYMBOL(init_ima_ns);
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index e3a3a54dc79e..c7a5f47b50fc 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -38,10 +38,6 @@ int ima_appraise;
int __ro_after_init 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();
@@ -1096,7 +1092,7 @@ static int __init init_ima(void)
if (error)
return error;

- error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
+ error = register_blocking_lsm_notifier(&ns->ima_lsm_policy_notifier);
if (error)
pr_warn("Couldn't register LSM notifier, error %d\n", error);

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 502b1e8021a6..8e71b28855a4 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -392,7 +392,8 @@ static void ima_free_rule(struct ima_rule_entry *entry)
kfree(entry);
}

-static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
+static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_namespace *ns,
+ struct ima_rule_entry *entry)
{
struct ima_rule_entry *nentry;
int i;
@@ -417,19 +418,26 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
nentry->lsm[i].args_p,
&nentry->lsm[i].rule);
- if (!nentry->lsm[i].rule)
- pr_warn("rule for LSM \'%s\' is undefined\n",
- nentry->lsm[i].args_p);
+ if (!nentry->lsm[i].rule) {
+ if (ns == &init_ima_ns)
+ pr_warn("rule for LSM \'%s\' is undefined\n",
+ nentry->lsm[i].args_p);
+ else
+ pr_warn_ratelimited
+ ("rule for LSM \'%s\' is undefined\n",
+ nentry->lsm[i].args_p);
+ }
}
return nentry;
}

-static int ima_lsm_update_rule(struct ima_rule_entry *entry)
+static int ima_lsm_update_rule(struct ima_namespace *ns,
+ struct ima_rule_entry *entry)
{
int i;
struct ima_rule_entry *nentry;

- nentry = ima_lsm_copy_rule(entry);
+ nentry = ima_lsm_copy_rule(ns, entry);
if (!nentry)
return -ENOMEM;

@@ -473,7 +481,7 @@ static void ima_lsm_update_rules(struct ima_namespace *ns)
if (!ima_rule_contains_lsm_cond(entry))
continue;

- result = ima_lsm_update_rule(entry);
+ result = ima_lsm_update_rule(ns, entry);
if (result) {
pr_err("lsm rule update error %d\n", result);
return;
@@ -484,12 +492,14 @@ static void ima_lsm_update_rules(struct ima_namespace *ns)
int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
void *lsm_data)
{
- struct ima_namespace *ns = &init_ima_ns;
+ struct ima_namespace *ns;

if (event != LSM_POLICY_CHANGE)
return NOTIFY_DONE;

+ ns = container_of(nb, struct ima_namespace, ima_lsm_policy_notifier);
ima_lsm_update_rules(ns);
+
return NOTIFY_OK;
}

@@ -544,6 +554,7 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,

/**
* ima_match_rules - determine whether an inode matches the policy rule.
+ * @ns: IMA namespace that has the policy
* @rule: a pointer to a rule
* @mnt_userns: user namespace of the mount the inode was found from
* @inode: a pointer to an inode
@@ -555,7 +566,8 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
*
* Returns true on rule match, false on failure.
*/
-static bool ima_match_rules(struct ima_rule_entry *rule,
+static bool ima_match_rules(struct ima_namespace *ns,
+ struct ima_rule_entry *rule,
struct user_namespace *mnt_userns,
struct inode *inode, const struct cred *cred,
u32 secid, enum ima_hooks func, int mask,
@@ -657,7 +669,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
}

if (rc == -ESTALE && !rule_reinitialized) {
- lsm_rule = ima_lsm_copy_rule(rule);
+ lsm_rule = ima_lsm_copy_rule(ns, rule);
if (lsm_rule) {
rule_reinitialized = true;
goto retry;
@@ -747,7 +759,7 @@ int ima_match_policy(struct ima_namespace *ns,
if (!(entry->action & actmask))
continue;

- if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
+ if (!ima_match_rules(ns, entry, mnt_userns, inode, cred, secid,
func, mask, func_data))
continue;

--
2.37.3