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Groups > linux.kernel > #1639892

[RFC 06/11] ima, fs: release namespace policy resources

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Release all namespace IMA policy resources when the mount namespace is
released.
This is the suggested mechanism to release namespace policy resources,
but we still can discuss other methods to avoid cross-component changes.

Signed-off-by: Guilherme Magalhaes <guilherme.magalhaes@hpe.com>
---
 fs/namespace.c                  |  4 ++++
 include/linux/integrity.h       |  9 +++++++++
 security/integrity/ima/ima_fs.c | 26 ++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/fs/namespace.c b/fs/namespace.c
index cc1375ef..80940998 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -15,6 +15,7 @@
 #include <linux/user_namespace.h>
 #include <linux/namei.h>
 #include <linux/security.h>
+#include <linux/integrity.h>
 #include <linux/cred.h>
 #include <linux/idr.h>
 #include <linux/init.h>		/* init_rootfs */
@@ -3283,6 +3284,9 @@ void put_mnt_ns(struct mnt_namespace *ns)
 {
 	if (!atomic_dec_and_test(&ns->count))
 		return;
+
+	ima_mnt_namespace_dying(ns->ns.inum);
+
 	drop_collected_mounts(&ns->root->mnt);
 	free_mnt_ns(ns);
 }
diff --git a/include/linux/integrity.h b/include/linux/integrity.h
index c2d6082..034d082 100644
--- a/include/linux/integrity.h
+++ b/include/linux/integrity.h
@@ -43,4 +43,13 @@ static inline void integrity_load_keys(void)
 }
 #endif /* CONFIG_INTEGRITY */
 
+#ifdef CONFIG_IMA_PER_NAMESPACE
+extern void ima_mnt_namespace_dying(unsigned int ns_id);
+#else
+static inline void ima_mnt_namespace_dying(unsigned int ns_id)
+{
+	return;
+}
+#endif /* CONFIG_IMA_PER_NAMESPACE */
+
 #endif /* _LINUX_INTEGRITY_H */
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index ce6dcdf..56ba0ff 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -423,6 +423,7 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
 				    "policy_update", "signed policy required",
 				    1, 0);
+
 		if (ima_appraise & IMA_APPRAISE_ENFORCE)
 			result = -EACCES;
 	} else {
@@ -579,6 +580,31 @@ static int create_mnt_ns_directory(unsigned int ns_id)
 	return result;
 }
 
+/*
+ * ima_mnt_namespace_dying - releases all namespace policy resources
+ * It is called automatically when the namespace is released.
+ * @ns_id namespace id to be released
+ *
+ * Note: This function is called by put_mnt_ns() in the context
+ * of a namespace release. We need to make sure that a lock on
+ * this path is allowed.
+ */
+void ima_mnt_namespace_dying(unsigned int ns_id)
+{
+	struct ima_ns_policy *p;
+
+	spin_lock(&ima_ns_policy_lock);
+	p = radix_tree_delete(&ima_ns_policy_mapping, ns_id);
+
+	if (!p) {
+		spin_unlock(&ima_ns_policy_lock);
+		return;
+	}
+
+	free_namespace_policy(p);
+	spin_unlock(&ima_ns_policy_lock);
+}
+
 static ssize_t handle_new_namespace_policy(const char *data, size_t datalen)
 {
 	unsigned int ns_id;
-- 
2.7.4

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[RFC 00/11] ima: namespace support for IMA policy Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:30 +0200
  [RFC 01/11] ima: qualify pathname in audit info record Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:30 +0200
  [RFC 04/11] ima: add support to namespace securityfs file Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:30 +0200
    Re: [RFC 04/11] ima: add support to namespace securityfs file Tycho Andersen <tycho@docker.com> - 2017-05-18 23:40 +0200
    Re: [RFC 04/11] ima: add support to namespace securityfs file Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-05-24 22:20 +0200
  [RFC 02/11] ima: qualify pathname in audit measurement record Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:30 +0200
  [RFC 10/11] ima: handling all policy flags per namespace using ima_ns_policy structure Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:30 +0200
  [RFC 07/11] ima: new namespace policy structure to track initial namespace policy data Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:40 +0200
  [RFC 08/11] ima: block initial namespace id on the namespace policy interface Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:40 +0200
  [RFC 05/11] ima: store new namespace policy structure in a radix tree Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:40 +0200
  [RFC 06/11] ima, fs: release namespace policy resources Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:40 +0200
  [RFC 09/11] ima: delete namespace policy securityfs file in write-once mode Guilherme Magalhaes <guilherme.magalhaes@hpe.com> - 2017-05-11 18:40 +0200

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