[PATCH 1/6] security: Add hooks to rule on setting a superblock or mount watch [ver #5]

David Howells
2019-06-28T15:50:37Z

Add security hooks that will allow an LSM to rule on whether or not a watch
may be set on a mount or on a superblock. More than one hook is required
as the watches watch different types of object.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Casey Schaufler <casey@schaufler-ca.com>
cc: Stephen Smalley <sds@tycho.nsa.gov>
cc: linux-security-module@vger.kernel.org
---

include/linux/lsm_hooks.h | 16 ++++++++++++++++
include/linux/security.h | 10 ++++++++++
security/security.c | 10 ++++++++++
3 files changed, 36 insertions(+)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 5fe387d35990..3a4d7a260572 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1433,6 +1433,18 @@
* from devices (as a global set).
* @watch: The watch object
*
+ * @watch_mount:
+ * Check to see if a process is allowed to watch for mount topology change
+ * notifications on a mount subtree.
+ * @watch: The watch object
+ * @path: The root of the subtree to watch.
+ *
+ * @watch_sb:
+ * Check to see if a process is allowed to watch for event notifications
+ * from a superblock.
+ * @watch: The watch object
+ * @sb: The superblock to watch.
+ *
* @post_notification:
* Check to see if a watch notification can be posted to a particular
* queue.
@@ -1721,6 +1733,8 @@ union security_list_options {
#ifdef CONFIG_WATCH_QUEUE
int (*watch_key)(struct watch *watch, struct key *key);
int (*watch_devices)(struct watch *watch);
+ int (*watch_mount)(struct watch *watch, struct path *path);
+ int (*watch_sb)(struct watch *watch, struct super_block *sb);
int (*post_notification)(const struct cred *w_cred,
const struct cred *cred,
struct watch_notification *n);
@@ -2007,6 +2021,8 @@ struct security_hook_heads {
#ifdef CONFIG_WATCH_QUEUE
struct hlist_head watch_key;
struct hlist_head watch_devices;
+ struct hlist_head watch_mount;
+ struct hlist_head watch_sb;
struct hlist_head post_notification;
#endif /* CONFIG_WATCH_QUEUE */
#ifdef CONFIG_SECURITY_NETWORK
diff --git a/include/linux/security.h b/include/linux/security.h
index 8a9645472232..74ec6d41eca5 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -401,6 +401,8 @@ int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
#ifdef CONFIG_WATCH_QUEUE
int security_watch_key(struct watch *watch, struct key *key);
int security_watch_devices(struct watch *watch);
+int security_watch_mount(struct watch *watch, struct path *path);
+int security_watch_sb(struct watch *watch, struct super_block *sb);
int security_post_notification(const struct cred *w_cred,
const struct cred *cred,
struct watch_notification *n);
@@ -1233,6 +1235,14 @@ static inline int security_watch_devices(struct watch *watch)
{
return 0;
}
+static inline int security_watch_mount(struct watch *watch, struct path *path)
+{
+ return 0;
+}
+static inline int security_watch_sb(struct watch *watch, struct super_block *sb)
+{
+ return 0;
+}
static inline int security_post_notification(const struct cred *w_cred,
const struct cred *cred,
struct watch_notification *n)
diff --git a/security/security.c b/security/security.c
index 1390fb1203e4..37fec6cec905 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1940,6 +1940,16 @@ int security_watch_devices(struct watch *watch)
return call_int_hook(watch_devices, 0, watch);
}

+int security_watch_mount(struct watch *watch, struct path *path)
+{
+ return call_int_hook(watch_mount, 0, watch, path);
+}
+
+int security_watch_sb(struct watch *watch, struct super_block *sb)
+{
+ return call_int_hook(watch_sb, 0, watch, sb);
+}
+
int security_post_notification(const struct cred *w_cred,
const struct cred *cred,
struct watch_notification *n)