[PATCH 03/13] security: Add hooks to rule on setting a watch [ver #4]

David Howells
2019-06-07T14:18:01Z

Add security hooks that will allow an LSM to rule on whether or not a watch
may be set. 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 | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/security.h | 25 +++++++++++++++++++++++++
security/security.c | 23 +++++++++++++++++++++++
3 files changed, 86 insertions(+)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 2474c3f785ca..0543449c0f6e 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1420,6 +1420,32 @@
* @ctx is a pointer in which to place the allocated security context.
* @ctxlen points to the place to put the length of @ctx.
*
+ * Security hooks for the general notification queue:
+ *
+ * @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.
+ *
+ * @watch_key:
+ * Check to see if a process is allowed to watch for event notifications
+ * from a key or keyring.
+ * @watch: The watch object
+ * @key: The key to watch.
+ *
+ * @watch_devices:
+ * Check to see if a process is allowed to watch for event notifications
+ * from devices (as a global set).
+ * @watch: The watch object
+ *
+ *
* Security hooks for using the eBPF maps and programs functionalities through
* eBPF syscalls.
*
@@ -1698,6 +1724,12 @@ union security_list_options {
int (*inode_notifysecctx)(struct inode *inode, void *ctx, u32 ctxlen);
int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen);
int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);
+#ifdef CONFIG_WATCH_QUEUE
+ int (*watch_mount)(struct watch *watch, struct path *path);
+ int (*watch_sb)(struct watch *watch, struct super_block *sb);
+ int (*watch_key)(struct watch *watch, struct key *key);
+ int (*watch_devices)(struct watch *watch);
+#endif /* CONFIG_WATCH_QUEUE */

#ifdef CONFIG_SECURITY_NETWORK
int (*unix_stream_connect)(struct sock *sock, struct sock *other,
@@ -1977,6 +2009,12 @@ struct security_hook_heads {
struct hlist_head inode_notifysecctx;
struct hlist_head inode_setsecctx;
struct hlist_head inode_getsecctx;
+#ifdef CONFIG_WATCH_QUEUE
+ struct hlist_head watch_mount;
+ struct hlist_head watch_sb;
+ struct hlist_head watch_key;
+ struct hlist_head watch_devices;
+#endif /* CONFIG_WATCH_QUEUE */
#ifdef CONFIG_SECURITY_NETWORK
struct hlist_head unix_stream_connect;
struct hlist_head unix_may_send;
diff --git a/include/linux/security.h b/include/linux/security.h
index 23c8b602c0ab..ac3bf6b5f87b 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -58,6 +58,7 @@ struct fs_context;
struct fs_parameter;
enum fs_value_type;
struct fsinfo_kparams;
+struct watch;

/* Default (no) options for the capable function */
#define CAP_OPT_NONE 0x0
@@ -396,6 +397,12 @@ void security_inode_invalidate_secctx(struct inode *inode);
int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
+#ifdef CONFIG_WATCH_QUEUE
+int security_watch_mount(struct watch *watch, struct path *path);
+int security_watch_sb(struct watch *watch, struct super_block *sb);
+int security_watch_key(struct watch *watch, struct key *key);
+int security_watch_devices(struct watch *watch);
+#endif /* CONFIG_WATCH_QUEUE */
#else /* CONFIG_SECURITY */

static inline int call_lsm_notifier(enum lsm_event event, void *data)
@@ -1215,6 +1222,24 @@ static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32
{
return -EOPNOTSUPP;
}
+#ifdef CONFIG_WATCH_QUEUE
+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_watch_key(struct watch *watch, struct key *key)
+{
+ return 0;
+}
+static inline int security_watch_devices(struct watch *watch)
+{
+ return 0;
+}
+#endif /* CONFIG_WATCH_QUEUE */
#endif /* CONFIG_SECURITY */

#ifdef CONFIG_SECURITY_NETWORK
diff --git a/security/security.c b/security/security.c
index 3af886e8fced..ee2f8539a0d5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1929,6 +1929,29 @@ int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
}
EXPORT_SYMBOL(security_inode_getsecctx);

+#ifdef CONFIG_WATCH_QUEUE
+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_watch_key(struct watch *watch, struct key *key)
+{
+ return call_int_hook(watch_key, 0, watch, key);
+}
+
+int security_watch_devices(struct watch *watch)
+{
+ return call_int_hook(watch_devices, 0, watch);
+}
+
+#endif /* CONFIG_WATCH_QUEUE */
+
#ifdef CONFIG_SECURITY_NETWORK

int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)