[RFC,02/14] security: Add hooks to rule on setting a watch [ver #3]

Commit Message

David Howells Jan. 15, 2020, 1:30 p.m. UTC

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 <[e-mail]>
cc: Casey Schaufler <[e-mail]>
cc: Stephen Smalley <[e-mail]>
cc: [e-mail]
---

 include/linux/lsm_hooks.h |   24 ++++++++++++++++++++++++
 include/linux/security.h  |   17 +++++++++++++++++
 security/security.c       |   14 ++++++++++++++
 3 files changed, 55 insertions(+)

Patch

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 20d8cf194fb7..79d7c73676d7 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1416,6 +1416,18 @@ 
  *	@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_key:
+ *	Check to see if a process is allowed to watch for event notifications
+ *	from a key or keyring.
+ *	@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).
+ *
+ *
  * Security hooks for using the eBPF maps and programs functionalities through
  * eBPF syscalls.
  *
@@ -1698,6 +1710,12 @@  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_KEY_NOTIFICATIONS
+	int (*watch_key)(struct key *key);
+#endif
+#ifdef CONFIG_DEVICE_NOTIFICATIONS
+	int (*watch_devices)(void);
+#endif
 
 #ifdef CONFIG_SECURITY_NETWORK
 	int (*unix_stream_connect)(struct sock *sock, struct sock *other,
@@ -1985,6 +2003,12 @@  struct security_hook_heads {
 	struct hlist_head inode_notifysecctx;
 	struct hlist_head inode_setsecctx;
 	struct hlist_head inode_getsecctx;
+#ifdef CONFIG_KEY_NOTIFICATIONS
+	struct hlist_head watch_key;
+#endif
+#ifdef CONFIG_DEVICE_NOTIFICATIONS
+	struct hlist_head watch_devices;
+#endif
 #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 3e8d4bacd59d..8f2fa100d128 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1274,6 +1274,23 @@  static inline int security_locked_down(enum lockdown_reason what)
 }
 #endif	/* CONFIG_SECURITY */
 
+#if defined(CONFIG_SECURITY) && defined(CONFIG_KEY_NOTIFICATIONS)
+int security_watch_key(struct key *key);
+#else
+static inline int security_watch_key(struct key *key)
+{
+	return 0;
+}
+#endif
+#if defined(CONFIG_SECURITY) && defined(CONFIG_DEVICE_NOTIFICATIONS)
+int security_watch_devices(void);
+#else
+static inline int security_watch_devices(void)
+{
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_SECURITY_NETWORK
 
 int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk);
diff --git a/security/security.c b/security/security.c
index cd2d18d2d279..578863f230a6 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1956,6 +1956,20 @@  int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
 }
 EXPORT_SYMBOL(security_inode_getsecctx);
 
+#ifdef CONFIG_KEY_NOTIFICATIONS
+int security_watch_key(struct key *key)
+{
+	return call_int_hook(watch_key, 0, key);
+}
+#endif
+
+#ifdef CONFIG_DEVICE_NOTIFICATIONS
+int security_watch_devices(void)
+{
+	return call_int_hook(watch_devices, 0);
+}
+#endif
+
 #ifdef CONFIG_SECURITY_NETWORK
 
 int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)