From 344fa64ef8f6740e99b32ab788b6e3742d7284b3 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Wed, 12 Feb 2020 13:58:35 +0000
Subject: [PATCH] security: Add a hook for the point of notification insertion
Add a security hook that allows an LSM to rule on whether a notification
message is allowed to be inserted into a particular watch queue.
The hook is given the following information:
(1) The credentials of the triggerer (which may be init_cred for a system
notification, eg. a hardware error).
(2) The credentials of the whoever set the watch.
(3) The notification message.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jamorris@linux.microsoft.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_hook_defs.h | 5 +++++
include/linux/lsm_hooks.h | 9 +++++++++
include/linux/security.h | 15 +++++++++++++++
security/security.c | 9 +++++++++
4 files changed, 38 insertions(+)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 5616b2567aa7f..e0def45b5cc56 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -253,6 +253,11 @@ LSM_HOOK(int, 0, inode_setsecctx, struct dentry *dentry, void *ctx, u32 ctxlen)
LSM_HOOK(int, 0, inode_getsecctx, struct inode *inode, void **ctx,
u32 *ctxlen)
+#if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE)
+LSM_HOOK(int, 0, post_notification, const struct cred *w_cred,
+ const struct cred *cred, struct watch_notification *n)
+#endif /* CONFIG_SECURITY && CONFIG_KEY_NOTIFICATIONS */
+
#ifdef CONFIG_SECURITY_NETWORK
LSM_HOOK(int, 0, unix_stream_connect, struct sock *sock, struct sock *other,
struct sock *newsk)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 988ca0df7824c..0b5e5769b8367 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1437,6 +1437,15 @@
* @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:
+ *
+ * @post_notification:
+ * Check to see if a watch notification can be posted to a particular
+ * queue.
+ * @w_cred: The credentials of the whoever set the watch.
+ * @cred: The event-triggerer's credentials
+ * @n: The notification being posted
+ *
* Security hooks for using the eBPF maps and programs functionalities through
* eBPF syscalls.
*
diff --git a/include/linux/security.h b/include/linux/security.h
index a8d9310472dfa..9a5d12ab491bc 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -56,6 +56,8 @@ struct mm_struct;
struct fs_context;
struct fs_parameter;
enum fs_value_type;
+struct watch;
+struct watch_notification;
/* Default (no) options for the capable function */
#define CAP_OPT_NONE 0x0
@@ -1275,6 +1277,19 @@ static inline int security_locked_down(enum lockdown_reason what)
}
#endif /* CONFIG_SECURITY */
+#if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE)
+int security_post_notification(const struct cred *w_cred,
+ const struct cred *cred,
+ struct watch_notification *n);
+#else
+static inline int security_post_notification(const struct cred *w_cred,
+ const struct cred *cred,
+ struct watch_notification *n)
+{
+ 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 7fed24b9d57e6..7d55607120b48 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2007,6 +2007,15 @@ int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
}
EXPORT_SYMBOL(security_inode_getsecctx);
+#ifdef CONFIG_WATCH_QUEUE
+int security_post_notification(const struct cred *w_cred,
+ const struct cred *cred,
+ struct watch_notification *n)
+{
+ return call_int_hook(post_notification, 0, w_cred, cred, n);
+}
+#endif /* CONFIG_WATCH_QUEUE */
+
#ifdef CONFIG_SECURITY_NETWORK
int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)
--
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