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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 03/17] security: Add a hook for the point of notification insertion [ver #4] From: David Howells To: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Cc: Casey Schaufler , Stephen Smalley , linux-security-module@vger.kernel.org, dhowells@redhat.com, dhowells@redhat.com, casey@schaufler-ca.com, sds@tycho.nsa.gov, nicolas.dichtel@6wind.com, raven@themaw.net, christian@brauner.io, andres@anarazel.de, jlayton@redhat.com, dray@redhat.com, kzak@redhat.com, keyrings@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 09 Mar 2020 12:17:41 +0000 Message-ID: <158375626100.334846.3654197678658672620.stgit@warthog.procyon.org.uk> In-Reply-To: <158375623086.334846.16121725232323108842.stgit@warthog.procyon.org.uk> References: <158375623086.334846.16121725232323108842.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.21 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: keyrings-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org 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 cc: Casey Schaufler cc: Stephen Smalley cc: linux-security-module@vger.kernel.org --- include/linux/lsm_hooks.h | 14 ++++++++++++++ include/linux/security.h | 14 ++++++++++++++ security/security.c | 9 +++++++++ 3 files changed, 37 insertions(+) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 79d7c73676d7..16530255dc11 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1427,6 +1427,12 @@ * Check to see if a process is allowed to watch for event notifications * from devices (as a global set). * + * @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. @@ -1716,6 +1722,11 @@ union security_list_options { #ifdef CONFIG_DEVICE_NOTIFICATIONS int (*watch_devices)(void); #endif +#ifdef CONFIG_WATCH_QUEUE + int (*post_notification)(const struct cred *w_cred, + const struct cred *cred, + struct watch_notification *n); +#endif #ifdef CONFIG_SECURITY_NETWORK int (*unix_stream_connect)(struct sock *sock, struct sock *other, @@ -2009,6 +2020,9 @@ struct security_hook_heads { #ifdef CONFIG_DEVICE_NOTIFICATIONS struct hlist_head watch_devices; #endif +#ifdef CONFIG_WATCH_QUEUE + struct hlist_head post_notification; +#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 7a36064a64ea..910a1efa9a79 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -57,6 +57,8 @@ 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 @@ -1292,6 +1294,18 @@ static inline int security_watch_devices(void) return 0; } #endif +#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 diff --git a/security/security.c b/security/security.c index 22877f47cf62..db7b574c9c70 100644 --- a/security/security.c +++ b/security/security.c @@ -1988,6 +1988,15 @@ 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_KEY_NOTIFICATIONS int security_watch_key(struct key *key) {