[PATCH 0/2] New LSM hooks for the TUN driver

[PATCH 0/2] New LSM hooks for the TUN driver

[Paul Moore]

This is the third, and hopefully final, version of the new LSM TUN hooks.  This
version incorporates all outstanding feedback as well as my sign-off and ACKs
from both Eric and Serge (see patches).  However, the patches are still missing
an ACK from netdev - I haven't heard any objections but I'm not certain anyone
from netdev has really taken a look yet.

Dave and James - these patches once again straddle that line between networking
and security; while James has usually ushered these types of patches upstream
in the past I'll let you two fight it out again for the honors (assuming you
are both okay with the patches).

The patches can also be found in git form here:

 * git://git.infradead.org/users/pcmoore/lblnet-2.6_next

Thanks.

---

Paul Moore (2):
      selinux: Support for the new TUN LSM hooks
      lsm: Add hooks to the TUN driver


 drivers/net/tun.c                          |   22 +++++++---
 include/linux/security.h                   |   31 ++++++++++++++
 security/capability.c                      |   19 +++++++++
 security/security.c                        |   18 ++++++++
 security/selinux/hooks.c                   |   60 +++++++++++++++++++++++++++-
 security/selinux/include/av_inherit.h      |    1 
 security/selinux/include/av_permissions.h  |   22 ++++++++++
 security/selinux/include/class_to_string.h |    1 
 security/selinux/include/flask.h           |    1 
 9 files changed, 166 insertions(+), 9 deletions(-)

[PATCH 1/2] lsm: Add hooks to the TUN driver

[Paul Moore]

The TUN driver lacks any LSM hooks which makes it difficult for LSM modules,
such as SELinux, to enforce access controls on network traffic generated by
TUN users; this is particularly problematic for virtualization apps such as
QEMU and KVM.  This patch adds three new LSM hooks designed to control the
creation and attachment of TUN devices, the hooks are:

 * security_tun_dev_create()
   Provides access control for the creation of new TUN devices

 * security_tun_dev_post_create()
   Provides the ability to create the necessary socket LSM state for newly
   created TUN devices

 * security_tun_dev_attach()
   Provides access control for attaching to existing, persistent TUN devices
   and the ability to update the TUN device's socket LSM state as necessary

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Eric Paris <eparis@parisplace.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
---

 drivers/net/tun.c        |   22 +++++++++++++++-------
 include/linux/security.h |   31 +++++++++++++++++++++++++++++++
 security/capability.c    |   19 +++++++++++++++++++
 security/security.c      |   18 ++++++++++++++++++
 4 files changed, 83 insertions(+), 7 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 42b6c63..87214a2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -130,17 +130,10 @@ static inline struct tun_sock *tun_sk(struct sock *sk)
 static int tun_attach(struct tun_struct *tun, struct file *file)
 {
 	struct tun_file *tfile = file->private_data;
-	const struct cred *cred = current_cred();
 	int err;
 
 	ASSERT_RTNL();
 
-	/* Check permissions */
-	if (((tun->owner != -1 && cred->euid != tun->owner) ||
-	     (tun->group != -1 && !in_egroup_p(tun->group))) &&
-		!capable(CAP_NET_ADMIN))
-		return -EPERM;
-
 	netif_tx_lock_bh(tun->dev);
 
 	err = -EINVAL;
@@ -926,6 +919,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 
 	dev = __dev_get_by_name(net, ifr->ifr_name);
 	if (dev) {
+		const struct cred *cred = current_cred();
+
 		if (ifr->ifr_flags & IFF_TUN_EXCL)
 			return -EBUSY;
 		if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
@@ -935,6 +930,14 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		else
 			return -EINVAL;
 
+		if (((tun->owner != -1 && cred->euid != tun->owner) ||
+		     (tun->group != -1 && !in_egroup_p(tun->group))) &&
+		    !capable(CAP_NET_ADMIN))
+			return -EPERM;
+		err = security_tun_dev_attach(tun->sk);
+		if (err < 0)
+			return err;
+
 		err = tun_attach(tun, file);
 		if (err < 0)
 			return err;
@@ -947,6 +950,9 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 
 		if (!capable(CAP_NET_ADMIN))
 			return -EPERM;
+		err = security_tun_dev_create();
+		if (err < 0)
+			return err;
 
 		/* Set dev type */
 		if (ifr->ifr_flags & IFF_TUN) {
@@ -989,6 +995,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		tun->sk = sk;
 		container_of(sk, struct tun_sock, sk)->tun = tun;
 
+		security_tun_dev_post_create(sk);
+
 		tun_net_init(dev);
 
 		if (strchr(dev->name, '%')) {
diff --git a/include/linux/security.h b/include/linux/security.h
index 1f16eea..d0e7d4a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -994,6 +994,17 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	Sets the connection's peersid to the secmark on skb.
  * @req_classify_flow:
  *	Sets the flow's sid to the openreq sid.
+ * @tun_dev_create:
+ *	Check permissions prior to creating a new TUN device.
+ * @tun_dev_post_create:
+ *	This hook allows a module to update or allocate a per-socket security
+ *	structure.
+ *	@sk contains the newly created sock structure.
+ * @tun_dev_attach:
+ *	Check permissions prior to attaching to a persistent TUN device.  This
+ *	hook can also be used by the module to update any security state
+ *	associated with the TUN device's sock structure.
+ *	@sk contains the existing sock structure.
  *
  * Security hooks for XFRM operations.
  *
@@ -1592,6 +1603,9 @@ struct security_operations {
 	void (*inet_csk_clone) (struct sock *newsk, const struct request_sock *req);
 	void (*inet_conn_established) (struct sock *sk, struct sk_buff *skb);
 	void (*req_classify_flow) (const struct request_sock *req, struct flowi *fl);
+	int (*tun_dev_create)(void);
+	void (*tun_dev_post_create)(struct sock *sk);
+	int (*tun_dev_attach)(struct sock *sk);
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
@@ -2575,6 +2589,9 @@ void security_inet_csk_clone(struct sock *newsk,
 			const struct request_sock *req);
 void security_inet_conn_established(struct sock *sk,
 			struct sk_buff *skb);
+int security_tun_dev_create(void);
+void security_tun_dev_post_create(struct sock *sk);
+int security_tun_dev_attach(struct sock *sk);
 
 #else	/* CONFIG_SECURITY_NETWORK */
 static inline int security_unix_stream_connect(struct socket *sock,
@@ -2725,6 +2742,20 @@ static inline void security_inet_conn_established(struct sock *sk,
 			struct sk_buff *skb)
 {
 }
+
+static inline int security_tun_dev_create(void)
+{
+	return 0;
+}
+
+static inline void security_tun_dev_post_create(struct sock *sk)
+{
+}
+
+static inline int security_tun_dev_attach(struct sock *sk)
+{
+	return 0;
+}
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
diff --git a/security/capability.c b/security/capability.c
index 88f752e..8cb75b6 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -701,10 +701,26 @@ static void cap_inet_conn_established(struct sock *sk, struct sk_buff *skb)
 {
 }
 
+
+
 static void cap_req_classify_flow(const struct request_sock *req,
 				  struct flowi *fl)
 {
 }
+
+static int cap_tun_dev_create(void)
+{
+	return 0;
+}
+
+static void cap_tun_dev_post_create(struct sock *sk)
+{
+}
+
+static int cap_tun_dev_attach(struct sock *sk)
+{
+	return 0;
+}
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
@@ -1020,6 +1036,9 @@ void security_fixup_ops(struct security_operations *ops)
 	set_to_cap_if_null(ops, inet_csk_clone);
 	set_to_cap_if_null(ops, inet_conn_established);
 	set_to_cap_if_null(ops, req_classify_flow);
+	set_to_cap_if_null(ops, tun_dev_create);
+	set_to_cap_if_null(ops, tun_dev_post_create);
+	set_to_cap_if_null(ops, tun_dev_attach);
 #endif	/* CONFIG_SECURITY_NETWORK */
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
 	set_to_cap_if_null(ops, xfrm_policy_alloc_security);
diff --git a/security/security.c b/security/security.c
index dc7674f..dc6953c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1112,6 +1112,24 @@ void security_inet_conn_established(struct sock *sk,
 	security_ops->inet_conn_established(sk, skb);
 }
 
+int security_tun_dev_create(void)
+{
+	return security_ops->tun_dev_create();
+}
+EXPORT_SYMBOL(security_tun_dev_create);
+
+void security_tun_dev_post_create(struct sock *sk)
+{
+	return security_ops->tun_dev_post_create(sk);
+}
+EXPORT_SYMBOL(security_tun_dev_post_create);
+
+int security_tun_dev_attach(struct sock *sk)
+{
+	return security_ops->tun_dev_attach(sk);
+}
+EXPORT_SYMBOL(security_tun_dev_attach);
+
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM

[PATCH 2/2] selinux: Support for the new TUN LSM hooks

[Paul Moore]

Add support for the new TUN LSM hooks: security_tun_dev_create(),
security_tun_dev_post_create() and security_tun_dev_attach().  This includes
the addition of a new object class, tun_socket, which represents the socks
associated with TUN devices.  The _tun_dev_create() and _tun_dev_post_create()
hooks are fairly similar to the standard socket functions but _tun_dev_attach()
is a bit special.  The _tun_dev_attach() is unique because it involves a
domain attaching to an existing TUN device and its associated tun_socket
object, an operation which does not exist with standard sockets and most
closely resembles a relabel operation.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Eric Paris <eparis@parisplace.org>
---

 security/selinux/hooks.c                   |   60 +++++++++++++++++++++++++++-
 security/selinux/include/av_inherit.h      |    1 
 security/selinux/include/av_permissions.h  |   22 ++++++++++
 security/selinux/include/class_to_string.h |    1 
 security/selinux/include/flask.h           |    1 
 5 files changed, 83 insertions(+), 2 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 8d8b69c..8ee6b07 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -13,8 +13,8 @@
  *					   Eric Paris <eparis@redhat.com>
  *  Copyright (C) 2004-2005 Trusted Computer Solutions, Inc.
  *			    <dgoeddel@trustedcs.com>
- *  Copyright (C) 2006, 2007 Hewlett-Packard Development Company, L.P.
- *		Paul Moore <paul.moore@hp.com>
+ *  Copyright (C) 2006, 2007, 2009 Hewlett-Packard Development Company, L.P.
+ *	Paul Moore <paul.moore@hp.com>
  *  Copyright (C) 2007 Hitachi Software Engineering Co., Ltd.
  *		       Yuichi Nakamura <ynakam@hitachisoft.jp>
  *
@@ -4309,6 +4309,59 @@ static void selinux_req_classify_flow(const struct request_sock *req,
 	fl->secid = req->secid;
 }
 
+static int selinux_tun_dev_create(void)
+{
+	u32 sid = current_sid();
+
+	/* we aren't taking into account the "sockcreate" SID since the socket
+	 * that is being created here is not a socket in the traditional sense,
+	 * instead it is a private sock, accessible only to the kernel, and
+	 * representing a wide range of network traffic spanning multiple
+	 * connections unlike traditional sockets - check the TUN driver to
+	 * get a better understanding of why this socket is special */
+
+	return avc_has_perm(sid, sid, SECCLASS_TUN_SOCKET, TUN_SOCKET__CREATE,
+			    NULL);
+}
+
+static void selinux_tun_dev_post_create(struct sock *sk)
+{
+	struct sk_security_struct *sksec = sk->sk_security;
+
+	/* we don't currently perform any NetLabel based labeling here and it
+	 * isn't clear that we would want to do so anyway; while we could apply
+	 * labeling without the support of the TUN user the resulting labeled
+	 * traffic from the other end of the connection would almost certainly
+	 * cause confusion to the TUN user that had no idea network labeling
+	 * protocols were being used */
+
+	/* see the comments in selinux_tun_dev_create() about why we don't use
+	 * the sockcreate SID here */
+
+	sksec->sid = current_sid();
+	sksec->sclass = SECCLASS_TUN_SOCKET;
+}
+
+static int selinux_tun_dev_attach(struct sock *sk)
+{
+	struct sk_security_struct *sksec = sk->sk_security;
+	u32 sid = current_sid();
+	int err;
+
+	err = avc_has_perm(sid, sksec->sid, SECCLASS_TUN_SOCKET,
+			   TUN_SOCKET__RELABELFROM, NULL);
+	if (err)
+		return err;
+	err = avc_has_perm(sid, sid, SECCLASS_TUN_SOCKET,
+			   TUN_SOCKET__RELABELTO, NULL);
+	if (err)
+		return err;
+
+	sksec->sid = sid;
+
+	return 0;
+}
+
 static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
 {
 	int err = 0;
@@ -5477,6 +5530,9 @@ static struct security_operations selinux_ops = {
 	.inet_csk_clone =		selinux_inet_csk_clone,
 	.inet_conn_established =	selinux_inet_conn_established,
 	.req_classify_flow =		selinux_req_classify_flow,
+	.tun_dev_create =		selinux_tun_dev_create,
+	.tun_dev_post_create = 		selinux_tun_dev_post_create,
+	.tun_dev_attach =		selinux_tun_dev_attach,
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
 	.xfrm_policy_alloc_security =	selinux_xfrm_policy_alloc,
diff --git a/security/selinux/include/av_inherit.h b/security/selinux/include/av_inherit.h
index 8377a4b..abedcd7 100644
--- a/security/selinux/include/av_inherit.h
+++ b/security/selinux/include/av_inherit.h
@@ -15,6 +15,7 @@
    S_(SECCLASS_KEY_SOCKET, socket, 0x00400000UL)
    S_(SECCLASS_UNIX_STREAM_SOCKET, socket, 0x00400000UL)
    S_(SECCLASS_UNIX_DGRAM_SOCKET, socket, 0x00400000UL)
+   S_(SECCLASS_TUN_SOCKET, socket, 0x00400000UL)
    S_(SECCLASS_IPC, ipc, 0x00000200UL)
    S_(SECCLASS_SEM, ipc, 0x00000200UL)
    S_(SECCLASS_MSGQ, ipc, 0x00000200UL)
diff --git a/security/selinux/include/av_permissions.h b/security/selinux/include/av_permissions.h
index d645192..0b41ad5 100644
--- a/security/selinux/include/av_permissions.h
+++ b/security/selinux/include/av_permissions.h
@@ -423,6 +423,28 @@
 #define UNIX_DGRAM_SOCKET__RECV_MSG               0x00080000UL
 #define UNIX_DGRAM_SOCKET__SEND_MSG               0x00100000UL
 #define UNIX_DGRAM_SOCKET__NAME_BIND              0x00200000UL
+#define TUN_SOCKET__IOCTL                         0x00000001UL
+#define TUN_SOCKET__READ                          0x00000002UL
+#define TUN_SOCKET__WRITE                         0x00000004UL
+#define TUN_SOCKET__CREATE                        0x00000008UL
+#define TUN_SOCKET__GETATTR                       0x00000010UL
+#define TUN_SOCKET__SETATTR                       0x00000020UL
+#define TUN_SOCKET__LOCK                          0x00000040UL
+#define TUN_SOCKET__RELABELFROM                   0x00000080UL
+#define TUN_SOCKET__RELABELTO                     0x00000100UL
+#define TUN_SOCKET__APPEND                        0x00000200UL
+#define TUN_SOCKET__BIND                          0x00000400UL
+#define TUN_SOCKET__CONNECT                       0x00000800UL
+#define TUN_SOCKET__LISTEN                        0x00001000UL
+#define TUN_SOCKET__ACCEPT                        0x00002000UL
+#define TUN_SOCKET__GETOPT                        0x00004000UL
+#define TUN_SOCKET__SETOPT                        0x00008000UL
+#define TUN_SOCKET__SHUTDOWN                      0x00010000UL
+#define TUN_SOCKET__RECVFROM                      0x00020000UL
+#define TUN_SOCKET__SENDTO                        0x00040000UL
+#define TUN_SOCKET__RECV_MSG                      0x00080000UL
+#define TUN_SOCKET__SEND_MSG                      0x00100000UL
+#define TUN_SOCKET__NAME_BIND                     0x00200000UL
 #define PROCESS__FORK                             0x00000001UL
 #define PROCESS__TRANSITION                       0x00000002UL
 #define PROCESS__SIGCHLD                          0x00000004UL
diff --git a/security/selinux/include/class_to_string.h b/security/selinux/include/class_to_string.h
index 21ec786..7ab9299 100644
--- a/security/selinux/include/class_to_string.h
+++ b/security/selinux/include/class_to_string.h
@@ -77,3 +77,4 @@
     S_(NULL)
     S_(NULL)
     S_("kernel_service")
+    S_("tun_socket")
diff --git a/security/selinux/include/flask.h b/security/selinux/include/flask.h
index 882f27d..f248500 100644
--- a/security/selinux/include/flask.h
+++ b/security/selinux/include/flask.h
@@ -53,6 +53,7 @@
 #define SECCLASS_PEER                                    68
 #define SECCLASS_CAPABILITY2                             69
 #define SECCLASS_KERNEL_SERVICE                          74
+#define SECCLASS_TUN_SOCKET                              75
 
 /*
  * Security identifier indices for initial entities

Re: [PATCH 1/2] lsm: Add hooks to the TUN driver

[David Miller]

From: Paul Moore <paul.moore@hp.com>
Date: Fri, 28 Aug 2009 18:12:43 -0400

> The TUN driver lacks any LSM hooks which makes it difficult for LSM modules,
> such as SELinux, to enforce access controls on network traffic generated by
> TUN users; this is particularly problematic for virtualization apps such as
> QEMU and KVM.  This patch adds three new LSM hooks designed to control the
> creation and attachment of TUN devices, the hooks are:
> 
>  * security_tun_dev_create()
>    Provides access control for the creation of new TUN devices
> 
>  * security_tun_dev_post_create()
>    Provides the ability to create the necessary socket LSM state for newly
>    created TUN devices
> 
>  * security_tun_dev_attach()
>    Provides access control for attaching to existing, persistent TUN devices
>    and the ability to update the TUN device's socket LSM state as necessary
> 
> Signed-off-by: Paul Moore <paul.moore@hp.com>
> Acked-by: Eric Paris <eparis@parisplace.org>
> Acked-by: Serge Hallyn <serue@us.ibm.com>

I'm happy if you guys merge this via the security tree,
feel free to add:

Acked-by: David S. Miller <davem@davemloft.net>

Re: [PATCH 1/2] lsm: Add hooks to the TUN driver

[James Morris]

On Fri, 28 Aug 2009, David Miller wrote:

> I'm happy if you guys merge this via the security tree,
> feel free to add:
> 
> Acked-by: David S. Miller <davem@davemloft.net>

Thanks, I'll merge it via my tree.

-- 
James Morris
<jmorris@namei.org>

Re: [PATCH 0/2] New LSM hooks for the TUN driver

[James Morris]

On Fri, 28 Aug 2009, Paul Moore wrote:

> This is the third, and hopefully final, version of the new LSM TUN hooks.  This
> version incorporates all outstanding feedback as well as my sign-off and ACKs
> from both Eric and Serge (see patches).  However, the patches are still missing
> an ACK from netdev - I haven't heard any objections but I'm not certain anyone
> from netdev has really taken a look yet.



Applied to
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6#next


-- 
James Morris
<jmorris@namei.org>