diff mbox

[RFC,v1,2/2] selinux: Support for the new TUN LSM hooks

Message ID 20090804212204.10798.53727.stgit@flek.lan
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Paul Moore Aug. 4, 2009, 9:22 p.m. UTC
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.

This patch also includes a new policy capability, tun_perms, to ensure that
the new access controls do not affect older SELinux policies.

--

NOTE: This relies on some changes to the policy to add the new object class
      and its associated permissions, I will ensure that the policy is sorted
      and merged before pushing this patch upstream.  Also, you will notice
      that the new tun_socket object class simply inherits the base socket
      object class, thoughts?
---

 security/selinux/hooks.c                   |   76 +++++++++++++++++++++++++++-
 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 
 security/selinux/include/security.h        |    2 +
 security/selinux/selinuxfs.c               |    3 +
 security/selinux/ss/services.c             |    3 +
 8 files changed, 106 insertions(+), 3 deletions(-)


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Comments

Eric Paris Aug. 5, 2009, 1:06 p.m. UTC | #1
On Tue, Aug 4, 2009 at 5:22 PM, Paul Moore<paul.moore@hp.com> wrote:
> 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.
>
> This patch also includes a new policy capability, tun_perms, to ensure that
> the new access controls do not affect older SELinux policies.

I think we finally have the first patch where the 'handle_unknown'
stuff fits better than the policy capabilities work!  First time for
everything!  I'd suggest dropping the policy capability all together
and the checks will be applied when the class and perm is defined in
the loaded policy.  If the class+perm isn't defined in policy the
policy handle_unknown setting will define the result of the security
check.

whoo hoo, saves 32bits of memory and 2 branches on low use operations!

-Eric
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diff mbox

Patch

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 15c2a08..6ba99c2 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>
  *
@@ -4296,6 +4296,75 @@  static void selinux_req_classify_flow(const struct request_sock *req,
 	fl->secid = req->secid;
 }
 
+static int selinux_tun_dev_create(void)
+{
+	u32 sid;
+	int err;
+
+	err = cap_tun_dev_create();
+	if (err)
+		return err;
+
+	if (!selinux_policycap_tunperm)
+		return 0;
+
+	/* 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 understand of why this socket is special */
+
+	sid = current_sid();
+	return avc_has_perm(sid, sid, SECCLASS_TUN_SOCKET, TUN_SOCKET__CREATE,
+			    NULL);
+}
+
+static void selinux_tun_dev_post_create(struct sock *tun_sk)
+{
+	struct sk_security_struct *sksec = tun_sk->sk_security;
+
+	/* see the comments in _tun_dev_create() about why we don't use the
+	 * sockcreate SID here */
+
+	/* 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 */
+
+	sksec->sid = current_sid();
+	sksec->sclass = SECCLASS_TUN_SOCKET;
+}
+
+static int selinux_tun_dev_attach(struct sock *tun_sk)
+{
+	struct sk_security_struct *tun_sksec = tun_sk->sk_security;
+	u32 sid;
+	int err;
+
+	err = cap_tun_dev_attach();
+	if (err)
+		return err;
+
+	if (!selinux_policycap_tunperm)
+		return 0;
+
+	sid = current_sid();
+	err = avc_has_perm(sid, tun_sksec->sid, SECCLASS_TUN_SOCKET,
+			   TUN_SOCKET__RELABELFROM, NULL);
+	if (err)
+		return err;
+	err = avc_has_perm(sid, sid, SECCLASS_RAWIP_SOCKET,
+			   TUN_SOCKET__RELABELTO, NULL);
+	if (err)
+		return err;
+	tun_sksec->sid = sid;
+
+	return 0;
+}
+
 static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
 {
 	int err = 0;
@@ -5464,6 +5533,9 @@  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
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index ca83579..188af8d 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -63,12 +63,14 @@  extern int selinux_mls_enabled;
 enum {
 	POLICYDB_CAPABILITY_NETPEER,
 	POLICYDB_CAPABILITY_OPENPERM,
+	POLICYDB_CAPABILITY_TUNPERM,
 	__POLICYDB_CAPABILITY_MAX
 };
 #define POLICYDB_CAPABILITY_MAX (__POLICYDB_CAPABILITY_MAX - 1)
 
 extern int selinux_policycap_netpeer;
 extern int selinux_policycap_openperm;
+extern int selinux_policycap_tunperm;
 
 /*
  * type_datum properties
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index b4fc506..770e059 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -42,7 +42,8 @@ 
 /* Policy capability filenames */
 static char *policycap_names[] = {
 	"network_peer_controls",
-	"open_perms"
+	"open_perms",
+	"tun_perms"
 };
 
 unsigned int selinux_checkreqprot = CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE;
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 500e6f7..adbe6d5 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -64,6 +64,7 @@  unsigned int policydb_loaded_version;
 
 int selinux_policycap_netpeer;
 int selinux_policycap_openperm;
+int selinux_policycap_tunperm;
 
 /*
  * This is declared in avc.c
@@ -1593,6 +1594,8 @@  static void security_load_policycaps(void)
 						  POLICYDB_CAPABILITY_NETPEER);
 	selinux_policycap_openperm = ebitmap_get_bit(&policydb.policycaps,
 						  POLICYDB_CAPABILITY_OPENPERM);
+	selinux_policycap_tunperm = ebitmap_get_bit(&policydb.policycaps,
+						   POLICYDB_CAPABILITY_TUNPERM);
 }
 
 extern void selinux_complete_init(void);