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authorPaul Moore <paul.moore@hp.com>2009-08-28 18:12:43 -0400
committerJames Morris <jmorris@namei.org>2009-09-01 08:29:48 +1000
commit2b980dbd77d229eb60588802162c9659726b11f4 (patch)
tree78a7f734d0721029e4b4c961ca61d35abe9e6dbc
parentd8e180dcd5bbbab9cd3ff2e779efcf70692ef541 (diff)
downloadlinux-stericsson-2b980dbd77d229eb60588802162c9659726b11f4.tar.gz
lsm: Add hooks to the TUN driver
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> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: James Morris <jmorris@namei.org>
-rw-r--r--drivers/net/tun.c22
-rw-r--r--include/linux/security.h31
-rw-r--r--security/capability.c19
-rw-r--r--security/security.c18
4 files changed, 83 insertions, 7 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 42b6c6319bc2..87214a257d2a 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 a16d6b7c4ebe..40ba39ea68ce 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -998,6 +998,17 @@ 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.
*
@@ -1597,6 +1608,9 @@ 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
@@ -2586,6 +2600,9 @@ 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,
@@ -2736,6 +2753,20 @@ 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 1b943f54b2ea..06400cf07757 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -706,10 +706,26 @@ 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
@@ -1026,6 +1042,9 @@ 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 0e993f42ce3d..f88eaf6b14cc 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1117,6 +1117,24 @@ 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