NetLabel: SELinux cleanups
This patch does a lot of cleanup in the SELinux NetLabel support code. A
summary of the changes include:
* Use RCU locking for the NetLabel state variable in the skk_security_struct
instead of using the inode_security_struct mutex.
* Remove unnecessary parameters in selinux_netlbl_socket_post_create().
* Rename selinux_netlbl_sk_clone_security() to
selinux_netlbl_sk_security_clone() to better fit the other NetLabel
sk_security functions.
* Improvements to selinux_netlbl_inode_permission() to help reduce the cost of
the common case.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0cf9874..975c0df 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3140,9 +3140,7 @@
if (sock->sk) {
sksec = sock->sk->sk_security;
sksec->sid = isec->sid;
- err = selinux_netlbl_socket_post_create(sock,
- family,
- isec->sid);
+ err = selinux_netlbl_socket_post_create(sock);
}
return err;
@@ -3661,7 +3659,7 @@
newssec->sid = ssec->sid;
newssec->peer_sid = ssec->peer_sid;
- selinux_netlbl_sk_clone_security(ssec, newssec);
+ selinux_netlbl_sk_security_clone(ssec, newssec);
}
static void selinux_sk_getsecid(struct sock *sk, u32 *secid)
@@ -3730,7 +3728,9 @@
So we will wait until sock_graft to do it, by which
time it will have been created and available. */
- selinux_netlbl_sk_security_init(newsksec, req->rsk_ops->family);
+ /* We don't need to take any sort of lock here as we are the only
+ * thread with access to newsksec */
+ selinux_netlbl_sk_security_reset(newsksec, req->rsk_ops->family);
}
static void selinux_inet_conn_established(struct sock *sk,
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index ef2267f..91b88f0 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -23,6 +23,7 @@
#include <linux/fs.h>
#include <linux/binfmts.h>
#include <linux/in.h>
+#include <linux/spinlock.h>
#include "flask.h"
#include "avc.h"
@@ -108,6 +109,7 @@
NLBL_REQUIRE,
NLBL_LABELED,
} nlbl_state;
+ spinlock_t nlbl_lock; /* protects nlbl_state */
#endif
};
diff --git a/security/selinux/include/selinux_netlabel.h b/security/selinux/include/selinux_netlabel.h
index 9de10cc..57943f4 100644
--- a/security/selinux/include/selinux_netlabel.h
+++ b/security/selinux/include/selinux_netlabel.h
@@ -38,9 +38,7 @@
#ifdef CONFIG_NETLABEL
void selinux_netlbl_cache_invalidate(void);
-int selinux_netlbl_socket_post_create(struct socket *sock,
- int sock_family,
- u32 sid);
+int selinux_netlbl_socket_post_create(struct socket *sock);
void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock);
u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb, u32 sock_sid);
int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
@@ -48,9 +46,11 @@
struct avc_audit_data *ad);
u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock);
u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb);
+void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
+ int family);
void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
int family);
-void selinux_netlbl_sk_clone_security(struct sk_security_struct *ssec,
+void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
struct sk_security_struct *newssec);
int selinux_netlbl_inode_permission(struct inode *inode, int mask);
int selinux_netlbl_socket_setsockopt(struct socket *sock,
@@ -62,9 +62,7 @@
return;
}
-static inline int selinux_netlbl_socket_post_create(struct socket *sock,
- int sock_family,
- u32 sid)
+static inline int selinux_netlbl_socket_post_create(struct socket *sock)
{
return 0;
}
@@ -98,6 +96,13 @@
return SECSID_NULL;
}
+static inline void selinux_netlbl_sk_security_reset(
+ struct sk_security_struct *ssec,
+ int family)
+{
+ return;
+}
+
static inline void selinux_netlbl_sk_security_init(
struct sk_security_struct *ssec,
int family)
@@ -105,7 +110,7 @@
return;
}
-static inline void selinux_netlbl_sk_clone_security(
+static inline void selinux_netlbl_sk_security_clone(
struct sk_security_struct *ssec,
struct sk_security_struct *newssec)
{
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 1f5bbb2..b66b454 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -33,6 +33,7 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/sched.h>
@@ -2435,7 +2436,9 @@
*
* Description:
* Attempt to label a socket using the NetLabel mechanism using the given
- * SID. Returns zero values on success, negative values on failure.
+ * SID. Returns zero values on success, negative values on failure. The
+ * caller is responsibile for calling rcu_read_lock() before calling this
+ * this function and rcu_read_unlock() after this function returns.
*
*/
static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
@@ -2472,8 +2475,11 @@
secattr.flags |= NETLBL_SECATTR_MLS_CAT;
rc = netlbl_socket_setattr(sock, &secattr);
- if (rc == 0)
+ if (rc == 0) {
+ spin_lock(&sksec->nlbl_lock);
sksec->nlbl_state = NLBL_LABELED;
+ spin_unlock(&sksec->nlbl_lock);
+ }
netlbl_socket_setsid_return:
POLICY_RDUNLOCK;
@@ -2482,6 +2488,25 @@
}
/**
+ * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
+ * @ssec: the sk_security_struct
+ * @family: the socket family
+ *
+ * Description:
+ * Called when the NetLabel state of a sk_security_struct needs to be reset.
+ * The caller is responsibile for all the NetLabel sk_security_struct locking.
+ *
+ */
+void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
+ int family)
+{
+ if (family == PF_INET)
+ ssec->nlbl_state = NLBL_REQUIRE;
+ else
+ ssec->nlbl_state = NLBL_UNSET;
+}
+
+/**
* selinux_netlbl_sk_security_init - Setup the NetLabel fields
* @ssec: the sk_security_struct
* @family: the socket family
@@ -2494,14 +2519,13 @@
void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
int family)
{
- if (family == PF_INET)
- ssec->nlbl_state = NLBL_REQUIRE;
- else
- ssec->nlbl_state = NLBL_UNSET;
+ /* No locking needed, we are the only one who has access to ssec */
+ selinux_netlbl_sk_security_reset(ssec, family);
+ spin_lock_init(&ssec->nlbl_lock);
}
/**
- * selinux_netlbl_sk_clone_security - Copy the NetLabel fields
+ * selinux_netlbl_sk_security_clone - Copy the NetLabel fields
* @ssec: the original sk_security_struct
* @newssec: the cloned sk_security_struct
*
@@ -2510,41 +2534,41 @@
* @newssec.
*
*/
-void selinux_netlbl_sk_clone_security(struct sk_security_struct *ssec,
+void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
struct sk_security_struct *newssec)
{
+ /* We don't need to take newssec->nlbl_lock because we are the only
+ * thread with access to newssec, but we do need to take the RCU read
+ * lock as other threads could have access to ssec */
+ rcu_read_lock();
+ selinux_netlbl_sk_security_reset(newssec, ssec->sk->sk_family);
newssec->sclass = ssec->sclass;
- if (ssec->nlbl_state != NLBL_UNSET)
- newssec->nlbl_state = NLBL_REQUIRE;
- else
- newssec->nlbl_state = NLBL_UNSET;
+ rcu_read_unlock();
}
/**
* selinux_netlbl_socket_post_create - Label a socket using NetLabel
* @sock: the socket to label
- * @sock_family: the socket family
- * @sid: the SID to use
*
* Description:
* Attempt to label a socket using the NetLabel mechanism using the given
* SID. Returns zero values on success, negative values on failure.
*
*/
-int selinux_netlbl_socket_post_create(struct socket *sock,
- int sock_family,
- u32 sid)
+int selinux_netlbl_socket_post_create(struct socket *sock)
{
+ int rc = 0;
struct inode_security_struct *isec = SOCK_INODE(sock)->i_security;
struct sk_security_struct *sksec = sock->sk->sk_security;
sksec->sclass = isec->sclass;
- if (sock_family != PF_INET)
- return 0;
+ rcu_read_lock();
+ if (sksec->nlbl_state == NLBL_REQUIRE)
+ rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
+ rcu_read_unlock();
- sksec->nlbl_state = NLBL_REQUIRE;
- return selinux_netlbl_socket_setsid(sock, sid);
+ return rc;
}
/**
@@ -2566,8 +2590,12 @@
sksec->sclass = isec->sclass;
- if (sk->sk_family != PF_INET)
+ rcu_read_lock();
+
+ if (sksec->nlbl_state != NLBL_REQUIRE) {
+ rcu_read_unlock();
return;
+ }
netlbl_secattr_init(&secattr);
if (netlbl_sock_getattr(sk, &secattr) == 0 &&
@@ -2579,12 +2607,12 @@
sksec->peer_sid = nlbl_peer_sid;
netlbl_secattr_destroy(&secattr);
- sksec->nlbl_state = NLBL_REQUIRE;
-
/* Try to set the NetLabel on the socket to save time later, if we fail
* here we will pick up the pieces in later calls to
* selinux_netlbl_inode_permission(). */
selinux_netlbl_socket_setsid(sock, sksec->sid);
+
+ rcu_read_unlock();
}
/**
@@ -2625,25 +2653,24 @@
int selinux_netlbl_inode_permission(struct inode *inode, int mask)
{
int rc;
- struct inode_security_struct *isec;
struct sk_security_struct *sksec;
struct socket *sock;
- if (!S_ISSOCK(inode->i_mode))
+ if (!S_ISSOCK(inode->i_mode) ||
+ ((mask & (MAY_WRITE | MAY_APPEND)) == 0))
return 0;
-
sock = SOCKET_I(inode);
- isec = inode->i_security;
sksec = sock->sk->sk_security;
- mutex_lock(&isec->lock);
- if (unlikely(sksec->nlbl_state == NLBL_REQUIRE &&
- (mask & (MAY_WRITE | MAY_APPEND)))) {
- lock_sock(sock->sk);
- rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
- release_sock(sock->sk);
- } else
- rc = 0;
- mutex_unlock(&isec->lock);
+
+ rcu_read_lock();
+ if (sksec->nlbl_state != NLBL_REQUIRE) {
+ rcu_read_unlock();
+ return 0;
+ }
+ lock_sock(sock->sk);
+ rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
+ release_sock(sock->sk);
+ rcu_read_unlock();
return rc;
}
@@ -2754,12 +2781,10 @@
int optname)
{
int rc = 0;
- struct inode *inode = SOCK_INODE(sock);
struct sk_security_struct *sksec = sock->sk->sk_security;
- struct inode_security_struct *isec = inode->i_security;
struct netlbl_lsm_secattr secattr;
- mutex_lock(&isec->lock);
+ rcu_read_lock();
if (level == IPPROTO_IP && optname == IP_OPTIONS &&
sksec->nlbl_state == NLBL_LABELED) {
netlbl_secattr_init(&secattr);
@@ -2768,7 +2793,7 @@
rc = -EACCES;
netlbl_secattr_destroy(&secattr);
}
- mutex_unlock(&isec->lock);
+ rcu_read_unlock();
return rc;
}