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NetLabel: SELinux cleanups
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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>
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Paul Moore authored and David S. Miller committed Dec 3, 2006
1 parent 9bb5fd2 commit 9f2ad66
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Showing 4 changed files with 86 additions and 54 deletions.
10 changes: 5 additions & 5 deletions security/selinux/hooks.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3140,9 +3140,7 @@ static int selinux_socket_post_create(struct socket *sock, int family,
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;
Expand Down Expand Up @@ -3661,7 +3659,7 @@ static void selinux_sk_clone_security(const struct sock *sk, struct sock *newsk)
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)
Expand Down Expand Up @@ -3730,7 +3728,9 @@ static void selinux_inet_csk_clone(struct sock *newsk,
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,
Expand Down
2 changes: 2 additions & 0 deletions security/selinux/include/objsec.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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"

Expand Down Expand Up @@ -108,6 +109,7 @@ struct sk_security_struct {
NLBL_REQUIRE,
NLBL_LABELED,
} nlbl_state;
spinlock_t nlbl_lock; /* protects nlbl_state */
#endif
};

Expand Down
21 changes: 13 additions & 8 deletions security/selinux/include/selinux_netlabel.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -38,19 +38,19 @@

#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,
struct sk_buff *skb,
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,
Expand All @@ -62,9 +62,7 @@ static inline void selinux_netlbl_cache_invalidate(void)
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;
}
Expand Down Expand Up @@ -98,14 +96,21 @@ static inline u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb)
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)
{
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)
{
Expand Down
107 changes: 66 additions & 41 deletions security/selinux/ss/services.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -2435,7 +2436,9 @@ static int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
*
* 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)
Expand Down Expand Up @@ -2472,15 +2475,37 @@ static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
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;
netlbl_secattr_destroy(&secattr);
return rc;
}

/**
* 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
Expand All @@ -2494,14 +2519,13 @@ static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
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
*
Expand All @@ -2510,41 +2534,41 @@ void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
* @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;
}

/**
Expand All @@ -2566,8 +2590,12 @@ void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)

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 &&
Expand All @@ -2579,12 +2607,12 @@ void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
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();
}

/**
Expand Down Expand Up @@ -2625,25 +2653,24 @@ u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb, u32 sock_sid)
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;
}
Expand Down Expand Up @@ -2754,12 +2781,10 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock,
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);
Expand All @@ -2768,7 +2793,7 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock,
rc = -EACCES;
netlbl_secattr_destroy(&secattr);
}
mutex_unlock(&isec->lock);
rcu_read_unlock();

return rc;
}
Expand Down

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