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Commit dc49c1f9 authored by Catherine Zhang's avatar Catherine Zhang Committed by David S. Miller
Browse files

[AF_UNIX]: Kernel memory leak fix for af_unix datagram getpeersec patch 



From: Catherine Zhang <cxzhang@watson.ibm.com>

This patch implements a cleaner fix for the memory leak problem of the
original unix datagram getpeersec patch.  Instead of creating a
security context each time a unix datagram is sent, we only create the
security context when the receiver requests it.

This new design requires modification of the current
unix_getsecpeer_dgram LSM hook and addition of two new hooks, namely,
secid_to_secctx and release_secctx.  The former retrieves the security
context and the latter releases it.  A hook is required for releasing
the security context because it is up to the security module to decide
how that's done.  In the case of Selinux, it's a simple kfree
operation.

Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2b7e24b6

include/linux/security.h

+35 −6
Original line number Diff line number Diff line
@@ -1109,6 +1109,16 @@ struct swap_info_struct; 
 *	@name contains the name of the security module being unstacked.

 *	@ops contains a pointer to the struct security_operations of the module to unstack.

 * 

 * @secid_to_secctx:

 *	Convert secid to security context.

 *	@secid contains the security ID.

 *	@secdata contains the pointer that stores the converted security context.

 *

 * @release_secctx:

 *	Release the security context.

 *	@secdata contains the security context.

 *	@seclen contains the length of the security context.

 *

 * This is the main security structure.

 */

struct security_operations {
@@ -1289,6 +1299,8 @@ struct security_operations { 


 	int (*getprocattr)(struct task_struct *p, char *name, void *value, size_t size);

 	int (*setprocattr)(struct task_struct *p, char *name, void *value, size_t size);

	int (*secid_to_secctx)(u32 secid, char **secdata, u32 *seclen);

	void (*release_secctx)(char *secdata, u32 seclen);



#ifdef CONFIG_SECURITY_NETWORK

	int (*unix_stream_connect) (struct socket * sock,
@@ -1317,7 +1329,7 @@ struct security_operations { 
	int (*socket_shutdown) (struct socket * sock, int how);

	int (*socket_sock_rcv_skb) (struct sock * sk, struct sk_buff * skb);

	int (*socket_getpeersec_stream) (struct socket *sock, char __user *optval, int __user *optlen, unsigned len);

	int (*socket_getpeersec_dgram) (struct sk_buff *skb, char **secdata, u32 *seclen);

	int (*socket_getpeersec_dgram) (struct socket *sock, struct sk_buff *skb, u32 *secid);

	int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority);

	void (*sk_free_security) (struct sock *sk);

	unsigned int (*sk_getsid) (struct sock *sk, struct flowi *fl, u8 dir);
@@ -2059,6 +2071,16 @@ static inline int security_netlink_recv(struct sk_buff * skb, int cap) 
	return security_ops->netlink_recv(skb, cap);

}



static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)

{

	return security_ops->secid_to_secctx(secid, secdata, seclen);

}



static inline void security_release_secctx(char *secdata, u32 seclen)

{

	return security_ops->release_secctx(secdata, seclen);

}



/* prototypes */

extern int security_init	(void);

extern int register_security	(struct security_operations *ops);
@@ -2725,6 +2747,15 @@ static inline void securityfs_remove(struct dentry *dentry) 
{

}



static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)

{

	return -EOPNOTSUPP;

}



static inline void security_release_secctx(char *secdata, u32 seclen)

{

	return -EOPNOTSUPP;

}

#endif	/* CONFIG_SECURITY */



#ifdef CONFIG_SECURITY_NETWORK
@@ -2840,10 +2871,9 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __ 
	return security_ops->socket_getpeersec_stream(sock, optval, optlen, len);

}



static inline int security_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata,

						   u32 *seclen)

static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)

{

	return security_ops->socket_getpeersec_dgram(skb, secdata, seclen);

	return security_ops->socket_getpeersec_dgram(sock, skb, secid);

}



static inline int security_sk_alloc(struct sock *sk, int family, gfp_t priority)
@@ -2968,8 +2998,7 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __ 
	return -ENOPROTOOPT;

}



static inline int security_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata,

						   u32 *seclen)

static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)

{

	return -ENOPROTOOPT;

}

include/net/af_unix.h

+2 −4
Original line number Diff line number Diff line
@@ -54,15 +54,13 @@ struct unix_skb_parms { 
	struct ucred		creds;		/* Skb credentials	*/

	struct scm_fp_list	*fp;		/* Passed files		*/

#ifdef CONFIG_SECURITY_NETWORK

	char			*secdata;	/* Security context	*/

	u32			seclen;		/* Security length	*/

	u32			secid;		/* Security ID		*/

#endif

};



#define UNIXCB(skb) 	(*(struct unix_skb_parms*)&((skb)->cb))

#define UNIXCREDS(skb)	(&UNIXCB((skb)).creds)

#define UNIXSECDATA(skb)	(&UNIXCB((skb)).secdata)

#define UNIXSECLEN(skb)		(&UNIXCB((skb)).seclen)

#define UNIXSID(skb)	(&UNIXCB((skb)).secid)



#define unix_state_rlock(s)	spin_lock(&unix_sk(s)->lock)

#define unix_state_runlock(s)	spin_unlock(&unix_sk(s)->lock)

include/net/scm.h

+25 −4
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <linux/limits.h>

#include <linux/net.h>

#include <linux/security.h>



/* Well, we should have at least one descriptor open

 * to accept passed FDs 8)
@@ -20,8 +21,7 @@ struct scm_cookie 
	struct ucred		creds;		/* Skb credentials	*/

	struct scm_fp_list	*fp;		/* Passed files		*/

#ifdef CONFIG_SECURITY_NETWORK

	char			*secdata;	/* Security context	*/

	u32			seclen;		/* Security length	*/

	u32			secid;		/* Passed security ID 	*/

#endif

	unsigned long		seq;		/* Connection seqno	*/

};
@@ -32,6 +32,16 @@ extern int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie 
extern void __scm_destroy(struct scm_cookie *scm);

extern struct scm_fp_list * scm_fp_dup(struct scm_fp_list *fpl);



#ifdef CONFIG_SECURITY_NETWORK

static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)

{

	security_socket_getpeersec_dgram(sock, NULL, &scm->secid);

}

#else

static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)

{ }

#endif /* CONFIG_SECURITY_NETWORK */



static __inline__ void scm_destroy(struct scm_cookie *scm)

{

	if (scm && scm->fp)
@@ -47,6 +57,7 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, 
	scm->creds.pid = p->tgid;

	scm->fp = NULL;

	scm->seq = 0;

	unix_get_peersec_dgram(sock, scm);

	if (msg->msg_controllen <= 0)

		return 0;

	return __scm_send(sock, msg, scm);
@@ -55,8 +66,18 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg, 
#ifdef CONFIG_SECURITY_NETWORK

static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)

{

	if (test_bit(SOCK_PASSSEC, &sock->flags) && scm->secdata != NULL)

		put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, scm->seclen, scm->secdata);

	char *secdata;

	u32 seclen;

	int err;



	if (test_bit(SOCK_PASSSEC, &sock->flags)) {

		err = security_secid_to_secctx(scm->secid, &secdata, &seclen);



		if (!err) {

			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);

			security_release_secctx(secdata, seclen);

		}

	}

}

#else

static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)

net/ipv4/ip_sockglue.c

+7 −2
Original line number Diff line number Diff line
@@ -112,14 +112,19 @@ static void ip_cmsg_recv_retopts(struct msghdr *msg, struct sk_buff *skb) 
static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)

{

	char *secdata;

	u32 seclen;

	u32 seclen, secid;

	int err;



	err = security_socket_getpeersec_dgram(skb, &secdata, &seclen);

	err = security_socket_getpeersec_dgram(NULL, skb, &secid);

	if (err)

		return;



	err = security_secid_to_secctx(secid, &secdata, &seclen);

	if (err)

		return;



	put_cmsg(msg, SOL_IP, SCM_SECURITY, seclen, secdata);

	security_release_secctx(secdata, seclen);

}

net/unix/af_unix.c

+5 −12
Original line number Diff line number Diff line
@@ -128,23 +128,17 @@ static atomic_t unix_nr_socks = ATOMIC_INIT(0); 
#define UNIX_ABSTRACT(sk)	(unix_sk(sk)->addr->hash != UNIX_HASH_SIZE)



#ifdef CONFIG_SECURITY_NETWORK

static void unix_get_peersec_dgram(struct sk_buff *skb)

static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)

{

	int err;



	err = security_socket_getpeersec_dgram(skb, UNIXSECDATA(skb),

					       UNIXSECLEN(skb));

	if (err)

		*(UNIXSECDATA(skb)) = NULL;

	memcpy(UNIXSID(skb), &scm->secid, sizeof(u32));

}



static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)

{

	scm->secdata = *UNIXSECDATA(skb);

	scm->seclen = *UNIXSECLEN(skb);

	scm->secid = *UNIXSID(skb);

}

#else

static inline void unix_get_peersec_dgram(struct sk_buff *skb)

static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)

{ }



static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
@@ -1322,8 +1316,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock, 
	memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));

	if (siocb->scm->fp)

		unix_attach_fds(siocb->scm, skb);



	unix_get_peersec_dgram(skb);

	unix_get_secdata(siocb->scm, skb);



	skb->h.raw = skb->data;

	err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);