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[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:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Catherine Zhang 2006-08-02 14:12:06 -07:00 committed by David S. Miller
parent 2b7e24b66d
commit dc49c1f94e
7 changed files with 110 additions and 44 deletions
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41
include/linux/security.h
View File

@ -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;
}

6
include/net/af_unix.h
View File

@ -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)

29
include/net/scm.h
View File

@ -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)

9
net/ipv4/ip_sockglue.c
View File

@ -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);
}

17
net/unix/af_unix.c
View File

@ -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);

14
security/dummy.c
View File

@ -791,8 +791,7 @@ static int dummy_socket_getpeersec_stream(struct socket *sock, char __user *optv
return -ENOPROTOOPT;
}
static int dummy_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata,
u32 *seclen)
static int dummy_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)
{
return -ENOPROTOOPT;
}
@ -876,6 +875,15 @@ static int dummy_setprocattr(struct task_struct *p, char *name, void *value, siz
return -EINVAL;
}
static int dummy_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
{
return -EOPNOTSUPP;
}
static void dummy_release_secctx(char *secdata, u32 seclen)
{
}
#ifdef CONFIG_KEYS
static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx,
unsigned long flags)
@ -1028,6 +1036,8 @@ void security_fixup_ops (struct security_operations *ops)
set_to_dummy_if_null(ops, d_instantiate);
set_to_dummy_if_null(ops, getprocattr);
set_to_dummy_if_null(ops, setprocattr);
set_to_dummy_if_null(ops, secid_to_secctx);
set_to_dummy_if_null(ops, release_secctx);
#ifdef CONFIG_SECURITY_NETWORK
set_to_dummy_if_null(ops, unix_stream_connect);
set_to_dummy_if_null(ops, unix_may_send);

38
security/selinux/hooks.c
View File

@ -3524,25 +3524,21 @@ out:
return err;
}
static int selinux_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, u32 *seclen)
static int selinux_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)
{
u32 peer_secid = SECSID_NULL;
int err = 0;
u32 peer_sid;
if (skb->sk->sk_family == PF_UNIX)
selinux_get_inode_sid(SOCK_INODE(skb->sk->sk_socket),
&peer_sid);
else
peer_sid = selinux_socket_getpeer_dgram(skb);
if (sock && (sock->sk->sk_family == PF_UNIX))
selinux_get_inode_sid(SOCK_INODE(sock), &peer_secid);
else if (skb)
peer_secid = selinux_socket_getpeer_dgram(skb);
if (peer_sid == SECSID_NULL)
return -EINVAL;
if (peer_secid == SECSID_NULL)
err = -EINVAL;
*secid = peer_secid;
err = security_sid_to_context(peer_sid, secdata, seclen);
if (err)
return err;
return 0;
return err;
}
static int selinux_sk_alloc_security(struct sock *sk, int family, gfp_t priority)
@ -4407,6 +4403,17 @@ static int selinux_setprocattr(struct task_struct *p,
return size;
}
static int selinux_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
{
return security_sid_to_context(secid, secdata, seclen);
}
static void selinux_release_secctx(char *secdata, u32 seclen)
{
if (secdata)
kfree(secdata);
}
#ifdef CONFIG_KEYS
static int selinux_key_alloc(struct key *k, struct task_struct *tsk,
@ -4587,6 +4594,9 @@ static struct security_operations selinux_ops = {
.getprocattr = selinux_getprocattr,
.setprocattr = selinux_setprocattr,
.secid_to_secctx = selinux_secid_to_secctx,
.release_secctx = selinux_release_secctx,
.unix_stream_connect = selinux_socket_unix_stream_connect,
.unix_may_send = selinux_socket_unix_may_send,