Hi, all,
Enclosed please find the new fix for the memory leak problem, incorporating
suggestions from Stephen and James.
thanks all for your help!
Catherine
--
From: [email protected]
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, sid_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.
---
include/linux/security.h | 41 +++++++++++++++++++++++++++++++++++------
include/net/af_unix.h | 6 ++----
include/net/scm.h | 29 +++++++++++++++++++++++++----
net/ipv4/ip_sockglue.c | 9 +++++++--
net/unix/af_unix.c | 33 ++++++---------------------------
security/dummy.c | 14 ++++++++++++--
security/selinux/hooks.c | 34 ++++++++++++++++++++++------------
7 files changed, 109 insertions(+), 57 deletions(-)
diff -puN include/net/scm.h~af_unix-datagram-getpeersec-ml-fix include/net/scm.h
--- linux-2.6.18-rc2/include/net/scm.h~af_unix-datagram-getpeersec-ml-fix 2006-07-22 21:28:21.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/include/net/scm.h 2006-07-24 11:19:54.000000000 -0400
@@ -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 sid; /* Passed security ID */
#endif
unsigned long seq; /* Connection seqno */
};
@@ -32,6 +32,16 @@ extern int __scm_send(struct socket *soc
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->sid);
+}
+#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 so
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 so
#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_sid_to_secctx(scm->sid, &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)
diff -puN net/unix/af_unix.c~af_unix-datagram-getpeersec-ml-fix net/unix/af_unix.c
--- linux-2.6.18-rc2/net/unix/af_unix.c~af_unix-datagram-getpeersec-ml-fix 2006-07-22 23:01:26.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/net/unix/af_unix.c 2006-07-22 23:14:15.000000000 -0400
@@ -127,30 +127,6 @@ static atomic_t unix_nr_socks = ATOMIC_I
#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)
-{
- int err;
-
- err = security_socket_getpeersec_dgram(skb, UNIXSECDATA(skb),
- UNIXSECLEN(skb));
- if (err)
- *(UNIXSECDATA(skb)) = NULL;
-}
-
-static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
-{
- scm->secdata = *UNIXSECDATA(skb);
- scm->seclen = *UNIXSECLEN(skb);
-}
-#else
-static inline void unix_get_peersec_dgram(struct sk_buff *skb)
-{ }
-
-static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
-{ }
-#endif /* CONFIG_SECURITY_NETWORK */
-
/*
* SMP locking strategy:
* hash table is protected with spinlock unix_table_lock
@@ -1323,8 +1299,9 @@ static int unix_dgram_sendmsg(struct kio
memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
if (siocb->scm->fp)
unix_attach_fds(siocb->scm, skb);
-
- unix_get_peersec_dgram(skb);
+#ifdef CONFIG_SECURITY_NETWORK
+ memcpy(UNIXSID(skb), &siocb->scm->sid, sizeof(u32));
+#endif /* CONFIG_SECURITY_NETWORK */
skb->h.raw = skb->data;
err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
@@ -1605,7 +1582,9 @@ static int unix_dgram_recvmsg(struct kio
memset(&tmp_scm, 0, sizeof(tmp_scm));
}
siocb->scm->creds = *UNIXCREDS(skb);
- unix_set_secdata(siocb->scm, skb);
+#ifdef CONFIG_SECURITY_NETWORK
+ siocb->scm->sid = *UNIXSID(skb);
+#endif /* CONFIG_SECURITY_NETWORK */
if (!(flags & MSG_PEEK))
{
diff -puN include/net/af_unix.h~af_unix-datagram-getpeersec-ml-fix include/net/af_unix.h
--- linux-2.6.18-rc2/include/net/af_unix.h~af_unix-datagram-getpeersec-ml-fix 2006-07-22 23:41:05.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/include/net/af_unix.h 2006-07-22 23:43:26.000000000 -0400
@@ -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 sid; /* 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)).sid)
#define unix_state_rlock(s) spin_lock(&unix_sk(s)->lock)
#define unix_state_runlock(s) spin_unlock(&unix_sk(s)->lock)
diff -puN include/linux/security.h~af_unix-datagram-getpeersec-ml-fix include/linux/security.h
--- linux-2.6.18-rc2/include/linux/security.h~af_unix-datagram-getpeersec-ml-fix 2006-07-23 17:49:18.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/include/linux/security.h 2006-07-24 11:16:54.000000000 -0400
@@ -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.
*
+ * @sid_to_secctx:
+ * Convert sid to security context.
+ * @sid 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 (*sid_to_secctx)(u32 sid, 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 *sid);
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(
return security_ops->netlink_recv(skb, cap);
}
+static inline int security_sid_to_secctx(u32 sid, char **secdata, u32 *seclen)
+{
+ return security_ops->sid_to_secctx(sid, 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(str
{
}
+static inline int security_sid_to_secctx(u32 sid, 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_getpee
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 *sid)
{
- return security_ops->socket_getpeersec_dgram(skb, secdata, seclen);
+ return security_ops->socket_getpeersec_dgram(sock, skb, sid);
}
static inline int security_sk_alloc(struct sock *sk, int family, gfp_t priority)
@@ -2968,8 +2998,7 @@ static inline int security_socket_getpee
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 *sid)
{
return -ENOPROTOOPT;
}
diff -puN security/selinux/hooks.c~af_unix-datagram-getpeersec-ml-fix security/selinux/hooks.c
--- linux-2.6.18-rc2/security/selinux/hooks.c~af_unix-datagram-getpeersec-ml-fix 2006-07-24 00:55:21.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/security/selinux/hooks.c 2006-07-24 23:28:05.000000000 -0400
@@ -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 *sid)
{
+ u32 peer_sid = 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
+ if (sock && (sock->sk->sk_family == PF_UNIX))
+ selinux_get_inode_sid(SOCK_INODE(sock), &peer_sid);
+ else if (skb)
peer_sid = selinux_socket_getpeer_dgram(skb);
if (peer_sid == SECSID_NULL)
- return -EINVAL;
-
- err = security_sid_to_context(peer_sid, secdata, seclen);
- if (err)
- return err;
+ err = -EINVAL;
+ *sid = peer_sid;
- 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 ta
return size;
}
+static int selinux_sid_to_secctx(u32 sid, char **secdata, u32 *seclen)
+{
+ return security_sid_to_context(sid, 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 selinu
.getprocattr = selinux_getprocattr,
.setprocattr = selinux_setprocattr,
+ .sid_to_secctx = selinux_sid_to_secctx,
+ .release_secctx = selinux_release_secctx,
+
.unix_stream_connect = selinux_socket_unix_stream_connect,
.unix_may_send = selinux_socket_unix_may_send,
diff -puN security/dummy.c~af_unix-datagram-getpeersec-ml-fix security/dummy.c
--- linux-2.6.18-rc2/security/dummy.c~af_unix-datagram-getpeersec-ml-fix 2006-07-24 01:01:07.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/security/dummy.c 2006-07-24 11:30:36.000000000 -0400
@@ -791,8 +791,7 @@ static int dummy_socket_getpeersec_strea
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 *sid)
{
return -ENOPROTOOPT;
}
@@ -876,6 +875,15 @@ static int dummy_setprocattr(struct task
return -EINVAL;
}
+static int dummy_sid_to_secctx(u32 sid, 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
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, sid_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);
diff -puN net/ipv4/ip_sockglue.c~af_unix-datagram-getpeersec-ml-fix net/ipv4/ip_sockglue.c
--- linux-2.6.18-rc2/net/ipv4/ip_sockglue.c~af_unix-datagram-getpeersec-ml-fix 2006-07-24 18:42:18.000000000 -0400
+++ linux-2.6.18-rc2-cxzhang/net/ipv4/ip_sockglue.c 2006-07-24 18:42:25.000000000 -0400
@@ -112,14 +112,19 @@ static void ip_cmsg_recv_retopts(struct
static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
{
char *secdata;
- u32 seclen;
+ u32 seclen, sid;
int err;
- err = security_socket_getpeersec_dgram(skb, &secdata, &seclen);
+ err = security_socket_getpeersec_dgram(NULL, skb, &sid);
+ if (err)
+ return;
+
+ err = security_sid_to_secctx(sid, &secdata, &seclen);
if (err)
return;
put_cmsg(msg, SOL_IP, SCM_SECURITY, seclen, secdata);
+ security_release_secctx(secdata, seclen);
}
_
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