[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>
diff --git a/include/linux/security.h b/include/linux/security.h
index f753038..aa5b804 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1109,6 +1109,16 @@
* @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 @@
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 @@
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 @@
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 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 @@
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 @@
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;
}
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 2fec827c..c0398f5 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -54,15 +54,13 @@
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)
diff --git a/include/net/scm.h b/include/net/scm.h
index 02daa09..5637d5e 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -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 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 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 @@
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 @@
#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)