[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/security/selinux/hooks.c b/security/selinux/hooks.c
index a91c961..5d1b8c7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3524,25 +3524,21 @@
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 @@
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 @@
.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,
