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authorPaul Moore <pmoore@redhat.com>2013-12-03 11:14:04 -0500
committerPaul Moore <pmoore@redhat.com>2013-12-04 16:06:47 -0500
commitda2ea0d05671f878196cc949906aa89d15c567db (patch)
treea9067db90c8d2da60f1a38ba649f793a09620f8d /security
parent8e645c345a4cf6b8b13054b4ec2f6371f05876a9 (diff)
downloadlinux-da2ea0d05671f878196cc949906aa89d15c567db.tar.gz
selinux: handle TCP SYN-ACK packets correctly in selinux_ip_output()
In selinux_ip_output() we always label packets based on the parent socket. While this approach works in almost all cases, it doesn't work in the case of TCP SYN-ACK packets when the correct label is not the label of the parent socket, but rather the label of the larval socket represented by the request_sock struct. Unfortunately, since the request_sock isn't queued on the parent socket until *after* the SYN-ACK packet is sent, we can't lookup the request_sock to determine the correct label for the packet; at this point in time the best we can do is simply pass/NF_ACCEPT the packet. It must be said that simply passing the packet without any explicit labeling action, while far from ideal, is not terrible as the SYN-ACK packet will inherit any IP option based labeling from the initial connection request so the label *should* be correct and all our access controls remain in place so we shouldn't have to worry about information leaks. Reported-by: Janak Desai <Janak.Desai@gtri.gatech.edu> Tested-by: Janak Desai <Janak.Desai@gtri.gatech.edu> Cc: stable@vger.kernel.org Signed-off-by: Paul Moore <pmoore@redhat.com>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/hooks.c25
1 files changed, 23 insertions, 2 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 777ee98273d..877bab748c8 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -53,6 +53,7 @@
#include <net/ip.h> /* for local_port_range[] */
#include <net/sock.h>
#include <net/tcp.h> /* struct or_callable used in sock_rcv_skb */
+#include <net/inet_connection_sock.h>
#include <net/net_namespace.h>
#include <net/netlabel.h>
#include <linux/uaccess.h>
@@ -4731,6 +4732,7 @@ static unsigned int selinux_ipv6_forward(unsigned int hooknum,
static unsigned int selinux_ip_output(struct sk_buff *skb,
u16 family)
{
+ struct sock *sk;
u32 sid;
if (!netlbl_enabled())
@@ -4739,8 +4741,27 @@ static unsigned int selinux_ip_output(struct sk_buff *skb,
/* we do this in the LOCAL_OUT path and not the POST_ROUTING path
* because we want to make sure we apply the necessary labeling
* before IPsec is applied so we can leverage AH protection */
- if (skb->sk) {
- struct sk_security_struct *sksec = skb->sk->sk_security;
+ sk = skb->sk;
+ if (sk) {
+ struct sk_security_struct *sksec;
+
+ if (sk->sk_state == TCP_LISTEN)
+ /* if the socket is the listening state then this
+ * packet is a SYN-ACK packet which means it needs to
+ * be labeled based on the connection/request_sock and
+ * not the parent socket. unfortunately, we can't
+ * lookup the request_sock yet as it isn't queued on
+ * the parent socket until after the SYN-ACK is sent.
+ * the "solution" is to simply pass the packet as-is
+ * as any IP option based labeling should be copied
+ * from the initial connection request (in the IP
+ * layer). it is far from ideal, but until we get a
+ * security label in the packet itself this is the
+ * best we can do. */
+ return NF_ACCEPT;
+
+ /* standard practice, label using the parent socket */
+ sksec = sk->sk_security;
sid = sksec->sid;
} else
sid = SECINITSID_KERNEL;