From: Eric Dumazet <[email protected]>
In commit e446f9dfe17b ("net: synack packets can be attached to request
sockets"), I missed one remaining case of invalid skb->sk->sk_security
access.
Dmitry Vyukov got a KASan report pointing to it.
Add selinux_skb_sk() helper that is responsible to get back to the
listener if skb is attached to a request socket, instead of
duplicating the logic.
Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of
listener")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: Dmitry Vyukov <[email protected]>
Cc: Paul Moore <[email protected]>
---
security/selinux/hooks.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 26f4039d54b8..c9b2d5467477 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4931,11 +4931,23 @@ static unsigned int selinux_ipv4_output(void *priv,
return selinux_ip_output(skb, PF_INET);
}
+/* SYNACK messages might be attached to request sockets.
+ * To get back to sk_security, we need to look at the listener.
+ */
+static struct sock *selinux_skb_sk(const struct sk_buff *skb)
+{
+ struct sock *sk = skb->sk;
+
+ if (sk && sk->sk_state == TCP_NEW_SYN_RECV)
+ sk = inet_reqsk(sk)->rsk_listener;
+ return sk;
+}
+
static unsigned int selinux_ip_postroute_compat(struct sk_buff *skb,
int ifindex,
u16 family)
{
- struct sock *sk = skb->sk;
+ struct sock *sk = selinux_skb_sk(skb);
struct sk_security_struct *sksec;
struct common_audit_data ad;
struct lsm_network_audit net = {0,};
@@ -4990,7 +5002,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff
*skb,
if (!secmark_active && !peerlbl_active)
return NF_ACCEPT;
- sk = skb->sk;
+ sk = selinux_skb_sk(skb);
#ifdef CONFIG_XFRM
/* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec
@@ -5035,8 +5047,6 @@ static unsigned int selinux_ip_postroute(struct sk_buff
*skb,
u32 skb_sid;
struct sk_security_struct *sksec;
- if (sk->sk_state == TCP_NEW_SYN_RECV)
- sk = inet_reqsk(sk)->rsk_listener;
sksec = sk->sk_security;
if (selinux_skb_peerlbl_sid(skb, family, &skb_sid))
return NF_DROP;
--
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