Commit 212cd089 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

selinux: fix random read in selinux_ip_postroute_compat()

In commit e446f9df ("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: ca6fb065 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 432599d7
...@@ -4931,11 +4931,23 @@ static unsigned int selinux_ipv4_output(void *priv, ...@@ -4931,11 +4931,23 @@ static unsigned int selinux_ipv4_output(void *priv,
return selinux_ip_output(skb, PF_INET); 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, static unsigned int selinux_ip_postroute_compat(struct sk_buff *skb,
int ifindex, int ifindex,
u16 family) u16 family)
{ {
struct sock *sk = skb->sk; struct sock *sk = selinux_skb_sk(skb);
struct sk_security_struct *sksec; struct sk_security_struct *sksec;
struct common_audit_data ad; struct common_audit_data ad;
struct lsm_network_audit net = {0,}; struct lsm_network_audit net = {0,};
...@@ -4990,7 +5002,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, ...@@ -4990,7 +5002,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb,
if (!secmark_active && !peerlbl_active) if (!secmark_active && !peerlbl_active)
return NF_ACCEPT; return NF_ACCEPT;
sk = skb->sk; sk = selinux_skb_sk(skb);
#ifdef CONFIG_XFRM #ifdef CONFIG_XFRM
/* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec /* 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, ...@@ -5035,8 +5047,6 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb,
u32 skb_sid; u32 skb_sid;
struct sk_security_struct *sksec; struct sk_security_struct *sksec;
if (sk->sk_state == TCP_NEW_SYN_RECV)
sk = inet_reqsk(sk)->rsk_listener;
sksec = sk->sk_security; sksec = sk->sk_security;
if (selinux_skb_peerlbl_sid(skb, family, &skb_sid)) if (selinux_skb_peerlbl_sid(skb, family, &skb_sid))
return NF_DROP; return NF_DROP;
......
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