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Date: Mon, 06 Oct 2008 15:20:15 -0400
From: Paul Moore <paul.moore@...com>
To: selinux@...ho.nsa.gov, netdev@...r.kernel.org,
linux-security-module@...r.kernel.org
Subject: [PATCH v7 05/17] selinux: Better local/forward check in
selinux_ip_postroute()
It turns out that checking to see if skb->sk is NULL is not a very good
indicator of a forwarded packet as some locally generated packets also have
skb->sk set to NULL. Fix this by not only checking the skb->sk field but also
the IP[6]CB(skb)->flags field for the IP[6]SKB_FORWARDED flag. While we are
at it, we are calling selinux_parse_skb() much earlier than we really should
resulting in potentially wasted cycles parsing packets for information we
might no use; so shuffle the code around a bit to fix this.
Signed-off-by: Paul Moore <paul.moore@...com>
Acked-by: James Morris <jmorris@...ei.org>
---
security/selinux/hooks.c | 126 ++++++++++++++++++++++++++++++----------------
1 files changed, 81 insertions(+), 45 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 223f474..b520667 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4070,20 +4070,28 @@ static int selinux_sock_rcv_skb_iptables_compat(struct sock *sk,
}
static int selinux_sock_rcv_skb_compat(struct sock *sk, struct sk_buff *skb,
- struct avc_audit_data *ad,
- u16 family, char *addrp)
+ u16 family)
{
int err;
struct sk_security_struct *sksec = sk->sk_security;
u32 peer_sid;
u32 sk_sid = sksec->sid;
+ struct avc_audit_data ad;
+ char *addrp;
+
+ AVC_AUDIT_DATA_INIT(&ad, NET);
+ ad.u.net.netif = skb->iif;
+ ad.u.net.family = family;
+ err = selinux_parse_skb(skb, &ad, &addrp, 1, NULL);
+ if (err)
+ return err;
if (selinux_compat_net)
- err = selinux_sock_rcv_skb_iptables_compat(sk, skb, ad,
+ err = selinux_sock_rcv_skb_iptables_compat(sk, skb, &ad,
family, addrp);
else
err = avc_has_perm(sk_sid, skb->secmark, SECCLASS_PACKET,
- PACKET__RECV, ad);
+ PACKET__RECV, &ad);
if (err)
return err;
@@ -4092,12 +4100,12 @@ static int selinux_sock_rcv_skb_compat(struct sock *sk, struct sk_buff *skb,
if (err)
return err;
err = avc_has_perm(sk_sid, peer_sid,
- SECCLASS_PEER, PEER__RECV, ad);
+ SECCLASS_PEER, PEER__RECV, &ad);
} else {
- err = selinux_netlbl_sock_rcv_skb(sksec, skb, family, ad);
+ err = selinux_netlbl_sock_rcv_skb(sksec, skb, family, &ad);
if (err)
return err;
- err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, ad);
+ err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, &ad);
}
return err;
@@ -4111,6 +4119,8 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
u32 sk_sid = sksec->sid;
struct avc_audit_data ad;
char *addrp;
+ u8 secmark_active;
+ u8 peerlbl_active;
if (family != PF_INET && family != PF_INET6)
return 0;
@@ -4119,6 +4129,18 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
family = PF_INET;
+ /* If any sort of compatibility mode is enabled then handoff processing
+ * to the selinux_sock_rcv_skb_compat() function to deal with the
+ * special handling. We do this in an attempt to keep this function
+ * as fast and as clean as possible. */
+ if (selinux_compat_net || !selinux_policycap_netpeer)
+ return selinux_sock_rcv_skb_compat(sk, skb, family);
+
+ secmark_active = selinux_secmark_enabled();
+ peerlbl_active = netlbl_enabled() || selinux_xfrm_enabled();
+ if (!secmark_active && !peerlbl_active)
+ return 0;
+
AVC_AUDIT_DATA_INIT(&ad, NET);
ad.u.net.netif = skb->iif;
ad.u.net.family = family;
@@ -4126,15 +4148,7 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
if (err)
return err;
- /* If any sort of compatibility mode is enabled then handoff processing
- * to the selinux_sock_rcv_skb_compat() function to deal with the
- * special handling. We do this in an attempt to keep this function
- * as fast and as clean as possible. */
- if (selinux_compat_net || !selinux_policycap_netpeer)
- return selinux_sock_rcv_skb_compat(sk, skb, &ad,
- family, addrp);
-
- if (netlbl_enabled() || selinux_xfrm_enabled()) {
+ if (peerlbl_active) {
u32 peer_sid;
err = selinux_skb_peerlbl_sid(skb, family, &peer_sid);
@@ -4148,7 +4162,7 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
PEER__RECV, &ad);
}
- if (selinux_secmark_enabled()) {
+ if (secmark_active) {
err = avc_has_perm(sk_sid, skb->secmark, SECCLASS_PACKET,
PACKET__RECV, &ad);
if (err)
@@ -4396,15 +4410,15 @@ static unsigned int selinux_ip_forward(struct sk_buff *skb, int ifindex,
if (!secmark_active && !peerlbl_active)
return NF_ACCEPT;
+ if (selinux_skb_peerlbl_sid(skb, family, &peer_sid) != 0)
+ return NF_DROP;
+
AVC_AUDIT_DATA_INIT(&ad, NET);
ad.u.net.netif = ifindex;
ad.u.net.family = family;
if (selinux_parse_skb(skb, &ad, &addrp, 1, NULL) != 0)
return NF_DROP;
- if (selinux_skb_peerlbl_sid(skb, family, &peer_sid) != 0)
- return NF_DROP;
-
if (peerlbl_active)
if (selinux_inet_sys_rcv_skb(ifindex, addrp, family,
peer_sid, &ad) != 0)
@@ -4505,30 +4519,36 @@ static int selinux_ip_postroute_iptables_compat(struct sock *sk,
static unsigned int selinux_ip_postroute_compat(struct sk_buff *skb,
int ifindex,
- struct avc_audit_data *ad,
- u16 family,
- char *addrp,
- u8 proto)
+ u16 family)
{
struct sock *sk = skb->sk;
struct sk_security_struct *sksec;
+ struct avc_audit_data ad;
+ char *addrp;
+ u8 proto;
if (sk == NULL)
return NF_ACCEPT;
sksec = sk->sk_security;
+ AVC_AUDIT_DATA_INIT(&ad, NET);
+ ad.u.net.netif = ifindex;
+ ad.u.net.family = family;
+ if (selinux_parse_skb(skb, &ad, &addrp, 0, &proto))
+ return NF_DROP;
+
if (selinux_compat_net) {
if (selinux_ip_postroute_iptables_compat(skb->sk, ifindex,
- ad, family, addrp))
+ &ad, family, addrp))
return NF_DROP;
} else {
if (avc_has_perm(sksec->sid, skb->secmark,
- SECCLASS_PACKET, PACKET__SEND, ad))
+ SECCLASS_PACKET, PACKET__SEND, &ad))
return NF_DROP;
}
if (selinux_policycap_netpeer)
- if (selinux_xfrm_postroute_last(sksec->sid, skb, ad, proto))
+ if (selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto))
return NF_DROP;
return NF_ACCEPT;
@@ -4542,23 +4562,15 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
struct sock *sk;
struct avc_audit_data ad;
char *addrp;
- u8 proto;
u8 secmark_active;
u8 peerlbl_active;
- AVC_AUDIT_DATA_INIT(&ad, NET);
- ad.u.net.netif = ifindex;
- ad.u.net.family = family;
- if (selinux_parse_skb(skb, &ad, &addrp, 0, &proto))
- return NF_DROP;
-
/* If any sort of compatibility mode is enabled then handoff processing
* to the selinux_ip_postroute_compat() function to deal with the
* special handling. We do this in an attempt to keep this function
* as fast and as clean as possible. */
if (selinux_compat_net || !selinux_policycap_netpeer)
- return selinux_ip_postroute_compat(skb, ifindex, &ad,
- family, addrp, proto);
+ return selinux_ip_postroute_compat(skb, ifindex, family);
/* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec
* packet transformation so allow the packet to pass without any checks
@@ -4574,21 +4586,45 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
if (!secmark_active && !peerlbl_active)
return NF_ACCEPT;
- /* if the packet is locally generated (skb->sk != NULL) then use the
- * socket's label as the peer label, otherwise the packet is being
- * forwarded through this system and we need to fetch the peer label
- * directly from the packet */
+ /* if the packet is being forwarded then get the peer label from the
+ * packet itself; otherwise check to see if it is from a local
+ * application or the kernel, if from an application get the peer label
+ * from the sending socket, otherwise use the kernel's sid */
sk = skb->sk;
- if (sk) {
+ if (sk == NULL) {
+ switch (family) {
+ case PF_INET:
+ if (IPCB(skb)->flags & IPSKB_FORWARDED)
+ secmark_perm = PACKET__FORWARD_OUT;
+ else
+ secmark_perm = PACKET__SEND;
+ break;
+ case PF_INET6:
+ if (IP6CB(skb)->flags & IP6SKB_FORWARDED)
+ secmark_perm = PACKET__FORWARD_OUT;
+ else
+ secmark_perm = PACKET__SEND;
+ break;
+ default:
+ return NF_DROP;
+ }
+ if (secmark_perm == PACKET__FORWARD_OUT) {
+ if (selinux_skb_peerlbl_sid(skb, family, &peer_sid))
+ return NF_DROP;
+ } else
+ peer_sid = SECINITSID_KERNEL;
+ } else {
struct sk_security_struct *sksec = sk->sk_security;
peer_sid = sksec->sid;
secmark_perm = PACKET__SEND;
- } else {
- if (selinux_skb_peerlbl_sid(skb, family, &peer_sid))
- return NF_DROP;
- secmark_perm = PACKET__FORWARD_OUT;
}
+ AVC_AUDIT_DATA_INIT(&ad, NET);
+ ad.u.net.netif = ifindex;
+ ad.u.net.family = family;
+ if (selinux_parse_skb(skb, &ad, &addrp, 0, NULL))
+ return NF_DROP;
+
if (secmark_active)
if (avc_has_perm(peer_sid, skb->secmark,
SECCLASS_PACKET, secmark_perm, &ad))
--
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