[SECMARK]: Add secmark support to core networking.

Add a secmark field to the skbuff structure, to allow security subsystems to
place security markings on network packets.  This is similar to the nfmark
field, except is intended for implementing security policy, rather than than
networking policy.

This patch was already acked in principle by Dave Miller.

Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 34 insertions, 1 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 23bad3b..fe2c58e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -210,6 +210,7 @@ enum {
  *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c
  *	@tc_index: Traffic control index
  *	@tc_verd: traffic control verdict
+ *	@secmark: security marking
  */
 
 struct sk_buff {
@@ -289,6 +290,9 @@ struct sk_buff {
 #ifdef CONFIG_NET_DMA
 	dma_cookie_t		dma_cookie;
 #endif
+#ifdef CONFIG_NETWORK_SECMARK
+	__u32			secmark;
+#endif
 
 
 	/* These elements must be at the end, see alloc_skb() for details.  */
@@ -1400,5 +1404,23 @@ static inline void nf_reset(struct sk_buff *skb)
 static inline void nf_reset(struct sk_buff *skb) {}
 #endif /* CONFIG_NETFILTER */
 
+#ifdef CONFIG_NETWORK_SECMARK
+static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
+{
+	to->secmark = from->secmark;
+}
+
+static inline void skb_init_secmark(struct sk_buff *skb)
+{
+	skb->secmark = 0;
+}
+#else
+static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
+{ }
+
+static inline void skb_init_secmark(struct sk_buff *skb)
+{ }
+#endif
+
 #endif	/* __KERNEL__ */
 #endif	/* _LINUX_SKBUFF_H */
diff --git a/net/Kconfig b/net/Kconfig
index ccadc8e..c6cec5a 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -66,6 +66,13 @@ source "net/ipv6/Kconfig"
 
 endif # if INET
 
+config NETWORK_SECMARK
+	bool "Security Marking"
+	help
+	  This enables security marking of network packets, similar
+	  to nfmark, but designated for security purposes.
+	  If you are unsure how to answer this question, answer N.
+
 menuconfig NETFILTER
 	bool "Network packet filtering (replaces ipchains)"
 	---help---
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index fb3770f..96cdcbe 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -464,7 +464,7 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 	n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
 	C(input_dev);
 #endif
-
+	skb_copy_secmark(n, skb);
 #endif
 	C(truesize);
 	atomic_set(&n->users, 1);
@@ -526,6 +526,7 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 #endif
 	new->tc_index	= old->tc_index;
 #endif
+	skb_copy_secmark(new, old);
 	atomic_set(&new->users, 1);
 	skb_shinfo(new)->tso_size = skb_shinfo(old)->tso_size;
 	skb_shinfo(new)->tso_segs = skb_shinfo(old)->tso_segs;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index cff9c3a..d4bb3fa 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -410,6 +410,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 	nf_bridge_get(to->nf_bridge);
 #endif
 #endif
+	skb_copy_secmark(to, from);
 }
 
 /*
diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c
index 0bba3c2..431a3ce 100644
--- a/net/ipv4/netfilter/ipt_REJECT.c
+++ b/net/ipv4/netfilter/ipt_REJECT.c
@@ -147,6 +147,7 @@ static void send_reset(struct sk_buff *oldskb, int hook)
 	/* This packet will not be the same as the other: clear nf fields */
 	nf_reset(nskb);
 	nskb->nfmark = 0;
+	skb_init_secmark(nskb);
 
 	tcph = (struct tcphdr *)((u_int32_t*)nskb->nh.iph + nskb->nh.iph->ihl);
 
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 416f6e4..d29620f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -459,6 +459,7 @@ static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 	nf_bridge_get(to->nf_bridge);
 #endif
 #endif
+	skb_copy_secmark(to, from);
 }
 
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)