Subject: ipv6: allow rejecting with "source address failed policy"
From: Jonas Gorski <[email-masked]>

RFC6204 L-14 requires rejecting traffic from invalid addresses with
ICMPv6 Destination Unreachable, Code 5 (Source address failed ingress/
egress policy) on the LAN side, so add an appropriate rule for that.

Signed-off-by: Jonas Gorski <[email-masked]>
---
 include/net/netns/ipv6.h       |  1 +
 include/uapi/linux/fib_rules.h |  4 +++
 include/uapi/linux/rtnetlink.h |  1 +
 net/ipv4/fib_semantics.c       |  4 +++
 net/ipv4/fib_trie.c            |  1 +
 net/ipv4/ipmr.c                |  1 +
 net/ipv6/fib6_rules.c          |  4 +++
 net/ipv6/ip6mr.c               |  2 ++
 net/ipv6/route.c               | 58 +++++++++++++++++++++++++++++++++++++++++-
 9 files changed, 75 insertions(+), 1 deletion(-)

--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -88,6 +88,7 @@ struct netns_ipv6 {
 	unsigned int		fib6_routes_require_src;
 #endif
 	struct rt6_info         *ip6_prohibit_entry;
+	struct rt6_info		*ip6_policy_failed_entry;
 	struct rt6_info         *ip6_blk_hole_entry;
 	struct fib6_table       *fib6_local_tbl;
 	struct fib_rules_ops    *fib6_rules_ops;
--- a/include/uapi/linux/fib_rules.h
+++ b/include/uapi/linux/fib_rules.h
@@ -82,6 +82,10 @@ enum {
 	FR_ACT_BLACKHOLE,	/* Drop without notification */
 	FR_ACT_UNREACHABLE,	/* Drop with ENETUNREACH */
 	FR_ACT_PROHIBIT,	/* Drop with EACCES */
+	FR_ACT_RES9,
+	FR_ACT_RES10,
+	FR_ACT_RES11,
+	FR_ACT_POLICY_FAILED,	/* Drop with EACCES */
 	__FR_ACT_MAX,
 };
 
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -249,6 +249,7 @@ enum {
 	RTN_THROW,		/* Not in this table		*/
 	RTN_NAT,		/* Translate this address	*/
 	RTN_XRESOLVE,		/* Use external resolver	*/
+	RTN_POLICY_FAILED,	/* Failed ingress/egress policy */
 	__RTN_MAX
 };
 
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -143,6 +143,10 @@ const struct fib_prop fib_props[RTN_MAX
 		.error	= -EINVAL,
 		.scope	= RT_SCOPE_NOWHERE,
 	},
+	[RTN_POLICY_FAILED] = {
+		.error	= -EACCES,
+		.scope	= RT_SCOPE_UNIVERSE,
+	},
 };
 
 static void rt_fibinfo_free(struct rtable __rcu **rtp)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2741,6 +2741,7 @@ static const char *const rtn_type_names[
 	[RTN_THROW] = "THROW",
 	[RTN_NAT] = "NAT",
 	[RTN_XRESOLVE] = "XRESOLVE",
+	[RTN_POLICY_FAILED] = "POLICY_FAILED",
 };
 
 static inline const char *rtn_type(char *buf, size_t len, unsigned int t)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -175,6 +175,7 @@ static int ipmr_rule_action(struct fib_r
 	case FR_ACT_UNREACHABLE:
 		return -ENETUNREACH;
 	case FR_ACT_PROHIBIT:
+	case FR_ACT_POLICY_FAILED:
 		return -EACCES;
 	case FR_ACT_BLACKHOLE:
 	default:
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -220,6 +220,10 @@ static int __fib6_rule_action(struct fib
 		err = -EACCES;
 		rt = net->ipv6.ip6_prohibit_entry;
 		goto discard_pkt;
+	case FR_ACT_POLICY_FAILED:
+		err = -EACCES;
+		rt = net->ipv6.ip6_policy_failed_entry;
+		goto discard_pkt;
 	}
 
 	tb_id = fib_rule_get_table(rule, arg);
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -163,6 +163,8 @@ static int ip6mr_rule_action(struct fib_
 		return -ENETUNREACH;
 	case FR_ACT_PROHIBIT:
 		return -EACCES;
+	case FR_ACT_POLICY_FAILED:
+		return -EACCES;
 	case FR_ACT_BLACKHOLE:
 	default:
 		return -EINVAL;
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -96,6 +96,8 @@ static int		ip6_pkt_discard(struct sk_bu
 static int		ip6_pkt_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 static int		ip6_pkt_prohibit(struct sk_buff *skb);
 static int		ip6_pkt_prohibit_out(struct net *net, struct sock *sk, struct sk_buff *skb);
+static int		ip6_pkt_policy_failed(struct sk_buff *skb);
+static int		ip6_pkt_policy_failed_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 static void		ip6_link_failure(struct sk_buff *skb);
 static void		ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 					   struct sk_buff *skb, u32 mtu,
@@ -311,6 +313,18 @@ static const struct rt6_info ip6_prohibi
 	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
 };
 
+static const struct rt6_info ip6_policy_failed_entry_template = {
+	.dst = {
+		.__refcnt	= ATOMIC_INIT(1),
+		.__use		= 1,
+		.obsolete	= DST_OBSOLETE_FORCE_CHK,
+		.error		= -EACCES,
+		.input		= ip6_pkt_policy_failed,
+		.output		= ip6_pkt_policy_failed_out,
+	},
+	.rt6i_flags	= (RTF_REJECT | RTF_NONEXTHOP),
+};
+
 static const struct rt6_info ip6_blk_hole_entry_template = {
 	.dst = {
 		.__refcnt	= ATOMIC_INIT(1),
@@ -1034,6 +1048,7 @@ static const int fib6_prop[RTN_MAX + 1]
 	[RTN_BLACKHOLE]	= -EINVAL,
 	[RTN_UNREACHABLE] = -EHOSTUNREACH,
 	[RTN_PROHIBIT]	= -EACCES,
+	[RTN_POLICY_FAILED] = -EACCES,
 	[RTN_THROW]	= -EAGAIN,
 	[RTN_NAT]	= -EINVAL,
 	[RTN_XRESOLVE]	= -EINVAL,
@@ -1069,6 +1084,10 @@ static void ip6_rt_init_dst_reject(struc
 		rt->dst.output = ip6_pkt_prohibit_out;
 		rt->dst.input = ip6_pkt_prohibit;
 		break;
+	case RTN_POLICY_FAILED:
+		rt->dst.output = ip6_pkt_policy_failed_out;
+		rt->dst.input = ip6_pkt_policy_failed;
+		break;
 	case RTN_THROW:
 	case RTN_UNREACHABLE:
 	default:
@@ -4453,6 +4472,17 @@ static int ip6_pkt_prohibit_out(struct n
 	return ip6_pkt_drop(skb, ICMPV6_ADM_PROHIBITED, IPSTATS_MIB_OUTNOROUTES);
 }
 
+static int ip6_pkt_policy_failed(struct sk_buff *skb)
+{
+	return ip6_pkt_drop(skb, ICMPV6_POLICY_FAIL, IPSTATS_MIB_INNOROUTES);
+}
+
+static int ip6_pkt_policy_failed_out(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	skb->dev = skb_dst(skb)->dev;
+	return ip6_pkt_drop(skb, ICMPV6_POLICY_FAIL, IPSTATS_MIB_OUTNOROUTES);
+}
+
 /*
  *	Allocate a dst for local (unicast / anycast) address.
  */
@@ -4940,7 +4970,8 @@ static int rtm_to_fib6_config(struct sk_
 	if (rtm->rtm_type == RTN_UNREACHABLE ||
 	    rtm->rtm_type == RTN_BLACKHOLE ||
 	    rtm->rtm_type == RTN_PROHIBIT ||
-	    rtm->rtm_type == RTN_THROW)
+	    rtm->rtm_type == RTN_THROW ||
+	    rtm->rtm_type == RTN_POLICY_FAILED)
 		cfg->fc_flags |= RTF_REJECT;
 
 	if (rtm->rtm_type == RTN_LOCAL)
@@ -6133,6 +6164,8 @@ static int ip6_route_dev_notify(struct n
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 		net->ipv6.ip6_prohibit_entry->dst.dev = dev;
 		net->ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(dev);
+		net->ipv6.ip6_policy_failed_entry->dst.dev = dev;
+		net->ipv6.ip6_policy_failed_entry->rt6i_idev = in6_dev_get(dev);
 		net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
 		net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
 #endif
@@ -6144,6 +6177,7 @@ static int ip6_route_dev_notify(struct n
 		in6_dev_put_clear(&net->ipv6.ip6_null_entry->rt6i_idev);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 		in6_dev_put_clear(&net->ipv6.ip6_prohibit_entry->rt6i_idev);
+		in6_dev_put_clear(&net->ipv6.ip6_policy_failed_entry->rt6i_idev);
 		in6_dev_put_clear(&net->ipv6.ip6_blk_hole_entry->rt6i_idev);
 #endif
 	}
@@ -6335,6 +6369,8 @@ static int __net_init ip6_route_net_init
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	net->ipv6.fib6_has_custom_rules = false;
+
+
 	net->ipv6.ip6_prohibit_entry = kmemdup(&ip6_prohibit_entry_template,
 					       sizeof(*net->ipv6.ip6_prohibit_entry),
 					       GFP_KERNEL);
@@ -6345,11 +6381,21 @@ static int __net_init ip6_route_net_init
 			 ip6_template_metrics, true);
 	INIT_LIST_HEAD(&net->ipv6.ip6_prohibit_entry->rt6i_uncached);
 
+	net->ipv6.ip6_policy_failed_entry =
+				kmemdup(&ip6_policy_failed_entry_template,
+				sizeof(*net->ipv6.ip6_policy_failed_entry), GFP_KERNEL);
+	if (!net->ipv6.ip6_policy_failed_entry)
+		goto out_ip6_prohibit_entry;
+	net->ipv6.ip6_policy_failed_entry->dst.ops = &net->ipv6.ip6_dst_ops;
+	dst_init_metrics(&net->ipv6.ip6_policy_failed_entry->dst,
+			 ip6_template_metrics, true);
+	INIT_LIST_HEAD(&net->ipv6.ip6_policy_failed_entry->rt6i_uncached);
+
 	net->ipv6.ip6_blk_hole_entry = kmemdup(&ip6_blk_hole_entry_template,
 					       sizeof(*net->ipv6.ip6_blk_hole_entry),
 					       GFP_KERNEL);
 	if (!net->ipv6.ip6_blk_hole_entry)
-		goto out_ip6_prohibit_entry;
+		goto out_ip6_policy_failed_entry;
 	net->ipv6.ip6_blk_hole_entry->dst.ops = &net->ipv6.ip6_dst_ops;
 	dst_init_metrics(&net->ipv6.ip6_blk_hole_entry->dst,
 			 ip6_template_metrics, true);
@@ -6376,6 +6422,8 @@ out:
 	return ret;
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
+out_ip6_policy_failed_entry:
+	kfree(net->ipv6.ip6_policy_failed_entry);
 out_ip6_prohibit_entry:
 	kfree(net->ipv6.ip6_prohibit_entry);
 out_ip6_null_entry:
@@ -6395,6 +6443,7 @@ static void __net_exit ip6_route_net_exi
 	kfree(net->ipv6.ip6_null_entry);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 	kfree(net->ipv6.ip6_prohibit_entry);
+	kfree(net->ipv6.ip6_policy_failed_entry);
 	kfree(net->ipv6.ip6_blk_hole_entry);
 #endif
 	dst_entries_destroy(&net->ipv6.ip6_dst_ops);
@@ -6478,6 +6527,9 @@ void __init ip6_route_init_special_entri
 	init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
 	init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
 	init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+	init_net.ipv6.ip6_policy_failed_entry->dst.dev = init_net.loopback_dev;
+	init_net.ipv6.ip6_policy_failed_entry->rt6i_idev =
+		in6_dev_get(init_net.loopback_dev);
   #endif
 }