Merge branch 'icmp6-drop-reason'

Eric Dumazet says:

====================
ipv6: icmp6: better drop reason support

This series aims to have more precise drop reason reports for icmp6.

This should reduce false positives on most usual cases.

This can be extended as needed later.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 94 insertions, 82 deletions

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index ef3f65d135d375..c0a3ea806cd5bf 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -76,6 +76,8 @@
 	FN(IPV6_NDISC_FRAG)		\
 	FN(IPV6_NDISC_HOP_LIMIT)	\
 	FN(IPV6_NDISC_BAD_CODE)		\
+	FN(IPV6_NDISC_BAD_OPTIONS)	\
+	FN(IPV6_NDISC_NS_OTHERHOST)	\
 	FNe(MAX)
 
 /**
@@ -330,6 +332,12 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_IPV6_NDISC_HOP_LIMIT,
 	/** @SKB_DROP_REASON_IPV6_NDISC_BAD_CODE: invalid NDISC icmp6 code. */
 	SKB_DROP_REASON_IPV6_NDISC_BAD_CODE,
+	/** @SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS: invalid NDISC options. */
+	SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS,
+	/** @SKB_DROP_REASON_IPV6_NDISC_NS_OTHERHOST: NEIGHBOUR SOLICITATION
+	 * for another host.
+	 */
+	SKB_DROP_REASON_IPV6_NDISC_NS_OTHERHOST,
 	/**
 	 * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be
 	 * used as a real 'reason'
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index f32bc98155bfb0..1f53f2a74480c0 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -705,7 +705,7 @@ int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type,
 }
 EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach);
 
-static void icmpv6_echo_reply(struct sk_buff *skb)
+static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
 	struct sock *sk;
@@ -719,18 +719,19 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 	struct dst_entry *dst;
 	struct ipcm6_cookie ipc6;
 	u32 mark = IP6_REPLY_MARK(net, skb->mark);
+	SKB_DR(reason);
 	bool acast;
 	u8 type;
 
 	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) &&
 	    net->ipv6.sysctl.icmpv6_echo_ignore_multicast)
-		return;
+		return reason;
 
 	saddr = &ipv6_hdr(skb)->daddr;
 
 	acast = ipv6_anycast_destination(skb_dst(skb), saddr);
 	if (acast && net->ipv6.sysctl.icmpv6_echo_ignore_anycast)
-		return;
+		return reason;
 
 	if (!ipv6_unicast_destination(skb) &&
 	    !(net->ipv6.sysctl.anycast_src_echo_reply && acast))
@@ -804,6 +805,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 	} else {
 		icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
 					   skb->len + sizeof(struct icmp6hdr));
+		reason = SKB_CONSUMED;
 	}
 out_dst_release:
 	dst_release(dst);
@@ -811,6 +813,7 @@ out:
 	icmpv6_xmit_unlock(sk);
 out_bh_enable:
 	local_bh_enable();
+	return reason;
 }
 
 enum skb_drop_reason icmpv6_notify(struct sk_buff *skb, u8 type,
@@ -929,12 +932,12 @@ static int icmpv6_rcv(struct sk_buff *skb)
 	switch (type) {
 	case ICMPV6_ECHO_REQUEST:
 		if (!net->ipv6.sysctl.icmpv6_echo_ignore_all)
-			icmpv6_echo_reply(skb);
+			reason = icmpv6_echo_reply(skb);
 		break;
 	case ICMPV6_EXT_ECHO_REQUEST:
 		if (!net->ipv6.sysctl.icmpv6_echo_ignore_all &&
 		    READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
-			icmpv6_echo_reply(skb);
+			reason = icmpv6_echo_reply(skb);
 		break;
 
 	case ICMPV6_ECHO_REPLY:
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 9548b5a44714f9..c4be62c99f7371 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -783,7 +783,7 @@ void ndisc_update(const struct net_device *dev, struct neighbour *neigh,
 	ndisc_ops_update(dev, neigh, flags, icmp6_type, ndopts);
 }
 
-static void ndisc_recv_ns(struct sk_buff *skb)
+static enum skb_drop_reason ndisc_recv_ns(struct sk_buff *skb)
 {
 	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
 	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
@@ -797,18 +797,17 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 	struct inet6_dev *idev = NULL;
 	struct neighbour *neigh;
 	int dad = ipv6_addr_any(saddr);
-	bool inc;
 	int is_router = -1;
+	SKB_DR(reason);
 	u64 nonce = 0;
+	bool inc;
 
-	if (skb->len < sizeof(struct nd_msg)) {
-		ND_PRINTK(2, warn, "NS: packet too short\n");
-		return;
-	}
+	if (skb->len < sizeof(struct nd_msg))
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 
 	if (ipv6_addr_is_multicast(&msg->target)) {
 		ND_PRINTK(2, warn, "NS: multicast target address\n");
-		return;
+		return reason;
 	}
 
 	/*
@@ -817,20 +816,18 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 	 */
 	if (dad && !ipv6_addr_is_solict_mult(daddr)) {
 		ND_PRINTK(2, warn, "NS: bad DAD packet (wrong destination)\n");
-		return;
+		return reason;
 	}
 
-	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {
-		ND_PRINTK(2, warn, "NS: invalid ND options\n");
-		return;
-	}
+	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts))
+		return SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS;
 
 	if (ndopts.nd_opts_src_lladdr) {
 		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr, dev);
 		if (!lladdr) {
 			ND_PRINTK(2, warn,
 				  "NS: invalid link-layer address length\n");
-			return;
+			return reason;
 		}
 
 		/* RFC2461 7.1.1:
@@ -841,7 +838,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 		if (dad) {
 			ND_PRINTK(2, warn,
 				  "NS: bad DAD packet (link-layer address option)\n");
-			return;
+			return reason;
 		}
 	}
 	if (ndopts.nd_opts_nonce && ndopts.nd_opts_nonce->nd_opt_len == 1)
@@ -869,7 +866,7 @@ have_ifp:
 				 * so fail our DAD process
 				 */
 				addrconf_dad_failure(skb, ifp);
-				return;
+				return reason;
 			} else {
 				/*
 				 * This is not a dad solicitation.
@@ -901,7 +898,7 @@ have_ifp:
 		idev = in6_dev_get(dev);
 		if (!idev) {
 			/* XXX: count this drop? */
-			return;
+			return reason;
 		}
 
 		if (ipv6_chk_acast_addr(net, dev, &msg->target) ||
@@ -924,8 +921,10 @@ have_ifp:
 					pneigh_enqueue(&nd_tbl, idev->nd_parms, n);
 				goto out;
 			}
-		} else
+		} else {
+			SKB_DR_SET(reason, IPV6_NDISC_NS_OTHERHOST);
 			goto out;
+		}
 	}
 
 	if (is_router < 0)
@@ -958,6 +957,7 @@ have_ifp:
 			      true, (ifp != NULL && inc), inc);
 		if (neigh)
 			neigh_release(neigh);
+		reason = SKB_CONSUMED;
 	}
 
 out:
@@ -965,6 +965,7 @@ out:
 		in6_ifa_put(ifp);
 	else
 		in6_dev_put(idev);
+	return reason;
 }
 
 static int accept_untracked_na(struct net_device *dev, struct in6_addr *saddr)
@@ -986,7 +987,7 @@ static int accept_untracked_na(struct net_device *dev, struct in6_addr *saddr)
 	}
 }
 
-static void ndisc_recv_na(struct sk_buff *skb)
+static enum skb_drop_reason ndisc_recv_na(struct sk_buff *skb)
 {
 	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
 	struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
@@ -999,22 +1000,21 @@ static void ndisc_recv_na(struct sk_buff *skb)
 	struct inet6_dev *idev = __in6_dev_get(dev);
 	struct inet6_ifaddr *ifp;
 	struct neighbour *neigh;
+	SKB_DR(reason);
 	u8 new_state;
 
-	if (skb->len < sizeof(struct nd_msg)) {
-		ND_PRINTK(2, warn, "NA: packet too short\n");
-		return;
-	}
+	if (skb->len < sizeof(struct nd_msg))
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 
 	if (ipv6_addr_is_multicast(&msg->target)) {
 		ND_PRINTK(2, warn, "NA: target address is multicast\n");
-		return;
+		return reason;
 	}
 
 	if (ipv6_addr_is_multicast(daddr) &&
 	    msg->icmph.icmp6_solicited) {
 		ND_PRINTK(2, warn, "NA: solicited NA is multicasted\n");
-		return;
+		return reason;
 	}
 
 	/* For some 802.11 wireless deployments (and possibly other networks),
@@ -1024,18 +1024,17 @@ static void ndisc_recv_na(struct sk_buff *skb)
 	 */
 	if (!msg->icmph.icmp6_solicited && idev &&
 	    idev->cnf.drop_unsolicited_na)
-		return;
+		return reason;
+
+	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts))
+		return SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS;
 
-	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {
-		ND_PRINTK(2, warn, "NS: invalid ND option\n");
-		return;
-	}
 	if (ndopts.nd_opts_tgt_lladdr) {
 		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_tgt_lladdr, dev);
 		if (!lladdr) {
 			ND_PRINTK(2, warn,
 				  "NA: invalid link-layer address length\n");
-			return;
+			return reason;
 		}
 	}
 	ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);
@@ -1043,7 +1042,7 @@ static void ndisc_recv_na(struct sk_buff *skb)
 		if (skb->pkt_type != PACKET_LOOPBACK
 		    && (ifp->flags & IFA_F_TENTATIVE)) {
 				addrconf_dad_failure(skb, ifp);
-				return;
+				return reason;
 		}
 		/* What should we make now? The advertisement
 		   is invalid, but ndisc specs say nothing
@@ -1059,7 +1058,7 @@ static void ndisc_recv_na(struct sk_buff *skb)
 				  "NA: %pM advertised our address %pI6c on %s!\n",
 				  eth_hdr(skb)->h_source, &ifp->addr, ifp->idev->dev->name);
 		in6_ifa_put(ifp);
-		return;
+		return reason;
 	}
 
 	neigh = neigh_lookup(&nd_tbl, &msg->target, dev);
@@ -1120,13 +1119,14 @@ static void ndisc_recv_na(struct sk_buff *skb)
 			 */
 			rt6_clean_tohost(dev_net(dev),  saddr);
 		}
-
+		reason = SKB_CONSUMED;
 out:
 		neigh_release(neigh);
 	}
+	return reason;
 }
 
-static void ndisc_recv_rs(struct sk_buff *skb)
+static enum skb_drop_reason ndisc_recv_rs(struct sk_buff *skb)
 {
 	struct rs_msg *rs_msg = (struct rs_msg *)skb_transport_header(skb);
 	unsigned long ndoptlen = skb->len - sizeof(*rs_msg);
@@ -1135,14 +1135,15 @@ static void ndisc_recv_rs(struct sk_buff *skb)
 	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
 	struct ndisc_options ndopts;
 	u8 *lladdr = NULL;
+	SKB_DR(reason);
 
 	if (skb->len < sizeof(*rs_msg))
-		return;
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 
 	idev = __in6_dev_get(skb->dev);
 	if (!idev) {
 		ND_PRINTK(1, err, "RS: can't find in6 device\n");
-		return;
+		return reason;
 	}
 
 	/* Don't accept RS if we're not in router mode */
@@ -1157,10 +1158,8 @@ static void ndisc_recv_rs(struct sk_buff *skb)
 		goto out;
 
 	/* Parse ND options */
-	if (!ndisc_parse_options(skb->dev, rs_msg->opt, ndoptlen, &ndopts)) {
-		ND_PRINTK(2, notice, "NS: invalid ND option, ignored\n");
-		goto out;
-	}
+	if (!ndisc_parse_options(skb->dev, rs_msg->opt, ndoptlen, &ndopts))
+		return SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS;
 
 	if (ndopts.nd_opts_src_lladdr) {
 		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
@@ -1177,9 +1176,10 @@ static void ndisc_recv_rs(struct sk_buff *skb)
 			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER,
 			     NDISC_ROUTER_SOLICITATION, &ndopts);
 		neigh_release(neigh);
+		reason = SKB_CONSUMED;
 	}
 out:
-	return;
+	return reason;
 }
 
 static void ndisc_ra_useropt(struct sk_buff *ra, struct nd_opt_hdr *opt)
@@ -1228,20 +1228,21 @@ errout:
 	rtnl_set_sk_err(net, RTNLGRP_ND_USEROPT, err);
 }
 
-static void ndisc_router_discovery(struct sk_buff *skb)
+static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
 {
 	struct ra_msg *ra_msg = (struct ra_msg *)skb_transport_header(skb);
+	bool send_ifinfo_notify = false;
 	struct neighbour *neigh = NULL;
-	struct inet6_dev *in6_dev;
+	struct ndisc_options ndopts;
 	struct fib6_info *rt = NULL;
+	struct inet6_dev *in6_dev;
 	u32 defrtr_usr_metric;
+	unsigned int pref = 0;
+	__u32 old_if_flags;
 	struct net *net;
+	SKB_DR(reason);
 	int lifetime;
-	struct ndisc_options ndopts;
 	int optlen;
-	unsigned int pref = 0;
-	__u32 old_if_flags;
-	bool send_ifinfo_notify = false;
 
 	__u8 *opt = (__u8 *)(ra_msg + 1);
 
@@ -1253,17 +1254,15 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		  __func__, skb->dev->name);
 	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
 		ND_PRINTK(2, warn, "RA: source address is not link-local\n");
-		return;
-	}
-	if (optlen < 0) {
-		ND_PRINTK(2, warn, "RA: packet too short\n");
-		return;
+		return reason;
 	}
+	if (optlen < 0)
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
 	if (skb->ndisc_nodetype == NDISC_NODETYPE_HOST) {
 		ND_PRINTK(2, warn, "RA: from host or unauthorized router\n");
-		return;
+		return reason;
 	}
 #endif
 
@@ -1275,13 +1274,11 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	if (!in6_dev) {
 		ND_PRINTK(0, err, "RA: can't find inet6 device for %s\n",
 			  skb->dev->name);
-		return;
+		return reason;
 	}
 
-	if (!ndisc_parse_options(skb->dev, opt, optlen, &ndopts)) {
-		ND_PRINTK(2, warn, "RA: invalid ND options\n");
-		return;
-	}
+	if (!ndisc_parse_options(skb->dev, opt, optlen, &ndopts))
+		return SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS;
 
 	if (!ipv6_accept_ra(in6_dev)) {
 		ND_PRINTK(2, info,
@@ -1362,7 +1359,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 				  "RA: %s got default router without neighbour\n",
 				  __func__);
 			fib6_info_release(rt);
-			return;
+			return reason;
 		}
 	}
 	/* Set default route metric as specified by user */
@@ -1387,7 +1384,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 			ND_PRINTK(0, err,
 				  "RA: %s failed to add default route\n",
 				  __func__);
-			return;
+			return reason;
 		}
 
 		neigh = ip6_neigh_lookup(&rt->fib6_nh->fib_nh_gw6,
@@ -1398,7 +1395,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 				  "RA: %s got default router without neighbour\n",
 				  __func__);
 			fib6_info_release(rt);
-			return;
+			return reason;
 		}
 		neigh->flags |= NTF_ROUTER;
 	} else if (rt && IPV6_EXTRACT_PREF(rt->fib6_flags) != pref) {
@@ -1485,6 +1482,7 @@ skip_linkparms:
 			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER|
 			     NEIGH_UPDATE_F_ISROUTER,
 			     NDISC_ROUTER_ADVERTISEMENT, &ndopts);
+		reason = SKB_CONSUMED;
 	}
 
 	if (!ipv6_accept_ra(in6_dev)) {
@@ -1595,15 +1593,17 @@ out:
 	fib6_info_release(rt);
 	if (neigh)
 		neigh_release(neigh);
+	return reason;
 }
 
-static void ndisc_redirect_rcv(struct sk_buff *skb)
+static enum skb_drop_reason ndisc_redirect_rcv(struct sk_buff *skb)
 {
-	u8 *hdr;
-	struct ndisc_options ndopts;
 	struct rd_msg *msg = (struct rd_msg *)skb_transport_header(skb);
 	u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
 				    offsetof(struct rd_msg, opt));
+	struct ndisc_options ndopts;
+	SKB_DR(reason);
+	u8 *hdr;
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
 	switch (skb->ndisc_nodetype) {
@@ -1611,31 +1611,31 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
 	case NDISC_NODETYPE_NODEFAULT:
 		ND_PRINTK(2, warn,
 			  "Redirect: from host or unauthorized router\n");
-		return;
+		return reason;
 	}
 #endif
 
 	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
 		ND_PRINTK(2, warn,
 			  "Redirect: source address is not link-local\n");
-		return;
+		return reason;
 	}
 
 	if (!ndisc_parse_options(skb->dev, msg->opt, ndoptlen, &ndopts))
-		return;
+		return SKB_DROP_REASON_IPV6_NDISC_BAD_OPTIONS;
 
 	if (!ndopts.nd_opts_rh) {
 		ip6_redirect_no_header(skb, dev_net(skb->dev),
 					skb->dev->ifindex);
-		return;
+		return reason;
 	}
 
 	hdr = (u8 *)ndopts.nd_opts_rh;
 	hdr += 8;
 	if (!pskb_pull(skb, hdr - skb_transport_header(skb)))
-		return;
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 
-	icmpv6_notify(skb, NDISC_REDIRECT, 0, 0);
+	return icmpv6_notify(skb, NDISC_REDIRECT, 0, 0);
 }
 
 static void ndisc_fill_redirect_hdr_option(struct sk_buff *skb,
@@ -1781,8 +1781,9 @@ release:
 
 static void pndisc_redo(struct sk_buff *skb)
 {
-	ndisc_recv_ns(skb);
-	kfree_skb(skb);
+	enum skb_drop_reason reason = ndisc_recv_ns(skb);
+
+	kfree_skb_reason(skb, reason);
 }
 
 static int ndisc_is_multicast(const void *pkey)
@@ -1834,23 +1835,23 @@ enum skb_drop_reason ndisc_rcv(struct sk_buff *skb)
 	switch (msg->icmph.icmp6_type) {
 	case NDISC_NEIGHBOUR_SOLICITATION:
 		memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
-		ndisc_recv_ns(skb);
+		reason = ndisc_recv_ns(skb);
 		break;
 
 	case NDISC_NEIGHBOUR_ADVERTISEMENT:
-		ndisc_recv_na(skb);
+		reason = ndisc_recv_na(skb);
 		break;
 
 	case NDISC_ROUTER_SOLICITATION:
-		ndisc_recv_rs(skb);
+		reason = ndisc_recv_rs(skb);
 		break;
 
 	case NDISC_ROUTER_ADVERTISEMENT:
-		ndisc_router_discovery(skb);
+		reason = ndisc_router_discovery(skb);
 		break;
 
 	case NDISC_REDIRECT:
-		ndisc_redirect_rcv(skb);
+		reason = ndisc_redirect_rcv(skb);
 		break;
 	}