Merge branch 'icmp6-support-rfc-4884'

Willem de Bruijn says:

====================
icmp6: support rfc 4884

Extend the feature merged earlier this week for IPv4 to IPv6.

I expected this to be a single patch, but patch 1 seemed better to be
stand-alone

patch 1: small fix in length calculation
patch 2: factor out ipv4-specific
patch 3: add ipv6

changes v1->v2: add missing static keyword in patch 3
====================

Signed-off-by: David S. Miller <[e-mail]>

include/linux/icmp.h

···
 }
 
 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
-			   struct sock_ee_data_rfc4884 *out);
+			   struct sock_ee_data_rfc4884 *out,
+			   int thlen, int off);
 
 #endif	/* _LINUX_ICMP_H */

include/linux/ipv6.h

···
 				autoflowlabel:1,
 				autoflowlabel_set:1,
 				mc_all:1,
+				recverr_rfc4884:1,
 				rtalert_isolate:1;
 	__u8			min_hopcount;
 	__u8			tclass;

include/uapi/linux/icmpv6.h

···
 #define icmp6_mtu		icmp6_dataun.un_data32[0]
 #define icmp6_unused		icmp6_dataun.un_data32[0]
 #define icmp6_maxdelay		icmp6_dataun.un_data16[0]
+#define icmp6_datagram_len	icmp6_dataun.un_data8[0]
 #define icmp6_router		icmp6_dataun.u_nd_advt.router
 #define icmp6_solicited		icmp6_dataun.u_nd_advt.solicited
 #define icmp6_override		icmp6_dataun.u_nd_advt.override

include/uapi/linux/in6.h

···
 #define IPV6_LEAVE_ANYCAST	28
 #define IPV6_MULTICAST_ALL	29
 #define IPV6_ROUTER_ALERT_ISOLATE	30
+#define IPV6_RECVERR_RFC4884	31
 
 /* IPV6_MTU_DISCOVER values */
 #define IPV6_PMTUDISC_DONT		0

net/ipv4/icmp.c

···
 }
 
 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
-			   struct sock_ee_data_rfc4884 *out)
+			   struct sock_ee_data_rfc4884 *out,
+			   int thlen, int off)
 {
-	int hlen, off;
+	int hlen;
 
-	switch (icmp_hdr(skb)->type) {
-	case ICMP_DEST_UNREACH:
-	case ICMP_TIME_EXCEEDED:
-	case ICMP_PARAMETERPROB:
-		break;
-	default:
-		return;
-	}
-
-	/* outer headers up to inner iph. skb->data is at inner payload */
-	hlen = -skb_transport_offset(skb) - sizeof(struct icmphdr);
-
-	/* per rfc 791: maximum packet length of 576 bytes */
-	if (hlen + skb->len > 576)
-		return;
+	/* original datagram headers: end of icmph to payload (skb->data) */
+	hlen = -skb_transport_offset(skb) - thlen;
 
 	/* per rfc 4884: minimal datagram length of 128 bytes */
-	off = icmp_hdr(skb)->un.reserved[1] * sizeof(u32);
-	if (off < 128)
+	if (off < 128 || off < hlen)
 		return;
 
 	/* kernel has stripped headers: return payload offset in bytes */
···
 	if (!ip_icmp_error_rfc4884_validate(skb, off))
 		out->flags |= SO_EE_RFC4884_FLAG_INVALID;
 }
+EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
 
 int icmp_err(struct sk_buff *skb, u32 info)
 {

net/ipv4/ip_sockglue.c

···
 	return 0;
 }
 
+static void ipv4_icmp_error_rfc4884(const struct sk_buff *skb,
+				    struct sock_ee_data_rfc4884 *out)
+{
+	switch (icmp_hdr(skb)->type) {
+	case ICMP_DEST_UNREACH:
+	case ICMP_TIME_EXCEEDED:
+	case ICMP_PARAMETERPROB:
+		ip_icmp_error_rfc4884(skb, out, sizeof(struct icmphdr),
+				      icmp_hdr(skb)->un.reserved[1] * 4);
+	}
+}
+
 void ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
 		   __be16 port, u32 info, u8 *payload)
 {
···
 
 	if (skb_pull(skb, payload - skb->data)) {
 		if (inet_sk(sk)->recverr_rfc4884)
-			ip_icmp_error_rfc4884(skb, &serr->ee.ee_rfc4884);
+			ipv4_icmp_error_rfc4884(skb, &serr->ee.ee_rfc4884);
 
 		skb_reset_transport_header(skb);
 		if (sock_queue_err_skb(sk, skb) == 0)

net/ipv6/datagram.c

···
 #include <linux/route.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/icmp.h>
 
 #include <net/ipv6.h>
 #include <net/ndisc.h>
···
 }
 EXPORT_SYMBOL_GPL(ip6_datagram_connect_v6_only);
 
+static void ipv6_icmp_error_rfc4884(const struct sk_buff *skb,
+				    struct sock_ee_data_rfc4884 *out)
+{
+	switch (icmp6_hdr(skb)->icmp6_type) {
+	case ICMPV6_TIME_EXCEED:
+	case ICMPV6_DEST_UNREACH:
+		ip_icmp_error_rfc4884(skb, out, sizeof(struct icmp6hdr),
+				      icmp6_hdr(skb)->icmp6_datagram_len * 8);
+	}
+}
+
 void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
 		     __be16 port, u32 info, u8 *payload)
 {
···
 	serr->port = port;
 
 	__skb_pull(skb, payload - skb->data);
+
+	if (inet6_sk(sk)->recverr_rfc4884)
+		ipv6_icmp_error_rfc4884(skb, &serr->ee.ee_rfc4884);
+
 	skb_reset_transport_header(skb);
 
 	if (sock_queue_err_skb(sk, skb))

net/ipv6/ipv6_sockglue.c

···
 		np->rxopt.bits.recvfragsize = valbool;
 		retv = 0;
 		break;
+	case IPV6_RECVERR_RFC4884:
+		if (optlen < sizeof(int))
+			goto e_inval;
+		if (val < 0 || val > 1)
+			goto e_inval;
+		np->recverr_rfc4884 = valbool;
+		retv = 0;
+		break;
 	}
 
 	release_sock(sk);
···
 
 	case IPV6_ROUTER_ALERT_ISOLATE:
 		val = np->rtalert_isolate;
+		break;
+
+	case IPV6_RECVERR_RFC4884:
+		val = np->recverr_rfc4884;
 		break;
 
 	default: