ICMPv6: treat dest unreachable codes 5 and 6 as EACCES, not EPROTO

RFC 4443 has defined two additional codes for ICMPv6 type 1 (destination
unreachable) messages:
5 - Source address failed ingress/egress policy
6 - Reject route to destination

Now they are treated as protocol error and icmpv6_err_convert() converts them
to EPROTO.

RFC 4443 says:
"Codes 5 and 6 are more informative subsets of code 1."

Treat codes 5 and 6 as code 1 (EACCES)

Btw, connect() returning -EPROTO confuses firefox, so that fallback to
other/IPv4 addresses does not work:
https://bugzilla.mozilla.org/show_bug.cgi?id=910773

Signed-off-by: Jiri Bohac <[e-mail]>
Acked-by: Hannes Frederic Sowa <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/icmpv6.h

···
 #define ICMPV6_NOT_NEIGHBOUR		2
 #define ICMPV6_ADDR_UNREACH		3
 #define ICMPV6_PORT_UNREACH		4
+#define ICMPV6_POLICY_FAIL		5
+#define ICMPV6_REJECT_ROUTE		6
 
 /*
  *	Codes for Time Exceeded

net/ipv6/icmp.c

···
 		.err	= ECONNREFUSED,
 		.fatal	= 1,
 	},
+	{	/* POLICY_FAIL */
+		.err	= EACCES,
+		.fatal	= 1,
+	},
+	{	/* REJECT_ROUTE	*/
+		.err	= EACCES,
+		.fatal	= 1,
+	},
 };
 
 int icmpv6_err_convert(u8 type, u8 code, int *err)
···
 	switch (type) {
 	case ICMPV6_DEST_UNREACH:
 		fatal = 1;
-		if (code <= ICMPV6_PORT_UNREACH) {
+		if (code < ARRAY_SIZE(tab_unreach)) {
 			*err  = tab_unreach[code].err;
 			fatal = tab_unreach[code].fatal;
 		}