ila: Add struct definitions and helpers

Add structures for identifiers, locators, and an ila address which
is composed of a locator and identifier and in6_addr can be cast to
it. This includes a three bit type field and enums for the types defined
in ILA I-D.

In ILA lwt don't allow user to set a translation for a non-ILA
address (type of identifier is zero meaning it is an IID). This also
requires that the destination prefix is at least 65 bytes (64
bit locator and first byte of identifier).
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ila/ila.h

@@ -23,9 +23,70 @@
 #include <net/protocol.h>
 #include <uapi/linux/ila.h>
 
+struct ila_locator {
+	union {
+		__u8            v8[8];
+		__be16          v16[4];
+		__be32          v32[2];
+		__be64		v64;
+	};
+};
+
+struct ila_identifier {
+	union {
+		struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+			u8 __space:5;
+			u8 type:3;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+			u8 type:3;
+			u8 __space:5;
+#else
+#error  "Adjust your <asm/byteorder.h> defines"
+#endif
+			u8 __space2[7];
+		};
+		__u8            v8[8];
+		__be16          v16[4];
+		__be32          v32[2];
+		__be64		v64;
+	};
+};
+
+enum {
+	ILA_ATYPE_IID = 0,
+	ILA_ATYPE_LUID,
+	ILA_ATYPE_VIRT_V4,
+	ILA_ATYPE_VIRT_UNI_V6,
+	ILA_ATYPE_VIRT_MULTI_V6,
+	ILA_ATYPE_RSVD_1,
+	ILA_ATYPE_RSVD_2,
+	ILA_ATYPE_RSVD_3,
+};
+
+struct ila_addr {
+	union {
+		struct in6_addr addr;
+		struct {
+			struct ila_locator loc;
+			struct ila_identifier ident;
+		};
+	};
+};
+
+static inline struct ila_addr *ila_a2i(struct in6_addr *addr)
+{
+	return (struct ila_addr *)addr;
+}
+
+static inline bool ila_addr_is_ila(struct ila_addr *iaddr)
+{
+	return (iaddr->ident.type != ILA_ATYPE_IID);
+}
+
 struct ila_params {
-	__be64 locator;
-	__be64 locator_match;
+	struct ila_locator locator;
+	struct ila_locator locator_match;
 	__wsum csum_diff;
 };
 
@@ -38,7 +99,7 @@ static inline __wsum compute_csum_diff8(const __be32 *from, const __be32 *to)
 	return csum_partial(diff, sizeof(diff), 0);
 }
 
-void update_ipv6_locator(struct sk_buff *skb, struct ila_params *p);
+void ila_update_ipv6_locator(struct sk_buff *skb, struct ila_params *p);
 
 int ila_lwt_init(void);
 void ila_lwt_fini(void);

net/ipv6/ila/ila_common.c

@@ -15,17 +15,20 @@
 
 static __wsum get_csum_diff(struct ipv6hdr *ip6h, struct ila_params *p)
 {
-	if (*(__be64 *)&ip6h->daddr == p->locator_match)
+	struct ila_addr *iaddr = ila_a2i(&ip6h->daddr);
+
+	if (iaddr->loc.v64 == p->locator_match.v64)
 		return p->csum_diff;
 	else
-		return compute_csum_diff8((__be32 *)&ip6h->daddr,
+		return compute_csum_diff8((__be32 *)&iaddr->loc,
 					  (__be32 *)&p->locator);
 }
 
-void update_ipv6_locator(struct sk_buff *skb, struct ila_params *p)
+void ila_update_ipv6_locator(struct sk_buff *skb, struct ila_params *p)
 {
 	__wsum diff;
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
+	struct ila_addr *iaddr = ila_a2i(&ip6h->daddr);
 	size_t nhoff = sizeof(struct ipv6hdr);
 
 	/* First update checksum */
@@ -68,7 +71,7 @@ void update_ipv6_locator(struct sk_buff *skb, struct ila_params *p)
 	}
 
 	/* Now change destination address */
-	*(__be64 *)&ip6h->daddr = p->locator;
+	iaddr->loc = p->locator;
 }
 
 static int __init ila_init(void)

net/ipv6/ila/ila_lwt.c

@@ -26,7 +26,7 @@ static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 	if (skb->protocol != htons(ETH_P_IPV6))
 		goto drop;
 
-	update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
+	ila_update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
 
 	return dst->lwtstate->orig_output(net, sk, skb);
 
@@ -42,7 +42,7 @@ static int ila_input(struct sk_buff *skb)
 	if (skb->protocol != htons(ETH_P_IPV6))
 		goto drop;
 
-	update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
+	ila_update_ipv6_locator(skb, ila_params_lwtunnel(dst->lwtstate));
 
 	return dst->lwtstate->orig_input(skb);
 
@@ -64,11 +64,26 @@ static int ila_build_state(struct net_device *dev, struct nlattr *nla,
 	size_t encap_len = sizeof(*p);
 	struct lwtunnel_state *newts;
 	const struct fib6_config *cfg6 = cfg;
+	struct ila_addr *iaddr;
 	int ret;
 
 	if (family != AF_INET6)
 		return -EINVAL;
 
+	if (cfg6->fc_dst_len < sizeof(struct ila_locator) + 1) {
+		/* Need to have full locator and at least type field
+		 * included in destination
+		 */
+		return -EINVAL;
+	}
+
+	iaddr = (struct ila_addr *)&cfg6->fc_dst;
+
+	if (!ila_addr_is_ila(iaddr)) {
+		/* Don't allow setting a translation for a non-ILA address */
+		return -EINVAL;
+	}
+
 	ret = nla_parse_nested(tb, ILA_ATTR_MAX, nla,
 			       ila_nl_policy);
 	if (ret < 0)
@@ -84,16 +99,14 @@ static int ila_build_state(struct net_device *dev, struct nlattr *nla,
 	newts->len = encap_len;
 	p = ila_params_lwtunnel(newts);
 
-	p->locator = (__force __be64)nla_get_u64(tb[ILA_ATTR_LOCATOR]);
+	p->locator.v64 = (__force __be64)nla_get_u64(tb[ILA_ATTR_LOCATOR]);
 
-	if (cfg6->fc_dst_len > sizeof(__be64)) {
-		/* Precompute checksum difference for translation since we
-		 * know both the old locator and the new one.
-		 */
-		p->locator_match = *(__be64 *)&cfg6->fc_dst;
-		p->csum_diff = compute_csum_diff8(
-			(__be32 *)&p->locator_match, (__be32 *)&p->locator);
-	}
+	/* Precompute checksum difference for translation since we
+	 * know both the old locator and the new one.
+	 */
+	p->locator_match = iaddr->loc;
+	p->csum_diff = compute_csum_diff8(
+		(__be32 *)&p->locator_match, (__be32 *)&p->locator);
 
 	newts->type = LWTUNNEL_ENCAP_ILA;
 	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
@@ -109,7 +122,7 @@ static int ila_fill_encap_info(struct sk_buff *skb,
 {
 	struct ila_params *p = ila_params_lwtunnel(lwtstate);
 
-	if (nla_put_u64_64bit(skb, ILA_ATTR_LOCATOR, (__force u64)p->locator,
+	if (nla_put_u64_64bit(skb, ILA_ATTR_LOCATOR, (__force u64)p->locator.v64,
 			      ILA_ATTR_PAD))
 		goto nla_put_failure;
 
@@ -130,7 +143,7 @@ static int ila_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 	struct ila_params *a_p = ila_params_lwtunnel(a);
 	struct ila_params *b_p = ila_params_lwtunnel(b);
 
-	return (a_p->locator != b_p->locator);
+	return (a_p->locator.v64 != b_p->locator.v64);
 }
 
 static const struct lwtunnel_encap_ops ila_encap_ops = {