ila: add checksum neutral map auto

Add checksum neutral auto that performs checksum neutral mapping
without using the C-bit. This is enabled by configuration of
a mapping.

The checksum neutral function has been split into
ila_csum_do_neutral_fmt and ila_csum_do_neutral_nofmt. The former
handles the C-bit and includes it in the adjustment value. The latter
just sets the adjustment value on the locator diff only.

Added configuration for checksum neutral map aut in ila_lwt
and ila_xlat.

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

include/uapi/linux/ila.h

···
 	ILA_CSUM_ADJUST_TRANSPORT,
 	ILA_CSUM_NEUTRAL_MAP,
 	ILA_CSUM_NO_ACTION,
+	ILA_CSUM_NEUTRAL_MAP_AUTO,
 };
 
 #endif /* _UAPI_LINUX_ILA_H */

net/ipv6/ila/ila_common.c

···
 	return get_csum_diff_iaddr(ila_a2i(&ip6h->daddr), p);
 }
 
-static void ila_csum_do_neutral(struct ila_addr *iaddr,
-				struct ila_params *p)
+static void ila_csum_do_neutral_fmt(struct ila_addr *iaddr,
+				    struct ila_params *p)
 {
 	__sum16 *adjust = (__force __sum16 *)&iaddr->ident.v16[3];
 	__wsum diff, fval;
···
 	iaddr->ident.csum_neutral ^= 1;
 }
 
+static void ila_csum_do_neutral_nofmt(struct ila_addr *iaddr,
+				      struct ila_params *p)
+{
+	__sum16 *adjust = (__force __sum16 *)&iaddr->ident.v16[3];
+	__wsum diff;
+
+	diff = get_csum_diff_iaddr(iaddr, p);
+
+	*adjust = ~csum_fold(csum_add(diff, csum_unfold(*adjust)));
+}
+
 static void ila_csum_adjust_transport(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);
+	struct ipv6hdr *ip6h = ipv6_hdr(skb);
+	__wsum diff;
 
 	switch (ip6h->nexthdr) {
 	case NEXTHDR_TCP:
···
 		}
 		break;
 	}
-
-	/* Now change destination address */
-	iaddr->loc = p->locator;
 }
 
 void ila_update_ipv6_locator(struct sk_buff *skb, struct ila_params *p,
-			     bool set_csum_neutral)
+			     bool sir2ila)
 {
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
 	struct ila_addr *iaddr = ila_a2i(&ip6h->daddr);
 
-	/* First deal with the transport checksum */
-	if (ila_csum_neutral_set(iaddr->ident)) {
-		/* C-bit is set in the locator indicating that this
-		 * is a locator being translated to a SIR address.
-		 * Perform (receiver) checksum-neutral translation.
-		 */
-		if (!set_csum_neutral)
-			ila_csum_do_neutral(iaddr, p);
-	} else {
-		switch (p->csum_mode) {
-		case ILA_CSUM_ADJUST_TRANSPORT:
-			ila_csum_adjust_transport(skb, p);
-			break;
-		case ILA_CSUM_NEUTRAL_MAP:
-			ila_csum_do_neutral(iaddr, p);
-			break;
-		case ILA_CSUM_NO_ACTION:
+	switch (p->csum_mode) {
+	case ILA_CSUM_ADJUST_TRANSPORT:
+		ila_csum_adjust_transport(skb, p);
+		break;
+	case ILA_CSUM_NEUTRAL_MAP:
+		if (sir2ila) {
+			if (WARN_ON(ila_csum_neutral_set(iaddr->ident))) {
+				/* Checksum flag should never be
+				 * set in a formatted SIR address.
+				 */
+				break;
+			}
+		} else if (!ila_csum_neutral_set(iaddr->ident)) {
+			/* ILA to SIR translation and C-bit isn't
+			 * set so we're good.
+			 */
 			break;
 		}
+		ila_csum_do_neutral_fmt(iaddr, p);
+		break;
+	case ILA_CSUM_NEUTRAL_MAP_AUTO:
+		ila_csum_do_neutral_nofmt(iaddr, p);
+		break;
+	case ILA_CSUM_NO_ACTION:
+		break;
 	}
 
 	/* Now change destination address */

net/ipv6/ila/ila_lwt.c

···
 	struct lwtunnel_state *newts;
 	const struct fib6_config *cfg6 = cfg;
 	struct ila_addr *iaddr;
+	u8 csum_mode = ILA_CSUM_NO_ACTION;
 	int ret;
 
 	if (family != AF_INET6)
···
 		return -EINVAL;
 	}
 
-	iaddr = (struct ila_addr *)&cfg6->fc_dst;
-
-	if (!ila_addr_is_ila(iaddr) || ila_csum_neutral_set(iaddr->ident)) {
-		/* Don't allow translation for a non-ILA address or checksum
-		 * neutral flag to be set.
-		 */
-		return -EINVAL;
-	}
-
 	ret = nla_parse_nested(tb, ILA_ATTR_MAX, nla, ila_nl_policy, extack);
 	if (ret < 0)
 		return ret;
 
 	if (!tb[ILA_ATTR_LOCATOR])
 		return -EINVAL;
+
+	iaddr = (struct ila_addr *)&cfg6->fc_dst;
+
+	if (tb[ILA_ATTR_CSUM_MODE])
+		csum_mode = nla_get_u8(tb[ILA_ATTR_CSUM_MODE]);
+
+	if (csum_mode == ILA_CSUM_NEUTRAL_MAP &&
+	    ila_csum_neutral_set(iaddr->ident)) {
+		/* Don't allow translation if checksum neutral bit is
+		 * configured and it's set in the SIR address.
+		 */
+		return -EINVAL;
+	}
 
 	newts = lwtunnel_state_alloc(sizeof(*ilwt));
 	if (!newts)
···
 
 	p = ila_params_lwtunnel(newts);
 
+	p->csum_mode = csum_mode;
 	p->locator.v64 = (__force __be64)nla_get_u64(tb[ILA_ATTR_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);
-
-	if (tb[ILA_ATTR_CSUM_MODE])
-		p->csum_mode = nla_get_u8(tb[ILA_ATTR_CSUM_MODE]);
 
 	ila_init_saved_csum(p);
 

net/ipv6/ila/ila_xlat.c

···
 
 	if (info->attrs[ILA_ATTR_CSUM_MODE])
 		xp->ip.csum_mode = nla_get_u8(info->attrs[ILA_ATTR_CSUM_MODE]);
+	else
+		xp->ip.csum_mode = ILA_CSUM_NO_ACTION;
 
 	if (info->attrs[ILA_ATTR_IFINDEX])
 		xp->ifindex = nla_get_s32(info->attrs[ILA_ATTR_IFINDEX]);
···
 	}
 }
 
-static int ila_xlat_addr(struct sk_buff *skb, bool set_csum_neutral);
+static int ila_xlat_addr(struct sk_buff *skb, bool sir2ila);
 
 static unsigned int
 ila_nf_input(void *priv,
···
 			      (__force u64)ila->xp.ip.locator_match.v64,
 			      ILA_ATTR_PAD) ||
 	    nla_put_s32(msg, ILA_ATTR_IFINDEX, ila->xp.ifindex) ||
-	    nla_put_u32(msg, ILA_ATTR_CSUM_MODE, ila->xp.ip.csum_mode))
+	    nla_put_u8(msg, ILA_ATTR_CSUM_MODE, ila->xp.ip.csum_mode))
 		return -1;
 
 	return 0;
···
 	.size = sizeof(struct ila_net),
 };
 
-static int ila_xlat_addr(struct sk_buff *skb, bool set_csum_neutral)
+static int ila_xlat_addr(struct sk_buff *skb, bool sir2ila)
 {
 	struct ila_map *ila;
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
···
 
 	ila = ila_lookup_wildcards(iaddr, skb->dev->ifindex, ilan);
 	if (ila)
-		ila_update_ipv6_locator(skb, &ila->xp.ip, set_csum_neutral);
+		ila_update_ipv6_locator(skb, &ila->xp.ip, sir2ila);
 
 	rcu_read_unlock();