// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2016 Anders K. Pedersen <akp@cohaesio.com>
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*/
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#include <linux/kernel.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/dst.h>
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#include <net/ip6_route.h>
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#include <net/route.h>
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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struct nft_rt {
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enum nft_rt_keys key:8;
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u8 dreg;
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};
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static u16 get_tcpmss(const struct nft_pktinfo *pkt, const struct dst_entry *skbdst)
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{
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u32 minlen = sizeof(struct ipv6hdr), mtu = dst_mtu(skbdst);
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const struct sk_buff *skb = pkt->skb;
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struct dst_entry *dst = NULL;
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struct flowi fl;
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memset(&fl, 0, sizeof(fl));
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switch (nft_pf(pkt)) {
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case NFPROTO_IPV4:
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fl.u.ip4.daddr = ip_hdr(skb)->saddr;
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minlen = sizeof(struct iphdr) + sizeof(struct tcphdr);
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break;
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case NFPROTO_IPV6:
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fl.u.ip6.daddr = ipv6_hdr(skb)->saddr;
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minlen = sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
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break;
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}
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nf_route(nft_net(pkt), &dst, &fl, false, nft_pf(pkt));
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if (dst) {
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mtu = min(mtu, dst_mtu(dst));
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dst_release(dst);
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}
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if (mtu <= minlen || mtu > 0xffff)
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return TCP_MSS_DEFAULT;
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return mtu - minlen;
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}
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void nft_rt_get_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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const struct nft_rt *priv = nft_expr_priv(expr);
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const struct sk_buff *skb = pkt->skb;
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u32 *dest = ®s->data[priv->dreg];
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const struct dst_entry *dst;
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dst = skb_dst(skb);
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if (!dst)
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goto err;
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switch (priv->key) {
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#ifdef CONFIG_IP_ROUTE_CLASSID
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case NFT_RT_CLASSID:
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*dest = dst->tclassid;
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break;
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#endif
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case NFT_RT_NEXTHOP4:
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if (nft_pf(pkt) != NFPROTO_IPV4)
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goto err;
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*dest = (__force u32)rt_nexthop((const struct rtable *)dst,
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ip_hdr(skb)->daddr);
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break;
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case NFT_RT_NEXTHOP6:
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if (nft_pf(pkt) != NFPROTO_IPV6)
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goto err;
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memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
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&ipv6_hdr(skb)->daddr),
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sizeof(struct in6_addr));
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break;
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case NFT_RT_TCPMSS:
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nft_reg_store16(dest, get_tcpmss(pkt, dst));
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break;
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#ifdef CONFIG_XFRM
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case NFT_RT_XFRM:
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nft_reg_store8(dest, !!dst->xfrm);
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break;
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#endif
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default:
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WARN_ON(1);
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goto err;
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}
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return;
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err:
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regs->verdict.code = NFT_BREAK;
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}
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static const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
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[NFTA_RT_DREG] = { .type = NLA_U32 },
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[NFTA_RT_KEY] = { .type = NLA_U32 },
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};
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static int nft_rt_get_init(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nlattr * const tb[])
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{
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struct nft_rt *priv = nft_expr_priv(expr);
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unsigned int len;
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if (tb[NFTA_RT_KEY] == NULL ||
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tb[NFTA_RT_DREG] == NULL)
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return -EINVAL;
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priv->key = ntohl(nla_get_be32(tb[NFTA_RT_KEY]));
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switch (priv->key) {
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#ifdef CONFIG_IP_ROUTE_CLASSID
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case NFT_RT_CLASSID:
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#endif
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case NFT_RT_NEXTHOP4:
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len = sizeof(u32);
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break;
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case NFT_RT_NEXTHOP6:
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len = sizeof(struct in6_addr);
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break;
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case NFT_RT_TCPMSS:
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len = sizeof(u16);
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break;
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#ifdef CONFIG_XFRM
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case NFT_RT_XFRM:
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len = sizeof(u8);
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break;
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#endif
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default:
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return -EOPNOTSUPP;
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}
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return nft_parse_register_store(ctx, tb[NFTA_RT_DREG], &priv->dreg,
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NULL, NFT_DATA_VALUE, len);
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}
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static int nft_rt_get_dump(struct sk_buff *skb,
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const struct nft_expr *expr)
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{
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const struct nft_rt *priv = nft_expr_priv(expr);
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if (nla_put_be32(skb, NFTA_RT_KEY, htonl(priv->key)))
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goto nla_put_failure;
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if (nft_dump_register(skb, NFTA_RT_DREG, priv->dreg))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -1;
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}
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static int nft_rt_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
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const struct nft_data **data)
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{
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const struct nft_rt *priv = nft_expr_priv(expr);
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unsigned int hooks;
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switch (priv->key) {
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case NFT_RT_NEXTHOP4:
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case NFT_RT_NEXTHOP6:
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case NFT_RT_CLASSID:
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case NFT_RT_XFRM:
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return 0;
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case NFT_RT_TCPMSS:
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hooks = (1 << NF_INET_FORWARD) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_POST_ROUTING);
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break;
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default:
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return -EINVAL;
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}
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return nft_chain_validate_hooks(ctx->chain, hooks);
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}
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static const struct nft_expr_ops nft_rt_get_ops = {
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.type = &nft_rt_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_rt)),
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.eval = nft_rt_get_eval,
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.init = nft_rt_get_init,
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.dump = nft_rt_get_dump,
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.validate = nft_rt_validate,
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};
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struct nft_expr_type nft_rt_type __read_mostly = {
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.name = "rt",
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.ops = &nft_rt_get_ops,
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.policy = nft_rt_policy,
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.maxattr = NFTA_RT_MAX,
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.owner = THIS_MODULE,
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};
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