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https://github.com/torvalds/linux
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netfilter: nft_exthdr: add TCP option matching
This patch implements the kernel side of the TCP option patch. Signed-off-by: Manuel Messner <mm@skelett.io> Reviewed-by: Florian Westphal <fw@strlen.de> Acked-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ -709,13 +709,27 @@ enum nft_exthdr_flags {
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};
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/**
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* enum nft_exthdr_attributes - nf_tables IPv6 extension header expression netlink attributes
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* enum nft_exthdr_op - nf_tables match options
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*
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* @NFT_EXTHDR_OP_IPV6: match against ipv6 extension headers
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* @NFT_EXTHDR_OP_TCP: match against tcp options
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*/
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enum nft_exthdr_op {
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NFT_EXTHDR_OP_IPV6,
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NFT_EXTHDR_OP_TCPOPT,
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__NFT_EXTHDR_OP_MAX
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};
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#define NFT_EXTHDR_OP_MAX (__NFT_EXTHDR_OP_MAX - 1)
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/**
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* enum nft_exthdr_attributes - nf_tables extension header expression netlink attributes
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*
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* @NFTA_EXTHDR_DREG: destination register (NLA_U32: nft_registers)
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* @NFTA_EXTHDR_TYPE: extension header type (NLA_U8)
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* @NFTA_EXTHDR_OFFSET: extension header offset (NLA_U32)
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* @NFTA_EXTHDR_LEN: extension header length (NLA_U32)
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* @NFTA_EXTHDR_FLAGS: extension header flags (NLA_U32)
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* @NFTA_EXTHDR_OP: option match type (NLA_U8)
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*/
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enum nft_exthdr_attributes {
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NFTA_EXTHDR_UNSPEC,
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@ -724,6 +738,7 @@ enum nft_exthdr_attributes {
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NFTA_EXTHDR_OFFSET,
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NFTA_EXTHDR_LEN,
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NFTA_EXTHDR_FLAGS,
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NFTA_EXTHDR_OP,
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__NFTA_EXTHDR_MAX
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};
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#define NFTA_EXTHDR_MAX (__NFTA_EXTHDR_MAX - 1)
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@ -467,10 +467,10 @@ config NF_TABLES_NETDEV
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This option enables support for the "netdev" table.
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config NFT_EXTHDR
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tristate "Netfilter nf_tables IPv6 exthdr module"
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tristate "Netfilter nf_tables exthdr module"
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help
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This option adds the "exthdr" expression that you can use to match
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IPv6 extension headers.
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IPv6 extension headers and tcp options.
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config NFT_META
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tristate "Netfilter nf_tables meta module"
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@ -15,18 +15,27 @@
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables.h>
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// FIXME:
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#include <net/ipv6.h>
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#include <net/tcp.h>
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struct nft_exthdr {
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u8 type;
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u8 offset;
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u8 len;
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u8 op;
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enum nft_registers dreg:8;
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u8 flags;
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};
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static void nft_exthdr_eval(const struct nft_expr *expr,
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static unsigned int optlen(const u8 *opt, unsigned int offset)
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{
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/* Beware zero-length options: make finite progress */
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if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0)
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return 1;
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else
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return opt[offset + 1];
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}
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static void nft_exthdr_ipv6_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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@ -52,6 +61,53 @@ static void nft_exthdr_eval(const struct nft_expr *expr,
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regs->verdict.code = NFT_BREAK;
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}
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static void nft_exthdr_tcp_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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u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
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struct nft_exthdr *priv = nft_expr_priv(expr);
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unsigned int i, optl, tcphdr_len, offset;
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u32 *dest = ®s->data[priv->dreg];
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struct tcphdr *tcph;
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u8 *opt;
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if (!pkt->tprot_set || pkt->tprot != IPPROTO_TCP)
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goto err;
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tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buff);
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if (!tcph)
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goto err;
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tcphdr_len = __tcp_hdrlen(tcph);
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if (tcphdr_len < sizeof(*tcph))
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goto err;
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tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, tcphdr_len, buff);
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if (!tcph)
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goto err;
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opt = (u8 *)tcph;
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for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
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optl = optlen(opt, i);
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if (priv->type != opt[i])
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continue;
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if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
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goto err;
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offset = i + priv->offset;
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dest[priv->len / NFT_REG32_SIZE] = 0;
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memcpy(dest, opt + offset, priv->len);
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return;
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}
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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_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
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[NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
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[NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
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@ -65,13 +121,13 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
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const struct nlattr * const tb[])
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{
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struct nft_exthdr *priv = nft_expr_priv(expr);
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u32 offset, len, flags = 0;
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u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
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int err;
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if (tb[NFTA_EXTHDR_DREG] == NULL ||
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tb[NFTA_EXTHDR_TYPE] == NULL ||
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tb[NFTA_EXTHDR_OFFSET] == NULL ||
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tb[NFTA_EXTHDR_LEN] == NULL)
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if (!tb[NFTA_EXTHDR_DREG] ||
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!tb[NFTA_EXTHDR_TYPE] ||
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!tb[NFTA_EXTHDR_OFFSET] ||
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!tb[NFTA_EXTHDR_LEN])
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return -EINVAL;
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err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
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@ -91,11 +147,18 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
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return -EINVAL;
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}
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if (tb[NFTA_EXTHDR_OP]) {
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err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
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if (err < 0)
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return err;
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}
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priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
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priv->offset = offset;
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priv->len = len;
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priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
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priv->flags = flags;
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priv->op = op;
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return nft_validate_register_store(ctx, priv->dreg, NULL,
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NFT_DATA_VALUE, priv->len);
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@ -115,6 +178,8 @@ static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
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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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@ -122,17 +187,45 @@ static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
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}
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static struct nft_expr_type nft_exthdr_type;
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static const struct nft_expr_ops nft_exthdr_ops = {
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static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
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.type = &nft_exthdr_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
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.eval = nft_exthdr_eval,
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.eval = nft_exthdr_ipv6_eval,
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.init = nft_exthdr_init,
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.dump = nft_exthdr_dump,
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};
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static const struct nft_expr_ops nft_exthdr_tcp_ops = {
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.type = &nft_exthdr_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
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.eval = nft_exthdr_tcp_eval,
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.init = nft_exthdr_init,
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.dump = nft_exthdr_dump,
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};
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static const struct nft_expr_ops *
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nft_exthdr_select_ops(const struct nft_ctx *ctx,
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const struct nlattr * const tb[])
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{
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u32 op;
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if (!tb[NFTA_EXTHDR_OP])
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return &nft_exthdr_ipv6_ops;
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op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP]));
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switch (op) {
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case NFT_EXTHDR_OP_TCPOPT:
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return &nft_exthdr_tcp_ops;
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case NFT_EXTHDR_OP_IPV6:
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return &nft_exthdr_ipv6_ops;
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}
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return ERR_PTR(-EOPNOTSUPP);
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}
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static struct nft_expr_type nft_exthdr_type __read_mostly = {
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.name = "exthdr",
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.ops = &nft_exthdr_ops,
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.select_ops = &nft_exthdr_select_ops,
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.policy = nft_exthdr_policy,
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.maxattr = NFTA_EXTHDR_MAX,
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.owner = THIS_MODULE,
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