/*
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* Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
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* Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Development of this code funded by Astaro AG (http://www.astaro.com/)
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*/
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#include <linux/kernel.h>
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#include <linux/if_vlan.h>
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#include <linux/init.h>
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#include <linux/module.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/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_tables.h>
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/* For layer 4 checksum field offset. */
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <linux/icmpv6.h>
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/* add vlan header into the user buffer for if tag was removed by offloads */
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static bool
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nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
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{
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int mac_off = skb_mac_header(skb) - skb->data;
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u8 vlan_len, *vlanh, *dst_u8 = (u8 *) d;
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struct vlan_ethhdr veth;
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vlanh = (u8 *) &veth;
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if (offset < ETH_HLEN) {
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u8 ethlen = min_t(u8, len, ETH_HLEN - offset);
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if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
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return false;
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veth.h_vlan_proto = skb->vlan_proto;
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memcpy(dst_u8, vlanh + offset, ethlen);
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len -= ethlen;
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if (len == 0)
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return true;
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dst_u8 += ethlen;
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offset = ETH_HLEN;
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} else if (offset >= VLAN_ETH_HLEN) {
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offset -= VLAN_HLEN;
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goto skip;
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}
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veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
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veth.h_vlan_encapsulated_proto = skb->protocol;
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vlanh += offset;
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vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
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memcpy(dst_u8, vlanh, vlan_len);
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len -= vlan_len;
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if (!len)
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return true;
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dst_u8 += vlan_len;
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skip:
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return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
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}
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static void nft_payload_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_payload *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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int offset;
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if (priv->len % NFT_REG32_SIZE)
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dest[priv->len / NFT_REG32_SIZE] = 0;
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switch (priv->base) {
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case NFT_PAYLOAD_LL_HEADER:
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if (!skb_mac_header_was_set(skb))
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goto err;
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if (skb_vlan_tag_present(skb)) {
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if (!nft_payload_copy_vlan(dest, skb,
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priv->offset, priv->len))
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goto err;
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return;
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}
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offset = skb_mac_header(skb) - skb->data;
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break;
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case NFT_PAYLOAD_NETWORK_HEADER:
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offset = skb_network_offset(skb);
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break;
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case NFT_PAYLOAD_TRANSPORT_HEADER:
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if (!pkt->tprot_set)
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goto err;
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offset = pkt->xt.thoff;
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break;
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default:
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BUG();
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}
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offset += priv->offset;
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if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
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goto err;
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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_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
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[NFTA_PAYLOAD_SREG] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_DREG] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_BASE] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_LEN] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_CSUM_TYPE] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_CSUM_OFFSET] = { .type = NLA_U32 },
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[NFTA_PAYLOAD_CSUM_FLAGS] = { .type = NLA_U32 },
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};
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static int nft_payload_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_payload *priv = nft_expr_priv(expr);
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priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
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priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
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priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
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priv->dreg = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);
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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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}
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static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_payload *priv = nft_expr_priv(expr);
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if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
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nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
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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 const struct nft_expr_ops nft_payload_ops = {
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.type = &nft_payload_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
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.eval = nft_payload_eval,
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.init = nft_payload_init,
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.dump = nft_payload_dump,
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};
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const struct nft_expr_ops nft_payload_fast_ops = {
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.type = &nft_payload_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
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.eval = nft_payload_eval,
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.init = nft_payload_init,
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.dump = nft_payload_dump,
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};
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static inline void nft_csum_replace(__sum16 *sum, __wsum fsum, __wsum tsum)
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{
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*sum = csum_fold(csum_add(csum_sub(~csum_unfold(*sum), fsum), tsum));
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if (*sum == 0)
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*sum = CSUM_MANGLED_0;
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}
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static bool nft_payload_udp_checksum(struct sk_buff *skb, unsigned int thoff)
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{
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struct udphdr *uh, _uh;
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uh = skb_header_pointer(skb, thoff, sizeof(_uh), &_uh);
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if (!uh)
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return false;
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return (__force bool)uh->check;
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}
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static int nft_payload_l4csum_offset(const struct nft_pktinfo *pkt,
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struct sk_buff *skb,
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unsigned int *l4csum_offset)
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{
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if (pkt->xt.fragoff)
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return -1;
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switch (pkt->tprot) {
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case IPPROTO_TCP:
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*l4csum_offset = offsetof(struct tcphdr, check);
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break;
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case IPPROTO_UDP:
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if (!nft_payload_udp_checksum(skb, pkt->xt.thoff))
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return -1;
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/* Fall through. */
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case IPPROTO_UDPLITE:
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*l4csum_offset = offsetof(struct udphdr, check);
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break;
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case IPPROTO_ICMPV6:
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*l4csum_offset = offsetof(struct icmp6hdr, icmp6_cksum);
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break;
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default:
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return -1;
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}
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*l4csum_offset += pkt->xt.thoff;
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return 0;
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}
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static int nft_payload_l4csum_update(const struct nft_pktinfo *pkt,
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struct sk_buff *skb,
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__wsum fsum, __wsum tsum)
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{
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int l4csum_offset;
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__sum16 sum;
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/* If we cannot determine layer 4 checksum offset or this packet doesn't
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* require layer 4 checksum recalculation, skip this packet.
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*/
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if (nft_payload_l4csum_offset(pkt, skb, &l4csum_offset) < 0)
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return 0;
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if (skb_copy_bits(skb, l4csum_offset, &sum, sizeof(sum)) < 0)
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return -1;
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/* Checksum mangling for an arbitrary amount of bytes, based on
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* inet_proto_csum_replace*() functions.
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*/
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if (skb->ip_summed != CHECKSUM_PARTIAL) {
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nft_csum_replace(&sum, fsum, tsum);
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if (skb->ip_summed == CHECKSUM_COMPLETE) {
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skb->csum = ~csum_add(csum_sub(~(skb->csum), fsum),
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tsum);
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}
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} else {
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sum = ~csum_fold(csum_add(csum_sub(csum_unfold(sum), fsum),
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tsum));
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}
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if (!skb_make_writable(skb, l4csum_offset + sizeof(sum)) ||
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skb_store_bits(skb, l4csum_offset, &sum, sizeof(sum)) < 0)
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return -1;
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return 0;
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}
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static int nft_payload_csum_inet(struct sk_buff *skb, const u32 *src,
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__wsum fsum, __wsum tsum, int csum_offset)
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{
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__sum16 sum;
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if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
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return -1;
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nft_csum_replace(&sum, fsum, tsum);
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if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
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skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
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return -1;
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return 0;
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}
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static void nft_payload_set_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_payload_set *priv = nft_expr_priv(expr);
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struct sk_buff *skb = pkt->skb;
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const u32 *src = ®s->data[priv->sreg];
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int offset, csum_offset;
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__wsum fsum, tsum;
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switch (priv->base) {
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case NFT_PAYLOAD_LL_HEADER:
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if (!skb_mac_header_was_set(skb))
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goto err;
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offset = skb_mac_header(skb) - skb->data;
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break;
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case NFT_PAYLOAD_NETWORK_HEADER:
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offset = skb_network_offset(skb);
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break;
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case NFT_PAYLOAD_TRANSPORT_HEADER:
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if (!pkt->tprot_set)
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goto err;
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offset = pkt->xt.thoff;
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break;
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default:
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BUG();
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}
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csum_offset = offset + priv->csum_offset;
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offset += priv->offset;
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if ((priv->csum_type == NFT_PAYLOAD_CSUM_INET || priv->csum_flags) &&
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(priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
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skb->ip_summed != CHECKSUM_PARTIAL)) {
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fsum = skb_checksum(skb, offset, priv->len, 0);
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tsum = csum_partial(src, priv->len, 0);
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if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
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nft_payload_csum_inet(skb, src, fsum, tsum, csum_offset))
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goto err;
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if (priv->csum_flags &&
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nft_payload_l4csum_update(pkt, skb, fsum, tsum) < 0)
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goto err;
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}
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if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
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skb_store_bits(skb, offset, src, priv->len) < 0)
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goto err;
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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 int nft_payload_set_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_payload_set *priv = nft_expr_priv(expr);
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priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
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priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
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priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
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priv->sreg = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);
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if (tb[NFTA_PAYLOAD_CSUM_TYPE])
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priv->csum_type =
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ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
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if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
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priv->csum_offset =
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ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));
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if (tb[NFTA_PAYLOAD_CSUM_FLAGS]) {
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u32 flags;
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flags = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_FLAGS]));
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if (flags & ~NFT_PAYLOAD_L4CSUM_PSEUDOHDR)
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return -EINVAL;
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priv->csum_flags = flags;
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}
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switch (priv->csum_type) {
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case NFT_PAYLOAD_CSUM_NONE:
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case NFT_PAYLOAD_CSUM_INET:
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break;
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default:
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return -EOPNOTSUPP;
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}
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return nft_validate_register_load(priv->sreg, priv->len);
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}
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static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_payload_set *priv = nft_expr_priv(expr);
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if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
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nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
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htonl(priv->csum_offset)) ||
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nla_put_be32(skb, NFTA_PAYLOAD_CSUM_FLAGS, htonl(priv->csum_flags)))
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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 const struct nft_expr_ops nft_payload_set_ops = {
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.type = &nft_payload_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
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.eval = nft_payload_set_eval,
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.init = nft_payload_set_init,
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.dump = nft_payload_set_dump,
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};
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static const struct nft_expr_ops *
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nft_payload_select_ops(const struct nft_ctx *ctx,
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const struct nlattr * const tb[])
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{
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enum nft_payload_bases base;
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unsigned int offset, len;
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if (tb[NFTA_PAYLOAD_BASE] == NULL ||
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tb[NFTA_PAYLOAD_OFFSET] == NULL ||
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tb[NFTA_PAYLOAD_LEN] == NULL)
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return ERR_PTR(-EINVAL);
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base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
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switch (base) {
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case NFT_PAYLOAD_LL_HEADER:
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case NFT_PAYLOAD_NETWORK_HEADER:
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case NFT_PAYLOAD_TRANSPORT_HEADER:
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break;
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default:
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return ERR_PTR(-EOPNOTSUPP);
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}
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if (tb[NFTA_PAYLOAD_SREG] != NULL) {
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if (tb[NFTA_PAYLOAD_DREG] != NULL)
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return ERR_PTR(-EINVAL);
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return &nft_payload_set_ops;
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}
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if (tb[NFTA_PAYLOAD_DREG] == NULL)
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return ERR_PTR(-EINVAL);
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offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
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len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
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if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
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base != NFT_PAYLOAD_LL_HEADER)
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return &nft_payload_fast_ops;
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else
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return &nft_payload_ops;
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}
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struct nft_expr_type nft_payload_type __read_mostly = {
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.name = "payload",
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.select_ops = nft_payload_select_ops,
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.policy = nft_payload_policy,
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.maxattr = NFTA_PAYLOAD_MAX,
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.owner = THIS_MODULE,
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};
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