// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
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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 <asm/unaligned.h>
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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/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_tables.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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u8 dreg;
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u8 sreg;
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u8 flags;
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};
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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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struct nft_exthdr *priv = nft_expr_priv(expr);
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u32 *dest = ®s->data[priv->dreg];
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unsigned int offset = 0;
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int err;
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if (pkt->skb->protocol != htons(ETH_P_IPV6))
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goto err;
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err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
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if (priv->flags & NFT_EXTHDR_F_PRESENT) {
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nft_reg_store8(dest, err >= 0);
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return;
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} else if (err < 0) {
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goto err;
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}
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offset += priv->offset;
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dest[priv->len / NFT_REG32_SIZE] = 0;
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if (skb_copy_bits(pkt->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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/* find the offset to specified option.
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*
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* If target header is found, its offset is set in *offset and return option
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* number. Otherwise, return negative error.
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*
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* If the first fragment doesn't contain the End of Options it is considered
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* invalid.
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*/
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static int ipv4_find_option(struct net *net, struct sk_buff *skb,
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unsigned int *offset, int target)
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{
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unsigned char optbuf[sizeof(struct ip_options) + 40];
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struct ip_options *opt = (struct ip_options *)optbuf;
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struct iphdr *iph, _iph;
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unsigned int start;
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bool found = false;
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__be32 info;
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int optlen;
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iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
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if (!iph)
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return -EBADMSG;
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start = sizeof(struct iphdr);
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optlen = iph->ihl * 4 - (int)sizeof(struct iphdr);
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if (optlen <= 0)
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return -ENOENT;
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memset(opt, 0, sizeof(struct ip_options));
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/* Copy the options since __ip_options_compile() modifies
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* the options.
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*/
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if (skb_copy_bits(skb, start, opt->__data, optlen))
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return -EBADMSG;
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opt->optlen = optlen;
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if (__ip_options_compile(net, opt, NULL, &info))
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return -EBADMSG;
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switch (target) {
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case IPOPT_SSRR:
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case IPOPT_LSRR:
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if (!opt->srr)
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break;
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found = target == IPOPT_SSRR ? opt->is_strictroute :
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!opt->is_strictroute;
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if (found)
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*offset = opt->srr + start;
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break;
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case IPOPT_RR:
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if (!opt->rr)
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break;
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*offset = opt->rr + start;
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found = true;
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break;
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case IPOPT_RA:
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if (!opt->router_alert)
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break;
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*offset = opt->router_alert + start;
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found = true;
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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 found ? target : -ENOENT;
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}
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static void nft_exthdr_ipv4_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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struct nft_exthdr *priv = nft_expr_priv(expr);
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u32 *dest = ®s->data[priv->dreg];
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struct sk_buff *skb = pkt->skb;
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unsigned int offset;
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int err;
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if (skb->protocol != htons(ETH_P_IP))
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goto err;
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err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type);
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if (priv->flags & NFT_EXTHDR_F_PRESENT) {
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nft_reg_store8(dest, err >= 0);
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return;
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} else if (err < 0) {
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goto err;
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}
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offset += priv->offset;
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dest[priv->len / NFT_REG32_SIZE] = 0;
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if (skb_copy_bits(pkt->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 void *
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nft_tcp_header_pointer(const struct nft_pktinfo *pkt,
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unsigned int len, void *buffer, unsigned int *tcphdr_len)
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{
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struct tcphdr *tcph;
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if (!pkt->tprot_set || pkt->tprot != IPPROTO_TCP)
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return NULL;
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tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buffer);
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if (!tcph)
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return NULL;
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*tcphdr_len = __tcp_hdrlen(tcph);
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if (*tcphdr_len < sizeof(*tcph) || *tcphdr_len > len)
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return NULL;
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return skb_header_pointer(pkt->skb, pkt->xt.thoff, *tcphdr_len, buffer);
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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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tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
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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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if (priv->flags & NFT_EXTHDR_F_PRESENT) {
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*dest = 1;
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} else {
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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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}
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return;
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}
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err:
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if (priv->flags & NFT_EXTHDR_F_PRESENT)
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*dest = 0;
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else
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regs->verdict.code = NFT_BREAK;
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}
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static void nft_exthdr_tcp_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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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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struct tcphdr *tcph;
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u8 *opt;
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tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
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if (!tcph)
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return;
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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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union {
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__be16 v16;
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__be32 v32;
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} old, new;
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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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return;
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if (skb_ensure_writable(pkt->skb,
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pkt->xt.thoff + i + priv->len))
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return;
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tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff,
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&tcphdr_len);
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if (!tcph)
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return;
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offset = i + priv->offset;
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switch (priv->len) {
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case 2:
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old.v16 = get_unaligned((u16 *)(opt + offset));
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new.v16 = (__force __be16)nft_reg_load16(
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®s->data[priv->sreg]);
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switch (priv->type) {
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case TCPOPT_MSS:
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/* increase can cause connection to stall */
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if (ntohs(old.v16) <= ntohs(new.v16))
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return;
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break;
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}
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if (old.v16 == new.v16)
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return;
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put_unaligned(new.v16, (u16*)(opt + offset));
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inet_proto_csum_replace2(&tcph->check, pkt->skb,
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old.v16, new.v16, false);
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break;
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case 4:
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new.v32 = regs->data[priv->sreg];
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old.v32 = get_unaligned((u32 *)(opt + offset));
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if (old.v32 == new.v32)
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return;
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put_unaligned(new.v32, (u32*)(opt + offset));
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inet_proto_csum_replace4(&tcph->check, pkt->skb,
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old.v32, new.v32, false);
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break;
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default:
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WARN_ON_ONCE(1);
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break;
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}
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return;
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}
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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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[NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
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[NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
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[NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 },
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[NFTA_EXTHDR_OP] = { .type = NLA_U32 },
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[NFTA_EXTHDR_SREG] = { .type = NLA_U32 },
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};
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static int nft_exthdr_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_exthdr *priv = nft_expr_priv(expr);
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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] ||
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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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if (err < 0)
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return err;
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err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
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if (err < 0)
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return err;
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if (tb[NFTA_EXTHDR_FLAGS]) {
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err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
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if (err < 0)
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return err;
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if (flags & ~NFT_EXTHDR_F_PRESENT)
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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->flags = flags;
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priv->op = op;
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return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG],
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&priv->dreg, NULL, NFT_DATA_VALUE,
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priv->len);
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}
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static int nft_exthdr_tcp_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_exthdr *priv = nft_expr_priv(expr);
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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_SREG] ||
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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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if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS])
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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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if (err < 0)
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return err;
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err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
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if (err < 0)
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return err;
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if (offset < 2)
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return -EOPNOTSUPP;
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switch (len) {
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case 2: break;
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case 4: break;
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default:
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return -EOPNOTSUPP;
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}
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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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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->flags = flags;
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priv->op = op;
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return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg,
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priv->len);
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}
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static int nft_exthdr_ipv4_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_exthdr *priv = nft_expr_priv(expr);
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int err = nft_exthdr_init(ctx, expr, tb);
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if (err < 0)
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return err;
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switch (priv->type) {
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case IPOPT_SSRR:
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case IPOPT_LSRR:
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case IPOPT_RR:
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case IPOPT_RA:
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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 0;
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}
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static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv)
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{
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if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
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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:
|
return -1;
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}
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static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_exthdr *priv = nft_expr_priv(expr);
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if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
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return -1;
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return nft_exthdr_dump_common(skb, priv);
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}
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static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_exthdr *priv = nft_expr_priv(expr);
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if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg))
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return -1;
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return nft_exthdr_dump_common(skb, priv);
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}
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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_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_ipv4_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_ipv4_eval,
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.init = nft_exthdr_ipv4_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,
|
.dump = nft_exthdr_dump,
|
};
|
|
static const struct nft_expr_ops nft_exthdr_tcp_set_ops = {
|
.type = &nft_exthdr_type,
|
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
|
.eval = nft_exthdr_tcp_set_eval,
|
.init = nft_exthdr_tcp_set_init,
|
.dump = nft_exthdr_dump_set,
|
};
|
|
static const struct nft_expr_ops *
|
nft_exthdr_select_ops(const struct nft_ctx *ctx,
|
const struct nlattr * const tb[])
|
{
|
u32 op;
|
|
if (!tb[NFTA_EXTHDR_OP])
|
return &nft_exthdr_ipv6_ops;
|
|
if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG])
|
return ERR_PTR(-EOPNOTSUPP);
|
|
op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP]));
|
switch (op) {
|
case NFT_EXTHDR_OP_TCPOPT:
|
if (tb[NFTA_EXTHDR_SREG])
|
return &nft_exthdr_tcp_set_ops;
|
if (tb[NFTA_EXTHDR_DREG])
|
return &nft_exthdr_tcp_ops;
|
break;
|
case NFT_EXTHDR_OP_IPV6:
|
if (tb[NFTA_EXTHDR_DREG])
|
return &nft_exthdr_ipv6_ops;
|
break;
|
case NFT_EXTHDR_OP_IPV4:
|
if (ctx->family != NFPROTO_IPV6) {
|
if (tb[NFTA_EXTHDR_DREG])
|
return &nft_exthdr_ipv4_ops;
|
}
|
break;
|
}
|
|
return ERR_PTR(-EOPNOTSUPP);
|
}
|
|
struct nft_expr_type nft_exthdr_type __read_mostly = {
|
.name = "exthdr",
|
.select_ops = nft_exthdr_select_ops,
|
.policy = nft_exthdr_policy,
|
.maxattr = NFTA_EXTHDR_MAX,
|
.owner = THIS_MODULE,
|
};
|
