make payload expression aware of the fact that VLAN offload may have removed a vlan header. When we encounter tagged skb, transparently insert the tag into the register so that vlan header matching can work without userspace being aware of offload features. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
213 lines
5.4 KiB
C
213 lines
5.4 KiB
C
/*
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* Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
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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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/* 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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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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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_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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};
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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 struct nft_expr_type nft_payload_type;
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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 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_DREG] == NULL ||
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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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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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static 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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int __init nft_payload_module_init(void)
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{
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return nft_register_expr(&nft_payload_type);
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}
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void nft_payload_module_exit(void)
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{
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nft_unregister_expr(&nft_payload_type);
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}
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