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![Florian Westphal](/assets/img/avatar_default.png)
These NLA_U32 types get stored in u8 fields, reject invalid values instead of silently casting to u8. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
358 lines
9.1 KiB
C
358 lines
9.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/module.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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#include <net/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_tproxy.h>
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#include <net/inet_sock.h>
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#include <net/tcp.h>
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#include <linux/if_ether.h>
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#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
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#endif
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struct nft_tproxy {
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u8 sreg_addr;
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u8 sreg_port;
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u8 family;
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};
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static void nft_tproxy_eval_v4(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_tproxy *priv = nft_expr_priv(expr);
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struct sk_buff *skb = pkt->skb;
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const struct iphdr *iph = ip_hdr(skb);
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struct udphdr _hdr, *hp;
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__be32 taddr = 0;
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__be16 tport = 0;
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struct sock *sk;
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if (pkt->tprot != IPPROTO_TCP &&
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pkt->tprot != IPPROTO_UDP) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
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if (!hp) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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/* check if there's an ongoing connection on the packet addresses, this
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* happens if the redirect already happened and the current packet
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* belongs to an already established connection
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*/
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sk = nf_tproxy_get_sock_v4(nft_net(pkt), skb, iph->protocol,
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iph->saddr, iph->daddr,
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hp->source, hp->dest,
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skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED);
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if (priv->sreg_addr)
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taddr = nft_reg_load_be32(®s->data[priv->sreg_addr]);
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taddr = nf_tproxy_laddr4(skb, taddr, iph->daddr);
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if (priv->sreg_port)
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tport = nft_reg_load_be16(®s->data[priv->sreg_port]);
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if (!tport)
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tport = hp->dest;
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/* UDP has no TCP_TIME_WAIT state, so we never enter here */
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if (sk && sk->sk_state == TCP_TIME_WAIT) {
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/* reopening a TIME_WAIT connection needs special handling */
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sk = nf_tproxy_handle_time_wait4(nft_net(pkt), skb, taddr, tport, sk);
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} else if (!sk) {
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/* no, there's no established connection, check if
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* there's a listener on the redirected addr/port
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*/
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sk = nf_tproxy_get_sock_v4(nft_net(pkt), skb, iph->protocol,
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iph->saddr, taddr,
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hp->source, tport,
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skb->dev, NF_TPROXY_LOOKUP_LISTENER);
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}
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if (sk && nf_tproxy_sk_is_transparent(sk))
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nf_tproxy_assign_sock(skb, sk);
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else
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regs->verdict.code = NFT_BREAK;
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}
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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static void nft_tproxy_eval_v6(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_tproxy *priv = nft_expr_priv(expr);
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struct sk_buff *skb = pkt->skb;
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const struct ipv6hdr *iph = ipv6_hdr(skb);
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int thoff = nft_thoff(pkt);
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struct udphdr _hdr, *hp;
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struct in6_addr taddr;
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__be16 tport = 0;
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struct sock *sk;
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int l4proto;
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memset(&taddr, 0, sizeof(taddr));
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if (pkt->tprot != IPPROTO_TCP &&
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pkt->tprot != IPPROTO_UDP) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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l4proto = pkt->tprot;
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hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
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if (hp == NULL) {
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regs->verdict.code = NFT_BREAK;
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return;
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}
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/* check if there's an ongoing connection on the packet addresses, this
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* happens if the redirect already happened and the current packet
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* belongs to an already established connection
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*/
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sk = nf_tproxy_get_sock_v6(nft_net(pkt), skb, thoff, l4proto,
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&iph->saddr, &iph->daddr,
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hp->source, hp->dest,
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nft_in(pkt), NF_TPROXY_LOOKUP_ESTABLISHED);
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if (priv->sreg_addr)
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memcpy(&taddr, ®s->data[priv->sreg_addr], sizeof(taddr));
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taddr = *nf_tproxy_laddr6(skb, &taddr, &iph->daddr);
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if (priv->sreg_port)
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tport = nft_reg_load_be16(®s->data[priv->sreg_port]);
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if (!tport)
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tport = hp->dest;
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/* UDP has no TCP_TIME_WAIT state, so we never enter here */
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if (sk && sk->sk_state == TCP_TIME_WAIT) {
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/* reopening a TIME_WAIT connection needs special handling */
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sk = nf_tproxy_handle_time_wait6(skb, l4proto, thoff,
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nft_net(pkt),
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&taddr,
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tport,
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sk);
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} else if (!sk) {
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/* no there's no established connection, check if
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* there's a listener on the redirected addr/port
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*/
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sk = nf_tproxy_get_sock_v6(nft_net(pkt), skb, thoff,
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l4proto, &iph->saddr, &taddr,
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hp->source, tport,
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nft_in(pkt), NF_TPROXY_LOOKUP_LISTENER);
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}
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/* NOTE: assign_sock consumes our sk reference */
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if (sk && nf_tproxy_sk_is_transparent(sk))
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nf_tproxy_assign_sock(skb, sk);
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else
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regs->verdict.code = NFT_BREAK;
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}
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#endif
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static void nft_tproxy_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_tproxy *priv = nft_expr_priv(expr);
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switch (nft_pf(pkt)) {
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case NFPROTO_IPV4:
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switch (priv->family) {
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case NFPROTO_IPV4:
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case NFPROTO_UNSPEC:
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nft_tproxy_eval_v4(expr, regs, pkt);
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return;
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}
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break;
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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case NFPROTO_IPV6:
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switch (priv->family) {
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case NFPROTO_IPV6:
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case NFPROTO_UNSPEC:
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nft_tproxy_eval_v6(expr, regs, pkt);
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return;
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}
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#endif
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}
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regs->verdict.code = NFT_BREAK;
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}
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static const struct nla_policy nft_tproxy_policy[NFTA_TPROXY_MAX + 1] = {
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[NFTA_TPROXY_FAMILY] = NLA_POLICY_MAX(NLA_BE32, 255),
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[NFTA_TPROXY_REG_ADDR] = { .type = NLA_U32 },
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[NFTA_TPROXY_REG_PORT] = { .type = NLA_U32 },
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};
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static int nft_tproxy_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_tproxy *priv = nft_expr_priv(expr);
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unsigned int alen = 0;
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int err;
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if (!tb[NFTA_TPROXY_FAMILY] ||
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(!tb[NFTA_TPROXY_REG_ADDR] && !tb[NFTA_TPROXY_REG_PORT]))
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return -EINVAL;
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priv->family = ntohl(nla_get_be32(tb[NFTA_TPROXY_FAMILY]));
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switch (ctx->family) {
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case NFPROTO_IPV4:
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if (priv->family != NFPROTO_IPV4)
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return -EINVAL;
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break;
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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case NFPROTO_IPV6:
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if (priv->family != NFPROTO_IPV6)
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return -EINVAL;
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break;
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#endif
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case NFPROTO_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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/* Address is specified but the rule family is not set accordingly */
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if (priv->family == NFPROTO_UNSPEC && tb[NFTA_TPROXY_REG_ADDR])
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return -EINVAL;
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switch (priv->family) {
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case NFPROTO_IPV4:
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alen = sizeof_field(union nf_inet_addr, in);
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err = nf_defrag_ipv4_enable(ctx->net);
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if (err)
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return err;
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break;
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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case NFPROTO_IPV6:
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alen = sizeof_field(union nf_inet_addr, in6);
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err = nf_defrag_ipv6_enable(ctx->net);
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if (err)
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return err;
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break;
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#endif
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case NFPROTO_UNSPEC:
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/* No address is specified here */
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err = nf_defrag_ipv4_enable(ctx->net);
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if (err)
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return err;
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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err = nf_defrag_ipv6_enable(ctx->net);
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if (err)
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return err;
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#endif
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break;
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default:
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return -EOPNOTSUPP;
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}
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if (tb[NFTA_TPROXY_REG_ADDR]) {
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err = nft_parse_register_load(tb[NFTA_TPROXY_REG_ADDR],
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&priv->sreg_addr, alen);
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if (err < 0)
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return err;
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}
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if (tb[NFTA_TPROXY_REG_PORT]) {
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err = nft_parse_register_load(tb[NFTA_TPROXY_REG_PORT],
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&priv->sreg_port, sizeof(u16));
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if (err < 0)
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return err;
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}
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return 0;
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}
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static void nft_tproxy_destroy(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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const struct nft_tproxy *priv = nft_expr_priv(expr);
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switch (priv->family) {
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case NFPROTO_IPV4:
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nf_defrag_ipv4_disable(ctx->net);
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break;
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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case NFPROTO_IPV6:
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nf_defrag_ipv6_disable(ctx->net);
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break;
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#endif
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case NFPROTO_UNSPEC:
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nf_defrag_ipv4_disable(ctx->net);
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#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
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nf_defrag_ipv6_disable(ctx->net);
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#endif
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break;
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}
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}
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static int nft_tproxy_dump(struct sk_buff *skb,
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const struct nft_expr *expr, bool reset)
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{
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const struct nft_tproxy *priv = nft_expr_priv(expr);
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if (nla_put_be32(skb, NFTA_TPROXY_FAMILY, htonl(priv->family)))
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return -1;
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if (priv->sreg_addr &&
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nft_dump_register(skb, NFTA_TPROXY_REG_ADDR, priv->sreg_addr))
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return -1;
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if (priv->sreg_port &&
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nft_dump_register(skb, NFTA_TPROXY_REG_PORT, priv->sreg_port))
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return -1;
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return 0;
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}
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static int nft_tproxy_validate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nft_data **data)
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{
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return nft_chain_validate_hooks(ctx->chain, 1 << NF_INET_PRE_ROUTING);
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}
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static struct nft_expr_type nft_tproxy_type;
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static const struct nft_expr_ops nft_tproxy_ops = {
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.type = &nft_tproxy_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_tproxy)),
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.eval = nft_tproxy_eval,
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.init = nft_tproxy_init,
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.destroy = nft_tproxy_destroy,
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.dump = nft_tproxy_dump,
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.reduce = NFT_REDUCE_READONLY,
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.validate = nft_tproxy_validate,
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};
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static struct nft_expr_type nft_tproxy_type __read_mostly = {
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.name = "tproxy",
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.ops = &nft_tproxy_ops,
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.policy = nft_tproxy_policy,
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.maxattr = NFTA_TPROXY_MAX,
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.owner = THIS_MODULE,
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};
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static int __init nft_tproxy_module_init(void)
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{
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return nft_register_expr(&nft_tproxy_type);
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}
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static void __exit nft_tproxy_module_exit(void)
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{
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nft_unregister_expr(&nft_tproxy_type);
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}
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module_init(nft_tproxy_module_init);
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module_exit(nft_tproxy_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Máté Eckl");
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MODULE_DESCRIPTION("nf_tables tproxy support module");
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MODULE_ALIAS_NFT_EXPR("tproxy");
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