// SPDX-License-Identifier: GPL-2.0-only
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/types.h>
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#include <linux/timer.h>
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#include <linux/module.h>
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#include <linux/udp.h>
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#include <linux/seq_file.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <net/ip6_checksum.h>
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#include <net/checksum.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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#include <net/netfilter/nf_conntrack_timeout.h>
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#include <net/netfilter/nf_log.h>
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#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
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#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
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static const unsigned int udp_timeouts[UDP_CT_MAX] = {
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[UDP_CT_UNREPLIED] = 30*HZ,
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[UDP_CT_REPLIED] = 120*HZ,
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};
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static unsigned int *udp_get_timeouts(struct net *net)
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{
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return nf_udp_pernet(net)->timeouts;
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}
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static void udp_error_log(const struct sk_buff *skb,
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const struct nf_hook_state *state,
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const char *msg)
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{
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nf_l4proto_log_invalid(skb, state->net, state->pf,
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IPPROTO_UDP, "%s", msg);
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}
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static bool udp_error(struct sk_buff *skb,
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unsigned int dataoff,
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const struct nf_hook_state *state)
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{
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unsigned int udplen = skb->len - dataoff;
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const struct udphdr *hdr;
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struct udphdr _hdr;
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/* Header is too small? */
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hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
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if (!hdr) {
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udp_error_log(skb, state, "short packet");
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return true;
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}
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/* Truncated/malformed packets */
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if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
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udp_error_log(skb, state, "truncated/malformed packet");
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return true;
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}
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/* Packet with no checksum */
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if (!hdr->check)
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return false;
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/* Checksum invalid? Ignore.
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* We skip checking packets on the outgoing path
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* because the checksum is assumed to be correct.
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* FIXME: Source route IP option packets --RR */
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if (state->hook == NF_INET_PRE_ROUTING &&
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state->net->ct.sysctl_checksum &&
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nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
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udp_error_log(skb, state, "bad checksum");
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return true;
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}
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return false;
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}
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/* Returns verdict for packet, and may modify conntracktype */
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int nf_conntrack_udp_packet(struct nf_conn *ct,
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struct sk_buff *skb,
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unsigned int dataoff,
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enum ip_conntrack_info ctinfo,
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const struct nf_hook_state *state)
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{
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unsigned int *timeouts;
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if (udp_error(skb, dataoff, state))
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return -NF_ACCEPT;
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timeouts = nf_ct_timeout_lookup(ct);
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if (!timeouts)
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timeouts = udp_get_timeouts(nf_ct_net(ct));
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if (!nf_ct_is_confirmed(ct))
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ct->proto.udp.stream_ts = 2 * HZ + jiffies;
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/* If we've seen traffic both ways, this is some kind of UDP
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* stream. Set Assured.
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*/
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if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
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unsigned long extra = timeouts[UDP_CT_UNREPLIED];
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bool stream = false;
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/* Still active after two seconds? Extend timeout. */
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if (time_after(jiffies, ct->proto.udp.stream_ts)) {
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extra = timeouts[UDP_CT_REPLIED];
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stream = true;
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}
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nf_ct_refresh_acct(ct, ctinfo, skb, extra);
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/* never set ASSURED for IPS_NAT_CLASH, they time out soon */
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if (unlikely((ct->status & IPS_NAT_CLASH)))
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return NF_ACCEPT;
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/* Also, more likely to be important, and not a probe */
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if (stream && !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
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nf_conntrack_event_cache(IPCT_ASSURED, ct);
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} else {
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nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
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}
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return NF_ACCEPT;
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}
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#ifdef CONFIG_NF_CT_PROTO_UDPLITE
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static void udplite_error_log(const struct sk_buff *skb,
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const struct nf_hook_state *state,
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const char *msg)
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{
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nf_l4proto_log_invalid(skb, state->net, state->pf,
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IPPROTO_UDPLITE, "%s", msg);
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}
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static bool udplite_error(struct sk_buff *skb,
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unsigned int dataoff,
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const struct nf_hook_state *state)
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{
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unsigned int udplen = skb->len - dataoff;
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const struct udphdr *hdr;
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struct udphdr _hdr;
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unsigned int cscov;
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/* Header is too small? */
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hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
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if (!hdr) {
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udplite_error_log(skb, state, "short packet");
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return true;
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}
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cscov = ntohs(hdr->len);
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if (cscov == 0) {
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cscov = udplen;
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} else if (cscov < sizeof(*hdr) || cscov > udplen) {
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udplite_error_log(skb, state, "invalid checksum coverage");
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return true;
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}
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/* UDPLITE mandates checksums */
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if (!hdr->check) {
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udplite_error_log(skb, state, "checksum missing");
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return true;
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}
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/* Checksum invalid? Ignore. */
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if (state->hook == NF_INET_PRE_ROUTING &&
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state->net->ct.sysctl_checksum &&
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nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
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state->pf)) {
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udplite_error_log(skb, state, "bad checksum");
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return true;
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}
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return false;
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}
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/* Returns verdict for packet, and may modify conntracktype */
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int nf_conntrack_udplite_packet(struct nf_conn *ct,
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struct sk_buff *skb,
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unsigned int dataoff,
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enum ip_conntrack_info ctinfo,
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const struct nf_hook_state *state)
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{
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unsigned int *timeouts;
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if (udplite_error(skb, dataoff, state))
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return -NF_ACCEPT;
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timeouts = nf_ct_timeout_lookup(ct);
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if (!timeouts)
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timeouts = udp_get_timeouts(nf_ct_net(ct));
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/* If we've seen traffic both ways, this is some kind of UDP
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stream. Extend timeout. */
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if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
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nf_ct_refresh_acct(ct, ctinfo, skb,
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timeouts[UDP_CT_REPLIED]);
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if (unlikely((ct->status & IPS_NAT_CLASH)))
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return NF_ACCEPT;
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/* Also, more likely to be important, and not a probe */
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if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
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nf_conntrack_event_cache(IPCT_ASSURED, ct);
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} else {
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nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
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}
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return NF_ACCEPT;
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}
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#endif
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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#include <linux/netfilter/nfnetlink.h>
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#include <linux/netfilter/nfnetlink_cttimeout.h>
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static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
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struct net *net, void *data)
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{
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unsigned int *timeouts = data;
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struct nf_udp_net *un = nf_udp_pernet(net);
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if (!timeouts)
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timeouts = un->timeouts;
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/* set default timeouts for UDP. */
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timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
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timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
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if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
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timeouts[UDP_CT_UNREPLIED] =
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ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
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}
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if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
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timeouts[UDP_CT_REPLIED] =
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ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
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}
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return 0;
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}
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static int
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udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
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{
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const unsigned int *timeouts = data;
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if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
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htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
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nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
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htonl(timeouts[UDP_CT_REPLIED] / HZ)))
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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 -ENOSPC;
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}
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static const struct nla_policy
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udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
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[CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 },
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[CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 },
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};
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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void nf_conntrack_udp_init_net(struct net *net)
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{
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struct nf_udp_net *un = nf_udp_pernet(net);
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int i;
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for (i = 0; i < UDP_CT_MAX; i++)
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un->timeouts[i] = udp_timeouts[i];
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}
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const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
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{
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.l4proto = IPPROTO_UDP,
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.allow_clash = true,
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
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.tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
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.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
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.nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
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.nla_policy = nf_ct_port_nla_policy,
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#endif
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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.ctnl_timeout = {
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.nlattr_to_obj = udp_timeout_nlattr_to_obj,
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.obj_to_nlattr = udp_timeout_obj_to_nlattr,
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.nlattr_max = CTA_TIMEOUT_UDP_MAX,
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.obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
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.nla_policy = udp_timeout_nla_policy,
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},
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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};
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#ifdef CONFIG_NF_CT_PROTO_UDPLITE
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const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
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{
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.l4proto = IPPROTO_UDPLITE,
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.allow_clash = true,
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
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.tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
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.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
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.nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
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.nla_policy = nf_ct_port_nla_policy,
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#endif
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#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
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.ctnl_timeout = {
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.nlattr_to_obj = udp_timeout_nlattr_to_obj,
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.obj_to_nlattr = udp_timeout_obj_to_nlattr,
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.nlattr_max = CTA_TIMEOUT_UDP_MAX,
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.obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
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.nla_policy = udp_timeout_nla_policy,
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},
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#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
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};
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#endif
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