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![Kuniyuki Iwashima](/assets/img/avatar_default.png)
While reading sysctl_ip_default_ttl, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: 1da177e4c3
("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1220 lines
30 KiB
C
1220 lines
30 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <asm/unaligned.h>
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#include <net/tcp.h>
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#include <net/netns/generic.h>
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#include <linux/proc_fs.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter/nf_synproxy.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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#include <net/netfilter/nf_conntrack_extend.h>
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#include <net/netfilter/nf_conntrack_seqadj.h>
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#include <net/netfilter/nf_conntrack_synproxy.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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#include <net/netfilter/nf_synproxy.h>
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unsigned int synproxy_net_id;
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EXPORT_SYMBOL_GPL(synproxy_net_id);
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bool
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synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
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const struct tcphdr *th, struct synproxy_options *opts)
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{
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int length = (th->doff * 4) - sizeof(*th);
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u8 buf[40], *ptr;
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if (unlikely(length < 0))
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return false;
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ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
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if (ptr == NULL)
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return false;
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opts->options = 0;
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while (length > 0) {
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int opcode = *ptr++;
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int opsize;
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switch (opcode) {
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case TCPOPT_EOL:
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return true;
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case TCPOPT_NOP:
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length--;
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continue;
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default:
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if (length < 2)
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return true;
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opsize = *ptr++;
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if (opsize < 2)
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return true;
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if (opsize > length)
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return true;
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switch (opcode) {
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case TCPOPT_MSS:
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if (opsize == TCPOLEN_MSS) {
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opts->mss_option = get_unaligned_be16(ptr);
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opts->options |= NF_SYNPROXY_OPT_MSS;
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}
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break;
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case TCPOPT_WINDOW:
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if (opsize == TCPOLEN_WINDOW) {
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opts->wscale = *ptr;
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if (opts->wscale > TCP_MAX_WSCALE)
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opts->wscale = TCP_MAX_WSCALE;
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opts->options |= NF_SYNPROXY_OPT_WSCALE;
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}
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break;
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case TCPOPT_TIMESTAMP:
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if (opsize == TCPOLEN_TIMESTAMP) {
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opts->tsval = get_unaligned_be32(ptr);
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opts->tsecr = get_unaligned_be32(ptr + 4);
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opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
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}
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break;
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case TCPOPT_SACK_PERM:
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if (opsize == TCPOLEN_SACK_PERM)
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opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
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break;
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}
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ptr += opsize - 2;
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length -= opsize;
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}
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}
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return true;
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}
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EXPORT_SYMBOL_GPL(synproxy_parse_options);
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static unsigned int
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synproxy_options_size(const struct synproxy_options *opts)
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{
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unsigned int size = 0;
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if (opts->options & NF_SYNPROXY_OPT_MSS)
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size += TCPOLEN_MSS_ALIGNED;
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if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
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size += TCPOLEN_TSTAMP_ALIGNED;
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else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
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size += TCPOLEN_SACKPERM_ALIGNED;
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if (opts->options & NF_SYNPROXY_OPT_WSCALE)
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size += TCPOLEN_WSCALE_ALIGNED;
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return size;
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}
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static void
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synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
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{
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__be32 *ptr = (__be32 *)(th + 1);
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u8 options = opts->options;
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if (options & NF_SYNPROXY_OPT_MSS)
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*ptr++ = htonl((TCPOPT_MSS << 24) |
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(TCPOLEN_MSS << 16) |
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opts->mss_option);
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if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
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if (options & NF_SYNPROXY_OPT_SACK_PERM)
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*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
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(TCPOLEN_SACK_PERM << 16) |
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(TCPOPT_TIMESTAMP << 8) |
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TCPOLEN_TIMESTAMP);
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else
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*ptr++ = htonl((TCPOPT_NOP << 24) |
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(TCPOPT_NOP << 16) |
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(TCPOPT_TIMESTAMP << 8) |
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TCPOLEN_TIMESTAMP);
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*ptr++ = htonl(opts->tsval);
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*ptr++ = htonl(opts->tsecr);
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} else if (options & NF_SYNPROXY_OPT_SACK_PERM)
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*ptr++ = htonl((TCPOPT_NOP << 24) |
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(TCPOPT_NOP << 16) |
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(TCPOPT_SACK_PERM << 8) |
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TCPOLEN_SACK_PERM);
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if (options & NF_SYNPROXY_OPT_WSCALE)
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*ptr++ = htonl((TCPOPT_NOP << 24) |
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(TCPOPT_WINDOW << 16) |
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(TCPOLEN_WINDOW << 8) |
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opts->wscale);
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}
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void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
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struct synproxy_options *opts)
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{
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opts->tsecr = opts->tsval;
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opts->tsval = tcp_time_stamp_raw() & ~0x3f;
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if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
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opts->tsval |= opts->wscale;
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opts->wscale = info->wscale;
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} else
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opts->tsval |= 0xf;
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if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
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opts->tsval |= 1 << 4;
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if (opts->options & NF_SYNPROXY_OPT_ECN)
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opts->tsval |= 1 << 5;
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}
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EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
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static void
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synproxy_check_timestamp_cookie(struct synproxy_options *opts)
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{
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opts->wscale = opts->tsecr & 0xf;
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if (opts->wscale != 0xf)
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opts->options |= NF_SYNPROXY_OPT_WSCALE;
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opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
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opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
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}
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static unsigned int
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synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
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struct tcphdr *th, struct nf_conn *ct,
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enum ip_conntrack_info ctinfo,
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const struct nf_conn_synproxy *synproxy)
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{
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unsigned int optoff, optend;
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__be32 *ptr, old;
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if (synproxy->tsoff == 0)
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return 1;
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optoff = protoff + sizeof(struct tcphdr);
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optend = protoff + th->doff * 4;
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if (skb_ensure_writable(skb, optend))
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return 0;
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while (optoff < optend) {
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unsigned char *op = skb->data + optoff;
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switch (op[0]) {
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case TCPOPT_EOL:
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return 1;
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case TCPOPT_NOP:
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optoff++;
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continue;
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default:
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if (optoff + 1 == optend ||
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optoff + op[1] > optend ||
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op[1] < 2)
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return 0;
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if (op[0] == TCPOPT_TIMESTAMP &&
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op[1] == TCPOLEN_TIMESTAMP) {
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if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
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ptr = (__be32 *)&op[2];
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old = *ptr;
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*ptr = htonl(ntohl(*ptr) -
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synproxy->tsoff);
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} else {
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ptr = (__be32 *)&op[6];
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old = *ptr;
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*ptr = htonl(ntohl(*ptr) +
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synproxy->tsoff);
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}
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inet_proto_csum_replace4(&th->check, skb,
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old, *ptr, false);
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return 1;
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}
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optoff += op[1];
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}
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}
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return 1;
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}
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#ifdef CONFIG_PROC_FS
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static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
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int cpu;
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if (*pos == 0)
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return SEQ_START_TOKEN;
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for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
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if (!cpu_possible(cpu))
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continue;
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*pos = cpu + 1;
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return per_cpu_ptr(snet->stats, cpu);
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}
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return NULL;
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}
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static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
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int cpu;
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for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
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if (!cpu_possible(cpu))
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continue;
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*pos = cpu + 1;
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return per_cpu_ptr(snet->stats, cpu);
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}
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(*pos)++;
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return NULL;
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}
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static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
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{
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return;
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}
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static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
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{
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struct synproxy_stats *stats = v;
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if (v == SEQ_START_TOKEN) {
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seq_puts(seq, "entries\t\tsyn_received\t"
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"cookie_invalid\tcookie_valid\t"
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"cookie_retrans\tconn_reopened\n");
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return 0;
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}
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seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
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stats->syn_received,
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stats->cookie_invalid,
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stats->cookie_valid,
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stats->cookie_retrans,
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stats->conn_reopened);
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return 0;
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}
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static const struct seq_operations synproxy_cpu_seq_ops = {
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.start = synproxy_cpu_seq_start,
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.next = synproxy_cpu_seq_next,
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.stop = synproxy_cpu_seq_stop,
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.show = synproxy_cpu_seq_show,
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};
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static int __net_init synproxy_proc_init(struct net *net)
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{
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if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
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&synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
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return -ENOMEM;
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return 0;
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}
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static void __net_exit synproxy_proc_exit(struct net *net)
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{
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remove_proc_entry("synproxy", net->proc_net_stat);
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}
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#else
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static int __net_init synproxy_proc_init(struct net *net)
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{
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return 0;
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}
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static void __net_exit synproxy_proc_exit(struct net *net)
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{
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return;
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}
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#endif /* CONFIG_PROC_FS */
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static int __net_init synproxy_net_init(struct net *net)
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{
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struct synproxy_net *snet = synproxy_pernet(net);
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struct nf_conn *ct;
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int err = -ENOMEM;
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ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
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if (!ct)
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goto err1;
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if (!nfct_seqadj_ext_add(ct))
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goto err2;
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if (!nfct_synproxy_ext_add(ct))
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goto err2;
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__set_bit(IPS_CONFIRMED_BIT, &ct->status);
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snet->tmpl = ct;
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snet->stats = alloc_percpu(struct synproxy_stats);
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if (snet->stats == NULL)
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goto err2;
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err = synproxy_proc_init(net);
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if (err < 0)
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goto err3;
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return 0;
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err3:
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free_percpu(snet->stats);
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err2:
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nf_ct_tmpl_free(ct);
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err1:
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return err;
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}
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static void __net_exit synproxy_net_exit(struct net *net)
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{
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struct synproxy_net *snet = synproxy_pernet(net);
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nf_ct_put(snet->tmpl);
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synproxy_proc_exit(net);
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free_percpu(snet->stats);
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}
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static struct pernet_operations synproxy_net_ops = {
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.init = synproxy_net_init,
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.exit = synproxy_net_exit,
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.id = &synproxy_net_id,
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.size = sizeof(struct synproxy_net),
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};
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static int __init synproxy_core_init(void)
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{
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return register_pernet_subsys(&synproxy_net_ops);
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}
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static void __exit synproxy_core_exit(void)
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{
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unregister_pernet_subsys(&synproxy_net_ops);
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}
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module_init(synproxy_core_init);
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module_exit(synproxy_core_exit);
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static struct iphdr *
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synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
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__be32 daddr)
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{
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struct iphdr *iph;
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skb_reset_network_header(skb);
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iph = skb_put(skb, sizeof(*iph));
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iph->version = 4;
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iph->ihl = sizeof(*iph) / 4;
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iph->tos = 0;
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iph->id = 0;
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iph->frag_off = htons(IP_DF);
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iph->ttl = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
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iph->protocol = IPPROTO_TCP;
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iph->check = 0;
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iph->saddr = saddr;
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iph->daddr = daddr;
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return iph;
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}
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static void
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synproxy_send_tcp(struct net *net,
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const struct sk_buff *skb, struct sk_buff *nskb,
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struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
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struct iphdr *niph, struct tcphdr *nth,
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unsigned int tcp_hdr_size)
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{
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nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
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nskb->ip_summed = CHECKSUM_PARTIAL;
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nskb->csum_start = (unsigned char *)nth - nskb->head;
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nskb->csum_offset = offsetof(struct tcphdr, check);
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skb_dst_set_noref(nskb, skb_dst(skb));
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nskb->protocol = htons(ETH_P_IP);
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if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
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goto free_nskb;
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if (nfct) {
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nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
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nf_conntrack_get(nfct);
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}
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ip_local_out(net, nskb->sk, nskb);
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return;
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free_nskb:
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kfree_skb(nskb);
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}
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|
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void
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synproxy_send_client_synack(struct net *net,
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const struct sk_buff *skb, const struct tcphdr *th,
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const struct synproxy_options *opts)
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{
|
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struct sk_buff *nskb;
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struct iphdr *iph, *niph;
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struct tcphdr *nth;
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unsigned int tcp_hdr_size;
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u16 mss = opts->mss_encode;
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iph = ip_hdr(skb);
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tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
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nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
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GFP_ATOMIC);
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if (!nskb)
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return;
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skb_reserve(nskb, MAX_TCP_HEADER);
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|
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niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
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|
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skb_reset_transport_header(nskb);
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nth = skb_put(nskb, tcp_hdr_size);
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nth->source = th->dest;
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nth->dest = th->source;
|
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nth->seq = htonl(__cookie_v4_init_sequence(iph, th, &mss));
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nth->ack_seq = htonl(ntohl(th->seq) + 1);
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tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
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if (opts->options & NF_SYNPROXY_OPT_ECN)
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tcp_flag_word(nth) |= TCP_FLAG_ECE;
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nth->doff = tcp_hdr_size / 4;
|
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nth->window = 0;
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nth->check = 0;
|
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nth->urg_ptr = 0;
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|
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synproxy_build_options(nth, opts);
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|
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synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
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IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
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}
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EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
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|
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static void
|
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synproxy_send_server_syn(struct net *net,
|
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const struct sk_buff *skb, const struct tcphdr *th,
|
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const struct synproxy_options *opts, u32 recv_seq)
|
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{
|
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struct synproxy_net *snet = synproxy_pernet(net);
|
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struct sk_buff *nskb;
|
|
struct iphdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ip_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->source;
|
|
nth->dest = th->dest;
|
|
nth->seq = htonl(recv_seq - 1);
|
|
/* ack_seq is used to relay our ISN to the synproxy hook to initialize
|
|
* sequence number translation once a connection tracking entry exists.
|
|
*/
|
|
nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
|
|
tcp_flag_word(nth) = TCP_FLAG_SYN;
|
|
if (opts->options & NF_SYNPROXY_OPT_ECN)
|
|
tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = th->window;
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
|
|
niph, nth, tcp_hdr_size);
|
|
}
|
|
|
|
static void
|
|
synproxy_send_server_ack(struct net *net,
|
|
const struct ip_ct_tcp *state,
|
|
const struct sk_buff *skb, const struct tcphdr *th,
|
|
const struct synproxy_options *opts)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct iphdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ip_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->dest;
|
|
nth->dest = th->source;
|
|
nth->seq = htonl(ntohl(th->ack_seq));
|
|
nth->ack_seq = htonl(ntohl(th->seq) + 1);
|
|
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
|
|
}
|
|
|
|
static void
|
|
synproxy_send_client_ack(struct net *net,
|
|
const struct sk_buff *skb, const struct tcphdr *th,
|
|
const struct synproxy_options *opts)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct iphdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ip_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->source;
|
|
nth->dest = th->dest;
|
|
nth->seq = htonl(ntohl(th->seq) + 1);
|
|
nth->ack_seq = th->ack_seq;
|
|
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = htons(ntohs(th->window) >> opts->wscale);
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
|
|
IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
|
|
}
|
|
|
|
bool
|
|
synproxy_recv_client_ack(struct net *net,
|
|
const struct sk_buff *skb, const struct tcphdr *th,
|
|
struct synproxy_options *opts, u32 recv_seq)
|
|
{
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
|
int mss;
|
|
|
|
mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
|
|
if (mss == 0) {
|
|
this_cpu_inc(snet->stats->cookie_invalid);
|
|
return false;
|
|
}
|
|
|
|
this_cpu_inc(snet->stats->cookie_valid);
|
|
opts->mss_option = mss;
|
|
opts->options |= NF_SYNPROXY_OPT_MSS;
|
|
|
|
if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
|
|
synproxy_check_timestamp_cookie(opts);
|
|
|
|
synproxy_send_server_syn(net, skb, th, opts, recv_seq);
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
|
|
|
|
unsigned int
|
|
ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
|
|
const struct nf_hook_state *nhs)
|
|
{
|
|
struct net *net = nhs->net;
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
|
enum ip_conntrack_info ctinfo;
|
|
struct nf_conn *ct;
|
|
struct nf_conn_synproxy *synproxy;
|
|
struct synproxy_options opts = {};
|
|
const struct ip_ct_tcp *state;
|
|
struct tcphdr *th, _th;
|
|
unsigned int thoff;
|
|
|
|
ct = nf_ct_get(skb, &ctinfo);
|
|
if (!ct)
|
|
return NF_ACCEPT;
|
|
|
|
synproxy = nfct_synproxy(ct);
|
|
if (!synproxy)
|
|
return NF_ACCEPT;
|
|
|
|
if (nf_is_loopback_packet(skb) ||
|
|
ip_hdr(skb)->protocol != IPPROTO_TCP)
|
|
return NF_ACCEPT;
|
|
|
|
thoff = ip_hdrlen(skb);
|
|
th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
|
|
if (!th)
|
|
return NF_DROP;
|
|
|
|
state = &ct->proto.tcp;
|
|
switch (state->state) {
|
|
case TCP_CONNTRACK_CLOSE:
|
|
if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
|
|
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
|
|
ntohl(th->seq) + 1);
|
|
break;
|
|
}
|
|
|
|
if (!th->syn || th->ack ||
|
|
CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
|
|
break;
|
|
|
|
/* Reopened connection - reset the sequence number and timestamp
|
|
* adjustments, they will get initialized once the connection is
|
|
* reestablished.
|
|
*/
|
|
nf_ct_seqadj_init(ct, ctinfo, 0);
|
|
synproxy->tsoff = 0;
|
|
this_cpu_inc(snet->stats->conn_reopened);
|
|
fallthrough;
|
|
case TCP_CONNTRACK_SYN_SENT:
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
return NF_DROP;
|
|
|
|
if (!th->syn && th->ack &&
|
|
CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
|
|
/* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
|
|
* therefore we need to add 1 to make the SYN sequence
|
|
* number match the one of first SYN.
|
|
*/
|
|
if (synproxy_recv_client_ack(net, skb, th, &opts,
|
|
ntohl(th->seq) + 1)) {
|
|
this_cpu_inc(snet->stats->cookie_retrans);
|
|
consume_skb(skb);
|
|
return NF_STOLEN;
|
|
} else {
|
|
return NF_DROP;
|
|
}
|
|
}
|
|
|
|
synproxy->isn = ntohl(th->ack_seq);
|
|
if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
|
|
synproxy->its = opts.tsecr;
|
|
|
|
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
|
break;
|
|
case TCP_CONNTRACK_SYN_RECV:
|
|
if (!th->syn || !th->ack)
|
|
break;
|
|
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
return NF_DROP;
|
|
|
|
if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
|
|
synproxy->tsoff = opts.tsval - synproxy->its;
|
|
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
|
}
|
|
|
|
opts.options &= ~(NF_SYNPROXY_OPT_MSS |
|
|
NF_SYNPROXY_OPT_WSCALE |
|
|
NF_SYNPROXY_OPT_SACK_PERM);
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
|
synproxy_send_server_ack(net, state, skb, th, &opts);
|
|
|
|
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
|
|
nf_conntrack_event_cache(IPCT_SEQADJ, ct);
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
|
synproxy_send_client_ack(net, skb, th, &opts);
|
|
|
|
consume_skb(skb);
|
|
return NF_STOLEN;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
|
|
return NF_ACCEPT;
|
|
}
|
|
EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
|
|
|
|
static const struct nf_hook_ops ipv4_synproxy_ops[] = {
|
|
{
|
|
.hook = ipv4_synproxy_hook,
|
|
.pf = NFPROTO_IPV4,
|
|
.hooknum = NF_INET_LOCAL_IN,
|
|
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
|
},
|
|
{
|
|
.hook = ipv4_synproxy_hook,
|
|
.pf = NFPROTO_IPV4,
|
|
.hooknum = NF_INET_POST_ROUTING,
|
|
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
|
},
|
|
};
|
|
|
|
int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
|
|
{
|
|
int err;
|
|
|
|
if (snet->hook_ref4 == 0) {
|
|
err = nf_register_net_hooks(net, ipv4_synproxy_ops,
|
|
ARRAY_SIZE(ipv4_synproxy_ops));
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
snet->hook_ref4++;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
|
|
|
|
void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
|
|
{
|
|
snet->hook_ref4--;
|
|
if (snet->hook_ref4 == 0)
|
|
nf_unregister_net_hooks(net, ipv4_synproxy_ops,
|
|
ARRAY_SIZE(ipv4_synproxy_ops));
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
|
|
|
|
#if IS_ENABLED(CONFIG_IPV6)
|
|
static struct ipv6hdr *
|
|
synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
|
|
const struct in6_addr *saddr,
|
|
const struct in6_addr *daddr)
|
|
{
|
|
struct ipv6hdr *iph;
|
|
|
|
skb_reset_network_header(skb);
|
|
iph = skb_put(skb, sizeof(*iph));
|
|
ip6_flow_hdr(iph, 0, 0);
|
|
iph->hop_limit = net->ipv6.devconf_all->hop_limit;
|
|
iph->nexthdr = IPPROTO_TCP;
|
|
iph->saddr = *saddr;
|
|
iph->daddr = *daddr;
|
|
|
|
return iph;
|
|
}
|
|
|
|
static void
|
|
synproxy_send_tcp_ipv6(struct net *net,
|
|
const struct sk_buff *skb, struct sk_buff *nskb,
|
|
struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
|
|
struct ipv6hdr *niph, struct tcphdr *nth,
|
|
unsigned int tcp_hdr_size)
|
|
{
|
|
struct dst_entry *dst;
|
|
struct flowi6 fl6;
|
|
int err;
|
|
|
|
nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
|
|
nskb->ip_summed = CHECKSUM_PARTIAL;
|
|
nskb->csum_start = (unsigned char *)nth - nskb->head;
|
|
nskb->csum_offset = offsetof(struct tcphdr, check);
|
|
|
|
memset(&fl6, 0, sizeof(fl6));
|
|
fl6.flowi6_proto = IPPROTO_TCP;
|
|
fl6.saddr = niph->saddr;
|
|
fl6.daddr = niph->daddr;
|
|
fl6.fl6_sport = nth->source;
|
|
fl6.fl6_dport = nth->dest;
|
|
security_skb_classify_flow((struct sk_buff *)skb,
|
|
flowi6_to_flowi_common(&fl6));
|
|
err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
|
|
if (err) {
|
|
goto free_nskb;
|
|
}
|
|
|
|
dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
|
|
if (IS_ERR(dst))
|
|
goto free_nskb;
|
|
|
|
skb_dst_set(nskb, dst);
|
|
|
|
if (nfct) {
|
|
nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
|
|
nf_conntrack_get(nfct);
|
|
}
|
|
|
|
ip6_local_out(net, nskb->sk, nskb);
|
|
return;
|
|
|
|
free_nskb:
|
|
kfree_skb(nskb);
|
|
}
|
|
|
|
void
|
|
synproxy_send_client_synack_ipv6(struct net *net,
|
|
const struct sk_buff *skb,
|
|
const struct tcphdr *th,
|
|
const struct synproxy_options *opts)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct ipv6hdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
u16 mss = opts->mss_encode;
|
|
|
|
iph = ipv6_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->dest;
|
|
nth->dest = th->source;
|
|
nth->seq = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
|
|
nth->ack_seq = htonl(ntohl(th->seq) + 1);
|
|
tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
|
|
if (opts->options & NF_SYNPROXY_OPT_ECN)
|
|
tcp_flag_word(nth) |= TCP_FLAG_ECE;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = 0;
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
|
|
IP_CT_ESTABLISHED_REPLY, niph, nth,
|
|
tcp_hdr_size);
|
|
}
|
|
EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
|
|
|
|
static void
|
|
synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
|
|
const struct tcphdr *th,
|
|
const struct synproxy_options *opts, u32 recv_seq)
|
|
{
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
|
struct sk_buff *nskb;
|
|
struct ipv6hdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ipv6_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->source;
|
|
nth->dest = th->dest;
|
|
nth->seq = htonl(recv_seq - 1);
|
|
/* ack_seq is used to relay our ISN to the synproxy hook to initialize
|
|
* sequence number translation once a connection tracking entry exists.
|
|
*/
|
|
nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
|
|
tcp_flag_word(nth) = TCP_FLAG_SYN;
|
|
if (opts->options & NF_SYNPROXY_OPT_ECN)
|
|
tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = th->window;
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
|
|
IP_CT_NEW, niph, nth, tcp_hdr_size);
|
|
}
|
|
|
|
static void
|
|
synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
|
|
const struct sk_buff *skb,
|
|
const struct tcphdr *th,
|
|
const struct synproxy_options *opts)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct ipv6hdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ipv6_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->dest;
|
|
nth->dest = th->source;
|
|
nth->seq = htonl(ntohl(th->ack_seq));
|
|
nth->ack_seq = htonl(ntohl(th->seq) + 1);
|
|
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
|
|
tcp_hdr_size);
|
|
}
|
|
|
|
static void
|
|
synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
|
|
const struct tcphdr *th,
|
|
const struct synproxy_options *opts)
|
|
{
|
|
struct sk_buff *nskb;
|
|
struct ipv6hdr *iph, *niph;
|
|
struct tcphdr *nth;
|
|
unsigned int tcp_hdr_size;
|
|
|
|
iph = ipv6_hdr(skb);
|
|
|
|
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
|
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
|
GFP_ATOMIC);
|
|
if (!nskb)
|
|
return;
|
|
skb_reserve(nskb, MAX_TCP_HEADER);
|
|
|
|
niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
|
|
|
|
skb_reset_transport_header(nskb);
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
|
nth->source = th->source;
|
|
nth->dest = th->dest;
|
|
nth->seq = htonl(ntohl(th->seq) + 1);
|
|
nth->ack_seq = th->ack_seq;
|
|
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
|
nth->doff = tcp_hdr_size / 4;
|
|
nth->window = htons(ntohs(th->window) >> opts->wscale);
|
|
nth->check = 0;
|
|
nth->urg_ptr = 0;
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
|
|
IP_CT_ESTABLISHED_REPLY, niph, nth,
|
|
tcp_hdr_size);
|
|
}
|
|
|
|
bool
|
|
synproxy_recv_client_ack_ipv6(struct net *net,
|
|
const struct sk_buff *skb,
|
|
const struct tcphdr *th,
|
|
struct synproxy_options *opts, u32 recv_seq)
|
|
{
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
|
int mss;
|
|
|
|
mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
|
|
if (mss == 0) {
|
|
this_cpu_inc(snet->stats->cookie_invalid);
|
|
return false;
|
|
}
|
|
|
|
this_cpu_inc(snet->stats->cookie_valid);
|
|
opts->mss_option = mss;
|
|
opts->options |= NF_SYNPROXY_OPT_MSS;
|
|
|
|
if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
|
|
synproxy_check_timestamp_cookie(opts);
|
|
|
|
synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
|
|
|
|
unsigned int
|
|
ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
|
|
const struct nf_hook_state *nhs)
|
|
{
|
|
struct net *net = nhs->net;
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
|
enum ip_conntrack_info ctinfo;
|
|
struct nf_conn *ct;
|
|
struct nf_conn_synproxy *synproxy;
|
|
struct synproxy_options opts = {};
|
|
const struct ip_ct_tcp *state;
|
|
struct tcphdr *th, _th;
|
|
__be16 frag_off;
|
|
u8 nexthdr;
|
|
int thoff;
|
|
|
|
ct = nf_ct_get(skb, &ctinfo);
|
|
if (!ct)
|
|
return NF_ACCEPT;
|
|
|
|
synproxy = nfct_synproxy(ct);
|
|
if (!synproxy)
|
|
return NF_ACCEPT;
|
|
|
|
if (nf_is_loopback_packet(skb))
|
|
return NF_ACCEPT;
|
|
|
|
nexthdr = ipv6_hdr(skb)->nexthdr;
|
|
thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
|
|
&frag_off);
|
|
if (thoff < 0 || nexthdr != IPPROTO_TCP)
|
|
return NF_ACCEPT;
|
|
|
|
th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
|
|
if (!th)
|
|
return NF_DROP;
|
|
|
|
state = &ct->proto.tcp;
|
|
switch (state->state) {
|
|
case TCP_CONNTRACK_CLOSE:
|
|
if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
|
|
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
|
|
ntohl(th->seq) + 1);
|
|
break;
|
|
}
|
|
|
|
if (!th->syn || th->ack ||
|
|
CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
|
|
break;
|
|
|
|
/* Reopened connection - reset the sequence number and timestamp
|
|
* adjustments, they will get initialized once the connection is
|
|
* reestablished.
|
|
*/
|
|
nf_ct_seqadj_init(ct, ctinfo, 0);
|
|
synproxy->tsoff = 0;
|
|
this_cpu_inc(snet->stats->conn_reopened);
|
|
fallthrough;
|
|
case TCP_CONNTRACK_SYN_SENT:
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
return NF_DROP;
|
|
|
|
if (!th->syn && th->ack &&
|
|
CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
|
|
/* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
|
|
* therefore we need to add 1 to make the SYN sequence
|
|
* number match the one of first SYN.
|
|
*/
|
|
if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
|
|
ntohl(th->seq) + 1)) {
|
|
this_cpu_inc(snet->stats->cookie_retrans);
|
|
consume_skb(skb);
|
|
return NF_STOLEN;
|
|
} else {
|
|
return NF_DROP;
|
|
}
|
|
}
|
|
|
|
synproxy->isn = ntohl(th->ack_seq);
|
|
if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
|
|
synproxy->its = opts.tsecr;
|
|
|
|
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
|
break;
|
|
case TCP_CONNTRACK_SYN_RECV:
|
|
if (!th->syn || !th->ack)
|
|
break;
|
|
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
return NF_DROP;
|
|
|
|
if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
|
|
synproxy->tsoff = opts.tsval - synproxy->its;
|
|
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
|
}
|
|
|
|
opts.options &= ~(NF_SYNPROXY_OPT_MSS |
|
|
NF_SYNPROXY_OPT_WSCALE |
|
|
NF_SYNPROXY_OPT_SACK_PERM);
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
|
synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
|
|
|
|
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
|
|
nf_conntrack_event_cache(IPCT_SEQADJ, ct);
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
|
synproxy_send_client_ack_ipv6(net, skb, th, &opts);
|
|
|
|
consume_skb(skb);
|
|
return NF_STOLEN;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
|
|
return NF_ACCEPT;
|
|
}
|
|
EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
|
|
|
|
static const struct nf_hook_ops ipv6_synproxy_ops[] = {
|
|
{
|
|
.hook = ipv6_synproxy_hook,
|
|
.pf = NFPROTO_IPV6,
|
|
.hooknum = NF_INET_LOCAL_IN,
|
|
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
|
},
|
|
{
|
|
.hook = ipv6_synproxy_hook,
|
|
.pf = NFPROTO_IPV6,
|
|
.hooknum = NF_INET_POST_ROUTING,
|
|
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
|
},
|
|
};
|
|
|
|
int
|
|
nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
|
|
{
|
|
int err;
|
|
|
|
if (snet->hook_ref6 == 0) {
|
|
err = nf_register_net_hooks(net, ipv6_synproxy_ops,
|
|
ARRAY_SIZE(ipv6_synproxy_ops));
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
snet->hook_ref6++;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
|
|
|
|
void
|
|
nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
|
|
{
|
|
snet->hook_ref6--;
|
|
if (snet->hook_ref6 == 0)
|
|
nf_unregister_net_hooks(net, ipv6_synproxy_ops,
|
|
ARRAY_SIZE(ipv6_synproxy_ops));
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
|
|
#endif /* CONFIG_IPV6 */
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
|
|
MODULE_DESCRIPTION("nftables SYNPROXY expression support");
|