mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 06:36:42 +07:00
0144a81ccc
ss should display ipv4 mapped request sockets like this :
tcp SYN-RECV 0 0 ::ffff:192.168.0.1:8080 ::ffff:192.0.2.1:35261
and not like this :
tcp SYN-RECV 0 0 192.168.0.1:8080 192.0.2.1:35261
We should init ireq->ireq_family based on listener sk_family,
not the actual protocol carried by SYN packet.
This means we can set ireq_family in inet_reqsk_alloc()
Fixes: 3f66b083a5
("inet: introduce ireq_family")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
402 lines
11 KiB
C
402 lines
11 KiB
C
/*
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* Syncookies implementation for the Linux kernel
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*
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* Copyright (C) 1997 Andi Kleen
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* Based on ideas by D.J.Bernstein and Eric Schenk.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/tcp.h>
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#include <linux/slab.h>
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#include <linux/random.h>
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#include <linux/cryptohash.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <net/tcp.h>
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#include <net/route.h>
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extern int sysctl_tcp_syncookies;
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static u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS] __read_mostly;
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#define COOKIEBITS 24 /* Upper bits store count */
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#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
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/* TCP Timestamp: 6 lowest bits of timestamp sent in the cookie SYN-ACK
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* stores TCP options:
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*
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* MSB LSB
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* | 31 ... 6 | 5 | 4 | 3 2 1 0 |
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* | Timestamp | ECN | SACK | WScale |
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*
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* When we receive a valid cookie-ACK, we look at the echoed tsval (if
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* any) to figure out which TCP options we should use for the rebuilt
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* connection.
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*
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* A WScale setting of '0xf' (which is an invalid scaling value)
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* means that original syn did not include the TCP window scaling option.
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*/
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#define TS_OPT_WSCALE_MASK 0xf
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#define TS_OPT_SACK BIT(4)
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#define TS_OPT_ECN BIT(5)
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/* There is no TS_OPT_TIMESTAMP:
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* if ACK contains timestamp option, we already know it was
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* requested/supported by the syn/synack exchange.
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*/
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#define TSBITS 6
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#define TSMASK (((__u32)1 << TSBITS) - 1)
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static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
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ipv4_cookie_scratch);
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static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
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u32 count, int c)
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{
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__u32 *tmp;
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net_get_random_once(syncookie_secret, sizeof(syncookie_secret));
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tmp = this_cpu_ptr(ipv4_cookie_scratch);
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memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
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tmp[0] = (__force u32)saddr;
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tmp[1] = (__force u32)daddr;
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tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
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tmp[3] = count;
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sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5);
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return tmp[17];
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}
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/*
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* when syncookies are in effect and tcp timestamps are enabled we encode
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* tcp options in the lower bits of the timestamp value that will be
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* sent in the syn-ack.
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* Since subsequent timestamps use the normal tcp_time_stamp value, we
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* must make sure that the resulting initial timestamp is <= tcp_time_stamp.
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*/
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__u32 cookie_init_timestamp(struct request_sock *req)
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{
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struct inet_request_sock *ireq;
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u32 ts, ts_now = tcp_time_stamp;
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u32 options = 0;
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ireq = inet_rsk(req);
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options = ireq->wscale_ok ? ireq->snd_wscale : TS_OPT_WSCALE_MASK;
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if (ireq->sack_ok)
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options |= TS_OPT_SACK;
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if (ireq->ecn_ok)
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options |= TS_OPT_ECN;
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ts = ts_now & ~TSMASK;
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ts |= options;
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if (ts > ts_now) {
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ts >>= TSBITS;
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ts--;
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ts <<= TSBITS;
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ts |= options;
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}
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return ts;
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}
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static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport,
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__be16 dport, __u32 sseq, __u32 data)
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{
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/*
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* Compute the secure sequence number.
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* The output should be:
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* HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
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* + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
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* Where sseq is their sequence number and count increases every
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* minute by 1.
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* As an extra hack, we add a small "data" value that encodes the
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* MSS into the second hash value.
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*/
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u32 count = tcp_cookie_time();
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return (cookie_hash(saddr, daddr, sport, dport, 0, 0) +
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sseq + (count << COOKIEBITS) +
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((cookie_hash(saddr, daddr, sport, dport, count, 1) + data)
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& COOKIEMASK));
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}
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/*
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* This retrieves the small "data" value from the syncookie.
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* If the syncookie is bad, the data returned will be out of
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* range. This must be checked by the caller.
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*
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* The count value used to generate the cookie must be less than
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* MAX_SYNCOOKIE_AGE minutes in the past.
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* The return value (__u32)-1 if this test fails.
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*/
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static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr,
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__be16 sport, __be16 dport, __u32 sseq)
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{
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u32 diff, count = tcp_cookie_time();
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/* Strip away the layers from the cookie */
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cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq;
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/* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
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diff = (count - (cookie >> COOKIEBITS)) & ((__u32) -1 >> COOKIEBITS);
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if (diff >= MAX_SYNCOOKIE_AGE)
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return (__u32)-1;
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return (cookie -
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cookie_hash(saddr, daddr, sport, dport, count - diff, 1))
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& COOKIEMASK; /* Leaving the data behind */
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}
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/*
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* MSS Values are chosen based on the 2011 paper
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* 'An Analysis of TCP Maximum Segement Sizes' by S. Alcock and R. Nelson.
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* Values ..
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* .. lower than 536 are rare (< 0.2%)
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* .. between 537 and 1299 account for less than < 1.5% of observed values
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* .. in the 1300-1349 range account for about 15 to 20% of observed mss values
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* .. exceeding 1460 are very rare (< 0.04%)
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*
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* 1460 is the single most frequently announced mss value (30 to 46% depending
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* on monitor location). Table must be sorted.
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*/
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static __u16 const msstab[] = {
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536,
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1300,
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1440, /* 1440, 1452: PPPoE */
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1460,
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};
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/*
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* Generate a syncookie. mssp points to the mss, which is returned
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* rounded down to the value encoded in the cookie.
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*/
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u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
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u16 *mssp)
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{
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int mssind;
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const __u16 mss = *mssp;
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for (mssind = ARRAY_SIZE(msstab) - 1; mssind ; mssind--)
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if (mss >= msstab[mssind])
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break;
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*mssp = msstab[mssind];
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return secure_tcp_syn_cookie(iph->saddr, iph->daddr,
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th->source, th->dest, ntohl(th->seq),
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mssind);
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}
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EXPORT_SYMBOL_GPL(__cookie_v4_init_sequence);
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__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
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__u16 *mssp)
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{
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const struct iphdr *iph = ip_hdr(skb);
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const struct tcphdr *th = tcp_hdr(skb);
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tcp_synq_overflow(sk);
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NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
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return __cookie_v4_init_sequence(iph, th, mssp);
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}
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/*
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* Check if a ack sequence number is a valid syncookie.
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* Return the decoded mss if it is, or 0 if not.
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*/
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int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th,
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u32 cookie)
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{
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__u32 seq = ntohl(th->seq) - 1;
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__u32 mssind = check_tcp_syn_cookie(cookie, iph->saddr, iph->daddr,
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th->source, th->dest, seq);
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return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0;
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}
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EXPORT_SYMBOL_GPL(__cookie_v4_check);
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static struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
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struct request_sock *req,
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struct dst_entry *dst)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct sock *child;
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child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
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if (child) {
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atomic_set(&req->rsk_refcnt, 1);
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inet_csk_reqsk_queue_add(sk, req, child);
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} else {
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reqsk_free(req);
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}
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return child;
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}
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/*
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* when syncookies are in effect and tcp timestamps are enabled we stored
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* additional tcp options in the timestamp.
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* This extracts these options from the timestamp echo.
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*
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* return false if we decode a tcp option that is disabled
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* on the host.
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*/
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bool cookie_timestamp_decode(struct tcp_options_received *tcp_opt)
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{
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/* echoed timestamp, lowest bits contain options */
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u32 options = tcp_opt->rcv_tsecr;
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if (!tcp_opt->saw_tstamp) {
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tcp_clear_options(tcp_opt);
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return true;
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}
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if (!sysctl_tcp_timestamps)
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return false;
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tcp_opt->sack_ok = (options & TS_OPT_SACK) ? TCP_SACK_SEEN : 0;
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if (tcp_opt->sack_ok && !sysctl_tcp_sack)
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return false;
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if ((options & TS_OPT_WSCALE_MASK) == TS_OPT_WSCALE_MASK)
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return true; /* no window scaling */
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tcp_opt->wscale_ok = 1;
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tcp_opt->snd_wscale = options & TS_OPT_WSCALE_MASK;
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return sysctl_tcp_window_scaling != 0;
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}
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EXPORT_SYMBOL(cookie_timestamp_decode);
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bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt,
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const struct net *net, const struct dst_entry *dst)
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{
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bool ecn_ok = tcp_opt->rcv_tsecr & TS_OPT_ECN;
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if (!ecn_ok)
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return false;
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if (net->ipv4.sysctl_tcp_ecn)
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return true;
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return dst_feature(dst, RTAX_FEATURE_ECN);
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}
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EXPORT_SYMBOL(cookie_ecn_ok);
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struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
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{
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struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
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struct tcp_options_received tcp_opt;
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struct inet_request_sock *ireq;
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struct tcp_request_sock *treq;
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struct tcp_sock *tp = tcp_sk(sk);
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const struct tcphdr *th = tcp_hdr(skb);
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__u32 cookie = ntohl(th->ack_seq) - 1;
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struct sock *ret = sk;
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struct request_sock *req;
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int mss;
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struct rtable *rt;
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__u8 rcv_wscale;
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struct flowi4 fl4;
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if (!sysctl_tcp_syncookies || !th->ack || th->rst)
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goto out;
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if (tcp_synq_no_recent_overflow(sk))
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goto out;
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mss = __cookie_v4_check(ip_hdr(skb), th, cookie);
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if (mss == 0) {
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NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
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goto out;
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}
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NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESRECV);
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/* check for timestamp cookie support */
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memset(&tcp_opt, 0, sizeof(tcp_opt));
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tcp_parse_options(skb, &tcp_opt, 0, NULL);
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if (!cookie_timestamp_decode(&tcp_opt))
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goto out;
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ret = NULL;
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req = inet_reqsk_alloc(&tcp_request_sock_ops, sk); /* for safety */
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if (!req)
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goto out;
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ireq = inet_rsk(req);
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treq = tcp_rsk(req);
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treq->rcv_isn = ntohl(th->seq) - 1;
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treq->snt_isn = cookie;
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req->mss = mss;
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ireq->ir_num = ntohs(th->dest);
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ireq->ir_rmt_port = th->source;
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sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
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sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
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ireq->ir_mark = inet_request_mark(sk, skb);
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ireq->snd_wscale = tcp_opt.snd_wscale;
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ireq->sack_ok = tcp_opt.sack_ok;
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ireq->wscale_ok = tcp_opt.wscale_ok;
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ireq->tstamp_ok = tcp_opt.saw_tstamp;
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req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;
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treq->snt_synack = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsecr : 0;
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treq->tfo_listener = false;
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ireq->ir_iif = sk->sk_bound_dev_if;
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/* We throwed the options of the initial SYN away, so we hope
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* the ACK carries the same options again (see RFC1122 4.2.3.8)
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*/
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ireq->opt = tcp_v4_save_options(skb);
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if (security_inet_conn_request(sk, skb, req)) {
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reqsk_free(req);
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goto out;
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}
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req->num_retrans = 0;
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/*
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* We need to lookup the route here to get at the correct
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* window size. We should better make sure that the window size
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* hasn't changed since we received the original syn, but I see
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* no easy way to do this.
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*/
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flowi4_init_output(&fl4, sk->sk_bound_dev_if, ireq->ir_mark,
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RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, IPPROTO_TCP,
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inet_sk_flowi_flags(sk),
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opt->srr ? opt->faddr : ireq->ir_rmt_addr,
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ireq->ir_loc_addr, th->source, th->dest);
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security_req_classify_flow(req, flowi4_to_flowi(&fl4));
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rt = ip_route_output_key(sock_net(sk), &fl4);
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if (IS_ERR(rt)) {
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reqsk_free(req);
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goto out;
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}
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/* Try to redo what tcp_v4_send_synack did. */
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req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
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tcp_select_initial_window(tcp_full_space(sk), req->mss,
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&req->rcv_wnd, &req->window_clamp,
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ireq->wscale_ok, &rcv_wscale,
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dst_metric(&rt->dst, RTAX_INITRWND));
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ireq->rcv_wscale = rcv_wscale;
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ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, sock_net(sk), &rt->dst);
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ret = get_cookie_sock(sk, skb, req, &rt->dst);
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/* ip_queue_xmit() depends on our flow being setup
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* Normal sockets get it right from inet_csk_route_child_sock()
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*/
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if (ret)
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inet_sk(ret)->cork.fl.u.ip4 = fl4;
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out: return ret;
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}
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