0b18fb0798
syn cache overflows. Whether this is due to an attack or due to the system having more legitimate connections than the syn cache can hold, this situation can quickly impact performance. To make the system perform better during these periods, the code will now switch to exclusively using cookies until the syn cache stops overflowing. In order for this to occur, the system must be configured to use the syn cache with syn cookie fallback. If syn cookies are completely disabled, this change should have no functional impact. When the system is exclusively using syn cookies (either due to configuration or the overflow detection enabled by this change), the code will now skip acquiring a lock on the syn cache bucket. Additionally, the code will now skip lookups in several places (such as when the system receives a RST in response to a SYN|ACK frame). Reviewed by: rrs, gallatin (previous version) Discussed with: tuexen Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D21644
148 lines
5.0 KiB
C
148 lines
5.0 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_var.h 8.4 (Berkeley) 5/24/95
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* $FreeBSD$
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*/
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#ifndef _NETINET_TCP_SYNCACHE_H_
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#define _NETINET_TCP_SYNCACHE_H_
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#ifdef _KERNEL
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void syncache_init(void);
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#ifdef VIMAGE
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void syncache_destroy(void);
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#endif
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void syncache_unreach(struct in_conninfo *, tcp_seq);
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int syncache_expand(struct in_conninfo *, struct tcpopt *,
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struct tcphdr *, struct socket **, struct mbuf *);
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int syncache_add(struct in_conninfo *, struct tcpopt *,
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struct tcphdr *, struct inpcb *, struct socket **, struct mbuf *,
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void *, void *);
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void syncache_chkrst(struct in_conninfo *, struct tcphdr *, struct mbuf *);
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void syncache_badack(struct in_conninfo *);
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int syncache_pcblist(struct sysctl_req *req, int max_pcbs, int *pcbs_exported);
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struct syncache {
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TAILQ_ENTRY(syncache) sc_hash;
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struct in_conninfo sc_inc; /* addresses */
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int sc_rxttime; /* retransmit time */
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u_int16_t sc_rxmits; /* retransmit counter */
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u_int32_t sc_tsreflect; /* timestamp to reflect */
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u_int32_t sc_tsoff; /* ts offset w/ syncookies */
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u_int32_t sc_flowlabel; /* IPv6 flowlabel */
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tcp_seq sc_irs; /* seq from peer */
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tcp_seq sc_iss; /* our ISS */
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struct mbuf *sc_ipopts; /* source route */
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u_int16_t sc_peer_mss; /* peer's MSS */
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u_int16_t sc_wnd; /* advertised window */
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u_int8_t sc_ip_ttl; /* IPv4 TTL */
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u_int8_t sc_ip_tos; /* IPv4 TOS */
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u_int8_t sc_requested_s_scale:4,
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sc_requested_r_scale:4;
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u_int16_t sc_flags;
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#if defined(TCP_OFFLOAD) || !defined(TCP_OFFLOAD_DISABLE)
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struct toedev *sc_tod; /* entry added by this TOE */
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void *sc_todctx; /* TOE driver context */
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#endif
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struct label *sc_label; /* MAC label reference */
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struct ucred *sc_cred; /* cred cache for jail checks */
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void *sc_tfo_cookie; /* for TCP Fast Open response */
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void *sc_pspare; /* TCP_SIGNATURE */
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u_int32_t sc_spare[2]; /* UTO */
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};
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/*
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* Flags for the sc_flags field.
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*/
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#define SCF_NOOPT 0x01 /* no TCP options */
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#define SCF_WINSCALE 0x02 /* negotiated window scaling */
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#define SCF_TIMESTAMP 0x04 /* negotiated timestamps */
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/* MSS is implicit */
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#define SCF_UNREACH 0x10 /* icmp unreachable received */
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#define SCF_SIGNATURE 0x20 /* send MD5 digests */
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#define SCF_SACK 0x80 /* send SACK option */
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#define SCF_ECN 0x100 /* send ECN setup packet */
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struct syncache_head {
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struct mtx sch_mtx;
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TAILQ_HEAD(sch_head, syncache) sch_bucket;
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struct callout sch_timer;
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int sch_nextc;
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u_int sch_length;
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struct tcp_syncache *sch_sc;
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time_t sch_last_overflow;
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};
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#define SYNCOOKIE_SECRET_SIZE 16
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#define SYNCOOKIE_LIFETIME 15 /* seconds */
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struct syncookie_secret {
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volatile u_int oddeven;
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uint8_t key[2][SYNCOOKIE_SECRET_SIZE];
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struct callout reseed;
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u_int lifetime;
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};
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#define TCP_SYNCACHE_PAUSE_TIME SYNCOOKIE_LIFETIME
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#define TCP_SYNCACHE_MAX_BACKOFF 6 /* 16 minutes */
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struct tcp_syncache {
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struct syncache_head *hashbase;
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uma_zone_t zone;
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u_int hashsize;
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u_int hashmask;
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u_int bucket_limit;
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u_int cache_limit;
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u_int rexmt_limit;
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uint32_t hash_secret;
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struct vnet *vnet;
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struct syncookie_secret secret;
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struct mtx pause_mtx;
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struct callout pause_co;
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time_t pause_until;
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uint8_t pause_backoff;
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volatile bool paused;
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};
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/* Internal use for the syncookie functions. */
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union syncookie {
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uint8_t cookie;
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struct {
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uint8_t odd_even:1,
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sack_ok:1,
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wscale_idx:3,
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mss_idx:3;
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} flags;
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};
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#endif /* _KERNEL */
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#endif /* !_NETINET_TCP_SYNCACHE_H_ */
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