X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=net%2Fipv4%2Fsyncookies.c;h=2da1be0589a9e7f2fb2cb6c0383e0452df570207;hb=95b00786f3b8fa99f53931361beeb4c10504ad87;hp=661e0a4bca72dbc7a81df0de71313c38b2a2559f;hpb=cdb8355add9b1d87ecfcb58b12879897dc1e3e36;p=linux-2.6 diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 661e0a4bca..2da1be0589 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -2,16 +2,16 @@ * Syncookies implementation for the Linux kernel * * Copyright (C) 1997 Andi Kleen - * Based on ideas by D.J.Bernstein and Eric Schenk. + * Based on ideas by D.J.Bernstein and Eric Schenk. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. - * + * * $Id: syncookies.c,v 1.18 2002/02/01 22:01:04 davem Exp $ * - * Missing: IPv6 support. + * Missing: IPv6 support. */ #include @@ -35,29 +35,29 @@ module_init(init_syncookies); #define COOKIEBITS 24 /* Upper bits store count */ #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1) -static u32 cookie_hash(u32 saddr, u32 daddr, u32 sport, u32 dport, +static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport, u32 count, int c) { __u32 tmp[16 + 5 + SHA_WORKSPACE_WORDS]; memcpy(tmp + 3, syncookie_secret[c], sizeof(syncookie_secret[c])); - tmp[0] = saddr; - tmp[1] = daddr; - tmp[2] = (sport << 16) + dport; + tmp[0] = (__force u32)saddr; + tmp[1] = (__force u32)daddr; + tmp[2] = ((__force u32)sport << 16) + (__force u32)dport; tmp[3] = count; sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5); return tmp[17]; } -static __u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr, __u16 sport, - __u16 dport, __u32 sseq, __u32 count, +static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport, + __be16 dport, __u32 sseq, __u32 count, __u32 data) { /* * Compute the secure sequence number. * The output should be: - * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24) + * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24) * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24). * Where sseq is their sequence number and count increases every * minute by 1. @@ -80,8 +80,8 @@ static __u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr, __u16 sport, * "maxdiff" if the current (passed-in) "count". The return value * is (__u32)-1 if this test fails. */ -static __u32 check_tcp_syn_cookie(__u32 cookie, __u32 saddr, __u32 daddr, - __u16 sport, __u16 dport, __u32 sseq, +static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr, + __be16 sport, __be16 dport, __u32 sseq, __u32 count, __u32 maxdiff) { __u32 diff; @@ -99,17 +99,17 @@ static __u32 check_tcp_syn_cookie(__u32 cookie, __u32 saddr, __u32 daddr, & COOKIEMASK; /* Leaving the data behind */ } -/* +/* * This table has to be sorted and terminated with (__u16)-1. * XXX generate a better table. * Unresolved Issues: HIPPI with a 64k MSS is not well supported. */ static __u16 const msstab[] = { 64 - 1, - 256 - 1, + 256 - 1, 512 - 1, 536 - 1, - 1024 - 1, + 1024 - 1, 1440 - 1, 1460 - 1, 4312 - 1, @@ -125,10 +125,11 @@ static __u16 const msstab[] = { __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp) { struct tcp_sock *tp = tcp_sk(sk); + const struct iphdr *iph = ip_hdr(skb); + const struct tcphdr *th = tcp_hdr(skb); int mssind; const __u16 mss = *mssp; - tp->last_synq_overflow = jiffies; /* XXX sort msstab[] by probability? Binary search? */ @@ -138,33 +139,31 @@ __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp) NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESSENT); - return secure_tcp_syn_cookie(skb->nh.iph->saddr, skb->nh.iph->daddr, - skb->h.th->source, skb->h.th->dest, - ntohl(skb->h.th->seq), + return secure_tcp_syn_cookie(iph->saddr, iph->daddr, + th->source, th->dest, ntohl(th->seq), jiffies / (HZ * 60), mssind); } -/* +/* * This (misnamed) value is the age of syncookie which is permitted. * Its ideal value should be dependent on TCP_TIMEOUT_INIT and * sysctl_tcp_retries1. It's a rather complicated formula (exponential * backoff) to compute at runtime so it's currently hardcoded here. */ #define COUNTER_TRIES 4 -/* - * Check if a ack sequence number is a valid syncookie. +/* + * Check if a ack sequence number is a valid syncookie. * Return the decoded mss if it is, or 0 if not. */ static inline int cookie_check(struct sk_buff *skb, __u32 cookie) { - __u32 seq; - __u32 mssind; - - seq = ntohl(skb->h.th->seq)-1; - mssind = check_tcp_syn_cookie(cookie, - skb->nh.iph->saddr, skb->nh.iph->daddr, - skb->h.th->source, skb->h.th->dest, - seq, jiffies / (HZ * 60), COUNTER_TRIES); + const struct iphdr *iph = ip_hdr(skb); + const struct tcphdr *th = tcp_hdr(skb); + __u32 seq = ntohl(th->seq) - 1; + __u32 mssind = check_tcp_syn_cookie(cookie, iph->saddr, iph->daddr, + th->source, th->dest, seq, + jiffies / (HZ * 60), + COUNTER_TRIES); return mssind < NUM_MSS ? msstab[mssind] + 1 : 0; } @@ -191,19 +190,20 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, struct inet_request_sock *ireq; struct tcp_request_sock *treq; struct tcp_sock *tp = tcp_sk(sk); - __u32 cookie = ntohl(skb->h.th->ack_seq) - 1; + const struct tcphdr *th = tcp_hdr(skb); + __u32 cookie = ntohl(th->ack_seq) - 1; struct sock *ret = sk; - struct request_sock *req; - int mss; - struct rtable *rt; + struct request_sock *req; + int mss; + struct rtable *rt; __u8 rcv_wscale; - if (!sysctl_tcp_syncookies || !skb->h.th->ack) + if (!sysctl_tcp_syncookies || !th->ack) goto out; - if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) || + if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) || (mss = cookie_check(skb, cookie)) == 0) { - NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESFAILED); + NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESFAILED); goto out; } @@ -220,12 +220,12 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, } ireq = inet_rsk(req); treq = tcp_rsk(req); - treq->rcv_isn = htonl(skb->h.th->seq) - 1; - treq->snt_isn = cookie; + treq->rcv_isn = ntohl(th->seq) - 1; + treq->snt_isn = cookie; req->mss = mss; - ireq->rmt_port = skb->h.th->source; - ireq->loc_addr = skb->nh.iph->daddr; - ireq->rmt_addr = skb->nh.iph->saddr; + ireq->rmt_port = th->source; + ireq->loc_addr = ip_hdr(skb)->daddr; + ireq->rmt_addr = ip_hdr(skb)->saddr; ireq->opt = NULL; /* We throwed the options of the initial SYN away, so we hope @@ -242,15 +242,15 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, } ireq->snd_wscale = ireq->rcv_wscale = ireq->tstamp_ok = 0; - ireq->wscale_ok = ireq->sack_ok = 0; - req->expires = 0UL; - req->retrans = 0; - + ireq->wscale_ok = ireq->sack_ok = 0; + req->expires = 0UL; + req->retrans = 0; + /* * We need to lookup the route here to get at the correct * window size. We should better make sure that the window size * hasn't changed since we received the original syn, but I see - * no easy way to do this. + * no easy way to do this. */ { struct flowi fl = { .nl_u = { .ip4_u = @@ -261,22 +261,22 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, .tos = RT_CONN_FLAGS(sk) } }, .proto = IPPROTO_TCP, .uli_u = { .ports = - { .sport = skb->h.th->dest, - .dport = skb->h.th->source } } }; + { .sport = th->dest, + .dport = th->source } } }; security_req_classify_flow(req, &fl); if (ip_route_output_key(&rt, &fl)) { reqsk_free(req); - goto out; + goto out; } } /* Try to redo what tcp_v4_send_synack did. */ req->window_clamp = dst_metric(&rt->u.dst, RTAX_WINDOW); tcp_select_initial_window(tcp_full_space(sk), req->mss, - &req->rcv_wnd, &req->window_clamp, + &req->rcv_wnd, &req->window_clamp, 0, &rcv_wscale); /* BTW win scale with syncookies is 0 by definition */ - ireq->rcv_wscale = rcv_wscale; + ireq->rcv_wscale = rcv_wscale; ret = get_cookie_sock(sk, skb, req, &rt->u.dst); out: return ret;