* 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.
*/
#include <linux/tcp.h>
#include <linux/kernel.h>
#include <net/tcp.h>
+/* Timestamps: lowest 9 bits store TCP options */
+#define TSBITS 9
+#define TSMASK (((__u32)1 << TSBITS) - 1)
+
extern int sysctl_tcp_syncookies;
-static __u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
+__u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
+EXPORT_SYMBOL(syncookie_secret);
static __init int init_syncookies(void)
{
get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
return 0;
}
-module_init(init_syncookies);
+__initcall(init_syncookies);
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
+static DEFINE_PER_CPU(__u32, cookie_scratch)[16 + 5 + SHA_WORKSPACE_WORDS];
+
static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
u32 count, int c)
{
- __u32 tmp[16 + 5 + SHA_WORKSPACE_WORDS];
+ __u32 *tmp = __get_cpu_var(cookie_scratch);
- memcpy(tmp + 3, syncookie_secret[c], sizeof(syncookie_secret[c]));
+ memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
tmp[0] = (__force u32)saddr;
tmp[1] = (__force u32)daddr;
tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
return tmp[17];
}
+
+/*
+ * when syncookies are in effect and tcp timestamps are enabled we encode
+ * tcp options in the lowest 9 bits of the timestamp value that will be
+ * sent in the syn-ack.
+ * Since subsequent timestamps use the normal tcp_time_stamp value, we
+ * must make sure that the resulting initial timestamp is <= tcp_time_stamp.
+ */
+__u32 cookie_init_timestamp(struct request_sock *req)
+{
+ struct inet_request_sock *ireq;
+ u32 ts, ts_now = tcp_time_stamp;
+ u32 options = 0;
+
+ ireq = inet_rsk(req);
+ if (ireq->wscale_ok) {
+ options = ireq->snd_wscale;
+ options |= ireq->rcv_wscale << 4;
+ }
+ options |= ireq->sack_ok << 8;
+
+ ts = ts_now & ~TSMASK;
+ ts |= options;
+ if (ts > ts_now) {
+ ts >>= TSBITS;
+ ts--;
+ ts <<= TSBITS;
+ ts |= options;
+ }
+ return ts;
+}
+
+
static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport,
__be16 dport, __u32 sseq, __u32 count,
__u32 data)
;
*mssp = msstab[mssind] + 1;
- NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESSENT);
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
return secure_tcp_syn_cookie(iph->saddr, iph->daddr,
th->source, th->dest, ntohl(th->seq),
return child;
}
+
+/*
+ * when syncookies are in effect and tcp timestamps are enabled we stored
+ * additional tcp options in the timestamp.
+ * This extracts these options from the timestamp echo.
+ *
+ * The lowest 4 bits are for snd_wscale
+ * The next 4 lsb are for rcv_wscale
+ * The next lsb is for sack_ok
+ */
+void cookie_check_timestamp(struct tcp_options_received *tcp_opt)
+{
+ /* echoed timestamp, 9 lowest bits contain options */
+ u32 options = tcp_opt->rcv_tsecr & TSMASK;
+
+ tcp_opt->snd_wscale = options & 0xf;
+ options >>= 4;
+ tcp_opt->rcv_wscale = options & 0xf;
+
+ tcp_opt->sack_ok = (options >> 4) & 0x1;
+
+ if (tcp_opt->sack_ok)
+ tcp_sack_reset(tcp_opt);
+
+ if (tcp_opt->snd_wscale || tcp_opt->rcv_wscale)
+ tcp_opt->wscale_ok = 1;
+}
+EXPORT_SYMBOL(cookie_check_timestamp);
+
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt)
{
int mss;
struct rtable *rt;
__u8 rcv_wscale;
+ struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
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(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
goto out;
}
- NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESRECV);
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESRECV);
+
+ /* check for timestamp cookie support */
+ memset(&tcp_opt, 0, sizeof(tcp_opt));
+ tcp_parse_options(skb, &tcp_opt, 0);
+
+ if (tcp_opt.saw_tstamp)
+ cookie_check_timestamp(&tcp_opt);
ret = NULL;
- req = reqsk_alloc(&tcp_request_sock_ops); /* for safety */
+ req = inet_reqsk_alloc(&tcp_request_sock_ops); /* for safety */
if (!req)
goto out;
ireq->rmt_port = th->source;
ireq->loc_addr = ip_hdr(skb)->daddr;
ireq->rmt_addr = ip_hdr(skb)->saddr;
- ireq->opt = NULL;
+ ireq->snd_wscale = tcp_opt.snd_wscale;
+ ireq->rcv_wscale = tcp_opt.rcv_wscale;
+ ireq->sack_ok = tcp_opt.sack_ok;
+ ireq->wscale_ok = tcp_opt.wscale_ok;
+ ireq->tstamp_ok = tcp_opt.saw_tstamp;
+ req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;
/* We throwed the options of the initial SYN away, so we hope
* the ACK carries the same options again (see RFC1122 4.2.3.8)
}
}
- ireq->snd_wscale = ireq->rcv_wscale = ireq->tstamp_ok = 0;
- ireq->wscale_ok = ireq->sack_ok = 0;
req->expires = 0UL;
req->retrans = 0;
}
/* Try to redo what tcp_v4_send_synack did. */
- req->window_clamp = dst_metric(&rt->u.dst, RTAX_WINDOW);
+ req->window_clamp = tp->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,
- 0, &rcv_wscale);
- /* BTW win scale with syncookies is 0 by definition */
+ ireq->wscale_ok, &rcv_wscale);
+
ireq->rcv_wscale = rcv_wscale;
ret = get_cookie_sock(sk, skb, req, &rt->u.dst);
git.openpandora.org / pandora-kernel.git / blobdiff