#include <linux/tcp.h>
#include <linux/slab.h>
#include <linux/random.h>
+#include <linux/cryptohash.h>
#include <linux/kernel.h>
#include <net/tcp.h>
extern int sysctl_tcp_syncookies;
+static __u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
+
+static __init int init_syncookies(void)
+{
+ get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
+ return 0;
+}
+module_init(init_syncookies);
+
+#define COOKIEBITS 24 /* Upper bits store count */
+#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
+
+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] = (__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(__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(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
+ * Where sseq is their sequence number and count increases every
+ * minute by 1.
+ * As an extra hack, we add a small "data" value that encodes the
+ * MSS into the second hash value.
+ */
+
+ return (cookie_hash(saddr, daddr, sport, dport, 0, 0) +
+ sseq + (count << COOKIEBITS) +
+ ((cookie_hash(saddr, daddr, sport, dport, count, 1) + data)
+ & COOKIEMASK));
+}
+
+/*
+ * This retrieves the small "data" value from the syncookie.
+ * If the syncookie is bad, the data returned will be out of
+ * range. This must be checked by the caller.
+ *
+ * The count value used to generate the cookie must be within
+ * "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, __be32 saddr, __be32 daddr,
+ __be16 sport, __be16 dport, __u32 sseq,
+ __u32 count, __u32 maxdiff)
+{
+ __u32 diff;
+
+ /* Strip away the layers from the cookie */
+ cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq;
+
+ /* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
+ diff = (count - (cookie >> COOKIEBITS)) & ((__u32) - 1 >> COOKIEBITS);
+ if (diff >= maxdiff)
+ return (__u32)-1;
+
+ return (cookie -
+ cookie_hash(saddr, daddr, sport, dport, count - diff, 1))
+ & COOKIEMASK; /* Leaving the data behind */
+}
+
/*
* This table has to be sorted and terminated with (__u16)-1.
* XXX generate a better table.
return mssind < NUM_MSS ? msstab[mssind] + 1 : 0;
}
-extern struct or_calltable or_ipv4;
-
static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
- struct open_request *req,
+ struct request_sock *req,
struct dst_entry *dst)
{
- struct tcp_sock *tp = tcp_sk(sk);
+ struct inet_connection_sock *icsk = inet_csk(sk);
struct sock *child;
- child = tp->af_specific->syn_recv_sock(sk, skb, req, dst);
- if (child) {
- sk_set_owner(child, sk->sk_owner);
- tcp_acceptq_queue(sk, req, child);
- } else
- tcp_openreq_free(req);
+ child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
+ if (child)
+ inet_csk_reqsk_queue_add(sk, req, child);
+ else
+ reqsk_free(req);
return child;
}
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt)
{
+ 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;
struct sock *ret = sk;
- struct open_request *req;
+ struct request_sock *req;
int mss;
struct rtable *rt;
__u8 rcv_wscale;
NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESRECV);
- req = tcp_openreq_alloc();
ret = NULL;
+ req = reqsk_alloc(&tcp_request_sock_ops); /* for safety */
if (!req)
goto out;
- req->rcv_isn = htonl(skb->h.th->seq) - 1;
- req->snt_isn = cookie;
+ if (security_inet_conn_request(sk, skb, req)) {
+ reqsk_free(req);
+ goto out;
+ }
+ ireq = inet_rsk(req);
+ treq = tcp_rsk(req);
+ treq->rcv_isn = ntohl(skb->h.th->seq) - 1;
+ treq->snt_isn = cookie;
req->mss = mss;
- req->rmt_port = skb->h.th->source;
- req->af.v4_req.loc_addr = skb->nh.iph->daddr;
- req->af.v4_req.rmt_addr = skb->nh.iph->saddr;
- req->class = &or_ipv4; /* for savety */
- req->af.v4_req.opt = NULL;
+ ireq->rmt_port = skb->h.th->source;
+ ireq->loc_addr = skb->nh.iph->daddr;
+ ireq->rmt_addr = skb->nh.iph->saddr;
+ ireq->opt = NULL;
/* 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)
if (opt && opt->optlen) {
int opt_size = sizeof(struct ip_options) + opt->optlen;
- req->af.v4_req.opt = kmalloc(opt_size, GFP_ATOMIC);
- if (req->af.v4_req.opt) {
- if (ip_options_echo(req->af.v4_req.opt, skb)) {
- kfree(req->af.v4_req.opt);
- req->af.v4_req.opt = NULL;
- }
+ ireq->opt = kmalloc(opt_size, GFP_ATOMIC);
+ if (ireq->opt != NULL && ip_options_echo(ireq->opt, skb)) {
+ kfree(ireq->opt);
+ ireq->opt = NULL;
}
}
- req->snd_wscale = req->rcv_wscale = req->tstamp_ok = 0;
- req->wscale_ok = req->sack_ok = 0;
+ ireq->snd_wscale = ireq->rcv_wscale = ireq->tstamp_ok = 0;
+ ireq->wscale_ok = ireq->sack_ok = 0;
req->expires = 0UL;
req->retrans = 0;
struct flowi fl = { .nl_u = { .ip4_u =
{ .daddr = ((opt && opt->srr) ?
opt->faddr :
- req->af.v4_req.rmt_addr),
- .saddr = req->af.v4_req.loc_addr,
+ ireq->rmt_addr),
+ .saddr = ireq->loc_addr,
.tos = RT_CONN_FLAGS(sk) } },
.proto = IPPROTO_TCP,
.uli_u = { .ports =
{ .sport = skb->h.th->dest,
.dport = skb->h.th->source } } };
+ security_req_classify_flow(req, &fl);
if (ip_route_output_key(&rt, &fl)) {
- tcp_openreq_free(req);
+ reqsk_free(req);
goto out;
}
}
&req->rcv_wnd, &req->window_clamp,
0, &rcv_wscale);
/* BTW win scale with syncookies is 0 by definition */
- req->rcv_wscale = rcv_wscale;
+ ireq->rcv_wscale = rcv_wscale;
ret = get_cookie_sock(sk, skb, req, &rt->u.dst);
out: return ret;
git://git.onelab.eu / linux-2.6.git / blobdiff