inet: split syncookie keys for ipv4 and ipv6 and initialize with net_get_random_once

[~andy/linux] / net / ipv4 / syncookies.c

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index b6ea2979a2b721311c30866d56e3693738abd712..b95331e6c077cea0ff215702087fa14acd00abaf 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -25,15 +25,7 @@
 
 extern int sysctl_tcp_syncookies;
 
-__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;
-}
-__initcall(init_syncookies);
+static u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
 
 #define COOKIEBITS 24  /* Upper bits store count */
 #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
@@ -44,8 +36,11 @@ static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
 static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
                       u32 count, int c)
 {
-       __u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
+       __u32 *tmp;
+
+       net_get_random_once(syncookie_secret, sizeof(syncookie_secret));
 
+       tmp  = __get_cpu_var(ipv4_cookie_scratch);
        memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
        tmp[0] = (__force u32)saddr;
        tmp[1] = (__force u32)daddr;
@@ -136,22 +131,22 @@ static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr,
 }
 
 /*
- * MSS Values are taken from the 2009 paper
- * 'Measuring TCP Maximum Segment Size' by S. Alcock and R. Nelson:
- *  - values 1440 to 1460 accounted for 80% of observed mss values
- *  - values outside the 536-1460 range are rare (<0.2%).
+ * MSS Values are chosen based on the 2011 paper
+ * 'An Analysis of TCP Maximum Segement Sizes' by S. Alcock and R. Nelson.
+ * Values ..
+ *  .. lower than 536 are rare (< 0.2%)
+ *  .. between 537 and 1299 account for less than < 1.5% of observed values
+ *  .. in the 1300-1349 range account for about 15 to 20% of observed mss values
+ *  .. exceeding 1460 are very rare (< 0.04%)
  *
- * Table must be sorted.
+ *  1460 is the single most frequently announced mss value (30 to 46% depending
+ *  on monitor location).  Table must be sorted.
  */
 static __u16 const msstab[] = {
-       64,
-       512,
        536,
-       1024,
-       1440,
+       1300,
+       1440,   /* 1440, 1452: PPPoE */
        1460,
-       4312,
-       8960,
 };
 
 /*
@@ -304,10 +299,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
        treq->rcv_isn           = ntohl(th->seq) - 1;
        treq->snt_isn           = cookie;
        req->mss                = mss;
-       ireq->loc_port          = th->dest;
-       ireq->rmt_port          = th->source;
-       ireq->loc_addr          = ip_hdr(skb)->daddr;
-       ireq->rmt_addr          = ip_hdr(skb)->saddr;
+       ireq->ir_num            = ntohs(th->dest);
+       ireq->ir_rmt_port       = th->source;
+       ireq->ir_loc_addr       = ip_hdr(skb)->daddr;
+       ireq->ir_rmt_addr       = ip_hdr(skb)->saddr;
        ireq->ecn_ok            = ecn_ok;
        ireq->snd_wscale        = tcp_opt.snd_wscale;
        ireq->sack_ok           = tcp_opt.sack_ok;
@@ -347,8 +342,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
        flowi4_init_output(&fl4, sk->sk_bound_dev_if, sk->sk_mark,
                           RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, IPPROTO_TCP,
                           inet_sk_flowi_flags(sk),
-                          (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
-                          ireq->loc_addr, th->source, th->dest);
+                          (opt && opt->srr) ? opt->faddr : ireq->ir_rmt_addr,
+                          ireq->ir_loc_addr, th->source, th->dest);
        security_req_classify_flow(req, flowi4_to_flowi(&fl4));
        rt = ip_route_output_key(sock_net(sk), &fl4);
        if (IS_ERR(rt)) {