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-rw-r--r--net/ipv6/syncookies.c75
1 files changed, 36 insertions, 39 deletions
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index bf63ac8a49b9..535a3ad262f1 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -24,26 +24,23 @@
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
-/* Table must be sorted. */
+static u32 syncookie6_secret[2][16-4+SHA_DIGEST_WORDS];
+
+/* RFC 2460, Section 8.3:
+ * [ipv6 tcp] MSS must be computed as the maximum packet size minus 60 [..]
+ *
+ * Due to IPV6_MIN_MTU=1280 the lowest possible MSS is 1220, which allows
+ * using higher values than ipv4 tcp syncookies.
+ * The other values are chosen based on ethernet (1500 and 9k MTU), plus
+ * one that accounts for common encap (PPPoe) overhead. Table must be sorted.
+ */
static __u16 const msstab[] = {
- 64,
- 512,
- 536,
- 1280 - 60,
+ 1280 - 60, /* IPV6_MIN_MTU - 60 */
1480 - 60,
1500 - 60,
- 4460 - 60,
9000 - 60,
};
-/*
- * 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
-
static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst)
@@ -66,14 +63,18 @@ static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
static u32 cookie_hash(const struct in6_addr *saddr, const struct in6_addr *daddr,
__be16 sport, __be16 dport, u32 count, int c)
{
- __u32 *tmp = __get_cpu_var(ipv6_cookie_scratch);
+ __u32 *tmp;
+
+ net_get_random_once(syncookie6_secret, sizeof(syncookie6_secret));
+
+ tmp = __get_cpu_var(ipv6_cookie_scratch);
/*
* we have 320 bits of information to hash, copy in the remaining
- * 192 bits required for sha_transform, from the syncookie_secret
+ * 192 bits required for sha_transform, from the syncookie6_secret
* and overwrite the digest with the secret
*/
- memcpy(tmp + 10, syncookie_secret[c], 44);
+ memcpy(tmp + 10, syncookie6_secret[c], 44);
memcpy(tmp, saddr, 16);
memcpy(tmp + 4, daddr, 16);
tmp[8] = ((__force u32)sport << 16) + (__force u32)dport;
@@ -86,8 +87,9 @@ static u32 cookie_hash(const struct in6_addr *saddr, const struct in6_addr *dadd
static __u32 secure_tcp_syn_cookie(const struct in6_addr *saddr,
const struct in6_addr *daddr,
__be16 sport, __be16 dport, __u32 sseq,
- __u32 count, __u32 data)
+ __u32 data)
{
+ u32 count = tcp_cookie_time();
return (cookie_hash(saddr, daddr, sport, dport, 0, 0) +
sseq + (count << COOKIEBITS) +
((cookie_hash(saddr, daddr, sport, dport, count, 1) + data)
@@ -96,15 +98,14 @@ static __u32 secure_tcp_syn_cookie(const struct in6_addr *saddr,
static __u32 check_tcp_syn_cookie(__u32 cookie, const struct in6_addr *saddr,
const struct in6_addr *daddr, __be16 sport,
- __be16 dport, __u32 sseq, __u32 count,
- __u32 maxdiff)
+ __be16 dport, __u32 sseq)
{
- __u32 diff;
+ __u32 diff, count = tcp_cookie_time();
cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq;
diff = (count - (cookie >> COOKIEBITS)) & ((__u32) -1 >> COOKIEBITS);
- if (diff >= maxdiff)
+ if (diff >= MAX_SYNCOOKIE_AGE)
return (__u32)-1;
return (cookie -
@@ -125,8 +126,7 @@ u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
*mssp = msstab[mssind];
return secure_tcp_syn_cookie(&iph->saddr, &iph->daddr, th->source,
- th->dest, ntohl(th->seq),
- jiffies / (HZ * 60), mssind);
+ th->dest, ntohl(th->seq), mssind);
}
EXPORT_SYMBOL_GPL(__cookie_v6_init_sequence);
@@ -146,8 +146,7 @@ int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
{
__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);
+ th->source, th->dest, seq);
return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0;
}
@@ -157,7 +156,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
{
struct tcp_options_received tcp_opt;
struct inet_request_sock *ireq;
- struct inet6_request_sock *ireq6;
struct tcp_request_sock *treq;
struct ipv6_pinfo *np = inet6_sk(sk);
struct tcp_sock *tp = tcp_sk(sk);
@@ -194,7 +192,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
goto out;
ireq = inet_rsk(req);
- ireq6 = inet6_rsk(req);
treq = tcp_rsk(req);
treq->listener = NULL;
@@ -202,22 +199,22 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
goto out_free;
req->mss = mss;
- ireq->rmt_port = th->source;
- ireq->loc_port = th->dest;
- ireq6->rmt_addr = ipv6_hdr(skb)->saddr;
- ireq6->loc_addr = ipv6_hdr(skb)->daddr;
+ ireq->ir_rmt_port = th->source;
+ ireq->ir_num = ntohs(th->dest);
+ ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
+ ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
if (ipv6_opt_accepted(sk, skb) ||
np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
atomic_inc(&skb->users);
- ireq6->pktopts = skb;
+ ireq->pktopts = skb;
}
- ireq6->iif = sk->sk_bound_dev_if;
+ ireq->ir_iif = sk->sk_bound_dev_if;
/* So that link locals have meaning */
if (!sk->sk_bound_dev_if &&
- ipv6_addr_type(&ireq6->rmt_addr) & IPV6_ADDR_LINKLOCAL)
- ireq6->iif = inet6_iif(skb);
+ ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
+ ireq->ir_iif = inet6_iif(skb);
req->expires = 0UL;
req->num_retrans = 0;
@@ -241,12 +238,12 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
struct flowi6 fl6;
memset(&fl6, 0, sizeof(fl6));
fl6.flowi6_proto = IPPROTO_TCP;
- fl6.daddr = ireq6->rmt_addr;
+ fl6.daddr = ireq->ir_v6_rmt_addr;
final_p = fl6_update_dst(&fl6, np->opt, &final);
- fl6.saddr = ireq6->loc_addr;
+ fl6.saddr = ireq->ir_v6_loc_addr;
fl6.flowi6_oif = sk->sk_bound_dev_if;
fl6.flowi6_mark = sk->sk_mark;
- fl6.fl6_dport = inet_rsk(req)->rmt_port;
+ fl6.fl6_dport = ireq->ir_rmt_port;
fl6.fl6_sport = inet_sk(sk)->inet_sport;
security_req_classify_flow(req, flowi6_to_flowi(&fl6));
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.