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Message-id: <20180201000716.69301-10-cpaasch@apple.com>
Date: Wed, 31 Jan 2018 16:07:11 -0800
From: Christoph Paasch <cpaasch@...le.com>
To: netdev@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>,
Mat Martineau <mathew.j.martineau@...ux.intel.com>,
Ivan Delalande <colona@...sta.com>
Subject: [RFC v2 09/14] tcp_md5: Detect key inside tcp_v6_send_response instead
of passing it as an argument
We want to move all the TCP-MD5 code to a single place which enables us
to factor the TCP-MD5 code out of the TCP-stack into the extra-option
framework.
Detection of whether or not to drop the segment (as done in
tcp_v6_send_reset()) has now been moved to tcp_v6_send_response().
So we needed to adapt the latter so that it can handle the case where we
want to exit without sending anything.
Cc: Ivan Delalande <colona@...sta.com>
Signed-off-by: Christoph Paasch <cpaasch@...le.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
net/ipv6/tcp_ipv6.c | 119 +++++++++++++++++++++++++---------------------------
1 file changed, 57 insertions(+), 62 deletions(-)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 202bf011f462..8c6d0362299e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -82,12 +82,6 @@ static const struct inet_connection_sock_af_ops ipv6_specific;
#ifdef CONFIG_TCP_MD5SIG
static const struct tcp_sock_af_ops tcp_sock_ipv6_specific;
static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
-#else
-static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
- const struct in6_addr *addr)
-{
- return NULL;
-}
#endif
static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
@@ -779,12 +773,11 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 seq,
u32 ack, u32 win, u32 tsval, u32 tsecr,
- int oif, struct tcp_md5sig_key *key, int rst,
- u8 tclass, __be32 label)
+ int oif, int rst, u8 tclass, __be32 label)
{
const struct tcphdr *th = tcp_hdr(skb);
struct tcphdr *t1;
- struct sk_buff *buff;
+ struct sk_buff *buff = NULL;
struct flowi6 fl6;
struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
struct sock *ctl_sk = net->ipv6.tcp_sk;
@@ -793,10 +786,54 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
__be32 *topt;
struct hlist_head *extopt_list = NULL;
struct tcp_out_options extraopts;
+#ifdef CONFIG_TCP_MD5SIG
+ struct tcp_md5sig_key *key = NULL;
+ const __u8 *hash_location = NULL;
+ struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+#endif
if (tsecr)
tot_len += TCPOLEN_TSTAMP_ALIGNED;
#ifdef CONFIG_TCP_MD5SIG
+ rcu_read_lock();
+ hash_location = tcp_parse_md5sig_option(th);
+ if (sk && sk_fullsock(sk)) {
+ key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr);
+ } else if (sk && sk->sk_state == TCP_TIME_WAIT) {
+ struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+
+ key = tcp_twsk_md5_key(tcptw);
+ } else if (sk && sk->sk_state == TCP_NEW_SYN_RECV) {
+ key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr);
+ } else if (hash_location) {
+ unsigned char newhash[16];
+ struct sock *sk1 = NULL;
+ int genhash;
+
+ /* active side is lost. Try to find listening socket through
+ * source port, and then find md5 key through listening socket.
+ * we are not loose security here:
+ * Incoming packet is checked with md5 hash with finding key,
+ * no RST generated if md5 hash doesn't match.
+ */
+ sk1 = inet6_lookup_listener(dev_net(skb_dst(skb)->dev),
+ &tcp_hashinfo, NULL, 0,
+ &ipv6h->saddr,
+ th->source, &ipv6h->daddr,
+ ntohs(th->source), tcp_v6_iif(skb),
+ tcp_v6_sdif(skb));
+ if (!sk1)
+ goto out;
+
+ key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr);
+ if (!key)
+ goto out;
+
+ genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
+ if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ goto out;
+ }
+
if (key)
tot_len += TCPOLEN_MD5SIG_ALIGNED;
#endif
@@ -823,7 +860,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
GFP_ATOMIC);
if (!buff)
- return;
+ goto out;
skb_reserve(buff, MAX_HEADER + sizeof(struct ipv6hdr) + tot_len);
@@ -900,24 +937,21 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
if (rst)
TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
- return;
+ buff = NULL;
}
+out:
kfree_skb(buff);
+
+#ifdef CONFIG_TCP_MD5SIG
+ rcu_read_unlock();
+#endif
}
static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
{
const struct tcphdr *th = tcp_hdr(skb);
u32 seq = 0, ack_seq = 0;
- struct tcp_md5sig_key *key = NULL;
-#ifdef CONFIG_TCP_MD5SIG
- const __u8 *hash_location = NULL;
- struct ipv6hdr *ipv6h = ipv6_hdr(skb);
- unsigned char newhash[16];
- int genhash;
- struct sock *sk1 = NULL;
-#endif
int oif = 0;
if (th->rst)
@@ -929,38 +963,6 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
if (!sk && !ipv6_unicast_destination(skb))
return;
-#ifdef CONFIG_TCP_MD5SIG
- rcu_read_lock();
- hash_location = tcp_parse_md5sig_option(th);
- if (sk && sk_fullsock(sk)) {
- key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr);
- } else if (hash_location) {
- /*
- * active side is lost. Try to find listening socket through
- * source port, and then find md5 key through listening socket.
- * we are not loose security here:
- * Incoming packet is checked with md5 hash with finding key,
- * no RST generated if md5 hash doesn't match.
- */
- sk1 = inet6_lookup_listener(dev_net(skb_dst(skb)->dev),
- &tcp_hashinfo, NULL, 0,
- &ipv6h->saddr,
- th->source, &ipv6h->daddr,
- ntohs(th->source), tcp_v6_iif(skb),
- tcp_v6_sdif(skb));
- if (!sk1)
- goto out;
-
- key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr);
- if (!key)
- goto out;
-
- genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
- if (genhash || memcmp(hash_location, newhash, 16) != 0)
- goto out;
- }
-#endif
-
if (th->ack)
seq = ntohl(th->ack_seq);
else
@@ -972,20 +974,14 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
trace_tcp_send_reset(sk, skb);
}
- tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
-
-#ifdef CONFIG_TCP_MD5SIG
-out:
- rcu_read_unlock();
-#endif
+ tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1, 0, 0);
}
static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
- struct tcp_md5sig_key *key, u8 tclass,
- __be32 label)
+ u8 tclass, __be32 label)
{
- tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, key, 0,
+ tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, 0,
tclass, label);
}
@@ -997,7 +993,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
tcp_time_stamp_raw() + tcptw->tw_ts_offset,
- tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
+ tcptw->tw_ts_recent, tw->tw_bound_dev_if,
tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel));
inet_twsk_put(tw);
@@ -1020,7 +1016,6 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
req->ts_recent, sk->sk_bound_dev_if,
- tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr),
0, 0);
}
--
2.16.1
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