We will support arbitrary SYN Cookie with BPF, and then kfunc at
TC will preallocate reqsk and initialise some fields that should
not be overwritten later by cookie_v[46]_check().
To simplify the flow in cookie_v[46]_check(), we move such fields'
initialisation to cookie_tcp_reqsk_alloc() and factorise non-BPF
SYN Cookie handling into cookie_tcp_check(), where we validate the
cookie and allocate reqsk, as done by kfunc later.
Note that we set ireq->ecn_ok in two steps, the latter of which will
be shared by the BPF case. As cookie_ecn_ok() is one-liner, now
it's inlined.
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
include/net/tcp.h | 13 ++++--
net/ipv4/syncookies.c | 106 +++++++++++++++++++++++-------------------
net/ipv6/syncookies.c | 61 ++++++++++++------------
3 files changed, 99 insertions(+), 81 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d4d0e9763175..973555cb1d3f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -494,7 +494,10 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
- struct sock *sk, struct sk_buff *skb);
+ struct sock *sk, struct sk_buff *skb,
+ struct tcp_options_received *tcp_opt,
+ int mss, u32 tsoff);
+
#ifdef CONFIG_SYN_COOKIES
/* Syncookies use a monotonic timer which increments every 60 seconds.
@@ -580,8 +583,12 @@ __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
u64 cookie_init_timestamp(struct request_sock *req, u64 now);
bool cookie_timestamp_decode(const struct net *net,
struct tcp_options_received *opt);
-bool cookie_ecn_ok(const struct tcp_options_received *opt,
- const struct net *net, const struct dst_entry *dst);
+
+static inline bool cookie_ecn_ok(const struct net *net, const struct dst_entry *dst)
+{
+ return READ_ONCE(net->ipv4.sysctl_tcp_ecn) ||
+ dst_feature(dst, RTAX_FEATURE_ECN);
+}
/* From net/ipv6/syncookies.c */
int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th);
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 9bca1c026525..beea4d05fafc 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -270,21 +270,6 @@ bool cookie_timestamp_decode(const struct net *net,
}
EXPORT_SYMBOL(cookie_timestamp_decode);
-bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt,
- const struct net *net, const struct dst_entry *dst)
-{
- bool ecn_ok = tcp_opt->rcv_tsecr & TS_OPT_ECN;
-
- if (!ecn_ok)
- return false;
-
- if (READ_ONCE(net->ipv4.sysctl_tcp_ecn))
- return true;
-
- return dst_feature(dst, RTAX_FEATURE_ECN);
-}
-EXPORT_SYMBOL(cookie_ecn_ok);
-
static int cookie_tcp_reqsk_init(struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
@@ -321,8 +306,12 @@ static int cookie_tcp_reqsk_init(struct sock *sk, struct sk_buff *skb,
}
struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
- struct sock *sk, struct sk_buff *skb)
+ struct sock *sk, struct sk_buff *skb,
+ struct tcp_options_received *tcp_opt,
+ int mss, u32 tsoff)
{
+ struct inet_request_sock *ireq;
+ struct tcp_request_sock *treq;
struct request_sock *req;
if (sk_is_mptcp(sk))
@@ -338,40 +327,36 @@ struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
return NULL;
}
+ ireq = inet_rsk(req);
+ treq = tcp_rsk(req);
+
+ req->mss = mss;
+ req->ts_recent = tcp_opt->saw_tstamp ? tcp_opt->rcv_tsval : 0;
+
+ ireq->snd_wscale = tcp_opt->snd_wscale;
+ ireq->tstamp_ok = tcp_opt->saw_tstamp;
+ ireq->sack_ok = tcp_opt->sack_ok;
+ ireq->wscale_ok = tcp_opt->wscale_ok;
+ ireq->ecn_ok = tcp_opt->rcv_tsecr & TS_OPT_ECN;
+
+ treq->ts_off = tsoff;
+
return req;
}
EXPORT_SYMBOL_GPL(cookie_tcp_reqsk_alloc);
-/* On input, sk is a listener.
- * Output is listener if incoming packet would not create a child
- * NULL if memory could not be allocated.
- */
-struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
+static struct request_sock *cookie_tcp_check(struct net *net, struct sock *sk,
+ struct sk_buff *skb)
{
- struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
- const struct tcphdr *th = tcp_hdr(skb);
struct tcp_options_received tcp_opt;
- struct tcp_sock *tp = tcp_sk(sk);
- struct inet_request_sock *ireq;
- struct net *net = sock_net(sk);
- struct tcp_request_sock *treq;
- struct request_sock *req;
- struct sock *ret = sk;
- int full_space, mss;
- struct flowi4 fl4;
- struct rtable *rt;
- __u8 rcv_wscale;
u32 tsoff = 0;
-
- if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
- !th->ack || th->rst)
- goto out;
+ int mss;
if (tcp_synq_no_recent_overflow(sk))
goto out;
- mss = __cookie_v4_check(ip_hdr(skb), th);
- if (mss == 0) {
+ mss = __cookie_v4_check(ip_hdr(skb), tcp_hdr(skb));
+ if (!mss) {
__NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESFAILED);
goto out;
}
@@ -392,21 +377,44 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
if (!cookie_timestamp_decode(net, &tcp_opt))
goto out;
- req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops, sk, skb);
+ return cookie_tcp_reqsk_alloc(&tcp_request_sock_ops, sk, skb,
+ &tcp_opt, mss, tsoff);
+out:
+ return ERR_PTR(-EINVAL);
+}
+
+/* On input, sk is a listener.
+ * Output is listener if incoming packet would not create a child
+ * NULL if memory could not be allocated.
+ */
+struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
+{
+ struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
+ const struct tcphdr *th = tcp_hdr(skb);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct inet_request_sock *ireq;
+ struct net *net = sock_net(sk);
+ struct request_sock *req;
+ struct sock *ret = sk;
+ struct flowi4 fl4;
+ struct rtable *rt;
+ __u8 rcv_wscale;
+ int full_space;
+
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
+ !th->ack || th->rst)
+ goto out;
+
+ req = cookie_tcp_check(net, sk, skb);
+ if (IS_ERR(req))
+ goto out;
if (!req)
goto out_drop;
ireq = inet_rsk(req);
- treq = tcp_rsk(req);
- treq->ts_off = tsoff;
- req->mss = mss;
+
sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
- ireq->snd_wscale = tcp_opt.snd_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)
@@ -448,7 +456,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
dst_metric(&rt->dst, RTAX_INITRWND));
ireq->rcv_wscale = rcv_wscale;
- ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, net, &rt->dst);
+ ireq->ecn_ok &= cookie_ecn_ok(net, &rt->dst);
ret = tcp_get_cookie_sock(sk, skb, req, &rt->dst);
/* ip_queue_xmit() depends on our flow being setup
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index e0a9220d1536..c8d2ca27220c 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -127,31 +127,18 @@ int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th)
}
EXPORT_SYMBOL_GPL(__cookie_v6_check);
-struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
+static struct request_sock *cookie_tcp_check(struct net *net, struct sock *sk,
+ struct sk_buff *skb)
{
- const struct tcphdr *th = tcp_hdr(skb);
- struct ipv6_pinfo *np = inet6_sk(sk);
struct tcp_options_received tcp_opt;
- struct tcp_sock *tp = tcp_sk(sk);
- struct inet_request_sock *ireq;
- struct net *net = sock_net(sk);
- struct tcp_request_sock *treq;
- struct request_sock *req;
- struct dst_entry *dst;
- struct sock *ret = sk;
- int full_space, mss;
- __u8 rcv_wscale;
u32 tsoff = 0;
-
- if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
- !th->ack || th->rst)
- goto out;
+ int mss;
if (tcp_synq_no_recent_overflow(sk))
goto out;
- mss = __cookie_v6_check(ipv6_hdr(skb), th);
- if (mss == 0) {
+ mss = __cookie_v6_check(ipv6_hdr(skb), tcp_hdr(skb));
+ if (!mss) {
__NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESFAILED);
goto out;
}
@@ -172,14 +159,37 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
if (!cookie_timestamp_decode(net, &tcp_opt))
goto out;
- req = cookie_tcp_reqsk_alloc(&tcp6_request_sock_ops, sk, skb);
+ return cookie_tcp_reqsk_alloc(&tcp6_request_sock_ops, sk, skb,
+ &tcp_opt, mss, tsoff);
+out:
+ return ERR_PTR(-EINVAL);
+}
+
+struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
+{
+ const struct tcphdr *th = tcp_hdr(skb);
+ struct ipv6_pinfo *np = inet6_sk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct inet_request_sock *ireq;
+ struct net *net = sock_net(sk);
+ struct request_sock *req;
+ struct dst_entry *dst;
+ struct sock *ret = sk;
+ __u8 rcv_wscale;
+ int full_space;
+
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
+ !th->ack || th->rst)
+ goto out;
+
+ req = cookie_tcp_check(net, sk, skb);
+ if (IS_ERR(req))
+ goto out;
if (!req)
goto out_drop;
ireq = inet_rsk(req);
- treq = tcp_rsk(req);
- req->mss = mss;
ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
@@ -198,13 +208,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
ireq->ir_iif = tcp_v6_iif(skb);
- ireq->snd_wscale = tcp_opt.snd_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;
- treq->ts_off = tsoff;
-
tcp_ao_syncookie(sk, skb, req, AF_INET6);
/*
@@ -245,7 +248,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
dst_metric(dst, RTAX_INITRWND));
ireq->rcv_wscale = rcv_wscale;
- ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, net, dst);
+ ireq->ecn_ok &= cookie_ecn_ok(net, dst);
ret = tcp_get_cookie_sock(sk, skb, req, dst);
out:
--
2.30.2
