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From: Lorenz Bauer <lmb@cloudflare.com>
To: Eric Dumazet <edumazet@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jakub Sitnicki <jakub@cloudflare.com>,
	Lorenz Bauer <lmb@cloudflare.com>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Alexei Starovoitov <ast@kernel.org>
Cc: kernel-team@cloudflare.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next v4 03/12] bpf: tcp: move assertions into tcp_bpf_get_proto
Date: Mon,  9 Mar 2020 11:12:34 +0000	[thread overview]
Message-ID: <20200309111243.6982-4-lmb@cloudflare.com> (raw)
In-Reply-To: <20200309111243.6982-1-lmb@cloudflare.com>

We need to ensure that sk->sk_prot uses certain callbacks, so that
code that directly calls e.g. tcp_sendmsg in certain corner cases
works. To avoid spurious asserts, we must to do this only if
sk_psock_update_proto has not yet been called. The same invariants
apply for tcp_bpf_check_v6_needs_rebuild, so move the call as well.

Doing so allows us to merge tcp_bpf_init and tcp_bpf_reinit.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
---
 include/net/tcp.h   |  1 -
 net/core/sock_map.c | 25 +++++++++----------------
 net/ipv4/tcp_bpf.c  | 42 ++++++++++++++++++++++--------------------
 3 files changed, 31 insertions(+), 37 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 07f947cc80e6..ccf39d80b695 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2196,7 +2196,6 @@ struct sk_msg;
 struct sk_psock;
 
 int tcp_bpf_init(struct sock *sk);
-void tcp_bpf_reinit(struct sock *sk);
 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
 			  int flags);
 int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index cb8f740f7949..fafcbd22ecba 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -145,8 +145,8 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
 			 struct sock *sk)
 {
 	struct bpf_prog *msg_parser, *skb_parser, *skb_verdict;
-	bool skb_progs, sk_psock_is_new = false;
 	struct sk_psock *psock;
+	bool skb_progs;
 	int ret;
 
 	skb_verdict = READ_ONCE(progs->skb_verdict);
@@ -191,18 +191,14 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
 			ret = -ENOMEM;
 			goto out_progs;
 		}
-		sk_psock_is_new = true;
 	}
 
 	if (msg_parser)
 		psock_set_prog(&psock->progs.msg_parser, msg_parser);
-	if (sk_psock_is_new) {
-		ret = tcp_bpf_init(sk);
-		if (ret < 0)
-			goto out_drop;
-	} else {
-		tcp_bpf_reinit(sk);
-	}
+
+	ret = tcp_bpf_init(sk);
+	if (ret < 0)
+		goto out_drop;
 
 	write_lock_bh(&sk->sk_callback_lock);
 	if (skb_progs && !psock->parser.enabled) {
@@ -239,15 +235,12 @@ static int sock_map_link_no_progs(struct bpf_map *map, struct sock *sk)
 	if (IS_ERR(psock))
 		return PTR_ERR(psock);
 
-	if (psock) {
-		tcp_bpf_reinit(sk);
-		return 0;
+	if (!psock) {
+		psock = sk_psock_init(sk, map->numa_node);
+		if (!psock)
+			return -ENOMEM;
 	}
 
-	psock = sk_psock_init(sk, map->numa_node);
-	if (!psock)
-		return -ENOMEM;
-
 	ret = tcp_bpf_init(sk);
 	if (ret < 0)
 		sk_psock_put(sk, psock);
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 3327afa05c3d..ed8a8f3c9afe 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -629,14 +629,6 @@ static int __init tcp_bpf_v4_build_proto(void)
 }
 core_initcall(tcp_bpf_v4_build_proto);
 
-static void tcp_bpf_update_sk_prot(struct sock *sk, struct sk_psock *psock)
-{
-	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
-	int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
-
-	sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config]);
-}
-
 static int tcp_bpf_assert_proto_ops(struct proto *ops)
 {
 	/* In order to avoid retpoline, we make assumptions when we call
@@ -648,34 +640,44 @@ static int tcp_bpf_assert_proto_ops(struct proto *ops)
 	       ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
 }
 
-void tcp_bpf_reinit(struct sock *sk)
+static struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
 {
-	struct sk_psock *psock;
+	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
+	int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
 
-	sock_owned_by_me(sk);
+	if (!psock->sk_proto) {
+		struct proto *ops = READ_ONCE(sk->sk_prot);
 
-	rcu_read_lock();
-	psock = sk_psock(sk);
-	tcp_bpf_update_sk_prot(sk, psock);
-	rcu_read_unlock();
+		if (tcp_bpf_assert_proto_ops(ops))
+			return ERR_PTR(-EINVAL);
+
+		tcp_bpf_check_v6_needs_rebuild(sk, ops);
+	}
+
+	return &tcp_bpf_prots[family][config];
 }
 
 int tcp_bpf_init(struct sock *sk)
 {
-	struct proto *ops = READ_ONCE(sk->sk_prot);
 	struct sk_psock *psock;
+	struct proto *prot;
 
 	sock_owned_by_me(sk);
 
 	rcu_read_lock();
 	psock = sk_psock(sk);
-	if (unlikely(!psock || psock->sk_proto ||
-		     tcp_bpf_assert_proto_ops(ops))) {
+	if (unlikely(!psock)) {
 		rcu_read_unlock();
 		return -EINVAL;
 	}
-	tcp_bpf_check_v6_needs_rebuild(sk, ops);
-	tcp_bpf_update_sk_prot(sk, psock);
+
+	prot = tcp_bpf_get_proto(sk, psock);
+	if (IS_ERR(prot)) {
+		rcu_read_unlock();
+		return PTR_ERR(prot);
+	}
+
+	sk_psock_update_proto(sk, psock, prot);
 	rcu_read_unlock();
 	return 0;
 }
-- 
2.20.1


  parent reply	other threads:[~2020-03-09 11:14 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200309111243.6982-1-lmb@cloudflare.com>
2020-03-09 11:12 ` [PATCH bpf-next v4 01/12] bpf: sockmap: only check ULP for TCP sockets Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 02/12] skmsg: update saved hooks only once Lorenz Bauer
2020-03-09 11:12 ` Lorenz Bauer [this message]
2020-03-09 11:12 ` [PATCH bpf-next v4 04/12] bpf: tcp: guard declarations with CONFIG_NET_SOCK_MSG Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 05/12] bpf: sockmap: move generic sockmap hooks from BPF TCP Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 06/12] bpf: sockmap: simplify sock_map_init_proto Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 07/12] bpf: add sockmap hooks for UDP sockets Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 08/12] bpf: sockmap: add UDP support Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 09/12] selftests: bpf: don't listen() on UDP sockets Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 10/12] selftests: bpf: add tests for UDP sockets in sockmap Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 11/12] selftests: bpf: enable UDP sockmap reuseport tests Lorenz Bauer
2020-03-09 11:12 ` [PATCH bpf-next v4 12/12] bpf, doc: update maintainers for L7 BPF Lorenz Bauer

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