linux-kernel - [PATCH 5.15 075/135] sock: redo the psock vs ULP protection check

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Message-Id: <20220627111940.337879163@linuxfoundation.org>
Date:   Mon, 27 Jun 2022 13:21:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 075/135] sock: redo the psock vs ULP protection check

From: Jakub Kicinski <kuba@...nel.org>

[ Upstream commit e34a07c0ae3906f97eb18df50902e2a01c1015b6 ]

Commit 8a59f9d1e3d4 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
has moved the inet_csk_has_ulp(sk) check from sk_psock_init() to
the new tcp_bpf_update_proto() function. I'm guessing that this
was done to allow creating psocks for non-inet sockets.

Unfortunately the destruction path for psock includes the ULP
unwind, so we need to fail the sk_psock_init() itself.
Otherwise if ULP is already present we'll notice that later,
and call tcp_update_ulp() with the sk_proto of the ULP
itself, which will most likely result in the ULP looping
its callbacks.

Fixes: 8a59f9d1e3d4 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Reviewed-by: John Fastabend <john.fastabend@...il.com>
Reviewed-by: Jakub Sitnicki <jakub@...udflare.com>
Tested-by: Jakub Sitnicki <jakub@...udflare.com>
Link: https://lore.kernel.org/r/20220620191353.1184629-2-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/net/inet_sock.h | 5 +++++
 net/core/skmsg.c        | 5 +++++
 net/ipv4/tcp_bpf.c      | 3 ---
 net/tls/tls_main.c      | 2 ++
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 9e1111f5915b..d81b7f85819e 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -252,6 +252,11 @@ struct inet_sock {
 #define IP_CMSG_CHECKSUM	BIT(7)
 #define IP_CMSG_RECVFRAGSIZE	BIT(8)
 
+static inline bool sk_is_inet(struct sock *sk)
+{
+	return sk->sk_family == AF_INET || sk->sk_family == AF_INET6;
+}
+
 /**
  * sk_to_full_sk - Access to a full socket
  * @sk: pointer to a socket
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index cc381165ea08..ede0af308f40 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -695,6 +695,11 @@ struct sk_psock *sk_psock_init(struct sock *sk, int node)
 
 	write_lock_bh(&sk->sk_callback_lock);
 
+	if (sk_is_inet(sk) && inet_csk_has_ulp(sk)) {
+		psock = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
 	if (sk->sk_user_data) {
 		psock = ERR_PTR(-EBUSY);
 		goto out;
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 1cdcb4df0eb7..2c597a4e429a 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -612,9 +612,6 @@ int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 		return 0;
 	}
 
-	if (inet_csk_has_ulp(sk))
-		return -EINVAL;
-
 	if (sk->sk_family == AF_INET6) {
 		if (tcp_bpf_assert_proto_ops(psock->sk_proto))
 			return -EINVAL;
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 9aac9c60d786..62b1c5e32bbd 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -790,6 +790,8 @@ static void tls_update(struct sock *sk, struct proto *p,
 {
 	struct tls_context *ctx;
 
+	WARN_ON_ONCE(sk->sk_prot == p);
+
 	ctx = tls_get_ctx(sk);
 	if (likely(ctx)) {
 		ctx->sk_write_space = write_space;
-- 
2.35.1