linux-kernel - [PATCH v4 4/5] net/tcp: Do cleanup on tcp_md5_key

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Message-Id: <20221115211905.1685426-5-dima@arista.com>
Date:   Tue, 15 Nov 2022 21:19:04 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Dmitry Safonov <dima@...sta.com>, Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Francesco Ruggeri <fruggeri@...sta.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Jason Baron <jbaron@...mai.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Salam Noureddine <noureddine@...sta.com>,
        Steven Rostedt <rostedt@...dmis.org>, netdev@...r.kernel.org
Subject: [PATCH v4 4/5] net/tcp: Do cleanup on tcp_md5_key_copy() failure

If the kernel was short on (atomic) memory and failed to allocate it -
don't proceed to creation of request socket. Otherwise the socket would
be unsigned and userspace likely doesn't expect that the TCP is not
MD5-signed anymore.

Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 net/ipv4/tcp_ipv4.c |  9 ++-------
 net/ipv6/tcp_ipv6.c | 15 ++++++++-------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4bdb6e1ecaf3..deabf3309865 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1628,13 +1628,8 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
 	addr = (union tcp_md5_addr *)&newinet->inet_daddr;
 	key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
 	if (key) {
-		/*
-		 * We're using one, so create a matching key
-		 * on the newsk structure. If we fail to get
-		 * memory, then we end up not copying the key
-		 * across. Shucks.
-		 */
-		tcp_md5_key_copy(newsk, addr, AF_INET, 32, l3index, key);
+		if (tcp_md5_key_copy(newsk, addr, AF_INET, 32, l3index, key))
+			goto put_and_exit;
 		sk_gso_disable(newsk);
 	}
 #endif
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3e3bdc120fc8..64788cfbefc7 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1376,13 +1376,14 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 	/* Copy over the MD5 key from the original socket */
 	key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
 	if (key) {
-		/* We're using one, so create a matching key
-		 * on the newsk structure. If we fail to get
-		 * memory, then we end up not copying the key
-		 * across. Shucks.
-		 */
-		tcp_md5_key_copy(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr,
-				 AF_INET6, 128, l3index, key);
+		const union tcp_md5_addr *addr;
+
+		addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
+		if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
+			inet_csk_prepare_forced_close(newsk);
+			tcp_done(newsk);
+			goto out;
+		}
 	}
 #endif
 
-- 
2.38.1