netdev - [PATCH bpf-next 04/14] bpf: net: Avoid do_tcp_setsockopt() taking sk lock when called from bpf

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Date:   Tue, 26 Jul 2022 23:09:21 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>, <kernel-team@...com>,
        Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH bpf-next 04/14] bpf: net: Avoid do_tcp_setsockopt() taking sk lock when called from bpf

Similar to the earlier patch that avoids sock_setsockopt() from
taking sk lock when called from bpf.  This patch changes
do_tcp_setsockopt() to use the {lock,release}_sock_sockopt().

This patch also changes do_tcp_setsockopt() to check optval.is_bpf
when passing the cap_net_admin arg to
tcp_set_congestion_control(..., cap_net_admin).  It is
the same as how bpf_setsockopt(TCP_CONGESTION) is calling
tcp_set_congestion_control() now.

Signed-off-by: Martin KaFai Lau <kafai@...com>
---
 net/ipv4/tcp.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index ba2bdc811374..7f8d81befa8e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3462,11 +3462,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 			return -EFAULT;
 		name[val] = 0;
 
-		lock_sock(sk);
-		err = tcp_set_congestion_control(sk, name, true,
-						 ns_capable(sock_net(sk)->user_ns,
-							    CAP_NET_ADMIN));
-		release_sock(sk);
+		lock_sock_sockopt(sk, optval);
+		err = tcp_set_congestion_control(sk, name, !optval.is_bpf,
+						 optval.is_bpf ?
+						 true : ns_capable(sock_net(sk)->user_ns,
+								   CAP_NET_ADMIN));
+		release_sock_sockopt(sk, optval);
 		return err;
 	}
 	case TCP_ULP: {
@@ -3482,9 +3483,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 			return -EFAULT;
 		name[val] = 0;
 
-		lock_sock(sk);
+		lock_sock_sockopt(sk, optval);
 		err = tcp_set_ulp(sk, name);
-		release_sock(sk);
+		release_sock_sockopt(sk, optval);
 		return err;
 	}
 	case TCP_FASTOPEN_KEY: {
@@ -3517,7 +3518,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 	if (copy_from_sockptr(&val, optval, sizeof(val)))
 		return -EFAULT;
 
-	lock_sock(sk);
+	lock_sock_sockopt(sk, optval);
 
 	switch (optname) {
 	case TCP_MAXSEG:
@@ -3739,7 +3740,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		break;
 	}
 
-	release_sock(sk);
+	release_sock_sockopt(sk, optval);
 	return err;
 }
 
-- 
2.30.2