From 8d650cdedaabb33e85e9b7c517c0c71fcecc1de9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Jul 2019 19:28:14 -0700 Subject: tcp: fix tcp_set_congestion_control() use from bpf hook Neal reported incorrect use of ns_capable() from bpf hook. bpf_setsockopt(...TCP_CONGESTION...) -> tcp_set_congestion_control() -> ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN) -> ns_capable_common() -> current_cred() -> rcu_dereference_protected(current->cred, 1) Accessing 'current' in bpf context makes no sense, since packets are processed from softirq context. As Neal stated : The capability check in tcp_set_congestion_control() was written assuming a system call context, and then was reused from a BPF call site. The fix is to add a new parameter to tcp_set_congestion_control(), so that the ns_capable() call is only performed under the right context. Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control") Signed-off-by: Eric Dumazet Cc: Lawrence Brakmo Reported-by: Neal Cardwell Acked-by: Neal Cardwell Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller --- include/net/tcp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/tcp.h b/include/net/tcp.h index cca3c59b98bf..f42d300f0cfa 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1064,7 +1064,8 @@ void tcp_get_default_congestion_control(struct net *net, char *name); void tcp_get_available_congestion_control(char *buf, size_t len); void tcp_get_allowed_congestion_control(char *buf, size_t len); int tcp_set_allowed_congestion_control(char *allowed); -int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, + bool reinit, bool cap_net_admin); u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); -- cgit v1.2.3-59-g8ed1b