diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-07-18 19:28:14 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-31 07:28:46 +0200 |
| commit | adcac7370d7d9c6c8f58c590fff117d95c65fb61 (patch) | |
| tree | 29f1e5f21b991129e9b050331ff2a312f10fa810 /net/ipv4 | |
| parent | 8cf295c38ddeb44806fd71a8363cce9914a52bc4 (diff) | |
tcp: fix tcp_set_congestion_control() use from bpf hook
[ Upstream commit 8d650cdedaabb33e85e9b7c517c0c71fcecc1de9 ]
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 <edumazet@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>
Reported-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp.c | 4 | ||||
| -rw-r--r-- | net/ipv4/tcp_cong.c | 6 |
2 files changed, 6 insertions, 4 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index d51571be9eac..2497735f4b03 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2500,7 +2500,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level, name[val] = 0; lock_sock(sk); - err = tcp_set_congestion_control(sk, name, true, true); + err = tcp_set_congestion_control(sk, name, true, true, + ns_capable(sock_net(sk)->user_ns, + CAP_NET_ADMIN)); release_sock(sk); return err; } diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 2f26124fd160..494e3c3a21a1 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -338,7 +338,8 @@ out: * tcp_reinit_congestion_control (if the current congestion control was * already initialized. */ -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) { struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_congestion_ops *ca; @@ -372,8 +373,7 @@ int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, boo } else { err = -EBUSY; } - } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || - ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) { + } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || cap_net_admin)) { err = -EPERM; } else if (!try_module_get(ca->owner)) { err = -EBUSY; |