lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20200821151544.1211989-3-nicolas.rybowski@tessares.net>
Date:   Fri, 21 Aug 2020 17:15:40 +0200
From:   Nicolas Rybowski <nicolas.rybowski@...sares.net>
To:     Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Matthieu Baerts <matthieu.baerts@...sares.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>
Cc:     Nicolas Rybowski <nicolas.rybowski@...sares.net>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        mptcp@...ts.01.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH bpf-next 2/3] mptcp: attach subflow socket to parent cgroup

It has been observed that the kernel sockets created for the subflows
(except the first one) are not in the same cgroup as their parents.
That's because the additional subflows are created by kernel workers.

This is a problem with eBPF programs attached to the parent's
cgroup won't be executed for the children. But also with any other features
of CGroup linked to a sk.

This patch fixes this behaviour.

As the subflow sockets are created by the kernel, we can't use
'mem_cgroup_sk_alloc' because of the current context being the one of the
kworker. This is why we have to do low level memcg manipulation, if
required.

Suggested-by: Matthieu Baerts <matthieu.baerts@...sares.net>
Suggested-by: Paolo Abeni <pabeni@...hat.com>
Acked-by: Matthieu Baerts <matthieu.baerts@...sares.net>
Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
Signed-off-by: Nicolas Rybowski <nicolas.rybowski@...sares.net>
---
 net/mptcp/subflow.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index e8cac2655c82..535a3f9f8cfc 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1130,6 +1130,30 @@ int __mptcp_subflow_connect(struct sock *sk, int ifindex,
 	return err;
 }
 
+static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
+{
+#ifdef CONFIG_SOCK_CGROUP_DATA
+	struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
+				*child_skcd = &child->sk_cgrp_data;
+
+	/* only the additional subflows created by kworkers have to be modified */
+	if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
+	    cgroup_id(sock_cgroup_ptr(child_skcd))) {
+#ifdef CONFIG_MEMCG
+		struct mem_cgroup *memcg = parent->sk_memcg;
+
+		mem_cgroup_sk_free(child);
+		if (memcg && css_tryget(&memcg->css))
+			child->sk_memcg = memcg;
+#endif /* CONFIG_MEMCG */
+
+		cgroup_sk_free(child_skcd);
+		*child_skcd = *parent_skcd;
+		cgroup_sk_clone(child_skcd);
+	}
+#endif /* CONFIG_SOCK_CGROUP_DATA */
+}
+
 int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
 {
 	struct mptcp_subflow_context *subflow;
@@ -1150,6 +1174,9 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
 
 	lock_sock(sf->sk);
 
+	/* the newly created socket has to be in the same cgroup as its parent */
+	mptcp_attach_cgroup(sk, sf->sk);
+
 	/* kernel sockets do not by default acquire net ref, but TCP timer
 	 * needs it.
 	 */
-- 
2.28.0

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ