sock: make cookie generation global instead of per netns (cd48bdda) · Commits · 戴 / test

Generating and retrieving socket cookies are a useful feature that is exposed to BPF for various program types through bpf_get_socket_cookie() helper. The fact that the cookie counter is per netns is quite a limitation for BPF in practice in particular for programs in host namespace that use socket cookies as part of a map lookup key since they will be causing socket cookie collisions e.g. when attached to BPF cgroup hooks or cls_bpf on tc egress in host namespace handling container traffic from veth or ipvlan devices with peer in different netns. Change the counter to be global instead. Socket cookie consumers must assume the value as opqaue in any case. Not every socket must have a cookie generated and knowledge of the counter value itself does not provide much value either way hence conversion to global is fine. Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Willem de Bruijn <willemb@google.com> Cc: Martynas Pumputis <m@lambda.lt> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/net/net_namespace.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -61,7 +61,6 @@ struct net {
		spinlock_t rules_mod_lock;

		u32 hash_mix;
		atomic64_t cookie_gen;

		struct list_head list; /* list of network namespaces */
		struct list_head exit_list; /* To linked to call pernet exit

include/uapi/linux/bpf.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -1466,8 +1466,8 @@ union bpf_attr {
		* If no cookie has been set yet, generate a new cookie. Once
		* generated, the socket cookie remains stable for the life of the
		* socket. This helper can be useful for monitoring per socket
		* networking traffic statistics as it provides a unique socket
		* identifier per namespace.
		* networking traffic statistics as it provides a global socket
		* identifier that can be assumed unique.
		* Return
		* A 8-byte long non-decreasing number on success, or 0 if the
		* socket field is missing inside skb.

net/core/sock_diag.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@ static const struct sock_diag_handler *sock_diag_handlers[AF_MAX];
		static int (inet_rcv_compat)(struct sk_buff skb, struct nlmsghdr *nlh);
		static DEFINE_MUTEX(sock_diag_table_mutex);
		static struct workqueue_struct *broadcast_wq;
		static atomic64_t cookie_gen;

		u64 sock_gen_cookie(struct sock *sk)
		{
		@@ -27,7 +28,7 @@ u64 sock_gen_cookie(struct sock *sk)

		if (res)
		return res;
		res = atomic64_inc_return(&sock_net(sk)->cookie_gen);
		res = atomic64_inc_return(&cookie_gen);
		atomic64_cmpxchg(&sk->sk_cookie, 0, res);
		}
		}

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