From cd48bdda4fb82c2fe569d97af4217c530168c99c Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 8 Aug 2019 13:57:25 +0200 Subject: [PATCH] sock: make cookie generation global instead of per netns 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 Cc: Eric Dumazet Cc: Alexei Starovoitov Cc: Willem de Bruijn Cc: Martynas Pumputis Signed-off-by: David S. Miller --- include/net/net_namespace.h | 1 - include/uapi/linux/bpf.h | 4 ++-- net/core/sock_diag.c | 3 ++- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 4a9da951a794ef..cb668bc2692db2 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -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 diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index fa1c753dcdbc7f..a5aa7d3ac6a116 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -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*. diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c index 3312a5849a974e..c13ffbd33d8d6a 100644 --- a/net/core/sock_diag.c +++ b/net/core/sock_diag.c @@ -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); } }