For non-initial network NS, the net cookie is generated when
bpf_get_netns_cookie_sock is called for the first time, but it is more
reasonable to complete the cookie generation work when creating a new
network NS, just like init_net.
net_gen_cookie() be moved into setup_net() that it can serve the initial
and non-initial network namespace.
Signed-off-by: Jianlin Lv <[email protected]>
---
net/core/net_namespace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index dcd61aca343e..5937bd0df56d 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -336,6 +336,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
idr_init(&net->netns_ids);
spin_lock_init(&net->nsid_lock);
mutex_init(&net->ipv4.ra_mutex);
+ net_gen_cookie(net);
list_for_each_entry(ops, &pernet_list, list) {
error = ops_init(ops, net);
@@ -1101,7 +1102,6 @@ static int __init net_ns_init(void)
panic("Could not allocate generic netns");
rcu_assign_pointer(init_net.gen, ng);
- net_gen_cookie(&init_net);
down_write(&pernet_ops_rwsem);
if (setup_net(&init_net, &init_user_ns))
--
2.17.1
On 7/20/20 4:09 PM, Jianlin Lv wrote:
> For non-initial network NS, the net cookie is generated when
> bpf_get_netns_cookie_sock is called for the first time, but it is more
> reasonable to complete the cookie generation work when creating a new
> network NS, just like init_net.
> net_gen_cookie() be moved into setup_net() that it can serve the initial
> and non-initial network namespace.
>
> Signed-off-by: Jianlin Lv <[email protected]>
What use-case are you trying to solve? Why should it be different than, say,
socket cookie generation? I'm currently not seeing much of a point in moving
this. When it's not used in the system, it would actually create more work.
> ---
> net/core/net_namespace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index dcd61aca343e..5937bd0df56d 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -336,6 +336,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
> idr_init(&net->netns_ids);
> spin_lock_init(&net->nsid_lock);
> mutex_init(&net->ipv4.ra_mutex);
> + net_gen_cookie(net);
>
> list_for_each_entry(ops, &pernet_list, list) {
> error = ops_init(ops, net);
> @@ -1101,7 +1102,6 @@ static int __init net_ns_init(void)
> panic("Could not allocate generic netns");
>
> rcu_assign_pointer(init_net.gen, ng);
> - net_gen_cookie(&init_net);
>
> down_write(&pernet_ops_rwsem);
> if (setup_net(&init_net, &init_user_ns))
>
> -----Original Message-----
> From: [email protected] <[email protected]> On Behalf
> Of Daniel Borkmann
> Sent: Wednesday, July 22, 2020 4:18 AM
> To: Jianlin Lv <[email protected]>; [email protected]
> Cc: [email protected]; [email protected]; [email protected]; [email protected];
> Song Zhu <[email protected]>; [email protected];
> [email protected]
> Subject: Re: [PATCH bpf-next] bpf: Generate cookie for new non-initial net NS
>
> On 7/20/20 4:09 PM, Jianlin Lv wrote:
> > For non-initial network NS, the net cookie is generated when
> > bpf_get_netns_cookie_sock is called for the first time, but it is more
> > reasonable to complete the cookie generation work when creating a new
> > network NS, just like init_net.
> > net_gen_cookie() be moved into setup_net() that it can serve the
> > initial and non-initial network namespace.
> >
> > Signed-off-by: Jianlin Lv <[email protected]>
>
> What use-case are you trying to solve? Why should it be different than, say,
> socket cookie generation? I'm currently not seeing much of a point in moving
> this. When it's not used in the system, it would actually create more work.
This patch does not come from use-case, but based on the following points were considered:
1. setup_net() runs the initializers for the network namespace object, net_cookie is a member of struct net, and its initialization is more reasonable in setup_net();
2. For initial network namespaces, this patch does not introduce additional burden;
3. For systems that have not created non-initial network namespaces, this will not introduce additional work;
4. For newly created non-initial network namespaces, the added effort of net_gen_cookie() is weak for the entire network namespaces creation process, and net_cookie is only written once during the entire life cycle of network namespaces.
>
> > ---
> > net/core/net_namespace.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index
> > dcd61aca343e..5937bd0df56d 100644
> > --- a/net/core/net_namespace.c
> > +++ b/net/core/net_namespace.c
> > @@ -336,6 +336,7 @@ static __net_init int setup_net(struct net *net,
> struct user_namespace *user_ns)
> > idr_init(&net->netns_ids);
> > spin_lock_init(&net->nsid_lock);
> > mutex_init(&net->ipv4.ra_mutex);
> > +net_gen_cookie(net);
> >
> > list_for_each_entry(ops, &pernet_list, list) {
> > error = ops_init(ops, net);
> > @@ -1101,7 +1102,6 @@ static int __init net_ns_init(void)
> > panic("Could not allocate generic netns");
> >
> > rcu_assign_pointer(init_net.gen, ng);
> > -net_gen_cookie(&init_net);
> >
> > down_write(&pernet_ops_rwsem);
> > if (setup_net(&init_net, &init_user_ns))
> >
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