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Message-Id: <20200622160300.636567-4-jakub@cloudflare.com>
Date: Mon, 22 Jun 2020 18:03:00 +0200
From: Jakub Sitnicki <jakub@...udflare.com>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org, kernel-team@...udflare.com
Subject: [PATCH bpf-next 3/3] bpf, netns: Keep a list of attached bpf_link's
To support multi-prog link-based attachments for new netns attach types, we
need to keep track of more than one bpf_link per attach type. Hence,
convert net->bpf.links into a list, that currently can be either empty or
have just one item.
Instead of reusing bpf_prog_list from bpf-cgroup, we link together
bpf_netns_link's themselves. This makes list management simpler as we don't
have to allocate, initialize, and later release list elements. We can do
this because multi-prog attachment will be available only for bpf_link, and
we don't need to build a list of programs attached directly and indirectly
via links.
No functional changes intended.
Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
---
include/net/netns/bpf.h | 2 +-
kernel/bpf/net_namespace.c | 42 +++++++++++++++++++++-----------------
2 files changed, 24 insertions(+), 20 deletions(-)
diff --git a/include/net/netns/bpf.h b/include/net/netns/bpf.h
index a5015bda9979..0ca6a1b87185 100644
--- a/include/net/netns/bpf.h
+++ b/include/net/netns/bpf.h
@@ -15,7 +15,7 @@ struct netns_bpf {
/* Array of programs to run compiled from progs or links */
struct bpf_prog_array __rcu *run_array[MAX_NETNS_BPF_ATTACH_TYPE];
struct bpf_prog *progs[MAX_NETNS_BPF_ATTACH_TYPE];
- struct bpf_link *links[MAX_NETNS_BPF_ATTACH_TYPE];
+ struct list_head links[MAX_NETNS_BPF_ATTACH_TYPE];
};
#endif /* __NETNS_BPF_H__ */
diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
index 593523a22168..3e89c7ad42cb 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c
@@ -19,20 +19,12 @@ struct bpf_netns_link {
* with netns_bpf_mutex held.
*/
struct net *net;
+ struct list_head node; /* node in list of links attached to net */
};
/* Protects updates to netns_bpf */
DEFINE_MUTEX(netns_bpf_mutex);
-/* Must be called with netns_bpf_mutex held. */
-static void __net_exit bpf_netns_link_auto_detach(struct bpf_link *link)
-{
- struct bpf_netns_link *net_link =
- container_of(link, struct bpf_netns_link, link);
-
- net_link->net = NULL;
-}
-
static void bpf_netns_link_release(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
@@ -69,7 +61,7 @@ static void bpf_netns_link_release(struct bpf_link *link)
bpf_prog_array_free(old_array);
}
- net->bpf.links[type] = NULL;
+ list_del(&net_link->node);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
@@ -233,7 +225,7 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
mutex_lock(&netns_bpf_mutex);
/* Attaching prog directly is not compatible with links */
- if (net->bpf.links[type]) {
+ if (!list_empty(&net->bpf.links[type])) {
ret = -EEXIST;
goto out_unlock;
}
@@ -296,7 +288,7 @@ static int __netns_bpf_prog_detach(struct net *net,
struct bpf_prog *attached;
/* Progs attached via links cannot be detached */
- if (net->bpf.links[type])
+ if (!list_empty(&net->bpf.links[type]))
return -EINVAL;
attached = net->bpf.progs[type];
@@ -327,13 +319,15 @@ int netns_bpf_prog_detach(const union bpf_attr *attr)
static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
enum netns_bpf_attach_type type)
{
+ struct bpf_netns_link *net_link =
+ container_of(link, struct bpf_netns_link, link);
struct bpf_prog_array *old_array, *new_array;
int err;
mutex_lock(&netns_bpf_mutex);
/* Allow attaching only one prog or link for now */
- if (net->bpf.links[type]) {
+ if (!list_empty(&net->bpf.links[type])) {
err = -E2BIG;
goto out_unlock;
}
@@ -362,7 +356,7 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
rcu_assign_pointer(net->bpf.run_array[type], new_array);
bpf_prog_array_free(old_array);
- net->bpf.links[type] = link;
+ list_add_tail(&net_link->node, &net->bpf.links[type]);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
@@ -421,24 +415,34 @@ int netns_bpf_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
return err;
}
+static int __net_init netns_bpf_pernet_init(struct net *net)
+{
+ int type;
+
+ for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++)
+ INIT_LIST_HEAD(&net->bpf.links[type]);
+
+ return 0;
+}
+
static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
{
enum netns_bpf_attach_type type;
- struct bpf_link *link;
+ struct bpf_netns_link *net_link;
mutex_lock(&netns_bpf_mutex);
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) {
netns_bpf_run_array_detach(net, type);
- link = net->bpf.links[type];
- if (link)
- bpf_netns_link_auto_detach(link);
- else if (net->bpf.progs[type])
+ list_for_each_entry(net_link, &net->bpf.links[type], node)
+ net_link->net = NULL; /* auto-detach link */
+ if (net->bpf.progs[type])
bpf_prog_put(net->bpf.progs[type]);
}
mutex_unlock(&netns_bpf_mutex);
}
static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
+ .init = netns_bpf_pernet_init,
.pre_exit = netns_bpf_pernet_pre_exit,
};
--
2.25.4
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