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authorJakub Sitnicki <jakub@cloudflare.com>2020-06-25 16:13:56 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-06-30 10:45:08 -0700
commitab53cad90eb10c9991f501ba08904680a074ef3d (patch)
treea40a6f6aacc3e55888d939cf640ca754de98126f
parent695c12147a40181fe9221d321c3f2de33c9574ed (diff)
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@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200625141357.910330-4-jakub@cloudflare.com
-rw-r--r--include/net/netns/bpf.h2
-rw-r--r--kernel/bpf/net_namespace.c42
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 0dba97202357..7a34a8caf954 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c
@@ -19,21 +19,13 @@ 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;
-}
-
-/* Must be called with netns_bpf_mutex held. */
static void netns_bpf_run_array_detach(struct net *net,
enum netns_bpf_attach_type type)
{
@@ -66,7 +58,7 @@ static void bpf_netns_link_release(struct bpf_link *link)
goto out_unlock;
netns_bpf_run_array_detach(net, type);
- net->bpf.links[type] = NULL;
+ list_del(&net_link->node);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
@@ -225,7 +217,7 @@ 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;
}
@@ -279,7 +271,7 @@ 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];
@@ -310,13 +302,15 @@ 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 *run_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;
}
@@ -345,7 +339,7 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
run_array->items[0].prog = link->prog;
rcu_assign_pointer(net->bpf.run_array[type], run_array);
- net->bpf.links[type] = link;
+ list_add_tail(&net_link->node, &net->bpf.links[type]);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
@@ -404,24 +398,34 @@ out_put_net:
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,
};