From: Jakub Sitnicki <jakub@cloudflare.com>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com,
Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf-next v3 3/4] bpf, netns: Keep a list of attached bpf_link's
Date: Thu, 25 Jun 2020 16:13:56 +0200 [thread overview]
Message-ID: <20200625141357.910330-4-jakub@cloudflare.com> (raw)
In-Reply-To: <20200625141357.910330-1-jakub@cloudflare.com>
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.
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.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 0dba97202357..7a34a8caf954 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;
-}
-
/* 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 @@ 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
next prev parent reply other threads:[~2020-06-25 14:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 14:13 [PATCH bpf-next v3 0/4] bpf, netns: Prepare for multi-prog attachment Jakub Sitnicki
2020-06-25 14:13 ` [PATCH bpf-next v3 1/4] flow_dissector: Pull BPF program assignment up to bpf-netns Jakub Sitnicki
2020-06-26 1:38 ` Martin KaFai Lau
2020-06-25 14:13 ` [PATCH bpf-next v3 2/4] bpf, netns: Keep attached programs in bpf_prog_array Jakub Sitnicki
2020-06-25 20:50 ` Andrii Nakryiko
2020-06-26 9:45 ` Jakub Sitnicki
2020-06-26 22:13 ` Andrii Nakryiko
2020-06-26 22:15 ` Andrii Nakryiko
2020-06-26 5:41 ` Martin KaFai Lau
2020-06-26 10:40 ` Jakub Sitnicki
2020-06-25 14:13 ` Jakub Sitnicki [this message]
2020-06-26 5:43 ` [PATCH bpf-next v3 3/4] bpf, netns: Keep a list of attached bpf_link's Martin KaFai Lau
2020-06-25 14:13 ` [PATCH bpf-next v3 4/4] selftests/bpf: Test updating flow_dissector link with same program Jakub Sitnicki
2020-06-26 5:52 ` Martin KaFai Lau
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