flow_dissector: Move out netns_bpf prog callbacks
Move functions to manage BPF programs attached to netns that are not
specific to flow dissector to a dedicated module named
bpf/net_namespace.c.
The set of functions will grow with the addition of bpf_link support for
netns attached programs. This patch prepares ground by creating a place
for it.
This is a code move with no functional changes intended.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200531082846.2117903-4-jakub@cloudflare.com
diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
new file mode 100644
index 0000000..b37d814
--- /dev/null
+++ b/kernel/bpf/net_namespace.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <net/net_namespace.h>
+
+/*
+ * Functions to manage BPF programs attached to netns
+ */
+
+/* Protects updates to netns_bpf */
+DEFINE_MUTEX(netns_bpf_mutex);
+
+int netns_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
+ u32 prog_id, prog_cnt = 0, flags = 0;
+ enum netns_bpf_attach_type type;
+ struct bpf_prog *attached;
+ struct net *net;
+
+ if (attr->query.query_flags)
+ return -EINVAL;
+
+ type = to_netns_bpf_attach_type(attr->query.attach_type);
+ if (type < 0)
+ return -EINVAL;
+
+ net = get_net_ns_by_fd(attr->query.target_fd);
+ if (IS_ERR(net))
+ return PTR_ERR(net);
+
+ rcu_read_lock();
+ attached = rcu_dereference(net->bpf.progs[type]);
+ if (attached) {
+ prog_cnt = 1;
+ prog_id = attached->aux->id;
+ }
+ rcu_read_unlock();
+
+ put_net(net);
+
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
+ return -EFAULT;
+ if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
+ return -EFAULT;
+
+ if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
+ return 0;
+
+ if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
+ return -EFAULT;
+
+ return 0;
+}
+
+int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+ enum netns_bpf_attach_type type;
+ struct net *net;
+ int ret;
+
+ type = to_netns_bpf_attach_type(attr->attach_type);
+ if (type < 0)
+ return -EINVAL;
+
+ net = current->nsproxy->net_ns;
+ mutex_lock(&netns_bpf_mutex);
+ switch (type) {
+ case NETNS_BPF_FLOW_DISSECTOR:
+ ret = flow_dissector_bpf_prog_attach(net, prog);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+ mutex_unlock(&netns_bpf_mutex);
+
+ return ret;
+}
+
+/* Must be called with netns_bpf_mutex held. */
+static int __netns_bpf_prog_detach(struct net *net,
+ enum netns_bpf_attach_type type)
+{
+ struct bpf_prog *attached;
+
+ attached = rcu_dereference_protected(net->bpf.progs[type],
+ lockdep_is_held(&netns_bpf_mutex));
+ if (!attached)
+ return -ENOENT;
+ RCU_INIT_POINTER(net->bpf.progs[type], NULL);
+ bpf_prog_put(attached);
+ return 0;
+}
+
+int netns_bpf_prog_detach(const union bpf_attr *attr)
+{
+ enum netns_bpf_attach_type type;
+ int ret;
+
+ type = to_netns_bpf_attach_type(attr->attach_type);
+ if (type < 0)
+ return -EINVAL;
+
+ mutex_lock(&netns_bpf_mutex);
+ ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type);
+ mutex_unlock(&netns_bpf_mutex);
+
+ return ret;
+}
+
+static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
+{
+ enum netns_bpf_attach_type type;
+
+ mutex_lock(&netns_bpf_mutex);
+ for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++)
+ __netns_bpf_prog_detach(net, type);
+ mutex_unlock(&netns_bpf_mutex);
+}
+
+static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
+ .pre_exit = netns_bpf_pernet_pre_exit,
+};
+
+static int __init netns_bpf_init(void)
+{
+ return register_pernet_subsys(&netns_bpf_pernet_ops);
+}
+
+subsys_initcall(netns_bpf_init);