af_unix: Implement ->psock_update_sk_prot()
Now we can implement unix_bpf_update_proto() to update
sk_prot, especially prot->close().
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-7-xiyou.wangcong@gmail.com
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
new file mode 100644
index 0000000..b1582a6
--- /dev/null
+++ b/net/unix/unix_bpf.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */
+
+#include <linux/skmsg.h>
+#include <linux/bpf.h>
+#include <net/sock.h>
+#include <net/af_unix.h>
+
+static struct proto *unix_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(unix_prot_lock);
+static struct proto unix_bpf_prot;
+
+static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+{
+ *prot = *base;
+ prot->close = sock_map_close;
+}
+
+static void unix_bpf_check_needs_rebuild(struct proto *ops)
+{
+ if (unlikely(ops != smp_load_acquire(&unix_prot_saved))) {
+ spin_lock_bh(&unix_prot_lock);
+ if (likely(ops != unix_prot_saved)) {
+ unix_bpf_rebuild_protos(&unix_bpf_prot, ops);
+ smp_store_release(&unix_prot_saved, ops);
+ }
+ spin_unlock_bh(&unix_prot_lock);
+ }
+}
+
+int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+ if (restore) {
+ sk->sk_write_space = psock->saved_write_space;
+ WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+ return 0;
+ }
+
+ unix_bpf_check_needs_rebuild(psock->sk_proto);
+ WRITE_ONCE(sk->sk_prot, &unix_bpf_prot);
+ return 0;
+}
+
+void __init unix_bpf_build_proto(void)
+{
+ unix_bpf_rebuild_protos(&unix_bpf_prot, &unix_proto);
+}
