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Date: Mon, 19 Apr 2021 10:55:56 -0700
From: Cong Wang <xiyou.wangcong@...il.com>
To: netdev@...r.kernel.org
Cc: bpf@...r.kernel.org, jiang.wang@...edance.com,
duanxiongchun@...edance.com, wangdongdong.6@...edance.com,
Cong Wang <cong.wang@...edance.com>,
John Fastabend <john.fastabend@...il.com>,
Daniel Borkmann <daniel@...earbox.net>,
Jakub Sitnicki <jakub@...udflare.com>,
Lorenz Bauer <lmb@...udflare.com>
Subject: [Patch bpf-next v2 2/9] af_unix: implement ->psock_update_sk_prot()
From: Cong Wang <cong.wang@...edance.com>
unix_proto is special, it is very different from INET proto,
which even does not have a ->close(). We have to add a dummy
one to satisfy sockmap.
And now we can implement unix_bpf_update_proto() to update
sk_prot.
Cc: John Fastabend <john.fastabend@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Jakub Sitnicki <jakub@...udflare.com>
Cc: Lorenz Bauer <lmb@...udflare.com>
Signed-off-by: Cong Wang <cong.wang@...edance.com>
---
MAINTAINERS | 1 +
include/net/af_unix.h | 10 ++++++++++
net/core/sock_map.c | 1 +
net/unix/Makefile | 1 +
net/unix/af_unix.c | 12 ++++++++++-
net/unix/unix_bpf.c | 46 +++++++++++++++++++++++++++++++++++++++++++
6 files changed, 70 insertions(+), 1 deletion(-)
create mode 100644 net/unix/unix_bpf.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 217c7470bfa9..02532e11da5b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10000,6 +10000,7 @@ F: net/core/skmsg.c
F: net/core/sock_map.c
F: net/ipv4/tcp_bpf.c
F: net/ipv4/udp_bpf.c
+F: net/unix/unix_bpf.c
LANTIQ / INTEL Ethernet drivers
M: Hauke Mehrtens <hauke@...ke-m.de>
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index f42fdddecd41..cca645846af1 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -89,4 +89,14 @@ void unix_sysctl_unregister(struct net *net);
static inline int unix_sysctl_register(struct net *net) { return 0; }
static inline void unix_sysctl_unregister(struct net *net) {}
#endif
+
+#ifdef CONFIG_BPF_SYSCALL
+extern struct proto unix_proto;
+
+int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
+void __init unix_bpf_build_proto(void);
+#else
+static inline void __init unix_bpf_build_proto(void)
+{}
+#endif
#endif
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 6f1b82b8ad49..1107c9dcc969 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1536,6 +1536,7 @@ void sock_map_close(struct sock *sk, long timeout)
release_sock(sk);
saved_close(sk, timeout);
}
+EXPORT_SYMBOL_GPL(sock_map_close);
static int sock_map_iter_attach_target(struct bpf_prog *prog,
union bpf_iter_link_info *linfo,
diff --git a/net/unix/Makefile b/net/unix/Makefile
index 54e58cc4f945..20491825b4d0 100644
--- a/net/unix/Makefile
+++ b/net/unix/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_UNIX) += unix.o
unix-y := af_unix.o garbage.o
unix-$(CONFIG_SYSCTL) += sysctl_net_unix.o
+unix-$(CONFIG_BPF_SYSCALL) += unix_bpf.o
obj-$(CONFIG_UNIX_DIAG) += unix_diag.o
unix_diag-y := diag.o
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 966359b64a56..97dfb747e052 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -771,10 +771,18 @@ static const struct proto_ops unix_seqpacket_ops = {
.show_fdinfo = unix_show_fdinfo,
};
-static struct proto unix_proto = {
+static void unix_close(struct sock *sk, long timeout)
+{
+}
+
+struct proto unix_proto = {
.name = "UNIX",
.owner = THIS_MODULE,
.obj_size = sizeof(struct unix_sock),
+ .close = unix_close,
+#ifdef CONFIG_BPF_SYSCALL
+ .psock_update_sk_prot = unix_bpf_update_proto,
+#endif
};
static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
@@ -859,6 +867,7 @@ static int unix_release(struct socket *sock)
return 0;
unix_release_sock(sk, 0);
+ sk->sk_prot->close(sk, 0);
sock->sk = NULL;
return 0;
@@ -2957,6 +2966,7 @@ static int __init af_unix_init(void)
sock_register(&unix_family_ops);
register_pernet_subsys(&unix_net_ops);
+ unix_bpf_build_proto();
out:
return rc;
}
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
new file mode 100644
index 000000000000..8ce7651893f3
--- /dev/null
+++ b/net/unix/unix_bpf.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Cong Wang <cong.wang@...edance.com> */
+
+#include <linux/skmsg.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);
+}
--
2.25.1
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