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/MAINTAINERS b/MAINTAINERS
index 88449b7a4c95a3eb0fcde3db724c8e70fd529744..2c793df1d87360f7231fd13f3d3e27d628488944 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10277,6 +10277,7 @@ 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
 
 LANDLOCK SECURITY MODULE
 M:     Mickaël Salaün <mic@digikod.net>

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index f42fdddecd417dcf2660d94a79796f912f31db88..cca645846af160465877275cb3c32292da23cda7 100644 (file)
--- 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 3c427e7e6df9cfe1e5527ac95b0e654f1fd4deb3..ae5fa4338d9c1a751e4d7df7c26426f55568cf0b 100644 (file)
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1517,6 +1517,7 @@ 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 54e58cc4f94502d9d888f60527a40bd2fd86b748..20491825b4d0da5bfa9b2b3352125360956b7f34 100644 (file)
--- 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 875eeaaddc07ecf69bfc928a6b615f03bbd55b1b..573253c5b5c2c2bf81a11c4163250bf1cf55f158 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -788,11 +788,14 @@ static void unix_close(struct sock *sk, long timeout)
         */
 }
 
-static struct proto unix_proto = {
+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)
@@ -2973,6 +2976,7 @@ 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 (file)
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);
+}