From c63829182c37c2d6d0608976d15fa61ebebe9e6b Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sun, 4 Jul 2021 12:02:47 -0700 Subject: [PATCH] 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210704190252.11866-7-xiyou.wangcong@gmail.com --- MAINTAINERS | 1 + include/net/af_unix.h | 10 +++++++++ net/core/sock_map.c | 1 + net/unix/Makefile | 1 + net/unix/af_unix.c | 6 +++++- net/unix/unix_bpf.c | 47 +++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 65 insertions(+), 1 deletion(-) create mode 100644 net/unix/unix_bpf.c diff --git a/MAINTAINERS b/MAINTAINERS index 88449b7a4c95a..2c793df1d8736 100644 --- 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 diff --git a/include/net/af_unix.h b/include/net/af_unix.h index f42fdddecd417..cca645846af16 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 3c427e7e6df9c..ae5fa4338d9c1 100644 --- 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 54e58cc4f9450..20491825b4d0d 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 875eeaaddc07e..573253c5b5c2c 100644 --- 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 index 0000000000000..b1582a659427b --- /dev/null +++ b/net/unix/unix_bpf.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Cong Wang */ + +#include +#include +#include +#include + +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); +}