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af_unix: implement ->psock_update_sk_prot()
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@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com>
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Cong Wang
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Apr 19, 2021
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// SPDX-License-Identifier: GPL-2.0 | ||
/* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */ | ||
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#include <linux/skmsg.h> | ||
#include <net/sock.h> | ||
#include <net/af_unix.h> | ||
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static struct proto *unix_prot_saved __read_mostly; | ||
static DEFINE_SPINLOCK(unix_prot_lock); | ||
static struct proto unix_bpf_prot; | ||
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static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base) | ||
{ | ||
*prot = *base; | ||
prot->close = sock_map_close; | ||
} | ||
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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); | ||
} | ||
} | ||
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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; | ||
} | ||
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unix_bpf_check_needs_rebuild(psock->sk_proto); | ||
WRITE_ONCE(sk->sk_prot, &unix_bpf_prot); | ||
return 0; | ||
} | ||
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void __init unix_bpf_build_proto(void) | ||
{ | ||
unix_bpf_rebuild_protos(&unix_bpf_prot, &unix_proto); | ||
} |