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net: sk_msg: Simplify sk_psock initialization

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Initializing psock->sk_proto and other saved callbacks is only
done in sk_psock_update_proto, after sk_psock_init has returned.
The logic for this is difficult to follow, and needlessly complex.

Instead, initialize psock->sk_proto whenever we allocate a new
psock. Additionally, assert the following invariants:

* The SK has no ULP: ULP does it's own finagling of sk->sk_prot
* sk_user_data is unused: we need it to store sk_psock

Protect our access to sk_user_data with sk_callback_lock, which
is what other users like reuseport arrays, etc. do.

The result is that an sk_psock is always fully initialized, and
that psock->sk_proto is always the "original" struct proto.
The latter allows us to use psock->sk_proto when initializing
IPv6 TCP / UDP callbacks for sockmap.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200821102948.21918-2-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer 2020-08-21 11:29:43 +01:00 • committed by Alexei Starovoitov
parent dca5612f8e
commit 7b219da43f
5 changed files with 41 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

14
net/core/sock_map.c
View file

@ -184,8 +184,6 @@ static int sock_map_init_proto(struct sock *sk, struct sk_psock *psock)
{
struct proto *prot;
sock_owned_by_me(sk);
switch (sk->sk_type) {
case SOCK_STREAM:
prot = tcp_bpf_get_proto(sk, psock);
@ -272,8 +270,8 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
}
} else {
psock = sk_psock_init(sk, map->numa_node);
if (!psock) {
ret = -ENOMEM;
if (IS_ERR(psock)) {
ret = PTR_ERR(psock);
goto out_progs;
}
}
@ -322,8 +320,8 @@ static int sock_map_link_no_progs(struct bpf_map *map, struct sock *sk)
if (!psock) {
psock = sk_psock_init(sk, map->numa_node);
if (!psock)
return -ENOMEM;
if (IS_ERR(psock))
return PTR_ERR(psock);
}
ret = sock_map_init_proto(sk, psock);
@ -478,8 +476,6 @@ static int sock_map_update_common(struct bpf_map *map, u32 idx,
return -EINVAL;
if (unlikely(idx >= map->max_entries))
return -E2BIG;
if (inet_csk_has_ulp(sk))
return -EINVAL;
link = sk_psock_init_link();
if (!link)
@ -855,8 +851,6 @@ static int sock_hash_update_common(struct bpf_map *map, void *key,
WARN_ON_ONCE(!rcu_read_lock_held());
if (unlikely(flags > BPF_EXIST))
return -EINVAL;
if (inet_csk_has_ulp(sk))
return -EINVAL;
link = sk_psock_init_link();
if (!link)