From: Jakub Sitnicki <jakub@cloudflare.com>
To: Martin Lau <kafai@fb.com>, John Fastabend <john.fastabend@gmail.com>
Cc: "bpf\@vger.kernel.org" <bpf@vger.kernel.org>,
"netdev\@vger.kernel.org" <netdev@vger.kernel.org>,
"kernel-team\@cloudflare.com" <kernel-team@cloudflare.com>,
Eric Dumazet <edumazet@google.com>,
Lorenz Bauer <lmb@cloudflare.com>
Subject: Re: [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on lookup from syscall
Date: Tue, 14 Jan 2020 16:48:23 +0100 [thread overview]
Message-ID: <87blr6rqd4.fsf@cloudflare.com> (raw)
In-Reply-To: <5e1d328d760e_78752af1940225b4b7@john-XPS-13-9370.notmuch>
On Tue, Jan 14, 2020 at 04:16 AM CET, John Fastabend wrote:
> Martin Lau wrote:
>> On Fri, Jan 10, 2020 at 11:50:23AM +0100, Jakub Sitnicki wrote:
>> > Tooling that populates the SOCKMAP with sockets from user-space needs a way
>> > to inspect its contents. Returning the struct sock * that SOCKMAP holds to
>> > user-space is neither safe nor useful. An approach established by
>> > REUSEPORT_SOCKARRAY is to return a socket cookie (a unique identifier)
>> > instead.
>> >
>> > Since socket cookies are u64 values SOCKMAP needs to support such a value
>> > size for lookup to be possible. This requires special handling on update,
>> > though. Attempts to do a lookup on SOCKMAP holding u32 values will be met
>> > with ENOSPC error.
>> >
>> > Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
>> > ---
>
> [...]
>
>> > +static void *sock_map_lookup_sys(struct bpf_map *map, void *key)
>> > +{
>> > + struct sock *sk;
>> > +
>> > + WARN_ON_ONCE(!rcu_read_lock_held());
>> It seems unnecessary. It is only called by syscall.c which
>> holds the rcu_read_lock(). Other than that,
>>
>
> +1 drop it. The normal rcu annotations/splats should catch anything
> here.
Oh, okay. Thanks for pointing it out.
I noticed __sock_map_lookup_elem called from sock_map_lookup_sys has the
same WARN_ON_ONCE check. Looks like it can be cleaned up.
Granted, __sock_map_lookup_elem also gets invoked by sockmap BPF helpers
for redirecting (bpf_msg_redirect_map, bpf_sk_redirect_map). But we
always run sk_skb and sk_msg progs RCU read lock held.
next prev parent reply other threads:[~2020-01-14 15:48 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 10:50 [PATCH bpf-next v2 00/11] Extend SOCKMAP to store listening sockets Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 01/11] bpf, sk_msg: Don't reset saved sock proto on restore Jakub Sitnicki
2020-01-11 22:50 ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 02/11] net, sk_msg: Annotate lockless access to sk_prot on clone Jakub Sitnicki
2020-01-11 23:14 ` John Fastabend
2020-01-13 15:09 ` Jakub Sitnicki
2020-01-14 3:14 ` John Fastabend
2020-01-20 17:00 ` John Fastabend
2020-01-20 18:11 ` Jakub Sitnicki
2020-01-21 12:42 ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 03/11] net, sk_msg: Clear sk_user_data pointer on clone if tagged Jakub Sitnicki
2020-01-11 23:38 ` John Fastabend
2020-01-12 12:55 ` kbuild test robot
2020-01-13 20:15 ` Martin Lau
2020-01-14 16:04 ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 04/11] tcp_bpf: Don't let child socket inherit parent protocol ops on copy Jakub Sitnicki
2020-01-11 2:42 ` kbuild test robot
2020-01-11 3:02 ` kbuild test robot
2020-01-11 23:48 ` John Fastabend
2020-01-13 22:31 ` Jakub Sitnicki
2020-01-13 22:23 ` Martin Lau
2020-01-13 22:42 ` Jakub Sitnicki
2020-01-13 23:23 ` Martin Lau
2020-01-10 10:50 ` [PATCH bpf-next v2 05/11] bpf, sockmap: Allow inserting listening TCP sockets into sockmap Jakub Sitnicki
2020-01-11 23:59 ` John Fastabend
2020-01-13 15:48 ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 06/11] bpf, sockmap: Don't set up sockmap progs for listening sockets Jakub Sitnicki
2020-01-12 0:51 ` John Fastabend
2020-01-12 1:07 ` John Fastabend
2020-01-13 17:59 ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on lookup from syscall Jakub Sitnicki
2020-01-12 0:56 ` John Fastabend
2020-01-13 23:12 ` Martin Lau
2020-01-14 3:16 ` John Fastabend
2020-01-14 15:48 ` Jakub Sitnicki [this message]
2020-01-10 10:50 ` [PATCH bpf-next v2 08/11] bpf, sockmap: Let all kernel-land lookup values in SOCKMAP Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 09/11] bpf: Allow selecting reuseport socket from a SOCKMAP Jakub Sitnicki
2020-01-12 1:00 ` John Fastabend
2020-01-13 23:45 ` Martin Lau
2020-01-15 12:41 ` Jakub Sitnicki
2020-01-13 23:51 ` Martin Lau
2020-01-15 12:57 ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 10/11] selftests/bpf: Extend SK_REUSEPORT tests to cover SOCKMAP Jakub Sitnicki
2020-01-12 1:01 ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 11/11] selftests/bpf: Tests for SOCKMAP holding listening sockets Jakub Sitnicki
2020-01-12 1:06 ` John Fastabend
2020-01-13 15:58 ` Jakub Sitnicki
2020-01-11 0:18 ` [PATCH bpf-next v2 00/11] Extend SOCKMAP to store " Alexei Starovoitov
2020-01-11 22:47 ` John Fastabend
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