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[146.241.227.135]) by smtp.gmail.com with ESMTPSA id ch17-20020a5d5d11000000b0033d2ae84fafsm8346747wrb.52.2024.02.19.10.04.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Feb 2024 10:04:27 -0800 (PST) Message-ID: <278c26d6f4042dc6dadb9742afe11b7fa610f0b2.camel@redhat.com> Subject: Re: [PATCH net 03/13] mptcp: fix lockless access in subflow ULP diag From: Paolo Abeni To: Eric Dumazet , "Matthieu Baerts (NGI0)" Cc: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Jakub Kicinski , Davide Caratti , Shuah Khan , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org, Boris Pismenny , John Fastabend Date: Mon, 19 Feb 2024 19:04:15 +0100 In-Reply-To: References: <20240215-upstream-net-20240215-misc-fixes-v1-0-8c01a55d8f6a@kernel.org> <20240215-upstream-net-20240215-misc-fixes-v1-3-8c01a55d8f6a@kernel.org> Autocrypt: addr=pabeni@redhat.com; prefer-encrypt=mutual; keydata=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 7ZxN9ZsDL38qVIuFkSpgMZCiUHdxBC11J8nbBSLlpnc924UAyr5XrGA99 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 iWjoCy8L35zPqR5TV+f5WR5hTVCqmLHSgm1jxwKhPg9L+GfuE4d0SWd84y 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 sD2W1U7eyLdm/jCgticGDsRtweytsgCSYfbz0gdgUuL3EBYN3JLbAU+UZpy 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 (3.50.3-1.fc39) Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2024-02-19 at 18:35 +0100, Eric Dumazet wrote: > On Mon, Feb 19, 2024 at 6:21=E2=80=AFPM Eric Dumazet wrote: > >=20 > > On Thu, Feb 15, 2024 at 7:25=E2=80=AFPM Matthieu Baerts (NGI0) > > wrote: > > >=20 > > > From: Paolo Abeni > > >=20 > > > Since the introduction of the subflow ULP diag interface, the > > > dump callback accessed all the subflow data with lockless. > > >=20 > > > We need either to annotate all the read and write operation according= ly, > > > or acquire the subflow socket lock. Let's do latter, even if slower, = to > > > avoid a diffstat havoc. > > >=20 > > > Fixes: 5147dfb50832 ("mptcp: allow dumping subflow context to userspa= ce") > > > Cc: stable@vger.kernel.org > > > Signed-off-by: Paolo Abeni > > > Reviewed-by: Mat Martineau > > > Signed-off-by: Matthieu Baerts (NGI0) > > > --- > > > Notes: > > > - This patch modifies the existing ULP API. No better solutions hav= e > > > been found for -net, and there is some similar prior art, see > > > commit 0df48c26d841 ("tcp: add tcpi_bytes_acked to tcp_info"). > > >=20 > > > Please also note that TLS ULP Diag has likely the same issue. > > > To: Boris Pismenny > > > To: John Fastabend > > > --- > > > include/net/tcp.h | 2 +- > > > net/mptcp/diag.c | 6 +++++- > > > net/tls/tls_main.c | 2 +- > > > 3 files changed, 7 insertions(+), 3 deletions(-) > > >=20 > > > diff --git a/include/net/tcp.h b/include/net/tcp.h > > > index dd78a1181031..f6eba9652d01 100644 > > > --- a/include/net/tcp.h > > > +++ b/include/net/tcp.h > > > @@ -2506,7 +2506,7 @@ struct tcp_ulp_ops { > > > /* cleanup ulp */ > > > void (*release)(struct sock *sk); > > > /* diagnostic */ > > > - int (*get_info)(const struct sock *sk, struct sk_buff *skb); > > > + int (*get_info)(struct sock *sk, struct sk_buff *skb); > > > size_t (*get_info_size)(const struct sock *sk); > > > /* clone ulp */ > > > void (*clone)(const struct request_sock *req, struct sock *ne= wsk, > > > diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c > > > index a536586742f2..e57c5f47f035 100644 > > > --- a/net/mptcp/diag.c > > > +++ b/net/mptcp/diag.c > > > @@ -13,17 +13,19 @@ > > > #include > > > #include "protocol.h" > > >=20 > > > -static int subflow_get_info(const struct sock *sk, struct sk_buff *s= kb) > > > +static int subflow_get_info(struct sock *sk, struct sk_buff *skb) > > > { > > > struct mptcp_subflow_context *sf; > > > struct nlattr *start; > > > u32 flags =3D 0; > > > + bool slow; > > > int err; > > >=20 > > > start =3D nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP); > > > if (!start) > > > return -EMSGSIZE; > > >=20 > > > + slow =3D lock_sock_fast(sk); > > > rcu_read_lock(); > >=20 > > I am afraid lockdep is not happy with this change. > >=20 > > Paolo, we probably need the READ_ONCE() annotations after all. >=20 > Or perhaps something like the following would be enough. >=20 > diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c > index 6ff6f14674aa2941bc04c680bacd9f79fc65060d..7017dd60659dc7133318c1c82= e3f429bea3a5d57 > 100644 > --- a/net/mptcp/diag.c > +++ b/net/mptcp/diag.c > @@ -21,6 +21,9 @@ static int subflow_get_info(struct sock *sk, struct > sk_buff *skb) > bool slow; > int err; >=20 > + if (inet_sk_state_load(sk) =3D=3D TCP_LISTEN) > + return 0; > + > start =3D nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP); > if (!start) > return -EMSGSIZE; Thanks for the head-up. This later option looks preferable, to avoid quit a bit of noise with _ONCE annotation. Is there a syzkaller splat I could look at? if it landed on the ML, I missed it. Thanks! Paolo