On Thu, Feb 15, 2024 at 7:25 PM Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> wrote: > > From: Paolo Abeni <pabeni@xxxxxxxxxx> > > Since the introduction of the subflow ULP diag interface, the > dump callback accessed all the subflow data with lockless. > > We need either to annotate all the read and write operation accordingly, > or acquire the subflow socket lock. Let's do latter, even if slower, to > avoid a diffstat havoc. > > Fixes: 5147dfb50832 ("mptcp: allow dumping subflow context to userspace") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> > Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx> > Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> > --- > Notes: > - This patch modifies the existing ULP API. No better solutions have > been found for -net, and there is some similar prior art, see > commit 0df48c26d841 ("tcp: add tcpi_bytes_acked to tcp_info"). > > Please also note that TLS ULP Diag has likely the same issue. > To: Boris Pismenny <borisp@xxxxxxxxxx> > To: John Fastabend <john.fastabend@xxxxxxxxx> > --- > include/net/tcp.h | 2 +- > net/mptcp/diag.c | 6 +++++- > net/tls/tls_main.c | 2 +- > 3 files changed, 7 insertions(+), 3 deletions(-) > > 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 *newsk, > 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 <uapi/linux/mptcp.h> > #include "protocol.h" > > -static int subflow_get_info(const struct sock *sk, struct sk_buff *skb) > +static int subflow_get_info(struct sock *sk, struct sk_buff *skb) > { > struct mptcp_subflow_context *sf; > struct nlattr *start; > u32 flags = 0; > + bool slow; > int err; > > start = nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP); > if (!start) > return -EMSGSIZE; > > + slow = lock_sock_fast(sk); > rcu_read_lock(); I am afraid lockdep is not happy with this change. Paolo, we probably need the READ_ONCE() annotations after all.