linux.git/net/kcm, branch v6.5

sock: Remove ->sendpage*() in favour of sendmsg(MSG_SPLICE_PAGES)

2023-06-24T22:50:13+00:00

Remove ->sendpage() and ->sendpage_locked().  sendmsg() with
MSG_SPLICE_PAGES should be used instead.  This allows multiple pages and
multipage folios to be passed through.

Signed-off-by: David Howells 
Acked-by: Marc Kleine-Budde  # for net/can
cc: Jens Axboe 
cc: Matthew Wilcox 
cc: linux-afs@lists.infradead.org
cc: mptcp@lists.linux.dev
cc: rds-devel@oss.oracle.com
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
Link: https://lore.kernel.org/r/20230623225513.2732256-16-dhowells@redhat.com
Signed-off-by: Jakub Kicinski

kcm: Fix unnecessary psock unreservation.

2023-06-17T07:08:27+00:00

kcm_write_msgs() calls unreserve_psock() to release its hold on the
underlying TCP socket if it has run out of things to transmit, but if we
have nothing in the write queue on entry (e.g. because someone did a
zero-length sendmsg), we don't actually go into the transmission loop and
as a consequence don't call reserve_psock().

Fix this by skipping the call to unreserve_psock() if we didn't reserve a
psock.

Fixes: c31a25e1db48 ("kcm: Send multiple frags in one sendmsg()")
Reported-by: syzbot+dd1339599f1840e4cc65@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000a61ffe05fe0c3d08@google.com/
Signed-off-by: David Howells 
Tested-by: syzbot+dd1339599f1840e4cc65@syzkaller.appspotmail.com
cc: Tom Herbert 
cc: Tom Herbert 
cc: Jens Axboe 
cc: Matthew Wilcox 
Link: https://lore.kernel.org/r/20787.1686828722@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski

kcm: Send multiple frags in one sendmsg()

2023-06-13T04:13:23+00:00

Rewrite the AF_KCM transmission loop to send all the fragments in a single
skb or frag_list-skb in one sendmsg() with MSG_SPLICE_PAGES set.  The list
of fragments in each skb is conveniently a bio_vec[] that can just be
attached to a BVEC iter.

Note: I'm working out the size of each fragment-skb by adding up bv_len for
all the bio_vecs in skb->frags[] - but surely this information is recorded
somewhere?  For the skbs in head->frag_list, this is equal to
skb->data_len, but not for the head.  head->data_len includes all the tail
frags too.

Signed-off-by: David Howells 
cc: Tom Herbert 
cc: Tom Herbert 
cc: Jens Axboe 
cc: Matthew Wilcox 
Signed-off-by: Jakub Kicinski

kcm: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

2023-06-13T04:13:23+00:00

When transmitting data, call down into the transport socket using sendmsg
with MSG_SPLICE_PAGES to indicate that content should be spliced rather
than using sendpage.

Signed-off-by: David Howells 
cc: Tom Herbert 
cc: Tom Herbert 
cc: Jens Axboe 
cc: Matthew Wilcox 
Signed-off-by: Jakub Kicinski

kcm: Use splice_eof() to flush

2023-06-09T02:40:31+00:00

Allow splice to undo the effects of MSG_MORE after prematurely ending a
splice/sendfile due to getting an EOF condition (->splice_read() returned
0) after splice had called sendmsg() with MSG_MORE set when the user didn't
set MSG_MORE.

Suggested-by: Linus Torvalds 
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/
Signed-off-by: David Howells 
cc: Tom Herbert 
cc: Tom Herbert 
cc: Cong Wang 
cc: Jens Axboe 
cc: Matthew Wilcox 
Signed-off-by: Jakub Kicinski

kcm: Convert kcm_sendpage() to use MSG_SPLICE_PAGES

2023-06-06T03:51:56+00:00

Convert kcm_sendpage() to use sendmsg() with MSG_SPLICE_PAGES rather than
directly splicing in the pages itself.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Signed-off-by: David Howells 
cc: Tom Herbert 
cc: Tom Herbert 
cc: Cong Wang 
cc: Jens Axboe 
cc: Matthew Wilcox 
Signed-off-by: Jakub Kicinski

kcm: Support MSG_SPLICE_PAGES

2023-06-06T03:51:56+00:00

Make AF_KCM sendmsg() support MSG_SPLICE_PAGES.  This causes pages to be
spliced from the source iterator if possible.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Signed-off-by: David Howells 
cc: Tom Herbert 
cc: Tom Herbert 
cc: Cong Wang 
cc: Jens Axboe 
cc: Matthew Wilcox 
Signed-off-by: Jakub Kicinski

net/sock: Introduce trace_sk_data_ready()

2023-01-23T11:26:50+00:00

As suggested by Cong, introduce a tracepoint for all ->sk_data_ready()
callback implementations.  For example:

<...>
  iperf-609  [002] .....  70.660425: sk_data_ready: family=2 protocol=6 func=sock_def_readable
  iperf-609  [002] .....  70.660436: sk_data_ready: family=2 protocol=6 func=sock_def_readable
<...>

Suggested-by: Cong Wang 
Signed-off-by: Peilin Ye 
Signed-off-by: David S. Miller

kcm: close race conditions on sk_receive_queue

2022-11-15T11:42:26+00:00

sk->sk_receive_queue is protected by skb queue lock, but for KCM
sockets its RX path takes mux->rx_lock to protect more than just
skb queue. However, kcm_recvmsg() still only grabs the skb queue
lock, so race conditions still exist.

We can teach kcm_recvmsg() to grab mux->rx_lock too but this would
introduce a potential performance regression as struct kcm_mux can
be shared by multiple KCM sockets.

So we have to enforce skb queue lock in requeue_rx_msgs() and handle
skb peek case carefully in kcm_wait_data(). Fortunately,
skb_recv_datagram() already handles it nicely and is widely used by
other sockets, we can just switch to skb_recv_datagram() after
getting rid of the unnecessary sock lock in kcm_recvmsg() and
kcm_splice_read(). Side note: SOCK_DONE is not used by KCM sockets,
so it is safe to get rid of this check too.

I ran the original syzbot reproducer for 30 min without seeing any
issue.

Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Reported-by: syzbot+278279efdd2730dd14bf@syzkaller.appspotmail.com
Reported-by: shaozhengchao 
Cc: Paolo Abeni 
Cc: Tom Herbert 
Signed-off-by: Cong Wang 
Link: https://lore.kernel.org/r/20221114005119.597905-1-xiyou.wangcong@gmail.com
Signed-off-by: Paolo Abeni

kcm: do not sense pfmemalloc status in kcm_sendpage()

2022-10-27T18:25:13+00:00

Similar to changes done in TCP in blamed commit.
We should not sense pfmemalloc status in sendpage() methods.

Fixes: 326140063946 ("tcp: TX zerocopy should not sense pfmemalloc status")
Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20221027040637.1107703-1-edumazet@google.com
Signed-off-by: Jakub Kicinski