linux/include
Matthias Schiffer fa5d019c56 net: l2tp: reduce log level of messages in receive path, add counter instead
commit 3e59e88567 upstream.

Commit 5ee759cda5 ("l2tp: use standard API for warning log messages")
changed a number of warnings about invalid packets in the receive path
so that they are always shown, instead of only when a special L2TP debug
flag is set. Even with rate limiting these warnings can easily cause
significant log spam - potentially triggered by a malicious party
sending invalid packets on purpose.

In addition these warnings were noticed by projects like Tunneldigger [1],
which uses L2TP for its data path, but implements its own control
protocol (which is sufficiently different from L2TP data packets that it
would always be passed up to userspace even with future extensions of
L2TP).

Some of the warnings were already redundant, as l2tp_stats has a counter
for these packets. This commit adds one additional counter for invalid
packets that are passed up to userspace. Packets with unknown session are
not counted as invalid, as there is nothing wrong with the format of
these packets.

With the additional counter, all of these messages are either redundant
or benign, so we reduce them to pr_debug_ratelimited().

[1] https://github.com/wlanslovenija/tunneldigger/issues/160

Fixes: 5ee759cda5 ("l2tp: use standard API for warning log messages")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-17 17:06:11 +01:00
..
acpi ACPICA: Fix exception code class checks 2021-03-04 11:37:24 +01:00
asm-generic vmlinux.lds.h: Define SANTIZER_DISCARDS with CONFIG_GCOV_KERNEL=y 2021-03-04 11:37:19 +01:00
clocksource
crypto crypto - shash: reduce minimum alignment of shash_desc structure 2021-03-09 11:11:13 +01:00
drm drm/dp/mst: Export drm_dp_get_vc_payload_bw() 2021-02-10 09:29:18 +01:00
dt-bindings ASoC: dt-bindings: lpass: Fix and common up lpass dai ids 2021-02-03 23:28:46 +01:00
keys
kunit kunit: fix display of failed expectations for strings 2020-11-10 13:45:15 -07:00
kvm ARM: 2020-10-23 11:17:56 -07:00
linux net: check if protocol extracted by virtio_net_hdr_set_proto is correct 2021-03-17 17:06:11 +01:00
math-emu
media media: v4l2-fwnode: v4l2_fwnode_endpoint_parse caller must init vep argument 2020-12-30 11:53:11 +01:00
memory
misc
net Bluetooth: Add new HCI_QUIRK_NO_SUSPEND_NOTIFIER quirk 2021-03-07 12:34:10 +01:00
pcmcia
ras
rdma RDMA: Lift ibdev_to_node from rds to common code 2021-02-26 10:12:59 +01:00
scsi scsi: libiscsi: Fix NOP race condition 2020-11-16 22:32:50 -05:00
soc net: dsa: felix: implement port flushing on .phylink_mac_link_down 2021-02-17 11:02:27 +01:00
sound ALSA: hda: intel-nhlt: verify config type 2021-03-09 11:11:14 +01:00
target
trace trace: fix potenial dangerous pointer 2020-11-25 13:03:44 +01:00
uapi net: l2tp: reduce log level of messages in receive path, add counter instead 2021-03-17 17:06:11 +01:00
vdso
video gpu: ipu-v3: remove unused functions 2020-10-26 10:42:38 +01:00
xen Xen/gntdev: correct error checking in gntdev_map_grant_pages() 2021-02-23 15:53:24 +01:00