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Vladimir Oltean 67814ea2d1 net: dsa: restore dsa_software_vlan_untag() ability to operate on VLAN-untagged traffic 
[ Upstream commit 16f027cd40 ]

Robert Hodaszi reports that locally terminated traffic towards
VLAN-unaware bridge ports is broken with ocelot-8021q. He is describing
the same symptoms as for commit 1f9fc48fd3 ("net: dsa: sja1105: fix
reception from VLAN-unaware bridges").

For context, the set merged as "VLAN fixes for Ocelot driver":
https://lore.kernel.org/netdev/20240815000707.2006121-1-vladimir.oltean@nxp.com/

was developed in a slightly different form earlier this year, in January.
Initially, the switch was unconditionally configured to set OCELOT_ES0_TAG
when using ocelot-8021q, regardless of port operating mode.

This led to the situation where VLAN-unaware bridge ports would always
push their PVID - see ocelot_vlan_unaware_pvid() - a negligible value
anyway - into RX packets. To strip this in software, we would have needed
DSA to know what private VID the switch chose for VLAN-unaware bridge
ports, and pushed into the packets. This was implemented downstream, and
a remnant of it remains in the form of a comment mentioning
ds->ops->get_private_vid(), as something which would maybe need to be
considered in the future.

However, for upstream, it was deemed inappropriate, because it would
mean introducing yet another behavior for stripping VLAN tags from
VLAN-unaware bridge ports, when one already existed (ds->untag_bridge_pvid).
The latter has been marked as obsolete along with an explanation why it
is logically broken, but still, it would have been confusing.

So, for upstream, felix_update_tag_8021q_rx_rule() was developed, which
essentially changed the state of affairs from "Felix with ocelot-8021q
delivers all packets as VLAN-tagged towards the CPU" into "Felix with
ocelot-8021q delivers all packets from VLAN-aware bridge ports towards
the CPU". This was done on the premise that in VLAN-unaware mode,
there's nothing useful in the VLAN tags, and we can avoid introducing
ds->ops->get_private_vid() in the DSA receive path if we configure the
switch to not push those VLAN tags into packets in the first place.

Unfortunately, and this is when the trainwreck started, the selftests
developed initially and posted with the series were not re-ran.
dsa_software_vlan_untag() was initially written given the assumption
that users of this feature would send _all_ traffic as VLAN-tagged.
It was only partially adapted to the new scheme, by removing
ds->ops->get_private_vid(), which also used to be necessary in
standalone ports mode.

Where the trainwreck became even worse is that I had a second opportunity
to think about this, when the dsa_software_vlan_untag() logic change
initially broke sja1105, in commit 1f9fc48fd3 ("net: dsa: sja1105: fix
reception from VLAN-unaware bridges"). I did not connect the dots that
it also breaks ocelot-8021q, for pretty much the same reason that not
all received packets will be VLAN-tagged.

To be compatible with the optimized Felix control path which runs
felix_update_tag_8021q_rx_rule() to only push VLAN tags when useful (in
VLAN-aware mode), we need to restore the old dsa_software_vlan_untag()
logic. The blamed commit introduced the assumption that
dsa_software_vlan_untag() will see only VLAN-tagged packets, assumption
which is false. What corrupts RX traffic is the fact that we call
skb_vlan_untag() on packets which are not VLAN-tagged in the first
place.

Fixes: 93e4649efa ("net: dsa: provide a software untagging function on RX for VLAN-aware bridges")
Reported-by: Robert Hodaszi <robert.hodaszi@digi.com>
Closes: https://lore.kernel.org/netdev/20241215163334.615427-1-robert.hodaszi@digi.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241216135059.1258266-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-12-27 14:02:05 +01:00
arch s390/mm: Consider KMSAN modules metadata for paging levels 2024-12-27 14:01:59 +01:00
block block: Fix potential deadlock while freezing queue and acquiring sysfs_lock 2024-12-19 18:13:22 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: ecdsa - Avoid signed integer overflow on signature decoding 2024-12-14 20:03:36 +01:00
Documentation Documentation: networking: Add a caveat to nexthop_compat_mode sysctl 2024-12-19 18:13:16 +01:00
drivers can: m_can: fix missed interrupts with m_can_pci 2024-12-27 14:02:05 +01:00
fs ksmbd: fix broken transfers when exceeding max simultaneous operations 2024-12-27 14:02:03 +01:00
include sched/dlserver: Fix dlserver double enqueue 2024-12-27 14:01:59 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-05 14:02:45 +01:00
io_uring io_uring/tctx: work around xa_store() allocation error issue 2024-12-14 20:04:10 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel sched/dlserver: Fix dlserver time accounting 2024-12-27 14:01:59 +01:00
lib timekeeping: Remove CONFIG_DEBUG_TIMEKEEPING 2024-12-14 20:04:16 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm memcg: slub: fix SUnreclaim for post charged objects 2024-12-19 18:13:01 +01:00
net net: dsa: restore dsa_software_vlan_untag() ability to operate on VLAN-untagged traffic 2024-12-27 14:02:05 +01:00
rust rust: kbuild: set bindgen's Rust target version 2024-12-19 18:13:22 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 20:03:46 +01:00
scripts setlocalversion: work around "git describe" performance 2024-12-14 20:04:10 +01:00
security apparmor: test: Fix memory leak for aa_unpack_strdup() 2024-12-05 14:02:46 +01:00
sound firmware: arm_scmi: Fix i.MX build dependency 2024-12-27 14:01:57 +01:00
tools selftests: openvswitch: fix tcpdump execution 2024-12-27 14:02:05 +01:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: update location of media main tree 2024-12-05 14:02:42 +01:00
Makefile Linux 6.12.6 2024-12-19 18:13:24 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.