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Vladimir Oltean 34d35b4edb net/sched: act_api: deny mismatched skip_sw/skip_hw flags for actions created by classifiers 
tcf_action_init() has logic for checking mismatches between action and
filter offload flags (skip_sw/skip_hw). AFAIU, this is intended to run
on the transition between the new tc_act_bind(flags) returning true (aka
now gets bound to classifier) and tc_act_bind(act->tcfa_flags) returning
false (aka action was not bound to classifier before). Otherwise, the
check is skipped.

For the case where an action is not standalone, but rather it was
created by a classifier and is bound to it, tcf_action_init() skips the
check entirely, and this means it allows mismatched flags to occur.

Taking the matchall classifier code path as an example (with mirred as
an action), the reason is the following:

 1 | mall_change()
 2 | -> mall_replace_hw_filter()
 3 |   -> tcf_exts_validate_ex()
 4 |      -> flags |= TCA_ACT_FLAGS_BIND;
 5 |      -> tcf_action_init()
 6 |         -> tcf_action_init_1()
 7 |            -> a_o->init()
 8 |               -> tcf_mirred_init()
 9 |                  -> tcf_idr_create_from_flags()
10 |                     -> tcf_idr_create()
11 |                        -> p->tcfa_flags = flags;
12 |         -> tc_act_bind(flags))
13 |         -> tc_act_bind(act->tcfa_flags)

When invoked from tcf_exts_validate_ex() like matchall does (but other
classifiers validate their extensions as well), tcf_action_init() runs
in a call path where "flags" always contains TCA_ACT_FLAGS_BIND (set by
line 4). So line 12 is always true, and line 13 is always true as well.
No transition ever takes place, and the check is skipped.

The code was added in this form in commit c86e0209dc ("flow_offload:
validate flags of filter and actions"), but I'm attributing the blame
even earlier in that series, to when TCA_ACT_FLAGS_SKIP_HW and
TCA_ACT_FLAGS_SKIP_SW were added to the UAPI.

Following the development process of this change, the check did not
always exist in this form. A change took place between v3 [1] and v4 [2],
AFAIU due to review feedback that it doesn't make sense for action flags
to be different than classifier flags. I think I agree with that
feedback, but it was translated into code that omits enforcing this for
"classic" actions created at the same time with the filters themselves.

There are 3 more important cases to discuss. First there is this command:

$ tc qdisc add dev eth0 clasct
$ tc filter add dev eth0 ingress matchall skip_sw \
	action mirred ingress mirror dev eth1

which should be allowed, because prior to the concept of dedicated
action flags, it used to work and it used to mean the action inherited
the skip_sw/skip_hw flags from the classifier. It's not a mismatch.

Then we have this command:

$ tc qdisc add dev eth0 clasct
$ tc filter add dev eth0 ingress matchall skip_sw \
	action mirred ingress mirror dev eth1 skip_hw

where there is a mismatch and it should be rejected.

Finally, we have:

$ tc qdisc add dev eth0 clasct
$ tc filter add dev eth0 ingress matchall skip_sw \
	action mirred ingress mirror dev eth1 skip_sw

where the offload flags coincide, and this should be treated the same as
the first command based on inheritance, and accepted.

[1]: https://lore.kernel.org/netdev/20211028110646.13791-9-simon.horman@corigine.com/
[2]: https://lore.kernel.org/netdev/20211118130805.23897-10-simon.horman@corigine.com/
Fixes: 7adc576512 ("flow_offload: add skip_hw and skip_sw to control if offload the action")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20241017161049.3570037-1-vladimir.oltean@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-10-23 11:31:27 +02:00
arch powerpc fixes for 6.12 #4 2024-10-12 17:16:21 -07:00
block block-6.12-20241004 2024-10-04 10:43:44 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation No contributions from subtrees. 2024-10-17 09:31:18 -07:00
drivers net: usb: usbnet: fix name regression 2024-10-22 13:24:26 +02:00
fs for-6.12-rc3-tag 2024-10-16 09:30:20 -07:00
include net: fix races in netdev_tx_sent_queue()/dev_watchdog() 2024-10-21 12:54:25 +02:00
init cfi: encode cfi normalized integers + kasan/gcov bug in Kconfig 2024-09-26 21:27:27 +02:00
io_uring io_uring/rw: allow pollable non-blocking attempts for !FMODE_NOWAIT 2024-10-06 20:58:53 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel No contributions from subtrees. 2024-10-17 09:31:18 -07:00
lib slab fixes for 6.12-rc1 2024-10-04 12:05:39 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm: zswap: delete comments for "value" member of 'struct zswap_entry'. 2024-10-09 12:47:19 -07:00
net net/sched: act_api: deny mismatched skip_sw/skip_hw flags for actions created by classifiers 2024-10-23 11:31:27 +02:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts kbuild: deb-pkg: Remove blank first line from maint scripts 2024-10-07 02:36:38 +09:00
security bcachefs: do not use PF_MEMALLOC_NORECLAIM 2024-10-09 12:47:18 -07:00
sound sound fixes for 6.12-rc2 2024-10-04 11:29:46 -07:00
tools No contributions from subtrees. 2024-10-17 09:31:18 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt x86: 2024-09-28 09:20:14 -07:00
.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
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.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
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Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add samples/pktgen to NETWORKING [GENERAL] 2024-10-20 09:41:10 -05:00
Makefile Linux 6.12-rc3 2024-10-13 14:33:32 -07:00
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.