linux-stable.git/include/net/act_api.h, branch v6.1.185 Linux kernel stable tree net/sched: act_gact, act_police: range check the fallback control action 2026-08-19T15:16:28+00:00 Hyunjung Ko hj351016@gmail.com 2026-08-06T10:12:52+00:00 725efc2ab4a40affc4e285a2dc4896d103948a6c commit 883b56ae58fe657d8497806c7059646e9ba6dbd0 upstream. tcf_action_check_ctrlact() range checks the primary control action: if (!opcode) ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0; TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it cannot be set that way. But act_gact and act_police each carry a second, independent control action supplied by user space that never reaches that helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned verbatim from the action. In particular user space can store TC_ACT_CONSUMED, which is TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value range. That verdict tells every caller the action took ownership of the skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for it. The result is one leaked sk_buff plus its data buffer per packet traversing the filter, unbounded, for all traffic on the chain including kernel-generated packets. Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so with pval = 1 gact_determ() returns the fallback for every packet. act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and tcf_police_mtu_check() always passes. TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor reinsert action"), after both goto-chain guards were written: commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on fallback control action") and commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on fallback control action"). Neither guard was widened when the new verdict appeared. Factor the existing range test out of tcf_action_check_ctrlact() as tcf_action_valid() and apply it to both fallbacks. The helper cannot call tcf_action_check_ctrlact() directly because that also allocates a goto_chain, which is exactly what these two sites must not do. Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet. With this patch both configurations are rejected with -EINVAL and kmemleak reports none. Fixes: 720f22fed81b ("net: sched: refactor reinsert action") Cc: stable@vger.kernel.org # v5.3+ Signed-off-by: Hyunjung Ko <hj351016@gmail.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Tested-by: Victor Nogueira <victor@mojatatu.com> Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 883b56ae58fe657d8497806c7059646e9ba6dbd0 upstream.

tcf_action_check_ctrlact() range checks the primary control action:

	if (!opcode)
		ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0;

TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it
cannot be set that way. But act_gact and act_police each carry a second,
independent control action supplied by user space that never reaches that
helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject
TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned
verbatim from the action.

In particular user space can store TC_ACT_CONSUMED, which is
TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value
range. That verdict tells every caller the action took ownership of the
skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for it. The result is
one leaked sk_buff plus its data buffer per packet traversing the filter,
unbounded, for all traffic on the chain including kernel-generated
packets.

Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so
with pval = 1 gact_determ() returns the fallback for every packet.
act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and
tcf_police_mtu_check() always passes.

TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor
reinsert action"), after both goto-chain guards were written:
commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on
fallback control action") and
commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on
fallback control action"). Neither guard was widened when the new
verdict appeared.

Factor the existing range test out of tcf_action_check_ctrlact() as
tcf_action_valid() and apply it to both fallbacks. The helper cannot call
tcf_action_check_ctrlact() directly because that also allocates a
goto_chain, which is exactly what these two sites must not do.

Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte
skbuff_head_cache object plus its 704-byte data buffer per packet. With
this patch both configurations are rejected with -EINVAL and kmemleak
reports none.

Fixes: 720f22fed81b ("net: sched: refactor reinsert action")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Hyunjung Ko <hj351016@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/sched: act_api: use RCU with deferred freeing for action lifecycle 2026-06-19T11:37:08+00:00 Jamal Hadi Salim jhs@mojatatu.com 2026-05-31T16:08:12+00:00 1f1b98fea6b9ea30507d0f2fbff6750292d097e2 [ Upstream commit 5057e1aca011e51ef51498c940ef96f3d3e8a305 ] When NEWTFILTER and DELFILTER are run concurrently it is possible to create a race with an associated action. Let's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER: 0: mutex_lock() <-- holds the idr lock 0: rcu_read_lock() 0: p = idr_find(idr, index) <-- action p is valid (RCU protects IDR) 0: mutex_unlock() <-- releases the idr lock 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) <-- Action removed from IDR 1: mutex_unlock() <-- mutex released allowing us to delete the action 1: tcf_action_cleanup(p); kfree(p) <-- Kfrees p immediately, no deferral 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- ouch, UAF p points to freed memory This patch fixes the race condition between NEWTFILTER and DELFILTER by adding struct rcu_head to tc_action used in the deferral and introducing a call_rcu() in the delete path to defer the final kfree(). Note: this is a revert of commit d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") but also modernization/simplification to directly use kfree_rcu(). Let's illustrate the new restored code path: 0: rcu_read_lock() 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held 1: idr_remove(idr, index) 1: mutex_unlock() 1: call_rcu(&p->tcfa_rcu, tcf_action_rcu_free) <-- defer kfree after grace period 0: p = idr_find(idr, index) 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- fails, refcnt already 0 1: rcu_read_unlock() <-- release so freeing can run after grace period After CPU1 calls idr_remove(), the object is no longer reachable through the IDR. CPU0's subsequent idr_find() will return NULL, and even if it still held a stale pointer, the immediate kfree() is now deferred until after the RCU grace period, so no UAF can occur. Fixes: d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") Suggested-by: Jakub Kicinski <kuba@kernel.org> Reported-by: Kyle Zeng <kylebot@openai.com> Tested-by: Victor Nogueira <victor@mojatatu.com> Tested-by: syzbot@syzkaller.appspotmail.com Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Tested-by: Kyle Zeng <kylebot@openai.com> Reviewed-by: Pedro Tammela <pctammela@mojatatu.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Victor Nogueira <victor@mojatatu.com> Link: https://patch.msgid.link/20260531160812.68020-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 5057e1aca011e51ef51498c940ef96f3d3e8a305 ]

When NEWTFILTER and DELFILTER are run concurrently it is possible to create a
race with an associated action.

Let's illustrate with CPU0 running NEWTFILTER and CPU1 running DELFILTER:

 0: mutex_lock() <-- holds the idr lock
 0: rcu_read_lock()
 0: p = idr_find(idr, index) <-- action p is valid (RCU protects IDR)
 0: mutex_unlock() <-- releases the idr lock
 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held
 1: idr_remove(idr, index) <-- Action removed from IDR
 1: mutex_unlock() <-- mutex released allowing us to delete the action
 1: tcf_action_cleanup(p); kfree(p) <-- Kfrees p immediately, no deferral
 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- ouch, UAF p points to freed memory

This patch fixes the race condition between NEWTFILTER and DELFILTER by
adding struct rcu_head to tc_action used in the deferral and introducing a
call_rcu() in the delete path to defer the final kfree().

Note: this is a revert of commit d7fb60b9cafb ("net_sched: get rid of tcfa_rcu")
but also modernization/simplification to directly use kfree_rcu().

Let's illustrate the new restored code path:

 0: rcu_read_lock()
 1: refcount_dec_and_mutex_lock() <-- refcnt 1->0, mutex held
 1: idr_remove(idr, index)
 1: mutex_unlock()
 1: call_rcu(&p->tcfa_rcu, tcf_action_rcu_free) <-- defer kfree after grace period
 0: p = idr_find(idr, index)
 0: refcount_inc_not_zero(&p->tcfa_refcnt) <-- fails, refcnt already 0
 1: rcu_read_unlock() <-- release so freeing can run after grace period

After CPU1 calls idr_remove(), the object is no longer reachable through the IDR.
CPU0's subsequent idr_find() will return NULL, and even if it still held a
stale pointer, the immediate kfree() is now deferred until after the RCU grace
period, so no UAF can occur.

Fixes: d7fb60b9cafb ("net_sched: get rid of tcfa_rcu")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Reported-by: Kyle Zeng <kylebot@openai.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Kyle Zeng <kylebot@openai.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20260531160812.68020-1-jhs@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks 2026-03-25T10:03:02+00:00 Victor Nogueira victor@mojatatu.com 2026-02-25T13:43:48+00:00 fb3c380a54e33d1fd272cc342faa906d787d7ef1 commit 11cb63b0d1a0685e0831ae3c77223e002ef18189 upstream. As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/ Reported-by: GangMin Kim <km.kim1503@gmail.com> Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") CC: stable@vger.kernel.org Signed-off-by: Victor Nogueira <victor@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://patch.msgid.link/20260225134349.1287037-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 11cb63b0d1a0685e0831ae3c77223e002ef18189 upstream.

As Paolo said earlier [1]:

"Since the blamed commit below, classify can return TC_ACT_CONSUMED while
the current skb being held by the defragmentation engine. As reported by
GangMin Kim, if such packet is that may cause a UaF when the defrag engine
later on tries to tuch again such packet."

act_ct was never meant to be used in the egress path, however some users
are attaching it to egress today [2]. Attempting to reach a middle
ground, we noticed that, while most qdiscs are not handling
TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we
address the issue by only allowing act_ct to bind to clsact/ingress
qdiscs and shared blocks. That way it's still possible to attach act_ct to
egress (albeit only with clsact).

[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/
[2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/

Reported-by: GangMin Kim <km.kim1503@gmail.com>
Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags")
CC: stable@vger.kernel.org
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260225134349.1287037-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: sched: act: move global static variable net_id to tc_action_ops 2022-09-09T07:24:41+00:00 Zhengchao Shao shaozhengchao@huawei.com 2022-09-08T04:14:33+00:00 acd0a7ab6334f35c3720120d53f79eb8e9b3ac2e Each tc action module has a corresponding net_id, so put net_id directly into the structure tc_action_ops. Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Each tc action module has a corresponding net_id, so put net_id directly
into the structure tc_action_ops.

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/sched: act_api: Add extack to offload_act_setup() callback 2022-04-08T12:45:43+00:00 Ido Schimmel idosch@nvidia.com 2022-04-07T07:35:22+00:00 c2ccf84ecb715bb81dc7f51e69d680a95bf055ae The callback is used by various actions to populate the flow action structure prior to offload. Pass extack to this callback so that the various actions will be able to report accurate error messages to user space. Signed-off-by: Ido Schimmel <idosch@nvidia.com> Reviewed-by: Petr Machata <petrm@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The callback is used by various actions to populate the flow action
structure prior to offload. Pass extack to this callback so that the
various actions will be able to report accurate error messages to user
space.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
flow_offload: validate flags of filter and actions 2021-12-19T14:08:48+00:00 Baowen Zheng baowen.zheng@corigine.com 2021-12-17T18:16:28+00:00 c86e0209dc7725c91583e3c0c78c3da6a28daeb4 Add process to validate flags of filter and actions when adding a tc filter. We need to prevent adding filter with flags conflicts with its actions. Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com> Signed-off-by: Louis Peens <louis.peens@corigine.com> Signed-off-by: Simon Horman <simon.horman@corigine.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Add process to validate flags of filter and actions when adding
a tc filter.

We need to prevent adding filter with flags conflicts with its actions.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
flow_offload: add reoffload process to update hw_count 2021-12-19T14:08:48+00:00 Baowen Zheng baowen.zheng@corigine.com 2021-12-17T18:16:27+00:00 13926d19a11e303f12571df61b7bb64f17cb4561 Add reoffload process to update hw_count when driver is inserted or removed. We will delete the action if it is with skip_sw flag and not offloaded to any hardware in reoffload process. When reoffloading actions, we still offload the actions that are added independent of filters. Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com> Signed-off-by: Louis Peens <louis.peens@corigine.com> Signed-off-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Add reoffload process to update hw_count when driver
is inserted or removed.

We will delete the action if it is with skip_sw flag and
not offloaded to any hardware in reoffload process.

When reoffloading actions, we still offload the actions
that are added independent of filters.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
flow_offload: add process to update action stats from hardware 2021-12-19T14:08:48+00:00 Baowen Zheng baowen.zheng@corigine.com 2021-12-17T18:16:25+00:00 c7a66f8d8a946edafb38150480145ab9801e4e52 When collecting stats for actions update them using both hardware and software counters. Stats update process should not run in context of preempt_disable. Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com> Signed-off-by: Louis Peens <louis.peens@corigine.com> Signed-off-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
When collecting stats for actions update them using both
hardware and software counters.

Stats update process should not run in context of preempt_disable.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
flow_offload: add skip_hw and skip_sw to control if offload the action 2021-12-19T14:08:48+00:00 Baowen Zheng baowen.zheng@corigine.com 2021-12-17T18:16:23+00:00 7adc576512110ef32b0424a727ee1d04359fc205 We add skip_hw and skip_sw for user to control if offload the action to hardware. We also add in_hw_count for user to indicate if the action is offloaded to any hardware. Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com> Signed-off-by: Simon Horman <simon.horman@corigine.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We add skip_hw and skip_sw for user to control if offload the action
to hardware.

We also add in_hw_count for user to indicate if the action is offloaded
to any hardware.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
flow_offload: add ops to tc_action_ops for flow action setup 2021-12-19T14:08:48+00:00 Baowen Zheng baowen.zheng@corigine.com 2021-12-17T18:16:21+00:00 c54e1d920f04d528ab558f09326a78d2ae59e323 Add a new ops to tc_action_ops for flow action setup. Refactor function tc_setup_flow_action to use this new ops. We make this change to facilitate to add standalone action module. We will also use this ops to offload action independent of filter in following patch. Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com> Signed-off-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Add a new ops to tc_action_ops for flow action setup.

Refactor function tc_setup_flow_action to use this new ops.

We make this change to facilitate to add standalone action module.

We will also use this ops to offload action independent of filter
in following patch.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>