kernel.git/net/sched/act_api.c, branch linux-6.10.y

net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc()

2024-06-18T10:28:01Z

syzbot found hanging tasks waiting on rtnl_lock [1] A reproducer is available in the syzbot bug. When a request to add multiple actions with the same index is sent, the second request will block forever on the first request. This holds rtnl_lock, and causes tasks to hang. Return -EAGAIN to prevent infinite looping, while keeping documented behavior. [1] INFO: task kworker/1:0:5088 blocked for more than 143 seconds. Not tainted 6.9.0-rc4-syzkaller-00173-g3cdb45594619 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:0 state:D stack:23744 pid:5088 tgid:5088 ppid:2 flags:0x00004000 Workqueue: events_power_efficient reg_check_chans_work Call Trace: context_switch kernel/sched/core.c:5409 [inline] __schedule+0xf15/0x5d00 kernel/sched/core.c:6746 __schedule_loop kernel/sched/core.c:6823 [inline] schedule+0xe7/0x350 kernel/sched/core.c:6838 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6895 __mutex_lock_common kernel/locking/mutex.c:684 [inline] __mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752 wiphy_lock include/net/cfg80211.h:5953 [inline] reg_leave_invalid_chans net/wireless/reg.c:2466 [inline] reg_check_chans_work+0x10a/0x10e0 net/wireless/reg.c:2481 Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action") Reported-by: syzbot+b87c222546179f4513a7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b87c222546179f4513a7 Signed-off-by: David Ruth Reviewed-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20240614190326.1349786-1-druth@chromium.org Signed-off-by: Paolo Abeni

net/sched: Load modules via their alias

2024-02-02T18:57:55Z

The cls_,sch_,act_ modules may be loaded lazily during network configuration but without user's awareness and control. Switch the lazy loading from canonical module names to a module alias. This allows finer control over lazy loading, the precedent from commit 7f78e0351394 ("fs: Limit sys_mount to only request filesystem modules.") explains it already: Using aliases means user space can control the policy of which filesystem^W net/sched modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. By default, nothing changes. However, if a specific module is blacklisted (its canonical name), it won't be modprobe'd when requested under its alias (i.e. kernel auto-loading). It would appear as if the given module was unknown. The module can still be loaded under its canonical name, which is an explicit (privileged) user action. Signed-off-by: Michal Koutný Acked-by: Jamal Hadi Salim Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20240201130943.19536-4-mkoutny@suse.com Signed-off-by: Jakub Kicinski

net/sched: simplify tc_action_load_ops parameters

2024-01-07T14:58:26Z

Instead of using two bools derived from a flags passed as arguments to the parent function of tc_action_load_ops, just pass the flags itself to tc_action_load_ops to simplify its parameters. Reviewed-by: Jiri Pirko Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net/sched: introduce ACT_P_BOUND return code

2024-01-04T02:36:24Z

Bound actions always return '0' and as of today we rely on '0' being returned in order to properly skip bound actions in tcf_idr_insert_many. In order to further improve maintainability, introduce the ACT_P_BOUND return code. Actions are updated to return 'ACT_P_BOUND' instead of plain '0'. tcf_idr_insert_many is then updated to check for 'ACT_P_BOUND'. Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20231229132642.1489088-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net: sched: Add initial TC error skb drop reasons

2023-12-20T11:50:13Z

Continue expanding Daniel's patch by adding new skb drop reasons that are idiosyncratic to TC. More specifically: - SKB_DROP_REASON_TC_COOKIE_ERROR: An error occurred whilst processing a tc ext cookie. - SKB_DROP_REASON_TC_CHAIN_NOTFOUND: tc chain lookup failed. - SKB_DROP_REASON_TC_RECLASSIFY_LOOP: tc exceeded max reclassify loop iterations Signed-off-by: Victor Nogueira Reviewed-by: Simon Horman Signed-off-by: David S. Miller

net: sched: Move drop_reason to struct tc_skb_cb

2023-12-20T11:50:13Z

Move drop_reason from struct tcf_result to skb cb - more specifically to struct tc_skb_cb. With that, we'll be able to also set the drop reason for the remaining qdiscs (aside from clsact) that do not have access to tcf_result when time comes to set the skb drop reason. Signed-off-by: Victor Nogueira Acked-by: Daniel Borkmann Reviewed-by: Simon Horman Signed-off-by: David S. Miller

net/sched: act_api: skip idr replace on bound actions

2023-12-14T01:53:59Z

tcf_idr_insert_many will replace the allocated -EBUSY pointer in tcf_idr_check_alloc with the real action pointer, exposing it to all operations. This operation is only needed when the action pointer is created (ACT_P_CREATED). For actions which are bound to (returned 0), the pointer already resides in the idr making such operation a nop. Even though it's a nop, it's still not a cheap operation as internally the idr code walks the idr and then does a replace on the appropriate slot. So if the action was bound, better skip the idr replace entirely. Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Link: https://lore.kernel.org/r/20231211181807.96028-3-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: act_api: rely on rcu in tcf_idr_check_alloc

2023-12-14T01:53:59Z

Instead of relying only on the idrinfo->lock mutex for bind/alloc logic, rely on a combination of rcu + mutex + atomics to better scale the case where multiple rtnl-less filters are binding to the same action object. Action binding happens when an action index is specified explicitly and an action exists which such index exists. Example: tc actions add action drop index 1 tc filter add ... matchall action drop index 1 tc filter add ... matchall action drop index 1 tc filter add ... matchall action drop index 1 tc filter ls ... filter protocol all pref 49150 matchall chain 0 filter protocol all pref 49150 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 filter protocol all pref 49151 matchall chain 0 filter protocol all pref 49151 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 filter protocol all pref 49152 matchall chain 0 filter protocol all pref 49152 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 When no index is specified, as before, grab the mutex and allocate in the idr the next available id. In this version, as opposed to before, it's simplified to store the -EBUSY pointer instead of the previous alloc + replace combination. When an index is specified, rely on rcu to find if there's an object in such index. If there's none, fallback to the above, serializing on the mutex and reserving the specified id. If there's one, it can be an -EBUSY pointer, in which case we just try again until it's an action, or an action. Given the rcu guarantees, the action found could be dead and therefore we need to bump the refcount if it's not 0, handling the case it's in fact 0. As bind and the action refcount are already atomics, these increments can happen without the mutex protection while many tcf_idr_check_alloc race to bind to the same action instance. In case binding encounters a parallel delete or add, it will return -EAGAIN in order to try again. Both filter and action apis already have the retry machinery in-place. In case it's an unlocked filter it retries under the rtnl lock. Signed-off-by: Pedro Tammela Acked-by: Jamal Hadi Salim Reviewed-by: Vlad Buslov Link: https://lore.kernel.org/r/20231211181807.96028-2-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: act_api: conditional notification of events

2023-12-12T02:52:57Z

As of today tc-action events are unconditionally built and sent to RTNLGRP_TC. As with the introduction of rtnl_notify_needed we can check before-hand if they are really needed. Signed-off-by: Pedro Tammela Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231208192847.714940-6-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: act_api: don't open code max()

2023-12-12T02:52:57Z

Use max() in a couple of places that are open coding it with the ternary operator. Signed-off-by: Pedro Tammela Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231208192847.714940-5-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski