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* net: bridge: mst: fix vlan use-after-freeNikolay Aleksandrov2024-05-151-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | syzbot reported a suspicious rcu usage[1] in bridge's mst code. While fixing it I noticed that nothing prevents a vlan to be freed while walking the list from the same path (br forward delay timer). Fix the rcu usage and also make sure we are not accessing freed memory by making br_mst_vlan_set_state use rcu read lock. [1] WARNING: suspicious RCU usage 6.9.0-rc6-syzkaller #0 Not tainted ----------------------------- net/bridge/br_private.h:1599 suspicious rcu_dereference_protected() usage! ... stack backtrace: CPU: 1 PID: 8017 Comm: syz-executor.1 Not tainted 6.9.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 lockdep_rcu_suspicious+0x221/0x340 kernel/locking/lockdep.c:6712 nbp_vlan_group net/bridge/br_private.h:1599 [inline] br_mst_set_state+0x1ea/0x650 net/bridge/br_mst.c:105 br_set_state+0x28a/0x7b0 net/bridge/br_stp.c:47 br_forward_delay_timer_expired+0x176/0x440 net/bridge/br_stp_timer.c:88 call_timer_fn+0x18e/0x650 kernel/time/timer.c:1793 expire_timers kernel/time/timer.c:1844 [inline] __run_timers kernel/time/timer.c:2418 [inline] __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2429 run_timer_base kernel/time/timer.c:2438 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2448 __do_softirq+0x2c6/0x980 kernel/softirq.c:554 invoke_softirq kernel/softirq.c:428 [inline] __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633 irq_exit_rcu+0x9/0x30 kernel/softirq.c:645 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5758 Code: 2b 00 74 08 4c 89 f7 e8 ba d1 84 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25 RSP: 0018:ffffc90013657100 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 1ffff920026cae2c RCX: 0000000000000001 RDX: dffffc0000000000 RSI: ffffffff8bcaca00 RDI: ffffffff8c1eaa60 RBP: ffffc90013657260 R08: ffffffff92efe507 R09: 1ffffffff25dfca0 R10: dffffc0000000000 R11: fffffbfff25dfca1 R12: 1ffff920026cae28 R13: dffffc0000000000 R14: ffffc90013657160 R15: 0000000000000246 Fixes: ec7328b59176 ("net: bridge: mst: Multiple Spanning Tree (MST) mode") Reported-by: syzbot+fa04eb8a56fd923fc5d8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fa04eb8a56fd923fc5d8 Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: bridge: mst: Add helper to query a port's MST stateTobias Waldekranz2022-03-181-0/+25
| | | | | | | | | | | | This is useful for switchdev drivers who are offloading MST states into hardware. As an example, a driver may wish to flush the FDB for a port when it transitions from forwarding to blocking - which means that the previous state must be discoverable. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Add helper to check if MST is enabledTobias Waldekranz2022-03-181-0/+9
| | | | | | | | | | This is useful for switchdev drivers that might want to refuse to join a bridge where MST is enabled, if the hardware can't support it. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Add helper to map an MSTI to a VID setTobias Waldekranz2022-03-181-0/+26
| | | | | | | | | | | | | | | | | | br_mst_get_info answers the question: "On this bridge, which VIDs are mapped to the given MSTI?" This is useful in switchdev drivers, which might have to fan-out operations, relating to an MSTI, per VLAN. An example: When a port's MST state changes from forwarding to blocking, a driver may choose to flush the dynamic FDB entries on that port to get faster reconvergence of the network, but this should only be done in the VLANs that are managed by the MSTI in question. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Reviewed-by: Vladimir Oltean <olteanv@gmail.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Notify switchdev drivers of MST state changesTobias Waldekranz2022-03-181-0/+18
| | | | | | | | | | Generate a switchdev notification whenever an MST state changes. This notification is keyed by the VLANs MSTI rather than the VID, since multiple VLANs may share the same MST instance. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Notify switchdev drivers of VLAN MSTI migrationsTobias Waldekranz2022-03-181-0/+13
| | | | | | | | | Whenever a VLAN moves to a new MSTI, send a switchdev notification so that switchdevs can track a bridge's VID to MSTI mappings. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Notify switchdev drivers of MST mode changesTobias Waldekranz2022-03-181-0/+11
| | | | | | | | | | Trigger a switchdev event whenever the bridge's MST mode is enabled/disabled. This allows constituent ports to either perform any required hardware config, or refuse the change if it not supported. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Support setting and reporting MST port statesTobias Waldekranz2022-03-181-0/+126
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make it possible to change the port state in a given MSTI by extending the bridge port netlink interface (RTM_SETLINK on PF_BRIDGE).The proposed iproute2 interface would be: bridge mst set dev <PORT> msti <MSTI> state <STATE> Current states in all applicable MSTIs can also be dumped via a corresponding RTM_GETLINK. The proposed iproute interface looks like this: $ bridge mst port msti vb1 0 state forwarding 100 state disabled vb2 0 state forwarding 100 state forwarding The preexisting per-VLAN states are still valid in the MST mode (although they are read-only), and can be queried as usual if one is interested in knowing a particular VLAN's state without having to care about the VID to MSTI mapping (in this example VLAN 20 and 30 are bound to MSTI 100): $ bridge -d vlan port vlan-id vb1 10 state forwarding mcast_router 1 20 state disabled mcast_router 1 30 state disabled mcast_router 1 40 state forwarding mcast_router 1 vb2 10 state forwarding mcast_router 1 20 state forwarding mcast_router 1 30 state forwarding mcast_router 1 40 state forwarding mcast_router 1 Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Allow changing a VLAN's MSTITobias Waldekranz2022-03-181-0/+42
| | | | | | | | | | | | | | | | Allow a VLAN to move out of the CST (MSTI 0), to an independent tree. The user manages the VID to MSTI mappings via a global VLAN setting. The proposed iproute2 interface would be: bridge vlan global set dev br0 vid <VID> msti <MSTI> Changing the state in non-zero MSTIs is still not supported, but will be addressed in upcoming changes. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
* net: bridge: mst: Multiple Spanning Tree (MST) modeTobias Waldekranz2022-03-181-0/+87
Allow the user to switch from the current per-VLAN STP mode to an MST mode. Up to this point, per-VLAN STP states where always isolated from each other. This is in contrast to the MSTP standard (802.1Q-2018, Clause 13.5), where VLANs are grouped into MST instances (MSTIs), and the state is managed on a per-MSTI level, rather that at the per-VLAN level. Perhaps due to the prevalence of the standard, many switching ASICs are built after the same model. Therefore, add a corresponding MST mode to the bridge, which we can later add offloading support for in a straight-forward way. For now, all VLANs are fixed to MSTI 0, also called the Common Spanning Tree (CST). That is, all VLANs will follow the port-global state. Upcoming changes will make this actually useful by allowing VLANs to be mapped to arbitrary MSTIs and allow individual MSTI states to be changed. Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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