linux/net/core/dev_addr_lists.c, branch v5.10

net: core: add nested_level variable in net_device

2020-09-28T22:00:15Z

This patch is to add a new variable 'nested_level' into the net_device structure. This variable will be used as a parameter of spin_lock_nested() of dev->addr_list_lock. netif_addr_lock() can be called recursively so spin_lock_nested() is used instead of spin_lock() and dev->lower_level is used as a parameter of spin_lock_nested(). But, dev->lower_level value can be updated while it is being used. So, lockdep would warn a possible deadlock scenario. When a stacked interface is deleted, netif_{uc | mc}_sync() is called recursively. So, spin_lock_nested() is called recursively too. At this moment, the dev->lower_level variable is used as a parameter of it. dev->lower_level value is updated when interfaces are being unlinked/linked immediately. Thus, After unlinking, dev->lower_level shouldn't be a parameter of spin_lock_nested(). A (macvlan) | B (vlan) | C (bridge) | D (macvlan) | E (vlan) | F (bridge) A->lower_level : 6 B->lower_level : 5 C->lower_level : 4 D->lower_level : 3 E->lower_level : 2 F->lower_level : 1 When an interface 'A' is removed, it releases resources. At this moment, netif_addr_lock() would be called. Then, netdev_upper_dev_unlink() is called recursively. Then dev->lower_level is updated. There is no problem. But, when the bridge module is removed, 'C' and 'F' interfaces are removed at once. If 'F' is removed first, a lower_level value is like below. A->lower_level : 5 B->lower_level : 4 C->lower_level : 3 D->lower_level : 2 E->lower_level : 1 F->lower_level : 1 Then, 'C' is removed. at this moment, netif_addr_lock() is called recursively. The ordering is like this. C(3)->D(2)->E(1)->F(1) At this moment, the lower_level value of 'E' and 'F' are the same. So, lockdep warns a possible deadlock scenario. In order to avoid this problem, a new variable 'nested_level' is added. This value is the same as dev->lower_level - 1. But this value is updated in rtnl_unlock(). So, this variable can be used as a parameter of spin_lock_nested() safely in the rtnl context. Test commands: ip link add br0 type bridge vlan_filtering 1 ip link add vlan1 link br0 type vlan id 10 ip link add macvlan2 link vlan1 type macvlan ip link add br3 type bridge vlan_filtering 1 ip link set macvlan2 master br3 ip link add vlan4 link br3 type vlan id 10 ip link add macvlan5 link vlan4 type macvlan ip link add br6 type bridge vlan_filtering 1 ip link set macvlan5 master br6 ip link add vlan7 link br6 type vlan id 10 ip link add macvlan8 link vlan7 type macvlan ip link set br0 up ip link set vlan1 up ip link set macvlan2 up ip link set br3 up ip link set vlan4 up ip link set macvlan5 up ip link set br6 up ip link set vlan7 up ip link set macvlan8 up modprobe -rv bridge Splat looks like: [ 36.057436][ T744] WARNING: possible recursive locking detected [ 36.058848][ T744] 5.9.0-rc6+ #728 Not tainted [ 36.059959][ T744] -------------------------------------------- [ 36.061391][ T744] ip/744 is trying to acquire lock: [ 36.062590][ T744] ffff8c4767509280 (&vlan_netdev_addr_lock_key){+...}-{2:2}, at: dev_set_rx_mode+0x19/0x30 [ 36.064922][ T744] [ 36.064922][ T744] but task is already holding lock: [ 36.066626][ T744] ffff8c4767769280 (&vlan_netdev_addr_lock_key){+...}-{2:2}, at: dev_uc_add+0x1e/0x60 [ 36.068851][ T744] [ 36.068851][ T744] other info that might help us debug this: [ 36.070731][ T744] Possible unsafe locking scenario: [ 36.070731][ T744] [ 36.072497][ T744] CPU0 [ 36.073238][ T744] ---- [ 36.074007][ T744] lock(&vlan_netdev_addr_lock_key); [ 36.075290][ T744] lock(&vlan_netdev_addr_lock_key); [ 36.076590][ T744] [ 36.076590][ T744] *** DEADLOCK *** [ 36.076590][ T744] [ 36.078515][ T744] May be due to missing lock nesting notation [ 36.078515][ T744] [ 36.080491][ T744] 3 locks held by ip/744: [ 36.081471][ T744] #0: ffffffff98571df0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x236/0x490 [ 36.083614][ T744] #1: ffff8c4767769280 (&vlan_netdev_addr_lock_key){+...}-{2:2}, at: dev_uc_add+0x1e/0x60 [ 36.085942][ T744] #2: ffff8c476c8da280 (&bridge_netdev_addr_lock_key/4){+...}-{2:2}, at: dev_uc_sync+0x39/0x80 [ 36.088400][ T744] [ 36.088400][ T744] stack backtrace: [ 36.089772][ T744] CPU: 6 PID: 744 Comm: ip Not tainted 5.9.0-rc6+ #728 [ 36.091364][ T744] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 36.093630][ T744] Call Trace: [ 36.094416][ T744] dump_stack+0x77/0x9b [ 36.095385][ T744] __lock_acquire+0xbc3/0x1f40 [ 36.096522][ T744] lock_acquire+0xb4/0x3b0 [ 36.097540][ T744] ? dev_set_rx_mode+0x19/0x30 [ 36.098657][ T744] ? rtmsg_ifinfo+0x1f/0x30 [ 36.099711][ T744] ? __dev_notify_flags+0xa5/0xf0 [ 36.100874][ T744] ? rtnl_is_locked+0x11/0x20 [ 36.101967][ T744] ? __dev_set_promiscuity+0x7b/0x1a0 [ 36.103230][ T744] _raw_spin_lock_bh+0x38/0x70 [ 36.104348][ T744] ? dev_set_rx_mode+0x19/0x30 [ 36.105461][ T744] dev_set_rx_mode+0x19/0x30 [ 36.106532][ T744] dev_set_promiscuity+0x36/0x50 [ 36.107692][ T744] __dev_set_promiscuity+0x123/0x1a0 [ 36.108929][ T744] dev_set_promiscuity+0x1e/0x50 [ 36.110093][ T744] br_port_set_promisc+0x1f/0x40 [bridge] [ 36.111415][ T744] br_manage_promisc+0x8b/0xe0 [bridge] [ 36.112728][ T744] __dev_set_promiscuity+0x123/0x1a0 [ 36.113967][ T744] ? __hw_addr_sync_one+0x23/0x50 [ 36.115135][ T744] __dev_set_rx_mode+0x68/0x90 [ 36.116249][ T744] dev_uc_sync+0x70/0x80 [ 36.117244][ T744] dev_uc_add+0x50/0x60 [ 36.118223][ T744] macvlan_open+0x18e/0x1f0 [macvlan] [ 36.119470][ T744] __dev_open+0xd6/0x170 [ 36.120470][ T744] __dev_change_flags+0x181/0x1d0 [ 36.121644][ T744] dev_change_flags+0x23/0x60 [ 36.122741][ T744] do_setlink+0x30a/0x11e0 [ 36.123778][ T744] ? __lock_acquire+0x92c/0x1f40 [ 36.124929][ T744] ? __nla_validate_parse.part.6+0x45/0x8e0 [ 36.126309][ T744] ? __lock_acquire+0x92c/0x1f40 [ 36.127457][ T744] __rtnl_newlink+0x546/0x8e0 [ 36.128560][ T744] ? lock_acquire+0xb4/0x3b0 [ 36.129623][ T744] ? deactivate_slab.isra.85+0x6a1/0x850 [ 36.130946][ T744] ? __lock_acquire+0x92c/0x1f40 [ 36.132102][ T744] ? lock_acquire+0xb4/0x3b0 [ 36.133176][ T744] ? is_bpf_text_address+0x5/0xe0 [ 36.134364][ T744] ? rtnl_newlink+0x2e/0x70 [ 36.135445][ T744] ? rcu_read_lock_sched_held+0x32/0x60 [ 36.136771][ T744] ? kmem_cache_alloc_trace+0x2d8/0x380 [ 36.138070][ T744] ? rtnl_newlink+0x2e/0x70 [ 36.139164][ T744] rtnl_newlink+0x47/0x70 [ ... ] Fixes: 845e0ebb4408 ("net: change addr_list_lock back to static key") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller

net: explain the lockdep annotations for dev_uc_unsync()

2020-06-29T04:38:27Z

The lockdep annotations for dev_uc_unsync() and dev_mc_unsync() are not easy to understand, so add some comments to explain why they are correct. Similar for the rest netif_addr_lock_bh() cases, they don't need nested version. Cc: Taehee Yoo Cc: Dmitry Vyukov Signed-off-by: Cong Wang Signed-off-by: David S. Miller

net: change addr_list_lock back to static key

2020-06-09T19:59:45Z

The dynamic key update for addr_list_lock still causes troubles, for example the following race condition still exists: CPU 0: CPU 1: (RCU read lock) (RTNL lock) dev_mc_seq_show() netdev_update_lockdep_key() -> lockdep_unregister_key() -> netif_addr_lock_bh() because lockdep doesn't provide an API to update it atomically. Therefore, we have to move it back to static keys and use subclass for nest locking like before. In commit 1a33e10e4a95 ("net: partially revert dynamic lockdep key changes"), I already reverted most parts of commit ab92d68fc22f ("net: core: add generic lockdep keys"). This patch reverts the rest and also part of commit f3b0a18bb6cb ("net: remove unnecessary variables and callback"). After this patch, addr_list_lock changes back to using static keys and subclasses to satisfy lockdep. Thanks to dev->lower_level, we do not have to change back to ->ndo_get_lock_subclass(). And hopefully this reduces some syzbot lockdep noises too. Reported-by: syzbot+f3a0e80c34b3fc28ac5e@syzkaller.appspotmail.com Cc: Taehee Yoo Cc: Dmitry Vyukov Signed-off-by: Cong Wang Signed-off-by: David S. Miller

net: remove unnecessary variables and callback

2019-10-24T21:53:49Z

This patch removes variables and callback these are related to the nested device structure. devices that can be nested have their own nest_level variable that represents the depth of nested devices. In the previous patch, new {lower/upper}_level variables are added and they replace old private nest_level variable. So, this patch removes all 'nest_level' variables. In order to avoid lockdep warning, ->ndo_get_lock_subclass() was added to get lockdep subclass value, which is actually lower nested depth value. But now, they use the dynamic lockdep key to avoid lockdep warning instead of the subclass. So, this patch removes ->ndo_get_lock_subclass() callback. Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

net: dev: Issue NETDEV_PRE_CHANGEADDR

2018-12-14T02:41:38Z

When a device address is about to be changed, or an address added to the list of device HW addresses, it is necessary to ensure that all interested parties can support the address. Therefore, send the NETDEV_PRE_CHANGEADDR notification, and if anyone bails on it, do not change the address. Signed-off-by: Petr Machata Acked-by: Jiri Pirko Reviewed-by: Ido Schimmel Signed-off-by: David S. Miller

net: core: dev_addr_lists: add auxiliary func to handle reference address updates

2018-11-09T04:30:57Z

In order to avoid all table update, and only remove or add new address, the auxiliary function exists, named __hw_addr_sync_dev(). It allows end driver do nothing when nothing changed and add/rm when concrete address is firstly added or lastly removed. But it doesn't include cases when an address of real device or vlan was reused by other vlans or vlan/macval devices. For handaling events when address was reused/unreused the patch adds new auxiliary routine - __hw_addr_ref_sync_dev(). It allows to do nothing when nothing was changed and do updates only for an address being added/reused/deleted/unreused. Thus, clone address changes for vlans can be mirrored in the table. The function is exclusive with __hw_addr_sync_dev(). It's responsibility of the end driver to identify address vlan device, if it needs so. Signed-off-by: Ivan Khoronzhuk Signed-off-by: David S. Miller

net: change the comment of dev_mc_init

2018-04-19T16:58:20Z

The comment of dev_mc_init() is wrong. which use dev_mc_flush instead of dev_mc_init. Signed-off-by: Lianwen Sun

net: fix uninit-value in __hw_addr_add_ex()

2018-04-08T02:32:31Z

syzbot complained : BUG: KMSAN: uninit-value in memcmp+0x119/0x180 lib/string.c:861 CPU: 0 PID: 3 Comm: kworker/0:0 Not tainted 4.16.0+ #82 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:53 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 memcmp+0x119/0x180 lib/string.c:861 __hw_addr_add_ex net/core/dev_addr_lists.c:60 [inline] __dev_mc_add+0x1c2/0x8e0 net/core/dev_addr_lists.c:670 dev_mc_add+0x6d/0x80 net/core/dev_addr_lists.c:687 igmp6_group_added+0x2db/0xa00 net/ipv6/mcast.c:662 ipv6_dev_mc_inc+0xe9e/0x1130 net/ipv6/mcast.c:914 addrconf_join_solict net/ipv6/addrconf.c:2078 [inline] addrconf_dad_begin net/ipv6/addrconf.c:3828 [inline] addrconf_dad_work+0x427/0x2150 net/ipv6/addrconf.c:3954 process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2113 worker_thread+0x113c/0x24f0 kernel/workqueue.c:2247 kthread+0x539/0x720 kernel/kthread.c:239 Fixes: f001fde5eadd ("net: introduce a list of device addresses dev_addr_list (v6)") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller

net: fix spelling for synchronized

2014-11-18T20:26:32Z

Signed-off-by: Fabian Frederick Signed-off-by: David S. Miller