From 0a13c1e0a449917b29c45d90701eededa69c99d3 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 7 Mar 2025 20:47:26 -0800 Subject: net: revert to lockless TC_SETUP_BLOCK and TC_SETUP_FT There is a couple of places from which we can arrive to ndo_setup_tc with TC_SETUP_BLOCK/TC_SETUP_FT: - netlink - netlink notifier - netdev notifier Locking netdev too deep in this call chain seems to be problematic (especially assuming some/all of the call_netdevice_notifiers NETDEV_UNREGISTER) might soon be running with the instance lock). Revert to lockless ndo_setup_tc for TC_SETUP_BLOCK/TC_SETUP_FT. NFT framework already takes care of most of the locking. Document the assumptions. ndo_setup_tc TC_SETUP_BLOCK nft_block_offload_cmd nft_chain_offload_cmd nft_flow_block_chain nft_flow_offload_chain nft_flow_rule_offload_abort nft_flow_rule_offload_commit nft_flow_rule_offload_commit nf_tables_commit nfnetlink_rcv_batch nfnetlink_rcv_skb_batch nfnetlink_rcv nft_offload_netdev_event NETDEV_UNREGISTER notifier ndo_setup_tc TC_SETUP_FT nf_flow_table_offload_cmd nf_flow_table_offload_setup nft_unregister_flowtable_hook nft_register_flowtable_net_hooks nft_flowtable_update nf_tables_newflowtable nfnetlink_rcv_batch (.call NFNL_CB_BATCH) nft_flowtable_update nf_tables_newflowtable nft_flowtable_event nf_tables_flowtable_event NETDEV_UNREGISTER notifier __nft_unregister_flowtable_net_hooks nft_unregister_flowtable_net_hooks nf_tables_commit nfnetlink_rcv_batch (.call NFNL_CB_BATCH) __nf_tables_abort nf_tables_abort nfnetlink_rcv_batch __nft_release_hook __nft_release_hooks nf_tables_pre_exit_net -> module unload nft_rcv_nl_event netlink_register_notifier (oh boy) nft_register_flowtable_net_hooks nft_flowtable_update nf_tables_newflowtable nf_tables_newflowtable Fixes: c4f0f30b424e ("net: hold netdev instance lock during nft ndo_setup_tc") Signed-off-by: Stanislav Fomichev Reported-by: syzbot+0afb4bcf91e5a1afdcad@syzkaller.appspotmail.com Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250308044726.1193222-1-sdf@fomichev.me Signed-off-by: Jakub Kicinski --- include/linux/netdevice.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/netdevice.h') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 9a297757df7e..0dbfe069a6e3 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3316,8 +3316,6 @@ int dev_open(struct net_device *dev, struct netlink_ext_ack *extack); void netif_close(struct net_device *dev); void dev_close(struct net_device *dev); void dev_close_many(struct list_head *head, bool unlink); -int dev_setup_tc(struct net_device *dev, enum tc_setup_type type, - void *type_data); void netif_disable_lro(struct net_device *dev); void dev_disable_lro(struct net_device *dev); int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *newskb); -- cgit v1.2.3