linux.git/net/core/drop_monitor.c, branch v5.19

net: dm: check the boundary of skb drop reasons

2022-05-16T09:47:43+00:00

The 'reason' will be set to 'SKB_DROP_REASON_NOT_SPECIFIED' if it not
small that SKB_DROP_REASON_MAX in net_dm_packet_trace_kfree_skb_hit(),
but it can't avoid it to be 0, which is invalid and can cause NULL
pointer in drop_reasons.

Therefore, reset it to SKB_DROP_REASON_NOT_SPECIFIED when 'reason <= 0'.

Reviewed-by: Jiang Biao 
Reviewed-by: Hao Peng 
Signed-off-by: Menglong Dong 
Signed-off-by: David S. Miller

drop_monitor: remove quadratic behavior

2022-02-23T12:39:58+00:00

drop_monitor is using an unique list on which all netdevices in
the host have an element, regardless of their netns.

This scales poorly, not only at device unregister time (what I
caught during my netns dismantle stress tests), but also at packet
processing time whenever trace_napi_poll_hit() is called.

If the intent was to avoid adding one pointer in 'struct net_device'
then surely we prefer O(1) behavior.

Signed-off-by: Eric Dumazet 
Cc: Neil Horman 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2022-02-17T19:44:20+00:00

No conflicts.

Signed-off-by: Jakub Kicinski

drop_monitor: fix data-race in dropmon_net_event / trace_napi_poll_hit

2022-02-11T11:20:32+00:00

trace_napi_poll_hit() is reading stat->dev while another thread can write
on it from dropmon_net_event()

Use READ_ONCE()/WRITE_ONCE() here, RCU rules are properly enforced already,
we only have to take care of load/store tearing.

BUG: KCSAN: data-race in dropmon_net_event / trace_napi_poll_hit

write to 0xffff88816f3ab9c0 of 8 bytes by task 20260 on cpu 1:
 dropmon_net_event+0xb8/0x2b0 net/core/drop_monitor.c:1579
 notifier_call_chain kernel/notifier.c:84 [inline]
 raw_notifier_call_chain+0x53/0xb0 kernel/notifier.c:392
 call_netdevice_notifiers_info net/core/dev.c:1919 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1931 [inline]
 call_netdevice_notifiers net/core/dev.c:1945 [inline]
 unregister_netdevice_many+0x867/0xfb0 net/core/dev.c:10415
 ip_tunnel_delete_nets+0x24a/0x280 net/ipv4/ip_tunnel.c:1123
 vti_exit_batch_net+0x2a/0x30 net/ipv4/ip_vti.c:515
 ops_exit_list net/core/net_namespace.c:173 [inline]
 cleanup_net+0x4dc/0x8d0 net/core/net_namespace.c:597
 process_one_work+0x3f6/0x960 kernel/workqueue.c:2307
 worker_thread+0x616/0xa70 kernel/workqueue.c:2454
 kthread+0x1bf/0x1e0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

read to 0xffff88816f3ab9c0 of 8 bytes by interrupt on cpu 0:
 trace_napi_poll_hit+0x89/0x1c0 net/core/drop_monitor.c:292
 trace_napi_poll include/trace/events/napi.h:14 [inline]
 __napi_poll+0x36b/0x3f0 net/core/dev.c:6366
 napi_poll net/core/dev.c:6432 [inline]
 net_rx_action+0x29e/0x650 net/core/dev.c:6519
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 do_softirq+0xb1/0xf0 kernel/softirq.c:459
 __local_bh_enable_ip+0x68/0x70 kernel/softirq.c:383
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline]
 _raw_spin_unlock_bh+0x33/0x40 kernel/locking/spinlock.c:210
 spin_unlock_bh include/linux/spinlock.h:394 [inline]
 ptr_ring_consume_bh include/linux/ptr_ring.h:367 [inline]
 wg_packet_decrypt_worker+0x73c/0x780 drivers/net/wireguard/receive.c:506
 process_one_work+0x3f6/0x960 kernel/workqueue.c:2307
 worker_thread+0x616/0xa70 kernel/workqueue.c:2454
 kthread+0x1bf/0x1e0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

value changed: 0xffff88815883e000 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26435 Comm: kworker/0:1 Not tainted 5.17.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: wg-crypt-wg2 wg_packet_decrypt_worker

Fixes: 4ea7e38696c7 ("dropmon: add ability to detect when hardware dropsrxpackets")
Signed-off-by: Eric Dumazet 
Cc: Neil Horman 
Reported-by: syzbot 
Signed-off-by: David S. Miller

net: drop_monitor: support drop reason

2022-02-10T01:25:57+00:00

In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()")
drop reason is introduced to the tracepoint of kfree_skb. Therefore,
drop_monitor is able to report the drop reason to users by netlink.

The drop reasons are reported as string to users, which is exactly
the same as what we do when reporting it to ftrace.

Signed-off-by: Menglong Dong 
Reviewed-by: Ido Schimmel 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20220209060838.55513-1-imagedong@tencent.com
Signed-off-by: Jakub Kicinski

net: skb: introduce kfree_skb_reason()

2022-01-10T00:30:34+00:00

Introduce the interface kfree_skb_reason(), which is able to pass
the reason why the skb is dropped to 'kfree_skb' tracepoint.

Add the 'reason' field to 'trace_kfree_skb', therefor user can get
more detail information about abnormal skb with 'drop_monitor' or
eBPF.

All drop reasons are defined in the enum 'skb_drop_reason', and
they will be print as string in 'kfree_skb' tracepoint in format
of 'reason: XXX'.

( Maybe the reasons should be defined in a uapi header file, so that
user space can use them? )

Signed-off-by: Menglong Dong 
Signed-off-by: Jakub Kicinski

drop_monitor: add net device refcount tracker

2021-12-07T00:05:10+00:00

We want to track all dev_hold()/dev_put() to ease leak hunting.

Signed-off-by: Eric Dumazet 
Signed-off-by: Jakub Kicinski

net: Remove redundant if statements

2021-08-05T12:27:50+00:00

The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.

Signed-off-by: Yajun Deng 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2021-03-25T22:31:22+00:00

Signed-off-by: David S. Miller

/net/core/: fix misspellings using codespell tool

2021-03-19T02:13:41+00:00

A typo is found out by codespell tool in 1734th line of drop_monitor.c:

$ codespell ./net/core/
./net/core/drop_monitor.c:1734: guarnateed  ==> guaranteed

Fix a typo found by codespell.

Signed-off-by: Xiong Zhenwu 
Signed-off-by: David S. Miller