IP defrag does not works for UDP VLAN traffic

[ates]

Hello,

I've tried to send UDP data which size is more than MTU via VLAN interface and found what IP defragmentation does not works in this case.

Tested on:

• PF_RING 7.8, CentOS 8.3.2011, kernel 4.18.0-240.el8.x86_64
• PF_RING dev:c449372b7f3d6fb4fe2b86c8197814f2e0a14e2c, Ubuntu 20.04, kernel 5.8.0-63-generic

options passed to pf_ring.ko: enable_debug=2 enable_ip_defrag=1

[687783.079029] [PF_RING] Welcome to PF_RING 8.1.0 ($Revision: dev:c449372b7f3d6fb4fe2b86c8197814f2e0a14e2c$)
                (C) 2004-20 ntop.org
[687783.079031] LINUX_VERSION_CODE 00050812
[687783.079031] [PF_RING] Min # ring slots 4096
[687783.079032] [PF_RING] Slot version     18
[687783.079032] [PF_RING] Capture TX       Yes [RX+TX]
[687783.079032] [PF_RING] IP Defragment    Yes
[687783.079039] NET: Registered protocol family 27

Logs:

[687863.363816] [PF_RING][DEBUG] ring_create:4515 [pid=805720]
[687863.363820] [PF_RING][DEBUG] ring_insert:2025 ring_insert
[687863.363821] [PF_RING][DEBUG] lockless_list_add:638 BEGIN [total=0]
[687863.363822] [PF_RING][DEBUG] lockless_list_add:664 END [total=1][id=0][top_element_id=0]
[687863.363823] [PF_RING][DEBUG] lockless_list_add:669 [slot 0 is full]
[687863.363827] [PF_RING][DEBUG] ring_proc_add:1196 Added /proc/net/pf_ring/805720-none.1
[687863.363827] [PF_RING][DEBUG] ring_create:4589 created
[687863.363832] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=107)
[687863.363834] [PF_RING][DEBUG] ring_setsockopt:7320 --> SO_RING_BUCKET_LEN=65535
[687863.363835] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=127)
[687863.363847] [PF_RING][DEBUG] ring_bind:5611 ring_bind() called
[687863.363848] [PF_RING][DEBUG] ring_bind:5628 searching device wlp3s0
[687863.363850] [PF_RING][DEBUG] packet_ring_bind:5568 packet_ring_bind(wlp3s0, bucket_len=65535) called
[687863.363851] [PF_RING][DEBUG] ring_proc_remove:1215 Removing /proc/net/pf_ring/805720-none.1
[687863.363852] [PF_RING][DEBUG] ring_proc_remove:1219 Removed /proc/net/pf_ring/805720-none.1
[687863.363854] [PF_RING][DEBUG] ring_proc_add:1196 Added /proc/net/pf_ring/805720-wlp3s0.1
[687863.363855] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=108)
[687863.363856] [PF_RING][DEBUG] ring_setsockopt:7005 Setting channel 0
[687863.363857] [PF_RING][DEBUG] ring_setsockopt:7019 [channel_id_mask=FFFFFFFFFFFFFFFF]
[687863.363858] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=141)
[687863.383754] [PF_RING][DEBUG] ring_mmap:5688 called
[687863.383756] [PF_RING][DEBUG] ring_mmap:5696 called, size: 4096 bytes [bucket_len=65535]
[687863.383757] [PF_RING][DEBUG] ring_alloc_mem:1927 ring_alloc_mem(bucket_len=65535)
[687863.383758] [PF_RING][DEBUG] ring_alloc_mem:1970 [PF_RING] Warning: jumbo mtu or snaplen (65535), resizing slots.. (num_slots = 512 x slot_len = 65592)
[687863.388479] [PF_RING][DEBUG] ring_alloc_mem:1985 successfully allocated 33595392 bytes at 0xffffba434de69000
[687863.388481] [PF_RING][DEBUG] ring_alloc_mem:2002 allocated 512 slots [slot_len=65592][tot_mem=33595392]
[687863.388482] [PF_RING][DEBUG] ring_mmap:5747 mmap [slot_len=65592][tot_slots=512] for ring on device wlp3s0
[687863.388484] [PF_RING][DEBUG] do_memory_mmap:5645 mode=0, size=4096, ptr=00000000e571badb
[687863.388489] [PF_RING][DEBUG] ring_mmap:5812 succeeded
[687863.388511] [PF_RING][DEBUG] ring_mmap:5688 called
[687863.388512] [PF_RING][DEBUG] ring_mmap:5696 called, size: 33595392 bytes [bucket_len=65535]
[687863.388513] [PF_RING][DEBUG] ring_mmap:5747 mmap [slot_len=65592][tot_slots=512] for ring on device wlp3s0
[687863.388513] [PF_RING][DEBUG] do_memory_mmap:5645 mode=0, size=33595392, ptr=00000000e571badb
[687863.389182] [PF_RING][DEBUG] ring_mmap:5812 succeeded
[687863.389188] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=140)
[687863.389190] [PF_RING][DEBUG] is_netdev_promisc:5210 checking promisc for wlp3s0
[687863.389192] [PF_RING][DEBUG] set_netdev_promisc:5224 setting promisc for wlp3s0
[687863.389201] device wlp3s0 entered promiscuous mode
[687863.389374] [PF_RING][DEBUG] ring_getsockopt:7632 --> getsockopt(179)
[687863.389376] [PF_RING][DEBUG] ring_getsockopt:7632 --> getsockopt(182)
[687863.389381] [PF_RING][DEBUG] ring_getsockopt:7632 --> getsockopt(184)
[687863.389386] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=117)
[687863.389387] [PF_RING][DEBUG] ring_setsockopt:7299 --> SO_SET_POLL_WATERMARK=1
[687863.390435] [PF_RING][DEBUG] ring_getsockopt:7632 --> getsockopt(184)
[687863.390439] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=26)
[687863.390440] [PF_RING][DEBUG] ring_setsockopt:6897 BPF filter
[687863.390441] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=26)
[687863.390442] [PF_RING][DEBUG] ring_setsockopt:6897 BPF filter
[687863.390475] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=106)
[687863.390476] [PF_RING][DEBUG] ring_setsockopt:7237 * SO_ACTIVATE_RING *
[687900.256909] [PF_RING][DEBUG] add_skb_to_ring:3814 ring_id=1 pfr->filtering_sample_rate=0 pfr->filtering_sampling_size=0
[687900.256946] [PF_RING][DEBUG] add_skb_to_ring:3814 ring_id=1 pfr->filtering_sample_rate=0 pfr->filtering_sampling_size=0
[687903.952629] [PF_RING][DEBUG] ring_setsockopt:6891 --> ring_setsockopt(optname=124)
[687903.953426] [PF_RING][DEBUG] ring_release:5362 called ring_release(wlp3s0)
[687903.953428] [PF_RING][DEBUG] ring_proc_remove:1215 Removing /proc/net/pf_ring/805720-wlp3s0.1
[687903.953430] [PF_RING][DEBUG] ring_proc_remove:1219 Removed /proc/net/pf_ring/805720-wlp3s0.1
[687903.953433] [PF_RING][DEBUG] ring_remove:2058 ring_remove()
[687903.953434] [PF_RING][DEBUG] ring_remove:2072 Found socket to remove
[687903.953435] [PF_RING][DEBUG] lockless_list_remove:692 BEGIN [total=1]
[687903.953436] [PF_RING][DEBUG] lockless_list_remove:711 END [total=0][top_element_id=0]
[687903.953437] [PF_RING][DEBUG] ring_remove:2091 leaving ring_remove()
[687903.954067] [PF_RING][DEBUG] unset_netdev_promisc:5247 resetting promisc for wlp3s0
[687903.954073] device wlp3s0 left promiscuous mode
[687904.059835] [PF_RING][DEBUG] ring_release:5513 ring_release: done

How to reproduce:

Interface with VLAN configured on machine 1:

enp0s3.1@enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 08:00:27:db:5d:1f brd ff:ff:ff:ff:ff:ff
    inet 10.4.0.2/8 brd 10.255.255.255 scope global enp0s3.1
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fedb:5d1f/64 scope link 
       valid_lft forever preferred_lft forever

Interface with VLAN configured on machine 2:

wlp3s0.1@wlp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 5c:e0:c5:a5:da:66 brd ff:ff:ff:ff:ff:ff
    inet 10.4.0.1/8 brd 10.255.255.255 scope global wlp3s0.1
       valid_lft forever preferred_lft forever
    inet6 fe80::5ee0:c5ff:fea5:da66/64 scope link 
       valid_lft forever preferred_lft forever

Send data from machine 1 to machine 2:

cat /etc/sysctl.conf | nc -u 10.4.0.1 50000

Run tcpdump on machine 2:

tcpdump -i wlp3s0.1 -e -n -vvv
tcpdump: listening on wlp3s0.1, link-type EN10MB (Ethernet), capture size 262144 bytes
15:24:45.441002 08:00:27:db:5d:1f > 5c:e0:c5:a5:da:66, ethertype 802.1Q (0x8100), length 1518: vlan 1, p 0, ethertype IPv4, (tos 0x0, ttl 64, id 32461, offset 0, flags [+], proto UDP (17), length 1500)
    10.4.0.2.41556 > 10.4.0.1.50000: UDP, bad length 2683 > 1472
15:24:45.441036 08:00:27:db:5d:1f > 5c:e0:c5:a5:da:66, ethertype 802.1Q (0x8100), length 1249: vlan 1, p 0, ethertype IPv4, (tos 0x0, ttl 64, id 32461, offset 1480, flags [none], proto UDP (17), length 1231)
    10.4.0.2 > 10.4.0.1: ip-proto-17

Also tested on interfaces without VLAN configured and it's works (sent the same data using nc):

tcpdump -i wlp3s0 -e -n -vvv "udp port 50000"
tcpdump: listening on wlp3s0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:27:18.141203 08:00:27:db:5d:1f > 5c:e0:c5:a5:da:66, ethertype IPv4 (0x0800), length 2725: (tos 0x0, ttl 64, id 22009, offset 0, flags [none], proto UDP (17), length 2711)
    10.10.1.41.54100 > 10.10.1.111.50000: [udp sum ok] UDP, length 2683

Here is pcaps for both cases: pf_ring_defrag_vlan.zip

[ates]

VLAN stripping offload is disabled

rx-vlan-offload: off
tx-vlan-offload: off [requested on]
rx-vlan-filter: on [fixed]