[Bug 1747] New: Connection Tracking - TC_DROP in SK_BUFF

bugzilla-daemon at netfilter.org bugzilla-daemon at netfilter.org
Thu Apr 18 00:01:11 CEST 2024


https://bugzilla.netfilter.org/show_bug.cgi?id=1747

            Bug ID: 1747
           Summary: Connection Tracking - TC_DROP in SK_BUFF
           Product: netfilter/iptables
           Version: unspecified
          Hardware: x86_64
                OS: other
            Status: NEW
          Severity: critical
          Priority: P5
         Component: nf_conntrack
          Assignee: netfilter-buglog at lists.netfilter.org
          Reporter: gmckee at crusoeenergy.com

Hi,

We are having issues with Connection Tracking / TC and its interaction with
Open vSwitch.

NAME="Rocky Linux"
VERSION="9.3 (Blue Onyx)"
ID="rocky"
ID_LIKE="rhel centos fedora"
VERSION_ID="9.3"
PLATFORM_ID="platform:el9"
PRETTY_NAME="Rocky Linux 9.3 (Blue Onyx)"
ANSI_COLOR="0;32"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:rocky:rocky:9::baseos"
HOME_URL="https://rockylinux.org/"
BUG_REPORT_URL="https://bugs.rockylinux.org/"
SUPPORT_END="2032-05-31"
ROCKY_SUPPORT_PRODUCT="Rocky-Linux-9"
ROCKY_SUPPORT_PRODUCT_VERSION="9.3"
REDHAT_SUPPORT_PRODUCT="Rocky Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="9.3"

uname -r 
5.14.0-362.8.1.el9_3.x86_64

[root at vaeq-cu2b-r109-prod-hv-03 cloud-user]# modinfo openvswitch
filename:      
/lib/modules/5.14.0-362.8.1.el9_3.x86_64/kernel/net/openvswitch/openvswitch.ko.xz
alias:          net-pf-16-proto-16-family-ovs_ct_limit
alias:          net-pf-16-proto-16-family-ovs_meter
alias:          net-pf-16-proto-16-family-ovs_packet
alias:          net-pf-16-proto-16-family-ovs_flow
alias:          net-pf-16-proto-16-family-ovs_vport
alias:          net-pf-16-proto-16-family-ovs_datapath
license:        GPL
description:    Open vSwitch switching datapath
rhelversion:    9.3
srcversion:     8A2159D727C8BADC82261B8
depends:        nf_conntrack,nf_conncount,libcrc32c,nf_nat
retpoline:      Y
intree:         Y
name:           openvswitch
vermagic:       5.14.0-362.8.1.el9_3.x86_64 SMP preempt mod_unload modversions
sig_id:         PKCS#7
signer:         Rocky kernel signing key
sig_key:        17:CA:DE:1F:EC:D1:59:2D:9F:52:34:C6:7C:09:06:81:3D:74:7C:F7
sig_hashalgo:   sha256
signature:      67:31:56:70:86:DB:57:69:8D:4A:9B:A7:ED:17:F3:67:65:98:97:08:
        1F:FB:4D:F8:A8:2D:7C:A7:7D:3A:57:85:CA:67:9D:82:72:EB:54:14:
        F2:BB:40:78:AD:85:56:2D:EF:D5:00:95:38:A4:86:9F:5F:29:1A:81:
        32:94:B4:87:41:94:A0:3E:71:A5:97:44:2E:42:DD:F7:42:6B:69:94:
        E3:AB:6E:E5:4F:C9:60:57:70:07:5F:CA:C7:83:7A:2F:C7:81:62:FF:
        53:AF:AC:2B:06:D8:08:D3:1D:A7:F0:43:10:98:DE:B1:62:AE:89:A5:
        FE:EF:74:09:0F:2D:0F:D9:73:A5:59:75:D0:87:1E:EA:3A:40:86:1E:
        76:E5:E7:3B:59:2E:3A:7E:65:F3:92:A1:B4:84:48:3F:43:A0:D7:1C:
        21:29:E0:B6:D1:10:36:15:88:43:6A:11:8F:55:EE:1B:F9:53:3B:86:
        EF:81:71:17:81:08:EC:53:30:D6:69:8E:13:11:D5:DF:15:75:88:50:
        69:19:51:3B:41:6B:6F:E0:7A:30:33:32:E6:60:18:02:A6:0C:63:9B:
        C5:D7:2F:6A:D0:BA:45:03:19:0E:21:E8:18:FB:E8:D1:C1:33:05:36:
        1F:9B:0F:29:3F:05:51:7A:30:86:88:B7:C7:44:2E:2B:50:F9:EF:4F:
        D4:70:EA:1B:33:E2:F0:E3:E2:88:00:E5:BF:06:E2:D4:B7:81:EE:6E:
        89:02:18:65:8B:1C:84:42:2F:89:14:63:1D:51:70:37:42:C5:68:DD:
        4D:12:7B:07:33:2B:C6:BC:8F:7F:23:D7:58:DF:47:AC:DE:08:67:FE:
        CB:E8:E6:4D:95:2F:6B:F5:07:4D:32:92:80:0A:7C:D1:B6:81:EE:AB:
        26:C3:C6:22:77:00:5E:64:DE:96:0E:9F:A4:A0:F0:45:9F:19:73:EB:
        CC:60:AE:E9:63:E2:6D:2E:BA:65:9B:BD:04:CC:13:C2:55:88:05:03:
        1B:30:18:8B

I'm not sure where this is failing right now 

Let me explain the issue .

We send a TCP connection to download a file over a TLS connection

What we see is the session gets established , but look at frame 14 , this
traffic is part of the same session , but its not being NATTED (172.27.18.244 -
this is private IP of the VM). Its unclear to me why this would happen.


```
No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
      4 09:23:40.660635    204.52.24.116         104.18.2.35           TCP     
70     57394 → 443 [SYN] Seq=0 Win=42340 Len=0 MSS=1460 SACK_PERM WS=4096
10.014701

Frame 4: 70 bytes on wire (560 bits), 70 bytes captured (560 bits)
Ethernet II, Src: 4e:42:14:a1:2a:fb (4e:42:14:a1:2a:fb), Dst: IETF-VRRP-VRID_ff
(00:00:5e:00:01:ff)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
Internet Protocol Version 4, Src: 204.52.24.116, Dst: 104.18.2.35
Transmission Control Protocol, Src Port: 57394, Dst Port: 443, Seq: 0, Len: 0

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
      5 09:23:40.666095    104.18.2.35           204.52.24.116         TCP     
66     443 → 57394 [SYN, ACK] Seq=0 Ack=1 Win=64240 Len=0 MSS=1400 SACK_PERM
WS=8192 0.005460

Frame 5: 66 bytes on wire (528 bits), 66 bytes captured (528 bits)
Ethernet II, Src: Mellanox_4a:c0:fd (9c:05:91:4a:c0:fd), Dst: 4e:42:14:a1:2a:fb
(4e:42:14:a1:2a:fb)
Internet Protocol Version 4, Src: 104.18.2.35, Dst: 204.52.24.116
Transmission Control Protocol, Src Port: 443, Dst Port: 57394, Seq: 0, Ack: 1,
Len: 0

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
      6 09:23:40.666194    204.52.24.116         104.18.2.35           TCP     
58     57394 → 443 [ACK] Seq=1 Ack=1 Win=45056 Len=0                 0.000099

Frame 6: 58 bytes on wire (464 bits), 58 bytes captured (464 bits)
Ethernet II, Src: 4e:42:14:a1:2a:fb (4e:42:14:a1:2a:fb), Dst: IETF-VRRP-VRID_ff
(00:00:5e:00:01:ff)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
Internet Protocol Version 4, Src: 204.52.24.116, Dst: 104.18.2.35
Transmission Control Protocol, Src Port: 57394, Dst Port: 443, Seq: 1, Ack: 1,
Len: 0

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
      8 09:23:55.673177    104.18.2.35           204.52.24.116         TCP     
60     443 → 57394 [FIN, ACK] Seq=1 Ack=1 Win=65536 Len=0            12.696825

Frame 8: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
Ethernet II, Src: Mellanox_4a:c0:fd (9c:05:91:4a:c0:fd), Dst: 4e:42:14:a1:2a:fb
(4e:42:14:a1:2a:fb)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
Internet Protocol Version 4, Src: 104.18.2.35, Dst: 204.52.24.116
Transmission Control Protocol, Src Port: 443, Dst Port: 57394, Seq: 1, Ack: 1,
Len: 0

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
      9 09:23:55.676533    204.52.24.116         104.18.2.35           TLSv1   
65     [TCP Previous segment not captured] , Alert (Level: Fatal, Description:
Decode Error) 0.003356

Frame 9: 65 bytes on wire (520 bits), 65 bytes captured (520 bits)
Ethernet II, Src: 4e:42:14:a1:2a:fb (4e:42:14:a1:2a:fb), Dst: IETF-VRRP-VRID_ff
(00:00:5e:00:01:ff)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
Internet Protocol Version 4, Src: 204.52.24.116, Dst: 104.18.2.35
Transmission Control Protocol, Src Port: 57394, Dst Port: 443, Seq: 438, Ack:
2, Len: 7
Transport Layer Security
    TLSv1 Record Layer: Alert (Level: Fatal, Description: Decode Error)
        Content Type: Alert (21)
        Version: TLS 1.0 (0x0301)
        Length: 2
        Alert Message
            Level: Fatal (2)
            Description: Decode Error (50)

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
     10 09:23:55.681947    104.18.2.35           204.52.24.116         TCP     
56     443 → 57394 [RST] Seq=2 Win=0 Len=0                           0.005414

Frame 10: 56 bytes on wire (448 bits), 56 bytes captured (448 bits)
Ethernet II, Src: Mellanox_4a:c0:fd (9c:05:91:4a:c0:fd), Dst: 4e:42:14:a1:2a:fb
(4e:42:14:a1:2a:fb)
Internet Protocol Version 4, Src: 104.18.2.35, Dst: 204.52.24.116
Transmission Control Protocol, Src Port: 443, Dst Port: 57394, Seq: 2, Len: 0

No.     Time               Source                Destination           Protocol
Length Info                                                            Delta
     14 09:24:08.064432    172.27.18.244         104.18.2.35           TLSv1   
502    Client Hello, Alert (Level: Fatal, Description: Decode Error)   2.362983

Frame 14: 502 bytes on wire (4016 bits), 502 bytes captured (4016 bits)
Ethernet II, Src: 4e:42:14:a1:2a:fb (4e:42:14:a1:2a:fb), Dst: IETF-VRRP-VRID_ff
(00:00:5e:00:01:ff)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
Internet Protocol Version 4, Src: 172.27.18.244, Dst: 104.18.2.35
Transmission Control Protocol, Src Port: 57394, Dst Port: 443, Seq: 1, Ack: 1,
Len: 444
Transport Layer Security
    TLSv1 Record Layer: Handshake Protocol: Client Hello
        Content Type: Handshake (22)
        Version: TLS 1.0 (0x0301)
        Length: 432
        Handshake Protocol: Client Hello
    TLSv1 Record Layer: Alert (Level: Fatal, Description: Decode Error)
        Content Type: Alert (21)
        Version: TLS 1.0 (0x0301)
        Length: 2
        Alert Message
            Level: Fatal (2)
            Description: Decode Error (50)

```

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