CVE-2025-37959

When bpfredirectpeer is used to redirect packets to a device in another network namespace, the skb isn't scrubbed. That can lead skb information from one namespace to be "misused" in another namespace.

As one example, this is causing Cilium to drop traffic when using bpfredirectpeer to redirect packets that just went through IPsec decryption to a container namespace. The following pwru trace shows (1) the packet path from the host's XFRM layer to the container's XFRM layer where it's dropped and (2) the number of active skb extensions at each function.

NETNS       MARK  IFACE  TUPLE                                FUNC
4026533547  d00   eth0   10.244.3.124:35473->10.244.2.158:53  xfrm_rcv_cb
                         .active_extensions = (__u8)2,
4026533547  d00   eth0   10.244.3.124:35473->10.244.2.158:53  xfrm4_rcv_cb
                         .active_extensions = (__u8)2,
4026533547  d00   eth0   10.244.3.124:35473->10.244.2.158:53  gro_cells_receive
                         .active_extensions = (__u8)2,
[...]
4026533547  0     eth0   10.244.3.124:35473->10.244.2.158:53  skb_do_redirect
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  ip_rcv
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  ip_rcv_core
                         .active_extensions = (__u8)2,
[...]
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  udp_queue_rcv_one_skb
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  __xfrm_policy_check
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  __xfrm_decode_session
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  security_xfrm_decode_session
                         .active_extensions = (__u8)2,
4026534999  0     eth0   10.244.3.124:35473->10.244.2.158:53  kfree_skb_reason(SKB_DROP_REASON_XFRM_POLICY)
                         .active_extensions = (__u8)2,

In this case, there are no XFRM policies in the container's network namespace so the drop is unexpected. When we decrypt the IPsec packet, the XFRM state used for decryption is set in the skb extensions. This information is preserved across the netns switch. When we reach the XFRM policy check in the container's netns, _xfrmpolicycheck drops the packet with LINUXMIB_XFRMINNOPOLS because a (container-side) XFRM policy can't be found that matches the (host-side) XFRM state used for decryption.

This patch fixes this by scrubbing the packet when using bpfredirectpeer, as is done on typical netns switches via veth devices except skb->mark and skb->tstamp are not zeroed.

References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

9aa1206e8f48222f35a0c809f33b2f4aaa1e2661

Fixed

de1067cc8cf0e8c11ae20cbe5c467aef19d04ded

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

9aa1206e8f48222f35a0c809f33b2f4aaa1e2661

Fixed

355b0526336c0bf2bf7feaca033568ede524f763

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

9aa1206e8f48222f35a0c809f33b2f4aaa1e2661

Fixed

b37e54259cab4f78b53953d6f6268b85f07bef3e

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

9aa1206e8f48222f35a0c809f33b2f4aaa1e2661

Fixed

9e15ef33ba39fb6d9d1f51445957f16983a9437a

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

9aa1206e8f48222f35a0c809f33b2f4aaa1e2661

Fixed

c4327229948879814229b46aa26a750718888503

Affected versions

v5.*

v5.10

v5.10-rc1

v5.10-rc2

v5.10-rc3

v5.10-rc4

v5.10-rc5

v5.10-rc6

v5.10-rc7

v5.11

v5.11-rc1

v5.11-rc2

v5.11-rc3

v5.11-rc4

v5.11-rc5

v5.11-rc6

v5.11-rc7

v5.12

v5.12-rc1

v5.12-rc1-dontuse

v5.12-rc2

v5.12-rc3

v5.12-rc4

v5.12-rc5

v5.12-rc6

v5.12-rc7

v5.12-rc8

v5.13

v5.13-rc1

v5.13-rc2

v5.13-rc3

v5.13-rc4

v5.13-rc5

v5.13-rc6

v5.13-rc7

v5.14

v5.14-rc1

v5.14-rc2

v5.14-rc3

v5.14-rc4

v5.14-rc5

v5.14-rc6

v5.14-rc7

v5.15

v5.15-rc1

v5.15-rc2

v5.15-rc3

v5.15-rc4

v5.15-rc5

v5.15-rc6

v5.15-rc7

v5.16

v5.16-rc1

v5.16-rc2

v5.16-rc3

v5.16-rc4

v5.16-rc5

v5.16-rc6

v5.16-rc7

v5.16-rc8

v5.17

v5.17-rc1

v5.17-rc2

v5.17-rc3

v5.17-rc4

v5.17-rc5

v5.17-rc6

v5.17-rc7

v5.17-rc8

v5.18

v5.18-rc1

v5.18-rc2

v5.18-rc3

v5.18-rc4

v5.18-rc5

v5.18-rc6

v5.18-rc7

v5.19

v5.19-rc1

v5.19-rc2

v5.19-rc3

v5.19-rc4

v5.19-rc5

v5.19-rc6

v5.19-rc7

v5.19-rc8

v5.9

v5.9-rc7

v5.9-rc8

v6.*

v6.0

v6.0-rc1

v6.0-rc2

v6.0-rc3

v6.0-rc4

v6.0-rc5

v6.0-rc6

v6.0-rc7

v6.1

v6.1-rc1

v6.1-rc2

v6.1-rc3

v6.1-rc4

v6.1-rc5

v6.1-rc6

v6.1-rc7

v6.1-rc8

v6.1.1

v6.1.10

v6.1.100

v6.1.101

v6.1.102

v6.1.103

v6.1.104

v6.1.105

v6.1.106

v6.1.107

v6.1.108

v6.1.109

v6.1.11

v6.1.110

v6.1.111

v6.1.112

v6.1.113

v6.1.114

v6.1.115

v6.1.116

v6.1.117

v6.1.118

v6.1.119

v6.1.12

v6.1.120

v6.1.121

v6.1.122

v6.1.123

v6.1.124

v6.1.125

v6.1.126

v6.1.127

v6.1.128

v6.1.129

v6.1.13

v6.1.130

v6.1.131

v6.1.132

v6.1.133

v6.1.134

v6.1.135

v6.1.136

v6.1.137

v6.1.138

v6.1.14

v6.1.15

v6.1.16

v6.1.17

v6.1.18

v6.1.19

v6.1.2

v6.1.20

v6.1.21

v6.1.22

v6.1.23

v6.1.24

v6.1.25

v6.1.26

v6.1.27

v6.1.28

v6.1.29

v6.1.3

v6.1.30

v6.1.31

v6.1.32

v6.1.33

v6.1.34

v6.1.35

v6.1.36

v6.1.37

v6.1.38

v6.1.39

v6.1.4

v6.1.40

v6.1.41

v6.1.42

v6.1.43

v6.1.44

v6.1.45

v6.1.46

v6.1.47

v6.1.48

v6.1.49

v6.1.5

v6.1.50

v6.1.51

v6.1.52

v6.1.53

v6.1.54

v6.1.55

v6.1.56

v6.1.57

v6.1.58

v6.1.59

v6.1.6

v6.1.60

v6.1.61

v6.1.62

v6.1.63

v6.1.64

v6.1.65

v6.1.66

v6.1.67

v6.1.68

v6.1.69

v6.1.7

v6.1.70

v6.1.71

v6.1.72

v6.1.73

v6.1.74

v6.1.75

v6.1.76

v6.1.77

v6.1.78

v6.1.79

v6.1.8

v6.1.80

v6.1.81

v6.1.82

v6.1.83

v6.1.84

v6.1.85

v6.1.86

v6.1.87

v6.1.88

v6.1.89

v6.1.9

v6.1.90

v6.1.91

v6.1.92

v6.1.93

v6.1.94

v6.1.95

v6.1.96

v6.1.97

v6.1.98

v6.1.99

v6.10

v6.10-rc1

v6.10-rc2

v6.10-rc3

v6.10-rc4

v6.10-rc5

v6.10-rc6

v6.10-rc7

v6.11

v6.11-rc1

v6.11-rc2

v6.11-rc3

v6.11-rc4

v6.11-rc5

v6.11-rc6

v6.11-rc7

v6.12

v6.12-rc1

v6.12-rc2

v6.12-rc3

v6.12-rc4

v6.12-rc5

v6.12-rc6

v6.12-rc7

v6.12.1

v6.12.10

v6.12.11

v6.12.12

v6.12.13

v6.12.14

v6.12.15

v6.12.16

v6.12.17

v6.12.18

v6.12.19

v6.12.2

v6.12.20

v6.12.21

v6.12.22

v6.12.23

v6.12.24

v6.12.25

v6.12.26

v6.12.27

v6.12.28

v6.12.3

v6.12.4

v6.12.5

v6.12.6

v6.12.7

v6.12.8

v6.12.9

v6.13

v6.13-rc1

v6.13-rc2

v6.13-rc3

v6.13-rc4

v6.13-rc5

v6.13-rc6

v6.13-rc7

v6.14

v6.14-rc1

v6.14-rc2

v6.14-rc3

v6.14-rc4

v6.14-rc5

v6.14-rc6

v6.14-rc7

v6.14.1

v6.14.2

v6.14.3

v6.14.4

v6.14.5

v6.14.6

v6.15-rc1

v6.15-rc2

v6.15-rc3

v6.15-rc4

v6.2

v6.2-rc1

v6.2-rc2

v6.2-rc3

v6.2-rc4

v6.2-rc5

v6.2-rc6

v6.2-rc7

v6.2-rc8

v6.3

v6.3-rc1

v6.3-rc2

v6.3-rc3

v6.3-rc4

v6.3-rc5

v6.3-rc6

v6.3-rc7

v6.4

v6.4-rc1

v6.4-rc2

v6.4-rc3

v6.4-rc4

v6.4-rc5

v6.4-rc6

v6.4-rc7

v6.5

v6.5-rc1

v6.5-rc2

v6.5-rc3

v6.5-rc4

v6.5-rc5

v6.5-rc6

v6.5-rc7

v6.6

v6.6-rc1

v6.6-rc2

v6.6-rc3

v6.6-rc4

v6.6-rc5

v6.6-rc6

v6.6-rc7

v6.6.1

v6.6.10

v6.6.11

v6.6.12

v6.6.13

v6.6.14

v6.6.15

v6.6.16

v6.6.17

v6.6.18

v6.6.19

v6.6.2

v6.6.20

v6.6.21

v6.6.22

v6.6.23

v6.6.24

v6.6.25

v6.6.26

v6.6.27

v6.6.28

v6.6.29

v6.6.3

v6.6.30

v6.6.31

v6.6.32

v6.6.33

v6.6.34

v6.6.35

v6.6.36

v6.6.37

v6.6.38

v6.6.39

v6.6.4

v6.6.40

v6.6.41

v6.6.42

v6.6.43

v6.6.44

v6.6.45

v6.6.46

v6.6.47

v6.6.48

v6.6.49

v6.6.5

v6.6.50

v6.6.51

v6.6.52

v6.6.53

v6.6.54

v6.6.55

v6.6.56

v6.6.57

v6.6.58

v6.6.59

v6.6.6

v6.6.60

v6.6.61

v6.6.62

v6.6.63

v6.6.64

v6.6.65

v6.6.66

v6.6.67

v6.6.68

v6.6.69

v6.6.7

v6.6.70

v6.6.71

v6.6.72

v6.6.73

v6.6.74

v6.6.75

v6.6.76

v6.6.77

v6.6.78

v6.6.79

v6.6.8

v6.6.80

v6.6.81

v6.6.82

v6.6.83

v6.6.84

v6.6.85

v6.6.86

v6.6.87

v6.6.88

v6.6.89

v6.6.9

v6.6.90

v6.7

v6.7-rc1

v6.7-rc2

v6.7-rc3

v6.7-rc4

v6.7-rc5

v6.7-rc6

v6.7-rc7

v6.7-rc8

v6.8

v6.8-rc1

v6.8-rc2

v6.8-rc3

v6.8-rc4

v6.8-rc5

v6.8-rc6

v6.8-rc7

v6.9

v6.9-rc1

v6.9-rc2

v6.9-rc3

v6.9-rc4

v6.9-rc5

v6.9-rc6

v6.9-rc7

Linux / Kernel

Package

Name: Kernel

Affected ranges

Type: ECOSYSTEM
Events: Introduced

5.10.0

Fixed

6.1.139

Type: ECOSYSTEM
Events: Introduced

6.2.0

Fixed

6.6.91

Type: ECOSYSTEM
Events: Introduced

6.7.0

Fixed

6.12.29

Type: ECOSYSTEM
Events: Introduced

6.13.0

Fixed

6.14.7