kernel: enable xfrm_interface

[rlmenge]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

---

Summary

This PR enables Linux XFRM interfaces to allow creating xfrmN devices for IPsec policy routing and namespace/VRF separation. It turns on CONFIG_XFRM_INTERFACE in the kernel config (module autoloads on use). No behavior change by default; it simply unlocks IPsec scenarios that require if_id steering.

Impact: none for existing users; new capability for per-tenant/VRF IPsec paths

Change Log

• enable CONFIG_XFRM_INTERFACE, build/install module

Does this affect the toolchain?

YES

Associated issues

• https://microsoft.visualstudio.com/OS/_workitems/edit/60419886

Test Methodology

• https://dev.azure.com/mariner-org/mariner/_build/results?buildId=1021426&view=results

x86

*** Smoke Testing Kernel 6.6.119.3-2.azl3 (est. < 1 min) ***
OS Version: NAME="Microsoft Azure Linux"
VERSION="3.0.20251206"
ID=azurelinux
VERSION_ID="3.0"
PRETTY_NAME="Microsoft Azure Linux 3.0"
ANSI_COLOR="1;34"
HOME_URL="https://aka.ms/azurelinux"
BUG_REPORT_URL="https://aka.ms/azurelinux"
SUPPORT_URL="https://aka.ms/azurelinux"
PASS: Kernel version matches the running kernel version.
PASS: eth0 interface is up.
PASS: iptables service is running.
Boot times:
Startup finished in 4.272s (kernel) + 1.758s (initrd) + 7.052s (userspace) = 13.083s 
graphical.target reached after 6.670s in userspace.
Kernel size:
-rw------- 1 root root 15122432 Jan  8 00:00 /boot/vmlinuz-6.6.119.3-2.azl3
34932	/lib/modules/6.6.119.3-2.azl3
kernel memory:
MemTotal:       65951308 kB
MemFree:        65332560 kB
MemAvailable:   65082144 kB
Total memory:
               total        used        free      shared  buff/cache   available
Mem:           64405         848       63800           0         145       63556
Swap:              0           0           0

Arm64

*** Smoke Testing Kernel 6.6.119.3-2.azl3 (est. < 1 min) ***
OS Version: NAME="Microsoft Azure Linux"
VERSION="3.0.20251206"
ID=azurelinux
VERSION_ID="3.0"
PRETTY_NAME="Microsoft Azure Linux 3.0"
ANSI_COLOR="1;34"
HOME_URL="https://aka.ms/azurelinux"
BUG_REPORT_URL="https://aka.ms/azurelinux"
SUPPORT_URL="https://aka.ms/azurelinux"
PASS: Kernel version matches the running kernel version.
PASS: eth0 interface is up.
PASS: iptables service is running.
Boot times:
Startup finished in 1.285s (kernel) + 1.276s (initrd) + 6.113s (userspace) = 8.676s 
graphical.target reached after 5.872s in userspace.
Kernel size:
-rw------- 1 root root 48781824 Jan  8 00:09 /boot/vmlinuz-6.6.119.3-2.azl3
56792	/lib/modules/6.6.119.3-2.azl3
kernel memory:
MemTotal:       32797736 kB
MemFree:        32277440 kB
MemAvailable:   32114728 kB
Total memory:
               total        used        free      shared  buff/cache   available
Mem:           32029         667       31520           0         141       31362
Swap:              0           0           0

[christopherco]