missing kernel config check

[zouxianyu]

Environmental Info:
K3s Version:

k3s version v1.29.4+k3s1 (94e29e2)
go version go1.21.9

Node(s) CPU architecture, OS, and Version:

Linux master 5.10.110 #1 SMP Mon May 13 02:09:12 PDT 2024 aarch64 aarch64 aarch64 GNU/Linux

Cluster Configuration:

1 server, 1 agent

Describe the bug:

k3s won't start. Here are some error messages taken from journalctl -u k3s.

master k3s[2242]: E0515 06:41:43.060036    2242 proxier.go:1525] "Failed to execute iptables-restore" err=<
master k3s[2242]:         exit status 2: iptables-restore v1.8.7 (legacy): Couldn't load target `REJECT':No such file or directory
master k3s[2242]:
master k3s[2242]:         Error occurred at line: 9
master k3s[2242]:         Try `iptables-restore -h' or 'iptables-restore --help' for more information.
master k3s[2242]:  >

Linux kernel needs to enable CONFIG_IP_NF_TARGET_REJECT, but check-config.sh doesn't check for it.

Steps To Reproduce:

• Installed K3s

Expected behavior:

All Pods in the kube-system namespace run normally.

Actual behavior:

Some Pods don't work properly.

root@master:~$ kubectl get pod -A
NAMESPACE     NAME                                      READY   STATUS             RESTARTS         AGE
kube-system   coredns-7b6586dfcd-n6cn5                  0/1     Running            0                46m
kube-system   metrics-server-754c646885-vrbql           0/1     CrashLoopBackOff   12 (3m11s ago)   46m
kube-system   local-path-provisioner-77db45d49b-59fmt   0/1     CrashLoopBackOff   12 (3m19s ago)   46m
kube-system   helm-install-traefik-5skn2                0/1     CrashLoopBackOff   8 (3m5s ago)     46m
kube-system   helm-install-traefik-crd-r47zd            0/1     CrashLoopBackOff   8 (2m56s ago)    46m

Additional context / logs:

[mdrahman-suse]

Validated on master branch with commit cff6f7a

Environment

$ uname -a
Linux server1 6.2.0-1012-aws #12~22.04.1-Ubuntu SMP Thu Sep  7 16:00:15 UTC 2023 aarch64 aarch64 aarch64 GNU/Linux

Single server

Testing

• Install k3s
• Ensure cluster is up and running
• Run k3s check-config
• Validate CONFIG_IP_NF_TARGET_REJECT is present and enabled

Replication

$ k3s -v
k3s version v1.30.1+k3s1 (80978b5b)
go version go1.22.2

$ k3s check-config
cat: /sys/kernel/security/apparmor/profiles: Permission denied

Verifying binaries in /var/lib/rancher/k3s/data/019fb8bac4d619f2f3682a8aef4f460c4759bd4d1510b12b05b498936e75da14/bin:
- sha256sum: good
- links: good

System:
- /usr/sbin iptables v1.8.7 (nf_tables): ok
- swap: disabled
- routes: ok

Limits:
- /proc/sys/kernel/keys/root_maxkeys: 1000000

modprobe: FATAL: Module configs not found in directory /lib/modules/6.2.0-1012-aws
info: reading kernel config from /boot/config-6.2.0-1012-aws ...

Generally Necessary:
- cgroup hierarchy: cgroups V2 mounted, cpu|cpuset|memory controllers status: good
- /usr/sbin/apparmor_parser
apparmor: enabled and tools installed
- CONFIG_NAMESPACES: enabled
- CONFIG_NET_NS: enabled
- CONFIG_PID_NS: enabled
- CONFIG_IPC_NS: enabled
- CONFIG_UTS_NS: enabled
- CONFIG_CGROUPS: enabled
- CONFIG_CGROUP_PIDS: enabled
- CONFIG_CGROUP_CPUACCT: enabled
- CONFIG_CGROUP_DEVICE: enabled
- CONFIG_CGROUP_FREEZER: enabled
- CONFIG_CGROUP_SCHED: enabled
- CONFIG_CPUSETS: enabled
- CONFIG_MEMCG: enabled
- CONFIG_KEYS: enabled
- CONFIG_VETH: enabled (as module)
- CONFIG_BRIDGE: enabled (as module)
- CONFIG_BRIDGE_NETFILTER: enabled (as module)
- CONFIG_IP_NF_FILTER: enabled (as module)
- CONFIG_IP_NF_TARGET_MASQUERADE: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_ADDRTYPE: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_CONNTRACK: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_IPVS: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_MULTIPORT: enabled (as module)
- CONFIG_IP_NF_NAT: enabled (as module)
- CONFIG_NF_NAT: enabled (as module)
- CONFIG_POSIX_MQUEUE: enabled
...
STATUS: pass

Validation

$ k3s -v
k3s version v1.30.1+k3s-cff6f7aa (cff6f7aa)
go version go1.22.2

$ k3s check-config
cat: /sys/kernel/security/apparmor/profiles: Permission denied

Verifying binaries in /var/lib/rancher/k3s/data/93dbdeb1dc09ec65c4f3c32bec85f633fc72dd538f97dddd1607d03b428bb994/bin:
- sha256sum: good
- links: good

System:
- /usr/sbin iptables v1.8.7 (nf_tables): ok
- swap: disabled
- routes: ok

Limits:
- /proc/sys/kernel/keys/root_maxkeys: 1000000

modprobe: FATAL: Module configs not found in directory /lib/modules/6.2.0-1012-aws
info: reading kernel config from /boot/config-6.2.0-1012-aws ...

Generally Necessary:
- cgroup hierarchy: cgroups V2 mounted, cpu|cpuset|memory controllers status: good
- /usr/sbin/apparmor_parser
apparmor: enabled and tools installed
- CONFIG_NAMESPACES: enabled
- CONFIG_NET_NS: enabled
- CONFIG_PID_NS: enabled
- CONFIG_IPC_NS: enabled
- CONFIG_UTS_NS: enabled
- CONFIG_CGROUPS: enabled
- CONFIG_CGROUP_PIDS: enabled
- CONFIG_CGROUP_CPUACCT: enabled
- CONFIG_CGROUP_DEVICE: enabled
- CONFIG_CGROUP_FREEZER: enabled
- CONFIG_CGROUP_SCHED: enabled
- CONFIG_CPUSETS: enabled
- CONFIG_MEMCG: enabled
- CONFIG_KEYS: enabled
- CONFIG_VETH: enabled (as module)
- CONFIG_BRIDGE: enabled (as module)
- CONFIG_BRIDGE_NETFILTER: enabled (as module)
- CONFIG_IP_NF_FILTER: enabled (as module)
- CONFIG_IP_NF_TARGET_MASQUERADE: enabled (as module)
- CONFIG_IP_NF_TARGET_REJECT: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_ADDRTYPE: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_CONNTRACK: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_IPVS: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled (as module)
- CONFIG_NETFILTER_XT_MATCH_MULTIPORT: enabled (as module)
- CONFIG_IP_NF_NAT: enabled (as module)
- CONFIG_NF_NAT: enabled (as module)
- CONFIG_POSIX_MQUEUE: enabled
...
STATUS: pass