146 lines
3.9 KiB
Go
146 lines
3.9 KiB
Go
package server
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import (
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"fmt"
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"io"
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"os"
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"strings"
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)
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const (
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// According to http://man7.org/linux/man-pages/man5/resolv.conf.5.html:
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// "The search list is currently limited to six domains with a total of 256 characters."
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maxDNSSearches = 6
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)
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func copyFile(src, dest string) error {
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in, err := os.Open(src)
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if err != nil {
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return err
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}
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defer in.Close()
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out, err := os.Create(dest)
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if err != nil {
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return err
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}
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defer out.Close()
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_, err = io.Copy(out, in)
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return err
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}
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func removeFile(path string) error {
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if _, err := os.Stat(path); err == nil {
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if err := os.Remove(path); err != nil {
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return err
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}
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}
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return nil
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}
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func parseDNSOptions(servers, searches, options []string, path string) error {
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nServers := len(servers)
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nSearches := len(searches)
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nOptions := len(options)
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if nServers == 0 && nSearches == 0 && nOptions == 0 {
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return copyFile("/etc/resolv.conf", path)
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}
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if nSearches > maxDNSSearches {
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return fmt.Errorf("DNSOption.Searches has more than 6 domains")
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}
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f, err := os.Create(path)
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if err != nil {
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return err
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}
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defer f.Close()
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if nSearches > 0 {
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data := fmt.Sprintf("search %s\n", strings.Join(searches, " "))
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_, err = f.Write([]byte(data))
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if err != nil {
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return err
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}
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}
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if nServers > 0 {
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data := fmt.Sprintf("nameserver %s\n", strings.Join(servers, "\nnameserver "))
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_, err = f.Write([]byte(data))
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if err != nil {
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return err
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}
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}
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if nOptions > 0 {
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data := fmt.Sprintf("options %s\n", strings.Join(options, " "))
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_, err = f.Write([]byte(data))
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if err != nil {
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return err
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}
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}
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return nil
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}
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// TODO: remove sysctl extraction related code here, instead we import from k8s directly.
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const (
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// SysctlsPodAnnotationKey represents the key of sysctls which are set for the infrastructure
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// container of a pod. The annotation value is a comma separated list of sysctl_name=value
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// key-value pairs. Only a limited set of whitelisted and isolated sysctls is supported by
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// the kubelet. Pods with other sysctls will fail to launch.
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SysctlsPodAnnotationKey string = "security.alpha.kubernetes.io/sysctls"
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// UnsafeSysctlsPodAnnotationKey represents the key of sysctls which are set for the infrastructure
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// container of a pod. The annotation value is a comma separated list of sysctl_name=value
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// key-value pairs. Unsafe sysctls must be explicitly enabled for a kubelet. They are properly
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// namespaced to a pod or a container, but their isolation is usually unclear or weak. Their use
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// is at-your-own-risk. Pods that attempt to set an unsafe sysctl that is not enabled for a kubelet
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// will fail to launch.
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UnsafeSysctlsPodAnnotationKey string = "security.alpha.kubernetes.io/unsafe-sysctls"
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)
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// Sysctl defines a kernel parameter to be set
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type Sysctl struct {
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// Name of a property to set
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Name string `json:"name"`
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// Value of a property to set
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Value string `json:"value"`
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}
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// SysctlsFromPodAnnotations parses the sysctl annotations into a slice of safe Sysctls
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// and a slice of unsafe Sysctls. This is only a convenience wrapper around
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// SysctlsFromPodAnnotation.
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func SysctlsFromPodAnnotations(a map[string]string) ([]Sysctl, []Sysctl, error) {
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safe, err := SysctlsFromPodAnnotation(a[SysctlsPodAnnotationKey])
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if err != nil {
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return nil, nil, err
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}
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unsafe, err := SysctlsFromPodAnnotation(a[UnsafeSysctlsPodAnnotationKey])
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if err != nil {
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return nil, nil, err
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}
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return safe, unsafe, nil
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}
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// SysctlsFromPodAnnotation parses an annotation value into a slice of Sysctls.
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func SysctlsFromPodAnnotation(annotation string) ([]Sysctl, error) {
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if len(annotation) == 0 {
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return nil, nil
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}
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kvs := strings.Split(annotation, ",")
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sysctls := make([]Sysctl, len(kvs))
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for i, kv := range kvs {
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cs := strings.Split(kv, "=")
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if len(cs) != 2 || len(cs[0]) == 0 {
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return nil, fmt.Errorf("sysctl %q not of the format sysctl_name=value", kv)
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}
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sysctls[i].Name = cs[0]
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sysctls[i].Value = cs[1]
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}
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return sysctls, nil
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}
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