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47 lines
1.5 KiB
Go
47 lines
1.5 KiB
Go
package child
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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"github.com/pkg/errors"
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"github.com/rootless-containers/rootlesskit/pkg/common"
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)
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func generateResolvConf(dns string) []byte {
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return []byte("nameserver " + dns + "\n")
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}
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func writeResolvConf(dns string) error {
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// remove copied-up link
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_ = os.Remove("/etc/resolv.conf")
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if err := ioutil.WriteFile("/etc/resolv.conf", generateResolvConf(dns), 0644); err != nil {
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return errors.Wrapf(err, "writing %s", "/etc/resolv.conf")
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}
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return nil
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}
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// mountResolvConf does not work when /etc/resolv.conf is a managed by
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// systemd or NetworkManager, because our bind-mounted /etc/resolv.conf (in our namespaces)
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// is unexpectedly unmounted when /etc/resolv.conf is recreated in the initial initial namespace.
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//
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// If /etc/resolv.conf is a symlink, e.g. to ../run/systemd/resolve/stub-resolv.conf,
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// our bind-mounted /etc/resolv.conf is still unmounted when /run/systemd/resolve/stub-resolv.conf is recreated.
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//
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// Use writeResolvConf with copying-up /etc for most cases.
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func mountResolvConf(tempDir, dns string) error {
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myResolvConf := filepath.Join(tempDir, "resolv.conf")
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if err := ioutil.WriteFile(myResolvConf, generateResolvConf(dns), 0644); err != nil {
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return errors.Wrapf(err, "writing %s", myResolvConf)
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}
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cmds := [][]string{
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{"mount", "--bind", myResolvConf, "/etc/resolv.conf"},
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}
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if err := common.Execs(os.Stderr, os.Environ(), cmds); err != nil {
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return errors.Wrapf(err, "executing %v", cmds)
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}
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return nil
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}
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