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6993e891d1
Following #19995 and #17409 this PR enables skipping userns re-mapping when creating a container (or when executing a command). Thus, enabling privileged containers running side by side with userns remapped containers. The feature is enabled by specifying ```--userns:host```, which will not remapped the user if userns are applied. If this flag is not specified, the existing behavior (which blocks specific privileged operation) remains. Signed-off-by: Liron Levin <liron@twistlock.com>
86 lines
3.5 KiB
Go
86 lines
3.5 KiB
Go
// +build !windows
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package main
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import (
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"fmt"
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"io/ioutil"
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"os"
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"os/exec"
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"path/filepath"
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"strconv"
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"strings"
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"github.com/docker/docker/pkg/integration/checker"
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"github.com/docker/docker/pkg/system"
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"github.com/go-check/check"
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)
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// user namespaces test: run daemon with remapped root setting
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// 1. validate uid/gid maps are set properly
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// 2. verify that files created are owned by remapped root
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func (s *DockerDaemonSuite) TestDaemonUserNamespaceRootSetting(c *check.C) {
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testRequires(c, DaemonIsLinux, SameHostDaemon, UserNamespaceInKernel)
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c.Assert(s.d.StartWithBusybox("--userns-remap", "default"), checker.IsNil)
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tmpDir, err := ioutil.TempDir("", "userns")
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c.Assert(err, checker.IsNil)
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defer os.RemoveAll(tmpDir)
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// we need to find the uid and gid of the remapped root from the daemon's root dir info
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uidgid := strings.Split(filepath.Base(s.d.root), ".")
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c.Assert(uidgid, checker.HasLen, 2, check.Commentf("Should have gotten uid/gid strings from root dirname: %s", filepath.Base(s.d.root)))
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uid, err := strconv.Atoi(uidgid[0])
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c.Assert(err, checker.IsNil, check.Commentf("Can't parse uid"))
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gid, err := strconv.Atoi(uidgid[1])
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c.Assert(err, checker.IsNil, check.Commentf("Can't parse gid"))
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// writable by the remapped root UID/GID pair
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c.Assert(os.Chown(tmpDir, uid, gid), checker.IsNil)
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out, err := s.d.Cmd("run", "-d", "--name", "userns", "-v", tmpDir+":/goofy", "busybox", "sh", "-c", "touch /goofy/testfile; top")
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c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
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user := s.findUser(c, "userns")
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c.Assert(uidgid[0], checker.Equals, user)
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pid, err := s.d.Cmd("inspect", "--format='{{.State.Pid}}'", "userns")
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c.Assert(err, checker.IsNil, check.Commentf("Could not inspect running container: out: %q", pid))
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// check the uid and gid maps for the PID to ensure root is remapped
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// (cmd = cat /proc/<pid>/uid_map | grep -E '0\s+9999\s+1')
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out, rc1, err := runCommandPipelineWithOutput(
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exec.Command("cat", "/proc/"+strings.TrimSpace(pid)+"/uid_map"),
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exec.Command("grep", "-E", fmt.Sprintf("0[[:space:]]+%d[[:space:]]+", uid)))
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c.Assert(rc1, checker.Equals, 0, check.Commentf("Didn't match uid_map: output: %s", out))
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out, rc2, err := runCommandPipelineWithOutput(
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exec.Command("cat", "/proc/"+strings.TrimSpace(pid)+"/gid_map"),
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exec.Command("grep", "-E", fmt.Sprintf("0[[:space:]]+%d[[:space:]]+", gid)))
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c.Assert(rc2, checker.Equals, 0, check.Commentf("Didn't match gid_map: output: %s", out))
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// check that the touched file is owned by remapped uid:gid
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stat, err := system.Stat(filepath.Join(tmpDir, "testfile"))
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c.Assert(err, checker.IsNil)
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c.Assert(stat.UID(), checker.Equals, uint32(uid), check.Commentf("Touched file not owned by remapped root UID"))
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c.Assert(stat.GID(), checker.Equals, uint32(gid), check.Commentf("Touched file not owned by remapped root GID"))
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// use host usernamespace
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out, err = s.d.Cmd("run", "-d", "--name", "userns_skip", "--userns", "host", "busybox", "sh", "-c", "touch /goofy/testfile; top")
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c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
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user = s.findUser(c, "userns_skip")
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// userns are skipped, user is root
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c.Assert(user, checker.Equals, "root")
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}
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// findUser finds the uid or name of the user of the first process that runs in a container
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func (s *DockerDaemonSuite) findUser(c *check.C, container string) string {
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out, err := s.d.Cmd("top", container)
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c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
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rows := strings.Split(out, "\n")
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if len(rows) < 2 {
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// No process rows founds
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c.FailNow()
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}
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return strings.Fields(rows[1])[0]
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}
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