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Relative symlinks don't work with --device argument

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This fix tries to address the issue raised in #22271 where
relative symlinks don't work with --device argument.

Previously, the symlinks in --device was implemneted (#20684)
with `os.Readlink()` which does not resolve if the linked
target is a relative path. In this fix, `filepath.EvalSymlinks()`
has been used which will reolve correctly with relative
paths.

An additional test case has been added to the existing
`TestRunDeviceSymlink` to cover changes in this fix.

This fix is related to #13840 and #20684, #22271.
This fix fixes #22271.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
This commit is contained in:
Yong Tang 2016-04-23 08:00:57 -07:00
parent 66eb91463a
commit 632b314b23
2 changed files with 14 additions and 2 deletions
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2
daemon/container_operations_unix.go
View file

@ -311,7 +311,7 @@ func getDevicesFromPath(deviceMapping containertypes.DeviceMapping) (devs []spec
// check if it is a symbolic link
if src, e := os.Lstat(deviceMapping.PathOnHost); e == nil && src.Mode()&os.ModeSymlink == os.ModeSymlink {
if linkedPathOnHost, e := os.Readlink(deviceMapping.PathOnHost); e == nil {
if linkedPathOnHost, e := filepath.EvalSymlinks(deviceMapping.PathOnHost); e == nil {
resolvedPathOnHost = linkedPathOnHost
}
}

14
integration-cli/docker_cli_run_unix_test.go
View file

@ -1021,7 +1021,7 @@ func (s *DockerSuite) TestRunSeccompWithDefaultProfile(c *check.C) {
c.Assert(strings.TrimSpace(out), checker.Equals, "unshare: unshare failed: Operation not permitted")
}
// TestRunDeviceSymlink checks run with device that follows symlink (#13840)
// TestRunDeviceSymlink checks run with device that follows symlink (#13840 and #22271)
func (s *DockerSuite) TestRunDeviceSymlink(c *check.C) {
testRequires(c, DaemonIsLinux, NotUserNamespace, NotArm, SameHostDaemon)
if _, err := os.Stat("/dev/zero"); err != nil {
@ -1048,6 +1048,14 @@ func (s *DockerSuite) TestRunDeviceSymlink(c *check.C) {
err = os.Symlink(tmpFile, symFile)
c.Assert(err, checker.IsNil)
// Create a symbolic link to /dev/zero, this time with a relative path (#22271)
err = os.Symlink("zero", "/dev/symzero")
if err != nil {
c.Fatal("/dev/symzero creation failed")
}
// We need to remove this symbolic link here as it is created in /dev/, not temporary directory as above
defer os.Remove("/dev/symzero")
// md5sum of 'dd if=/dev/zero bs=4K count=8' is bb7df04e1b0a2570657527a7e108ae23
out, _ := dockerCmd(c, "run", "--device", symZero+":/dev/symzero", "busybox", "sh", "-c", "dd if=/dev/symzero bs=4K count=8 | md5sum")
c.Assert(strings.Trim(out, "\r\n"), checker.Contains, "bb7df04e1b0a2570657527a7e108ae23", check.Commentf("expected output bb7df04e1b0a2570657527a7e108ae23"))
@ -1056,6 +1064,10 @@ func (s *DockerSuite) TestRunDeviceSymlink(c *check.C) {
out, _, err = dockerCmdWithError("run", "--device", symFile+":/dev/symzero", "busybox", "sh", "-c", "dd if=/dev/symzero bs=4K count=8 | md5sum")
c.Assert(err, check.NotNil)
c.Assert(strings.Trim(out, "\r\n"), checker.Contains, "not a device node", check.Commentf("expected output 'not a device node'"))
// md5sum of 'dd if=/dev/zero bs=4K count=8' is bb7df04e1b0a2570657527a7e108ae23 (this time check with relative path backed, see #22271)
out, _ = dockerCmd(c, "run", "--device", "/dev/symzero:/dev/symzero", "busybox", "sh", "-c", "dd if=/dev/symzero bs=4K count=8 | md5sum")
c.Assert(strings.Trim(out, "\r\n"), checker.Contains, "bb7df04e1b0a2570657527a7e108ae23", check.Commentf("expected output bb7df04e1b0a2570657527a7e108ae23"))
}
// TestRunPidsLimit makes sure the pids cgroup is set with --pids-limit