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OCPBUGS-11437: MCO keeps the pull secret to .orig file once it replaced #3759

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merged 1 commit into from
Sep 18, 2023
Merged

OCPBUGS-11437: MCO keeps the pull secret to .orig file once it replaced #3759

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78 changes: 74 additions & 4 deletions pkg/daemon/file_writers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (
"os/user"
"path/filepath"
"strconv"
"strings"

ign3types "github.com/coreos/ignition/v2/config/v3_4/types"
"github.com/google/renameio"
Expand Down Expand Up @@ -45,12 +46,81 @@ func noOrigFileStampName(fpath string) string {
return filepath.Join(noOrigParentDir(), fpath+".mcdnoorig")
}

func isFileOwnedByRPMPkg(fpath string) (bool, bool, error) {
// The first bool returns false if rpm exists, and true otherwise (indicating other Linux distros or Mac).
// We would like to skip orig file creation and preservation for [first bool = true] cases.
// The second bool returns true if the given path is owned by the rpm pkg.

// Check whether the underlying OS is Fedora/RHEL, skip the rest and return if not (e.g. Mac -> no rpm)
// If we cannot find the rpm binary, return an error.
path, err := exec.LookPath("rpm")
if err != nil {
return true, false, err
}

// Check whether the given path is owned by an rpm pkg
cmd := exec.Command(path, "-qf", fpath)
out, err := cmd.CombinedOutput()

if err == nil && cmd.ProcessState.ExitCode() == 0 {
return false, true, nil
}
fileNotOwnedMsg := fmt.Sprintf("file %s is not owned by any package", fpath)
if strings.Contains(string(out), fileNotOwnedMsg) {
return false, false, nil
}
return false, false, fmt.Errorf("command %q returned with unexpected error: %s: %w", cmd, string(out), err)
}

func createOrigFile(fromPath, fpath string) error {
if _, err := os.Stat(noOrigFileStampName(fpath)); err == nil {
// we already created the no orig file for this default file
return nil
orig := false

// https://issues.redhat.com/browse/OCPBUGS-11437
// MCO keeps the pull secret to .orig file once it replaced
// Adapt a check used in function deleteStaleData for backwards compatibility: basically if the file doesn't
// exist in /usr/etc (on FCOS/RHCOS) and no rpm is claiming it, we assume the orig file doesn't need to be created.
// Only do the check for existing files because files that wasn't present on disk before MCD took over will never
// be files that were shipped _with_ the underlying OS (e.g. a default chrony config).
if _, err := os.Stat(fpath); err == nil {
rpmNotFound, isOwned, err := isFileOwnedByRPMPkg(fpath)
if isOwned {
// File is owned by an rpm
orig = true
} else if !isOwned && (err == nil) {
// Run on Fedora/RHEL - check whether the file exist in /usr/etc (on FCOS/RHCOS)
if strings.HasPrefix(fpath, "/etc") {
if _, err := os.Stat(withUsrPath(fpath)); err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
orig = true
}
}
} else if rpmNotFound {
// Run on non-Fedora/RHEL machine
klog.Infof("Running on non-Fedora/RHEL, skip orig file preservation.")
} else {
return err
}
} else if !os.IsNotExist(err) {
return err
}
if _, err := os.Stat(fpath); os.IsNotExist(err) {

if !orig {
if _, err := os.Stat(noOrigFileStampName(fpath)); err == nil {
// we already created the no orig file for this default file
return nil
}

// check whether there is already an orig preservation for the path, and remove upon existence (wrongly preserved)
if _, err := os.Stat(origFileName(fpath)); err == nil {
if delErr := os.Remove(origFileName(fpath)); delErr != nil {
return fmt.Errorf("deleting orig file for %q: %w", origFileName(fpath), delErr)
}
klog.Infof("Removing files %q completely for incorrect preservation", origFileName(fpath))
}

// create a noorig file that tells the MCD that the file wasn't present on disk before MCD
// took over so it can just remove it when deleting stale data, as opposed as restoring a file
// that was shipped _with_ the underlying OS (e.g. a default chrony config).
Expand Down
28 changes: 18 additions & 10 deletions pkg/daemon/update.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1245,6 +1245,7 @@ func (dn *Daemon) isPathInDropins(path string, systemd *ign3types.Systemd) bool
//nolint:gocyclo
func (dn *Daemon) deleteStaleData(oldIgnConfig, newIgnConfig ign3types.Config) error {
klog.Info("Deleting stale data")

newFileSet := make(map[string]struct{})
for _, f := range newIgnConfig.Storage.Files {
newFileSet[f.Path] = struct{}{}
Expand Down Expand Up @@ -1282,20 +1283,27 @@ func (dn *Daemon) deleteStaleData(oldIgnConfig, newIgnConfig ign3types.Config) e
// Add a check for backwards compatibility: basically if the file doesn't exist in /usr/etc (on FCOS/RHCOS)
// and no rpm is claiming it, we assume that the orig file came from a wrongful backup of a MachineConfig
// file instead of a file originally on disk. See https://bugzilla.redhat.com/show_bug.cgi?id=1814397
var restore bool
if _, err := exec.Command("rpm", "-qf", f.Path).CombinedOutput(); err == nil {
restore := false
rpmNotFound, isOwned, err := isFileOwnedByRPMPkg(f.Path)
if isOwned {
// File is owned by an rpm
restore = true
} else if strings.HasPrefix(f.Path, "/etc") && dn.os.IsCoreOSVariant() {
if _, err := os.Stat(withUsrPath(f.Path)); err != nil {
if !os.IsNotExist(err) {
return err
} else if !isOwned && (err == nil) {
// Run on Fedora/RHEL - check whether the file exist in /usr/etc (on FCOS/RHCOS)
if strings.HasPrefix(f.Path, "/etc") {
if _, err := os.Stat(withUsrPath(f.Path)); err != nil {
if !os.IsNotExist(err) {
return err
}
} else {
restore = true
}

// If the error is ErrNotExist then we don't restore the file
} else {
restore = true
}
} else if rpmNotFound {
// Run on non-Fedora/RHEL machine
klog.Infof("Running on non-Fedora/RHEL machine, skip file restoration.")
} else {
return err
}

if restore {
Expand Down
43 changes: 6 additions & 37 deletions pkg/daemon/update_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -817,51 +817,20 @@ func TestOriginalFileBackupRestore(t *testing.T) {
testDir, cleanup := setupTempDirWithEtc(t)
defer cleanup()

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@cheesesashimi cheesesashimi Jul 27, 2023 •
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suggestion (non-blocking): Since the createOrigFile() function now has a implicit dependency on the rpm binary, this test will fail if the rpm binary is not present in environment where the test is running.

This is noteworthy for two reasons:

  1. If the rpm binary is not present and createOrigFile() is called, exec.Command() will return an error that indicates that the rpm binary is not found. However, the rest of the path in createOrigFile() will assume that it just means that the file is not owned by an RPM. We could add some explicit checking to the RPM command to alleviate that concern.
  2. If someone is running the test on a host without the RPM binary being present, the test will either pass due to the above behavior or it will fail.

There are two ways we can mitigate this:

  1. Check what OS the test is running on and skip the test if they're not running on a Linux host. You can do that like this:
if runtime.GOOS != "linux" {
	t.Skipf("detected OS: %s, skipping test", runtime.GOOS)
}
  1. Check whether their host has the rpm binary on it and skip the test if it is not found. You can do that like this:
// Check for an rpm binary in $PATH.
_, err := exec.LookPath("rpm")
if err != nil {
	t.Skip("rpm command not found")
}

Out of the two, I think I prefer approach 1 because if, say, our base image was to somehow be missing the rpm binary, the test will fail loudly and explicitly. Whereas with approach 2, if the binary is missing, it will be silently skipped which could make diagnosis much more difficult in the future.

// Write a normal file as a control to make sure normal case works
// Write a file in the /tmp dir to test whether orig files are selectively preserved
controlFile := filepath.Join(testDir, "control-file")
err := os.WriteFile(controlFile, []byte("control file contents"), 0755)
assert.Nil(t, err)

// Back up that normal file
// Back up the tmp file
err = createOrigFile(controlFile, controlFile)
assert.Nil(t, err)

// Now try again and make sure it knows it's already backed up
// Now try again and make sure it knows it's already backed up if it should be
err = createOrigFile(controlFile, controlFile)
assert.Nil(t, err)

// Restore the normal file
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question: Are these tests no longer needed or do they now fail with this new change?

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I think I am deleting those because they now fail with this new change. This is because the tests create files in the /tmp folder, try to create orig files for those and see if that is successful by restoring form the orig files. But the current workaround stops the orig file preservation for the files in the /tmp folder as they are not the original files shipped with the disk, so the tests are no longer valid. However, I have also tested the current createOrig' s functionality in preserving the files by putting a forceCreate variable in, so that when running the test, the origs are forcedly created for these /tmp files. After verifying its functionality, I removed those variables as well as the tests.

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To give a bit more context, I think these tests aren't really needed anymore since we are now (properly) not preserving anything written to /tmp, since they shouldn't have been preserved in the first place.

We could instead test preservation of /etc specifically but it is a bit harder to do so via a unit test and may modify the user's system, so we decided to remove this test for now. If there is a simple way to test that that we're missing, would also be happy to take suggestions!

err = restorePath(controlFile)
assert.Nil(t, err)

// The normal file worked, try it with a symlink
// Write a file we can point a symlink at
err = os.WriteFile(filepath.Join(testDir, "target-file"), []byte("target file contents"), 0755)
assert.Nil(t, err)

// Make a relative symlink
relativeSymlink := filepath.Join(testDir, "etc", "relative-symlink-to-target-file")
relativeSymlinkTarget := filepath.Join("..", "target-file")
err = os.Symlink(relativeSymlinkTarget, relativeSymlink)
assert.Nil(t, err)

// Back up the relative symlink
err = createOrigFile(relativeSymlink, relativeSymlink)
assert.Nil(t, err)

// Remove the symlink and write a file over it
fileOverSymlink := filepath.Join(testDir, "etc", "relative-symlink-to-target-file")
err = os.Remove(fileOverSymlink)
assert.Nil(t, err)
err = os.WriteFile(fileOverSymlink, []byte("replacement contents"), 0755)
assert.Nil(t, err)

// Try to back it up again make sure it knows it's already backed up
err = createOrigFile(relativeSymlink, relativeSymlink)
assert.Nil(t, err)

// Finally, make sure we can restore the relative symlink if we rollback
err = restorePath(relativeSymlink)
assert.Nil(t, err)

// Check whether there is an orig preservation for the path - OK: there is no back up for the tmp file
_, err = os.Stat(origFileName(controlFile))
assert.True(t, os.IsNotExist(err))
}