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[release-1.39] chroot createPlatformContainer: use MS_REMOUNT #6003

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Merged
merged 1 commit into from
Feb 25, 2025
Merged

[release-1.39] chroot createPlatformContainer: use MS_REMOUNT #6003

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2 changes: 1 addition & 1 deletion chroot/run_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -263,7 +263,7 @@ func createPlatformContainer(options runUsingChrootExecSubprocOptions) error {
return fmt.Errorf("changing to host root directory: %w", err)
}
// make sure we only unmount things under this tree
if err := unix.Mount(".", ".", "bind", unix.MS_BIND|unix.MS_SLAVE|unix.MS_REC, ""); err != nil {
if err := unix.Mount(".", ".", "bind", unix.MS_REMOUNT|unix.MS_BIND|unix.MS_SLAVE|unix.MS_REC, ""); err != nil {
return fmt.Errorf("tweaking mount flags on host root directory before unmounting from mount namespace: %w", err)
}
// detach this (unnamed?) old directory
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20 changes: 20 additions & 0 deletions tests/run.bats
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Expand Up @@ -997,3 +997,23 @@ _EOF
run_buildah ? bud --pull=false --layers .
expect_output --substring -- "-c requires an argument"
}

@test "root fs only mounted once" {
if test `uname` != Linux ; then
skip "not meaningful except on Linux"
fi
_prefetch busybox
run_buildah from --pull=never --quiet busybox
cid="$output"
run_buildah run $cid cat /proc/self/mountinfo
echo "$output" > ${TEST_SCRATCH_DIR}/mountinfo1
echo "# mountinfo unfiltered:"
cat ${TEST_SCRATCH_DIR}/mountinfo1
grep ' / rw,' ${TEST_SCRATCH_DIR}/mountinfo1 > ${TEST_SCRATCH_DIR}/mountinfo2
echo "# mountinfo grepped:"
cat ${TEST_SCRATCH_DIR}/mountinfo2
wc -l < ${TEST_SCRATCH_DIR}/mountinfo2 > ${TEST_SCRATCH_DIR}/mountinfo3
echo "# mountinfo count:"
cat ${TEST_SCRATCH_DIR}/mountinfo3
assert $(cat ${TEST_SCRATCH_DIR}/mountinfo3) -eq 1
}