containerd/mount/mount_unix.go
Marat Radchenko d94a789d15 Fix usages of mountinfo.PrefixFilter
It says: The prefix path **must be absolute, have all symlinks resolved, and cleaned**. But those requirements are violated in lots of places.

What happens when it is given a non-canonicalized path is that `mountinfo.GetMounts` will not find mounts.

The trivial case is:
```
$ mkdir a && ln -s a b && mkdir b/c b/d && mount --bind b/c b/d && cat /proc/mounts | grep -- '[ab]/d'
/dev/sdd3 /home/user/a/d ext4 rw,noatime,discard 0 0
```
We asked to bind-mount b/c to b/d, but ended up with mount in a/d.
So, mount table always contains canonicalized mount points, and it is an error to look for non-canonicalized paths in it.

Signed-off-by: Marat Radchenko <marat@slonopotamus.org>
2023-09-10 15:14:26 +03:00

68 lines
1.5 KiB
Go

//go:build !windows && !darwin && !openbsd
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package mount
import (
"sort"
"github.com/moby/sys/mountinfo"
)
// UnmountRecursive unmounts the target and all mounts underneath, starting
// with the deepest mount first.
func UnmountRecursive(target string, flags int) error {
if target == "" {
return nil
}
target, err := CanonicalizePath(target)
if err != nil {
return err
}
mounts, err := mountinfo.GetMounts(mountinfo.PrefixFilter(target))
if err != nil {
return err
}
targetSet := make(map[string]struct{})
for _, m := range mounts {
targetSet[m.Mountpoint] = struct{}{}
}
var targets []string
for m := range targetSet {
targets = append(targets, m)
}
// Make the deepest mount be first
sort.SliceStable(targets, func(i, j int) bool {
return len(targets[i]) > len(targets[j])
})
for i, target := range targets {
if err := UnmountAll(target, flags); err != nil {
if i == len(targets)-1 { // last mount
return err
}
}
}
return nil
}