From 037ff315e608fe6da80a570b2d7e11444c3d28b8 Mon Sep 17 00:00:00 2001
From: Matt Heon <mheon@redhat.com>
Date: Tue, 19 May 2026 18:00:36 +0800
Subject: [PATCH] Use securejoin.SecureJoin when forming userns paths
.../github.com/containers/storage/userns.go | 92 +++++++++++++------
.../containers/storage/userns_unsupported.go | 14 +++
2 files changed, 79 insertions(+), 27 deletions(-)
create mode 100644 vendor/github.com/containers/storage/userns_unsupported.go
@@ -1,18 +1,21 @@
+//go:build linux
+
package storage
import (
"fmt"
"os"
"os/user"
- "path/filepath"
"strconv"
drivers "github.com/containers/storage/drivers"
"github.com/containers/storage/pkg/idtools"
"github.com/containers/storage/pkg/unshare"
"github.com/containers/storage/types"
+ securejoin "github.com/cyphar/filepath-securejoin"
libcontainerUser "github.com/opencontainers/runc/libcontainer/user"
"github.com/sirupsen/logrus"
+ "golang.org/x/sys/unix"
)
// getAdditionalSubIDs looks up the additional IDs configured for
@@ -85,40 +88,59 @@ const nobodyUser = 65534
// parseMountedFiles returns the maximum UID and GID found in the /etc/passwd and
// /etc/group files.
func parseMountedFiles(containerMount, passwdFile, groupFile string) uint32 {
+ var (
+ passwd *os.File
+ group *os.File
+ size int
+ err error
+ )
if passwdFile == "" {
- passwdFile = filepath.Join(containerMount, "etc/passwd")
- }
- if groupFile == "" {
- groupFile = filepath.Join(groupFile, "etc/group")
+ passwd, err = secureOpen(containerMount, "/etc/passwd")
+ } else {
+ // User-specified override from a volume. Will not be in
+ // container root.
+ passwd, err = os.Open(passwdFile)
}
-
- size := 0
-
- users, err := libcontainerUser.ParsePasswdFile(passwdFile)
if err == nil {
- for _, u := range users {
- // Skip the "nobody" user otherwise we end up with 65536
- // ids with most images
- if u.Name == "nobody" {
- continue
- }
- if u.Uid > size && u.Uid != nobodyUser {
- size = u.Uid
- }
- if u.Gid > size && u.Gid != nobodyUser {
- size = u.Gid
+ defer passwd.Close()
+
+ users, err := libcontainerUser.ParsePasswd(passwd)
+ if err == nil {
+ for _, u := range users {
+ // Skip the "nobody" user otherwise we end up with 65536
+ // ids with most images
+ if u.Name == "nobody" || u.Name == "nogroup" {
+ continue
+ }
+ if u.Uid > size && u.Uid != nobodyUser {
+ size = u.Uid + 1
+ }
+ if u.Gid > size && u.Gid != nobodyUser {
+ size = u.Gid + 1
+ }
}
}
}
- groups, err := libcontainerUser.ParseGroupFile(groupFile)
+ if groupFile == "" {
+ group, err = secureOpen(containerMount, "/etc/group")
+ } else {
+ // User-specified override from a volume. Will not be in
+ // container root.
+ group, err = os.Open(groupFile)
+ }
if err == nil {
- for _, g := range groups {
- if g.Name == "nobody" {
- continue
- }
- if g.Gid > size && g.Gid != nobodyUser {
- size = g.Gid
+ defer group.Close()
+
+ groups, err := libcontainerUser.ParseGroup(group)
+ if err == nil {
+ for _, g := range groups {
+ if g.Name == "nobody" || g.Name == "nogroup" {
+ continue
+ }
+ if g.Gid > size && g.Gid != nobodyUser {
+ size = g.Gid + 1
+ }
}
}
}
@@ -309,3 +331,19 @@ func getAutoUserNSIDMappings(
gidMap := append(availableGIDs.zip(requestedContainerGIDs), additionalGIDMappings...)
return uidMap, gidMap, nil
}
+
+// Securely open (read-only) a file in a container mount.
+func secureOpen(containerMount, file string) (*os.File, error) {
+ filePath, err := securejoin.SecureJoin(containerMount, file)
+ if err != nil {
+ return nil, err
+ }
+
+ flags := unix.O_PATH | unix.O_CLOEXEC | unix.O_RDONLY
+ fileHandle, err := os.OpenFile(filePath, flags, 0)
+ if err != nil {
+ return nil, err
+ }
+
+ return fileHandle, nil
+}
\ No newline at end of file
new file mode 100644
@@ -0,0 +1,14 @@
+//go:build !linux
+
+package storage
+
+import (
+ "errors"
+
+ "github.com/containers/storage/pkg/idtools"
+ "github.com/containers/storage/types"
+)
+
+func (s *store) getAutoUserNS(_ *types.AutoUserNsOptions, _ *Image, _ rwLayerStore, _ []roLayerStore) ([]idtools.IDMap, []idtools.IDMap, error) {
+ return nil, nil, errors.New("user namespaces are not supported on this platform")
+}
\ No newline at end of file
--
2.43.0