From: Amir Goldstein <amir73il@gmail.com>
To: Zorro Lang <zlang@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Christian Brauner <brauner@kernel.org>,
Christoph Hellwig <hch@lst.de>,
linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
fstests@vger.kernel.org
Subject: [PATCH v2] src/vfs: skip whiteout-device fixtures on overlayfs
Date: Sat, 17 Oct 2026 11:22:29 +0200 [thread overview]
Message-ID: <20261017092229.2363746-1-amir73il@gmail.com> (raw)
From: Christian Brauner <brauner@kernel.org>
The idmapped mount tests create a whiteout device,
mknod(S_IFCHR, makedev(0, 0)), as a fixture: a whiteout device is the
only character device an unprivileged caller may create, since it is
exempt from the CAP_MKNOD check. overlayfs reserves a 0:0 character
device as its on-disk whiteout marker, so ovl_mknod() returns -EPERM
and the fixture cannot be created, failing generic/633, generic/696 and
generic/697 on overlayfs.
Add a whiteout_device_supported() helper and skip the whiteout-device
fixtures and the checks that depend on them on overlayfs. The
makedev(5, 1) "creation must fail" probes are unaffected and keep
running. No-op on every other filesystem.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
Changes since v1 [1]:
- Patch "probe O_TMPFILE support..." already merged
- Repalce is_overlayfs() probe with whiteout_device_supported()
[1] https://lore.kernel.org/linux-unionfs/20260615-overlay-idmapped-vfstest-v1-0-c6b3b2228092@kernel.org/
src/vfs/idmapped-mounts.c | 154 ++++++++++++++++++++------------------
src/vfs/utils.c | 25 +++++++
src/vfs/utils.h | 1 +
3 files changed, 107 insertions(+), 73 deletions(-)
diff --git a/src/vfs/idmapped-mounts.c b/src/vfs/idmapped-mounts.c
index 3e1b6987..1cca86dc 100644
--- a/src/vfs/idmapped-mounts.c
+++ b/src/vfs/idmapped-mounts.c
@@ -432,6 +432,7 @@ out:
int tcore_fsids_mapped(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, hardlink_target_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -534,7 +535,7 @@ int tcore_fsids_mapped(const struct vfstest_info *info)
die("failure: create");
/* create character device */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | 0644, makedev(0, 0)))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | 0644, makedev(0, 0)))
die("failure: create");
/* create symlink */
@@ -734,6 +735,7 @@ out:
/* Validate that changing file ownership works correctly on idmapped mounts. */
int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd1 = -EBADF, open_tree_fd2 = -EBADF;
struct mount_attr attr1 = {
@@ -763,7 +765,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
}
/* create character device */
- if (mknodat(info->t_dir1_fd, CHRDEV1, S_IFCHR | 0644, makedev(0, 0))) {
+ if (whiteout_dev && mknodat(info->t_dir1_fd, CHRDEV1, S_IFCHR | 0644, makedev(0, 0))) {
log_stderr("failure: mknodat");
goto out;
}
@@ -824,7 +826,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 0, 0)) {
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 0, 0)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -856,7 +858,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 10000, 10000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 10000, 10000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -911,7 +913,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 30000, 30000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 30000, 30000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -941,7 +943,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: fchownat");
goto out;
}
- if (fchownat(info->t_dir1_fd, CHRDEV1, 2000, 2000, 0)) {
+ if (whiteout_dev && fchownat(info->t_dir1_fd, CHRDEV1, 2000, 2000, 0)) {
log_stderr("failure: fchownat");
goto out;
}
@@ -971,7 +973,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 2000, 2000)) {
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 2000, 2000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1001,7 +1003,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 12000, 12000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 12000, 12000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1031,7 +1033,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 32000, 32000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 32000, 32000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1063,7 +1065,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (!fchownat(info->t_dir1_fd, HARDLINK1, 1000, 1000, 0))
die("failure: fchownat");
- if (!fchownat(info->t_dir1_fd, CHRDEV1, 1000, 1000, 0))
+ if (whiteout_dev && !fchownat(info->t_dir1_fd, CHRDEV1, 1000, 1000, 0))
die("failure: fchownat");
if (!fchownat(info->t_dir1_fd, SYMLINK1, 2000, 2000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1078,7 +1080,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (!fchownat(open_tree_fd2, HARDLINK1, 1000, 1000, 0))
die("failure: fchownat");
- if (!fchownat(open_tree_fd2, CHRDEV1, 1000, 1000, 0))
+ if (whiteout_dev && !fchownat(open_tree_fd2, CHRDEV1, 1000, 1000, 0))
die("failure: fchownat");
if (!fchownat(open_tree_fd2, SYMLINK1, 2000, 2000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1093,7 +1095,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (fchownat(open_tree_fd1, HARDLINK1, 1000, 1000, 0))
die("failure: fchownat");
- if (fchownat(open_tree_fd1, CHRDEV1, 1000, 1000, 0))
+ if (whiteout_dev && fchownat(open_tree_fd1, CHRDEV1, 1000, 1000, 0))
die("failure: fchownat");
if (fchownat(open_tree_fd1, SYMLINK1, 2000, 2000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1108,7 +1110,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(info->t_dir1_fd, HARDLINK1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
if (!expected_uid_gid(info->t_dir1_fd, SYMLINK1, AT_SYMLINK_NOFOLLOW, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
@@ -1123,7 +1125,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd2, HARDLINK1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd2, SYMLINK1, AT_SYMLINK_NOFOLLOW, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
@@ -1138,7 +1140,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd1, HARDLINK1, 0, 1000, 1000))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 1000, 1000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 1000, 1000))
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd1, SYMLINK1, AT_SYMLINK_NOFOLLOW, 2000, 2000))
die("failure: expected_uid_gid");
@@ -1166,7 +1168,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 1000, 1000)) {
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 1000, 1000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1196,7 +1198,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 11000, 11000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 11000, 11000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1226,7 +1228,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 31000, 31000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 31000, 31000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1258,7 +1260,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (!fchownat(info->t_dir1_fd, HARDLINK1, 0, 0, 0))
die("failure: fchownat");
- if (!fchownat(info->t_dir1_fd, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && !fchownat(info->t_dir1_fd, CHRDEV1, 0, 0, 0))
die("failure: fchownat");
if (!fchownat(info->t_dir1_fd, SYMLINK1, 3000, 3000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1273,7 +1275,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (!fchownat(open_tree_fd1, HARDLINK1, 0, 0, 0))
die("failure: fchownat");
- if (!fchownat(open_tree_fd1, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && !fchownat(open_tree_fd1, CHRDEV1, 0, 0, 0))
die("failure: fchownat");
if (!fchownat(open_tree_fd1, SYMLINK1, 3000, 3000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1288,7 +1290,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: fchownat");
if (fchownat(open_tree_fd2, HARDLINK1, 0, 0, 0))
die("failure: fchownat");
- if (fchownat(open_tree_fd2, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && fchownat(open_tree_fd2, CHRDEV1, 0, 0, 0))
die("failure: fchownat");
if (!fchownat(open_tree_fd2, SYMLINK1, 3000, 3000, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW))
die("failure: fchownat");
@@ -1303,7 +1305,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(info->t_dir1_fd, HARDLINK1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
if (!expected_uid_gid(info->t_dir1_fd, SYMLINK1, AT_SYMLINK_NOFOLLOW, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
@@ -1318,7 +1320,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd1, HARDLINK1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd1, SYMLINK1, AT_SYMLINK_NOFOLLOW, info->t_overflowuid, info->t_overflowgid))
die("failure: expected_uid_gid");
@@ -1333,7 +1335,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd2, HARDLINK1, 0, 0, 0))
die("failure: expected_uid_gid");
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 0, 0))
die("failure: expected_uid_gid");
if (!expected_uid_gid(open_tree_fd2, SYMLINK1, AT_SYMLINK_NOFOLLOW, 2000, 2000))
die("failure: expected_uid_gid");
@@ -1361,7 +1363,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 0, 0)) {
+ if (whiteout_dev && !expected_uid_gid(info->t_dir1_fd, CHRDEV1, 0, 0, 0)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1391,7 +1393,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 10000, 10000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd1, CHRDEV1, 0, 10000, 10000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -1421,7 +1423,7 @@ int tcore_expected_uid_gid_idmapped_mounts(const struct vfstest_info *info)
log_stderr("failure: expected_uid_gid");
goto out;
}
- if (!expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 30000, 30000)) {
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd2, CHRDEV1, 0, 30000, 30000)) {
log_stderr("failure: expected_uid_gid");
goto out;
}
@@ -3781,6 +3783,7 @@ out:
int tcore_setgid_create_idmapped(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -3881,10 +3884,10 @@ int tcore_setgid_create_idmapped(const struct vfstest_info *info)
die("failure: is_setgid");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
/*
@@ -3906,7 +3909,7 @@ int tcore_setgid_create_idmapped(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 10000, 10000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -3918,7 +3921,7 @@ int tcore_setgid_create_idmapped(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -3957,6 +3960,7 @@ out:
int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -4051,10 +4055,10 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
die("failure: is_setgid");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (!is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && !is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0))
@@ -4066,7 +4070,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 0))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -4078,7 +4082,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -4168,10 +4172,10 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
die("failure: is_setgid");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
/*
@@ -4193,7 +4197,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 1000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -4205,7 +4209,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -4293,10 +4297,10 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
die("failure: is_setgid");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0))
@@ -4308,7 +4312,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 0))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 0))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -4320,7 +4324,7 @@ int tcore_setgid_create_idmapped_in_userns(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -7675,6 +7679,7 @@ out:
*/
static int setgid_create_umask_idmapped(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -7793,13 +7798,13 @@ static int setgid_create_umask_idmapped(const struct vfstest_info *info)
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -7821,7 +7826,7 @@ static int setgid_create_umask_idmapped(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 10000, 10000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -7833,7 +7838,7 @@ static int setgid_create_umask_idmapped(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -7889,6 +7894,7 @@ out:
*/
static int setgid_create_umask_idmapped_in_userns(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -8028,13 +8034,13 @@ static int setgid_create_umask_idmapped_in_userns(const struct vfstest_info *inf
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -8056,7 +8062,7 @@ static int setgid_create_umask_idmapped_in_userns(const struct vfstest_info *inf
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 1000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -8068,7 +8074,7 @@ static int setgid_create_umask_idmapped_in_userns(const struct vfstest_info *inf
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -8123,6 +8129,7 @@ out:
*/
static int setgid_create_acl_idmapped(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -8248,13 +8255,13 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -8276,7 +8283,7 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 10000, 10000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -8288,7 +8295,7 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -8383,13 +8390,13 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (!is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && !is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -8411,7 +8418,7 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 10000, 10000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 10000, 10000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -8423,7 +8430,7 @@ static int setgid_create_acl_idmapped(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -8478,6 +8485,7 @@ out:
*/
static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
{
+ bool whiteout_dev = whiteout_device_supported(info->t_dir1_fd);
int fret = -1;
int file1_fd = -EBADF, open_tree_fd = -EBADF;
struct mount_attr attr = {
@@ -8624,13 +8632,13 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -8652,7 +8660,7 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 1000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -8664,7 +8672,7 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
@@ -8766,13 +8774,13 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
if (!is_ixgrp(open_tree_fd, FILE2, 0))
die("failure: is_ixgrp");
/* create a whiteout device via mknodat() vfs_mknod */
- if (mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
+ if (whiteout_dev && mknodat(open_tree_fd, CHRDEV1, S_IFCHR | S_ISGID | S_IXGRP, 0))
die("failure: mknodat");
- if (is_setgid(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && is_setgid(open_tree_fd, CHRDEV1, 0))
die("failure: is_setgid");
- if (!is_ixgrp(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && !is_ixgrp(open_tree_fd, CHRDEV1, 0))
die("failure: is_ixgrp");
/*
@@ -8794,7 +8802,7 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
if (!expected_uid_gid(open_tree_fd, FILE2, 0, 0, 1000))
die("failure: check ownership");
- if (!expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
+ if (whiteout_dev && !expected_uid_gid(open_tree_fd, CHRDEV1, 0, 0, 1000))
die("failure: check ownership");
if (unlinkat(open_tree_fd, FILE1, 0))
@@ -8806,7 +8814,7 @@ static int setgid_create_acl_idmapped_in_userns(const struct vfstest_info *info)
if (unlinkat(open_tree_fd, FILE2, 0))
die("failure: delete");
- if (unlinkat(open_tree_fd, CHRDEV1, 0))
+ if (whiteout_dev && unlinkat(open_tree_fd, CHRDEV1, 0))
die("failure: delete");
/* create tmpfile via filesystem tmpfile api */
diff --git a/src/vfs/utils.c b/src/vfs/utils.c
index 0b435afe..0094adc3 100644
--- a/src/vfs/utils.c
+++ b/src/vfs/utils.c
@@ -955,6 +955,31 @@ bool openat_tmpfile_supported(int dirfd)
return true;
}
+/*
+ * A 0:0 character device is the only device node an unprivileged caller may
+ * create, so the idmapped mount tests use one as a fixture. overlayfs reserves
+ * that dev_t as its whiteout marker and ovl_mknod() rejects it with EPERM.
+ * Probe on the base mount as the filesystem owner so a filesystem that later
+ * allows the node keeps the coverage. Any error other than EPERM is reported.
+ */
+bool whiteout_device_supported(int dirfd)
+{
+ static const char name[] = ".whiteout_probe";
+
+ if (!mknodat(dirfd, name, S_IFCHR | 0644, makedev(0, 0))) {
+ if (unlinkat(dirfd, name, 0))
+ return log_errno(false, "failure: unlinkat");
+ return true;
+ }
+
+ if (errno == EPERM) {
+ errno = 0;
+ return false;
+ }
+
+ return log_errno(false, "failure: mknodat");
+}
+
/*
* There'll be scenarios where you'll want to see the attributes associated with
* a directory tree during debugging or just to make sure things look correct.
diff --git a/src/vfs/utils.h b/src/vfs/utils.h
index c086885a..41b2f499 100644
--- a/src/vfs/utils.h
+++ b/src/vfs/utils.h
@@ -372,5 +372,6 @@ extern bool is_setgid(int dfd, const char *path, int flags);
extern bool is_sticky(int dfd, const char *path, int flags);
extern bool is_ixgrp(int dfd, const char *path, int flags);
extern bool openat_tmpfile_supported(int dirfd);
+extern bool whiteout_device_supported(int dirfd);
#endif /* __IDMAP_UTILS_H */
--
2.55.0
next reply other threads:[~2026-10-17 9:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 9:22 Amir Goldstein [this message]
-- strict thread matches above, loose matches on Subject: below --
2026-10-17 9:28 [PATCH v2] src/vfs: skip whiteout-device fixtures on overlayfs Amir Goldstein
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