From: Amir Goldstein <amir73il@xxxxxxxxx>
Ensure that ovl_open_realfile() takes the mount's idmapping into
account. We add a new helper ovl_path_realdata() that can be used to
easily retrieve the relevant path which we can pass down. This is needed
to support idmapped base layers with overlay.
Cc: <linux-unionfs@xxxxxxxxxxxxxxx>
Tested-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
Reviewed-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/file.c | 22 +++++++++++++---------
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/util.c | 14 ++++++++++++++
3 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index fa125feed0ff..9250e04e97af 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -38,8 +38,9 @@ static char ovl_whatisit(struct inode *inode, struct inode *realinode)
#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
static struct file *ovl_open_realfile(const struct file *file,
- struct inode *realinode)
+ struct path *realpath)
{
+ struct inode *realinode = d_inode(realpath->dentry);
struct inode *inode = file_inode(file);
struct file *realfile;
const struct cred *old_cred;
@@ -104,21 +105,21 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
bool allow_meta)
{
- struct inode *inode = file_inode(file);
- struct inode *realinode;
+ struct dentry *dentry = file_dentry(file);
+ struct path realpath;
real->flags = 0;
real->file = file->private_data;
if (allow_meta)
- realinode = ovl_inode_real(inode);
+ ovl_path_real(dentry, &realpath);
else
- realinode = ovl_inode_realdata(inode);
+ ovl_path_realdata(dentry, &realpath);
/* Has it been copied up since we'd opened it? */
- if (unlikely(file_inode(real->file) != realinode)) {
+ if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
real->flags = FDPUT_FPUT;
- real->file = ovl_open_realfile(file, realinode);
+ real->file = ovl_open_realfile(file, &realpath);
return PTR_ERR_OR_ZERO(real->file);
}
@@ -144,17 +145,20 @@ static int ovl_real_fdget(const struct file *file, struct fd *real)
static int ovl_open(struct inode *inode, struct file *file)
{
+ struct dentry *dentry = file_dentry(file);
struct file *realfile;
+ struct path realpath;
int err;
- err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
+ err = ovl_maybe_copy_up(dentry, file->f_flags);
if (err)
return err;
/* No longer need these flags, so don't pass them on to underlying fs */
file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
- realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
+ ovl_path_realdata(dentry, &realpath);
+ realfile = ovl_open_realfile(file, &realpath);
if (IS_ERR(realfile))
return PTR_ERR(realfile);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index b003652f8827..816a69b46b67 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -319,6 +319,7 @@ void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct dentry *dentry, struct path *path);
void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
+enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 5a7e5d1e884b..42293610f64e 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -194,6 +194,20 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
return type;
}
+enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
+{
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ WARN_ON_ONCE(d_is_dir(dentry));
+
+ if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
+ ovl_path_lowerdata(dentry, path);
+ else
+ ovl_path_upper(dentry, path);
+
+ return type;
+}
+
struct dentry *ovl_dentry_upper(struct dentry *dentry)
{
return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
--
2.32.0
