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ovl: handle idmappings in layer open helpers 

In earlier patches we already passed down the relevant upper or lower
path to ovl_open_realfile(). Now let the open helpers actually take the
idmapping of the relevant mount into account when checking permissions.
This is needed to support idmapped base layers with overlay.

Cc: <linux-unionfs@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Christian Brauner 2022-04-04 12:51:56 +02:00 committed by Miklos Szeredi
parent 4b7791b2e9
commit 8423b3bd7d
2 changed files with 7 additions and 4 deletions
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6
fs/overlayfs/file.c
View File

@ -42,6 +42,7 @@ static struct file *ovl_open_realfile(const struct file *file,
{
struct inode *realinode = d_inode(realpath->dentry);
struct inode *inode = file_inode(file);
struct user_namespace *real_mnt_userns;
struct file *realfile;
const struct cred *old_cred;
int flags = file->f_flags | OVL_OPEN_FLAGS;
@ -52,11 +53,12 @@ static struct file *ovl_open_realfile(const struct file *file,
acc_mode |= MAY_APPEND;
old_cred = ovl_override_creds(inode->i_sb);
err = inode_permission(&init_user_ns, realinode, MAY_OPEN | acc_mode);
real_mnt_userns = mnt_user_ns(realpath->mnt);
err = inode_permission(real_mnt_userns, realinode, MAY_OPEN | acc_mode);
if (err) {
realfile = ERR_PTR(err);
} else {
if (!inode_owner_or_capable(&init_user_ns, realinode))
if (!inode_owner_or_capable(real_mnt_userns, realinode))
flags &= ~O_NOATIME;
realfile = open_with_fake_path(&file->f_path, flags, realinode,

5
fs/overlayfs/util.c
View File

@ -493,6 +493,7 @@ bool ovl_is_whiteout(struct dentry *dentry)
struct file *ovl_path_open(struct path *path, int flags)
{
struct inode *inode = d_inode(path->dentry);
struct user_namespace *real_mnt_userns = mnt_user_ns(path->mnt);
int err, acc_mode;
if (flags & ~(O_ACCMODE | O_LARGEFILE))
@ -509,12 +510,12 @@ struct file *ovl_path_open(struct path *path, int flags)
BUG();
}
err = inode_permission(&init_user_ns, inode, acc_mode | MAY_OPEN);
err = inode_permission(real_mnt_userns, inode, acc_mode | MAY_OPEN);
if (err)
return ERR_PTR(err);
/* O_NOATIME is an optimization, don't fail if not permitted */
if (inode_owner_or_capable(&init_user_ns, inode))
if (inode_owner_or_capable(real_mnt_userns, inode))
flags |= O_NOATIME;
return dentry_open(path, flags, current_cred());