fs: port ->permission() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

2 files changed, 8 insertions, 8 deletions

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 8c52b6c9d31a..73c1bbdc99c3 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -40,7 +40,7 @@ static int nfsd_acceptable(void *expv, struct dentry *dentry)
 		/* make sure parents give x permission to user */
 		int err;
 		parent = dget_parent(tdentry);
-		err = inode_permission(&init_user_ns,
+		err = inode_permission(&nop_mnt_idmap,
 				       d_inode(parent), MAY_EXEC);
 		if (err < 0) {
 			dput(parent);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 66517ad6ac13..ab4ee3509ce3 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -583,7 +583,7 @@ int nfsd4_is_junction(struct dentry *dentry)
 		return 0;
 	if (!(inode->i_mode & S_ISVTX))
 		return 0;
-	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
+	if (vfs_getxattr(&nop_mnt_idmap, dentry, NFSD_JUNCTION_XATTR_NAME,
 			 NULL, 0) <= 0)
 		return 0;
 	return 1;
@@ -2130,7 +2130,7 @@ nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
 
 	inode_lock_shared(inode);
 
-	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
+	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, NULL, 0);
 
 	/*
 	 * Zero-length attribute, just return.
@@ -2157,7 +2157,7 @@ nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
 		goto out;
 	}
 
-	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
+	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, buf, len);
 	if (len <= 0) {
 		kvfree(buf);
 		buf = NULL;
@@ -2268,7 +2268,7 @@ nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
 	inode_lock(fhp->fh_dentry->d_inode);
 	fh_fill_pre_attrs(fhp);
 
-	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
+	ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
 				       name, NULL);
 
 	fh_fill_post_attrs(fhp);
@@ -2295,7 +2295,7 @@ nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
 	inode_lock(fhp->fh_dentry->d_inode);
 	fh_fill_pre_attrs(fhp);
 
-	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
+	ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry, name, buf,
 				    len, flags, NULL);
 	fh_fill_post_attrs(fhp);
 	inode_unlock(fhp->fh_dentry->d_inode);
@@ -2379,14 +2379,14 @@ nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
 		return 0;
 
 	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
-	err = inode_permission(&init_user_ns, inode,
+	err = inode_permission(&nop_mnt_idmap, inode,
 			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
 
 	/* Allow read access to binaries even when mode 111 */
 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
 	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
 	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
-		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
+		err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
 
 	return err? nfserrno(err) : 0;
 }