fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

3 files changed, 13 insertions, 9 deletions

diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
index 3bf2ae0e467c..527f6e46cbe8 100644
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -189,8 +189,8 @@ static int hfs_dir_release(struct inode *inode, struct file *file)
  * a directory and return a corresponding inode, given the inode for
  * the directory and the name (and its length) of the new file.
  */
-static int hfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-		      bool excl)
+static int hfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct inode *inode;
 	int res;
@@ -219,7 +219,8 @@ static int hfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  * in a directory, given the inode for the parent directory and the
  * name (and its length) of the new directory.
  */
-static int hfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int hfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		     struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
 	int res;
@@ -279,9 +280,9 @@ static int hfs_remove(struct inode *dir, struct dentry *dentry)
  * new file/directory.
  * XXX: how do you handle must_be dir?
  */
-static int hfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-		      struct inode *new_dir, struct dentry *new_dentry,
-		      unsigned int flags)
+static int hfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+		      struct dentry *old_dentry, struct inode *new_dir,
+		      struct dentry *new_dentry, unsigned int flags)
 {
 	int res;
 
diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h
index f71c384064c8..b8eb0322a3e5 100644
--- a/fs/hfs/hfs_fs.h
+++ b/fs/hfs/hfs_fs.h
@@ -204,7 +204,8 @@ extern const struct address_space_operations hfs_btree_aops;
 extern struct inode *hfs_new_inode(struct inode *, const struct qstr *, umode_t);
 extern void hfs_inode_write_fork(struct inode *, struct hfs_extent *, __be32 *, __be32 *);
 extern int hfs_write_inode(struct inode *, struct writeback_control *);
-extern int hfs_inode_setattr(struct dentry *, struct iattr *);
+extern int hfs_inode_setattr(struct user_namespace *, struct dentry *,
+			     struct iattr *);
 extern void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
 			__be32 log_size, __be32 phys_size, u32 clump_size);
 extern struct inode *hfs_iget(struct super_block *, struct hfs_cat_key *, hfs_cat_rec *);
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index c646218b72bf..3fc5cb346586 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -602,13 +602,15 @@ static int hfs_file_release(struct inode *inode, struct file *file)
  *     correspond to the same HFS file.
  */
 
-int hfs_inode_setattr(struct dentry *dentry, struct iattr * attr)
+int hfs_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		      struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct hfs_sb_info *hsb = HFS_SB(inode->i_sb);
 	int error;
 
-	error = setattr_prepare(&init_user_ns, dentry, attr); /* basic permission checks */
+	error = setattr_prepare(&init_user_ns, dentry,
+				attr); /* basic permission checks */
 	if (error)
 		return error;