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, 26 insertions, 16 deletions

diff --git a/fs/affs/affs.h b/fs/affs/affs.h
index a755bef7c4c7..bfa89e131ead 100644
--- a/fs/affs/affs.h
+++ b/fs/affs/affs.h
@@ -167,27 +167,33 @@ extern const struct export_operations affs_export_ops;
 extern int	affs_hash_name(struct super_block *sb, const u8 *name, unsigned int len);
 extern struct dentry *affs_lookup(struct inode *dir, struct dentry *dentry, unsigned int);
 extern int	affs_unlink(struct inode *dir, struct dentry *dentry);
-extern int	affs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool);
-extern int	affs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
+extern int	affs_create(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool);
+extern int	affs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode);
 extern int	affs_rmdir(struct inode *dir, struct dentry *dentry);
 extern int	affs_link(struct dentry *olddentry, struct inode *dir,
 			  struct dentry *dentry);
-extern int	affs_symlink(struct inode *dir, struct dentry *dentry,
-			     const char *symname);
-extern int	affs_rename2(struct inode *old_dir, struct dentry *old_dentry,
-			    struct inode *new_dir, struct dentry *new_dentry,
-			    unsigned int flags);
+extern int	affs_symlink(struct user_namespace *mnt_userns,
+			struct inode *dir, struct dentry *dentry,
+			const char *symname);
+extern int	affs_rename2(struct user_namespace *mnt_userns,
+			struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry,
+			unsigned int flags);
 
 /* inode.c */
 
 extern struct inode		*affs_new_inode(struct inode *dir);
-extern int			 affs_notify_change(struct dentry *dentry, struct iattr *attr);
+extern int			 affs_notify_change(struct user_namespace *mnt_userns,
+					struct dentry *dentry, struct iattr *attr);
 extern void			 affs_evict_inode(struct inode *inode);
 extern struct inode		*affs_iget(struct super_block *sb,
 					unsigned long ino);
 extern int			 affs_write_inode(struct inode *inode,
 					struct writeback_control *wbc);
-extern int			 affs_add_entry(struct inode *dir, struct inode *inode, struct dentry *dentry, s32 type);
+extern int			 affs_add_entry(struct inode *dir, struct inode *inode,
+					struct dentry *dentry, s32 type);
 
 /* file.c */
 
diff --git a/fs/affs/inode.c b/fs/affs/inode.c
index 767e5bdfb703..2352a75bd9d6 100644
--- a/fs/affs/inode.c
+++ b/fs/affs/inode.c
@@ -216,7 +216,8 @@ affs_write_inode(struct inode *inode, struct writeback_control *wbc)
 }
 
 int
-affs_notify_change(struct dentry *dentry, struct iattr *attr)
+affs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
+		   struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
diff --git a/fs/affs/namei.c b/fs/affs/namei.c
index 41c5749f4db7..9ad22befce28 100644
--- a/fs/affs/namei.c
+++ b/fs/affs/namei.c
@@ -242,7 +242,8 @@ affs_unlink(struct inode *dir, struct dentry *dentry)
 }
 
 int
-affs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
+affs_create(struct user_namespace *mnt_userns, struct inode *dir,
+	    struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct super_block *sb = dir->i_sb;
 	struct inode	*inode;
@@ -273,7 +274,8 @@ affs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
 }
 
 int
-affs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+affs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+	   struct dentry *dentry, umode_t mode)
 {
 	struct inode		*inode;
 	int			 error;
@@ -311,7 +313,8 @@ affs_rmdir(struct inode *dir, struct dentry *dentry)
 }
 
 int
-affs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+affs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+	     struct dentry *dentry, const char *symname)
 {
 	struct super_block	*sb = dir->i_sb;
 	struct buffer_head	*bh;
@@ -498,9 +501,9 @@ done:
 	return retval;
 }
 
-int affs_rename2(struct inode *old_dir, struct dentry *old_dentry,
-			struct inode *new_dir, struct dentry *new_dentry,
-			unsigned int flags)
+int affs_rename2(struct user_namespace *mnt_userns, struct inode *old_dir,
+		 struct dentry *old_dentry, struct inode *new_dir,
+		 struct dentry *new_dentry, unsigned int flags)
 {
 
 	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))