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, 20 insertions, 15 deletions

diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index 29a9dcfbe81f..03e6c046faf4 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -434,8 +434,8 @@ out:
 	return res;
 }
 
-static int hfsplus_symlink(struct inode *dir, struct dentry *dentry,
-			   const char *symname)
+static int hfsplus_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			   struct dentry *dentry, const char *symname)
 {
 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
 	struct inode *inode;
@@ -476,8 +476,8 @@ out:
 	return res;
 }
 
-static int hfsplus_mknod(struct inode *dir, struct dentry *dentry,
-			 umode_t mode, dev_t rdev)
+static int hfsplus_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
 	struct inode *inode;
@@ -517,18 +517,20 @@ out:
 	return res;
 }
 
-static int hfsplus_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-			  bool excl)
+static int hfsplus_create(struct user_namespace *mnt_userns, struct inode *dir,
+			  struct dentry *dentry, umode_t mode, bool excl)
 {
-	return hfsplus_mknod(dir, dentry, mode, 0);
+	return hfsplus_mknod(&init_user_ns, dir, dentry, mode, 0);
 }
 
-static int hfsplus_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int hfsplus_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, umode_t mode)
 {
-	return hfsplus_mknod(dir, dentry, mode | S_IFDIR, 0);
+	return hfsplus_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0);
 }
 
-static int hfsplus_rename(struct inode *old_dir, struct dentry *old_dentry,
+static int hfsplus_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)
 {
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index a92de5199ec3..12b20479ed2b 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -488,8 +488,9 @@ void hfsplus_inode_write_fork(struct inode *inode,
 			      struct hfsplus_fork_raw *fork);
 int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd);
 int hfsplus_cat_write_inode(struct inode *inode);
-int hfsplus_getattr(const struct path *path, struct kstat *stat,
-		    u32 request_mask, unsigned int query_flags);
+int hfsplus_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		    struct kstat *stat, u32 request_mask,
+		    unsigned int query_flags);
 int hfsplus_file_fsync(struct file *file, loff_t start, loff_t end,
 		       int datasync);
 
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index 642e067d8fe8..7a937de9b2ad 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -241,7 +241,8 @@ static int hfsplus_file_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int hfsplus_setattr(struct dentry *dentry, struct iattr *attr)
+static int hfsplus_setattr(struct user_namespace *mnt_userns,
+			   struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
@@ -270,8 +271,9 @@ static int hfsplus_setattr(struct dentry *dentry, struct iattr *attr)
 	return 0;
 }
 
-int hfsplus_getattr(const struct path *path, struct kstat *stat,
-		    u32 request_mask, unsigned int query_flags)
+int hfsplus_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		    struct kstat *stat, u32 request_mask,
+		    unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
 	struct hfsplus_inode_info *hip = HFSPLUS_I(inode);