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>

5 files changed, 25 insertions, 15 deletions

diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
index 9031f7df2d48..b9a9db98e94b 100644
--- a/fs/ext2/acl.c
+++ b/fs/ext2/acl.c
@@ -216,7 +216,8 @@ __ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  * inode->i_mutex: down
  */
 int
-ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+ext2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+	     struct posix_acl *acl, int type)
 {
 	int error;
 	int update_mode = 0;
diff --git a/fs/ext2/acl.h b/fs/ext2/acl.h
index 0f01c759daac..917db5f6630a 100644
--- a/fs/ext2/acl.h
+++ b/fs/ext2/acl.h
@@ -56,7 +56,8 @@ static inline int ext2_acl_count(size_t size)
 
 /* acl.c */
 extern struct posix_acl *ext2_get_acl(struct inode *inode, int type);
-extern int ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type);
+extern int ext2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+			struct posix_acl *acl, int type);
 extern int ext2_init_acl (struct inode *, struct inode *);
 
 #else
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 2a4175fbaf5e..3309fb2d327a 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -764,8 +764,9 @@ extern struct inode *ext2_iget (struct super_block *, unsigned long);
 extern int ext2_write_inode (struct inode *, struct writeback_control *);
 extern void ext2_evict_inode(struct inode *);
 extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
-extern int ext2_setattr (struct dentry *, struct iattr *);
-extern int ext2_getattr (const struct path *, struct kstat *, u32, unsigned int);
+extern int ext2_setattr (struct user_namespace *, struct dentry *, struct iattr *);
+extern int ext2_getattr (struct user_namespace *, const struct path *,
+			 struct kstat *, u32, unsigned int);
 extern void ext2_set_inode_flags(struct inode *inode);
 extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		       u64 start, u64 len);
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 3d8acafca8ce..68178b2234bd 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1638,8 +1638,8 @@ int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
 	return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 }
 
-int ext2_getattr(const struct path *path, struct kstat *stat,
-		u32 request_mask, unsigned int query_flags)
+int ext2_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 ext2_inode_info *ei = EXT2_I(inode);
@@ -1664,7 +1664,8 @@ int ext2_getattr(const struct path *path, struct kstat *stat,
 	return 0;
 }
 
-int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
+int ext2_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		 struct iattr *iattr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index ea980f1e2e99..3367384d344d 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -100,7 +100,9 @@ struct dentry *ext2_get_parent(struct dentry *child)
  * If the create succeeds, we fill in the inode information
  * with d_instantiate(). 
  */
-static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
+static int ext2_create (struct user_namespace * mnt_userns,
+			struct inode * dir, struct dentry * dentry,
+			umode_t mode, bool excl)
 {
 	struct inode *inode;
 	int err;
@@ -118,7 +120,8 @@ static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode
 	return ext2_add_nondir(dentry, inode);
 }
 
-static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int ext2_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode = ext2_new_inode(dir, mode, NULL);
 	if (IS_ERR(inode))
@@ -131,7 +134,8 @@ static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 	return 0;
 }
 
-static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
+static int ext2_mknod (struct user_namespace * mnt_userns, struct inode * dir,
+	struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct inode * inode;
 	int err;
@@ -151,8 +155,8 @@ static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode,
 	return err;
 }
 
-static int ext2_symlink (struct inode * dir, struct dentry * dentry,
-	const char * symname)
+static int ext2_symlink (struct user_namespace * mnt_userns, struct inode * dir,
+	struct dentry * dentry, const char * symname)
 {
 	struct super_block * sb = dir->i_sb;
 	int err = -ENAMETOOLONG;
@@ -225,7 +229,8 @@ static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 	return err;
 }
 
-static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
+static int ext2_mkdir(struct user_namespace * mnt_userns,
+	struct inode * dir, struct dentry * dentry, umode_t mode)
 {
 	struct inode * inode;
 	int err;
@@ -315,8 +320,9 @@ static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
 	return err;
 }
 
-static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
-			struct inode * new_dir,	struct dentry * new_dentry,
+static int ext2_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)
 {
 	struct inode * old_inode = d_inode(old_dentry);