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>

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index d31b60f5d40d..f3309a7edb49 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -593,7 +593,7 @@ int
 	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 	if (ret)
 		return ret;
-	ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
+	ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
 	posix_acl_release(acl);
 	return ret;
 }
@@ -918,7 +918,7 @@ set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
 		if (ret)
 			return ret;
 	}
-	return inode->i_op->set_acl(inode, acl, type);
+	return inode->i_op->set_acl(mnt_userns, inode, acl, type);
 }
 EXPORT_SYMBOL(set_posix_acl);
 
@@ -966,12 +966,13 @@ const struct xattr_handler posix_acl_default_xattr_handler = {
 };
 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 
-int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+		   struct posix_acl *acl, int type)
 {
 	int error;
 
 	if (type == ACL_TYPE_ACCESS) {
-		error = posix_acl_update_mode(&init_user_ns, inode,
+		error = posix_acl_update_mode(mnt_userns, inode,
 				&inode->i_mode, &acl);
 		if (error)
 			return error;