From 116e5258e4115aca0c64ac0bf40ded3b353ed626 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Thu, 22 Feb 2018 10:39:52 +0100
Subject: [PATCH] udf: Provide saner default for invalid uid / gid
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Git-commit: 116e5258e4115aca0c64ac0bf40ded3b353ed626
Patch-mainline: v4.17-rc1
References: bsc#1101890

Currently when UDF filesystem is recorded without uid / gid (ids are set
to -1), we will assign INVALID_[UG]ID to vfs inode unless user uses uid=
and gid= mount options. In such case filesystem could not be modified in
any way as VFS refuses to modify files with invalid ids (even by root).
This is confusing to users and not very useful default since such media
mode is generally used for removable media. Use overflow[ug]id instead
so that at least root can modify the filesystem.

Reported-by: Steve Kenton <skenton@ou.edu>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/udf/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 4d671be50059..31d8ce13fa18 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -2111,8 +2111,9 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 	bool lvid_open = false;
 
 	uopt.flags = (1 << UDF_FLAG_USE_AD_IN_ICB) | (1 << UDF_FLAG_STRICT);
-	uopt.uid = INVALID_UID;
-	uopt.gid = INVALID_GID;
+	/* By default we'll use overflow[ug]id when UDF inode [ug]id == -1 */
+	uopt.uid = make_kuid(current_user_ns(), overflowuid);
+	uopt.gid = make_kgid(current_user_ns(), overflowgid);
 	uopt.umask = 0;
 	uopt.fmode = UDF_INVALID_MODE;
 	uopt.dmode = UDF_INVALID_MODE;
-- 
2.16.4