udf: Provide saner default for invalid uid / gid

[ Upstream commit 116e5258e4115aca0c64ac0bf40ded3b353ed626 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index ee09c97f3ab29ddec2ac140367a3ea879bec4657..159977ec8e548baed7251ab44de12f68e60f2da4 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -2073,8 +2073,9 @@ 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;