On Wednesday, 1 May 2019 03:32:21 BST Bill Kenworthy wrote: > Got sidetracked - turns out fuse and exfat on usb do not play well with > mounts as a user due to changes late last year. It can now only be > mounted/unmounted by root. > > The second part (also due to fuse) is that to stop fuse (silently as ls > still showed the execute bit set) from interfering with execution of > files on the mounted device) it must be mounted as the user under a user > owned directory such as /home/user (mount cannot deal with this - it did > in the past, but something has changed). So the solution is to mount > via root as the user you want (via sudo) under a mount point in the > users home. This may all be unique to fuse-exfat, and which versions of > everything involved as I saw one email on the mechanics of the changes > saying fat is handled a little differently due to a different use > scenario. And ext2/3/4 etc don't have the problem at all. Auto-mount > on device plugin still doesn't happen so thats next on my list. > > /etc/fstab: > > /dev/sda1 /home/myuser/mnt auto > rw,auto,exec,uid=1000,gid=1000,users,user=myuser 0 0 > > > BillK
exFAT and VFAT are mounted with different permissions by udisks, without
overriding options in fstab or command line.
A random file in exFAT:
$ stat /run/media/michael/VERBATIM32G/blah
File: /run/media/michael/VERBATIM32G/blah
Size: 32768 Blocks: 64 IO Block: 4096 regular file
Device: 811h/2065d Inode: 19 Links: 1
Access: (0777/-rwxrwxrwx) Uid: ( 1000/ michael) Gid: ( 1002/ michael)
Access: 2018-06-08 11:20:50.000000000 +0100
Modify: 2015-08-24 12:50:56.000000000 +0100
Change: 2015-08-24 12:50:56.000000000 +0100
Birth: -
A random file in FAT:
$ stat /run/media/michael/CRUCIAL-8G/blah
File: /run/media/michael/CRUCIAL-8G/blah
Size: 1731366 Blocks: 3384 IO Block: 4096 regular file
Device: 810h/2064d Inode: 124 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/ michael) Gid: ( 1002/ michael)
Access: 2019-04-08 01:00:00.000000000 +0100
Modify: 2007-08-25 22:46:42.000000000 +0100
Change: 2019-04-08 14:04:54.000000000 +0100
Birth: -
Ditto for directories.
exFAT:
$ stat /run/media/michael/VERBATIM32G/Foo
File: /run/media/michael/VERBATIM32G/Foo
Size: 32768 Blocks: 64 IO Block: 4096 directory
Device: 811h/2065d Inode: 24 Links: 1
Access: (0777/drwxrwxrwx) Uid: ( 1000/ michael) Gid: ( 1002/ michael)
Access: 2018-02-11 17:22:52.000000000 +0000
Modify: 2018-02-11 17:22:54.000000000 +0000
Change: 2018-02-11 17:22:54.000000000 +0000
Birth: -
FAT:
$ stat /run/media/michael/CRUCIAL-8G/Foo
File: /run/media/michael/CRUCIAL-8G/Foo
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: 810h/2064d Inode: 79 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( 1000/ michael) Gid: ( 1002/ michael)
Access: 2019-04-08 01:00:00.000000000 +0100
Modify: 2019-04-08 14:43:26.000000000 +0100
Change: 2019-04-08 14:43:26.000000000 +0100
Birth: -
The mount options are different as shown below.
exFAT:
$ findmnt -oOPTIONS /dev/sdb1
OPTIONS
rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,
blksize=4096
FAT:
$ findmnt -oOPTIONS /dev/sdb
OPTIONS
rw,nosuid,nodev,relatime,uid=1000,gid=1002,fmask=0022,dmask=0022,codepage=437,
iocharset=iso8859-1,shortname=mixed,showexec,utf8,flush,errors=remount-ro
In the above examples I used udisksctl to mount the devices. I understand
Gnome expose via Gvfs an API to handle I/O to block devices, which desktop
applications can plug into without performing raw kernel calls to hardware
devices (like e.g. /bin/mount does). I don't run Gnome and am not familiar
with its internals to know how similar it is with udisksctl.
Regarding mounting with udisksctl I don't know why exFAT and VFAT are
different, but the udisksctl man page provides this revealing information on
the mount permissions allowed:
The device will be mounted with a safe set of default options. You
can influence the options passed to the mount(8) command with
--options. Note that only safe options are allowed - requests with
inherently unsafe options such as suid or dev that would allow the
caller to gain additional privileges, are rejected.
HTH.
--
Regards,
Mick
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