[Bug 15875] New: Add options to disable POSIX acl for ext2/ext3/ext4 file systems

[Bug 15875] New: Add options to disable POSIX acl for ext2/ext3/ext4 file systems

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=15875

           Summary: Add options to disable POSIX acl for ext2/ext3/ext4
                    file systems
           Product: File System
           Version: 2.5
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: ext2
        AssignedTo: fs_ext2@kernel-bugs.osdl.org
        ReportedBy: t.artem@mailcity.com
        Regression: No


VFAT becomes less of an option for many hardware producers and many of them
will be glad to embrace ext2/ext3/ext4 filesystems but they have an inherent
problem, they enforce POSIX ACLs.

So, imagine a situation when Peter who has UID=63555 (he's in a corporate
network and that's his real UID according to LDAP) formats his flash drive
using ext2/ext3/ext4 filesystem, then uses sudo to recursively chown the whole
filesystem for his own possession.

Now, Peter comes to a less savvy Alice who wasn't given root permissions on her
PC and she tries to open Peter's flash stick. Oops, Alice cannot open or read
any file on it. I can come up with ten other different scenarios when ACLs are
superfluous.

Taking this situation into consideration it becomes clear that ACL's for
removable storage is more a hassle than a security feature.

So, I strongly suggest implementing a flag which tells the kernel to disregard
all file/directory permissions on the aforementioned FS's.

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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Artem S. Tashkinov <t.artem@mailcity.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Add options to disable      |Add an option to disable
                   |POSIX acl for               |file/directory permissions
                   |ext2/ext3/ext4 file systems |for ext2/ext3/ext4 file
                   |                            |systems




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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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Andrew Morton <akpm@linux-foundation.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |akpm@linux-foundation.org




--- Comment #1 from Andrew Morton <akpm@linux-foundation.org>  2010-04-29 09:47:21 ---
Set CONFIG_EXT2_FS_POSIX_ACL to `n'?

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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--- Comment #2 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-04-29 09:53:36 ---
Doesn't that require kernel recompilation? Besides we still need rwx ugo
permissions for local filesystems.

Or maybe I didn't formulate the bug description correctly ;)

Again, I want a 'mount' option which disables usual UNIX permissions which are
RWX UGO (and, of course, UID/GID).

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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https://bugzilla.kernel.org/show_bug.cgi?id=15875





--- Comment #3 from Andrew Morton <akpm@linux-foundation.org>  2010-04-29 09:56:27 ---
ext2 supports `mount -o noacl'.

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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--- Comment #4 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-04-29 10:16:06 ---
It doesn't work:

# dd if=/dev/zero of=ext2.img bs=100M count=1
...
# mke2fs ext2.img -> y
...
# mount -o loop,noacl ext2.img loop
# mount | grep noacl
/dev/loop0 on /tmp/loop type ext2 (rw,noacl)

$ cd /tmp/loop
$ touch test
touch: cannot touch `test': Permission denied

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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--- Comment #5 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-04-29 11:11:05 ---
Probably it's worth implementing a more generous solution for all FS's on VFS
level, i.e. something like:

man mount:

FILESYSTEM INDEPENDENT MOUNT OPTIONS
       Some of these options are only useful when they appear in the /etc/fstab
file.

       Some of these options could be enabled or disabled by default in the
system kernel. To check the current setting see  the  options  in
       /proc/mounts.

       The  following  options  apply to any filesystem that is being mounted
(but not every filesystem actually honors them - e.g., the sync
       option today has effect only for ext2, ext3, fat, vfat and ufs):

***
       asroot  Map all uids and gids to the root user. It's useful
       for mounting removable storage  media.  Note that all files
       and directories created in this mode will be owned by root.

***

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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Alexey Dobriyan <adobriyan@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adobriyan@gmail.com




--- Comment #6 from Alexey Dobriyan <adobriyan@gmail.com>  2010-05-06 12:36:33 ---
This would be "uid=", "gid=" options VFAT-style.

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[Bug 15875] Add an option to disable file/directory permissions for ext2/ext3/ext4 file systems

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--- Comment #7 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-05-07 07:09:07 ---
Whatever fits you, however don't forget that there are immutable and appendable
only flags for ext2/3/4 and they should probably dismissed too.

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[Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

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https://bugzilla.kernel.org/show_bug.cgi?id=15875


Artem S. Tashkinov <t.artem@mailcity.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fs_vfs@kernel-bugs.osdl.org
          Component|ext2                        |VFS
            Summary|Add an option to disable    |Add an option to disable
                   |file/directory permissions  |file/directory permissions
                   |for ext2/ext3/ext4 file     |for ACL'ed file systems
                   |systems                     |




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[Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

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--- Comment #8 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-05-31 07:54:57 ---
I cannot change the assignee field of this bug report:

"You tried to change the Assignee field from fs_ext2@kernel-bugs.osdl.org  to
fs_vfs@kernel-bugs.osdl.org  , but only the assignee of the bug, or a user with
the required permissions may change that field."

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[Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

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https://bugzilla.kernel.org/show_bug.cgi?id=15875





--- Comment #9 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-07-04 14:25:46 ---
Created an attachment (id=27012)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=27012)
Tentative patch

Probably it's not difficult to write an implementation, but I have no idea how
to check mount flags in namei.c inode_permission() function.

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[Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

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https://bugzilla.kernel.org/show_bug.cgi?id=15875





--- Comment #10 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-11-04 12:04:43 ---
I've received an e-mail from some guy, it seems like he/she doesn't want or
cannot use bugzilla, so I'm citing it as is:

> Dear Mr.Tashkinov:
> 
> Sorry for contacting you this way.
> 
> I would find it very useful if the flag of enabling or disabling the 
> permissions was written in the hard drive at format time.
> 
> I hope you find useful the suggestion.
> 
> Yours faithfully,
> 
> Guy name

(I'm not disclosing his/her name because probably he/she wants to remain
anonymous).

But to my mind his/her suggestion cries for a new bug report.

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[Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

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Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tytso@mit.edu




--- Comment #11 from Theodore Tso <tytso@mit.edu>  2010-11-04 15:48:22 ---
So this bug report is highly confused.  Reading the original request, I think
what the original poster was requesting was actually a way of disabling all
access controls, and ACL's (meaning Access Control Lists) has nothing to do
with this at all.

Ideally I think this should be a VFS-level mount option (like read-only,
noatime) so that it's not an ext4 specific option.  But if we can't get
consensus across other file system developer teams, doing it as an ext4
specific mount option is a possibility.

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Re: [Bug 15875] Add an option to disable file/directory permissions for ACL'ed file systems

[Chris Lee]

On 04/11/10 15:48, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=15875
>
>
> Theodore Tso<tytso@mit.edu>  changed:
>
>             What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                   CC|                            |tytso@mit.edu
>
>
>
>
> --- Comment #11 from Theodore Tso<tytso@mit.edu>   2010-11-04 15:48:22 ---
> So this bug report is highly confused.  Reading the original request, I think
> what the original poster was requesting was actually a way of disabling all
> access controls, and ACL's (meaning Access Control Lists) has nothing to do
> with this at all.
>
> Ideally I think this should be a VFS-level mount option (like read-only,
> noatime) so that it's not an ext4 specific option.  But if we can't get
> consensus across other file system developer teams, doing it as an ext4
> specific mount option is a possibility.
>
I know this is an old post I am dragging up but I have not seen any further 
discussion and I would like to see the a solution for the following use case:
I grab the SD card out of a friends camera which stores images on an extX file 
system and shove it into my PC. My PC makes all the files owned by me so that I 
can access them, just like today with FAT based sd cards.
If this is done at the VFS level then how is my PC going to know that the file 
system on the SD card has permissions that should be ignored?
Or should things like cameras all just write files with owner id 0 and 
permissions set to 777?
My issue with this is when I change the permissions by using some broken 
software and then put it back in the camera will it be able to store the images 
in a permission modified directory? or will the owner of the camera have 
problems later on when they try to get the content off the card?

It would be nice if the file system had a "data in this file system is for 
anyone who can get their hands on it" mode that was well defined so that device 
manufacturers would feel safer using it for mass end user use.

Regards,
Chris.

[Bug 15875] Add an option to disable file/directory access controls for USB stick-type storage devices

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=15875


Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Add an option to disable    |Add an option to disable
                   |file/directory permissions  |file/directory access
                   |for ACL'ed file systems     |controls for USB stick-type
                   |                            |storage devices




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--- Comment #12 from Artem S. Tashkinov <t.artem@mailcity.com>  2010-11-09 20:41:45 ---
Yes, Theodore, you are quite right.

At first I wanted this option to be available only for ext{2,3,4} filesystems,
but then I realized it's good to have it on a VFS level (some people may
actually use any other FS on their removable mass storage devices).

And since this bug doesn't progress anywhere can you raise this question on
LKML? After all you are a core kernel developer, so people will likely listen
to your proposition more attentively.

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[Bug 15875] Add an option to disable file/directory access controls for USB stick-type storage devices

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sergey <sergey-feo@yandex.ru> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sergey-feo@yandex.ru




--- Comment #13 from sergey <sergey-feo@yandex.ru>  2010-12-09 16:50:51 ---
Excuse me for my bad English :-)

Now we have many variants that can be implemented.

1. Disable rights control at VFS level or at formatting time. 
a) at VFS level only (FS-independent)
b) at formatting time only (FS-dependent)
c) both at VFS level and at formatting time (FS level). Default option is
"rights on". It can be overwritted at FS level during formatting and then it
can be overwritted at VFS level during mounting.

My vote is 1c.

2. In case of VFS-level option - what UID, GID and mode will be set for created
files and directories?
a) as always. Independ of option "Disable rights control".
b) user root, group root, rwxrwxrwx.
c) something like umask option will be implemented.

In other words, we mount FS with disabling rights. Then we write something on
it. Then we remount FS with enabling rights. What permissions will we see?

My vote is 2a.

3. Lets imagine that we have ext3 filesistem mounted with "Disable right
control" option enabled. We run ls -l - what permissions will it show?
a) rwxrwxrwx
b) rwArwArwA, where A = true when at least one of "executable" bits on disk is
set to "true".

In other words, will our new option affect all rights or only read-write but
not exec?   

My vote is 3a (simple solution).

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Artem S. Tashkinov <t.artem@mailcity.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|fs_ext2@kernel-bugs.osdl.or |fs_vfs@kernel-bugs.osdl.org
                   |g                           |




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