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New: Extended attributes not applied to filesystem

Buildroot bugzilla at busybox.net 1 participant 6 messages Aug 10, 2018 – Nov 13, 2018

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#0 lore raw

https://bugs.busybox.net/show_bug.cgi?id=11216

Bug ID: 11216
Summary: Extended attributes not applied to filesystem
Product: buildroot
Version: 2018.05
Hardware: All
OS: Linux
Status: NEW
Severity: normal
Priority: P5
Component: Other
Assignee: unassigned at buildroot.uclibc.org
Reporter: ricardo.martincoski at datacom.com.br
CC: buildroot at uclibc.org
Target Milestone: ---

Steps to reproduce:
1) create a config for squashfs with xattrs added by either a device_table or _PERMISSIONS in a package.
An example can be seen on the test case of this series:
http://patchwork.ozlabs.org/project/buildroot/list/?series=59394
2) Build
3) Run test, checking with getcap

Actual results:
The build succeeds without any warning.
But in runtime the xattrs are not in the filesystem.

Expected results:
In runtime, calling getcap shows the xattrs.

Additional info:
This bug occurs on master and 2018.05.x. It does not occur on 2018.02.x, before the use of a per-fs target dir.
makedevs does apply the file capabilities to the $(FS_DIR)/target copy, but the extended attributes are not propagated to the target filesystem.

Hacks (cumulative) to understand the problem:
1) removing "rm -f $(ROOTFS_COMMON_TAR)" from the main Makefile and inspecting the tarball

Quoted 1 line

tvvf rootfs.common.tar --xattrs --xattrs-include='*'

the xattr are not shown.
2) adding "--xattrs --xattrs-include='*'" to ROOTFS_COMMON_TAR_CMD the build succeeds without any warning. Inspecting the tarball the xattrs show up

Quoted 1 line

x: 20 security.capability

But when run testing the xattrs are not there.
3) adding "--xattrs --xattrs-include='*'" to ROOTFS_COMMON_UNTAR_CMD the build succeeds with a warning

Quoted 1 line

File my_file_with_xattr has unrecognised filetype 0, ignoring

Inspecting the tarball the xattr shows up.
But when run testing the file that should have the xattrs is not in the image.

Additional notes (speculation):
- In its source code, tar has some suspicious workarounds for security.capability, but it works fine outside of fakeroot.
- fakeroot 1.23 is out but I didn't tried it.
- It looks like the problem occurs when extracting a tarfile with xattrs inside fakeroot. See below the commands I used to test.
Outside of buildroot I tried using those versions from Ubuntu 18.04:
tar (GNU tar) 1.29
fakeroot version 1.22

Quoted 26 lines
$ mkdir dir
$ touch dir/file
$ fakeroot
# setcap cap_kill+eip dir/file
# getcap dir/file
dir/file = cap_kill+eip
# tar cf archive.tar dir --xattrs
# exit
$ tar tvvf archive.tar --xattrs --xattrs-include='*'
drwxr-xr-x  root/root         0 2018-08-05 23:21 dir/
-rw-r--r--* ricardo/ricardo   0 2018-08-05 23:21 dir/file
  x: 20 security.capability
$ fakeroot
# tar xf archive.tar --xattrs --xattrs-include='*'
# ls -l dir/file
?rw-r--r-- 1 root root 0 ago  5 23:21 dir/file
# file dir/file
dir/file: ERROR: invalid mode 0644
# getcap dir/file
# exit
$ file dir/file
dir/file: empty
$ getcap dir/file
$ sudo tar xf archive.tar --xattrs --xattrs-include='*'
$ getcap dir/file
dir/file = cap_kill+eip
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author
#1 lore raw

[Buildroot] [Bug 11216] Extended attributes not applied to filesystem

https://bugs.busybox.net/show_bug.cgi?id=11216

Yann E. MORIN <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

           Assignee|unassigned at buildroot.uclibc |yann.morin.1998 at free.fr
                   |.org                        |
                 CC|                            |yann.morin.1998 at free.fr
             Status|NEW                         |ASSIGNED
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#3 lore raw

[Buildroot] [Bug 11216] Extended attributes not applied to filesystem

In reply to bugzilla at busybox.net

https://bugs.busybox.net/show_bug.cgi?id=11216

--- Comment #2 from Yann E. MORIN <[email protected]> --- Ricardo, All,

I've sent a second iteration of the series to fix capabilities:
https://patchwork.ozlabs.org/project/buildroot/list/?series=75490

Regards,
Yann E. MORIN.

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#4 lore raw

[Buildroot] [Bug 11216] Capabilities not applied to filesystem

In reply to bugzilla at busybox.net

https://bugs.busybox.net/show_bug.cgi?id=11216

Yann E. MORIN <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

            Summary|Extended attributes not     |Capabilities not applied to
                   |applied to filesystem       |filesystem

--- Comment #3 from Yann E. MORIN <[email protected]> --- Ricardo, All,

Also, I've edited the title of this BZ, because it really relates to capabilities. Our makedevs syntax only allows for specifying capabilities, not arbitrary extended attributes.

Regards,
Yann E. MORIN.

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author
#5 lore raw

[Buildroot] [Bug 11216] Capabilities not applied to filesystem

In reply to bugzilla at busybox.net

https://bugs.busybox.net/show_bug.cgi?id=11216

Yann E. MORIN <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Yann E. MORIN <[email protected]> --- Ricardo, All,

Fixed by:

https://git.buildroot.org/buildroot/commit?id=409d4c3fe9949f01b009712a1a731baf597e0f8d

Thanks for the very detailed report! :-)

Regards,
Yann E. MORIN.

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