fails to parse gnu tar xattrs (CentOS Docker base image)

[cgwalters]

The CentOS docker base image is created ultimately via a tool that ultimately uses GNU tar. In CentOS, the /usr/bin/ping binary has file capabilities.

We're trying to import this tarball into OSTree which ultimately uses libarchive.

ostree --repo=../repo commit --tar-autocreate-parents -b centos-docker-base --tree=tar=8c3d77a518cbc66dad00ac5b6061a4d7c7f14c3d8b516c7d635642d11418cd29.tar 
error: Ignoring malformed pax extended attribute

Now, ostree is currently treating the warning as fatal, which we could easily change, but at the cost of losing the xattr here. I thought libarchive was able to parse GNU xattrs, but this case seems to fail.

Minimal reproducer looks like:

$ rpm -q tar libarchive
tar-1.28-7.fc24.x86_64
libarchive-3.1.2-17.fc24.x86_64
$ tar -c --xattrs -f ping.tar /usr/bin/ping
$ bsdtar -tf ping.tar 
bsdtar: Ignoring malformed pax extended attribute
usr/bin/ping
bsdtar: Error exit delayed from previous errors.

[jsonn]

Can you attach an example tar file please?

[cgwalters]

ping.tar.gz

[cgwalters]

I generated this by simply doing (with the same binaries as above, though this time as root so I could easily set the security attribute):

# touch ping
# setfattr -n security.capability -v test
# tar -c --xattrs -f ping.tar ping
# gzip ping.tar

[kientzle]

A long time ago, star and libarchive implemented xattr support in slightly different ways. GNU tar chose to copy their implementation from star rather than from libarchive.

There's a pull request to add the ability to read star-format xattr entries to libarchive. I've not yet had time to review it thoroughly, but it's certainly on my to-do list.

[cgwalters]

#691

[mmatuska]

Is this still an issue after #691 has been merged?

[kientzle]

This should have been fixed with #691