** Description changed: + [Impact] + unsquashfs does not preserve the stickybit when run as non-root (unlike other archive tools, like tar). While this is a bug in and of itself, it causes snaps with sticky directories to fail automated review because the requashed snap has the bit stripped and the resquashed snap as a result has a different checksum. + + The fix is to attempt the chmod with the stickybit and if it fails with + EPERM when not root, try again without the stickybit. + + [Test Case] + + 1. create a squashfs with a sticky dir: + + $ mkdir -p /tmp/foo/sticky-dir + $ chmod 1777 /tmp/foo/sticky-dir + $ mksquashfs /tmp/foo test.squash -all-root + + 2. see that the squashfs has the sticky dir in the squash: + + $ unsquashfs -lls ./test.squash + ... + drwxrwxrwt root/root 3 2018-07-05 16:03 squashfs-root/sticky-dir + + 3. unsquash the squash as non-root: + + $ unsquashfs test.squash + + 4. verified the stickybit is set: + + $ ls -ld squashfs-root/sticky-dir/ + drwxrwxrwt 2 jamie jamie 4096 Jul 5 16:07 squashfs-root/sticky-dir/ + + Without the SRU, the directory is 0777 and the file 0775: + + $ ls -ld squashfs-root/sticky-dir/ + drwxrwxrwx 2 jamie jamie 4096 Jul 5 16:07 squashfs-root/sticky-dir/ + + [Regression Potential] + + Due to the fallback behavior, the regression potential is considered + low. Furthermore, because the non-root user is still the owner of the + resulting unpacked sticky directories, there is no problem with being + able to remove the unpacked directories on error, etc. + + [ Original description ] From https://sourceforge.net/p/squashfs/mailman/message/36343213/: "This set is an attempt to preserve the sticky bit when running unsquashfs as a non-root user. My main motivation for these changes is to improve reproducability when doing a sequence of "unsquashfs -> mksquashfs" as a non-root user but I think there's even more value in preserving the sticky bit in the case of a squashfs image containing a world-writable directory filled with files owned by a single user. Dropping the sticky bit could be considered to be a real bug in that scenario."
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1779914 Title: unsquashfs does not preserve sticky bit when run as non-root To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/squashfs-tools/+bug/1779914/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
