initramfs: zfsunlock hook breaks /usr/bin

[pzakha]

When running update-initramfs -u, we get the following output:

$ sudo update-initramfs -u
update-initramfs: Generating /boot/initrd.img-5.4.0-1025-aws
mkdir: cannot create directory ‘/var/tmp/mkinitramfs_x4d2p6//usr/bin’: File exists
cp: failed to access '/var/tmp/mkinitramfs_x4d2p6//usr/bin/dirname': Not a directory
mkdir: cannot create directory ‘/var/tmp/mkinitramfs_x4d2p6//usr/bin’: File exists
cp: failed to access '/var/tmp/mkinitramfs_x4d2p6//usr/bin/env': Not a directory
mkdir: cannot create directory ‘/var/tmp/mkinitramfs_x4d2p6/usr/bin’: File exists
touch: cannot touch '/var/tmp/mkinitramfs_x4d2p6/usr/bin/net': Not a directory
chmod: cannot access '/var/tmp/mkinitramfs_x4d2p6/usr/bin/net': Not a directory

When the initramfs archive is created or updated, it runs a bunch of hooks in /usr/share/initramfs-tools/hooks. A new hook introduced by #10027, zfsunlock, copies a new file in the /usr/bin directory of the initramfs archive. The problem is that when that hook is executed the /usr/bin directory doesn't exist, so instead of copying the script into the /usr/bin directory, it creates a new /usr/bin file with the contents of that script.

Description

The copy_exec() function expects that the full path of the target file is passed rather than just the directory, and will take care of creating the underlying directories if they don't exist.

How Has This Been Tested?

The issue was detected on Ubuntu 18.04 running with zfs on root, using initramfs-tools version 0.130ubuntu3.11. I've modified the hook installed under /usr/share/initramfs-tools/hooks/zfsunlock, re-ran update-initramfs -u and made sure the system can still boot.

Additional thoughts

We may want to consider running all zfs hooks with -e, so that they fail if any sub-command fails. In this case, the errors come from the "zfs" hook, which seems to run after the "zfsunlock" hook.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[pzakha]

cc: @terem42

[behlendorf]

Looks good. This is the same as the preferred fix proposed in #10448.

[terem42]

Looks good. This is the same as the preferred fix proposed in #10448.

Agree, there was a missing slash on copy_exec command, covered by earlier fix.
Should be like this:
copy_exec /usr/share/initramfs-tools/zfsunlock /usr/bin/

[pzakha]

@terem42 Just a note regarding copy_exec, the 2nd argument should include the name of the executable rather than just the directory. See the function in initramfs-tools:

# $1 = executable/shared library to copy to initramfs, with dependencies
# $2 (optional) Name for the file on the initramfs
# Location of the image dir is assumed to be $DESTDIR
# We never overwrite the target if it exists.
copy_exec() {