Bug#953563: initramfs-tools-core: The hook-function copy_file should not canonicalize target directory if $3 is given

[Roman Gruber <roman.gruber@inf.unibe.ch>]

Package: initramfs-tools-core
Version: 0.133+deb10u1
Severity: normal

Dear Maintainer,

   * What led up to the situation?

Implementing a shutdown initramfs with busybox support. In the script preparing
the initramfs in /run/initramfs, I sourced /usr/share/initramfs-tools/hooks/zz-
busybox (This is from package busybox). This script is called with set -e,
therefore aborting in case of an error. In the last block of the script there
are hard links created for all the utilities busybox does provide (ls, cp,
...). These are linked to /bin/busybox (inside the initramfs). But since the
hook-function copy_file canonicalizes all paths (/bin/busybox becomes
/usr/bin/busybox), this line fails (line 38 in /usr/share/initramfs-
tools/hooks/zz-busybox).

The copy process of the busybox binary is called "copy_exec /bin/busybox
/bin/busybox". With a target path provided.

   * What exactly did you do (or not do) that was effective (or
     ineffective)?

For me I copied zz-busybox and adjusted it for my purpose. But the problem lies
in the hook function copy_file, not in the hook script of busybox.

   * What was the outcome of this action?

The script failed to link basic utilities to busybox inside the initramfs.

   * What outcome did you expect instead?

Correct links to busybox for all provided utilities.



-- System Information:
Debian Release: 10.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.4.0-0.bpo.3-amd64 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=de_CH.UTF-8, LC_CTYPE=de_CH.UTF-8 (charmap=UTF-8), LANGUAGE=de_CH.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages initramfs-tools-core depends on:
ii  coreutils    8.30-3
ii  cpio         2.12+dfsg-9
ii  e2fsprogs    1.45.5-2~bpo10+1
ii  klibc-utils  2.0.6-1
ii  kmod         26-1
ii  udev         244-3~bpo10+1

Versions of packages initramfs-tools-core recommends:
ii  busybox  1:1.30.1-4
ii  pigz     2.4-1

Versions of packages initramfs-tools-core suggests:
ii  bash-completion  1:2.8-6

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