Bug#945497: initramfs-tools: Resume function does not check for swap file

["Keven L. Ates" <atescomp@gmail.com>]

Package: initramfs-tools
Version: 0.133ubuntu10
Severity: normal

Dear Maintainer,

The resume hook script (/usr/share/initramfs-tools/hooks/resume) does not check
for a swap file. It checks for a swap device referenced by the RESUME variable.
The RESUME_OFFSET variable is additionally used to point to a file in the
RESUME device that acts as the swap device. In this case, since RESUME points
to a standard file system, a warning is generated:

  W: initramfs-tools configuration sets RESUME=$RESUME
  W: but no matching swap device is available.

The following contains a possible solution to check for a swap file. It relies
on a set RESUME_OFFSET variable indicating a swap file. At least two files
should be modified: 1) the resume hook script and 2) the mkinitramfs script.

The resume script contains the following line numbered items. The unnumbered
lines contain a possible fix to check for the use of a swap file.

     20 # First check if a location is set and is a valid swap partition.
     21 # If so, the config file will be copied in and there is nothing to do.
     22 if [ -n "$RESUME" ] && [ "$RESUME" != auto ]; then
     23         if [ "$RESUME" = none ]; then
     24                 exit 0
     25         fi
                if resume_dev_node="$(resolve_device "$RESUME")"; then
                        if [ -z "$RESUME_OFFSET" ] && \
                           blkid -p -n swap "$resume_dev_node" >/dev/null 2>&1;
then
                                exit 0
                        fi
                        # Assume RESUME_OFFSET is a proper offset pointing to
                        #   the first data block of an inode in RESUME.
                        # Then, the swap filename should be in /proc/swaps.
                        # Get largest filename that is NOT a /dev/...
                        for resume_filename in $( grep -v ^/dev/ /proc/swaps |
grep ^/ | sort -rnk3 | cut -d " " -f 1 ); do
                                if [ -n "$resume_filename" ] && \
                                   blkid -p -n swap "$resume_filename"
>/dev/null 2>&1; then
                                        exit 0
                                fi
                                break
                        done

                        echo >&2 "W: initramfs-tools configuration sets
RESUME=$RESUME and
                        echo >&2 "W:
RESUME_OFFSET=$RESUME_OFFSET"
                        echo >&2 "W: but no matching swap file is available."
     29         fi
     30
     31         echo >&2 "W: initramfs-tools configuration sets RESUME=$RESUME"
     32         echo >&2 "W: but no matching swap device is available."
     33 fi

Getting a file name from an inode from a block offset might be done, but is
problematic as tools related to this are dependent on the file system.  For
ext*, this could be:

  resume_inode=$( debugfs -R "icheck $RESUME_OFFSET" $resume_dev_node
2>/dev/null | tail -1 | cut -f2 )
  resume_fn=$( debugfs -R "ncheck ${RESUME_INODE}" ${RESUME_DEV} 2>/dev/null |
tail -1 | cut -f2 )

However, this process is not generic and may not be available for every file
system.

Additionally, the mkinitramfs script (/usr/sbin/mkinitramfs) does not export
the RESUME_OFFSET variable.  It should be exported for use by the hook scripts.

    242 # Export environment for hook scripts.
    243 #
    244 export MODULESDIR
    245 export version
    246 export CONFDIR
    247 export DESTDIR
    248 export DPKG_ARCH
    249 export verbose
    250 export MODULES
    251 export BUSYBOX
    252 export COMPCACHE_SIZE
    253 export RESUME
        export RESUME_OFFSET
    254



-- System Information:
Debian Release: buster/sid
  APT prefers eoan-updates
  APT policy: (500, 'eoan-updates'), (500, 'eoan-security'), (500, 'eoan'), (100, 'eoan-backports')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.3.0-23-generic (SMP w/8 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages initramfs-tools depends on:
ii  initramfs-tools-core  0.133ubuntu10
ii  linux-base            4.5ubuntu2

initramfs-tools recommends no packages.

Versions of packages initramfs-tools suggests:
ii  bash-completion  1:2.9-1ubuntu1

-- no debconf information