Re: [PATCH 2/2] images: wic: do not call wic with sudo anymore

[Henning Schild <henning.schild@siemens.com>]

I still prefer the almighty big sudo, this patch adds complexity and is
a hack. But i also think that touching contrib code in _any_ way is so
evil that any hack should be considered to avoid it.

Henning

Am Wed, 31 Jan 2018 16:48:38 +0100
schrieb Henning Schild <henning.schild@siemens.com>:

> Issues:
>   1. wic was called under sudo
>   2. wic and its plugins can use sudo to do whatever they want
> 
> Impact:
>   Issue 1 is addressed, but Issue 2 has always been there and has
> come to stay.
> 
> Signed-off-by: Henning Schild <henning.schild@siemens.com>
> ---
>  meta/classes/wic-img.bbclass | 17 ++++++++++++++++-
>  scripts/wic_fakeroot         | 37
> ++++++++++++++++++++++--------------- 2 files changed, 38
> insertions(+), 16 deletions(-)
> 
> diff --git a/meta/classes/wic-img.bbclass
> b/meta/classes/wic-img.bbclass index 72779eb..444e003 100644
> --- a/meta/classes/wic-img.bbclass
> +++ b/meta/classes/wic-img.bbclass
> @@ -59,7 +59,22 @@ do_wic_image() {
>      export BUILDDIR="${BUILDDIR}"
>      export MTOOLS_SKIP_CHECK=1
>  
> -    sudo -E
> PATH="$PATH:/builder/isar/bitbake/bin:/builder/isar/scripts" /builder/isar/scripts/wic
> create ${WKS_FILE} --vars "${STAGING_DIR}/${MACHINE}/imgdata/" -o
> ${DEPLOY_DIR_IMAGE} -e ${IMAGE_BASENAME} ${WIC_CREATE_EXTRA_ARGS}
> +    # Play a dirty trick to redirect "du" and "mkfs.*" to FAKEROOTCMD
> +    WTOOLS_SYSROOT="${TMPDIR}/trick_wic/"
> +    mkdir -p ${WTOOLS_SYSROOT}/sbin
> +    mkdir -p ${WTOOLS_SYSROOT}/usr/bin
> +    for fstype in btrfs ext2 ext3 ext4 vfat; do
> +    	ln -sf /builder/isar/scripts/${FAKEROOTCMD} \
> +	    ${WTOOLS_SYSROOT}/sbin/mkfs.${fstype}
> +    done
> +    ln -sf /builder/isar/scripts/${FAKEROOTCMD} \
> +        ${WTOOLS_SYSROOT}/usr/bin/du
> +
> +    echo "RECIPE_SYSROOT_NATIVE=\"${WTOOLS_SYSROOT}\"" >> \
> +        ${STAGING_DIR}/${MACHINE}/imgdata/wic-tools.env
> +
> +    export
> PATH="${WTOOLS_SYSROOT}/sbin:${WTOOLS_SYSROOT}/usr/sbin:${WTOOLS_SYSROOT}/usr/bin:${PATH}"
> +    /builder/isar/scripts/wic create ${WKS_FILE} --vars
> "${STAGING_DIR}/${MACHINE}/imgdata/" -o ${DEPLOY_DIR_IMAGE} -e
> ${IMAGE_BASENAME} ${WIC_CREATE_EXTRA_ARGS} } 
>  addtask wic_image before do_build after do_copy_boot_files
> diff --git a/scripts/wic_fakeroot b/scripts/wic_fakeroot
> index 9e01c38..01865a0 100755
> --- a/scripts/wic_fakeroot
> +++ b/scripts/wic_fakeroot
> @@ -1,10 +1,11 @@
>  #!/usr/bin/env python3
>  #
>  # wic needs a FAKEROOT cmd to run, the default is pseudo. In Isar we
> do/can not -# use pseudo. And we call wic as root to begin with, so
> this script could be a -# dummy doing nothing. It is almost a
> dummy ... -#
> -# If the fsck hack ever becomes obsolete, FAKEROOTCMD ?= "true;" can
> be used +# use pseudo at the moment.
> +# All wic calls to exec_native_cmd will end up here, if they wanted
> pseudo. +# They will get executed under sudo.
> +# In addition we prepend "du"s and "mkfs"s with a sudo, just like a
> Isar +# specific patch did before.
>  #
>  # This software is a part of Isar.
>  # Copyright (C) 2018 Siemens AG
> @@ -15,23 +16,29 @@ import shutil
>  import subprocess
>  
>  args = sys.argv
> -args.pop(0)
> -cmd = args[0]
> +args[0] = os.path.basename(args[0])
> +
> +if not (args[0].startswith('mkfs.') or args[0] == 'du'):
> +    # the wrapper was not called directly and not for one of the
> known
> +    # hacks
> +    if args[0] != 'wic_fakeroot':
> +        sys.exit(1)
> +    args.pop(0)
>  
> -# expect to be running as root
> -# we could loosen that and execv(sudo, args) but even some early
> -# "du"s fail, which do not use the fakeroot-wrapper
> -#  i.e. in wics partition.py the "du -ks" fails on
> -#    var/cache/apt/archives/partial
> -#    rootfs/root ...
> -assert 'root' == os.environ["USER"]
> +cmd = args[0]
>  
>  # e2fsck <= 1.43.5 returns 1 on non-errors (stretch and before
> affected) # treat 1 as safe ... the filesystem was successfully
> repaired and is OK if cmd.startswith('fsck.'):
> -    ret = subprocess.call(args)
> +    ret = subprocess.call(['sudo'] + args)
>      if ret == 0 or ret == 1:
>          sys.exit(0)
>      sys.exit(ret)
>  
> -os.execv(shutil.which(cmd), args)
> +# now remove the previous 3 entries from PATH, the ones we used to
> trick some guys in here +path =
> ':'.join(os.environ['PATH'].split(':')[3:]) +path +=
> ":/builder/isar/bitbake/bin:/builder/isar/scripts" +
> +args = ['-E', 'PATH="%s"' % path ] + args
> +
> +os.execv(shutil.which('sudo'), args)