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run unshare --mount with --propagation unchanged to prevent 'cannot change root filesystem propagation' when running mmdebstrap from inside a chroot

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This commit is contained in:
Johannes Schauer Marin Rodrigues 2021-02-06 10:11:53 +01:00
parent f976dabb51
commit 73cd7cd2e8
Signed by untrusted user: josch
GPG key ID: F2CBA5C78FBD83E1
2 changed files with 44 additions and 2 deletions
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39
coverage.sh
View file

@ -119,7 +119,7 @@ if [ ! -e shared/hooks/eatmydata/customize.sh ] || [ hooks/eatmydata/customize.s
fi
fi
starttime=
total=189
total=190
skipped=0
runtests=0
i=1
@ -518,6 +518,43 @@ else
runtests=$((runtests+1))
fi
# Before running unshare mode as root, we run "unshare --mount" but that fails
# if mmdebstrap itself is executed from within a chroot:
# unshare: cannot change root filesystem propagation: Invalid argument
# This test tests the workaround in mmdebstrap using --propagation unchanged
print_header "mode=root,variant=apt: unshare as root user inside chroot"
cat << END > shared/test.sh
#!/bin/sh
set -eu
export LC_ALL=C.UTF-8
[ "\$(whoami)" = "root" ]
cat << 'SCRIPT' > script.sh
#!/bin/sh
set -eu
rootfs="\$1"
mkdir -p "\$rootfs/mnt"
[ -e /usr/bin/mmdebstrap ] && cp -aT /usr/bin/mmdebstrap "\$rootfs/usr/bin/mmdebstrap"
[ -e ./mmdebstrap ] && cp -aT ./mmdebstrap "\$rootfs/mnt/mmdebstrap"
chroot "\$rootfs" env --chdir=/mnt \
$CMD --mode=unshare --variant=apt \
$DEFAULT_DIST /tmp/debian-chroot.tar $mirror
SCRIPT
chmod +x script.sh
$CMD --mode=root --variant=apt --include=perl,mount \
--customize-hook=./script.sh \
--customize-hook="download /tmp/debian-chroot.tar /tmp/debian-chroot.tar" \
$DEFAULT_DIST /dev/null $mirror
tar -tf /tmp/debian-chroot.tar | sort | diff -u tar1.txt -
rm /tmp/debian-chroot.tar script.sh
END
if [ "$HAVE_QEMU" = "yes" ]; then
./run_qemu.sh
runtests=$((runtests+1))
else
./run_null.sh SUDO
runtests=$((runtests+1))
fi
print_header "mode=root,variant=apt: fail with root without cap_sys_admin"
cat << END > shared/test.sh
#!/bin/sh

7
mmdebstrap
View file

@ -4482,8 +4482,13 @@ sub main() {
# For unshare mode to work we either need to already be the root user
# and then we do not have to unshare the user namespace anymore but we
# need to be able to unshare the mount namespace...
#
# We need to call unshare with "--propagation unchanged" or otherwise
# we get 'cannot change root filesystem propagation' when running
# mmdebstrap inside a chroot for which the root of the chroot is not
# its own mount point.
if ($EFFECTIVE_USER_ID == 0
&& 0 != system 'unshare --mount true 2>/dev/null') {
&& 0 != system 'unshare --mount --propagation unchanged -- true') {
error "unable to unshare the mount namespace";
}
# ...or we are not root and then we need to be able to unshare the user