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663e27564f
If someone reads /run/host/os-release at the exact same time it is being updated, and it
is large enough, they might read a half-written file. This is very unlikely as
os-release is typically small and very rarely changes, but it is not
impossible.
Bind mount a staging directory instead of the file, and symlink the file
into into, so that we can do atomic file updates and close this gap.
Atomic replacement creates a new inode, so existing bind mounts would
continue to see the old file, and only new services would see the new file.
The indirection via the directory allows to work around this, as the
directory is fixed and never changes so the bind mount is always valid,
and its content is shared with all existing services.
Fixes https://github.com/systemd/systemd/issues/28794
Follow-up for 3f37a82545
153 lines
5.0 KiB
Bash
Executable File
153 lines
5.0 KiB
Bash
Executable File
#!/usr/bin/env bash
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# SPDX-License-Identifier: LGPL-2.1-or-later
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set -ex
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set -o pipefail
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systemd-analyze log-level debug
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export SYSTEMD_LOG_LEVEL=debug
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if [ -f /run/testsuite82.touch3 ]; then
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echo "This is the fourth boot!"
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systemd-notify --status="Fourth Boot"
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rm /run/testsuite82.touch3
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mount
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rmdir /original-root /run/nextroot
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# Check that the fdstore entry still exists
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test "$LISTEN_FDS" -eq 3
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read -r x <&5
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test "$x" = "oinkoink"
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# Check that no service is still around
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test "$(systemctl show -P ActiveState testsuite-82-survive.service)" != "active"
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test "$(systemctl show -P ActiveState testsuite-82-nosurvive.service)" != "active"
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# All succeeded, exit cleanly now
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elif [ -f /run/testsuite82.touch2 ]; then
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echo "This is the third boot!"
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systemd-notify --status="Third Boot"
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rm /run/testsuite82.touch2
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# Check that the fdstore entry still exists
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test "$LISTEN_FDS" -eq 2
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read -r x <&4
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test "$x" = "miaumiau"
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# Upload another entry
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T="/dev/shm/fdstore.$RANDOM"
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echo "oinkoink" >"$T"
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systemd-notify --fd=3 --pid=parent 3<"$T"
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rm "$T"
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# Check that no service is still around
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test "$(systemctl show -P ActiveState testsuite-82-survive.service)" != "active"
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test "$(systemctl show -P ActiveState testsuite-82-nosurvive.service)" != "active"
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# Test that we really are in the new overlayfs root fs
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read -r x </lower
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test "$x" = "miep"
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cmp /etc/os-release /run/systemd/propagate/.os-release-stage/os-release
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grep -q MARKER=1 /etc/os-release
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# Switch back to the original root, away from the overlayfs
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mount --bind /original-root /run/nextroot
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mount
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# Now issue the soft reboot. We should be right back soon.
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touch /run/testsuite82.touch3
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systemctl --no-block soft-reboot
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# Now block until the soft-boot killing spree kills us
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exec sleep infinity
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elif [ -f /run/testsuite82.touch ]; then
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echo "This is the second boot!"
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systemd-notify --status="Second Boot"
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# Clean up what we created earlier
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rm /run/testsuite82.touch
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# Check that the fdstore entry still exists
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test "$LISTEN_FDS" -eq 1
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read -r x <&3
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test "$x" = "wuffwuff"
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# Upload another entry
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T="/dev/shm/fdstore.$RANDOM"
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echo "miaumiau" >"$T"
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systemd-notify --fd=3 --pid=parent 3<"$T"
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rm "$T"
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# Check that no service survived, regardless of the configuration
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test "$(systemctl show -P ActiveState testsuite-82-survive.service)" != "active"
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test "$(systemctl show -P ActiveState testsuite-82-nosurvive.service)" != "active"
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# This time we test the /run/nextroot/ root switching logic. (We synthesize a new rootfs from the old via overlayfs)
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mkdir -p /run/nextroot /tmp/nextroot-lower /original-root
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mount -t tmpfs tmpfs /tmp/nextroot-lower
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echo miep >/tmp/nextroot-lower/lower
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# Copy os-release away, so that we can manipulate it and check that it is updated in the propagate
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# directory across soft reboots. Try to cover corner cases by truncating it.
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mkdir -p /tmp/nextroot-lower/usr/lib
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grep ID /etc/os-release >/tmp/nextroot-lower/usr/lib/os-release
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echo MARKER=1 >>/tmp/nextroot-lower/usr/lib/os-release
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cmp /etc/os-release /run/systemd/propagate/.os-release-stage/os-release
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(! grep -q MARKER=1 /etc/os-release)
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mount -t overlay nextroot /run/nextroot -o lowerdir=/tmp/nextroot-lower:/,ro
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# Bind our current root into the target so that we later can return to it
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mount --bind / /run/nextroot/original-root
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# Now issue the soft reboot. We should be right back soon.
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touch /run/testsuite82.touch2
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systemctl --no-block soft-reboot
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# Now block until the soft-boot killing spree kills us
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exec sleep infinity
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else
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# This is the first boot
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systemd-notify --status="First Boot"
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# Let's upload an fd to the fdstore, so that we can verify fdstore passing works correctly
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T="/dev/shm/fdstore.$RANDOM"
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echo "wuffwuff" >"$T"
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systemd-notify --fd=3 --pid=parent 3<"$T"
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rm "$T"
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# Create a script that can survive the soft reboot by ignoring SIGTERM (we
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# do this instead of the argv[0][0] = '@' thing because that's so hard to
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# do from a shell
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T="/dev/shm/survive-$RANDOM.sh"
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cat >$T <<EOF
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#!/bin/bash
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trap "" TERM
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systemd-notify --ready
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rm "$T"
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exec sleep infinity
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EOF
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chmod +x "$T"
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# This sets DefaultDependencies=no so that it remains running until the
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# very end, and IgnoreOnIsolate=yes so that it isn't stopped via the
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# "testsuite.target" isolation we do on next boot
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systemd-run -p Type=notify -p DefaultDependencies=no -p IgnoreOnIsolate=yes --unit=testsuite-82-survive.service "$T"
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systemd-run -p Type=exec -p DefaultDependencies=no -p IgnoreOnIsolate=yes --unit=testsuite-82-nosurvive.service sleep infinity
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# Now issue the soft reboot. We should be right back soon.
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touch /run/testsuite82.touch
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systemctl --no-block soft-reboot
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# Now block until the soft-boot killing spree kills us
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exec sleep infinity
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fi
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systemd-analyze log-level info
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touch /testok
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systemctl --no-block poweroff
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