shiftfs: allow changing ro/rw for subvolumes

[Christian Brauner]

SRU Justification

Impact: Stéphane reported regression for btrfs workloads employing shiftfs.
Unprivileged users can already toggle whether a subvolume will be ro or
rw. This is broken on current shiftfs as we haven't whitelisted these
ioctls().

Fix: To enable this with shiftfs we need to whitelist BTRFS_IOC_FS_INFO,
BTRFS_IOC_SUBVOL_GETFLAGS, BTRFS_IOC_SUBVOL_SETFLAGS. All of them should
be safe for unprivileged users.

Regression Potential: Limited to shiftfs.

Test Case: Tested with LXD running shiftfs on top of btrfs and verified
btrfs subvolumes can be made ro or rw.

[Christian Brauner (cbrauner)]

See
https://git.launchpad.net/~cbrauner/ubuntu/+source/linux/+git/disco/log/?h=2019-05-07/shiftfs_btrfs_ioctls

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1832316

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Christian Brauner (cbrauner)]

Sent patch:
https://lists.ubuntu.com/archives/kernel-team/2019-June/101305.html

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-disco' to 'verification-done-disco'. If the problem still exists, change the tag 'verification-needed-disco' to 'verification-failed-disco'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.2.0-8.9

---------------
linux (5.2.0-8.9) eoan; urgency=medium

  * linux: 5.2.0-8.9 -proposed tracker (LP: #1835700)

  * Miscellaneous Ubuntu changes
    - [Packaging] replace zfs and spl build with zfs 0.8.1-1ubuntu1
    - SAUCE: test_bpf: remove expected fail for Ctx heavy transformations test on
      s390
    - SAUCE: add -fcf-protection=none to retpoline flags
    - SAUCE: usbip: ensure strings copied using strncpy are null-terminated
    - SAUCE: usbip: add -Wno-address-of-packed-member to EXTRA_CFLAGS
    - SAUCE: perf jvmti: ensure strncpy result is null-terminated
    - update dkms package versions
    - add removed zfs modules to modules.ignore

  [ Upstream Kernel Changes ]

  * Rebase to v5.2

 -- Seth Forshee <email address hidden> Mon, 08 Jul 2019 07:13:41 -0500

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.0.0-21.22

---------------
linux (5.0.0-21.22) disco; urgency=medium

  * linux: 5.0.0-21.22 -proposed tracker (LP: #1834902)

  * Disco update: 5.0.15 upstream stable release (LP: #1834529)
    - net: stmmac: Use bfsize1 in ndesc_init_rx_desc
    - Drivers: hv: vmbus: Remove the undesired put_cpu_ptr() in hv_synic_cleanup()
    - ubsan: Fix nasty -Wbuiltin-declaration-mismatch GCC-9 warnings
    - staging: greybus: power_supply: fix prop-descriptor request size
    - staging: wilc1000: Avoid GFP_KERNEL allocation from atomic context.
    - staging: most: cdev: fix chrdev_region leak in mod_exit
    - staging: most: sound: pass correct device when creating a sound card
    - ASoC: tlv320aic3x: fix reset gpio reference counting
    - ASoC: hdmi-codec: fix S/PDIF DAI
    - ASoC: stm32: sai: fix iec958 controls indexation
    - ASoC: stm32: sai: fix exposed capabilities in spdif mode
    - ASoC: stm32: sai: fix race condition in irq handler
    - ASoC:soc-pcm:fix a codec fixup issue in TDM case
    - ASoC:hdac_hda:use correct format to setup hda codec
    - ASoC:intel:skl:fix a simultaneous playback & capture issue on hda platform
    - ASoC: dpcm: prevent snd_soc_dpcm use after free
    - ASoC: nau8824: fix the issue of the widget with prefix name
    - ASoC: nau8810: fix the issue of widget with prefixed name
    - ASoC: samsung: odroid: Fix clock configuration for 44100 sample rate
    - ASoC: rt5682: Check JD status when system resume
    - ASoC: rt5682: fix jack type detection issue
    - ASoC: rt5682: recording has no sound after booting
    - ASoC: wm_adsp: Add locking to wm_adsp2_bus_error
    - clk: meson-gxbb: round the vdec dividers to closest
    - ASoC: stm32: dfsdm: manage multiple prepare
    - ASoC: stm32: dfsdm: fix debugfs warnings on entry creation
    - ASoC: cs4270: Set auto-increment bit for register writes
    - ASoC: dapm: Fix NULL pointer dereference in snd_soc_dapm_free_kcontrol
    - drm/omap: hdmi4_cec: Fix CEC clock handling for PM
    - IB/hfi1: Clear the IOWAIT pending bits when QP is put into error state
    - IB/hfi1: Eliminate opcode tests on mr deref
    - IB/hfi1: Fix the allocation of RSM table
    - MIPS: KGDB: fix kgdb support for SMP platforms.
    - ASoC: tlv320aic32x4: Fix Common Pins
    - drm/mediatek: Fix an error code in mtk_hdmi_dt_parse_pdata()
    - perf/x86/intel: Fix handling of wakeup_events for multi-entry PEBS
    - perf/x86/intel: Initialize TFA MSR
    - linux/kernel.h: Use parentheses around argument in u64_to_user_ptr()
    - iov_iter: Fix build error without CONFIG_CRYPTO
    - xtensa: fix initialization of pt_regs::syscall in start_thread
    - ASoC: rockchip: pdm: fix regmap_ops hang issue
    - drm/amdkfd: Add picasso pci id
    - drm/amdgpu: Adjust IB test timeout for XGMI configuration
    - drm/amdgpu: amdgpu_device_recover_vram always failed if only one node in
      shadow_list
    - drm/amd/display: fix cursor black issue
    - ASoC: cs35l35: Disable regulators on driver removal
    - objtool: Add rewind_stack_do_exit() to the noreturn list
    - slab: fix a crash by reading /proc/slab_allocators
    - drm/sun4i: tcon top: Fix NULL/inv...