[PATCH v2 0/6] export/fuse: Allow other users access to the export

[Max Reitz <mreitz@redhat.com>]

Hi,

The v1 cover letter is here:
https://lists.nongnu.org/archive/html/qemu-block/2021-06/msg00730.html

In v2, I changed the following:
- default_permissions is now passed always.  This is the right thing to
  do regardless of whether allow_other is active or not.

- allow_other is no longer a bool, but an off/on/auto enum.  `auto` is
  the default, in which case we will try to mount the export with
  allow_other first, and then fall back to mounting it without.

- Changing the file mode is now possible even without allow_other
  (because default_permissions is always active now), but only for the
  user/owner.  Giving the group or others any permissions only makes
  sense with allow_other, the same applies to changing the UID or GID.
  Giving a read-only export +w makes no sense and hence yields an EROFS
  error now.

- I decided just testing some default_permission quirks is boring.  So
  the new fuse-allow-other iotest does rely on `sudo -n -u nobody`
  working now, and actually tests what allow_other is supposed to do.
  (Also, it is skipped if allow_other does not work.)


git-backport-diff against v1:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/6:[down] 'export/fuse: Pass default_permissions for mount'
002/6:[0089] [FC] 'export/fuse: Add allow-other option'
003/6:[----] [--] 'export/fuse: Give SET_ATTR_SIZE its own branch'
004/6:[0039] [FC] 'export/fuse: Let permissions be adjustable'
005/6:[down] 'iotests/308: Test +w on read-only FUSE exports'
006/6:[down] 'iotests/fuse-allow-other: Test allow-other'


Max Reitz (6):
  export/fuse: Pass default_permissions for mount
  export/fuse: Add allow-other option
  export/fuse: Give SET_ATTR_SIZE its own branch
  export/fuse: Let permissions be adjustable
  iotests/308: Test +w on read-only FUSE exports
  iotests/fuse-allow-other: Test allow-other

 qapi/block-export.json                        |  33 +++-
 block/export/fuse.c                           | 121 +++++++++---
 tests/qemu-iotests/308                        |  20 +-
 tests/qemu-iotests/308.out                    |   6 +-
 tests/qemu-iotests/common.rc                  |   6 +-
 tests/qemu-iotests/tests/fuse-allow-other     | 175 ++++++++++++++++++
 tests/qemu-iotests/tests/fuse-allow-other.out |  88 +++++++++
 7 files changed, 421 insertions(+), 28 deletions(-)
 create mode 100755 tests/qemu-iotests/tests/fuse-allow-other
 create mode 100644 tests/qemu-iotests/tests/fuse-allow-other.out

-- 
2.31.1