From: ebiederm@xmission.com (Eric W. Biederman)
To: Miklos Szeredi <mszeredi@redhat.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
Linux Containers <containers@lists.linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Alban Crequy <alban@kinvolk.io>,
Seth Forshee <seth.forshee@canonical.com>,
Sargun Dhillon <sargun@sargun.me>,
Dongsu Park <dongsu@kinvolk.io>,
"Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH v9 0/4] fuse: mounts from non-init user namespaces
Date: Tue, 20 Mar 2018 13:27:57 -0500 [thread overview]
Message-ID: <87tvta38lu.fsf@xmission.com> (raw)
In-Reply-To: <CAOssrKebhX-nm06RAwep8HUUV4QpsAa=ZOgxdRyP=WF9p-=4Tw@mail.gmail.com> (Miklos Szeredi's message of "Tue, 20 Mar 2018 17:25:06 +0100")
Miklos Szeredi <mszeredi@redhat.com> writes:
> On Thu, Mar 8, 2018 at 10:23 PM, Eric W. Biederman
> <ebiederm@xmission.com> wrote:
>>
>> This patchset builds on the work by Donsu Park and Seth Forshee and is
>> reduced to the set of patches that just affect fuse. The non-fuse
>> vfs patches are far enough along we can ignore them except possibly for the
>> question of when does FS_USERNS_MOUNT get set in fuse_fs_type.
>>
>> Fuse with a block device has been left as an exercise for a later time.
>>
>> Since v5 I changed the core of this patchset around as the previous
>> patches were showing signs of bitrot. Some important explanations were
>> missing, some important functionality was missing, and xattr handling
>> was completely absent.
>>
>> Since v6 I have:
>> - Removed the failure case from fuse_get_req_nofail_nopages that I
>> added.
>> - Updated fuse to always to use posix_acl_access_xattr_handler, and
>> posix_acl_default_xattr_handler, by teaching fuse to set
>> ACL_DONT_CACHE when FUSE_POSIX_ACL is not set.
>>
>> Since v7 I have:
>> - Rethought and reworked how I am unifying the cached and the non-cached
>> posix acl case so the code is cleaner and simpler.
>> - I have dropped enhancements to caching negative acls when
>> fc->no_getxattr is set.
>> - Removed the need to wrap forget_all_cached_acls in fuse.
>> - Reorder the patches so the posix acl work comes first
>>
>> Since v8 I have:
>> - Dropped and postponed the unification of the uncached and the cached
>> posix acls case. The code is not hard but tricky enough it needs
>> to be considered on it's own on it's own merits.
>>
>> Miklos can you take a look and see what you think?
>>
>> Miklos if you could pick these up I would appreciate it. If not I can
>> merge these through the userns tree.
>
> Thank you Eric for moving this along. Patches pushed to:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git for-next
>
> I did just one modification to "fuse: Fail all requests with invalid
> uids or gids": instead of zeroing out the context for the nofail case,
> continue to use the "_munged" variants. I don't think this hurts and
> is better for backward compatibility (I guess the only relevant use
> would be for debugging output, but we don't want to regress even for
> that if not necessary)
Hmm...
The thing is the failure doesn't come in the difference between the
_munged and the normal variants. The difference between
munged and non-munged variants is how they handled failure ((uid16_t)-2)
aka 0xfffe for munged and -1 for the non-munged case.
The failures are introduced by changing &init_user_ns to fc->user_ns.
The operations in question are iop->flush and fuse_force_forget (on an
error). I don't know what value having ids on those paths will do
they are operations that must succeed, and they should not change the
on-disk ids. I was thinking saying the most privileged id was asking
for the oepration would seem to make sense.
With the munged variants we will get (uid16_t)-2 aka 0xfffe aka
nobody asking for the operation if things don't map. In practice
the don't map case is new.
Since the id's should not be looked at anyway I don't see it makes
much difference which ids we use so the munged case seems at least
plausible.
It might be better to use the non-munghed variant and do:
if (req->in.h.uid == (uid_t)-1)
req.in.h.uid = 0;
if (req->in.h.gid == (gid_t)-1)
req.in.h.gid = 0;
That might be less surprising to userspace. As I don't think the
unmapped case has ever occurred in practice yet. The vfs will work hard
to keep the unmapped case from happening but only in the context of
i_uid and i_gid not current_fsuid and current_fsgid.
Eric
next prev parent reply other threads:[~2018-03-20 18:28 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-22 14:32 [PATCH v5 00/11] FUSE mounts from non-init user namespaces Dongsu Park
2017-12-22 14:32 ` [PATCH 01/11] block_dev: Support checking inode permissions in lookup_bdev() Dongsu Park
2017-12-22 18:59 ` Coly Li
2017-12-23 12:00 ` Dongsu Park
2017-12-23 3:03 ` Serge E. Hallyn
2017-12-22 14:32 ` [PATCH 02/11] mtd: Check permissions towards mtd block device inode when mounting Dongsu Park
2017-12-22 21:06 ` Richard Weinberger
2017-12-23 12:18 ` Dongsu Park
2017-12-23 12:56 ` Richard Weinberger
2017-12-23 3:05 ` Serge E. Hallyn
2017-12-22 14:32 ` [PATCH 03/11] fs: Allow superblock owner to change ownership of inodes Dongsu Park
2017-12-23 3:17 ` Serge E. Hallyn
2018-01-05 19:24 ` Luis R. Rodriguez
2018-01-09 15:10 ` Dongsu Park
2018-01-09 17:23 ` Luis R. Rodriguez
2018-02-13 13:18 ` Miklos Szeredi
2018-02-16 22:00 ` Eric W. Biederman
2017-12-22 14:32 ` [PATCH 04/11] fs: Don't remove suid for CAP_FSETID for userns root Dongsu Park
2017-12-23 3:26 ` Serge E. Hallyn
2017-12-23 12:38 ` Dongsu Park
2018-02-13 13:37 ` Miklos Szeredi
2017-12-22 14:32 ` [PATCH 05/11] fs: Allow superblock owner to access do_remount_sb() Dongsu Park
2017-12-23 3:30 ` Serge E. Hallyn
2017-12-22 14:32 ` [PATCH 06/11] capabilities: Allow privileged user in s_user_ns to set security.* xattrs Dongsu Park
2017-12-23 3:33 ` Serge E. Hallyn
2017-12-22 14:32 ` [PATCH 07/11] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems Dongsu Park
2017-12-23 3:39 ` Serge E. Hallyn
2018-02-14 12:28 ` Miklos Szeredi
2018-02-19 22:56 ` Eric W. Biederman
2017-12-22 14:32 ` [PATCH 08/11] fuse: Support fuse filesystems outside of init_user_ns Dongsu Park
2017-12-23 3:46 ` Serge E. Hallyn
2018-01-17 10:59 ` Alban Crequy
2018-01-17 14:29 ` Seth Forshee
2018-01-17 18:56 ` Alban Crequy
2018-01-17 19:31 ` Seth Forshee
2018-01-18 10:29 ` Alban Crequy
2018-02-12 15:57 ` Miklos Szeredi
2018-02-12 16:35 ` Eric W. Biederman
2018-02-13 10:20 ` Miklos Szeredi
2018-02-16 21:52 ` Eric W. Biederman
2018-02-20 2:12 ` Eric W. Biederman
2017-12-22 14:32 ` [PATCH 09/11] fuse: Restrict allow_other to the superblock's namespace or a descendant Dongsu Park
2017-12-23 3:50 ` Serge E. Hallyn
2018-02-19 23:16 ` Eric W. Biederman
2017-12-22 14:32 ` [PATCH 10/11] fuse: Allow user namespace mounts Dongsu Park
2017-12-23 3:51 ` Serge E. Hallyn
2018-02-14 13:44 ` Miklos Szeredi
2018-02-15 8:46 ` Miklos Szeredi
2017-12-22 14:32 ` [PATCH 11/11] evm: Don't update hmacs in user ns mounts Dongsu Park
2017-12-23 4:03 ` Serge E. Hallyn
2017-12-24 5:12 ` Mimi Zohar
2017-12-24 5:56 ` Mimi Zohar
2017-12-25 7:05 ` [PATCH v5 00/11] FUSE mounts from non-init user namespaces Eric W. Biederman
2018-01-09 15:05 ` Dongsu Park
2018-01-18 14:58 ` Alban Crequy
2018-02-19 23:09 ` Eric W. Biederman
2018-02-13 11:32 ` Miklos Szeredi
2018-02-16 21:53 ` Eric W. Biederman
2018-02-21 20:24 ` [PATCH v6 0/6] fuse: " Eric W. Biederman
2018-02-21 20:29 ` [PATCH v6 1/5] fuse: Remove the buggy retranslation of pids in fuse_dev_do_read Eric W. Biederman
2018-02-22 10:13 ` Miklos Szeredi
2018-02-22 19:04 ` Eric W. Biederman
2018-02-21 20:29 ` [PATCH v6 2/5] fuse: Fail all requests with invalid uids or gids Eric W. Biederman
2018-02-22 10:26 ` Miklos Szeredi
2018-02-22 18:15 ` Eric W. Biederman
2018-02-21 20:29 ` [PATCH v6 3/5] fuse: Support fuse filesystems outside of init_user_ns Eric W. Biederman
2018-02-21 20:29 ` [PATCH v6 4/5] fuse: Ensure posix acls are translated " Eric W. Biederman
2018-02-22 11:40 ` Miklos Szeredi
2018-02-22 19:18 ` Eric W. Biederman
2018-02-22 22:50 ` Eric W. Biederman
2018-02-26 7:47 ` Miklos Szeredi
2018-02-26 16:35 ` Eric W. Biederman
2018-02-26 21:51 ` Eric W. Biederman
2018-02-21 20:29 ` [PATCH v6 5/5] fuse: Restrict allow_other to the superblock's namespace or a descendant Eric W. Biederman
2018-02-26 23:52 ` [PATCH v7 0/7] fuse: mounts from non-init user namespaces Eric W. Biederman
2018-02-26 23:52 ` [PATCH v7 1/7] fuse: Remove the buggy retranslation of pids in fuse_dev_do_read Eric W. Biederman
2018-02-26 23:52 ` [PATCH v7 2/7] fuse: Fail all requests with invalid uids or gids Eric W. Biederman
2018-02-26 23:52 ` [PATCH v7 3/7] fs/posix_acl: Document that get_acl respects ACL_DONT_CACHE Eric W. Biederman
2018-02-27 1:13 ` Linus Torvalds
2018-02-27 2:53 ` Eric W. Biederman
2018-02-27 3:14 ` Eric W. Biederman
2018-02-27 3:41 ` Linus Torvalds
2018-03-02 19:53 ` [RFC][PATCH] fs/posix_acl: Update the comments and support lightweight cache skipping Eric W. Biederman
2018-02-27 3:36 ` [PATCH v7 3/7] fs/posix_acl: Document that get_acl respects ACL_DONT_CACHE Linus Torvalds
2018-02-26 23:52 ` [PATCH v7 4/7] fuse: Cache a NULL acl when FUSE_GETXATTR returns -ENOSYS Eric W. Biederman
2018-02-26 23:53 ` [PATCH v7 5/7] fuse: Simplfiy the posix acl handling logic Eric W. Biederman
2018-02-27 9:00 ` Miklos Szeredi
2018-03-02 21:49 ` Eric W. Biederman
2018-02-26 23:53 ` [PATCH v7 6/7] fuse: Support fuse filesystems outside of init_user_ns Eric W. Biederman
2018-02-26 23:53 ` [PATCH v7 7/7] fuse: Restrict allow_other to the superblock's namespace or a descendant Eric W. Biederman
2018-03-02 21:58 ` [PATCH v8 0/6] fuse: mounts from non-init user namespaces Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 1/6] fs/posix_acl: Update the comments and support lightweight cache skipping Eric W. Biederman
2018-03-05 9:53 ` Miklos Szeredi
2018-03-05 13:53 ` Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 2/6] fuse: Simplfiy the posix acl handling logic Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 3/6] fuse: Remove the buggy retranslation of pids in fuse_dev_do_read Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 4/6] fuse: Fail all requests with invalid uids or gids Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 5/6] fuse: Support fuse filesystems outside of init_user_ns Eric W. Biederman
2018-03-02 21:59 ` [PATCH v8 6/6] fuse: Restrict allow_other to the superblock's namespace or a descendant Eric W. Biederman
2018-03-08 21:23 ` [PATCH v9 0/4] fuse: mounts from non-init user namespaces Eric W. Biederman
2018-03-08 21:24 ` [PATCH v9 1/4] fuse: Remove the buggy retranslation of pids in fuse_dev_do_read Eric W. Biederman
2018-03-08 21:24 ` [PATCH v9 2/4] fuse: Fail all requests with invalid uids or gids Eric W. Biederman
2018-03-08 21:24 ` [PATCH v9 3/4] fuse: Support fuse filesystems outside of init_user_ns Eric W. Biederman
2018-03-08 21:24 ` [PATCH v9 4/4] fuse: Restrict allow_other to the superblock's namespace or a descendant Eric W. Biederman
2018-03-20 16:25 ` [PATCH v9 0/4] fuse: mounts from non-init user namespaces Miklos Szeredi
2018-03-20 18:27 ` Eric W. Biederman [this message]
2018-03-21 8:38 ` Miklos Szeredi
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