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From: Eric Biggers <ebiggers@kernel.org>
To: Jeff Layton <jlayton@kernel.org>
Cc: Luis Henriques <lhenriques@suse.de>,
	ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-fscrypt@vger.kernel.org
Subject: Re: [RFC PATCH v6 20/20] ceph: add fscrypt ioctls
Date: Mon, 19 Apr 2021 12:54:17 -0700
Message-ID: <YH3f6YQ7cxWCVb+b@gmail.com> (raw)
In-Reply-To: <f6fa8d02d31099a688ae97450143aa0eed4b73f8.camel@kernel.org>

On Mon, Apr 19, 2021 at 08:19:59AM -0400, Jeff Layton wrote:
> On Mon, 2021-04-19 at 11:09 +0100, Luis Henriques wrote:
> > Hi Jeff!
> > 
> > Jeff Layton <jlayton@kernel.org> writes:
> > <...>
> > > +
> > > +	case FS_IOC_ADD_ENCRYPTION_KEY:
> > > +		ret = vet_mds_for_fscrypt(file);
> > > +		if (ret)
> > > +			return ret;
> > > +		atomic_inc(&ci->i_shared_gen);
> > 
> > After spending some (well... a lot, actually) time looking at the MDS code
> > to try to figure out my bug, I'm back at this point in the kernel client
> > code.  I understand that this code is trying to invalidate the directory
> > dentries here.  However, I just found that the directory we get at this
> > point is the filesystem root directory, and not the directory we're trying
> > to unlock.
> > 
> > So, I still don't fully understand the issue I'm seeing, but I believe the
> > code above is assuming 'ci' is the inode being unlocked, which isn't
> > correct.
> > 
> > (Note: I haven't checked if there are other ioctls getting the FS root.)
> > 
> > Cheers,
> 
> 
> Oh, interesting. That was my assumption. I'll have to take a look more
> closely at what effect that might have then.
> 

FS_IOC_ADD_ENCRYPTION_KEY, FS_IOC_REMOVE_ENCRYPTION_KEY,
FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS, and FS_IOC_GET_ENCRYPTION_KEY_STATUS can
all be executed on any file or directory on the filesystem (but preferably on
the root directory) because they are operations on the filesystem, not on any
specific file or directory.  They deal with encryption keys, which can protect
any number of encrypted directories (even 0 or a large number) and/or even loose
encrypted files that got moved into an unencrypted directory.

Note that this is all described in the documentation
(https://www.kernel.org/doc/html/latest/filesystems/fscrypt.html).
If the documentation is unclear please suggest improvements to it.

Also, there shouldn't be any need for FS_IOC_ADD_ENCRYPTION_KEY to invalidate
dentries itself because that is the point of fscrypt_d_revalidate(); the
invalidation happens on-demand later.

- Eric

  reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 17:50 [RFC PATCH v6 00/20] ceph+fscrypt: context, filename and symlink support Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 01/20] vfs: export new_inode_pseudo Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 02/20] fscrypt: export fscrypt_base64_encode and fscrypt_base64_decode Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 03/20] fscrypt: export fscrypt_fname_encrypt and fscrypt_fname_encrypted_size Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 04/20] fscrypt: add fscrypt_context_for_new_inode Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 05/20] ceph: crypto context handling for ceph Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 06/20] ceph: implement -o test_dummy_encryption mount option Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 07/20] ceph: preallocate inode for ops that may create one Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 08/20] ceph: add routine to create fscrypt context prior to RPC Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 09/20] ceph: make ceph_msdc_build_path use ref-walk Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 10/20] ceph: add encrypted fname handling to ceph_mdsc_build_path Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 11/20] ceph: decode alternate_name in lease info Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 12/20] ceph: send altname in MClientRequest Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 13/20] ceph: properly set DCACHE_NOKEY_NAME flag in lookup Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 14/20] ceph: make d_revalidate call fscrypt revalidator for encrypted dentries Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 15/20] ceph: add helpers for converting names for userland presentation Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 16/20] ceph: add fscrypt support to ceph_fill_trace Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 17/20] ceph: add support to readdir for encrypted filenames Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 18/20] ceph: create symlinks with encrypted and base64-encoded targets Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 19/20] ceph: make ceph_get_name decrypt filenames Jeff Layton
2021-04-13 17:50 ` [RFC PATCH v6 20/20] ceph: add fscrypt ioctls Jeff Layton
2021-04-19 10:09   ` Luis Henriques
2021-04-19 12:19     ` Jeff Layton
2021-04-19 19:54       ` Eric Biggers [this message]
2021-04-20  9:34         ` Luis Henriques
2021-04-20 11:45         ` Jeff Layton
2021-04-19 10:30 ` [RFC PATCH v6 00/20] ceph+fscrypt: context, filename and symlink support Luis Henriques
2021-04-19 12:23   ` Jeff Layton
2021-04-19 16:03     ` Luis Henriques
2021-04-19 16:28       ` Jeff Layton
2021-04-20 10:11         ` Luis Henriques
2021-04-20 15:52           ` Jeff Layton

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