From: Eric Biggers <ebiggers@kernel.org>
To: Richard Weinberger <richard@nod.at>
Cc: linux-fscrypt@vger.kernel.org,
Satya Tangirala <satyat@google.com>,
"open list:ABI/API" <linux-api@vger.kernel.org>,
linux-f2fs-devel@lists.sourceforge.net, keyrings@vger.kernel.org,
linux-mtd@lists.infradead.org, linux-crypto@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-ext4@vger.kernel.org, Paul Crowley <paulcrowley@google.com>
Subject: Re: [RFC PATCH v3 07/18] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl
Date: Mon, 18 Mar 2019 16:08:31 -0700 [thread overview]
Message-ID: <20190318230830.GA40545@gmail.com> (raw)
In-Reply-To: <20190221184203.GB140206@gmail.com>
Hi Richard,
On Thu, Feb 21, 2019 at 10:42:03AM -0800, Eric Biggers wrote:
> On Thu, Feb 21, 2019 at 10:33:12AM +0100, Richard Weinberger wrote:
> > Eric,
> >
> > Am Donnerstag, 21. Februar 2019, 06:49:39 CET schrieb Eric Biggers:
> > > Hi Richard,
> > >
> > > On Thu, Feb 21, 2019 at 12:52:38AM +0100, Richard Weinberger wrote:
> > > > On Wed, Feb 20, 2019 at 7:55 AM Eric Biggers <ebiggers@kernel.org> wrote:
> > > > > +#define FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE \
> > > > > + (CONST_STRLEN("fscrypt-") + FIELD_SIZEOF(struct super_block, s_id))
> > > > > +
> > > > > +#define FSCRYPT_MK_DESCRIPTION_SIZE (2 * FSCRYPT_KEY_DESCRIPTOR_SIZE + 1)
> > > > > +
> > > > > +static void format_fs_keyring_description(
> > > > > + char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE],
> > > > > + const struct super_block *sb)
> > > > > +{
> > > > > + sprintf(description, "fscrypt-%s", sb->s_id);
> > > > > +}
> > > >
> > > > I fear ->s_id is not the right thing.
> > > > For filesystems such as ext4 ->s_id is the name of the backing block device,
> > > > so it is per filesysem instance unique.
> > > > But this is not guaranteed. For UBIFS ->s_id is just "ubifs", always.
> > > > So the names will clash.
> > > >
> > >
> > > What name do you suggest using for UBIFS filesystems? The keyring name could be
> > > set by the filesystem via a fscrypt_operations callback if needed.
> >
> > IMHO the BDI name should be used.
I tried using sb->s_bdi->name, but it's still "ubifs" for all UBIFS filesystems.
Perhaps there's a way you can make ->s_id for UBIFS unique? There are already
existing places that log ->s_id, so perhaps you should do it anyway regardless
of this patchset?
> >
> > > Note that the keyring name isn't particularly important, since the ioctls will
> > > work regardless. But we might as well choose something logical, since the
> > > keyring name will still show up in /proc/keys.
> >
> > I'm not done with reviewing your patches, but will it be possible to use keyctl?
> > For the a unique name is helpful. :)
> >
>
> Not for adding keys, removing keys, or getting a key's status -- those are what
> the ioctls are for.
>
> See e.g. the discussion in patch 7 ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY
> ioctl") for why the keyrings syscalls are a poor fit for fscrypt.
>
Anyway, perhaps I should reconsider whether fscrypt should even use the keyrings
subsystem at all, even just "internally", as its quirks still leak out a bit.
I'd prefer a nice clean API without any quirks like having to name the keyrings
and assign SELinux labels to the keys just to make the keyrings subsystem happy.
- Eric
next prev parent reply other threads:[~2019-03-18 23:08 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 6:52 [RFC PATCH v3 00/18] fscrypt: key management improvements Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 01/18] fs, fscrypt: move uapi definitions to new header <linux/fscrypt.h> Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 02/18] fscrypt: use FSCRYPT_ prefix for uapi constants Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 03/18] fscrypt: use FSCRYPT_* definitions, not FS_* Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 04/18] fs: add ->s_master_keys to struct super_block Eric Biggers
2019-02-20 23:19 ` Richard Weinberger
2019-02-20 6:52 ` [RFC PATCH v3 05/18] fscrypt: add ->ci_inode to fscrypt_info Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 06/18] fscrypt: refactor v1 policy key setup into keysetup_legacy.c Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 07/18] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl Eric Biggers
2019-02-20 23:52 ` Richard Weinberger
2019-02-21 5:49 ` Eric Biggers
2019-02-21 9:33 ` Richard Weinberger
2019-02-21 18:42 ` Eric Biggers
2019-03-18 23:08 ` Eric Biggers [this message]
2019-03-22 22:02 ` Richard Weinberger
2019-02-20 6:52 ` [RFC PATCH v3 08/18] fs/dcache.c: add shrink_dcache_inode() Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 09/18] fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 10/18] fscrypt: add FS_IOC_GET_ENCRYPTION_KEY_STATUS ioctl Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 11/18] fscrypt: add an HKDF-SHA512 implementation Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 12/18] fscrypt: v2 encryption policy support Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 13/18] fscrypt: allow unprivileged users to add/remove keys for v2 policies Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 14/18] fscrypt: require that key be added when setting a v2 encryption policy Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 15/18] ext4: wire up new fscrypt ioctls Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 16/18] f2fs: " Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 17/18] ubifs: " Eric Biggers
2019-02-20 6:52 ` [RFC PATCH v3 18/18] fscrypt: document the new ioctls and policy version Eric Biggers
2019-02-20 7:18 ` [RFC PATCH v3 00/18] fscrypt: key management improvements Andreas Dilger
2019-02-20 7:54 ` Eric Biggers
2019-02-20 18:07 ` David Howells
2019-02-20 18:36 ` Eric Biggers
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