From: James Bottomley <James.Bottomley@HansenPartnership.com> To: Theodore Ts'o <tytso@mit.edu> Cc: Richard Weinberger <richard@nod.at>, linux-mtd@lists.infradead.org, linux-fscrypt@vger.kernel.org, jaegeuk@kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, paullawrence@google.com Subject: Re: [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Date: Thu, 14 Mar 2019 16:55:40 -0700 [thread overview] Message-ID: <1552607740.2571.15.camel@HansenPartnership.com> (raw) In-Reply-To: <20190314234230.GG6482@mit.edu> On Thu, 2019-03-14 at 19:42 -0400, Theodore Ts'o wrote: > On Thu, Mar 14, 2019 at 04:15:11PM -0700, James Bottomley wrote: > > On Thu, 2019-03-14 at 18:15 +0100, Richard Weinberger wrote: > > > Usually fscrypt allows limited access to encrypted files even > > > if no key is available. > > > Encrypted filenames are shown and based on this names users > > > can unlink and move files. > > > > Shouldn't they be able to read/write and create as well (all with > > the ciphertext name and contents, of course) ... otherwise how does > > backup of encrypted files by admin without the key ever work? > > That's not currently supported. Michael Halcrow and I worked out > some designs on how to do this, and I even had some prototype > patches, but it's really, really, messy, and requires a lot of > complex machinations in userspace on the save *and* restore, since > there's a lot of crypto metadata that has to be saved, and you have > to handle backing up the directory per-file keys, and restoring them > when you recreate the directory on a restore, etc. > > The simpler approach would have allowed backup of encrypted files > without the key, but would require the user's key to do the restore, > and if we ever actually tried to get this feature supported, that's > the approach I'd suggest. Well, as I said above encrypted file backup by an admin who doesn't have the key was what I was thinking of. > The fundamental reason why we never went did anything with this was > that the original use case of fscrypt was for Chrome OS, where the > original design premise was that you don't need to do backups, since > everything is in the cloud. A video from 2010: > > https://www.youtube.com/watch?v=lm-Vnx58UYo > > And with Android, backups happen automatically while you have the > encryption key. Heh, colour me paranoid, but if I backup my sensitive data to any medium (including the cloud) I *want* the backup to be encrypted so that if someone is careless with my backup data at least they don't get the contents. > There was talk about using fscrypt for Ubuntu desktops as an ecryptfs > replacement, and in that case, we would have use case that would have > required backups of a shared desktop where you don't have all of the > encryption keys for all of the users. Maybe someday as a Google > Summer of Code project or maybe if some potential corporate user of > fscrypt would be willing to fund the necessary engineering work? > > But again, I'll repeat this because it's so important: In the vast > majority of cases, including single-user laptops, desktops, etc., the > real right answer is dm-crypt and *not* fscrypt. Especially since > time-sharing systems are *so* 1980's. :-) > > So I don't use fscrypt on my upstream development laptop (except for > testing purposes) because it's simply not the right tool for the job. I was thinking of the container use case again. It's not really backup per se but it is serialization: if you can't do a backup ... i.e. save and restore an encrypted tar image, you can't use the filesystem for container image protection. But it also strikes me that inability to do backup and restore without the key really restricts the use cases for the entire filesystem. James
WARNING: multiple messages have this Message-ID (diff)
From: James Bottomley <James.Bottomley@HansenPartnership.com> To: Theodore Ts'o <tytso@mit.edu> Cc: miklos@szeredi.hu, Richard Weinberger <richard@nod.at>, amir73il@gmail.com, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, paullawrence@google.com, linux-fscrypt@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org Subject: Re: [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Date: Thu, 14 Mar 2019 16:55:40 -0700 [thread overview] Message-ID: <1552607740.2571.15.camel@HansenPartnership.com> (raw) In-Reply-To: <20190314234230.GG6482@mit.edu> On Thu, 2019-03-14 at 19:42 -0400, Theodore Ts'o wrote: > On Thu, Mar 14, 2019 at 04:15:11PM -0700, James Bottomley wrote: > > On Thu, 2019-03-14 at 18:15 +0100, Richard Weinberger wrote: > > > Usually fscrypt allows limited access to encrypted files even > > > if no key is available. > > > Encrypted filenames are shown and based on this names users > > > can unlink and move files. > > > > Shouldn't they be able to read/write and create as well (all with > > the ciphertext name and contents, of course) ... otherwise how does > > backup of encrypted files by admin without the key ever work? > > That's not currently supported. Michael Halcrow and I worked out > some designs on how to do this, and I even had some prototype > patches, but it's really, really, messy, and requires a lot of > complex machinations in userspace on the save *and* restore, since > there's a lot of crypto metadata that has to be saved, and you have > to handle backing up the directory per-file keys, and restoring them > when you recreate the directory on a restore, etc. > > The simpler approach would have allowed backup of encrypted files > without the key, but would require the user's key to do the restore, > and if we ever actually tried to get this feature supported, that's > the approach I'd suggest. Well, as I said above encrypted file backup by an admin who doesn't have the key was what I was thinking of. > The fundamental reason why we never went did anything with this was > that the original use case of fscrypt was for Chrome OS, where the > original design premise was that you don't need to do backups, since > everything is in the cloud. A video from 2010: > > https://www.youtube.com/watch?v=lm-Vnx58UYo > > And with Android, backups happen automatically while you have the > encryption key. Heh, colour me paranoid, but if I backup my sensitive data to any medium (including the cloud) I *want* the backup to be encrypted so that if someone is careless with my backup data at least they don't get the contents. > There was talk about using fscrypt for Ubuntu desktops as an ecryptfs > replacement, and in that case, we would have use case that would have > required backups of a shared desktop where you don't have all of the > encryption keys for all of the users. Maybe someday as a Google > Summer of Code project or maybe if some potential corporate user of > fscrypt would be willing to fund the necessary engineering work? > > But again, I'll repeat this because it's so important: In the vast > majority of cases, including single-user laptops, desktops, etc., the > real right answer is dm-crypt and *not* fscrypt. Especially since > time-sharing systems are *so* 1980's. :-) > > So I don't use fscrypt on my upstream development laptop (except for > testing purposes) because it's simply not the right tool for the job. I was thinking of the container use case again. It's not really backup per se but it is serialization: if you can't do a backup ... i.e. save and restore an encrypted tar image, you can't use the filesystem for container image protection. But it also strikes me that inability to do backup and restore without the key really restricts the use cases for the entire filesystem. James ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2019-03-14 23:55 UTC|newest] Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-13 12:31 overlayfs vs. fscrypt Richard Weinberger 2019-03-13 12:31 ` Richard Weinberger 2019-03-13 12:36 ` Miklos Szeredi 2019-03-13 12:47 ` Richard Weinberger 2019-03-13 12:47 ` Richard Weinberger 2019-03-13 12:58 ` Miklos Szeredi 2019-03-13 13:00 ` Richard Weinberger 2019-03-13 13:00 ` Richard Weinberger 2019-03-13 13:24 ` Miklos Szeredi 2019-03-13 13:32 ` Richard Weinberger 2019-03-13 13:32 ` Richard Weinberger 2019-03-13 14:26 ` Amir Goldstein 2019-03-13 15:16 ` Theodore Ts'o 2019-03-13 15:30 ` Richard Weinberger 2019-03-13 15:30 ` Richard Weinberger 2019-03-13 15:36 ` James Bottomley 2019-03-13 15:51 ` Eric Biggers 2019-03-13 16:13 ` James Bottomley 2019-03-13 16:24 ` Richard Weinberger 2019-03-13 16:44 ` Theodore Ts'o 2019-03-13 17:45 ` James Bottomley 2019-03-13 18:58 ` Theodore Ts'o 2019-03-13 19:17 ` James Bottomley 2019-03-13 19:57 ` Eric Biggers 2019-03-13 20:06 ` James Bottomley 2019-03-13 20:25 ` Eric Biggers 2019-03-13 21:04 ` James Bottomley 2019-03-13 22:13 ` Eric Biggers 2019-03-13 22:29 ` James Bottomley 2019-03-13 22:58 ` Eric Biggers 2019-03-13 16:06 ` Al Viro 2019-03-13 16:44 ` Eric Biggers 2019-03-13 19:19 ` Al Viro 2019-03-13 19:43 ` Eric Biggers 2019-03-13 15:30 ` Eric Biggers 2019-03-13 15:30 ` Eric Biggers 2019-03-13 20:33 ` Richard Weinberger 2019-03-13 20:33 ` Richard Weinberger 2019-03-13 22:26 ` Eric Biggers 2019-03-13 22:26 ` Eric Biggers 2019-03-13 22:42 ` Richard Weinberger 2019-03-14 7:34 ` Miklos Szeredi 2019-03-14 17:15 ` [RFC] fscrypt_key_required mount option Richard Weinberger 2019-03-14 17:15 ` Richard Weinberger 2019-03-14 17:15 ` [PATCH 1/4] fscrypt: Implement FS_CFLG_OWN_D_OPS Richard Weinberger 2019-03-14 17:15 ` Richard Weinberger 2019-03-14 17:15 ` [PATCH 2/4] fscrypt: Export fscrypt_d_ops Richard Weinberger 2019-03-14 17:15 ` Richard Weinberger 2019-03-14 17:15 ` [PATCH 3/4] ubifs: Simplify fscrypt_get_encryption_info() error handling Richard Weinberger 2019-03-14 17:15 ` Richard Weinberger 2019-03-14 17:15 ` [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Richard Weinberger 2019-03-14 17:15 ` Richard Weinberger 2019-03-14 17:49 ` Eric Biggers 2019-03-14 17:49 ` Eric Biggers 2019-03-14 20:54 ` Richard Weinberger 2019-03-14 20:54 ` Richard Weinberger 2019-03-14 23:07 ` Theodore Ts'o 2019-03-14 23:07 ` Theodore Ts'o 2019-03-15 0:26 ` Unsubscribe Shane Volpe 2019-03-15 7:48 ` [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Richard Weinberger 2019-03-15 7:48 ` Richard Weinberger 2019-03-15 13:51 ` Theodore Ts'o 2019-03-15 13:51 ` Theodore Ts'o 2019-03-15 13:51 ` Theodore Ts'o 2019-03-15 13:59 ` Richard Weinberger 2019-03-15 13:59 ` Richard Weinberger 2019-03-14 23:15 ` James Bottomley 2019-03-14 23:15 ` James Bottomley 2019-03-14 23:42 ` Theodore Ts'o 2019-03-14 23:42 ` Theodore Ts'o 2019-03-14 23:55 ` James Bottomley [this message] 2019-03-14 23:55 ` James Bottomley 2019-03-13 15:01 ` overlayfs vs. fscrypt Eric Biggers 2019-03-13 15:01 ` Eric Biggers 2019-03-13 16:11 ` Al Viro 2019-03-13 16:33 ` Eric Biggers
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1552607740.2571.15.camel@HansenPartnership.com \ --to=james.bottomley@hansenpartnership.com \ --cc=amir73il@gmail.com \ --cc=jaegeuk@kernel.org \ --cc=linux-fscrypt@vger.kernel.org \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mtd@lists.infradead.org \ --cc=linux-unionfs@vger.kernel.org \ --cc=miklos@szeredi.hu \ --cc=paullawrence@google.com \ --cc=richard@nod.at \ --cc=tytso@mit.edu \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.