From: Eric Biggers <ebiggers@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>,
Amir Goldstein <amir73il@gmail.com>,
Richard Weinberger <richard@nod.at>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-fscrypt@vger.kernel.org,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Paul Lawrence <paullawrence@google.com>
Subject: Re: overlayfs vs. fscrypt
Date: Wed, 13 Mar 2019 12:43:14 -0700 [thread overview]
Message-ID: <20190313194313.GB10169@gmail.com> (raw)
In-Reply-To: <20190313191945.GT2217@ZenIV.linux.org.uk>
On Wed, Mar 13, 2019 at 07:19:46PM +0000, Al Viro wrote:
> On Wed, Mar 13, 2019 at 09:44:33AM -0700, Eric Biggers wrote:
>
> > > Just to make sure - you do realize that ban on multiple dentries refering
> > > to the same directory inode is *NOT* conditional upon those dentries being
> > > hashed, right?
> >
> > Isn't this handled by d_splice_alias() already, by moving the old dentry to the
> > new name?
>
> ... which means that if somebody without the key chdirs into subdirectory
> they only see by encrypted name and waits for proper owner to look it up,
> they suddenly see it by _un_encrypted name. Or does O_PATH open, for
> that matter, so exec permissions on that thing are not required.
Is there a real problem here? After the key is added, the filenames are
supposed to be shown in plaintext, not ciphertext. This is intrinsic to the
fact that we don't support both "views" at the same time. Either the directory
has the key or it does not.
If someone is using ciphertext view (e.g. doing a directory traversal)
concurrently with the key being added, that can certainly break things. But the
ciphertext view only allows a very restricted set of actions such as deleting
files. And if such actions are necessary, the system userspace is meant to be
designed in such a way that adding the key can't race with it.
- Eric
next prev parent reply other threads:[~2019-03-13 19:43 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-13 12:31 overlayfs vs. fscrypt Richard Weinberger
2019-03-13 12:36 ` Miklos Szeredi
2019-03-13 12:47 ` Richard Weinberger
2019-03-13 12:58 ` Miklos Szeredi
2019-03-13 13:00 ` Richard Weinberger
2019-03-13 13:24 ` Miklos Szeredi
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 15:36 ` 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 [this message]
2019-03-13 15:30 ` Eric Biggers
2019-03-13 20:33 ` Richard Weinberger
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 ` [PATCH 1/4] fscrypt: Implement FS_CFLG_OWN_D_OPS Richard Weinberger
2019-03-14 17:15 ` [PATCH 2/4] fscrypt: Export fscrypt_d_ops 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 ` [PATCH 4/4] ubifs: Implement new mount option, fscrypt_key_required Richard Weinberger
2019-03-14 17:49 ` Eric Biggers
2019-03-14 20:54 ` Richard Weinberger
2019-03-14 23:07 ` Theodore Ts'o
2019-03-15 7:48 ` Richard Weinberger
2019-03-15 13:51 ` Theodore Ts'o
2019-03-15 13:59 ` Richard Weinberger
2019-03-14 23:15 ` James Bottomley
2019-03-14 23:42 ` Theodore Ts'o
2019-03-14 23:55 ` James Bottomley
2019-03-13 15:01 ` overlayfs vs. fscrypt Eric Biggers
2019-03-13 16:11 ` Al Viro
2019-03-13 16:33 ` Eric Biggers
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