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From: Eric Biggers <ebiggers@kernel.org>
To: Jeff Layton <jlayton@kernel.org>
Cc: ceph-devel@vger.kernel.org, linux-fscrypt@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH v3 14/16] ceph: add support to readdir for encrypted filenames
Date: Tue, 15 Sep 2020 13:40:18 -0700	[thread overview]
Message-ID: <20200915204018.GA3999121@gmail.com> (raw)
In-Reply-To: <bf448095f9d675bad3adb0ddc2d7652625824bc6.camel@kernel.org>

On Tue, Sep 15, 2020 at 09:27:49AM -0400, Jeff Layton wrote:
> > > +	}
> > > +
> > > +	declen = fscrypt_base64_decode(name, len, tname->name);
> > > +	if (declen < 0 || declen > NAME_MAX) {
> > > +		ret = -EIO;
> > > +		goto out;
> > > +	}
> > 
> > declen <= 0, to cover the empty name case.
> > 
> > Also, is there a point in checking for > NAME_MAX?
> > 
> 
> IDK. We're getting these strings from the MDS and they could end up
> being corrupt if there are bugs there (or if the MDS is compromised). 
> Of course, if we get a name longer than NAME_MAX then we've overrun the
> buffer.
> 
> Maybe we should add a maxlen parameter to fscrypt_base64_encode/decode ?
> Or maybe I should just have fscrypt_fname_alloc_buffer allocate a buffer
> the same size as "len"? It might be a little larger than necessary, but
> that would be safer.

How about checking that the base64-encoded filename is <= BASE64_CHARS(NAME_MAX)
in length?  Then decoding it can't give more than NAME_MAX bytes.

fscrypt_setup_filename() does a similar check when decoding a no-key name.

- Eric

  reply	other threads:[~2020-09-15 20:41 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 19:16 [RFC PATCH v3 00/16] ceph+fscrypt: context, filename and symlink support Jeff Layton
2020-09-14 19:16 ` [RFC PATCH v3 01/16] vfs: export new_inode_pseudo Jeff Layton
2020-09-14 23:33   ` Eric Biggers
2020-09-23  3:41   ` Al Viro
2020-09-23 11:19     ` Jeff Layton
2020-09-14 19:16 ` [RFC PATCH v3 02/16] fscrypt: export fscrypt_base64_encode and fscrypt_base64_decode Jeff Layton
2020-09-14 23:44   ` Eric Biggers
2020-09-14 19:16 ` [RFC PATCH v3 03/16] fscrypt: export fscrypt_d_revalidate Jeff Layton
2020-09-15  0:04   ` Eric Biggers
2020-09-14 19:16 ` [RFC PATCH v3 04/16] fscrypt: add fscrypt_context_for_new_inode Jeff Layton
2020-09-15  0:15   ` Eric Biggers
2020-09-14 19:16 ` [RFC PATCH v3 05/16] fscrypt: make fscrypt_fname_disk_to_usr return whether result is nokey name Jeff Layton
2020-09-15  0:23   ` Eric Biggers
2020-09-14 19:16 ` [RFC PATCH v3 06/16] ceph: add fscrypt ioctls Jeff Layton
2020-09-15  0:45   ` Eric Biggers
2020-09-15 12:08     ` Jeff Layton
2020-09-14 19:16 ` [RFC PATCH v3 07/16] ceph: crypto context handling for ceph Jeff Layton
2020-09-15  1:00   ` Eric Biggers
2020-09-14 19:16 ` [RFC PATCH v3 08/16] ceph: implement -o test_dummy_encryption mount option Jeff Layton
2020-09-15  1:23   ` Eric Biggers
2020-09-16 12:49     ` Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 09/16] ceph: preallocate inode for ops that may create one Jeff Layton
2020-09-15  1:30   ` Eric Biggers
2020-09-16 12:41     ` Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 10/16] ceph: add routine to create context prior to RPC Jeff Layton
2020-09-15  1:37   ` Eric Biggers
2020-09-16 12:18     ` Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 11/16] ceph: make ceph_msdc_build_path use ref-walk Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 12/16] ceph: add encrypted fname handling to ceph_mdsc_build_path Jeff Layton
2020-09-15  1:41   ` Eric Biggers
2020-09-16 12:30     ` Jeff Layton
2020-09-16 17:36       ` Eric Biggers
2020-09-16 18:04         ` Jeff Layton
2020-09-16 18:42           ` Eric Biggers
2020-09-14 19:17 ` [RFC PATCH v3 13/16] ceph: make d_revalidate call fscrypt revalidator for encrypted dentries Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 14/16] ceph: add support to readdir for encrypted filenames Jeff Layton
2020-09-15  1:57   ` Eric Biggers
2020-09-15 13:27     ` Jeff Layton
2020-09-15 20:40       ` Eric Biggers [this message]
2020-09-16 12:16         ` Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 15/16] ceph: add fscrypt support to ceph_fill_trace Jeff Layton
2020-09-14 19:17 ` [RFC PATCH v3 16/16] ceph: create symlinks with encrypted and base64-encoded targets Jeff Layton
2020-09-15  2:07   ` Eric Biggers
2020-09-15 14:05     ` Jeff Layton
2020-09-15 20:49       ` Eric Biggers
2020-09-16 12:15         ` Jeff Layton
2020-09-15  2:13 ` [RFC PATCH v3 00/16] ceph+fscrypt: context, filename and symlink support Eric Biggers
2020-09-15 13:38   ` Jeff Layton

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