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From: Eric Biggers <ebiggers@kernel.org>
To: Jeff Layton <jlayton@kernel.org>
Cc: linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-mtd@lists.infradead.org, ceph-devel@vger.kernel.org,
	Daniel Rosenberg <drosen@google.com>
Subject: Re: [PATCH v3 13/13] fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *'
Date: Thu, 17 Sep 2020 08:29:07 -0700	[thread overview]
Message-ID: <20200917152907.GB855@sol.localdomain> (raw)
In-Reply-To: <41ad3cd50f4d213455bef4e7c42143c289690222.camel@kernel.org>

On Thu, Sep 17, 2020 at 08:32:39AM -0400, Jeff Layton wrote:
> On Wed, 2020-09-16 at 21:11 -0700, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > fscrypt_set_test_dummy_encryption() requires that the optional argument
> > to the test_dummy_encryption mount option be specified as a substring_t.
> > That doesn't work well with filesystems that use the new mount API,
> > since the new way of parsing mount options doesn't use substring_t.
> > 
> > Make it take the argument as a 'const char *' instead.
> > 
> > Instead of moving the match_strdup() into the callers in ext4 and f2fs,
> > make them just use arg->from directly.  Since the pattern is
> > "test_dummy_encryption=%s", the argument will be null-terminated.
> > 
> 
> Are you sure about that? I thought the point of substring_t was to give
> you a token from the string without null terminating it.
> 
> ISTM that when you just pass in ->from, you might end up with trailing
> arguments in your string like this. e.g.:
> 
>     "v2,foo,bar,baz"
> 
> ...and then that might fail to match properly
> in fscrypt_set_test_dummy_encryption.
> 

Yes I'm sure, and I had also tested it.  The use of match_token() here is to
parse one null-terminated mount option at a time.

The reason that match_token() can return multiple substrings is that the pattern
might be something like "foo=%d:%d".

But here it's just "test_dummy_encryption=%s". "%s" matches until end-of-string.

- Eric

  reply	other threads:[~2020-09-17 15:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-17  4:11 [PATCH v3 00/13] fscrypt: improve file creation flow Eric Biggers
2020-09-17  4:11 ` [PATCH v3 01/13] fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context() Eric Biggers
2020-09-17  4:11 ` [PATCH v3 02/13] ext4: factor out ext4_xattr_credits_for_new_inode() Eric Biggers
2020-09-17  4:11 ` [PATCH v3 03/13] ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context() Eric Biggers
2020-09-17  4:11 ` [PATCH v3 04/13] f2fs: " Eric Biggers
2020-09-17  4:11 ` [PATCH v3 05/13] ubifs: " Eric Biggers
2020-09-17  4:11 ` [PATCH v3 06/13] fscrypt: adjust logging for in-creation inodes Eric Biggers
2020-09-17  4:11 ` [PATCH v3 07/13] fscrypt: remove fscrypt_inherit_context() Eric Biggers
2020-09-17  4:11 ` [PATCH v3 08/13] fscrypt: require that fscrypt_encrypt_symlink() already has key Eric Biggers
2020-09-17  4:11 ` [PATCH v3 09/13] fscrypt: stop pretending that key setup is nofs-safe Eric Biggers
2020-09-17  4:11 ` [PATCH v3 10/13] fscrypt: make "#define fscrypt_policy" user-only Eric Biggers
2020-09-17  4:11 ` [PATCH v3 11/13] fscrypt: move fscrypt_prepare_symlink() out-of-line Eric Biggers
2020-09-17  4:11 ` [PATCH v3 12/13] fscrypt: handle test_dummy_encryption in more logical way Eric Biggers
2020-09-17  4:11 ` [PATCH v3 13/13] fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *' Eric Biggers
2020-09-17 12:32   ` Jeff Layton
2020-09-17 15:29     ` Eric Biggers [this message]
2020-09-17 16:33       ` Jeff Layton
2020-09-21 22:35 ` [PATCH v3 00/13] fscrypt: improve file creation flow Eric Biggers
2020-09-22 11:29   ` Jeff Layton
2020-09-22 13:50     ` Eric Biggers

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