Linux-Modules Archive on lore.kernel.org
 help / Atom feed
From: "Luis R. Rodriguez" <mcgrof@suse.com>
To: Kees Cook <keescook@chromium.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux-modules@vger.kernel.org,
	"linux-fsdevel@vger.kernel.org" <fsdevel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>
Subject: Re: [PATCH v3 06/22] firmware: fold successful fw read early
Date: Thu, 4 Feb 2016 21:26:22 +0100
Message-ID: <20160204202622.GH12481@wotan.suse.de> (raw)
In-Reply-To: <CAGXu5j+=4gWSuQHX-iBVGZTsL3UFsLFp74+QeVNcSJHyK+4v8w@mail.gmail.com>

On Thu, Feb 04, 2016 at 09:36:50AM -0800, Kees Cook wrote:
> On Wed, Feb 3, 2016 at 11:06 AM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > From: David Howells <dhowells@redhat.com>
> >
> > We'll be folding in some more checks on fw_read_file_contents(),
> > this will make the success case easier to follow.
> >
> > Reviewed-by: Josh Boyer <jwboyer@fedoraproject.org>
> > Signed-off-by: David Howells <dhowells@redhat.com>
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > ---
> >  drivers/base/firmware_class.c | 16 +++++++---------
> >  1 file changed, 7 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index fb64814..c658cec 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -361,20 +361,18 @@ static int fw_get_filesystem_firmware(struct device *device,
> >                         continue;
> >                 rc = fw_read_file_contents(file, buf);
> >                 fput(file);
> > -               if (rc)
> > +               if (rc == 0) {
> > +                       dev_dbg(device, "direct-loading %s\n",
> > +                               buf->fw_id);
> > +                       fw_finish_direct_load(device, buf);
> > +                       goto out;
> > +               } else
> >                         dev_warn(device, "loading %s failed with error %d\n",
> >                                  path, rc);
> > -               else
> > -                       break;
> >         }
> > +out:
> >         __putname(path);
> >
> > -       if (!rc) {
> > -               dev_dbg(device, "direct-loading %s\n",
> > -                       buf->fw_id);
> > -               fw_finish_direct_load(device, buf);
> > -       }
> > -
> >         return rc;
> >  }
> 
> Looking at this code, why does this use "break":
> 
>                 len = snprintf(path, PATH_MAX, "%s/%s",
>                                fw_path[i], buf->fw_id);
>                 if (len >= PATH_MAX) {
>                         rc = -ENAMETOOLONG;
>                         break;
>                 }
> 
> Shouldn't that emit a warning, set rc, and continue?

Yes but this is a separate piece of code, and that's a functional change but I
welcome the change for sure.  This could be done separately.

> Regardless, I think this is more readable. Adding an "out" target at
> the end of a for loop seems weird, given "break" existing. :)

Good call, goto mixed with while loops can be get iffy.  I'm fine with this
change as a replacement. To be fair we should also note both patches (the one
submitted and yours below) also make a small functional change so that the loop
continues over all other possible directories in the fw_path in case of failure
with the first directory used as a base. If we wanted to be pedantic and careful
we could split the functional change to not enable to continue in case of failure
onto the next directory, and instead require that as a separate patch. I'll leave
it to Mimi to decide.

> 
>                 rc = fw_read_file_contents(file, buf);
>                 fput(file);
> -               if (rc)
> +               if (rc) {
>                         dev_warn(device, "loading %s failed with error %d\n",
>                                  path, rc);
> +                       continue;
> +               }
> +               dev_dbg(device, "direct-loading %s\n", buf->fw_id);
> +               fw_finish_direct_load(device, buf);
> -               else
> -                       break;
> +               break;
>         }
>         __putname(path);
> -
> -       if (!rc) {
> -               dev_dbg(device, "direct-loading %s\n",
> -                       buf->fw_id);
> -               fw_finish_direct_load(device, buf);
> -       }
> -
>         return rc;
>  }

Can you provided a Signed-offy-by? If so consider my Acked-by.

  Luis

  reply index

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 19:06 [PATCH v3 00/22] vfs: support for a common kernel file loader Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 01/22] ima: separate 'security.ima' reading functionality from collect Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 02/22] ima: refactor ima_policy_show() to display "ima_hooks" rules Mimi Zohar
2016-02-07 19:45   ` Petko Manolov
2016-02-10 19:33   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 03/22] ima: use "ima_hooks" enum as function argument Mimi Zohar
2016-02-07 19:46   ` Petko Manolov
2016-02-10 19:35   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 04/22] firmware: simplify dev_*() print messages for generic helpers Mimi Zohar
2016-02-04 17:26   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 05/22] firmware: move completing fw into a helper Mimi Zohar
2016-02-04 17:27   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 06/22] firmware: fold successful fw read early Mimi Zohar
2016-02-04 17:36   ` Kees Cook
2016-02-04 20:26     ` Luis R. Rodriguez [this message]
2016-02-03 19:06 ` [PATCH v3 07/22] vfs: define a generic function to read a file from the kernel Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 08/22] vfs: define kernel_read_file_id enumeration Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-04 19:45   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 09/22] ima: provide buffer hash calculation function Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 10/22] ima: calculate the hash of a buffer using aynchronous hash(ahash) Mimi Zohar
2016-02-10 19:58   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 11/22] ima: define a new hook to measure and appraise a file already in memory Mimi Zohar
2016-02-10 20:27   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 12/22] vfs: define kernel_read_file_from_path Mimi Zohar
2016-02-04 17:46   ` Kees Cook
2016-02-04 19:47   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 13/22] firmware: replace call to fw_read_file_contents() with kernel version Mimi Zohar
2016-02-04 17:56   ` Kees Cook
2016-02-04 19:51   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 14/22] security: define kernel_read_file hook Mimi Zohar
2016-02-04 17:57   ` Kees Cook
2016-02-04 19:54   ` Luis R. Rodriguez
2016-02-11 16:54   ` Casey Schaufler
2016-02-11 19:35     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 15/22] vfs: define kernel_copy_file_from_fd() Mimi Zohar
2016-02-04 17:58   ` Kees Cook
2016-02-04 19:55   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 16/22] module: replace copy_module_from_fd with kernel version Mimi Zohar
2016-02-04 18:04   ` Kees Cook
2016-02-04 19:56   ` Luis R. Rodriguez
2016-02-05  0:19     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 17/22] ima: remove firmware and module specific cached status info Mimi Zohar
2016-02-07 19:56   ` Petko Manolov
2016-02-10 20:18   ` Dmitry Kasatkin
2016-02-10 23:14     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 18/22] kexec: replace call to copy_file_from_fd() with kernel version Mimi Zohar
2016-02-04 18:05   ` Kees Cook
2016-02-04 19:57   ` Luis R. Rodriguez
2016-02-12 12:50   ` Dave Young
2016-02-03 19:06 ` [PATCH v3 19/22] ima: support for kexec image and initramfs Mimi Zohar
2016-02-07 20:10   ` Petko Manolov
2016-02-08 23:34     ` Mimi Zohar
2016-02-10 21:09   ` Dmitry Kasatkin
2016-02-10 23:21     ` Mimi Zohar
     [not found]       ` <CACE9dm8OJ1cgbKszUG-pCiEMVarUFLLWi_jewVV-JEMGAJsA-g@mail.gmail.com>
2016-02-11  2:08         ` Mimi Zohar
2016-02-11  8:47           ` Dmitry Kasatkin
2016-02-11 12:16             ` Mimi Zohar
2016-02-12 12:53   ` Dave Young
2016-02-12 13:09     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 20/22] ima: load policy using path Mimi Zohar
2016-02-07 19:59   ` Petko Manolov
2016-02-08  9:58     ` Dmitry Kasatkin
2016-02-08 10:35       ` Petko Manolov
2016-02-08 10:45         ` Dmitry Kasatkin
2016-02-08 21:12           ` Mimi Zohar
2016-02-09  7:47             ` Petko Manolov
2016-02-03 19:06 ` [PATCH v3 21/22] ima: measure and appraise the IMA policy itself Mimi Zohar
2016-02-07 20:01   ` Petko Manolov
2016-02-10 20:22   ` Dmitry Kasatkin
2016-02-10 23:15     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 22/22] ima: require signed IMA policy Mimi Zohar
2016-02-07 20:02   ` Petko Manolov
2016-02-10 20:24   ` Dmitry Kasatkin
2016-02-04 18:15 ` [PATCH v3 00/22] vfs: support for a common kernel file loader Kees Cook
2016-02-04 23:54   ` Mimi Zohar

Reply instructions:

You may reply publically 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=20160204202622.GH12481@wotan.suse.de \
    --to=mcgrof@suse.com \
    --cc=dhowells@redhat.com \
    --cc=dmitry.kasatkin@gmail.com \
    --cc=dmitry.torokhov@gmail.com \
    --cc=dwmw2@infradead.org \
    --cc=ebiederm@xmission.com \
    --cc=fsdevel@vger.kernel.org \
    --cc=keescook@chromium.org \
    --cc=kexec@lists.infradead.org \
    --cc=linux-modules@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=mcgrof@kernel.org \
    --cc=rusty@rustcorp.com.au \
    --cc=zohar@linux.vnet.ibm.com \
    /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: link

Linux-Modules Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-modules/0 linux-modules/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-modules linux-modules/ https://lore.kernel.org/linux-modules \
		linux-modules@vger.kernel.org linux-modules@archiver.kernel.org
	public-inbox-index linux-modules


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-modules


AGPL code for this site: git clone https://public-inbox.org/ public-inbox