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From: Al Viro <viro@zeniv.linux.org.uk>
To: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
	linux-security-module@vger.kernel.org,
	Brad Spengler <spender@grsecurity.net>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Christoph Hellwig <hch@infradead.org>,
	James Morris <james.l.morris@oracle.com>,
	Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
	PaX Team <pageexec@freemail.hu>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v5 06/12] S.A.R.A.: WX protection
Date: Sat, 6 Jul 2019 20:28:53 +0100	[thread overview]
Message-ID: <20190706192852.GO17978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1562410493-8661-7-git-send-email-s.mesoraca16@gmail.com>

On Sat, Jul 06, 2019 at 12:54:47PM +0200, Salvatore Mesoraca wrote:

> +#define sara_warn_or_return(err, msg) do {		\
> +	if ((sara_wxp_flags & SARA_WXP_VERBOSE))	\
> +		pr_wxp(msg);				\
> +	if (!(sara_wxp_flags & SARA_WXP_COMPLAIN))	\
> +		return -err;				\
> +} while (0)
> +
> +#define sara_warn_or_goto(label, msg) do {		\
> +	if ((sara_wxp_flags & SARA_WXP_VERBOSE))	\
> +		pr_wxp(msg);				\
> +	if (!(sara_wxp_flags & SARA_WXP_COMPLAIN))	\
> +		goto label;				\
> +} while (0)

No.  This kind of "style" has no place in the kernel.

Don't hide control flow.  It's nasty enough to reviewers,
but it's pure hell on anyone who strays into your code while
chasing a bug or doing general code audit.  In effect, you
are creating your oh-so-private C dialect and assuming that
everyone who ever looks at your code will start with learning
that *AND* incorporating it into their mental C parser.
I'm sorry, but you are not that important.

If it looks like a function call, a casual reader will assume
that this is exactly what it is.  And when one is scanning
through a function (e.g. to tell if handling of some kind
of refcounts is correct, with twentieth grep through the
tree having brought something in your code into the view),
the last thing one wants is to switch between the area-specific
C dialects.  Simply because looking at yours is sandwiched
between digging through some crap in drivers/target/ and that
weird thing in kernel/tracing/, hopefully staying limited
to 20 seconds of glancing through several functions in your
code.

Don't Do That.  Really.

  parent reply	other threads:[~2019-07-06 19:29 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-06 10:54 [PATCH v5 00/12] S.A.R.A. a new stacked LSM Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 01/12] S.A.R.A.: add documentation Salvatore Mesoraca
2019-07-06 17:14   ` Randy Dunlap
2019-07-06 17:32     ` Salvatore Mesoraca
2019-07-13  0:14   ` James Morris
2019-07-06 10:54 ` [PATCH v5 02/12] S.A.R.A.: create framework Salvatore Mesoraca
2019-07-06 15:29   ` Randy Dunlap
2019-07-06 10:54 ` [PATCH v5 03/12] S.A.R.A.: cred blob management Salvatore Mesoraca
2019-07-12 23:35   ` James Morris
2019-07-06 10:54 ` [PATCH v5 04/12] S.A.R.A.: generic DFA for string matching Salvatore Mesoraca
2019-07-06 18:32   ` Jann Horn
2019-07-07 16:01     ` Salvatore Mesoraca
2019-07-08 17:37       ` Jann Horn
2019-10-06 16:49       ` Salvatore Mesoraca
2019-10-07 12:40         ` Jann Horn
2019-07-06 10:54 ` [PATCH v5 05/12] LSM: creation of "check_vmflags" LSM hook Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 06/12] S.A.R.A.: WX protection Salvatore Mesoraca
2019-07-06 15:38   ` Randy Dunlap
2019-07-06 19:28   ` Al Viro [this message]
2019-07-07 15:49     ` Salvatore Mesoraca
2019-07-09  4:51       ` Kees Cook
2019-07-08 12:42   ` David Laight
2019-07-06 10:54 ` [PATCH v5 07/12] LSM: creation of "pagefault_handler" LSM hook Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 08/12] S.A.R.A.: trampoline emulation Salvatore Mesoraca
2019-07-06 15:31   ` Randy Dunlap
2019-07-06 10:54 ` [PATCH v5 09/12] S.A.R.A.: WX protection procattr interface Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 10/12] S.A.R.A.: XATTRs support Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 11/12] S.A.R.A.: /proc/*/mem write limitation Salvatore Mesoraca
2019-07-06 18:20   ` Jann Horn
2019-07-07 16:15     ` Salvatore Mesoraca
2019-07-06 10:54 ` [PATCH v5 12/12] MAINTAINERS: take maintainership for S.A.R.A Salvatore Mesoraca
2019-07-06 14:33 ` [PATCH v5 00/12] S.A.R.A. a new stacked LSM Jordan Glover
2019-07-06 15:02   ` Salvatore Mesoraca
2019-07-07  1:16 ` James Morris
2019-07-07 15:40   ` Salvatore Mesoraca

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