From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A2EAC7618F for ; Mon, 22 Jul 2019 17:34:00 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 8F34F21903 for ; Mon, 22 Jul 2019 17:33:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="ZowcOjJM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F34F21903 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16525-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 4082 invoked by uid 550); 22 Jul 2019 17:33:54 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 4050 invoked from network); 22 Jul 2019 17:33:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ax8I1mb7UwIFxfCmMJfuzkJQZA4WbZ7Ek1Ds9PvMQYU=; b=ZowcOjJMdxosv2QSzqf2eI08qVemvBx1XFUBmEfS4sU/PraJBWF671A5zObKnz4TfD zk/CQmr2CoQ/bq7hFwV/jk7C4Zl+sLHE/NGWoR8qwxKIwHpxQQ4RjoUJThjmRHvGEZgo CUZMefdwNypT9GNU3PI/XXImbp4GU9RlYE3TQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ax8I1mb7UwIFxfCmMJfuzkJQZA4WbZ7Ek1Ds9PvMQYU=; b=YsK0bY31Snv6nT5IITWa61e3z1UhkkiZyJThdzE24t+10vOtyK6oYdNTuERp60UD9S Spm701kBDYa/FQ2LvpcXw15gkvuzZt1Pzrz4Vu/KOA39PIc1zpc6fpbYpbHb9jlrPuvT 6G720RupLYhXGkgDmOP5aPD79qpBIiTHlTQncAmzgo1Bl+6kmfrxP2gB06bu3jAea5ob 8rO2YbP1V2+9wMAl1/Bu6ReTRshlOOOzWuoRFA++EYpx3QJ/gxB2OQWjTJVxBx9/emiD ofiXlsP0ls5SdexiHYOiwXTij+W4biVewdhI6olhnPTNY08U/DhMUCTbPxVz+qFtWs8y ceOA== X-Gm-Message-State: APjAAAWleiEMRTroVuIatnB4MiRMWHgR1zsAk6B0rszv4boWO88t5+JU YvtKakGmUkiKNQHBN0GkZ1SC4Q== X-Google-Smtp-Source: APXvYqyX5Rkq79yH7MiGBYeJZggeb9zVsBWnRCFtyBj046jkmfMHzDiZGrpNESNeWOyNSE0LXKj3OA== X-Received: by 2002:a17:902:7043:: with SMTP id h3mr48081374plt.10.1563816821309; Mon, 22 Jul 2019 10:33:41 -0700 (PDT) Date: Mon, 22 Jul 2019 10:33:39 -0700 From: Kees Cook To: Joe Perches Cc: Nitin Gote , akpm@linux-foundation.org, corbet@lwn.net, apw@canonical.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Rasmus Villemoes Subject: Re: [RFC PATCH] string.h: Add stracpy/stracpy_pad (was: Re: [PATCH] checkpatch: Added warnings in favor of strscpy().) Message-ID: <201907221031.8B87A9DE@keescook> References: <1562219683-15474-1-git-send-email-nitin.r.gote@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Jul 04, 2019 at 05:15:57PM -0700, Joe Perches wrote: > On Thu, 2019-07-04 at 13:46 -0700, Joe Perches wrote: > > On Thu, 2019-07-04 at 11:24 +0530, Nitin Gote wrote: > > > Added warnings in checkpatch.pl script to : > > > > > > 1. Deprecate strcpy() in favor of strscpy(). > > > 2. Deprecate strlcpy() in favor of strscpy(). > > > 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad(). > > > > > > Updated strncpy() section in Documentation/process/deprecated.rst > > > to cover strscpy_pad() case. > > [] > > I sent a patch series for some strscpy/strlcpy misuses. > > How about adding a macro helper to avoid the misuses like: > --- > include/linux/string.h | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/include/linux/string.h b/include/linux/string.h > index 4deb11f7976b..ef01bd6f19df 100644 > --- a/include/linux/string.h > +++ b/include/linux/string.h > @@ -35,6 +35,22 @@ ssize_t strscpy(char *, const char *, size_t); > /* Wraps calls to strscpy()/memset(), no arch specific code required */ > ssize_t strscpy_pad(char *dest, const char *src, size_t count); > > +#define stracpy(to, from) \ > +({ \ > + size_t size = ARRAY_SIZE(to); \ > + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \ > + \ > + strscpy(to, from, size); \ > +}) > + > +#define stracpy_pad(to, from) \ > +({ \ > + size_t size = ARRAY_SIZE(to); \ > + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \ > + \ > + strscpy_pad(to, from, size); \ > +}) > + > #ifndef __HAVE_ARCH_STRCAT > extern char * strcat(char *, const char *); > #endif This seems like a reasonable addition, yes. I think Coccinelle might actually be able to find all the existing strscpy(dst, src, sizeof(dst)) cases to jump-start this conversion. Devil's advocate: this adds yet more string handling functions... will this cause even more confusion? -- Kees Cook