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 463E4C76190 for ; Mon, 22 Jul 2019 18:21:51 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 9A23B2190D for ; Mon, 22 Jul 2019 18:21:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Dj43T+n6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A23B2190D 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-16531-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5541 invoked by uid 550); 22 Jul 2019 18:21:44 -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 5480 invoked from network); 22 Jul 2019 18:21:43 -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=HTjPBTADUPMB5RaGA9y0UyTqoJ3Kfn/iq/tEhGgaR3M=; b=Dj43T+n6Vxg6cN3csQHecassw0CJtE++5r2L9ZQaygl4xXVA6mYVT88ZTYnI46lB+W UNIKPs2wU27c+wvDPegaFAoelU0c0duzUcGIdc9b/fPDUKuu5QlRlibQ/0HLFnvruEZ9 RY9iOqCmvHk4MAaJgioF+tjnWh1lxA7mBoapM= 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=HTjPBTADUPMB5RaGA9y0UyTqoJ3Kfn/iq/tEhGgaR3M=; b=loWAeq8crzw8UyHcSbcuSsCAoWDtKwraNh3SZs9wJazf5fqfgAov4/hmKgmnM8INQv uKKmt7WVLnY4XOMnKwYFtk6GChp+vEawBUjAoe0GD8uY2K59G0RnPmOYyAZgcpTjJmY/ uJwOqsLJNbgHobI7jI8IHUAFfeH6jttw8Q9396k1xSDQwrDbl2s7QMkjUC2c+PgfdYXc tYEgNUjfIyhDBecH9+uGpds70uL4Oe8yDu2IcX9VilT4qKT/ZvHZi9vSV7GNtKPnIl2d Tl0yrugv/DBly/rEMFdBQfqjTgDYXQhb1QTtSPjN6b9jOIHJiiINZtObNK0gmYqAfhjn MBQg== X-Gm-Message-State: APjAAAWf65lEcR+5sitGvGfmU7soJSHr3iQ/Gk4METiv3DkR3YiCjwFk RxE7yUmAHbvgXyM/vU5e90J6ZQ== X-Google-Smtp-Source: APXvYqxd3ea3RMFRO/3G58OJVS+XLsxkndJ9CGsP8Y9p3sWvtvNRL3X4fkjIxQDOHpdZdeRpM3Xcbg== X-Received: by 2002:a17:90b:8d8:: with SMTP id ds24mr2771111pjb.135.1563819691252; Mon, 22 Jul 2019 11:21:31 -0700 (PDT) Date: Mon, 22 Jul 2019 11:21:29 -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: <201907221119.9ECF3466@keescook> References: <1562219683-15474-1-git-send-email-nitin.r.gote@intel.com> <201907221031.8B87A9DE@keescook> <2c959c56c23d0052e5c35ecfa2f6051b17fb2798.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c959c56c23d0052e5c35ecfa2f6051b17fb2798.camel@perches.com> On Mon, Jul 22, 2019 at 10:58:15AM -0700, Joe Perches wrote: > On Mon, 2019-07-22 at 10:43 -0700, Joe Perches wrote: > > On Mon, 2019-07-22 at 10:33 -0700, Kees Cook wrote: > > > 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. > > > > I did that. It works. It's a lot of conversions. > > > > $ cat str.cpy.cocci > > @@ > > expression e1; > > expression e2; > > @@ > > > > - strscpy(e1, e2, sizeof(e1)) > > + stracpy(e1, e2) > > > > @@ > > expression e1; > > expression e2; > > @@ > > > > - strlcpy(e1, e2, sizeof(e1)) > > + stracpy(e1, e2) > > > > > Devil's advocate: this adds yet more string handling functions... will > > > this cause even more confusion? > > > > Documentation is good. > > Actual in-kernel use and examples better. > > btw: I just ran this again and it produces: > > $ spatch --in-place -sp-file str.cpy.cocci . > $ git checkout tools/ > $ git diff --shortstat > 958 files changed, 2179 insertions(+), 2655 deletions(-) Cool. Well, assuming no one hates this, let's do it. :) Can you send a more complete patch with docs, etc? Maybe Linus will take it for late in the next merge window, perhaps? -- Kees Cook