From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/12950 Path: news.gmane.org!.POSTED!not-for-mail From: David CARLIER Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] proposal adding explicit_bzero Date: Tue, 26 Jun 2018 21:54:53 +0100 Message-ID: References: <20180626204341.GY1392@brightrain.aerifal.cx> <20180626205337.GA1392@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="0000000000006ffc7a056f91b655" X-Trace: blaine.gmane.org 1530046396 11020 195.159.176.226 (26 Jun 2018 20:53:16 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 26 Jun 2018 20:53:16 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-12966-gllmg-musl=m.gmane.org@lists.openwall.com Tue Jun 26 22:53:12 2018 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1fXuxa-0002lN-9D for gllmg-musl@m.gmane.org; Tue, 26 Jun 2018 22:53:10 +0200 Original-Received: (qmail 3829 invoked by uid 550); 26 Jun 2018 20:55:18 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 3753 invoked from network); 26 Jun 2018 20:55:17 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=HhkynJI4JGk7oITUEugWDpIrvcH3bbWoGAJ7dy+rvpc=; b=BK4j19rbQpkbbbJYqILra6WIauQCUR4vdAeTFhGXpZ8ZlKmdsBQLjJrCBlchWfZ9oa Plm3J+4vckxfL0i4bODJpGWxxjA8mnMTVSuZT7Aan/7Azq9G4U5lSmwjYvuMIvAGqDIP WtZgP+LDgBJE3sOqPzXLp5mqhGDRnNfZIYl9tZeJVFkdNhRuqEZHay0n1QsIUU5XfjLv V6ENeCtrxaNrlEJiFZHvBVcfvlkkzLKDK7zThVZqF8djDP1t+3ZawEqPpU8GuBv2rnz/ uAUf60atRRdIIDl1VgxWUorIS/Tnu1S+iHtHabdZHv3CrdrcsDyfKNfVJ++ZzUjYVBja 0LOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=HhkynJI4JGk7oITUEugWDpIrvcH3bbWoGAJ7dy+rvpc=; b=kyREN9+jMRf0Ca3412NanIPmHEUmTiEL7IAlHlAvwmkmI8+iA521mdVU3qlkRjvcMI 5Doryqx42DIyLqidkHciS9+eAdZD09VyTS25y+091YCroXt8HPGHxK69r0saSjRxOBcA G+jOcKfQB85EBE0Zzm9yPn0PNOHy7ln3LzjM6kkFEsVModT1Ct1lBZeVYhVfBztxH0P9 mamLEfjxky7+H7JYYNPspYWupJ/djeEfFkNIKX9mMvC8izuT1d9qTZv3Fdjg/p59XdvQ sRFFiSjcF3kHn8EqisMi2VUO74Q22/PFo7YA3QYF98uhfYmOSSl9O6tZmRruD3wrirYv FMzg== X-Gm-Message-State: APt69E3F5AvDIMbT67qn2RDx/pgjuBMO+Kgvb8enyoAPUaSBmXVCj5+r SYDMCdpVpVRdL+5pZpSKYBUHMtQt7N15DbR8hSw= X-Google-Smtp-Source: AAOMgpeRZ1uXPMoCbwNwKvFlSf5N7VKmC0lsQG5rGAVZqSX6YMCgRkAfimzvHKY45sCXFaLGhd/BjVWvMO9yfPbZyPc= X-Received: by 2002:aca:2c7:: with SMTP id 190-v6mr1832700oic.61.1530046505285; Tue, 26 Jun 2018 13:55:05 -0700 (PDT) In-Reply-To: <20180626205337.GA1392@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:12950 Archived-At: --0000000000006ffc7a056f91b655 Content-Type: text/plain; charset="UTF-8" Sure I do agree. Thanks. On Tue, 26 Jun 2018 at 21:53, Rich Felker wrote: > On Tue, Jun 26, 2018 at 09:48:47PM +0100, David CARLIER wrote: > > Yes true sorry :-|. > > No problem. Do you agree with my proposed fix and want me to make that > change and apply it? > > Rich > > > > On Tue, 26 Jun 2018 at 21:43, Rich Felker wrote: > > > > > On Fri, Jun 15, 2018 at 01:37:43PM +0000, David CARLIER wrote: > > > > Hi dear lists, > > > > this is my first message so forgive me if this idea had already been > > > rejected. > > > > > > It's definitely not rejected outright, and I think the consensus is > > > to adopt it. But.. > > > > > > > From c0a16cf96b96b009097d6ed656a2a7b8969e8399 Mon Sep 17 00:00:00 > 2001 > > > > From: David Carlier > > > > Date: Fri, 15 Jun 2018 13:30:09 +0000 > > > > Subject: [PATCH] string: adding simple explicit_bzero implementation. > > > > > > > > glibc implementing it and modern security based code starting > > > > using it widely, here a simple implementation using memory barrier. > > > > --- > > > > include/string.h | 1 + > > > > src/string/explicit_bzero.c | 8 ++++++++ > > > > 2 files changed, 9 insertions(+) > > > > create mode 100644 src/string/explicit_bzero.c > > > > > > > > diff --git a/include/string.h b/include/string.h > > > > index ce1dc300..795a2abc 100644 > > > > --- a/include/string.h > > > > +++ b/include/string.h > > > > @@ -82,6 +82,7 @@ void *memccpy (void *__restrict, const void > > > *__restrict, int, size_t); > > > > char *strsep(char **, const char *); > > > > size_t strlcat (char *, const char *, size_t); > > > > size_t strlcpy (char *, const char *, size_t); > > > > +void explicit_bzero (void *, size_t); > > > > #endif > > > > > > > > #ifdef _GNU_SOURCE > > > > diff --git a/src/string/explicit_bzero.c > b/src/string/explicit_bzero.c > > > > new file mode 100644 > > > > index 00000000..47dba3c7 > > > > --- /dev/null > > > > +++ b/src/string/explicit_bzero.c > > > > @@ -0,0 +1,8 @@ > > > > +#define _BSD_SOURCE > > > > +#include > > > > + > > > > +void explicit_bzero(void *d, size_t n) > > > > +{ > > > > + memset(d, 0, n); > > > > + __asm__ volatile("": "r="(d) :: "memory"); > > > > +} > > > > -- > > > > > > The constraint here looks wrong. Normally = is written before the > > > type, not after; I'm not sure if all compiler versions accept the > > > unusual form with it after. But more importantly you have it as an > > > output constraint, where it's essentially a dead store, such that the > > > asm block does nothing to make explicit_bzero force the memset to > > > happen. > > > > > > I think you meant for the constraint to be an input constraint "r"(d). > > > Does that sound right? > > > > > > Rich > > > > --0000000000006ffc7a056f91b655 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Sure I do agree. Thanks.

On Tue, 26 Jun 2018 at 21:53, Rich Felker <dalias@libc.org> wrote:
On Tue, Jun 26, 2018 at 09:48:47PM +0100, David CAR= LIER wrote:
> Yes true sorry :-|.

No problem. Do you agree with my proposed fix and want me to make that
change and apply it?

Rich


> On Tue, 26 Jun 2018 at 21:43, Rich Felker <dalias@libc.org> wrote:
>
> > On Fri, Jun 15, 2018 at 01:37:43PM +0000, David CARLIER wrote: > > > Hi dear lists,
> > > this is my first message so forgive me if this idea had alre= ady been
> > rejected.
> >
> > It's definitely not rejected outright, and I think the consen= sus is
> > to adopt it. But..
> >
> > > From c0a16cf96b96b009097d6ed656a2a7b8969e8399 Mon Sep 17 00:= 00:00 2001
> > > From: David Carlier <dcarlier@afilias.info>
> > > Date: Fri, 15 Jun 2018 13:30:09 +0000
> > > Subject: [PATCH] string: adding simple explicit_bzero implem= entation.
> > >
> > > glibc implementing it and modern security based code startin= g
> > > using it widely, here a simple implementation using memory b= arrier.
> > > ---
> > >=C2=A0 include/string.h=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 | 1 +
> > >=C2=A0 src/string/explicit_bzero.c | 8 ++++++++
> > >=C2=A0 2 files changed, 9 insertions(+)
> > >=C2=A0 create mode 100644 src/string/explicit_bzero.c
> > >
> > > diff --git a/include/string.h b/include/string.h
> > > index ce1dc300..795a2abc 100644
> > > --- a/include/string.h
> > > +++ b/include/string.h
> > > @@ -82,6 +82,7 @@ void *memccpy (void *__restrict, const voi= d
> > *__restrict, int, size_t);
> > >=C2=A0 char *strsep(char **, const char *);
> > >=C2=A0 size_t strlcat (char *, const char *, size_t);
> > >=C2=A0 size_t strlcpy (char *, const char *, size_t);
> > > +void explicit_bzero (void *, size_t);
> > >=C2=A0 #endif
> > >
> > >=C2=A0 #ifdef _GNU_SOURCE
> > > diff --git a/src/string/explicit_bzero.c b/src/string/explic= it_bzero.c
> > > new file mode 100644
> > > index 00000000..47dba3c7
> > > --- /dev/null
> > > +++ b/src/string/explicit_bzero.c
> > > @@ -0,0 +1,8 @@
> > > +#define _BSD_SOURCE
> > > +#include <string.h>
> > > +
> > > +void explicit_bzero(void *d, size_t n)
> > > +{
> > > +=C2=A0 =C2=A0 =C2=A0memset(d, 0, n);
> > > +=C2=A0 =C2=A0 =C2=A0__asm__ volatile("": "r= =3D"(d) :: "memory");
> > > +}
> > > --
> >
> > The constraint here looks wrong. Normally =3D is written before t= he
> > type, not after; I'm not sure if all compiler versions accept= the
> > unusual form with it after. But more importantly you have it as a= n
> > output constraint, where it's essentially a dead store, such = that the
> > asm block does nothing to make explicit_bzero force the memset to=
> > happen.
> >
> > I think you meant for the constraint to be an input constraint &q= uot;r"(d).
> > Does that sound right?
> >
> > Rich
> >
--0000000000006ffc7a056f91b655--