On Wed, Oct 14, 2020 at 02:41:51PM +0100, Stuart Henderson wrote:
> Just found this in my local tree still, iirc danj liked it but there
> wasn't much other enthusiasm. Any other comments? Should I just drop
> the diff? Change 'a' to use 2^10 minimum? Change to fixed 2^10 with
> no auto measurement?
I think this makes sense. I like it.
ok kmos
--Kurt
> ----- Forwarded message from Stuart Henderson <s...@spacehopper.org> -----
>
> From: Stuart Henderson <s...@spacehopper.org>
> Date: Sat, 23 May 2020 22:08:11 +0100
> Subject: Re: Remove useless line from daemon class in login.conf
>
> On 2020/05/22 16:04, Theo de Raadt wrote:
> > Stuart Henderson <s...@spacehopper.org> wrote:
> >
> > > On 2020/05/22 17:06, Daniel Jakots wrote:
> > > > Hi,
> > > >
> > > > We used to have different numbers of blowfish rounds between the
> > > > default and daemon classes in login.conf. On Jun 26, 2016, tedu
> > > > committed "upgrade selected login.conf to use auto rounds for bcrypt"
> > > > for amd64, sparc64, i386, and maccpc [1].
> > > >
> > > > Since the class daemon inherits from the default class, the
> > > > :localcipher=blowfish,a:\
> > > > is a duplicate.
> > > >
> > > > Here's a diff to remove them.
> > >
> > > I'm OK with unifying these settings, but FWIW I never switched to auto
> > > for these, it doesn't seem all that sensible for somebody with the ability
> > > to generate enough load on the machine to be able to reduce the strength
> > > of bcrypt down to the 64 (2^6) rounds minimum.
> >
> > Yes, that is problematic.
> >
> > The minimum should be probably be raised, we should consider if auto
> > should even exist anymore.
> >
>
> As long as it doesn't allow weakening things I think auto should still
> exist so that machines can have a stronger bcrypt where it's cheap.
>
> When this was introduced, login.conf for amd64/i386/macppc/sparc64
> changed from 8 (normal users) and 9 (daemon class i.e. root) to auto.
> Since other, mainly slower, arches stayed with hardcoded 8/9 I don't
> think the current minimum reachable in the code makes sense at all.
>
> I've gone to a few machines and done:
>
> - 50 runs of "encrypt -b a" to see what setting was chosen by auto
>
> for i in `jot 50`; do echo foo | encrypt -b a; sleep .1; done | cut -d'$' -f3
> | sort | uniq -c
>
> - 50 runs of "encrypt -b 9" or "encrypt -b 10" and averaged, to see
> how long those two settings take
>
> time for i in `jot 50`; do echo foo | encrypt -b 10; done
> (divided by 50)
>
> Chosen -b 9 -b 10
> Cortex-A53 1.4GHz (pi3) all 8 0.22 0.40
> GX-412TC 1GHz (APU2) all 8 0.16 0.31
> Cortex-A72 1.5GHz (pi4) all 9 0.07 0.14
> L5520 2.27GHz all 9 0.08 0.16
> E3-1225v3 3.2GHz 12x8 3x9 35x10 0.05 0.10
> E3-1240v5 3.5GHz all 10 0.04 0.08
> E3-1270v6 3.8GHz all 11 0.03 0.05
>
> I think bumping the minimum to 2^9 would be reasonable, there's a more
> noticeable delay on some machines but I think that's fair enough (any
> cracking is likely to be done on a fast machine, and the user can force
> it lower themselves if they want to take the risk).
>
> With a higher minimum than that the delay starts to get very noticeable
> in some cases, so I'm not sure we're ready for that yet.
>
> I think it also makes sense to use blowfish,a in login.conf on all
> arches, replacing the old 8/9. Actually -b a is already used in the
> installer for both root and the standard user on all archs, whatever
> they have in login.conf. Resulting in the situation that on some
> archs, the bcrypt created during install for root's password is
> weaker than it would be if reset after boot.
>
> So maybe this or something like it?
>
> Index: lib/libc/crypt/bcrypt.c
> ===================================================================
> RCS file: /cvs/src/lib/libc/crypt/bcrypt.c,v
> retrieving revision 1.57
> diff -u -p -r1.57 bcrypt.c
> --- lib/libc/crypt/bcrypt.c 26 Aug 2016 08:25:02 -0000 1.57
> +++ lib/libc/crypt/bcrypt.c 23 May 2020 20:16:46 -0000
> @@ -237,14 +237,15 @@ bcrypt_checkpass(const char *pass, const
> DEF_WEAK(bcrypt_checkpass);
>
> /*
> - * Measure this system's performance by measuring the time for 8 rounds.
> - * We are aiming for something that takes around 0.1s, but not too much over.
> + * Measure this system's performance by measuring the time for 2^9 rounds.
> + * We are aiming for something that takes around 0.1s, not too much over,
> + * but without allowing it to be too weak.
> */
> int
> _bcrypt_autorounds(void)
> {
> struct timespec before, after;
> - int r = 8;
> + int r = 9;
> char buf[_PASSWORD_LEN];
> int duration;
>
> @@ -257,12 +258,12 @@ _bcrypt_autorounds(void)
> duration += (after.tv_nsec - before.tv_nsec) / 1000;
>
> /* too quick? slow it down. */
> - while (r < 16 && duration <= 60000) {
> + while (r < 16 && duration <= 75000) {
> r += 1;
> duration *= 2;
> }
> /* too slow? speed it up. */
> - while (r > 6 && duration > 120000) {
> + while (r > 10 && duration > 120000) {
> r -= 1;
> duration /= 2;
> }
> Index: etc/etc.alpha/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.alpha/login.conf,v
> retrieving revision 1.8
> diff -u -p -r1.8 login.conf
> --- etc/etc.alpha/login.conf 5 Nov 2019 19:03:46 -0000 1.8
> +++ etc/etc.alpha/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.arm64/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.arm64/login.conf,v
> retrieving revision 1.7
> diff -u -p -r1.7 login.conf
> --- etc/etc.arm64/login.conf 5 Nov 2019 19:03:46 -0000 1.7
> +++ etc/etc.arm64/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.armv7/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.armv7/login.conf,v
> retrieving revision 1.8
> diff -u -p -r1.8 login.conf
> --- etc/etc.armv7/login.conf 5 Nov 2019 19:03:46 -0000 1.8
> +++ etc/etc.armv7/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.hppa/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.hppa/login.conf,v
> retrieving revision 1.10
> diff -u -p -r1.10 login.conf
> --- etc/etc.hppa/login.conf 5 Nov 2019 19:03:46 -0000 1.10
> +++ etc/etc.hppa/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.landisk/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.landisk/login.conf,v
> retrieving revision 1.8
> diff -u -p -r1.8 login.conf
> --- etc/etc.landisk/login.conf 5 Nov 2019 19:03:46 -0000 1.8
> +++ etc/etc.landisk/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.loongson/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.loongson/login.conf,v
> retrieving revision 1.13
> diff -u -p -r1.13 login.conf
> --- etc/etc.loongson/login.conf 12 Mar 2020 15:32:21 -0000 1.13
> +++ etc/etc.loongson/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.luna88k/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.luna88k/login.conf,v
> retrieving revision 1.8
> diff -u -p -r1.8 login.conf
> --- etc/etc.luna88k/login.conf 5 Nov 2019 19:03:46 -0000 1.8
> +++ etc/etc.luna88k/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.octeon/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.octeon/login.conf,v
> retrieving revision 1.10
> diff -u -p -r1.10 login.conf
> --- etc/etc.octeon/login.conf 5 Nov 2019 19:03:47 -0000 1.10
> +++ etc/etc.octeon/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
> Index: etc/etc.sgi/login.conf
> ===================================================================
> RCS file: /cvs/src/etc/etc.sgi/login.conf,v
> retrieving revision 1.10
> diff -u -p -r1.10 login.conf
> --- etc/etc.sgi/login.conf 5 Nov 2019 19:03:47 -0000 1.10
> +++ etc/etc.sgi/login.conf 23 May 2020 20:36:06 -0000
> @@ -48,7 +48,7 @@ default:\
> :openfiles-max=1024:\
> :openfiles-cur=512:\
> :stacksize-cur=4M:\
> - :localcipher=blowfish,8:\
> + :localcipher=blowfish,a:\
> :tc=auth-defaults:\
> :tc=auth-ftp-defaults:
>
> @@ -64,7 +64,6 @@ daemon:\
> :openfiles-max=1024:\
> :openfiles-cur=128:\
> :stacksize-cur=8M:\
> - :localcipher=blowfish,9:\
> :tc=default:
>
> #
>
>
> ----- End forwarded message -----
>
