Date: Thu, 3 Apr 2008 18:41:08 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: Digitally Signed Binaries w/ Kernel support, etc. Message-ID: <20080403164108.GA12190@slackbox.xs4all.nl> In-Reply-To: <ft2g30$7i7$2@ger.gmane.org> References: <47F3DA07.4020209@forrie.com> <20080402203859.GB80314@slackbox.xs4all.nl> <ft2g30$7i7$2@ger.gmane.org>
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--XsQoSWH+UP9D9v3l Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 03, 2008 at 01:46:39PM +0200, Ivan Voras wrote: > Roland Smith wrote: > > On Wed, Apr 02, 2008 at 03:09:59PM -0400, Forrest Aldrich wrote: > >> Does FreeBSD have support for digitally signed binary checking, simila= r to=20 > >> what Linux has with bsign and DigSig, where system binaries are signed= and=20 > >> this signature is verified before being run in the kernel? > >=20 > > If an attacker can modify binaries, he already has root privileges. In > > that case, what will stop him from creating a new pgp key and re-sign > > his doctered binaries? > >=20 > >> This would be very useful to have to further tighen-down the system. > >=20 > > As an alternative, on FreeBSD you can set the system immutable flag on > > binaries (see chflags(1)), and set the securelevel > 0. See > > init(8). Once this is set, not even root can undo this. You have to > > reboot to reset the securelevel to -1. >=20 > Signing binaries could be naturally tied in with securelevel, where some > securelevel (1?) would mean kernel no longer accepts new keys. If you set the system immutable flag on the binaries, you cannot modify the= m at all at securelevel >0. Signing the binaries would be pointless in that case. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --XsQoSWH+UP9D9v3l Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.8 (FreeBSD) iEYEARECAAYFAkf1CKQACgkQEnfvsMMhpyUIZwCgimdDpoEgUWY9pKy/Zzm3VWDW ymoAnArmt7EXjRhmtXwl5qRzxvDG8kDQ =svlB -----END PGP SIGNATURE----- --XsQoSWH+UP9D9v3l--
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