Date: Sun, 18 May 2025 20:39:52 +0000 From: Shawn Webb <shawn.webb@hardenedbsd.org> To: Mitchell Horne <mhorne@freebsd.org> Cc: Kristof Provost <kp@freebsd.org>, Lexi Winter <ivy@freebsd.org>, src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: b61850c4e6f6 - main - bridge(4): default net.link.bridge.member_ifaddrs to false Message-ID: <ujaozh75ualvll62xplvsixea45txr5ms34s3oqgnqe3g4fzcj@rkbwovdqwx57> In-Reply-To: <94441836-bb03-4c80-b603-aaa2997c4d29@freebsd.org> References: <202505150004.54F04FhR046897@gitrepo.freebsd.org> <d839f137-b43b-416b-968f-439301f0a5c6@freebsd.org> <C5E86940-9C1B-428B-980B-693FE92E7AED@FreeBSD.org> <94441836-bb03-4c80-b603-aaa2997c4d29@freebsd.org>
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--vyhrsnil4f2vwizj Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: git: b61850c4e6f6 - main - bridge(4): default net.link.bridge.member_ifaddrs to false MIME-Version: 1.0 On Sun, May 18, 2025 at 01:37:30PM -0300, Mitchell Horne wrote: > On 5/17/25 18:57, Kristof Provost wrote: > > On 17 May 2025, at 23:18, Mitchell Horne wrote: > >=20 > > On 5/14/25 21:04, Lexi Winter wrote: > >=20 > > The branch main has been updated by ivy: > >=20 > > URL: https://cgit.FreeBSD.org/src/commit/? > > id=3Db61850c4e6f6b0f21b36da7238db969d9090309e <https:// > > cgit.FreeBSD.org/src/commit/? > > id=3Db61850c4e6f6b0f21b36da7238db969d9090309e> > >=20 > > commit b61850c4e6f6b0f21b36da7238db969d9090309e > > Author: Lexi Winter ivy@FreeBSD.org <mailto:ivy@FreeBSD.org> > > AuthorDate: 2025-05-14 14:26:24 +0000 > > Commit: Lexi Winter ivy@FreeBSD.org <mailto:ivy@FreeBSD.org> > > CommitDate: 2025-05-15 00:02:52 +0000 > >=20 > > |bridge(4): default net.link.bridge.member_ifaddrs to false As > > discussed on arch@, this behaviour is broken and confuses users, > > so disable it by default. For 15.0-RELEASE, allow it to be re- > > enabled using a sysctl, but the sysctl will be removed in 16.0R= =2E | > >=20 > > Hi Lexi, > >=20 > > I just updated my workstation past this commit. I found that my main > > ethernet interface didn't receive an IP address, and had to set the > > sysctl to proceed as before. > >=20 > > I have the following network configuration lines in my rc.conf: > >=20 > > cloned_interfaces=3D"bridge0 tap0" > >=20 > > This ought to do the trick: > >=20 > > ifconfig_bridge0=3D"DHCP addm re0 addm tap0=E2=80=9D > >=20 > > Ensure the address gets assigned to the bridge, not to a bridge member > > interface. > >=20 >=20 > Here is what I ended up with: >=20 > ifconfig_re0=3D"up" > cloned_interfaces=3D"bridge0 tap0" > ifconfig_bridge0=3D"DHCP addm re0 addm tap0" > synchronous_dhclient=3D"YES" I wonder if there is any security difference between DHCP on the physical interface versus the bridge. Having the bridge grab an IP via DHCP (or IPv6 SLAAC/DHCPv6) means that VMs much be trusted. If a VM is compromised, a threat actor could redirect traffic on the host by running their own DHCP service in the compromised VM. The question I have, though, is: is this an issue when the physical interface is used instead of the bridge for grabbing a dynamic IP? So, I guess I'm asking, is there any security difference between the following two configs: =3D=3D=3D=3D BEGIN CONFIG 1 =3D=3D=3D=3D ifconfig_re0=3D"DHCP" cloned_interfaces=3D"bridge0 tap0" ifconfig_bridge0=3D"addm re0 addm tap0" =3D=3D=3D=3D END CONFIG 1 =3D=3D=3D=3D =3D=3D=3D=3D BEGIN CONFIG 2 =3D=3D=3D=3D ifconfig_re0=3D"up" cloned_interfaces=3D"bridge0 tap0" ifconfig_bridge0=3D"DHCP addm re0 addm tap0" synchronous_dhclient=3D"YES" =3D=3D=3D=3D END CONFIG 2 =3D=3D=3D=3D Thanks, --=20 Shawn Webb Cofounder / Security Engineer HardenedBSD Signal Username: shawn_webb.74 Tor-ified Signal: +1 303-901-1600 / shawn_webb_opsec.50 https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A= 4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc --vyhrsnil4f2vwizj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEA6TL67gupaZ9nzhT/y5nonf44foFAmgqRYkACgkQ/y5nonf4 4foZ8g//ZtZzTpRGuhm6AqTVliV7NWAbnZf5aVGggtWVxGGPQPnfJbYwJirQKLgQ 9JM/NOtKpM7cIcqKFpIntobc4ZqVYYcmQlHGyyBeoemCodske4vWflNbinVbl5SX Xcrqt6MjQt56KUy6FqLbNiHqBOuPz6cONpBulK/7uyXIGUIgEo67pA/WIWiqfPr6 d5KT25d5SY68nZnB4IjZ/zadPeG7FS40gi6aeDSw8DmuUaHvzSRvVzdBsWpEOpEU vhX2+lsL2mYhk2/nKUZYEp23+/0f2VHNSIIqPok+wD3zEQ7mUNY/quBJjZ/kNele zyP1AJBqe2nrqgvpuvtp6Kv5b6kmtbArKo4j+6ZNtqlBnUx4EFgsPgNEXk9IyL+j 2n8Mj7Rr2ekhfg2xpG/2kGX7FlsKGNDplpqzVcGNHrwW7X5U8J5npFhL0BCOSeRv 1XykhxP1F/zEgkO+jjWKASPTlvWLUQ/L8cgu+//C6jGGm2juR1DFoDcFOLP08y1G rFTeF/f6cqBVwE0c90mPKM6zdfC//BsBTqaQI6f5ERmG4SAhAiQsTGpmg/Dg+/gB 5pBVZB+yP4jDN0Vpdt6sYksh3F/bbz7RynizMTvVrZfTodjQTzFa3of7t5NIR90y U0r7+IpH1sQKp18pKNsBlUCUiF2YIveu1MTHofH5oAim/4L2a/I= =dC7m -----END PGP SIGNATURE----- --vyhrsnil4f2vwizj--
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