Date: Thu, 19 Jan 2023 10:11:38 -0700 From: Alan Somers <asomers@freebsd.org> To: "Danilo G. Baio" <dbaio@freebsd.org> Cc: dev-commits-src-all@freebsd.org Subject: Re: git: 2c24ad3377a6 - main - ifconfig: abort if loading a module fails other than for ENOENT Message-ID: <CAOtMX2hv182P2HTAPkbYDZiwNxkV2-C%2BWp2%2BL0SpfDpqn2Zccw@mail.gmail.com> In-Reply-To: <2f4e4ccf-b19a-4f8f-a9e0-72298e500d7c@app.fastmail.com> References: <202301091857.309Iv87L068285@gitrepo.freebsd.org> <2f4e4ccf-b19a-4f8f-a9e0-72298e500d7c@app.fastmail.com>
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On Thu, Jan 19, 2023 at 7:03 AM Danilo G. Baio <dbaio@freebsd.org> wrote: > > > > On Mon, Jan 9, 2023, at 15:57, Alan Somers wrote: > > The branch main has been updated by asomers: > > > > URL: > > https://cgit.FreeBSD.org/src/commit/?id=2c24ad3377a6f584e484656db8390e4eb7cfc119 > > > > commit 2c24ad3377a6f584e484656db8390e4eb7cfc119 > > Author: Alan Somers <asomers@FreeBSD.org> > > AuthorDate: 2022-12-26 02:06:21 +0000 > > Commit: Alan Somers <asomers@FreeBSD.org> > > CommitDate: 2023-01-10 02:56:18 +0000 > > > > ifconfig: abort if loading a module fails other than for ENOENT > > > > If "ifconfig create" tries to load a kernel module, and the module > > exists but can't be loaded, fail the command with a useful error > > message. This is helpful, for example, when trying to create a cloned > > interface in a vnet jail. But ignore ENOENT, because sometimes ifconfig > > can't correctly guess the name of the required kernel module. > > > > MFC after: 2 weeks > > Reviewed by: jhb > > Differential Revision: https://reviews.freebsd.org/D37873 > > --- > > sbin/ifconfig/ifconfig.c | 18 +++++++++++++----- > > 1 file changed, 13 insertions(+), 5 deletions(-) > > > > diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c > > index 462d543125c4..120207a6927e 100644 > > --- a/sbin/ifconfig/ifconfig.c > > +++ b/sbin/ifconfig/ifconfig.c > > @@ -1719,11 +1719,19 @@ ifmaybeload(const char *name) > > } > > } > > > > - /* > > - * Try to load the module. But ignore failures, because ifconfig can't > > - * infer the names of all drivers (eg mlx4en(4)). > > - */ > > - (void) kldload(ifkind); > > + /* Try to load the module. */ > > + if (kldload(ifkind) < 0) { > > + switch (errno) { > > + case ENOENT: > > + /* > > + * Ignore ENOENT, because ifconfig can't infer the > > + * names of all drivers (eg mlx4en(4)). > > + */ > > + break; > > + default: > > + err(1, "kldload(%s)", ifkind); > > + } > > + } > > } > > > > static struct cmd basic_cmds[] = { > > > Hi. > > I have a jail with vnet where the interface is renamed that stopped working after this. > > from inside the jail: > > root@test:/ # ifconfig > lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 > options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6> > inet6 ::1 prefixlen 128 > inet6 fe80::1%lo0 prefixlen 64 scopeid 0x10 > inet 127.0.0.1 netmask 0xff000000 > groups: lo > nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> > vnet0b_test: flags=8862<BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > options=8<VLAN_MTU> > ether 02:27:72:a7:28:0b > groups: epair > media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>) > status: active > nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > root@test:/ # ifconfig vnet0b_test > ifconfig: kldload(if_vnet): Operation not permitted > > > If I don't rename the interface, that works. > > jail.conf: > > test { > vnet; > $index = "0"; > vnet.interface = "vnet${index}b_${name}"; > exec.prestart += "ifconfig epair${index} create"; > exec.prestart += "ifconfig ${bridge} addm epair${index}a"; > exec.prestart += "ifconfig epair${index}a up name vnet${index}a_${name}"; > exec.prestart += "ifconfig epair${index}b up name vnet${index}b_${name}"; > exec.poststop += "ifconfig ${bridge} deletem vnet${index}a_${name}"; > exec.poststop += "ifconfig vnet${index}a_${name} destroy"; > devfs_ruleset = "11"; # add path 'bpf*' unhide (devfs.rules) > } > > That's a bit odd, I know, could be using description instead. > > Just reporting. > > Regards. > -- > Danilo G. Baio Ugh, it looks like kldload(2) is doing the privilege check before the file existence check. I'm not sure of the best solution: * Change kern_kldload to check for file existence first. This would ring some alarm bells among security folks, and it isn't totally easy to do, either. * Change ifconfig(8) to do an existence check of its own. This would be ugly. * Change ifconfig(8) so that it doesn't attempt to load modules when just listing an interface. This might be incomplete, but is probably worth doing anyway.
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