Re: [Libguestfs] [libguestfs PATCH 2/3] introduce the "clevis_luks_unlock" API

On Tue, Jun 28, 2022 at 01:54:17PM +0200, Laszlo Ersek wrote: > Introduce a new guestfs API called "clevis_luks_unlock". At the libguestfs > level, it is quite simple; it wraps the "clevis luks unlock" guest command > (implemented by the "clevis-luks-unlock" executable, which is in fact a > shell script). > > The complexity is instead in the network-based disk encryption > (Clevis/Tang) scheme. Useful documentation: > > - https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/... > - https://github.com/latchset/clevis#clevis > - https://github.com/latchset/tang#tang > > The package providing "clevis-luks-unlock" is usually called > "clevis-luks", occasionally "clevis". Some distros don't package clevis at > all. Add the new API under a new option group (which may not be available) > called "clevisluks". > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1809453 > Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; > --- > daemon/Makefile.am | 1 + > generator/actions_core.ml | 38 +++++++++++++ > generator/proc_nr.ml | 1 + > daemon/clevis-luks.c | 58 ++++++++++++++++++++ > appliance/packagelist.in | 4 ++ > lib/MAX_PROC_NR | 2 +- > lib/guestfs.pod | 19 +++++-- > 7 files changed, 118 insertions(+), 5 deletions(-) > > diff --git a/daemon/Makefile.am b/daemon/Makefile.am > index bbd49f9ea1e0..f50faecd6930 100644 > --- a/daemon/Makefile.am > +++ b/daemon/Makefile.am > @@ -96,10 +96,11 @@ guestfsd_SOURCES = \ > btrfs.c \ > caml-stubs.c \ > cap.c \ > checksum.c \ > cleanups.c \ > + clevis-luks.c \ > cmp.c \ > command.c \ > command.h \ > compress.c \ > copy.c \ > diff --git a/generator/actions_core.ml b/generator/actions_core.ml > index 807150615426..1b1fdcf77209 100644 > --- a/generator/actions_core.ml > +++ b/generator/actions_core.ml > @@ -9718,6 +9718,44 @@ and I<not> the name of the underlying block device." }; > style = RErr, [String (Pathname, "dir"); String (FileOut, "filename")], []; > visibility = VInternal; > shortdesc = "read directories entries"; > longdesc = "Internal function for readdir." }; > > + { defaults with > + name = "clevis_luks_unlock"; added = (1, 49, 3); > + style = RErr, > + [String (Device, "device"); String (PlainString, "mapname")], PlainString because we create the device from the mapname, we're not passing (this) device in as a parameter, so this is correct. However do we never need any optional parameters? cryptsetup_open has [OBool "readonly"; OString "crypttype"].

> + []; > + optional = Some "clevisluks"; > + test_excuse = "needs networking and a configured Tang server"; > + shortdesc = "open an encrypted LUKS block device with Clevis and Tang"; > + longdesc = "\ > +This command opens a block device that has been encrypted according to the Linux > +Unified Key Setup (LUKS) standard, using network-bound disk encryption (NBDE). > + > +C<device> is the encrypted block device. > + > +The appliance will connect to the Tang servers noted in the tree of Clevis pins > +that is bound to a keyslot of the LUKS header. The Clevis pin tree may comprise > +C<sss> (redudancy) pins as internal nodes (optionally), and C<tang> pins as > +leaves. C<tpm2> pins are not supported. The appliance unlocks the encrypted > +block device by combining responses from the Tang servers with metadata from the > +LUKS header; there is no C<key> parameter. > + > +This command will fail if networking has not been enabled for the appliance. > +Refer to C<guestfs_set_network>. > + > +The command creates a new block device called F</dev/mapper/mapname>. Reads and > +writes to this block device are decrypted from and encrypted to the underlying > +C<device> respectively. Close the decrypted block device with > +C<guestfs_cryptsetup_close>. > + > +C<mapname> cannot be C<\"control\"> because that name is reserved by > +device-mapper. > + > +If this block device contains LVM volume groups, then calling > +C<guestfs_lvm_scan> with the C<activate> parameter C<true> will make them > +visible. > + > +Use C<guestfs_list_dm_devices> to list all device mapper devices." }; Some lines here are longer than 80 characters,

which might cause problems. Be better to stick to a bit less than 80 chars.

> ] > diff --git a/generator/proc_nr.ml b/generator/proc_nr.ml > index bdced51c9acd..edd9bd99d2da 100644 > --- a/generator/proc_nr.ml > +++ b/generator/proc_nr.ml > @@ -512,10 +512,11 @@ let proc_nr = [ > 507, "luks_uuid"; > 508, "cryptsetup_open"; > 509, "cryptsetup_close"; > 510, "internal_list_rpm_applications"; > 511, "internal_readdir"; > +512, "clevis_luks_unlock" > ] > > (* End of list. If adding a new entry, add it at the end of the list > * above. Do not modify anything below this line. > *---------------------------------------------------------------------- > diff --git a/daemon/clevis-luks.c b/daemon/clevis-luks.c > new file mode 100644 > index 000000000000..d3d970d78098 > --- /dev/null > +++ b/daemon/clevis-luks.c > @@ -0,0 +1,58 @@ > +/* libguestfs - the guestfsd daemon > + * Copyright (C) 2009-2022 Red Hat Inc. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, write to the Free Software > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. > + */ > + > +#include <config.h> > + > +#include "daemon.h" > +#include "actions.h" > +#include "optgroups.h" > + > +#define MAX_ARGS 8 > + > +int > +optgroup_clevisluks_available (void) > +{ > + return prog_exists ("clevis-luks-unlock"); > +} > + > +int > +do_clevis_luks_unlock (const char *device, const char *mapname) > +{ > + const char *argv[MAX_ARGS]; > + size_t i = 0; > + int r; > + CLEANUP_FREE char *err = NULL; > + > + ADD_ARG (argv, i, "clevis"); > + ADD_ARG (argv, i, "luks"); > + ADD_ARG (argv, i, "unlock"); > + ADD_ARG (argv, i, "-d"); > + ADD_ARG (argv, i, device); > + ADD_ARG (argv, i, "-n"); > + ADD_ARG (argv, i, mapname); > + ADD_ARG (argv, i, NULL); > + > + r = commandv (NULL, &err, argv); > + if (r == -1) { > + reply_with_error ("%s: %s: %s", device, mapname, err); > + return -1; > + } > + > + udev_settle (); > + return 0; > +} > diff --git a/appliance/packagelist.in b/appliance/packagelist.in > index 77a07acc6ad0..0b79edcdd55d 100644 > --- a/appliance/packagelist.in > +++ b/appliance/packagelist.in > @@ -21,10 +21,11 @@ dnl ./configure --with-extra-packages="gdb valgrind [etc]" > > dnl Basically the same with a few minor tweaks. > ifelse(UBUNTU,1,`define(`DEBIAN',1)') > > ifelse(REDHAT,1, > + clevis-luks > cryptsetup > cryptsetup-luks dnl old name used before Fedora 17 > dhclient > gfs-utils > gfs2-utils > @@ -51,10 +52,11 @@ ifelse(REDHAT,1, > > ifelse(DEBIAN,1, > bsdmainutils > dnl old name used in Jessie and earlier > btrfs-tools > + clevis-luks > cryptsetup > dash > extlinux > dnl gfs-tools, gfs2-tools have been renamed to gfs2-utils > gfs-tools > @@ -90,10 +92,11 @@ dnl iproute has been renamed to iproute2 > ) > > ifelse(ARCHLINUX,1, > cdrkit > cdrtools > + clevis > cryptsetup > dhclient > dhcpcd > gptfdisk > grub > @@ -117,10 +120,11 @@ ifelse(ARCHLINUX,1, > ifelse(SUSE,1, > dnl It seems no other augeas package depends on it. > augeas-lenses > btrfsprogs > cdrkit-cdrtools-compat > + clevis > cryptsetup > dhcpcd > dhcp-client > glibc-locale > gptfdisk > diff --git a/lib/MAX_PROC_NR b/lib/MAX_PROC_NR > index c0556fb20f37..4d0e90cbcbaf 100644 > --- a/lib/MAX_PROC_NR > +++ b/lib/MAX_PROC_NR > @@ -1 +1 @@ > -511 > +512 > diff --git a/lib/guestfs.pod b/lib/guestfs.pod > index 1ad44e7c2878..e10bf1fbec30 100644 > --- a/lib/guestfs.pod > +++ b/lib/guestfs.pod > @@ -589,15 +589,26 @@ devices. For LUKS it returns the string C<crypto_LUKS>. > For Windows BitLocker it returns C<BitLocker>. > > Then open these devices by calling L</guestfs_cryptsetup_open>. > Obviously you will require the passphrase! > > +Passphrase-less unlocking is supported for LUKS (not BitLocker) > +block devices that have been encrypted with network-bound disk > +encryption (NBDE), using Clevis on the Linux guest side, and > +Tang on a separate Linux server. Open such devices with > +L</guestfs_clevis_luks_unlock>. The appliance will need > +networking enabled (refer to L</guestfs_set_network>) and actual > +connectivity to the Tang servers noted in the C<tang> Clevis > +pins that are bound to the LUKS header. (This includes the > +ability to resolve the names of the Tang servers.) > + > Opening an encrypted device creates a new device mapper device > -called F</dev/mapper/mapname> (where C<mapname> is the > -string you supply to L</guestfs_cryptsetup_open>). > -Reads and writes to this mapper device are decrypted from and > -encrypted to the underlying block device respectively. > +called F</dev/mapper/mapname> (where C<mapname> is the string > +you supply to L</guestfs_cryptsetup_open> or > +L</guestfs_clevis_luks_unlock>). Reads and writes to this mapper > +device are decrypted from and encrypted to the underlying block > +device respectively. > > LVM volume groups on the device can be made visible by calling > L</guestfs_vgscan> followed by L</guestfs_vg_activate_all>. > The logical volume(s) can now be mounted in the usual way. Looks generally OK. Rich.