[Libguestfs] [libguestfs PATCH 2/3] introduce the "clevis_luks_unlock" API
Laszlo Ersek
lersek at redhat.com
Tue Jun 28 11:54:17 UTC 2022
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/html-single/security_hardening/index#configuring-automated-unlocking-of-encrypted-volumes-using-policy-based-decryption_security-hardening
- 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 at redhat.com>
---
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")],
+ [];
+ 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." };
+
]
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.
--
2.19.1.3.g30247aa5d201
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