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(* virt-sysprep
* Copyright (C) 2012-2020 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.
*)
(* It's important that we write a random seed if we possibly can.
* Unfortunately some installers (hello, Debian) don't include the file
* in the basic guest, so we have to work out where to create it.
*)
let rec set_random_seed (g : Guestfs.guestfs) root =
let typ = g#inspect_get_type root in
let created = ref false in
if typ = "linux" then (
let files = [
"/var/lib/random-seed"; (* Fedora *)
"/var/lib/systemd/random-seed"; (* Fedora after F20? *)
"/var/lib/urandom/random-seed"; (* Debian *)
"/var/lib/misc/random-seed"; (* SuSE *)
"/etc/random-seed"; (* CirrOS *)
] in
List.iter (
fun file ->
if g#is_file file then (
make_random_seed_file g file ~exists:true;
created := true
)
) files;
);
if not !created then (
(* Backup plan: Try to create a new file. *)
let distro = g#inspect_get_distro root in
let file =
match typ, distro with
| "linux", ("fedora"|"rhel"|"centos"|"scientificlinux"|"oraclelinux"|"redhat-based") ->
Some "/var/lib/random-seed"
| "linux", ("debian"|"ubuntu"|"kalilinux") ->
Some "/var/lib/urandom/random-seed"
| "linux", ("opensuse"|"sles"|"suse-based") ->
Some "/var/lib/misc/random-seed"
| "linux", "cirros" ->
Some "/etc/random-seed"
| _ ->
None in
match file with
| Some file ->
let dir =
let i = String.rindex file '/' in
String.sub file 0 i in
if g#is_dir dir then (
make_random_seed_file g file;
created := true
)
| None -> ()
);
!created
and make_random_seed_file ?exists g file =
let file_exists =
match exists with
| None -> g#is_file file
| Some b -> b in
let n =
if file_exists then (
let n = Int64.to_int (g#filesize file) in
(* This file is usually 512 bytes in size. However during
* guest creation of some guests it can be just 8 bytes long.
* Cap the file size to [512, 8192] bytes.
*)
min (max n 512) 8192
)
else
(* Default to 512 bytes of randomness. *)
512 in
(* Get n bytes of randomness from the host. *)
let entropy = Urandom.urandom_bytes n in
if file_exists then (
(* Truncate the original file and append, in order to
* preserve original permissions.
*)
g#truncate file;
g#write_append file entropy
)
else (
(* Create a new file, set the permissions restrictively. *)
g#write file entropy;
g#chown 0 0 file;
g#chmod 0o600 file
)
|
