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From 94b57f647d67d4713284af1f0580d1afedd6ebaa Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Fri, 1 Jul 2022 15:30:42 +0200
Subject: [PATCH] convert: document networking dependency of "--key ID:clevis"
Virt-v2v enables appliance networking already, for the sake of
"unconfigure_vmware". We now have a second use case for networking: "--key
ID:clevis". Update the comment in the code.
(Short log for libguestfs-common commit range 35467027f657..af6cb55bc58a:
Laszlo Ersek (12):
options: fix UUID comparison logic bug in get_keys()
mltools/tools_utils: remove unused function "key_store_to_cli"
mltools/tools_utils: allow multiple "--key" options for OCaml tools too
options: replace NULL-termination with number-of-elements in get_keys()
options: wrap each passphrase from get_keys() into a struct
options: add back-end for LUKS decryption with Clevis+Tang
options: introduce selector type "key_clevis"
options: generalize "--key" selector parsing for C-language utilities
mltools/tools_utils-c: handle internal type error with abort()
mltools/tools_utils: generalize "--key" selector parsing for OCaml utils
options, mltools/tools_utils: parse "--key ID:clevis" options
options, mltools/tools_utils: add helper for network dependency
).
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1809453
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20220628115856.5820-1-lersek@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
(cherry picked from commit 98fa5ab2685371c681282ce5de704877af27be74)
---
common | 2 +-
convert/convert.ml | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
Submodule common 35467027..af6cb55b:
diff --git a/common/mltools/tools_utils-c.c b/common/mltools/tools_utils-c.c
index 08146677..4ff42e5d 100644
--- a/common/mltools/tools_utils-c.c
+++ b/common/mltools/tools_utils-c.c
@@ -62,24 +62,31 @@ guestfs_int_mllib_inspect_decrypt (value gv, value gpv, value keysv)
caml_raise_out_of_memory ();
v = Field (elemv, 1);
- switch (Tag_val (v)) {
- case 0: /* KeyString of string */
- key.type = key_string;
- key.string.s = strdup (String_val (Field (v, 0)));
- if (!key.string.s)
- caml_raise_out_of_memory ();
- break;
- case 1: /* KeyFileName of string */
- key.type = key_file;
- key.file.name = strdup (String_val (Field (v, 0)));
- if (!key.file.name)
- caml_raise_out_of_memory ();
- break;
- default:
- error (EXIT_FAILURE, 0,
- "internal error: unhandled Tag_val (v) = %d",
- Tag_val (v));
- }
+ if (Is_block (v))
+ switch (Tag_val (v)) {
+ case 0: /* KeyString of string */
+ key.type = key_string;
+ key.string.s = strdup (String_val (Field (v, 0)));
+ if (!key.string.s)
+ caml_raise_out_of_memory ();
+ break;
+ case 1: /* KeyFileName of string */
+ key.type = key_file;
+ key.file.name = strdup (String_val (Field (v, 0)));
+ if (!key.file.name)
+ caml_raise_out_of_memory ();
+ break;
+ default:
+ abort ();
+ }
+ else
+ switch (Int_val (v)) {
+ case 0: /* KeyClevis */
+ key.type = key_clevis;
+ break;
+ default:
+ abort ();
+ }
ks = key_store_import_key (ks, &key);
diff --git a/common/mltools/tools_utils.ml b/common/mltools/tools_utils.ml
index 695fda7e..562bfadc 100644
--- a/common/mltools/tools_utils.ml
+++ b/common/mltools/tools_utils.ml
@@ -29,11 +29,12 @@ open Getopt.OptionName
let prog = ref prog
type key_store = {
- keys : (string, key_store_key) Hashtbl.t;
+ keys : (string * key_store_key) list ref;
}
and key_store_key =
| KeyString of string
| KeyFileName of string
+ | KeyClevis
external c_inspect_decrypt : Guestfs.t -> int64 -> (string * key_store_key) list -> unit = "guestfs_int_mllib_inspect_decrypt"
external c_set_echo_keys : unit -> unit = "guestfs_int_mllib_set_echo_keys" [@@noalloc]
@@ -376,7 +377,7 @@ let create_standard_options argspec ?anon_fun ?(key_opts = false)
)
in
let ks = {
- keys = Hashtbl.create 13;
+ keys = ref [];
} in
let argspec = ref argspec in
let add_argspec = List.push_back argspec in
@@ -392,14 +393,28 @@ let create_standard_options argspec ?anon_fun ?(key_opts = false)
if key_opts then (
let parse_key_selector arg =
- let parts = String.nsplit ~max:3 ":" arg in
+ let parts = String.nsplit ":" arg in
match parts with
+ | [] ->
+ error (f_"selector '%s': missing ID") arg
+ | [ _ ] ->
+ error (f_"selector '%s': missing TYPE") arg
+ | [ _; "key" ]
+ | _ :: "key" :: _ :: _ :: _ ->
+ error (f_"selector '%s': missing KEY_STRING, or too many fields") arg
| [ device; "key"; key ] ->
- Hashtbl.replace ks.keys device (KeyString key)
+ List.push_back ks.keys (device, KeyString key)
+ | [ _; "file" ]
+ | _ :: "file" :: _ :: _ :: _ ->
+ error (f_"selector '%s': missing FILENAME, or too many fields") arg
| [ device; "file"; file ] ->
- Hashtbl.replace ks.keys device (KeyFileName file)
+ List.push_back ks.keys (device, KeyFileName file)
+ | _ :: "clevis" :: _ :: _ ->
+ error (f_"selector '%s': too many fields") arg
+ | [ device; "clevis" ] ->
+ List.push_back ks.keys (device, KeyClevis)
| _ ->
- error (f_"invalid selector string for --key: %s") arg
+ error (f_"selector '%s': invalid TYPE") arg
in
add_argspec ([ L"echo-keys" ], Getopt.Unit c_set_echo_keys, s_"Don’t turn off echo for passphrases");
@@ -420,16 +435,6 @@ let create_standard_options argspec ?anon_fun ?(key_opts = false)
let getopt = Getopt.create argspec ?anon_fun usage_msg in
{ getopt; ks; debug_gc }
-let key_store_to_cli { keys } =
- Hashtbl.fold (
- fun k v acc ->
- let arg =
- match v with
- | KeyString s -> sprintf "%s:key:%s" k s
- | KeyFileName f -> sprintf "%s:file:%s" k f in
- "--key" :: arg :: acc
- ) keys []
-
(* Run an external command, slurp up the output as a list of lines. *)
let external_command ?(echo_cmd = true) cmd =
if echo_cmd then
@@ -691,21 +696,19 @@ let is_btrfs_subvolume g fs =
if g#last_errno () = Guestfs.Errno.errno_EINVAL then false
else raise exn
+let key_store_requires_network ks =
+ List.exists (function
+ | _, KeyClevis -> true
+ | _ -> false) !(ks.keys)
+
let inspect_decrypt g ks =
- (* Turn the keys in the key_store into a simpler struct, so it is possible
- * to read it using the C API.
- *)
- let keys_as_list = Hashtbl.fold (
- fun k v acc ->
- (k, v) :: acc
- ) ks.keys [] in
(* Note we pass original 'g' even though it is not used by the
* callee. This is so that 'g' is kept as a root on the stack, and
* so cannot be garbage collected while we are in the c_inspect_decrypt
* function.
*)
c_inspect_decrypt g#ocaml_handle (Guestfs.c_pointer g#ocaml_handle)
- keys_as_list
+ !(ks.keys)
let with_timeout op timeout ?(sleep = 2) fn =
let start_t = Unix.gettimeofday () in
diff --git a/common/mltools/tools_utils.mli b/common/mltools/tools_utils.mli
index 50183006..ec900e63 100644
--- a/common/mltools/tools_utils.mli
+++ b/common/mltools/tools_utils.mli
@@ -103,14 +103,6 @@ val create_standard_options : Getopt.speclist -> ?anon_fun:Getopt.anon_fun -> ?k
Returns a new {!cmdline_options} structure. *)
-val key_store_to_cli : key_store -> string list
-(** Convert a {!key_store} object back to a list of command line
- options, essentially undoing the effect of Getopt parsing.
- This is used in virt-v2v to pass the keystore to helpers.
- It is not particularly secure, especially if you use the
- [:key:] selector, although not any less secure than passing
- them via the command line in the first place. *)
-
val external_command : ?echo_cmd:bool -> string -> string list
(** Run an external command, slurp up the output as a list of lines.
@@ -204,6 +196,10 @@ val inspect_mount_root_ro : Guestfs.guestfs -> string -> unit
val is_btrfs_subvolume : Guestfs.guestfs -> string -> bool
(** Checks if a filesystem is a btrfs subvolume. *)
+val key_store_requires_network : key_store -> bool
+(** [key_store_requires_network ks] returns [true] iff [ks] contains at least
+ one "ID:clevis" selector. *)
+
val inspect_decrypt : Guestfs.guestfs -> key_store -> unit
(** Simple implementation of decryption: look for any encrypted
partitions and decrypt them, then rescan for VGs. *)
diff --git a/common/options/decrypt.c b/common/options/decrypt.c
index 1cd7b627..97c8b88d 100644
--- a/common/options/decrypt.c
+++ b/common/options/decrypt.c
@@ -124,10 +124,10 @@ decrypt_mountables (guestfs_h *g, const char * const *mountables,
while ((mountable = *mnt_scan++) != NULL) {
CLEANUP_FREE char *type = NULL;
CLEANUP_FREE char *uuid = NULL;
- CLEANUP_FREE_STRING_LIST char **keys = NULL;
+ struct matching_key *keys;
+ size_t nr_matches;
CLEANUP_FREE char *mapname = NULL;
- const char * const *key_scan;
- const char *key;
+ size_t scan;
type = guestfs_vfs_type (g, mountable);
if (type == NULL)
@@ -144,33 +144,45 @@ decrypt_mountables (guestfs_h *g, const char * const *mountables,
/* Grab the keys that we should try with this device, based on device name,
* or UUID (if any).
*/
- keys = get_keys (ks, mountable, uuid);
- assert (keys[0] != NULL);
+ keys = get_keys (ks, mountable, uuid, &nr_matches);
+ assert (nr_matches > 0);
/* Generate a node name for the plaintext (decrypted) device node. */
if (uuid == NULL || asprintf (&mapname, "luks-%s", uuid) == -1)
mapname = make_mapname (mountable);
/* Try each key in turn. */
- key_scan = (const char * const *)keys;
- while ((key = *key_scan++) != NULL) {
+ for (scan = 0; scan < nr_matches; ++scan) {
+ struct matching_key *key = keys + scan;
int r;
guestfs_push_error_handler (g, NULL, NULL);
- r = guestfs_cryptsetup_open (g, mountable, key, mapname, -1);
+ assert (key->clevis == (key->passphrase == NULL));
+ if (key->clevis)
+#ifdef GUESTFS_HAVE_CLEVIS_LUKS_UNLOCK
+ r = guestfs_clevis_luks_unlock (g, mountable, mapname);
+#else
+ error (EXIT_FAILURE, 0,
+ _("'clevis_luks_unlock', needed for decrypting %s, is "
+ "unavailable in this libguestfs version"), mountable);
+#endif
+ else
+ r = guestfs_cryptsetup_open (g, mountable, key->passphrase, mapname,
+ -1);
guestfs_pop_error_handler (g);
if (r == 0)
break;
}
- if (key == NULL)
+ if (scan == nr_matches)
error (EXIT_FAILURE, 0,
_("could not find key to open LUKS encrypted %s.\n\n"
"Try using --key on the command line.\n\n"
"Original error: %s (%d)"),
mountable, guestfs_last_error (g), guestfs_last_errno (g));
+ free_keys (keys, nr_matches);
decrypted_some = true;
}
diff --git a/common/options/key-option.pod b/common/options/key-option.pod
index 90a3b15c..6bc04df1 100644
--- a/common/options/key-option.pod
+++ b/common/options/key-option.pod
@@ -14,4 +14,13 @@ Use the specified C<KEY_STRING> as passphrase.
Read the passphrase from F<FILENAME>.
+=item B<--key> C<ID>:clevis
+
+Attempt passphrase-less unlocking for C<ID> with Clevis, over the
+network. Please refer to L<guestfs(3)/ENCRYPTED DISKS> for more
+information on network-bound disk encryption (NBDE).
+
+Note that if any such option is present on the command line, QEMU user
+networking will be automatically enabled for the libguestfs appliance.
+
=back
diff --git a/common/options/keys.c b/common/options/keys.c
index d27a7123..d987ae56 100644
--- a/common/options/keys.c
+++ b/common/options/keys.c
@@ -125,11 +125,12 @@ read_first_line_from_file (const char *filename)
* keystore. There may be multiple. If none are read from the
* keystore, ask the user.
*/
-char **
-get_keys (struct key_store *ks, const char *device, const char *uuid)
+struct matching_key *
+get_keys (struct key_store *ks, const char *device, const char *uuid,
+ size_t *nr_matches)
{
- size_t i, j, nmemb;
- char **r;
+ size_t i, nmemb;
+ struct matching_key *r, *match;
char *s;
/* We know the returned list must have at least one element and not
@@ -139,22 +140,20 @@ get_keys (struct key_store *ks, const char *device, const char *uuid)
if (ks && ks->nr_keys > nmemb)
nmemb = ks->nr_keys;
- /* make room for the terminating NULL */
- if (nmemb == (size_t)-1)
+ if (nmemb > (size_t)-1 / sizeof *r)
error (EXIT_FAILURE, 0, _("size_t overflow"));
- nmemb++;
- r = calloc (nmemb, sizeof (char *));
+ r = malloc (nmemb * sizeof *r);
if (r == NULL)
- error (EXIT_FAILURE, errno, "calloc");
+ error (EXIT_FAILURE, errno, "malloc");
- j = 0;
+ match = r;
if (ks) {
for (i = 0; i < ks->nr_keys; ++i) {
struct key_store_key *key = &ks->keys[i];
- if (STRNEQ (key->id, device) && (uuid && STRNEQ (key->id, uuid)))
+ if (STRNEQ (key->id, device) && (!uuid || STRNEQ (key->id, uuid)))
continue;
switch (key->type) {
@@ -162,68 +161,101 @@ get_keys (struct key_store *ks, const char *device, const char *uuid)
s = strdup (key->string.s);
if (!s)
error (EXIT_FAILURE, errno, "strdup");
- r[j++] = s;
+ match->clevis = false;
+ match->passphrase = s;
+ ++match;
break;
case key_file:
s = read_first_line_from_file (key->file.name);
- r[j++] = s;
+ match->clevis = false;
+ match->passphrase = s;
+ ++match;
+ break;
+ case key_clevis:
+ match->clevis = true;
+ match->passphrase = NULL;
+ ++match;
break;
}
}
}
- if (j == 0) {
+ if (match == r) {
/* Key not found in the key store, ask the user for it. */
s = read_key (device);
if (!s)
error (EXIT_FAILURE, 0, _("could not read key from user"));
- r[0] = s;
+ match->clevis = false;
+ match->passphrase = s;
+ ++match;
}
+ *nr_matches = (size_t)(match - r);
return r;
}
+void
+free_keys (struct matching_key *keys, size_t nr_matches)
+{
+ size_t i;
+
+ for (i = 0; i < nr_matches; ++i) {
+ struct matching_key *key = keys + i;
+
+ assert (key->clevis == (key->passphrase == NULL));
+ if (!key->clevis)
+ free (key->passphrase);
+ }
+ free (keys);
+}
+
struct key_store *
key_store_add_from_selector (struct key_store *ks, const char *selector)
{
- CLEANUP_FREE_STRING_LIST char **fields =
- guestfs_int_split_string (':', selector);
+ CLEANUP_FREE_STRING_LIST char **fields = NULL;
+ size_t field_count;
struct key_store_key key;
+ fields = guestfs_int_split_string (':', selector);
if (!fields)
error (EXIT_FAILURE, errno, "guestfs_int_split_string");
+ field_count = guestfs_int_count_strings (fields);
- if (guestfs_int_count_strings (fields) != 3) {
- invalid_selector:
- error (EXIT_FAILURE, 0, "invalid selector for --key: %s", selector);
- }
-
- /* 1: device */
+ /* field#0: ID */
+ if (field_count < 1)
+ error (EXIT_FAILURE, 0, _("selector '%s': missing ID"), selector);
key.id = strdup (fields[0]);
if (!key.id)
error (EXIT_FAILURE, errno, "strdup");
- /* 2: key type */
- if (STREQ (fields[1], "key"))
+ /* field#1...: TYPE, and TYPE-specific properties */
+ if (field_count < 2)
+ error (EXIT_FAILURE, 0, _("selector '%s': missing TYPE"), selector);
+
+ if (STREQ (fields[1], "key")) {
key.type = key_string;
- else if (STREQ (fields[1], "file"))
- key.type = key_file;
- else
- goto invalid_selector;
-
- /* 3: actual key */
- switch (key.type) {
- case key_string:
+ if (field_count != 3)
+ error (EXIT_FAILURE, 0,
+ _("selector '%s': missing KEY_STRING, or too many fields"),
+ selector);
key.string.s = strdup (fields[2]);
if (!key.string.s)
error (EXIT_FAILURE, errno, "strdup");
- break;
- case key_file:
+ } else if (STREQ (fields[1], "file")) {
+ key.type = key_file;
+ if (field_count != 3)
+ error (EXIT_FAILURE, 0,
+ _("selector '%s': missing FILENAME, or too many fields"),
+ selector);
key.file.name = strdup (fields[2]);
if (!key.file.name)
error (EXIT_FAILURE, errno, "strdup");
- break;
- }
+ } else if (STREQ (fields[1], "clevis")) {
+ key.type = key_clevis;
+ if (field_count != 2)
+ error (EXIT_FAILURE, 0, _("selector '%s': too many fields"), selector);
+ } else
+ error (EXIT_FAILURE, 0, _("selector '%s': invalid TYPE"), selector);
return key_store_import_key (ks, &key);
}
@@ -252,6 +284,21 @@ key_store_import_key (struct key_store *ks, const struct key_store_key *key)
return ks;
}
+bool
+key_store_requires_network (const struct key_store *ks)
+{
+ size_t i;
+
+ if (ks == NULL)
+ return false;
+
+ for (i = 0; i < ks->nr_keys; ++i)
+ if (ks->keys[i].type == key_clevis)
+ return true;
+
+ return false;
+}
+
void
free_key_store (struct key_store *ks)
{
@@ -270,6 +317,9 @@ free_key_store (struct key_store *ks)
case key_file:
free (key->file.name);
break;
+ case key_clevis:
+ /* nothing */
+ break;
}
free (key->id);
}
diff --git a/common/options/options.h b/common/options/options.h
index 80df91a8..60d5d806 100644
--- a/common/options/options.h
+++ b/common/options/options.h
@@ -115,6 +115,7 @@ struct key_store_key {
enum {
key_string, /* key specified as string */
key_file, /* key stored in a file */
+ key_clevis, /* key reconstructed with Clevis+Tang */
} type;
union {
struct {
@@ -134,6 +135,19 @@ struct key_store {
size_t nr_keys;
};
+/* A key matching a particular ID (pathname of the libguestfs device node that
+ * stands for the encrypted block device, or LUKS UUID).
+ */
+struct matching_key {
+ /* True iff the passphrase should be reconstructed using Clevis, talking to
+ * Tang servers over the network.
+ */
+ bool clevis;
+
+ /* Explicit passphrase, otherwise. */
+ char *passphrase;
+};
+
/* in config.c */
extern void parse_config (void);
@@ -151,9 +165,12 @@ extern void print_inspect_prompt (void);
/* in key.c */
extern char *read_key (const char *param);
-extern char **get_keys (struct key_store *ks, const char *device, const char *uuid);
+extern struct matching_key *get_keys (struct key_store *ks, const char *device,
+ const char *uuid, size_t *nr_matches);
+extern void free_keys (struct matching_key *keys, size_t nr_matches);
extern struct key_store *key_store_add_from_selector (struct key_store *ks, const char *selector);
extern struct key_store *key_store_import_key (struct key_store *ks, const struct key_store_key *key);
+extern bool key_store_requires_network (const struct key_store *ks);
extern void free_key_store (struct key_store *ks);
/* in options.c */
diff --git a/convert/convert.ml b/convert/convert.ml
index 5e0e6c2b..b678dc92 100644
--- a/convert/convert.ml
+++ b/convert/convert.ml
@@ -57,7 +57,8 @@ let rec convert dir options source =
* sure this is not too large because each vCPU consumes guest RAM.
*)
g#set_smp (min 8 (Sysconf.nr_processors_online ()));
- (* The network is only used by the unconfigure_vmware () function. *)
+ (* The network is used by the unconfigure_vmware () function, and the "--key
+ * ID:clevis" command line options (if any). *)
g#set_network true;
List.iter (
fun { s_disk_id = i } ->
--
2.31.1
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