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From 212708dee7c5c483dd0ce76889f7e20abba7f859 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Thu, 30 Jun 2022 14:20:48 +0200
Subject: [PATCH] guestfish, guestmount: enable networking for "--key
ID:clevis"
Call the C-language helper key_store_requires_network() in guestfish and
guestmount.
(Short log for the "common" submodule, 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>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <20220630122048.19335-4-lersek@redhat.com>
(cherry picked from commit 6a5b44f538065a9f661510234a4235bf38348213)
---
common | 2 +-
fish/fish.c | 3 +++
fuse/guestmount.c | 4 ++++
3 files changed, 8 insertions(+), 1 deletion(-)
Submodule common 35467027f..af6cb55bc:
diff --git a/common/options/decrypt.c b/common/options/decrypt.c
index 1cd7b627e..97c8b88d1 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 90a3b15c5..6bc04df17 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 d27a7123e..d987ae561 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 80df91a85..60d5d8064 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/fish/fish.c b/fish/fish.c
index 23d9bb94f..19e3d2799 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -476,6 +476,9 @@ main (int argc, char *argv[])
/* If we've got drives to add, add them now. */
add_drives (drvs);
+ if (key_store_requires_network (ks) && guestfs_set_network (g, 1) == -1)
+ exit (EXIT_FAILURE);
+
/* If we've got mountpoints or prepared drives or -i option, we must
* launch the guest and mount them.
*/
diff --git a/fuse/guestmount.c b/fuse/guestmount.c
index 77c534828..3c6d57bde 100644
--- a/fuse/guestmount.c
+++ b/fuse/guestmount.c
@@ -348,6 +348,10 @@ main (int argc, char *argv[])
/* Do the guest drives and mountpoints. */
add_drives (drvs);
+
+ if (key_store_requires_network (ks) && guestfs_set_network (g, 1) == -1)
+ exit (EXIT_FAILURE);
+
if (guestfs_launch (g) == -1)
exit (EXIT_FAILURE);
if (inspector)
--
2.31.1
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