homed: move homectl's recovery key generation/modhex code to src/shared/

This allows us to later reuse the code to generate recovery keys for
traditional LUKS volumes, too and share the code.

src/basic/meson.build

@@ -187,6 +187,8 @@ basic_sources = files('''
         ratelimit.h
         raw-clone.h
         raw-reboot.h
+        recovery-key.c
+        recovery-key.h
         replace-var.c
         replace-var.h
         rlimit-util.c

src/basic/recovery-key.c

@@ -1,10 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
-
-#include "modhex.h"
-#include "macro.h"
 #include "memory-util.h"
+#include "random-util.h"
+#include "recovery-key.h"
 
 const char modhex_alphabet[16] = {
         'c', 'b', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'n', 'r', 't', 'u', 'v'
@@ -29,24 +27,24 @@ int normalize_recovery_key(const char *password, char **ret) {
 
         l = strlen(password);
         if (!IN_SET(l,
-                    MODHEX_RAW_LENGTH*2,          /* syntax without dashes */
+                    RECOVERY_KEY_MODHEX_RAW_LENGTH*2,          /* syntax without dashes */
-                    MODHEX_FORMATTED_LENGTH-1))   /* syntax with dashes */
+                    RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1))   /* syntax with dashes */
                 return -EINVAL;
 
-        mangled = new(char, MODHEX_FORMATTED_LENGTH);
+        mangled = new(char, RECOVERY_KEY_MODHEX_FORMATTED_LENGTH);
         if (!mangled)
                 return -ENOMEM;
 
-        for (size_t i = 0, j = 0; i < MODHEX_RAW_LENGTH; i++) {
+        for (size_t i = 0, j = 0; i < RECOVERY_KEY_MODHEX_RAW_LENGTH; i++) {
                 size_t k;
                 int a, b;
 
-                if (l == MODHEX_RAW_LENGTH*2)
+                if (l == RECOVERY_KEY_MODHEX_RAW_LENGTH*2)
                         /* Syntax without dashes */
                         k = i * 2;
                 else {
                         /* Syntax with dashes */
-                        assert(l == MODHEX_FORMATTED_LENGTH-1);
+                        assert(l == RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1);
                         k = i * 2 + i / 4;
 
                         if (i > 0 && i % 4 == 0 && password[k-1] != '-')
@@ -67,8 +65,42 @@ int normalize_recovery_key(const char *password, char **ret) {
                         mangled[j++] = '-';
         }
 
-        mangled[MODHEX_FORMATTED_LENGTH-1] = 0;
+        mangled[RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1] = 0;
 
         *ret = TAKE_PTR(mangled);
         return 0;
 }
+
+int make_recovery_key(char **ret) {
+        _cleanup_(erase_and_freep) char *formatted = NULL;
+        _cleanup_(erase_and_freep) uint8_t *key = NULL;
+        int r;
+
+        assert(ret);
+
+        key = new(uint8_t, RECOVERY_KEY_MODHEX_RAW_LENGTH);
+        if (!key)
+                return -ENOMEM;
+
+        r = genuine_random_bytes(key, RECOVERY_KEY_MODHEX_RAW_LENGTH, RANDOM_BLOCK);
+        if (r < 0)
+                return r;
+
+        /* Let's now format it as 64 modhex chars, and after each 8 chars insert a dash */
+        formatted = new(char, RECOVERY_KEY_MODHEX_FORMATTED_LENGTH);
+        if (!formatted)
+                return -ENOMEM;
+
+        for (size_t i = 0, j = 0; i < RECOVERY_KEY_MODHEX_RAW_LENGTH; i++) {
+                formatted[j++] = modhex_alphabet[key[i] >> 4];
+                formatted[j++] = modhex_alphabet[key[i] & 0xF];
+
+                if (i % 4 == 3)
+                        formatted[j++] = '-';
+        }
+
+        formatted[RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1] = 0;
+
+        *ret = TAKE_PTR(formatted);
+        return 0;
+}

src/basic/recovery-key.h

@@ -2,10 +2,12 @@
 #pragma once
 
 /* 256 bit keys = 32 bytes */
-#define MODHEX_RAW_LENGTH 32
+#define RECOVERY_KEY_MODHEX_RAW_LENGTH 32
 
 /* Formatted as sequences of 64 modhex characters, with dashes inserted after multiples of 8 chars (incl. trailing NUL) */
-#define MODHEX_FORMATTED_LENGTH (MODHEX_RAW_LENGTH*2/8*9)
+#define RECOVERY_KEY_MODHEX_FORMATTED_LENGTH (RECOVERY_KEY_MODHEX_RAW_LENGTH*2/8*9)
+
+int make_recovery_key(char **ret);
 
 extern const char modhex_alphabet[16];
 

src/home/homectl-recovery-key.c

@@ -5,46 +5,12 @@
 #include "libcrypt-util.h"
 #include "locale-util.h"
 #include "memory-util.h"
-#include "modhex.h"
 #include "qrcode-util.h"
 #include "random-util.h"
+#include "recovery-key.h"
 #include "strv.h"
 #include "terminal-util.h"
 
-static int make_recovery_key(char **ret) {
-        _cleanup_(erase_and_freep) char *formatted = NULL;
-        _cleanup_(erase_and_freep) uint8_t *key = NULL;
-        int r;
-
-        assert(ret);
-
-        key = new(uint8_t, MODHEX_RAW_LENGTH);
-        if (!key)
-                return log_oom();
-
-        r = genuine_random_bytes(key, MODHEX_RAW_LENGTH, RANDOM_BLOCK);
-        if (r < 0)
-                return log_error_errno(r, "Failed to gather entropy for recovery key: %m");
-
-        /* Let's now format it as 64 modhex chars, and after each 8 chars insert a dash */
-        formatted = new(char, MODHEX_FORMATTED_LENGTH);
-        if (!formatted)
-                return log_oom();
-
-        for (size_t i = 0, j = 0; i < MODHEX_RAW_LENGTH; i++) {
-                formatted[j++] = modhex_alphabet[key[i] >> 4];
-                formatted[j++] = modhex_alphabet[key[i] & 0xF];
-
-                if (i % 4 == 3)
-                        formatted[j++] = '-';
-        }
-
-        formatted[MODHEX_FORMATTED_LENGTH-1] = 0;
-
-        *ret = TAKE_PTR(formatted);
-        return 0;
-}
-
 static int add_privileged(JsonVariant **v, const char *hashed) {
         _cleanup_(json_variant_unrefp) JsonVariant *e = NULL, *w = NULL, *l = NULL;
         int r;
@@ -144,7 +110,7 @@ int identity_add_recovery_key(JsonVariant **v) {
         /* First, let's generate a secret key  */
         r = make_recovery_key(&password);
         if (r < 0)
-                return r;
+                return log_error_errno(r, "Failed to generate recovery key: %m");
 
         /* Let's UNIX hash it */
         r = hash_password(password, &hashed);

src/home/homework.c

@@ -21,9 +21,9 @@
 #include "main-func.h"
 #include "memory-util.h"
 #include "missing_magic.h"
-#include "modhex.h"
 #include "mount-util.h"
 #include "path-util.h"
+#include "recovery-key.h"
 #include "rm-rf.h"
 #include "stat-util.h"
 #include "strv.h"

src/home/meson.build

@@ -19,8 +19,6 @@ systemd_homework_sources = files('''
         homework-quota.h
         homework.c
         homework.h
-        modhex.c
-        modhex.h
         user-record-util.c
         user-record-util.h
 '''.split())
@@ -52,8 +50,6 @@ systemd_homed_sources = files('''
         homed-varlink.c
         homed-varlink.h
         homed.c
-        modhex.c
-        modhex.h
         user-record-pwquality.c
         user-record-pwquality.h
         user-record-sign.c
@@ -80,8 +76,6 @@ homectl_sources = files('''
         homectl-recovery-key.c
         homectl-recovery-key.h
         homectl.c
-        modhex.c
-        modhex.h
         user-record-pwquality.c
         user-record-pwquality.h
         user-record-util.c
@@ -92,8 +86,6 @@ pam_systemd_home_sym = 'src/home/pam_systemd_home.sym'
 pam_systemd_home_c = files('''
         home-util.c
         home-util.h
-        modhex.c
-        modhex.h
         pam_systemd_home.c
         user-record-util.c
         user-record-util.h
@@ -112,11 +104,3 @@ if conf.get('ENABLE_HOMED') == 1
                              install_dir : pkgsysconfdir)
         endif
 endif
-
-tests += [
-        [['src/home/test-modhex.c',
-          'src/home/modhex.c',
-          'src/home/modhex.h'],
-         [],
-         []],
-]

src/home/user-record-util.c

@@ -7,7 +7,7 @@
 #include "id128-util.h"
 #include "libcrypt-util.h"
 #include "memory-util.h"
-#include "modhex.h"
+#include "recovery-key.h"
 #include "mountpoint-util.h"
 #include "path-util.h"
 #include "stat-util.h"

src/test/meson.build

@@ -212,6 +212,10 @@ tests += [
          [],
          []],
 
+        [['src/test/test-modhex.c'],
+         [],
+         []],
+
         [['src/test/test-libmount.c'],
          [],
          [threads,

src/test/test-modhex.c

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include "modhex.h"
+#include "recovery-key.h"
 #include "alloc-util.h"
 #include "string-util.h"