[PATCH v4 5/7] cryptodisk: Refactor password input out of crypto dev modules into cryptodisk

[Glenn Washburn]

The crypto device modules should only be setting up the crypto devices and
not getting user input. This has the added benefit of simplifying the code
such that three essentially duplicate pieces of code are merged into one.

Add documentation of passphrase option for cryptomount as it is now usable.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 docs/grub.texi              |  9 ++++--
 grub-core/disk/cryptodisk.c | 55 ++++++++++++++++++++++++++++++-------
 grub-core/disk/geli.c       | 26 ++++--------------
 grub-core/disk/luks.c       | 27 +++---------------
 grub-core/disk/luks2.c      | 26 ++++--------------
 include/grub/cryptodisk.h   |  1 +
 6 files changed, 66 insertions(+), 78 deletions(-)

diff --git a/docs/grub.texi b/docs/grub.texi
index 99d0a0149..e0a309574 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -4307,13 +4307,16 @@ Alias for @code{hashsum --hash crc32 arg @dots{}}. See 
command @command{hashsum}
 @node cryptomount
 @subsection cryptomount
 
-@deffn Command cryptomount device|@option{-u} uuid|@option{-a}|@option{-b}
-Setup access to encrypted device. If necessary, passphrase
-is requested interactively. Option @var{device} configures specific grub device
+@deffn Command cryptomount [@option{-p} password] device|@option{-u} 
uuid|@option{-a}|@option{-b}
+Setup access to encrypted device. If @option{-p} is not given, a passphrase
+is requested interactively. Otherwise, the given @var{password} will be used 
and
+no passphrase will be requested interactively.
+Option @var{device} configures specific grub device
 (@pxref{Naming convention}); option @option{-u} @var{uuid} configures device
 with specified @var{uuid}; option @option{-a} configures all detected encrypted
 devices; option @option{-b} configures all geli containers that have boot flag 
set.
 
+
 GRUB suports devices encrypted using LUKS, LUKS2 and geli. Note that necessary
 modules (@var{luks}, @var{luks2} and @var{geli}) have to be loaded manually
 before this command can be used. For LUKS2 only the PBKDF2 key derivation
diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 28b61bcb8..b1f127e83 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -1001,9 +1001,11 @@ grub_cryptodisk_scan_device_real (const char *name,
                                  grub_disk_t source,
                                  grub_cryptomount_args_t cargs)
 {
-  grub_err_t err;
+  grub_err_t ret = GRUB_ERR_NONE;
   grub_cryptodisk_t dev;
   grub_cryptodisk_dev_t cr;
+  int askpass = 0;
+  char *part = NULL;
 
   dev = grub_cryptodisk_get_by_source_disk (source);
 
@@ -1022,19 +1024,52 @@ grub_cryptodisk_scan_device_real (const char *name,
       return grub_errno;
     if (!dev)
       continue;
-    
-    err = cr->recover_key (source, dev, cargs);
-    if (err)
-    {
-      cryptodisk_close (dev);
-      return err;
-    }
+
+    if (!cargs->key_len)
+      {
+       /* Get the passphrase from the user, if no key data. */
+       askpass = 1;
+       if (source->partition != NULL)
+         part = grub_partition_get_name (source->partition);
+       grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
+                    source->partition != NULL ? "," : "",
+                    part != NULL ? part : "",
+                    dev->uuid);
+       grub_free (part);
+
+       cargs->key_data = grub_malloc (GRUB_CRYPTODISK_MAX_PASSPHRASE);
+       if (cargs->key_data == NULL)
+         return grub_errno;
+
+       if (!grub_password_get ((char *) cargs->key_data, 
GRUB_CRYPTODISK_MAX_PASSPHRASE))
+         {
+           ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "passphrase not supplied");
+           goto error;
+         }
+       cargs->key_len = grub_strlen ((char *) cargs->key_data);
+      }
+
+    ret = cr->recover_key (source, dev, cargs);
+    if (ret != GRUB_ERR_NONE)
+      goto error;
 
     grub_cryptodisk_insert (dev, name, source);
 
-    return GRUB_ERR_NONE;
+    goto cleanup;
   }
-  return grub_error (GRUB_ERR_BAD_MODULE, "no cryptodisk module can handle 
this device");
+  ret = grub_error (GRUB_ERR_BAD_MODULE, "no cryptodisk module can handle this 
device");
+  goto cleanup;
+
+ error:
+  cryptodisk_close (dev);
+
+ cleanup:
+  if (askpass)
+    {
+      cargs->key_len = 0;
+      grub_free (cargs->key_data);
+    }
+  return ret;
 }
 
 #ifdef GRUB_UTIL
diff --git a/grub-core/disk/geli.c b/grub-core/disk/geli.c
index 777da3a05..7299a47d1 100644
--- a/grub-core/disk/geli.c
+++ b/grub-core/disk/geli.c
@@ -135,8 +135,6 @@ const char *algorithms[] = {
   [0x16] = "aes"
 };
 
-#define MAX_PASSPHRASE 256
-
 static gcry_err_code_t
 geli_rekey (struct grub_cryptodisk *dev, grub_uint64_t zoneno)
 {
@@ -406,17 +404,14 @@ recover_key (grub_disk_t source, grub_cryptodisk_t dev, 
grub_cryptomount_args_t
   grub_uint8_t verify_key[GRUB_CRYPTO_MAX_MDLEN];
   grub_uint8_t zero[GRUB_CRYPTO_MAX_CIPHER_BLOCKSIZE];
   grub_uint8_t geli_cipher_key[64];
-  char passphrase[MAX_PASSPHRASE] = "";
   unsigned i;
   gcry_err_code_t gcry_err;
   struct grub_geli_phdr header;
-  char *tmp;
   grub_disk_addr_t sector;
   grub_err_t err;
 
-  /* Keyfiles are not implemented yet */
-  if (cargs->key_data != NULL || cargs->key_len)
-     return GRUB_ERR_NOT_IMPLEMENTED_YET;
+  if (cargs->key_data == NULL || cargs->key_len == 0)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "no key data");
 
   if (dev->cipher->cipher->blocksize > GRUB_CRYPTO_MAX_CIPHER_BLOCKSIZE)
     return grub_error (GRUB_ERR_BUG, "cipher block is too long");
@@ -438,23 +433,12 @@ recover_key (grub_disk_t source, grub_cryptodisk_t dev, 
grub_cryptomount_args_t
 
   grub_puts_ (N_("Attempting to decrypt master key..."));
 
-  /* Get the passphrase from the user.  */
-  tmp = NULL;
-  if (source->partition)
-    tmp = grub_partition_get_name (source->partition);
-  grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
-               source->partition ? "," : "", tmp ? : "",
-               dev->uuid);
-  grub_free (tmp);
-  if (!grub_password_get (passphrase, MAX_PASSPHRASE))
-    return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
-
   /* Calculate the PBKDF2 of the user supplied passphrase.  */
   if (grub_le_to_cpu32 (header.niter) != 0)
     {
       grub_uint8_t pbkdf_key[64];
-      gcry_err = grub_crypto_pbkdf2 (dev->hash, (grub_uint8_t *) passphrase,
-                                    grub_strlen (passphrase),
+      gcry_err = grub_crypto_pbkdf2 (dev->hash, cargs->key_data,
+                                    cargs->key_len,
                                     header.salt,
                                     sizeof (header.salt),
                                     grub_le_to_cpu32 (header.niter),
@@ -477,7 +461,7 @@ recover_key (grub_disk_t source, grub_cryptodisk_t dev, 
grub_cryptomount_args_t
        return grub_crypto_gcry_error (GPG_ERR_OUT_OF_MEMORY);
 
       grub_crypto_hmac_write (hnd, header.salt, sizeof (header.salt));
-      grub_crypto_hmac_write (hnd, passphrase, grub_strlen (passphrase));
+      grub_crypto_hmac_write (hnd, cargs->key_data, cargs->key_len);
 
       gcry_err = grub_crypto_hmac_fini (hnd, geomkey);
       if (gcry_err)
diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
index c5858fcf8..39a7af6a4 100644
--- a/grub-core/disk/luks.c
+++ b/grub-core/disk/luks.c
@@ -29,8 +29,6 @@
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
-#define MAX_PASSPHRASE 256
-
 #define LUKS_KEY_ENABLED  0x00AC71F3
 
 /* On disk LUKS header */
@@ -158,17 +156,14 @@ luks_recover_key (grub_disk_t source,
   struct grub_luks_phdr header;
   grub_size_t keysize;
   grub_uint8_t *split_key = NULL;
-  char passphrase[MAX_PASSPHRASE] = "";
   grub_uint8_t candidate_digest[sizeof (header.mkDigest)];
   unsigned i;
   grub_size_t length;
   grub_err_t err;
   grub_size_t max_stripes = 1;
-  char *tmp;
 
-  /* Keyfiles are not implemented yet */
-  if (cargs->key_data != NULL || cargs->key_len)
-     return GRUB_ERR_NOT_IMPLEMENTED_YET;
+  if (cargs->key_data == NULL || cargs->key_len == 0)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "no key data");
 
   err = grub_disk_read (source, 0, 0, sizeof (header), &header);
   if (err)
@@ -188,20 +183,6 @@ luks_recover_key (grub_disk_t source,
   if (!split_key)
     return grub_errno;
 
-  /* Get the passphrase from the user.  */
-  tmp = NULL;
-  if (source->partition)
-    tmp = grub_partition_get_name (source->partition);
-  grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
-              source->partition ? "," : "", tmp ? : "",
-              dev->uuid);
-  grub_free (tmp);
-  if (!grub_password_get (passphrase, MAX_PASSPHRASE))
-    {
-      grub_free (split_key);
-      return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
-    }
-
   /* Try to recover master key from each active keyslot.  */
   for (i = 0; i < ARRAY_SIZE (header.keyblock); i++)
     {
@@ -216,8 +197,8 @@ luks_recover_key (grub_disk_t source,
       grub_dprintf ("luks", "Trying keyslot %d\n", i);
 
       /* Calculate the PBKDF2 of the user supplied passphrase.  */
-      gcry_err = grub_crypto_pbkdf2 (dev->hash, (grub_uint8_t *) passphrase,
-                                    grub_strlen (passphrase),
+      gcry_err = grub_crypto_pbkdf2 (dev->hash, cargs->key_data,
+                                    cargs->key_len,
                                     header.keyblock[i].passwordSalt,
                                     sizeof (header.keyblock[i].passwordSalt),
                                     grub_be_to_cpu32 (header.keyblock[i].
diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index 2cbec8acc..e6f9a22f8 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -35,8 +35,6 @@ GRUB_MOD_LICENSE ("GPLv3+");
 #define LUKS_MAGIC_1ST "LUKS\xBA\xBE"
 #define LUKS_MAGIC_2ND "SKUL\xBA\xBE"
 
-#define MAX_PASSPHRASE 256
-
 enum grub_luks2_kdf_type
 {
   LUKS2_KDF_TYPE_ARGON2I,
@@ -549,8 +547,8 @@ luks2_recover_key (grub_disk_t source,
                   grub_cryptomount_args_t cargs)
 {
   grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
-  char passphrase[MAX_PASSPHRASE], cipher[32];
-  char *json_header = NULL, *part = NULL, *ptr;
+  char cipher[32];
+  char *json_header = NULL, *ptr;
   grub_size_t candidate_key_len = 0, json_idx, size;
   grub_luks2_header_t header;
   grub_luks2_keyslot_t keyslot;
@@ -560,9 +558,8 @@ luks2_recover_key (grub_disk_t source,
   grub_json_t *json = NULL, keyslots;
   grub_err_t ret;
 
-  /* Keyfiles are not implemented yet */
-  if (cargs->key_data != NULL || cargs->key_len)
-     return GRUB_ERR_NOT_IMPLEMENTED_YET;
+  if (cargs->key_data == NULL || cargs->key_len == 0)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "no key data");
 
   ret = luks2_read_header (source, &header);
   if (ret)
@@ -589,18 +586,6 @@ luks2_recover_key (grub_disk_t source,
       goto err;
     }
 
-  /* Get the passphrase from the user. */
-  if (source->partition)
-    part = grub_partition_get_name (source->partition);
-  grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
-               source->partition ? "," : "", part ? : "",
-               crypt->uuid);
-  if (!grub_password_get (passphrase, MAX_PASSPHRASE))
-    {
-      ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
-      goto err;
-    }
-
   if (grub_json_getvalue (&keyslots, json, "keyslots") ||
       grub_json_getsize (&size, &keyslots))
     {
@@ -725,7 +710,7 @@ luks2_recover_key (grub_disk_t source,
        }
 
       ret = luks2_decrypt_key (candidate_key, source, crypt, &keyslot,
-                              (const grub_uint8_t *) passphrase, grub_strlen 
(passphrase));
+                              cargs->key_data, cargs->key_len);
       if (ret)
        {
          grub_dprintf ("luks2", "Decryption with keyslot \"%" 
PRIuGRUB_UINT64_T "\" failed: %s\n",
@@ -777,7 +762,6 @@ luks2_recover_key (grub_disk_t source,
     }
 
  err:
-  grub_free (part);
   grub_free (json_header);
   grub_json_free (json);
   return ret;
diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h
index 282f8ac45..5bd970692 100644
--- a/include/grub/cryptodisk.h
+++ b/include/grub/cryptodisk.h
@@ -59,6 +59,7 @@ typedef enum
 #define GRUB_CRYPTODISK_GF_LOG_BYTES (GRUB_CRYPTODISK_GF_LOG_SIZE - 3)
 #define GRUB_CRYPTODISK_GF_BYTES (1U << GRUB_CRYPTODISK_GF_LOG_BYTES)
 #define GRUB_CRYPTODISK_MAX_KEYLEN 128
+#define GRUB_CRYPTODISK_MAX_PASSPHRASE 256
 
 struct grub_cryptodisk;
 
-- 
2.27.0