[PATCH v6 3/6] cryptodisk: enable the backends to implement detached headers

[Denis 'GNUtoo' Carikli]

From: John Lane <john@lane.uk.net>

Signed-off-by: John Lane <john@lane.uk.net>
GNUtoo@cyberdimension.org: rebase, patch split, small fixes, commit message
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Reviewed-by: Patrick Steinhardt <ps@pks.im>
---
ChangeLog since v4:
- Added Reviewed-by tag
ChangeLog since v5:
- No changes
---
 grub-core/disk/cryptodisk.c | 24 ++++++++++++++++++++----
 grub-core/disk/geli.c       | 15 +++++++++++++--
 grub-core/disk/luks.c       | 14 +++++++++++---
 grub-core/disk/luks2.c      | 15 ++++++++++++---
 include/grub/cryptodisk.h   |  6 ++++--
 include/grub/file.h         |  2 ++
 6 files changed, 62 insertions(+), 14 deletions(-)

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 1897acc4b..6ad2e486e 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -41,6 +41,7 @@ static const struct grub_arg_option options[] =
     /* TRANSLATORS: It's still restricted to cryptodisks only.  */
     {"all", 'a', 0, N_("Mount all."), 0, 0},
     {"boot", 'b', 0, N_("Mount all volumes with `boot' flag set."), 0, 0},
+    {"header", 'H', 0, N_("Read header from file"), 0, ARG_TYPE_STRING},
     {0, 0, 0, 0, 0, 0}
   };
 
@@ -970,6 +971,7 @@ grub_util_cryptodisk_get_uuid (grub_disk_t disk)
 
 static int check_boot, have_it;
 static char *search_uuid;
+static grub_file_t hdr;
 
 static void
 cryptodisk_close (grub_cryptodisk_t dev)
@@ -994,13 +996,13 @@ grub_cryptodisk_scan_device_real (const char *name, 
grub_disk_t source)
 
   FOR_CRYPTODISK_DEVS (cr)
   {
-    dev = cr->scan (source, search_uuid, check_boot);
+    dev = cr->scan (source, search_uuid, check_boot, hdr);
     if (grub_errno)
       return grub_errno;
     if (!dev)
       continue;
     
-    err = cr->recover_key (source, dev);
+    err = cr->recover_key (source, dev, hdr);
     if (err)
     {
       cryptodisk_close (dev);
@@ -1041,7 +1043,7 @@ grub_cryptodisk_cheat_mount (const char *sourcedev, const 
char *cheat)
 
   FOR_CRYPTODISK_DEVS (cr)
   {
-    dev = cr->scan (source, search_uuid, check_boot);
+    dev = cr->scan (source, search_uuid, check_boot, NULL);
     if (grub_errno)
       return grub_errno;
     if (!dev)
@@ -1095,6 +1097,20 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int 
argc, char **args)
   if (argc < 1 && !state[1].set && !state[2].set)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
 
+  if (state[3].set) /* Detached header */
+    {
+      if (state[0].set)
+       return grub_error (GRUB_ERR_BAD_ARGUMENT,
+                          N_("Cannot use UUID lookup with detached header"));
+
+      hdr = grub_file_open (state[3].arg,
+                           GRUB_FILE_TYPE_CRYPTODISK_DETACHED_HEADER);
+      if (!hdr)
+       return grub_errno;
+    }
+  else
+    hdr = NULL;
+
   have_it = 0;
   if (state[0].set)
     {
@@ -1302,7 +1318,7 @@ GRUB_MOD_INIT (cryptodisk)
 {
   grub_disk_dev_register (&grub_cryptodisk_dev);
   cmd = grub_register_extcmd ("cryptomount", grub_cmd_cryptomount, 0,
-                             N_("SOURCE|-u UUID|-a|-b"),
+                             N_("SOURCE|-u UUID|-a|-b|-H file"),
                              N_("Mount a crypto device."), options);
   grub_procfs_register ("luks_script", &luks_script);
 }
diff --git a/grub-core/disk/geli.c b/grub-core/disk/geli.c
index 581631c1d..acd09d874 100644
--- a/grub-core/disk/geli.c
+++ b/grub-core/disk/geli.c
@@ -52,6 +52,7 @@
 #include <grub/dl.h>
 #include <grub/err.h>
 #include <grub/disk.h>
+#include <grub/file.h>
 #include <grub/crypto.h>
 #include <grub/partition.h>
 #include <grub/i18n.h>
@@ -121,6 +122,7 @@ enum
 
 /* FIXME: support version 0.  */
 /* FIXME: support big-endian pre-version-4 volumes.  */
+/* FIXME: support for detached headers.  */
 /* FIXME: support for keyfiles.  */
 /* FIXME: support for HMAC.  */
 const char *algorithms[] = {
@@ -242,7 +244,8 @@ grub_util_get_geli_uuid (const char *dev)
 #endif
 
 static grub_cryptodisk_t
-geli_scan (grub_disk_t disk, const char *check_uuid, int boot_only)
+geli_scan (grub_disk_t disk, const char *check_uuid, int boot_only,
+          grub_file_t hdr)
 {
   grub_cryptodisk_t newdev;
   struct grub_geli_phdr header;
@@ -254,6 +257,10 @@ geli_scan (grub_disk_t disk, const char *check_uuid, int 
boot_only)
   grub_disk_addr_t sector;
   grub_err_t err;
 
+  /* Detached headers are not implemented yet */
+  if (hdr)
+    return NULL;
+
   if (2 * GRUB_MD_SHA256->mdlen + 1 > GRUB_CRYPTODISK_MAX_UUID_LENGTH)
     return NULL;
 
@@ -397,7 +404,7 @@ geli_scan (grub_disk_t disk, const char *check_uuid, int 
boot_only)
 }
 
 static grub_err_t
-geli_recover_key (grub_disk_t source, grub_cryptodisk_t dev)
+geli_recover_key (grub_disk_t source, grub_cryptodisk_t dev, grub_file_t hdr)
 {
   grub_size_t keysize;
   grub_uint8_t digest[GRUB_CRYPTO_MAX_MDLEN];
@@ -413,6 +420,10 @@ geli_recover_key (grub_disk_t source, grub_cryptodisk_t 
dev)
   grub_disk_addr_t sector;
   grub_err_t err;
 
+  /* Detached headers are not implemented yet */
+  if (hdr)
+    return GRUB_ERR_NOT_IMPLEMENTED_YET;
+
   if (dev->cipher->cipher->blocksize > GRUB_CRYPTO_MAX_CIPHER_BLOCKSIZE)
     return grub_error (GRUB_ERR_BUG, "cipher block is too long");
 
diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
index b50f6fd02..685235565 100644
--- a/grub-core/disk/luks.c
+++ b/grub-core/disk/luks.c
@@ -65,7 +65,8 @@ gcry_err_code_t AF_merge (const gcry_md_spec_t * hash, 
grub_uint8_t * src,
                          grub_size_t blocknumbers);
 
 static grub_cryptodisk_t
-luks_scan (grub_disk_t disk, const char *check_uuid, int check_boot)
+luks_scan (grub_disk_t disk, const char *check_uuid, int check_boot,
+          grub_file_t hdr)
 {
   grub_cryptodisk_t newdev;
   const char *iptr;
@@ -77,6 +78,10 @@ luks_scan (grub_disk_t disk, const char *check_uuid, int 
check_boot)
   char hashspec[sizeof (header.hashSpec) + 1];
   grub_err_t err;
 
+  /* Detached headers are not implemented yet */
+  if (hdr)
+    return NULL;
+
   if (check_boot)
     return NULL;
 
@@ -149,8 +154,7 @@ luks_scan (grub_disk_t disk, const char *check_uuid, int 
check_boot)
 }
 
 static grub_err_t
-luks_recover_key (grub_disk_t source,
-                 grub_cryptodisk_t dev)
+luks_recover_key (grub_disk_t source, grub_cryptodisk_t dev, grub_file_t hdr)
 {
   struct grub_luks_phdr header;
   grub_size_t keysize;
@@ -163,6 +167,10 @@ luks_recover_key (grub_disk_t source,
   grub_size_t max_stripes = 1;
   char *tmp;
 
+  /* Detached headers are not implemented yet */
+  if (hdr)
+    return GRUB_ERR_NOT_IMPLEMENTED_YET;
+
   err = grub_disk_read (source, 0, 0, sizeof (header), &header);
   if (err)
     return err;
diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index e3ff7c83d..bc00e8bbc 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -342,11 +342,16 @@ luks2_read_header (grub_disk_t disk, grub_luks2_header_t 
*outhdr)
 }
 
 static grub_cryptodisk_t
-luks2_scan (grub_disk_t disk, const char *check_uuid, int check_boot)
+luks2_scan (grub_disk_t disk, const char *check_uuid, int check_boot,
+           grub_file_t hdr_file)
 {
   grub_cryptodisk_t cryptodisk;
   grub_luks2_header_t header;
 
+  /* Detached headers are not implemented yet */
+  if (hdr_file)
+    return NULL;
+
   if (check_boot)
     return NULL;
 
@@ -523,8 +528,8 @@ luks2_decrypt_key (grub_uint8_t *out_key,
 }
 
 static grub_err_t
-luks2_recover_key (grub_disk_t disk,
-                  grub_cryptodisk_t crypt)
+luks2_recover_key (grub_disk_t disk, grub_cryptodisk_t crypt,
+                  grub_file_t hdr_file)
 {
   grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
   char passphrase[MAX_PASSPHRASE], cipher[32];
@@ -538,6 +543,10 @@ luks2_recover_key (grub_disk_t disk,
   grub_json_t *json = NULL, keyslots;
   grub_err_t ret;
 
+  /* Detached headers are not implemented yet */
+  if (hdr_file)
+    return GRUB_ERR_NOT_IMPLEMENTED_YET;
+
   ret = luks2_read_header (disk, &header);
   if (ret)
     return ret;
diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h
index e1b21e785..e24b1b8cb 100644
--- a/include/grub/cryptodisk.h
+++ b/include/grub/cryptodisk.h
@@ -20,6 +20,7 @@
 #define GRUB_CRYPTODISK_HEADER 1
 
 #include <grub/disk.h>
+#include <grub/file.h>
 #include <grub/crypto.h>
 #include <grub/list.h>
 #ifdef GRUB_UTIL
@@ -107,8 +108,9 @@ struct grub_cryptodisk_dev
   struct grub_cryptodisk_dev **prev;
 
   grub_cryptodisk_t (*scan) (grub_disk_t disk, const char *check_uuid,
-                            int boot_only);
-  grub_err_t (*recover_key) (grub_disk_t disk, grub_cryptodisk_t dev);
+                            int boot_only, grub_file_t hdr);
+  grub_err_t (*recover_key) (grub_disk_t disk, grub_cryptodisk_t dev,
+                            grub_file_t hdr);
 };
 typedef struct grub_cryptodisk_dev *grub_cryptodisk_dev_t;
 
diff --git a/include/grub/file.h b/include/grub/file.h
index 31567483c..a7d7be853 100644
--- a/include/grub/file.h
+++ b/include/grub/file.h
@@ -90,6 +90,8 @@ enum grub_file_type
     GRUB_FILE_TYPE_FONT,
     /* File holding encryption key for encrypted ZFS.  */
     GRUB_FILE_TYPE_ZFS_ENCRYPTION_KEY,
+    /* File holiding the encryption metadata header */
+    GRUB_FILE_TYPE_CRYPTODISK_DETACHED_HEADER,
     /* File we open n grub-fstest.  */
     GRUB_FILE_TYPE_FSTEST,
     /* File we open n grub-mount.  */
-- 
2.28.0