[PATCH v2 1/3] cryptodisk: make the password getter and additional argument to recover_key

[James Bottomley <jejb@linux.ibm.com>]

For AMD SEV environments, the grub boot password has to be retrieved
from a given memory location rather than prompted for.  This means
that the standard password getter needs to be replaced with one that
gets the passphrase from the SEV area and uses that instead.  Adding
the password getter as a passed in argument to recover_key() makes
this possible.

Signed-off-by: James Bottomley <jejb@linux.ibm.com>

---

v2: add conditional prompting to geli.c
---
 grub-core/disk/cryptodisk.c |  2 +-
 grub-core/disk/geli.c       | 12 +++++++-----
 grub-core/disk/luks.c       | 12 +++++++-----
 grub-core/disk/luks2.c      | 12 +++++++-----
 include/grub/cryptodisk.h   |  6 +++++-
 5 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index a3d672f68..682f5a55d 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -997,7 +997,7 @@ grub_cryptodisk_scan_device_real (const char *name, grub_disk_t source)
     if (!dev)
       continue;
     
-    err = cr->recover_key (source, dev);
+    err = cr->recover_key (source, dev, grub_password_get);
     if (err)
     {
       cryptodisk_close (dev);
diff --git a/grub-core/disk/geli.c b/grub-core/disk/geli.c
index e9d23299a..3fece3f4a 100644
--- a/grub-core/disk/geli.c
+++ b/grub-core/disk/geli.c
@@ -398,7 +398,8 @@ configure_ciphers (grub_disk_t disk, const char *check_uuid,
 }
 
 static grub_err_t
-recover_key (grub_disk_t source, grub_cryptodisk_t dev)
+recover_key (grub_disk_t source, grub_cryptodisk_t dev,
+	     grub_passwd_cb *password_get)
 {
   grub_size_t keysize;
   grub_uint8_t digest[GRUB_CRYPTO_MAX_MDLEN];
@@ -438,11 +439,12 @@ recover_key (grub_disk_t source, grub_cryptodisk_t dev)
   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);
+  if (password_get == grub_password_get)
+    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))
+  if (!password_get (passphrase, MAX_PASSPHRASE))
     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
 
   /* Calculate the PBKDF2 of the user supplied passphrase.  */
diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
index 59702067a..165f4a6bd 100644
--- a/grub-core/disk/luks.c
+++ b/grub-core/disk/luks.c
@@ -152,7 +152,8 @@ configure_ciphers (grub_disk_t disk, const char *check_uuid,
 
 static grub_err_t
 luks_recover_key (grub_disk_t source,
-		  grub_cryptodisk_t dev)
+		  grub_cryptodisk_t dev,
+		  grub_passwd_cb *password_get)
 {
   struct grub_luks_phdr header;
   grub_size_t keysize;
@@ -187,11 +188,12 @@ luks_recover_key (grub_disk_t source,
   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);
+  if (password_get == grub_password_get)
+	  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))
+  if (!password_get (passphrase, MAX_PASSPHRASE))
     {
       grub_free (split_key);
       return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
index 31d7166fc..984182aa9 100644
--- a/grub-core/disk/luks2.c
+++ b/grub-core/disk/luks2.c
@@ -531,7 +531,8 @@ luks2_decrypt_key (grub_uint8_t *out_key,
 
 static grub_err_t
 luks2_recover_key (grub_disk_t disk,
-		   grub_cryptodisk_t crypt)
+		   grub_cryptodisk_t crypt,
+		   grub_passwd_cb *password_get)
 {
   grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
   char passphrase[MAX_PASSPHRASE], cipher[32];
@@ -573,10 +574,11 @@ luks2_recover_key (grub_disk_t disk,
   /* Get the passphrase from the user. */
   if (disk->partition)
     part = grub_partition_get_name (disk->partition);
-  grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), disk->name,
-		disk->partition ? "," : "", part ? : "",
-		crypt->uuid);
-  if (!grub_password_get (passphrase, MAX_PASSPHRASE))
+  if (password_get == grub_password_get)
+    grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), disk->name,
+		  disk->partition ? "," : "", part ? : "",
+		  crypt->uuid);
+  if (!password_get (passphrase, MAX_PASSPHRASE))
     {
       ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
       goto err;
diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h
index e1b21e785..45dae5483 100644
--- a/include/grub/cryptodisk.h
+++ b/include/grub/cryptodisk.h
@@ -101,6 +101,9 @@ struct grub_cryptodisk
 };
 typedef struct grub_cryptodisk *grub_cryptodisk_t;
 
+/* must match prototype for grub_password_get */
+typedef int (grub_passwd_cb)(char buf[], unsigned buf_size);
+
 struct grub_cryptodisk_dev
 {
   struct grub_cryptodisk_dev *next;
@@ -108,7 +111,8 @@ struct grub_cryptodisk_dev
 
   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);
+  grub_err_t (*recover_key) (grub_disk_t disk, grub_cryptodisk_t dev,
+			     grub_passwd_cb *get_password);
 };
 typedef struct grub_cryptodisk_dev *grub_cryptodisk_dev_t;
 
-- 
2.26.2