Support Speck encryption.

Test: Modified Pixel to support and use Speck encryption, booted.
Bug: 77227248
Change-Id: I1efc54b60e074265914fde764ab4b85798128d67
Merged-In: I1efc54b60e074265914fde764ab4b85798128d67

1 files changed, 14 insertions, 11 deletions

diff --git a/ext4_utils/ext4_crypt.cpp b/ext4_utils/ext4_crypt.cpp
index 6540e514..f392046a 100644
--- a/ext4_utils/ext4_crypt.cpp
+++ b/ext4_utils/ext4_crypt.cpp
@@ -48,6 +48,8 @@ struct ext4_encryption_policy {
 
 #define EXT4_ENCRYPTION_MODE_AES_256_XTS    1
 #define EXT4_ENCRYPTION_MODE_AES_256_CTS    4
+#define EXT4_ENCRYPTION_MODE_SPECK128_256_XTS 7
+#define EXT4_ENCRYPTION_MODE_SPECK128_256_CTS 8
 #define EXT4_ENCRYPTION_MODE_AES_256_HEH    126
 #define EXT4_ENCRYPTION_MODE_PRIVATE        127
 
@@ -109,18 +111,15 @@ static bool is_dir_empty(const char *dirname, bool *is_empty)
 }
 
 static uint8_t e4crypt_get_policy_flags(int filenames_encryption_mode) {
-
-    // With HEH, pad filenames with zeroes to the next 16-byte boundary.  This
-    // is not required, but it's more secure (helps hide the length of
-    // filenames), makes the inputs evenly divisible into blocks which is more
-    // efficient for encryption and decryption, and we had the opportunity to
-    // make a breaking change when introducing a new mode anyway.
-    if (filenames_encryption_mode == EXT4_ENCRYPTION_MODE_AES_256_HEH) {
-        return EXT4_POLICY_FLAGS_PAD_16;
+    if (filenames_encryption_mode == EXT4_ENCRYPTION_MODE_AES_256_CTS) {
+        // Use legacy padding with our original filenames encryption mode.
+        return EXT4_POLICY_FLAGS_PAD_4;
     }
-
-    // Default flags (4-byte padding) for CTS
-    return EXT4_POLICY_FLAGS_PAD_4;
+    // With a new mode we can use the better padding flag without breaking existing devices: pad
+    // filenames with zeroes to the next 16-byte boundary.  This is more secure (helps hide the
+    // length of filenames) and makes the inputs evenly divisible into blocks which is more
+    // efficient for encryption and decryption.
+    return EXT4_POLICY_FLAGS_PAD_16;
 }
 
 static bool e4crypt_policy_set(const char *directory, const char *policy,
@@ -234,6 +233,8 @@ int e4crypt_policy_ensure(const char *directory, const char *policy,
     if (!strcmp(contents_encryption_mode, "software") ||
         !strcmp(contents_encryption_mode, "aes-256-xts")) {
         contents_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+    } else if (!strcmp(contents_encryption_mode, "speck128/256-xts")) {
+        contents_mode = EXT4_ENCRYPTION_MODE_SPECK128_256_XTS;
     } else if (!strcmp(contents_encryption_mode, "ice")) {
         contents_mode = EXT4_ENCRYPTION_MODE_PRIVATE;
     } else {
@@ -244,6 +245,8 @@ int e4crypt_policy_ensure(const char *directory, const char *policy,
 
     if (!strcmp(filenames_encryption_mode, "aes-256-cts")) {
         filenames_mode = EXT4_ENCRYPTION_MODE_AES_256_CTS;
+    } else if (!strcmp(filenames_encryption_mode, "speck128/256-cts")) {
+        filenames_mode = EXT4_ENCRYPTION_MODE_SPECK128_256_CTS;
     } else if (!strcmp(filenames_encryption_mode, "aes-256-heh")) {
         filenames_mode = EXT4_ENCRYPTION_MODE_AES_256_HEH;
     } else {