DivestOS/Patches/LineageOS-18.1/android_system_extras/0001-ext4_pad_filenames.patch

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From da1020cc2923c0a61a3dd55109aa342bd2097c1b Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Wed, 9 Sep 2020 01:53:11 -0400
Subject: [PATCH] pad filenames to 32 bytes instead of 16 or 4 bytes
This was adopted before the earliest stable release of GrapheneOS, so
backwards compatibility is not implemented anymore.
---
libfscrypt/fscrypt.cpp | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/libfscrypt/fscrypt.cpp b/libfscrypt/fscrypt.cpp
index a52ed90c..7852349f 100644
--- a/libfscrypt/fscrypt.cpp
+++ b/libfscrypt/fscrypt.cpp
@@ -228,17 +228,8 @@ bool ParseOptionsForApiLevel(unsigned int first_api_level, const std::string& op
}
}
- // In the original setting of v1 policies and AES-256-CTS we used 4-byte
- // padding of filenames, so retain that on old first_api_levels.
- //
- // For everything else, use 16-byte padding. This is more secure (it helps
- // hide the length of filenames), and it makes the inputs evenly divisible
- // into cipher blocks which is more efficient for encryption and decryption.
- if (!is_gki && options->version == 1 && options->filenames_mode == FSCRYPT_MODE_AES_256_CTS) {
- options->flags |= FSCRYPT_POLICY_FLAGS_PAD_4;
- } else {
- options->flags |= FSCRYPT_POLICY_FLAGS_PAD_16;
- }
+ // GrapheneOS has always used the maximum 32 byte padding.
+ options->flags |= FSCRYPT_POLICY_FLAGS_PAD_32;
// Use DIRECT_KEY for Adiantum, since it's much more efficient but just as
// secure since Android doesn't reuse the same master key for multiple