From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 fs/ext4/ext4_crypto.h | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 fs/ext4/ext4_crypto.h

(limited to 'fs/ext4/ext4_crypto.h')

diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
new file mode 100644
index 000000000..d75159c10
--- /dev/null
+++ b/fs/ext4/ext4_crypto.h
@@ -0,0 +1,156 @@
+/*
+ * linux/fs/ext4/ext4_crypto.h
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This contains encryption header content for ext4
+ *
+ * Written by Michael Halcrow, 2015.
+ */
+
+#ifndef _EXT4_CRYPTO_H
+#define _EXT4_CRYPTO_H
+
+#include <linux/fs.h>
+
+#define EXT4_KEY_DESCRIPTOR_SIZE 8
+
+/* Policy provided via an ioctl on the topmost directory */
+struct ext4_encryption_policy {
+	char version;
+	char contents_encryption_mode;
+	char filenames_encryption_mode;
+	char flags;
+	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
+} __attribute__((__packed__));
+
+#define EXT4_ENCRYPTION_CONTEXT_FORMAT_V1 1
+#define EXT4_KEY_DERIVATION_NONCE_SIZE 16
+
+#define EXT4_POLICY_FLAGS_PAD_4		0x00
+#define EXT4_POLICY_FLAGS_PAD_8		0x01
+#define EXT4_POLICY_FLAGS_PAD_16	0x02
+#define EXT4_POLICY_FLAGS_PAD_32	0x03
+#define EXT4_POLICY_FLAGS_PAD_MASK	0x03
+#define EXT4_POLICY_FLAGS_VALID		0x03
+
+/**
+ * Encryption context for inode
+ *
+ * Protector format:
+ *  1 byte: Protector format (1 = this version)
+ *  1 byte: File contents encryption mode
+ *  1 byte: File names encryption mode
+ *  1 byte: Reserved
+ *  8 bytes: Master Key descriptor
+ *  16 bytes: Encryption Key derivation nonce
+ */
+struct ext4_encryption_context {
+	char format;
+	char contents_encryption_mode;
+	char filenames_encryption_mode;
+	char flags;
+	char master_key_descriptor[EXT4_KEY_DESCRIPTOR_SIZE];
+	char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
+} __attribute__((__packed__));
+
+/* Encryption parameters */
+#define EXT4_XTS_TWEAK_SIZE 16
+#define EXT4_AES_128_ECB_KEY_SIZE 16
+#define EXT4_AES_256_GCM_KEY_SIZE 32
+#define EXT4_AES_256_CBC_KEY_SIZE 32
+#define EXT4_AES_256_CTS_KEY_SIZE 32
+#define EXT4_AES_256_XTS_KEY_SIZE 64
+#define EXT4_MAX_KEY_SIZE 64
+
+#define EXT4_KEY_DESC_PREFIX "ext4:"
+#define EXT4_KEY_DESC_PREFIX_SIZE 5
+
+struct ext4_encryption_key {
+	uint32_t mode;
+	char raw[EXT4_MAX_KEY_SIZE];
+	uint32_t size;
+};
+
+#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL             0x00000001
+#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL     0x00000002
+
+struct ext4_crypto_ctx {
+	struct crypto_tfm *tfm;         /* Crypto API context */
+	struct page *bounce_page;       /* Ciphertext page on write path */
+	struct page *control_page;      /* Original page on write path */
+	struct bio *bio;                /* The bio for this context */
+	struct work_struct work;        /* Work queue for read complete path */
+	struct list_head free_list;     /* Free list */
+	int flags;                      /* Flags */
+	int mode;                       /* Encryption mode for tfm */
+};
+
+struct ext4_completion_result {
+	struct completion completion;
+	int res;
+};
+
+#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
+	struct ext4_completion_result ecr = { \
+		COMPLETION_INITIALIZER((ecr).completion), 0 }
+
+static inline int ext4_encryption_key_size(int mode)
+{
+	switch (mode) {
+	case EXT4_ENCRYPTION_MODE_AES_256_XTS:
+		return EXT4_AES_256_XTS_KEY_SIZE;
+	case EXT4_ENCRYPTION_MODE_AES_256_GCM:
+		return EXT4_AES_256_GCM_KEY_SIZE;
+	case EXT4_ENCRYPTION_MODE_AES_256_CBC:
+		return EXT4_AES_256_CBC_KEY_SIZE;
+	case EXT4_ENCRYPTION_MODE_AES_256_CTS:
+		return EXT4_AES_256_CTS_KEY_SIZE;
+	default:
+		BUG();
+	}
+	return 0;
+}
+
+#define EXT4_FNAME_NUM_SCATTER_ENTRIES	4
+#define EXT4_CRYPTO_BLOCK_SIZE		16
+#define EXT4_FNAME_CRYPTO_DIGEST_SIZE	32
+
+struct ext4_str {
+	unsigned char *name;
+	u32 len;
+};
+
+struct ext4_fname_crypto_ctx {
+	u32 lim;
+	char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE];
+	struct crypto_ablkcipher *ctfm;
+	struct crypto_hash *htfm;
+	struct page *workpage;
+	struct ext4_encryption_key key;
+	unsigned flags : 8;
+	unsigned has_valid_key : 1;
+	unsigned ctfm_key_is_ready : 1;
+};
+
+/**
+ * For encrypted symlinks, the ciphertext length is stored at the beginning
+ * of the string in little-endian format.
+ */
+struct ext4_encrypted_symlink_data {
+	__le16 len;
+	char encrypted_path[1];
+} __attribute__((__packed__));
+
+/**
+ * This function is used to calculate the disk space required to
+ * store a filename of length l in encrypted symlink format.
+ */
+static inline u32 encrypted_symlink_data_len(u32 l)
+{
+	if (l < EXT4_CRYPTO_BLOCK_SIZE)
+		l = EXT4_CRYPTO_BLOCK_SIZE;
+	return (l + sizeof(struct ext4_encrypted_symlink_data) - 1);
+}
+
+#endif	/* _EXT4_CRYPTO_H */
-- 
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