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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /fs/ext4/ext4_crypto.h
Initial import
Diffstat (limited to 'fs/ext4/ext4_crypto.h')
-rw-r--r--fs/ext4/ext4_crypto.h156
1 files changed, 156 insertions, 0 deletions
diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
new file mode 100644
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+++ b/fs/ext4/ext4_crypto.h
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+/*
+ * 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 */