ext4 crypto: add encryption key management facilities (88bd6ccd) · Commits · e / devices / android_kernel_fairphone_FP3

fs/ext4/Makefile

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -12,4 +12,4 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \

	ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o		ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
	ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o		ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
	ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o		ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o crypto_key.o

fs/ext4/crypto_key.c

0 → 100644

+162 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* linux/fs/ext4/crypto_key.c
			*
			* Copyright (C) 2015, Google, Inc.
			*
			* This contains encryption key functions for ext4
			*
			* Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
			*/

			#include <keys/encrypted-type.h>
			#include <keys/user-type.h>
			#include <linux/random.h>
			#include <linux/scatterlist.h>
			#include <uapi/linux/keyctl.h>

			#include "ext4.h"
			#include "xattr.h"

			static void derive_crypt_complete(struct crypto_async_request *req, int rc)
			{
			struct ext4_completion_result *ecr = req->data;

			if (rc == -EINPROGRESS)
			return;

			ecr->res = rc;
			complete(&ecr->completion);
			}

			/**
			* ext4_derive_key_aes() - Derive a key using AES-128-ECB
			* @deriving_key: Encryption key used for derivatio.
			* @source_key: Source key to which to apply derivation.
			* @derived_key: Derived key.
			*
			* Return: Zero on success; non-zero otherwise.
			*/
			static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
			char source_key[EXT4_AES_256_XTS_KEY_SIZE],
			char derived_key[EXT4_AES_256_XTS_KEY_SIZE])
			{
			int res = 0;
			struct ablkcipher_request *req = NULL;
			DECLARE_EXT4_COMPLETION_RESULT(ecr);
			struct scatterlist src_sg, dst_sg;
			struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
			0);

			if (IS_ERR(tfm)) {
			res = PTR_ERR(tfm);
			tfm = NULL;
			goto out;
			}
			crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
			req = ablkcipher_request_alloc(tfm, GFP_NOFS);
			if (!req) {
			res = -ENOMEM;
			goto out;
			}
			ablkcipher_request_set_callback(req,
			CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
			derive_crypt_complete, &ecr);
			res = crypto_ablkcipher_setkey(tfm, deriving_key,
			EXT4_AES_128_ECB_KEY_SIZE);
			if (res < 0)
			goto out;
			sg_init_one(&src_sg, source_key, EXT4_AES_256_XTS_KEY_SIZE);
			sg_init_one(&dst_sg, derived_key, EXT4_AES_256_XTS_KEY_SIZE);
			ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
			EXT4_AES_256_XTS_KEY_SIZE, NULL);
			res = crypto_ablkcipher_encrypt(req);
			if (res == -EINPROGRESS \|\| res == -EBUSY) {
			BUG_ON(req->base.data != &ecr);
			wait_for_completion(&ecr.completion);
			res = ecr.res;
			}

			out:
			if (req)
			ablkcipher_request_free(req);
			if (tfm)
			crypto_free_ablkcipher(tfm);
			return res;
			}

			/**
			* ext4_generate_encryption_key() - generates an encryption key
			* @inode: The inode to generate the encryption key for.
			*/
			int ext4_generate_encryption_key(struct inode *inode)
			{
			struct ext4_inode_info *ei = EXT4_I(inode);
			struct ext4_encryption_key *crypt_key = &ei->i_encryption_key;
			char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
			(EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];
			struct key *keyring_key = NULL;
			struct ext4_encryption_key *master_key;
			struct ext4_encryption_context ctx;
			struct user_key_payload *ukp;
			int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
			EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
			&ctx, sizeof(ctx));

			if (res != sizeof(ctx)) {
			if (res > 0)
			res = -EINVAL;
			goto out;
			}
			res = 0;

			memcpy(full_key_descriptor, EXT4_KEY_DESC_PREFIX,
			EXT4_KEY_DESC_PREFIX_SIZE);
			sprintf(full_key_descriptor + EXT4_KEY_DESC_PREFIX_SIZE,
			"%*phN", EXT4_KEY_DESCRIPTOR_SIZE,
			ctx.master_key_descriptor);
			full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
			(2 * EXT4_KEY_DESCRIPTOR_SIZE)] = '\0';
			keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
			if (IS_ERR(keyring_key)) {
			res = PTR_ERR(keyring_key);
			keyring_key = NULL;
			goto out;
			}
			BUG_ON(keyring_key->type != &key_type_logon);
			ukp = ((struct user_key_payload *)keyring_key->payload.data);
			if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
			res = -EINVAL;
			goto out;
			}
			master_key = (struct ext4_encryption_key *)ukp->data;

			if (S_ISREG(inode->i_mode))
			crypt_key->mode = ctx.contents_encryption_mode;
			else if (S_ISDIR(inode->i_mode) \|\| S_ISLNK(inode->i_mode))
			crypt_key->mode = ctx.filenames_encryption_mode;
			else {
			printk(KERN_ERR "ext4 crypto: Unsupported inode type.\n");
			BUG();
			}
			crypt_key->size = ext4_encryption_key_size(crypt_key->mode);
			BUG_ON(!crypt_key->size);
			BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
			EXT4_KEY_DERIVATION_NONCE_SIZE);
			BUG_ON(master_key->size != EXT4_AES_256_XTS_KEY_SIZE);
			BUG_ON(crypt_key->size < EXT4_AES_256_CBC_KEY_SIZE);
			res = ext4_derive_key_aes(ctx.nonce, master_key->raw, crypt_key->raw);
			out:
			if (keyring_key)
			key_put(keyring_key);
			if (res < 0)
			crypt_key->mode = EXT4_ENCRYPTION_MODE_INVALID;
			return res;
			}

			int ext4_has_encryption_key(struct inode *inode)
			{
			struct ext4_inode_info *ei = EXT4_I(inode);
			struct ext4_encryption_key *crypt_key = &ei->i_encryption_key;

			return (crypt_key->mode != EXT4_ENCRYPTION_MODE_INVALID);
			}

fs/ext4/ext4.h

+13 −0

Original line number	Original line	Diff line number	Diff line
	@@ -2078,6 +2078,19 @@ static inline int ext4_sb_has_crypto(struct super_block *sb)
	}		}
	#endif		#endif

			/* crypto_key.c */
			int ext4_generate_encryption_key(struct inode *inode);

			#ifdef CONFIG_EXT4_FS_ENCRYPTION
			int ext4_has_encryption_key(struct inode *inode);
			#else
			static inline int ext4_has_encryption_key(struct inode *inode)
			{
			return 0;
			}
			#endif


	/* dir.c */		/* dir.c */
	extern int __ext4_check_dir_entry(const char , unsigned int, struct inode ,		extern int __ext4_check_dir_entry(const char , unsigned int, struct inode ,
	struct file *,		struct file *,

fs/ext4/ext4_crypto.h

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -55,6 +55,9 @@ struct ext4_encryption_context {
	#define EXT4_AES_256_XTS_KEY_SIZE 64		#define EXT4_AES_256_XTS_KEY_SIZE 64
	#define EXT4_MAX_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 {		struct ext4_encryption_key {
	uint32_t mode;		uint32_t mode;
	char raw[EXT4_MAX_KEY_SIZE];		char raw[EXT4_MAX_KEY_SIZE];