diff options
| -rw-r--r-- | fs/ext4/Makefile | 2 | ||||
| -rw-r--r-- | fs/ext4/crypto_key.c | 162 | ||||
| -rw-r--r-- | fs/ext4/ext4.h | 13 | ||||
| -rw-r--r-- | fs/ext4/ext4_crypto.h | 3 |
4 files changed, 179 insertions, 1 deletions
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile index 1b1c561..4e5af21 100644 --- a/fs/ext4/Makefile +++ b/fs/ext4/Makefile @@ -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_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 diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c new file mode 100644 index 0000000..572bd97 --- /dev/null +++ b/fs/ext4/crypto_key.c @@ -0,0 +1,162 @@ +/* + * 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); +} diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 71619ef..99a2d67 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2078,6 +2078,19 @@ static inline int ext4_sb_has_crypto(struct super_block *sb) } #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 */ extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *, struct file *, diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h index 9d5d2e5..6a7c0c0 100644 --- a/fs/ext4/ext4_crypto.h +++ b/fs/ext4/ext4_crypto.h @@ -55,6 +55,9 @@ struct ext4_encryption_context { #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]; |
