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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* AEAD: Authenticated Encryption with Associated Data
*
* Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
*/
#ifndef _CRYPTO_AEAD_H
#define _CRYPTO_AEAD_H
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/slab.h>
/**
* DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
*
* The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
* (listed as type "aead" in /proc/crypto)
*
* The most prominent examples for this type of encryption is GCM and CCM.
* However, the kernel supports other types of AEAD ciphers which are defined
* with the following cipher string:
*
* authenc(keyed message digest, block cipher)
*
* For example: authenc(hmac(sha256), cbc(aes))
*
* The example code provided for the symmetric key cipher operation
* applies here as well. Naturally all *skcipher* symbols must be exchanged
* the *aead* pendants discussed in the following. In addition, for the AEAD
* operation, the aead_request_set_ad function must be used to set the
* pointer to the associated data memory location before performing the
* encryption or decryption operation. In case of an encryption, the associated
* data memory is filled during the encryption operation. For decryption, the
* associated data memory must contain data that is used to verify the integrity
* of the decrypted data. Another deviation from the asynchronous block cipher
* operation is that the caller should explicitly check for -EBADMSG of the
* crypto_aead_decrypt. That error indicates an authentication error, i.e.
* a breach in the integrity of the message. In essence, that -EBADMSG error
* code is the key bonus an AEAD cipher has over "standard" block chaining
* modes.
*
* Memory Structure:
*
* To support the needs of the most prominent user of AEAD ciphers, namely
* IPSEC, the AEAD ciphers have a special memory layout the caller must adhere
* to.
*
* The scatter list pointing to the input data must contain:
*
* * for RFC4106 ciphers, the concatenation of
* associated authentication data || IV || plaintext or ciphertext. Note, the
* same IV (buffer) is also set with the aead_request_set_crypt call. Note,
* the API call of aead_request_set_ad must provide the length of the AAD and
* the IV. The API call of aead_request_set_crypt only points to the size of
* the input plaintext or ciphertext.
*
* * for "normal" AEAD ciphers, the concatenation of
* associated authentication data || plaintext or ciphertext.
*
* It is important to note that if multiple scatter gather list entries form
* the input data mentioned above, the first entry must not point to a NULL
* buffer. If there is any potential where the AAD buffer can be NULL, the
* calling code must contain a precaution to ensure that this does not result
* in the first scatter gather list entry pointing to a NULL buffer.
*/
struct crypto_aead;
/**
* struct aead_request - AEAD request
* @base: Common attributes for async crypto requests
* @assoclen: Length in bytes of associated data for authentication
* @cryptlen: Length of data to be encrypted or decrypted
* @iv: Initialisation vector
* @src: Source data
* @dst: Destination data
* @__ctx: Start of private context data
*/
struct aead_request {
struct crypto_async_request base;
unsigned int assoclen;
unsigned int cryptlen;
u8 *iv;
struct scatterlist *src;
struct scatterlist *dst;
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
/**
* struct aead_alg - AEAD cipher definition
* @maxauthsize: Set the maximum authentication tag size supported by the
* transformation. A transformation may support smaller tag sizes.
* As the authentication tag is a message digest to ensure the
* integrity of the encrypted data, a consumer typically wants the
* largest authentication tag possible as defined by this
* variable.
* @setauthsize: Set authentication size for the AEAD transformation. This
* function is used to specify the consumer requested size of the
* authentication tag to be either generated by the transformation
* during encryption or the size of the authentication tag to be
* supplied during the decryption operation. This function is also
* responsible for checking the authentication tag size for
* validity.
* @setkey: see struct skcipher_alg
* @encrypt: see struct skcipher_alg
* @decrypt: see struct skcipher_alg
* @ivsize: see struct skcipher_alg
* @chunksize: see struct skcipher_alg
* @init: Initialize the cryptographic transformation object. This function
* is used to initialize the cryptographic transformation object.
* This function is called only once at the instantiation time, right
* after the transformation context was allocated. In case the
* cryptographic hardware has some special requirements which need to
* be handled by software, this function shall check for the precise
* requirement of the transformation and put any software fallbacks
* in place.
* @exit: Deinitialize the cryptographic transformation object. This is a
* counterpart to @init, used to remove various changes set in
* @init.
* @base: Definition of a generic crypto cipher algorithm.
*
* All fields except @ivsize is mandatory and must be filled.
*/
struct aead_alg {
int (*setkey)(struct crypto_aead *tfm, const u8 *key,
unsigned int keylen);
int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
int (*encrypt)(struct aead_request *req);
int (*decrypt)(struct aead_request *req);
int (*init)(struct crypto_aead *tfm);
void (*exit)(struct crypto_aead *tfm);
unsigned int ivsize;
unsigned int maxauthsize;
unsigned int chunksize;
struct crypto_alg base;
};
struct crypto_aead {
unsigned int authsize;
unsigned int reqsize;
struct crypto_tfm base;
};
static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
{
return container_of(tfm, struct crypto_aead, base);
}
/**
* crypto_alloc_aead() - allocate AEAD cipher handle
* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
* AEAD cipher
* @type: specifies the type of the cipher
* @mask: specifies the mask for the cipher
*
* Allocate a cipher handle for an AEAD. The returned struct
* crypto_aead is the cipher handle that is required for any subsequent
* API invocation for that AEAD.
*
* Return: allocated cipher handle in case of success; IS_ERR() is true in case
* of an error, PTR_ERR() returns the error code.
*/
struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
{
return &tfm->base;
}
/**
* crypto_free_aead() - zeroize and free aead handle
* @tfm: cipher handle to be freed
*/
static inline void crypto_free_aead(struct crypto_aead *tfm)
{
crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
}
static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
{
return container_of(crypto_aead_tfm(tfm)->__crt_alg,
struct aead_alg, base);
}
static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
{
return alg->ivsize;
}
/**
* crypto_aead_ivsize() - obtain IV size
* @tfm: cipher handle
*
* The size of the IV for the aead referenced by the cipher handle is
* returned. This IV size may be zero if the cipher does not need an IV.
*
* Return: IV size in bytes
*/
static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
{
return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
}
/**
* crypto_aead_authsize() - obtain maximum authentication data size
* @tfm: cipher handle
*
* The maximum size of the authentication data for the AEAD cipher referenced
* by the AEAD cipher handle is returned. The authentication data size may be
* zero if the cipher implements a hard-coded maximum.
*
* The authentication data may also be known as "tag value".
*
* Return: authentication data size / tag size in bytes
*/
static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
{
return tfm->authsize;
}
/**
* crypto_aead_blocksize() - obtain block size of cipher
* @tfm: cipher handle
*
* The block size for the AEAD referenced with the cipher handle is returned.
* The caller may use that information to allocate appropriate memory for the
* data returned by the encryption or decryption operation
*
* Return: block size of cipher
*/
static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
{
return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
}
static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
{
return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
}
static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
{
return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
}
static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
{
crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
}
static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
{
crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
}
/**
* crypto_aead_setkey() - set key for cipher
* @tfm: cipher handle
* @key: buffer holding the key
* @keylen: length of the key in bytes
*
* The caller provided key is set for the AEAD referenced by the cipher
* handle.
*
* Note, the key length determines the cipher type. Many block ciphers implement
* different cipher modes depending on the key size, such as AES-128 vs AES-192
* vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
* is performed.
*
* Return: 0 if the setting of the key was successful; < 0 if an error occurred
*/
int crypto_aead_setkey(struct crypto_aead *tfm,
const u8 *key, unsigned int keylen);
/**
* crypto_aead_setauthsize() - set authentication data size
* @tfm: cipher handle
* @authsize: size of the authentication data / tag in bytes
*
* Set the authentication data size / tag size. AEAD requires an authentication
* tag (or MAC) in addition to the associated data.
*
* Return: 0 if the setting of the key was successful; < 0 if an error occurred
*/
int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
{
return __crypto_aead_cast(req->base.tfm);
}
/**
* crypto_aead_encrypt() - encrypt plaintext
* @req: reference to the aead_request handle that holds all information
* needed to perform the cipher operation
*
* Encrypt plaintext data using the aead_request handle. That data structure
* and how it is filled with data is discussed with the aead_request_*
* functions.
*
* IMPORTANT NOTE The encryption operation creates the authentication data /
* tag. That data is concatenated with the created ciphertext.
* The ciphertext memory size is therefore the given number of
* block cipher blocks + the size defined by the
* crypto_aead_setauthsize invocation. The caller must ensure
* that sufficient memory is available for the ciphertext and
* the authentication tag.
*
* Return: 0 if the cipher operation was successful; < 0 if an error occurred
*/
static inline int crypto_aead_encrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_alg *alg = aead->base.__crt_alg;
unsigned int cryptlen = req->cryptlen;
int ret;
crypto_stats_get(alg);
if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
ret = -ENOKEY;
else
ret = crypto_aead_alg(aead)->encrypt(req);
crypto_stats_aead_encrypt(cryptlen, alg, ret);
return ret;
}
/**
* crypto_aead_decrypt() - decrypt ciphertext
* @req: reference to the ablkcipher_request handle that holds all information
* needed to perform the cipher operation
*
* Decrypt ciphertext data using the aead_request handle. That data structure
* and how it is filled with data is discussed with the aead_request_*
* functions.
*
* IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
* authentication data / tag. That authentication data / tag
* must have the size defined by the crypto_aead_setauthsize
* invocation.
*
*
* Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
* cipher operation performs the authentication of the data during the
* decryption operation. Therefore, the function returns this error if
* the authentication of the ciphertext was unsuccessful (i.e. the
* integrity of the ciphertext or the associated data was violated);
* < 0 if an error occurred.
*/
static inline int crypto_aead_decrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_alg *alg = aead->base.__crt_alg;
unsigned int cryptlen = req->cryptlen;
int ret;
crypto_stats_get(alg);
if (crypto_aea
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