/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * AEAD: Authenticated Encryption with Associated Data * * Copyright (c) 2007-2015 Herbert Xu <[email protected]> */ #ifndef _CRYPTO_AEAD_H #define _CRYPTO_AEAD_H #include <linux/atomic.h> #include <linux/container_of.h> #include <linux/crypto.h> #include <linux/slab.h> #include <linux/types.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. 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: * * The source scatterlist must contain the concatenation of * associated data || plaintext or ciphertext. * * The destination scatterlist has the same layout, except that the plaintext * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size * during encryption (resp. decryption). The authentication tag is generated * during the encryption operation and appended to the ciphertext. During * decryption, the authentication tag is consumed along with the ciphertext and * used to verify the integrity of the plaintext and the associated data. * * In-place encryption/decryption is enabled by using the same scatterlist * pointer for both the source and destination. * * Even in the out-of-place case, space must be reserved in the destination for * the associated data, even though it won't be written to. This makes the * in-place and out-of-place cases more consistent. It is permissible for the * "destination" associated data to alias the "source" associated data. * * As with the other scatterlist crypto APIs, zero-length scatterlist elements * are not allowed in the used part of the scatterlist. Thus, if there is no * associated data, the first element must point to the plaintext/ciphertext. * * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309, * rfc4543, and rfc7539esp ciphers. For these ciphers, the final 'ivsize' bytes * of the associated data buffer must contain a second copy of the IV. This is * in addition to the copy passed to aead_request_set_crypt(). These two IV * copies must not differ; different implementations of the same algorithm may * behave differently in that case. Note that the algorithm might not actually * treat the IV as associated data; nevertheless the length passed to * aead_request_set_ad() must include it. */ struct crypto_aead; struct scatterlist; /** * 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 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 { … }; struct crypto_aead { … }; static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm) { … } /** * 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) { … } /** * crypto_free_aead() - zeroize and free aead handle * @tfm: cipher handle to be freed * * If @tfm is a NULL or error pointer, this function does nothing. */ static inline void crypto_free_aead(struct crypto_aead *tfm) { … } /** * crypto_has_aead() - Search for the availability of an aead. * @alg_name: is the cra_name / name or cra_driver_name / driver name of the * aead * @type: specifies the type of the aead * @mask: specifies the mask for the aead * * Return: true when the aead is known to the kernel crypto API; false * otherwise */ int crypto_has_aead(const char *alg_name, u32 type, u32 mask); static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm) { … } static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm) { … } static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg) { … } /** * 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) { … } /** * 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) { … } static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg) { … } static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead) { … } /** * 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) { … } static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm) { … } static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm) { … } static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags) { … } static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 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) { … } /** * 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 */ int crypto_aead_encrypt(struct aead_request *req); /** * crypto_aead_decrypt() - decrypt ciphertext * @req: reference to the aead_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. */ int crypto_aead_decrypt(struct aead_request *req); /** * DOC: Asynchronous AEAD Request Handle * * The aead_request data structure contains all pointers to data required for * the AEAD cipher operation. This includes the cipher handle (which can be * used by multiple aead_request instances), pointer to plaintext and * ciphertext, asynchronous callback function, etc. It acts as a handle to the * aead_request_* API calls in a similar way as AEAD handle to the * crypto_aead_* API calls. */ /** * crypto_aead_reqsize() - obtain size of the request data structure * @tfm: cipher handle * * Return: number of bytes */ static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm) { … } /** * aead_request_set_tfm() - update cipher handle reference in request * @req: request handle to be modified * @tfm: cipher handle that shall be added to the request handle * * Allow the caller to replace the existing aead handle in the request * data structure with a different one. */ static inline void aead_request_set_tfm(struct aead_request *req, struct crypto_aead *tfm) { … } /** * aead_request_alloc() - allocate request data structure * @tfm: cipher handle to be registered with the request * @gfp: memory allocation flag that is handed to kmalloc by the API call. * * Allocate the request data structure that must be used with the AEAD * encrypt and decrypt API calls. During the allocation, the provided aead * handle is registered in the request data structure. * * Return: allocated request handle in case of success, or NULL if out of memory */ static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm, gfp_t gfp) { … } /** * aead_request_free() - zeroize and free request data structure * @req: request data structure cipher handle to be freed */ static inline void aead_request_free(struct aead_request *req) { … } /** * aead_request_set_callback() - set asynchronous callback function * @req: request handle * @flags: specify zero or an ORing of the flags * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and * increase the wait queue beyond the initial maximum size; * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep * @compl: callback function pointer to be registered with the request handle * @data: The data pointer refers to memory that is not used by the kernel * crypto API, but provided to the callback function for it to use. Here, * the caller can provide a reference to memory the callback function can * operate on. As the callback function is invoked asynchronously to the * related functionality, it may need to access data structures of the * related functionality which can be referenced using this pointer. The * callback function can access the memory via the "data" field in the * crypto_async_request data structure provided to the callback function. * * Setting the callback function that is triggered once the cipher operation * completes * * The callback function is registered with the aead_request handle and * must comply with the following template:: * * void callback_function(struct crypto_async_request *req, int error) */ static inline void aead_request_set_callback(struct aead_request *req, u32 flags, crypto_completion_t compl, void *data) { … } /** * aead_request_set_crypt - set data buffers * @req: request handle * @src: source scatter / gather list * @dst: destination scatter / gather list * @cryptlen: number of bytes to process from @src * @iv: IV for the cipher operation which must comply with the IV size defined * by crypto_aead_ivsize() * * Setting the source data and destination data scatter / gather lists which * hold the associated data concatenated with the plaintext or ciphertext. See * below for the authentication tag. * * For encryption, the source is treated as the plaintext and the * destination is the ciphertext. For a decryption operation, the use is * reversed - the source is the ciphertext and the destination is the plaintext. * * The memory structure for cipher operation has the following structure: * * - AEAD encryption input: assoc data || plaintext * - AEAD encryption output: assoc data || ciphertext || auth tag * - AEAD decryption input: assoc data || ciphertext || auth tag * - AEAD decryption output: assoc data || plaintext * * Albeit the kernel requires the presence of the AAD buffer, however, * the kernel does not fill the AAD buffer in the output case. If the * caller wants to have that data buffer filled, the caller must either * use an in-place cipher operation (i.e. same memory location for * input/output memory location). */ static inline void aead_request_set_crypt(struct aead_request *req, struct scatterlist *src, struct scatterlist *dst, unsigned int cryptlen, u8 *iv) { … } /** * aead_request_set_ad - set associated data information * @req: request handle * @assoclen: number of bytes in associated data * * Setting the AD information. This function sets the length of * the associated data. */ static inline void aead_request_set_ad(struct aead_request *req, unsigned int assoclen) { … } #endif /* _CRYPTO_AEAD_H */
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