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diff --git a/include/crypto/aead.h b/include/crypto/aead.h new file mode 100644 index 000000000..c69c545ba --- /dev/null +++ b/include/crypto/aead.h @@ -0,0 +1,534 @@ +/* + * AEAD: Authenticated Encryption with Associated Data + * + * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + * + */ + +#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 + * @geniv: 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); + + const char *geniv; + + 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 + * + * If @tfm is a NULL or error pointer, this function does nothing. + */ +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); + + if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY) + return -ENOKEY; + + return crypto_aead_alg(aead)->encrypt(req); +} + +/** + * 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); + + if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY) + return -ENOKEY; + + if (req->cryptlen < crypto_aead_authsize(aead)) + return -EINVAL; + + return crypto_aead_alg(aead)->decrypt(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) +{ + return tfm->reqsize; +} + +/** + * 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) +{ + req->base.tfm = crypto_aead_tfm(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) +{ + struct aead_request *req; + + req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp); + + if (likely(req)) + aead_request_set_tfm(req, tfm); + + return req; +} + +/** + * 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) +{ + kzfree(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) +{ + req->base.complete = compl; + req->base.data = data; + req->base.flags = flags; +} + +/** + * 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 || cipherntext || 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) +{ + req->src = src; + req->dst = dst; + req->cryptlen = cryptlen; + req->iv = 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) +{ + req->assoclen = assoclen; +} + +#endif /* _CRYPTO_AEAD_H */ |