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528 lines
18 KiB
528 lines
18 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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/* |
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* AEAD: Authenticated Encryption with Associated Data |
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* |
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* Copyright (c) 2007-2015 Herbert Xu <[email protected]> |
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*/ |
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#ifndef _CRYPTO_AEAD_H |
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#define _CRYPTO_AEAD_H |
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#include <linux/crypto.h> |
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#include <linux/kernel.h> |
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#include <linux/slab.h> |
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/** |
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* DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API |
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* |
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* The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD |
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* (listed as type "aead" in /proc/crypto) |
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* |
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* The most prominent examples for this type of encryption is GCM and CCM. |
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* However, the kernel supports other types of AEAD ciphers which are defined |
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* with the following cipher string: |
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* |
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* authenc(keyed message digest, block cipher) |
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* |
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* For example: authenc(hmac(sha256), cbc(aes)) |
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* |
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* The example code provided for the symmetric key cipher operation |
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* applies here as well. Naturally all *skcipher* symbols must be exchanged |
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* the *aead* pendants discussed in the following. In addition, for the AEAD |
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* operation, the aead_request_set_ad function must be used to set the |
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* pointer to the associated data memory location before performing the |
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* encryption or decryption operation. In case of an encryption, the associated |
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* data memory is filled during the encryption operation. For decryption, the |
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* associated data memory must contain data that is used to verify the integrity |
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* of the decrypted data. Another deviation from the asynchronous block cipher |
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* operation is that the caller should explicitly check for -EBADMSG of the |
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* crypto_aead_decrypt. That error indicates an authentication error, i.e. |
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* a breach in the integrity of the message. In essence, that -EBADMSG error |
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* code is the key bonus an AEAD cipher has over "standard" block chaining |
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* modes. |
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* |
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* Memory Structure: |
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* |
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* The source scatterlist must contain the concatenation of |
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* associated data || plaintext or ciphertext. |
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* |
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* The destination scatterlist has the same layout, except that the plaintext |
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* (resp. ciphertext) will grow (resp. shrink) by the authentication tag size |
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* during encryption (resp. decryption). |
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* |
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* In-place encryption/decryption is enabled by using the same scatterlist |
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* pointer for both the source and destination. |
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* |
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* Even in the out-of-place case, space must be reserved in the destination for |
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* the associated data, even though it won't be written to. This makes the |
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* in-place and out-of-place cases more consistent. It is permissible for the |
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* "destination" associated data to alias the "source" associated data. |
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* |
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* As with the other scatterlist crypto APIs, zero-length scatterlist elements |
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* are not allowed in the used part of the scatterlist. Thus, if there is no |
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* associated data, the first element must point to the plaintext/ciphertext. |
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* |
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* To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309, |
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* rfc4543, and rfc7539esp ciphers. For these ciphers, the final 'ivsize' bytes |
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* of the associated data buffer must contain a second copy of the IV. This is |
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* in addition to the copy passed to aead_request_set_crypt(). These two IV |
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* copies must not differ; different implementations of the same algorithm may |
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* behave differently in that case. Note that the algorithm might not actually |
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* treat the IV as associated data; nevertheless the length passed to |
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* aead_request_set_ad() must include it. |
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*/ |
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struct crypto_aead; |
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/** |
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* struct aead_request - AEAD request |
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* @base: Common attributes for async crypto requests |
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* @assoclen: Length in bytes of associated data for authentication |
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* @cryptlen: Length of data to be encrypted or decrypted |
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* @iv: Initialisation vector |
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* @src: Source data |
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* @dst: Destination data |
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* @__ctx: Start of private context data |
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*/ |
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struct aead_request { |
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struct crypto_async_request base; |
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unsigned int assoclen; |
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unsigned int cryptlen; |
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u8 *iv; |
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struct scatterlist *src; |
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struct scatterlist *dst; |
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void *__ctx[] CRYPTO_MINALIGN_ATTR; |
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}; |
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/** |
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* struct aead_alg - AEAD cipher definition |
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* @maxauthsize: Set the maximum authentication tag size supported by the |
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* transformation. A transformation may support smaller tag sizes. |
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* As the authentication tag is a message digest to ensure the |
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* integrity of the encrypted data, a consumer typically wants the |
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* largest authentication tag possible as defined by this |
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* variable. |
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* @setauthsize: Set authentication size for the AEAD transformation. This |
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* function is used to specify the consumer requested size of the |
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* authentication tag to be either generated by the transformation |
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* during encryption or the size of the authentication tag to be |
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* supplied during the decryption operation. This function is also |
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* responsible for checking the authentication tag size for |
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* validity. |
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* @setkey: see struct skcipher_alg |
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* @encrypt: see struct skcipher_alg |
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* @decrypt: see struct skcipher_alg |
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* @ivsize: see struct skcipher_alg |
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* @chunksize: see struct skcipher_alg |
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* @init: Initialize the cryptographic transformation object. This function |
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* is used to initialize the cryptographic transformation object. |
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* This function is called only once at the instantiation time, right |
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* after the transformation context was allocated. In case the |
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* cryptographic hardware has some special requirements which need to |
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* be handled by software, this function shall check for the precise |
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* requirement of the transformation and put any software fallbacks |
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* in place. |
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* @exit: Deinitialize the cryptographic transformation object. This is a |
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* counterpart to @init, used to remove various changes set in |
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* @init. |
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* @base: Definition of a generic crypto cipher algorithm. |
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* |
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* All fields except @ivsize is mandatory and must be filled. |
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*/ |
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struct aead_alg { |
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int (*setkey)(struct crypto_aead *tfm, const u8 *key, |
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unsigned int keylen); |
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int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize); |
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int (*encrypt)(struct aead_request *req); |
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int (*decrypt)(struct aead_request *req); |
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int (*init)(struct crypto_aead *tfm); |
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void (*exit)(struct crypto_aead *tfm); |
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unsigned int ivsize; |
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unsigned int maxauthsize; |
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unsigned int chunksize; |
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struct crypto_alg base; |
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}; |
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struct crypto_aead { |
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unsigned int authsize; |
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unsigned int reqsize; |
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struct crypto_tfm base; |
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}; |
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static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm) |
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{ |
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return container_of(tfm, struct crypto_aead, base); |
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} |
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/** |
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* crypto_alloc_aead() - allocate AEAD cipher handle |
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* @alg_name: is the cra_name / name or cra_driver_name / driver name of the |
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* AEAD cipher |
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* @type: specifies the type of the cipher |
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* @mask: specifies the mask for the cipher |
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* |
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* Allocate a cipher handle for an AEAD. The returned struct |
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* crypto_aead is the cipher handle that is required for any subsequent |
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* API invocation for that AEAD. |
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* |
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* Return: allocated cipher handle in case of success; IS_ERR() is true in case |
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* of an error, PTR_ERR() returns the error code. |
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*/ |
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struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask); |
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static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm) |
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{ |
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return &tfm->base; |
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} |
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/** |
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* crypto_free_aead() - zeroize and free aead handle |
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* @tfm: cipher handle to be freed |
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* |
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* If @tfm is a NULL or error pointer, this function does nothing. |
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*/ |
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static inline void crypto_free_aead(struct crypto_aead *tfm) |
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{ |
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crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm)); |
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} |
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static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm) |
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{ |
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return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm)); |
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} |
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static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm) |
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{ |
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return container_of(crypto_aead_tfm(tfm)->__crt_alg, |
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struct aead_alg, base); |
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} |
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static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg) |
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{ |
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return alg->ivsize; |
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} |
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/** |
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* crypto_aead_ivsize() - obtain IV size |
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* @tfm: cipher handle |
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* |
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* The size of the IV for the aead referenced by the cipher handle is |
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* returned. This IV size may be zero if the cipher does not need an IV. |
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* |
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* Return: IV size in bytes |
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*/ |
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static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm) |
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{ |
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return crypto_aead_alg_ivsize(crypto_aead_alg(tfm)); |
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} |
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/** |
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* crypto_aead_authsize() - obtain maximum authentication data size |
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* @tfm: cipher handle |
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* |
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* The maximum size of the authentication data for the AEAD cipher referenced |
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* by the AEAD cipher handle is returned. The authentication data size may be |
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* zero if the cipher implements a hard-coded maximum. |
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* |
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* The authentication data may also be known as "tag value". |
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* |
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* Return: authentication data size / tag size in bytes |
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*/ |
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static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm) |
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{ |
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return tfm->authsize; |
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} |
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static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg) |
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{ |
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return alg->maxauthsize; |
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} |
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static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead) |
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{ |
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return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead)); |
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} |
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/** |
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* crypto_aead_blocksize() - obtain block size of cipher |
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* @tfm: cipher handle |
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* |
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* The block size for the AEAD referenced with the cipher handle is returned. |
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* The caller may use that information to allocate appropriate memory for the |
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* data returned by the encryption or decryption operation |
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* |
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* Return: block size of cipher |
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*/ |
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static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm) |
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{ |
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return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm)); |
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} |
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static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm) |
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{ |
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return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm)); |
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} |
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static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm) |
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{ |
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return crypto_tfm_get_flags(crypto_aead_tfm(tfm)); |
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} |
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static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags) |
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{ |
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crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags); |
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} |
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static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags) |
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{ |
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crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags); |
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} |
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/** |
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* crypto_aead_setkey() - set key for cipher |
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* @tfm: cipher handle |
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* @key: buffer holding the key |
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* @keylen: length of the key in bytes |
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* |
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* The caller provided key is set for the AEAD referenced by the cipher |
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* handle. |
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* |
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* Note, the key length determines the cipher type. Many block ciphers implement |
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* different cipher modes depending on the key size, such as AES-128 vs AES-192 |
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* vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128 |
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* is performed. |
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* |
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* Return: 0 if the setting of the key was successful; < 0 if an error occurred |
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*/ |
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int crypto_aead_setkey(struct crypto_aead *tfm, |
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const u8 *key, unsigned int keylen); |
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/** |
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* crypto_aead_setauthsize() - set authentication data size |
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* @tfm: cipher handle |
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* @authsize: size of the authentication data / tag in bytes |
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* |
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* Set the authentication data size / tag size. AEAD requires an authentication |
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* tag (or MAC) in addition to the associated data. |
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* |
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* Return: 0 if the setting of the key was successful; < 0 if an error occurred |
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*/ |
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int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize); |
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static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req) |
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{ |
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return __crypto_aead_cast(req->base.tfm); |
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} |
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/** |
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* crypto_aead_encrypt() - encrypt plaintext |
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* @req: reference to the aead_request handle that holds all information |
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* needed to perform the cipher operation |
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* |
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* Encrypt plaintext data using the aead_request handle. That data structure |
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* and how it is filled with data is discussed with the aead_request_* |
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* functions. |
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* |
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* IMPORTANT NOTE The encryption operation creates the authentication data / |
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* tag. That data is concatenated with the created ciphertext. |
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* The ciphertext memory size is therefore the given number of |
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* block cipher blocks + the size defined by the |
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* crypto_aead_setauthsize invocation. The caller must ensure |
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* that sufficient memory is available for the ciphertext and |
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* the authentication tag. |
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* |
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* Return: 0 if the cipher operation was successful; < 0 if an error occurred |
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*/ |
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int crypto_aead_encrypt(struct aead_request *req); |
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/** |
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* crypto_aead_decrypt() - decrypt ciphertext |
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* @req: reference to the aead_request handle that holds all information |
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* needed to perform the cipher operation |
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* |
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* Decrypt ciphertext data using the aead_request handle. That data structure |
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* and how it is filled with data is discussed with the aead_request_* |
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* functions. |
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* |
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* IMPORTANT NOTE The caller must concatenate the ciphertext followed by the |
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* authentication data / tag. That authentication data / tag |
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* must have the size defined by the crypto_aead_setauthsize |
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* invocation. |
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* |
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* |
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* Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD |
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* cipher operation performs the authentication of the data during the |
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* decryption operation. Therefore, the function returns this error if |
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* the authentication of the ciphertext was unsuccessful (i.e. the |
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* integrity of the ciphertext or the associated data was violated); |
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* < 0 if an error occurred. |
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*/ |
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int crypto_aead_decrypt(struct aead_request *req); |
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/** |
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* DOC: Asynchronous AEAD Request Handle |
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* |
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* The aead_request data structure contains all pointers to data required for |
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* the AEAD cipher operation. This includes the cipher handle (which can be |
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* used by multiple aead_request instances), pointer to plaintext and |
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* ciphertext, asynchronous callback function, etc. It acts as a handle to the |
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* aead_request_* API calls in a similar way as AEAD handle to the |
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* crypto_aead_* API calls. |
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*/ |
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/** |
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* crypto_aead_reqsize() - obtain size of the request data structure |
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* @tfm: cipher handle |
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* |
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* Return: number of bytes |
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*/ |
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static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm) |
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{ |
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return tfm->reqsize; |
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} |
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/** |
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* aead_request_set_tfm() - update cipher handle reference in request |
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* @req: request handle to be modified |
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* @tfm: cipher handle that shall be added to the request handle |
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* |
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* Allow the caller to replace the existing aead handle in the request |
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* data structure with a different one. |
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*/ |
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static inline void aead_request_set_tfm(struct aead_request *req, |
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struct crypto_aead *tfm) |
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{ |
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req->base.tfm = crypto_aead_tfm(tfm); |
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} |
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/** |
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* aead_request_alloc() - allocate request data structure |
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* @tfm: cipher handle to be registered with the request |
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* @gfp: memory allocation flag that is handed to kmalloc by the API call. |
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* |
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* Allocate the request data structure that must be used with the AEAD |
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* encrypt and decrypt API calls. During the allocation, the provided aead |
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* handle is registered in the request data structure. |
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* |
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* Return: allocated request handle in case of success, or NULL if out of memory |
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*/ |
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static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm, |
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gfp_t gfp) |
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{ |
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struct aead_request *req; |
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req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp); |
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if (likely(req)) |
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aead_request_set_tfm(req, tfm); |
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return req; |
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} |
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/** |
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* aead_request_free() - zeroize and free request data structure |
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* @req: request data structure cipher handle to be freed |
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*/ |
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static inline void aead_request_free(struct aead_request *req) |
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{ |
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kfree_sensitive(req); |
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} |
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/** |
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* aead_request_set_callback() - set asynchronous callback function |
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* @req: request handle |
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* @flags: specify zero or an ORing of the flags |
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* CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and |
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* increase the wait queue beyond the initial maximum size; |
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* CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep |
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* @compl: callback function pointer to be registered with the request handle |
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* @data: The data pointer refers to memory that is not used by the kernel |
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* crypto API, but provided to the callback function for it to use. Here, |
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* the caller can provide a reference to memory the callback function can |
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* operate on. As the callback function is invoked asynchronously to the |
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* related functionality, it may need to access data structures of the |
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* related functionality which can be referenced using this pointer. The |
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* callback function can access the memory via the "data" field in the |
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* crypto_async_request data structure provided to the callback function. |
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* |
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* Setting the callback function that is triggered once the cipher operation |
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* completes |
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* |
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* The callback function is registered with the aead_request handle and |
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* must comply with the following template:: |
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* |
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* void callback_function(struct crypto_async_request *req, int error) |
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*/ |
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static inline void aead_request_set_callback(struct aead_request *req, |
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u32 flags, |
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crypto_completion_t compl, |
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void *data) |
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{ |
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req->base.complete = compl; |
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req->base.data = data; |
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req->base.flags = flags; |
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} |
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/** |
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* aead_request_set_crypt - set data buffers |
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* @req: request handle |
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* @src: source scatter / gather list |
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* @dst: destination scatter / gather list |
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* @cryptlen: number of bytes to process from @src |
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* @iv: IV for the cipher operation which must comply with the IV size defined |
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* by crypto_aead_ivsize() |
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* |
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* Setting the source data and destination data scatter / gather lists which |
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* hold the associated data concatenated with the plaintext or ciphertext. See |
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* below for the authentication tag. |
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* |
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* For encryption, the source is treated as the plaintext and the |
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* destination is the ciphertext. For a decryption operation, the use is |
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* reversed - the source is the ciphertext and the destination is the plaintext. |
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* |
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* The memory structure for cipher operation has the following structure: |
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* |
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* - AEAD encryption input: assoc data || plaintext |
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* - AEAD encryption output: assoc data || cipherntext || auth tag |
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* - AEAD decryption input: assoc data || ciphertext || auth tag |
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* - AEAD decryption output: assoc data || plaintext |
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* |
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* Albeit the kernel requires the presence of the AAD buffer, however, |
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* the kernel does not fill the AAD buffer in the output case. If the |
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* caller wants to have that data buffer filled, the caller must either |
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* use an in-place cipher operation (i.e. same memory location for |
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* input/output memory location). |
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*/ |
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static inline void aead_request_set_crypt(struct aead_request *req, |
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struct scatterlist *src, |
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struct scatterlist *dst, |
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unsigned int cryptlen, u8 *iv) |
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{ |
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req->src = src; |
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req->dst = dst; |
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req->cryptlen = cryptlen; |
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req->iv = iv; |
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} |
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/** |
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* aead_request_set_ad - set associated data information |
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* @req: request handle |
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* @assoclen: number of bytes in associated data |
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* |
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* Setting the AD information. This function sets the length of |
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* the associated data. |
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*/ |
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static inline void aead_request_set_ad(struct aead_request *req, |
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unsigned int assoclen) |
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{ |
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req->assoclen = assoclen; |
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} |
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#endif /* _CRYPTO_AEAD_H */
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