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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/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. 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:
  *
  * 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).
  *
  * 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 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
  *
  * 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 const char *crypto_aead_driver_name(struct crypto_aead *tfm)
 {
     return crypto_tfm_alg_driver_name(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;
 }
 
 static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
 {
     return alg->maxauthsize;
 }
 
 static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
 {
     return crypto_aead_alg_maxauthsize(crypto_aead_alg(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)
 {
     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
  */
 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)
 {
     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)
 {
     kfree_sensitive(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 || 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)
 {
     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 */

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