/*
* AEAD: Authenticated Encryption with Associated Data
*
- * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ * 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
#include <linux/slab.h>
/**
- * struct aead_givcrypt_request - AEAD request with IV generation
- * @seq: Sequence number for IV generation
- * @giv: Space for generated IV
- * @areq: The AEAD request itself
+ * 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 asynchronous block cipher operation
+ * applies here as well. Naturally all *ablkcipher* symbols must be exchanged
+ * the *aead* pendants discussed in the following. In addition, for the AEAD
+ * operation, the aead_request_set_assoc 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_givcrypt_request {
- u64 seq;
- u8 *giv;
+struct aead_request {
+ struct crypto_async_request base;
- struct aead_request areq;
+ unsigned int assoclen;
+ unsigned int cryptlen;
+
+ u8 *iv;
+
+ struct scatterlist *src;
+ struct scatterlist *dst;
+
+ void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
-static inline struct crypto_aead *aead_givcrypt_reqtfm(
- struct aead_givcrypt_request *req)
+/**
+ * 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 ablkcipher_alg
+ * @encrypt: see struct ablkcipher_alg
+ * @decrypt: see struct ablkcipher_alg
+ * @geniv: see struct ablkcipher_alg
+ * @ivsize: see struct ablkcipher_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.
+ *
+ * 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;
+
+ 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 crypto_aead_reqtfm(&req->areq);
+ return container_of(tfm, struct crypto_aead, base);
}
-static inline int crypto_aead_givencrypt(struct aead_givcrypt_request *req)
+/**
+ * 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)
{
- struct aead_tfm *crt = crypto_aead_crt(aead_givcrypt_reqtfm(req));
- return crt->givencrypt(req);
-};
+ return &tfm->base;
+}
+
+/**
+ * crypto_free_aead() - zeroize and free aead handle
+ * @tfm: cipher handle to be freed
+ */
+static inline void crypto_free_aead(struct crypto_aead *tfm)
+{
+ crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
+}
-static inline int crypto_aead_givdecrypt(struct aead_givcrypt_request *req)
+static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
{
- struct aead_tfm *crt = crypto_aead_crt(aead_givcrypt_reqtfm(req));
- return crt->givdecrypt(req);
-};
+ return container_of(crypto_aead_tfm(tfm)->__crt_alg,
+ struct aead_alg, base);
+}
-static inline void aead_givcrypt_set_tfm(struct aead_givcrypt_request *req,
- struct crypto_aead *tfm)
+static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
{
- req->areq.base.tfm = crypto_aead_tfm(tfm);
+ return alg->ivsize;
}
-static inline struct aead_givcrypt_request *aead_givcrypt_alloc(
- struct crypto_aead *tfm, gfp_t gfp)
+/**
+ * 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)
{
- struct aead_givcrypt_request *req;
+ return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
+}
- req = kmalloc(sizeof(struct aead_givcrypt_request) +
- crypto_aead_reqsize(tfm), gfp);
+/**
+ * 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;
+}
- if (likely(req))
- aead_givcrypt_set_tfm(req, tfm);
+/**
+ * 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));
+}
- return req;
+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)
+{
+ return crypto_aead_alg(crypto_aead_reqtfm(req))->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 (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;
}
-static inline void aead_givcrypt_free(struct aead_givcrypt_request *req)
+/**
+ * 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)
{
- kfree(req);
+ req->base.tfm = crypto_aead_tfm(tfm);
}
-static inline void aead_givcrypt_set_callback(
- struct aead_givcrypt_request *req, u32 flags,
- crypto_completion_t compl, void *data)
+/**
+ * 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; IS_ERR() is true in case
+ * of an error, PTR_ERR() returns the error code.
+ */
+static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
+ gfp_t gfp)
{
- aead_request_set_callback(&req->areq, flags, compl, data);
+ struct aead_request *req;
+
+ req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
+
+ if (likely(req))
+ aead_request_set_tfm(req, tfm);
+
+ return req;
}
-static inline void aead_givcrypt_set_crypt(struct aead_givcrypt_request *req,
- struct scatterlist *src,
- struct scatterlist *dst,
- unsigned int nbytes, void *iv)
+/**
+ * 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_crypt(&req->areq, src, dst, nbytes, iv);
+ kzfree(req);
}
-static inline void aead_givcrypt_set_assoc(struct aead_givcrypt_request *req,
- struct scatterlist *assoc,
- unsigned int assoclen)
+/**
+ * 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.
+ *
+ * For both src/dst the layout is associated data, plain/cipher text,
+ * authentication tag.
+ *
+ * The content of the AD in the destination buffer after processing
+ * will either be untouched, or it will contain a copy of the AD
+ * from the source buffer. In order to ensure that it always has
+ * a copy of the AD, the user must copy the AD over either before
+ * or after processing. Of course this is not relevant if the user
+ * is doing in-place processing where src == dst.
+ *
+ * IMPORTANT NOTE AEAD requires an authentication tag (MAC). For decryption,
+ * the caller must concatenate the ciphertext followed by the
+ * authentication tag and provide the entire data stream to the
+ * decryption operation (i.e. the data length used for the
+ * initialization of the scatterlist and the data length for the
+ * decryption operation is identical). For encryption, however,
+ * the authentication tag is created while encrypting the data.
+ * The destination buffer must hold sufficient space for the
+ * ciphertext and the authentication tag while the encryption
+ * invocation must only point to the plaintext data size. The
+ * following code snippet illustrates the memory usage
+ * buffer = kmalloc(ptbuflen + (enc ? authsize : 0));
+ * sg_init_one(&sg, buffer, ptbuflen + (enc ? authsize : 0));
+ * aead_request_set_crypt(req, &sg, &sg, ptbuflen, iv);
+ */
+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_assoc(&req->areq, assoc, assoclen);
+ req->src = src;
+ req->dst = dst;
+ req->cryptlen = cryptlen;
+ req->iv = iv;
}
-static inline void aead_givcrypt_set_giv(struct aead_givcrypt_request *req,
- u8 *giv, u64 seq)
+/**
+ * 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->giv = giv;
- req->seq = seq;
+ req->assoclen = assoclen;
}
#endif /* _CRYPTO_AEAD_H */
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