crypto: skcipher - Add low-level skcipher interface
This patch allows skcipher algorithms and instances to be created
and registered with the crypto API. They are accessible through
the top-level skcipher interface, along with ablkcipher/blkcipher
algorithms and instances.
This patch also introduces a new parameter called chunk size
which is meant for ciphers such as CTR and CTS which ostensibly
can handle arbitrary lengths, but still behave like block ciphers
in that you can only process a partial block at the very end.
For these ciphers the block size will continue to be set to 1
as it is now while the chunk size will be set to the underlying
block size.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h
index 0f987f5..a381f57 100644
--- a/include/crypto/skcipher.h
+++ b/include/crypto/skcipher.h
@@ -65,6 +65,75 @@
struct crypto_tfm base;
};
+/**
+ * struct skcipher_alg - symmetric key cipher definition
+ * @min_keysize: Minimum key size supported by the transformation. This is the
+ * smallest key length supported by this transformation algorithm.
+ * This must be set to one of the pre-defined values as this is
+ * not hardware specific. Possible values for this field can be
+ * found via git grep "_MIN_KEY_SIZE" include/crypto/
+ * @max_keysize: Maximum key size supported by the transformation. This is the
+ * largest key length supported by this transformation algorithm.
+ * This must be set to one of the pre-defined values as this is
+ * not hardware specific. Possible values for this field can be
+ * found via git grep "_MAX_KEY_SIZE" include/crypto/
+ * @setkey: Set key for the transformation. This function is used to either
+ * program a supplied key into the hardware or store the key in the
+ * transformation context for programming it later. Note that this
+ * function does modify the transformation context. This function can
+ * be called multiple times during the existence of the transformation
+ * object, so one must make sure the key is properly reprogrammed into
+ * the hardware. This function is also responsible for checking the key
+ * length for validity. In case a software fallback was put in place in
+ * the @cra_init call, this function might need to use the fallback if
+ * the algorithm doesn't support all of the key sizes.
+ * @encrypt: Encrypt a scatterlist of blocks. This function is used to encrypt
+ * the supplied scatterlist containing the blocks of data. The crypto
+ * API consumer is responsible for aligning the entries of the
+ * scatterlist properly and making sure the chunks are correctly
+ * sized. In case a software fallback was put in place in the
+ * @cra_init call, this function might need to use the fallback if
+ * the algorithm doesn't support all of the key sizes. In case the
+ * key was stored in transformation context, the key might need to be
+ * re-programmed into the hardware in this function. This function
+ * shall not modify the transformation context, as this function may
+ * be called in parallel with the same transformation object.
+ * @decrypt: Decrypt a single block. This is a reverse counterpart to @encrypt
+ * and the conditions are exactly the same.
+ * @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.
+ * @ivsize: IV size applicable for transformation. The consumer must provide an
+ * IV of exactly that size to perform the encrypt or decrypt operation.
+ * @chunksize: Equal to the block size except for stream ciphers such as
+ * CTR where it is set to the underlying block size.
+ *
+ * All fields except @ivsize are mandatory and must be filled.
+ */
+struct skcipher_alg {
+ int (*setkey)(struct crypto_skcipher *tfm, const u8 *key,
+ unsigned int keylen);
+ int (*encrypt)(struct skcipher_request *req);
+ int (*decrypt)(struct skcipher_request *req);
+ int (*init)(struct crypto_skcipher *tfm);
+ void (*exit)(struct crypto_skcipher *tfm);
+
+ unsigned int min_keysize;
+ unsigned int max_keysize;
+ unsigned int ivsize;
+ unsigned int chunksize;
+
+ struct crypto_alg base;
+};
+
#define SKCIPHER_REQUEST_ON_STACK(name, tfm) \
char __##name##_desc[sizeof(struct skcipher_request) + \
crypto_skcipher_reqsize(tfm)] CRYPTO_MINALIGN_ATTR; \
@@ -231,12 +300,43 @@
crypto_skcipher_mask(mask));
}
+/**
+ * crypto_has_skcipher2() - Search for the availability of an skcipher.
+ * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
+ * skcipher
+ * @type: specifies the type of the skcipher
+ * @mask: specifies the mask for the skcipher
+ *
+ * Return: true when the skcipher is known to the kernel crypto API; false
+ * otherwise
+ */
+int crypto_has_skcipher2(const char *alg_name, u32 type, u32 mask);
+
static inline const char *crypto_skcipher_driver_name(
struct crypto_skcipher *tfm)
{
return crypto_tfm_alg_driver_name(crypto_skcipher_tfm(tfm));
}
+static inline struct skcipher_alg *crypto_skcipher_alg(
+ struct crypto_skcipher *tfm)
+{
+ return container_of(crypto_skcipher_tfm(tfm)->__crt_alg,
+ struct skcipher_alg, base);
+}
+
+static inline unsigned int crypto_skcipher_alg_ivsize(struct skcipher_alg *alg)
+{
+ if ((alg->base.cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+ CRYPTO_ALG_TYPE_BLKCIPHER)
+ return alg->base.cra_blkcipher.ivsize;
+
+ if (alg->base.cra_ablkcipher.encrypt)
+ return alg->base.cra_ablkcipher.ivsize;
+
+ return alg->ivsize;
+}
+
/**
* crypto_skcipher_ivsize() - obtain IV size
* @tfm: cipher handle
@@ -251,6 +351,36 @@
return tfm->ivsize;
}
+static inline unsigned int crypto_skcipher_alg_chunksize(
+ struct skcipher_alg *alg)
+{
+ if ((alg->base.cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+ CRYPTO_ALG_TYPE_BLKCIPHER)
+ return alg->base.cra_blocksize;
+
+ if (alg->base.cra_ablkcipher.encrypt)
+ return alg->base.cra_blocksize;
+
+ return alg->chunksize;
+}
+
+/**
+ * crypto_skcipher_chunksize() - obtain chunk size
+ * @tfm: cipher handle
+ *
+ * The block size is set to one for ciphers such as CTR. However,
+ * you still need to provide incremental updates in multiples of
+ * the underlying block size as the IV does not have sub-block
+ * granularity. This is known in this API as the chunk size.
+ *
+ * Return: chunk size in bytes
+ */
+static inline unsigned int crypto_skcipher_chunksize(
+ struct crypto_skcipher *tfm)
+{
+ return crypto_skcipher_alg_chunksize(crypto_skcipher_alg(tfm));
+}
+
/**
* crypto_skcipher_blocksize() - obtain block size of cipher
* @tfm: cipher handle
