4 files changed, 651 insertions, 1 deletions

diff --git a/crypto/Makefile b/crypto/Makefile
index f6229aef7595..e2c59819b236 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_CRYPTO_AEAD2) += aead.o
 
 crypto_blkcipher-y := ablkcipher.o
 crypto_blkcipher-y += blkcipher.o
+crypto_blkcipher-y += skcipher.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += crypto_blkcipher.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += chainiv.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += eseqiv.o
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
new file mode 100644
index 000000000000..dd5fc1bf6447
--- /dev/null
+++ b/crypto/skcipher.c
@@ -0,0 +1,245 @@
+/*
+ * Symmetric key cipher operations.
+ *
+ * Generic encrypt/decrypt wrapper for ciphers, handles operations across
+ * multiple page boundaries by using temporary blocks.  In user context,
+ * the kernel is given a chance to schedule us once per page.
+ *
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <crypto/internal/skcipher.h>
+#include <linux/bug.h>
+#include <linux/module.h>
+
+#include "internal.h"
+
+static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
+{
+        if (alg->cra_type == &crypto_blkcipher_type)
+                return sizeof(struct crypto_blkcipher *);
+
+        BUG_ON(alg->cra_type != &crypto_ablkcipher_type &&
+               alg->cra_type != &crypto_givcipher_type);
+
+        return sizeof(struct crypto_ablkcipher *);
+}
+
+static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
+                                     const u8 *key, unsigned int keylen)
+{
+        struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
+        struct crypto_blkcipher *blkcipher = *ctx;
+        int err;
+
+        crypto_blkcipher_clear_flags(blkcipher, ~0);
+        crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
+                                              CRYPTO_TFM_REQ_MASK);
+        err = crypto_blkcipher_setkey(blkcipher, key, keylen);
+        crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
+                                       CRYPTO_TFM_RES_MASK);
+
+        return err;
+}
+
+static int skcipher_crypt_blkcipher(struct skcipher_request *req,
+                                    int (*crypt)(struct blkcipher_desc *,
+                                                 struct scatterlist *,
+                                                 struct scatterlist *,
+                                                 unsigned int))
+{
+        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+        struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
+        struct blkcipher_desc desc = {
+                .tfm = *ctx,
+                .info = req->iv,
+                .flags = req->base.flags,
+        };
+
+
+        return crypt(&desc, req->dst, req->src, req->cryptlen);
+}
+
+static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
+{
+        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
+
+        return skcipher_crypt_blkcipher(req, alg->encrypt);
+}
+
+static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
+{
+        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
+
+        return skcipher_crypt_blkcipher(req, alg->decrypt);
+}
+
+static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
+{
+        struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
+
+        crypto_free_blkcipher(*ctx);
+}
+
+int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
+{
+        struct crypto_alg *calg = tfm->__crt_alg;
+        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
+        struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
+        struct crypto_blkcipher *blkcipher;
+        struct crypto_tfm *btfm;
+
+        if (!crypto_mod_get(calg))
+                return -EAGAIN;
+
+        btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
+                                        CRYPTO_ALG_TYPE_MASK);
+        if (IS_ERR(btfm)) {
+                crypto_mod_put(calg);
+                return PTR_ERR(btfm);
+        }
+
+        blkcipher = __crypto_blkcipher_cast(btfm);
+        *ctx = blkcipher;
+        tfm->exit = crypto_exit_skcipher_ops_blkcipher;
+
+        skcipher->setkey = skcipher_setkey_blkcipher;
+        skcipher->encrypt = skcipher_encrypt_blkcipher;
+        skcipher->decrypt = skcipher_decrypt_blkcipher;
+
+        skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
+
+        return 0;
+}
+
+static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
+                                      const u8 *key, unsigned int keylen)
+{
+        struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
+        struct crypto_ablkcipher *ablkcipher = *ctx;
+        int err;
+
+        crypto_ablkcipher_clear_flags(ablkcipher, ~0);
+        crypto_ablkcipher_set_flags(ablkcipher,
+                                    crypto_skcipher_get_flags(tfm) &
+                                    CRYPTO_TFM_REQ_MASK);
+        err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
+        crypto_skcipher_set_flags(tfm,
+                                  crypto_ablkcipher_get_flags(ablkcipher) &
+                                  CRYPTO_TFM_RES_MASK);
+
+        return err;
+}
+
+static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
+                                     int (*crypt)(struct ablkcipher_request *))
+{
+        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+        struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
+        struct ablkcipher_request *subreq = skcipher_request_ctx(req);
+
+        ablkcipher_request_set_tfm(subreq, *ctx);
+        ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
+                                        req->base.complete, req->base.data);
+        ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
+                                     req->iv);
+
+        return crypt(subreq);
+}
+
+static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
+{
+        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+        struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
+
+        return skcipher_crypt_ablkcipher(req, alg->encrypt);
+}
+
+static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
+{
+        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+        struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
+
+        return skcipher_crypt_ablkcipher(req, alg->decrypt);
+}
+
+static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
+{
+        struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
+
+        crypto_free_ablkcipher(*ctx);
+}
+
+int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
+{
+        struct crypto_alg *calg = tfm->__crt_alg;
+        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
+        struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
+        struct crypto_ablkcipher *ablkcipher;
+        struct crypto_tfm *abtfm;
+
+        if (!crypto_mod_get(calg))
+                return -EAGAIN;
+
+        abtfm = __crypto_alloc_tfm(calg, 0, 0);
+        if (IS_ERR(abtfm)) {
+                crypto_mod_put(calg);
+                return PTR_ERR(abtfm);
+        }
+
+        ablkcipher = __crypto_ablkcipher_cast(abtfm);
+        *ctx = ablkcipher;
+        tfm->exit = crypto_exit_skcipher_ops_ablkcipher;
+
+        skcipher->setkey = skcipher_setkey_ablkcipher;
+        skcipher->encrypt = skcipher_encrypt_ablkcipher;
+        skcipher->decrypt = skcipher_decrypt_ablkcipher;
+
+        skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+        skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
+                            sizeof(struct ablkcipher_request);
+
+        return 0;
+}
+
+static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
+{
+        if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
+                return crypto_init_skcipher_ops_blkcipher(tfm);
+
+        BUG_ON(tfm->__crt_alg->cra_type != &crypto_ablkcipher_type &&
+               tfm->__crt_alg->cra_type != &crypto_givcipher_type);
+
+        return crypto_init_skcipher_ops_ablkcipher(tfm);
+}
+
+static const struct crypto_type crypto_skcipher_type2 = {
+        .extsize = crypto_skcipher_extsize,
+        .init_tfm = crypto_skcipher_init_tfm,
+        .maskclear = ~CRYPTO_ALG_TYPE_MASK,
+        .maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
+        .type = CRYPTO_ALG_TYPE_BLKCIPHER,
+        .tfmsize = offsetof(struct crypto_skcipher, base),
+};
+
+struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
+                                              u32 type, u32 mask)
+{
+        return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Symmetric key cipher type");
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index b3a46c515d1b..2cf7a61ece59 100644
--- a/include/crypto/internal/skcipher.h
+++ b/include/crypto/internal/skcipher.h
@@ -107,5 +107,20 @@ static inline u32 ablkcipher_request_flags(struct ablkcipher_request *req)
         return req->base.flags;
 }
 
+static inline void *crypto_skcipher_ctx(struct crypto_skcipher *tfm)
+{
+        return crypto_tfm_ctx(&tfm->base);
+}
+
+static inline void *skcipher_request_ctx(struct skcipher_request *req)
+{
+        return req->__ctx;
+}
+
+static inline u32 skcipher_request_flags(struct skcipher_request *req)
+{
+        return req->base.flags;
+}
+
 #endif  /* _CRYPTO_INTERNAL_SKCIPHER_H */
 
diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h
index 07d245f073d1..d8dd41fb034f 100644
--- a/include/crypto/skcipher.h
+++ b/include/crypto/skcipher.h
@@ -1,7 +1,7 @@
 /*
  * Symmetric key ciphers.
  * 
- * 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
@@ -18,6 +18,28 @@
 #include <linux/slab.h>
 
 /**
+ *      struct skcipher_request - Symmetric key cipher request
+ *      @cryptlen: Number of bytes to encrypt or decrypt
+ *      @iv: Initialisation Vector
+ *      @src: Source SG list
+ *      @dst: Destination SG list
+ *      @base: Underlying async request request
+ *      @__ctx: Start of private context data
+ */
+struct skcipher_request {
+        unsigned int cryptlen;
+
+        u8 *iv;
+
+        struct scatterlist *src;
+        struct scatterlist *dst;
+
+        struct crypto_async_request base;
+
+        void *__ctx[] CRYPTO_MINALIGN_ATTR;
+};
+
+/**
  *      struct skcipher_givcrypt_request - Crypto request with IV generation
  *      @seq: Sequence number for IV generation
  *      @giv: Space for generated IV
@@ -30,6 +52,23 @@ struct skcipher_givcrypt_request {
         struct ablkcipher_request creq;
 };
 
+struct crypto_skcipher {
+        int (*setkey)(struct crypto_skcipher *tfm, const u8 *key,
+                      unsigned int keylen);
+        int (*encrypt)(struct skcipher_request *req);
+        int (*decrypt)(struct skcipher_request *req);
+
+        unsigned int ivsize;
+        unsigned int reqsize;
+
+        struct crypto_tfm base;
+};
+
+#define SKCIPHER_REQUEST_ON_STACK(name, tfm) \
+        char __##name##_desc[sizeof(struct skcipher_request) + \
+                crypto_skcipher_reqsize(tfm)] CRYPTO_MINALIGN_ATTR; \
+        struct skcipher_request *name = (void *)__##name##_desc
+
 static inline struct crypto_ablkcipher *skcipher_givcrypt_reqtfm(
         struct skcipher_givcrypt_request *req)
 {
@@ -106,5 +145,355 @@ static inline void skcipher_givcrypt_set_giv(
         req->seq = seq;
 }
 
+/**
+ * DOC: Symmetric Key Cipher API
+ *
+ * Symmetric key cipher API is used with the ciphers of type
+ * CRYPTO_ALG_TYPE_SKCIPHER (listed as type "skcipher" in /proc/crypto).
+ *
+ * Asynchronous cipher operations imply that the function invocation for a
+ * cipher request returns immediately before the completion of the operation.
+ * The cipher request is scheduled as a separate kernel thread and therefore
+ * load-balanced on the different CPUs via the process scheduler. To allow
+ * the kernel crypto API to inform the caller about the completion of a cipher
+ * request, the caller must provide a callback function. That function is
+ * invoked with the cipher handle when the request completes.
+ *
+ * To support the asynchronous operation, additional information than just the
+ * cipher handle must be supplied to the kernel crypto API. That additional
+ * information is given by filling in the skcipher_request data structure.
+ *
+ * For the symmetric key cipher API, the state is maintained with the tfm
+ * cipher handle. A single tfm can be used across multiple calls and in
+ * parallel. For asynchronous block cipher calls, context data supplied and
+ * only used by the caller can be referenced the request data structure in
+ * addition to the IV used for the cipher request. The maintenance of such
+ * state information would be important for a crypto driver implementer to
+ * have, because when calling the callback function upon completion of the
+ * cipher operation, that callback function may need some information about
+ * which operation just finished if it invoked multiple in parallel. This
+ * state information is unused by the kernel crypto API.
+ */
+
+static inline struct crypto_skcipher *__crypto_skcipher_cast(
+        struct crypto_tfm *tfm)
+{
+        return container_of(tfm, struct crypto_skcipher, base);
+}
+
+/**
+ * crypto_alloc_skcipher() - allocate symmetric key cipher handle
+ * @alg_name: is the cra_name / name or cra_driver_name / driver name of the
+ *            skcipher cipher
+ * @type: specifies the type of the cipher
+ * @mask: specifies the mask for the cipher
+ *
+ * Allocate a cipher handle for an skcipher. The returned struct
+ * crypto_skcipher is the cipher handle that is required for any subsequent
+ * API invocation for that skcipher.
+ *
+ * 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_skcipher *crypto_alloc_skcipher(const char *alg_name,
+                                              u32 type, u32 mask);
+
+static inline struct crypto_tfm *crypto_skcipher_tfm(
+        struct crypto_skcipher *tfm)
+{
+        return &tfm->base;
+}
+
+/**
+ * crypto_free_skcipher() - zeroize and free cipher handle
+ * @tfm: cipher handle to be freed
+ */
+static inline void crypto_free_skcipher(struct crypto_skcipher *tfm)
+{
+        crypto_destroy_tfm(tfm, crypto_skcipher_tfm(tfm));
+}
+
+/**
+ * crypto_has_skcipher() - 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 cipher
+ * @mask: specifies the mask for the cipher
+ *
+ * Return: true when the skcipher is known to the kernel crypto API; false
+ *         otherwise
+ */
+static inline int crypto_has_skcipher(const char *alg_name, u32 type,
+                                        u32 mask)
+{
+        return crypto_has_alg(alg_name, crypto_skcipher_type(type),
+                              crypto_skcipher_mask(mask));
+}
+
+/**
+ * crypto_skcipher_ivsize() - obtain IV size
+ * @tfm: cipher handle
+ *
+ * The size of the IV for the skcipher 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_skcipher_ivsize(struct crypto_skcipher *tfm)
+{
+        return tfm->ivsize;
+}
+
+/**
+ * crypto_skcipher_blocksize() - obtain block size of cipher
+ * @tfm: cipher handle
+ *
+ * The block size for the skcipher 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_skcipher_blocksize(
+        struct crypto_skcipher *tfm)
+{
+        return crypto_tfm_alg_blocksize(crypto_skcipher_tfm(tfm));
+}
+
+static inline unsigned int crypto_skcipher_alignmask(
+        struct crypto_skcipher *tfm)
+{
+        return crypto_tfm_alg_alignmask(crypto_skcipher_tfm(tfm));
+}
+
+static inline u32 crypto_skcipher_get_flags(struct crypto_skcipher *tfm)
+{
+        return crypto_tfm_get_flags(crypto_skcipher_tfm(tfm));
+}
+
+static inline void crypto_skcipher_set_flags(struct crypto_skcipher *tfm,
+                                               u32 flags)
+{
+        crypto_tfm_set_flags(crypto_skcipher_tfm(tfm), flags);
+}
+
+static inline void crypto_skcipher_clear_flags(struct crypto_skcipher *tfm,
+                                                 u32 flags)
+{
+        crypto_tfm_clear_flags(crypto_skcipher_tfm(tfm), flags);
+}
+
+/**
+ * crypto_skcipher_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 skcipher 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
+ */
+static inline int crypto_skcipher_setkey(struct crypto_skcipher *tfm,
+                                         const u8 *key, unsigned int keylen)
+{
+        return tfm->setkey(tfm, key, keylen);
+}
+
+/**
+ * crypto_skcipher_reqtfm() - obtain cipher handle from request
+ * @req: skcipher_request out of which the cipher handle is to be obtained
+ *
+ * Return the crypto_skcipher handle when furnishing an skcipher_request
+ * data structure.
+ *
+ * Return: crypto_skcipher handle
+ */
+static inline struct crypto_skcipher *crypto_skcipher_reqtfm(
+        struct skcipher_request *req)
+{
+        return __crypto_skcipher_cast(req->base.tfm);
+}
+
+/**
+ * crypto_skcipher_encrypt() - encrypt plaintext
+ * @req: reference to the skcipher_request handle that holds all information
+ *       needed to perform the cipher operation
+ *
+ * Encrypt plaintext data using the skcipher_request handle. That data
+ * structure and how it is filled with data is discussed with the
+ * skcipher_request_* functions.
+ *
+ * Return: 0 if the cipher operation was successful; < 0 if an error occurred
+ */
+static inline int crypto_skcipher_encrypt(struct skcipher_request *req)
+{
+        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+
+        return tfm->encrypt(req);
+}
+
+/**
+ * crypto_skcipher_decrypt() - decrypt ciphertext
+ * @req: reference to the skcipher_request handle that holds all information
+ *       needed to perform the cipher operation
+ *
+ * Decrypt ciphertext data using the skcipher_request handle. That data
+ * structure and how it is filled with data is discussed with the
+ * skcipher_request_* functions.
+ *
+ * Return: 0 if the cipher operation was successful; < 0 if an error occurred
+ */
+static inline int crypto_skcipher_decrypt(struct skcipher_request *req)
+{
+        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+
+        return tfm->decrypt(req);
+}
+
+/**
+ * DOC: Symmetric Key Cipher Request Handle
+ *
+ * The skcipher_request data structure contains all pointers to data
+ * required for the symmetric key cipher operation. This includes the cipher
+ * handle (which can be used by multiple skcipher_request instances), pointer
+ * to plaintext and ciphertext, asynchronous callback function, etc. It acts
+ * as a handle to the skcipher_request_* API calls in a similar way as
+ * skcipher handle to the crypto_skcipher_* API calls.
+ */
+
+/**
+ * crypto_skcipher_reqsize() - obtain size of the request data structure
+ * @tfm: cipher handle
+ *
+ * Return: number of bytes
+ */
+static inline unsigned int crypto_skcipher_reqsize(struct crypto_skcipher *tfm)
+{
+        return tfm->reqsize;
+}
+
+/**
+ * skcipher_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 skcipher handle in the request
+ * data structure with a different one.
+ */
+static inline void skcipher_request_set_tfm(struct skcipher_request *req,
+                                            struct crypto_skcipher *tfm)
+{
+        req->base.tfm = crypto_skcipher_tfm(tfm);
+}
+
+static inline struct skcipher_request *skcipher_request_cast(
+        struct crypto_async_request *req)
+{
+        return container_of(req, struct skcipher_request, base);
+}
+
+/**
+ * skcipher_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 skcipher
+ * encrypt and decrypt API calls. During the allocation, the provided skcipher
+ * 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 skcipher_request *skcipher_request_alloc(
+        struct crypto_skcipher *tfm, gfp_t gfp)
+{
+        struct skcipher_request *req;
+
+        req = kmalloc(sizeof(struct skcipher_request) +
+                      crypto_skcipher_reqsize(tfm), gfp);
+
+        if (likely(req))
+                skcipher_request_set_tfm(req, tfm);
+
+        return req;
+}
+
+/**
+ * skcipher_request_free() - zeroize and free request data structure
+ * @req: request data structure cipher handle to be freed
+ */
+static inline void skcipher_request_free(struct skcipher_request *req)
+{
+        kzfree(req);
+}
+
+/**
+ * skcipher_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.
+ *
+ * This function allows setting the callback function that is triggered once the
+ * cipher operation completes.
+ *
+ * The callback function is registered with the skcipher_request handle and
+ * must comply with the following template
+ *
+ *      void callback_function(struct crypto_async_request *req, int error)
+ */
+static inline void skcipher_request_set_callback(struct skcipher_request *req,
+                                                 u32 flags,
+                                                 crypto_completion_t compl,
+                                                 void *data)
+{
+        req->base.complete = compl;
+        req->base.data = data;
+        req->base.flags = flags;
+}
+
+/**
+ * skcipher_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_skcipher_ivsize
+ *
+ * This function allows setting of the source data and destination data
+ * scatter / gather lists.
+ *
+ * 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.
+ */
+static inline void skcipher_request_set_crypt(
+        struct skcipher_request *req,
+        struct scatterlist *src, struct scatterlist *dst,
+        unsigned int cryptlen, void *iv)
+{
+        req->src = src;
+        req->dst = dst;
+        req->cryptlen = cryptlen;
+        req->iv = iv;
+}
+
 #endif  /* _CRYPTO_SKCIPHER_H */