// SPDX-License-Identifier: GPL-2.0+
/*
 * Cryptographic API.
 *
 * s390 implementation of the AES Cipher Algorithm.
 *
 * s390 Version:
 *   Copyright IBM Corp. 2005, 2017
 *   Author(s): Jan Glauber (jang@de.ibm.com)
 *              Sebastian Siewior (sebastian@breakpoint.cc> SW-Fallback
 *              Patrick Steuer <patrick.steuer@de.ibm.com>
 *              Harald Freudenberger <freude@de.ibm.com>
 *
 * Derived from "crypto/aes_generic.c"
 */

#define pr_fmt(fmt) "aes_s390: " fmt

#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/ghash.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/cpufeature.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/fips.h>
#include <linux/string.h>
#include <crypto/xts.h>
#include <asm/cpacf.h>

static u8 *ctrblk;
static DEFINE_MUTEX(ctrblk_lock);

static cpacf_mask_t km_functions, kmc_functions, kmctr_functions,
                    kma_functions;

struct s390_aes_ctx {
        u8 key[AES_MAX_KEY_SIZE];
        int key_len;
        unsigned long fc;
        union {
                struct crypto_skcipher *skcipher;
        } fallback;
};

struct s390_xts_ctx {
        union {
                u8 keys[64];
                struct {
                        u8 key[32];
                        u8 pcc_key[32];
                };
        };
        int key_len;
        unsigned long fc;
        struct crypto_skcipher *fallback;
};

struct gcm_sg_walk {
        struct scatter_walk walk;
        unsigned int walk_bytes;
        unsigned int walk_bytes_remain;
        u8 buf[AES_BLOCK_SIZE];
        unsigned int buf_bytes;
        u8 *ptr;
        unsigned int nbytes;
};

static int setkey_fallback_skcipher(struct crypto_skcipher *tfm, const u8 *key,
                                    unsigned int len)
{
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);

        crypto_skcipher_clear_flags(sctx->fallback.skcipher,
                                    CRYPTO_TFM_REQ_MASK);
        crypto_skcipher_set_flags(sctx->fallback.skcipher,
                                  crypto_skcipher_get_flags(tfm) &
                                  CRYPTO_TFM_REQ_MASK);
        return crypto_skcipher_setkey(sctx->fallback.skcipher, key, len);
}

static int fallback_skcipher_crypt(struct s390_aes_ctx *sctx,
                                   struct skcipher_request *req,
                                   unsigned long modifier)
{
        struct skcipher_request *subreq = skcipher_request_ctx(req);

        *subreq = *req;
        skcipher_request_set_tfm(subreq, sctx->fallback.skcipher);
        return (modifier & CPACF_DECRYPT) ?
                crypto_skcipher_decrypt(subreq) :
                crypto_skcipher_encrypt(subreq);
}

static int ecb_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
                           unsigned int key_len)
{
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        unsigned long fc;

        /* Pick the correct function code based on the key length */
        fc = (key_len == 16) ? CPACF_KM_AES_128 :
             (key_len == 24) ? CPACF_KM_AES_192 :
             (key_len == 32) ? CPACF_KM_AES_256 : 0;

        /* Check if the function code is available */
        sctx->fc = (fc && cpacf_test_func(&km_functions, fc)) ? fc : 0;
        if (!sctx->fc)
                return setkey_fallback_skcipher(tfm, in_key, key_len);

        sctx->key_len = key_len;
        memcpy(sctx->key, in_key, key_len);
        return 0;
}

static int ecb_aes_crypt(struct skcipher_request *req, unsigned long modifier)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes, n;
        int ret;

        if (unlikely(!sctx->fc))
                return fallback_skcipher_crypt(sctx, req, modifier);

        ret = skcipher_walk_virt(&walk, req, false);
        while ((nbytes = walk.nbytes) != 0) {
                /* only use complete blocks */
                n = nbytes & ~(AES_BLOCK_SIZE - 1);
                cpacf_km(sctx->fc | modifier, sctx->key,
                         walk.dst.virt.addr, walk.src.virt.addr, n);
                ret = skcipher_walk_done(&walk, nbytes - n);
        }
        return ret;
}

static int ecb_aes_encrypt(struct skcipher_request *req)
{
        return ecb_aes_crypt(req, 0);
}

static int ecb_aes_decrypt(struct skcipher_request *req)
{
        return ecb_aes_crypt(req, CPACF_DECRYPT);
}

static int fallback_init_skcipher(struct crypto_skcipher *tfm)
{
        const char *name = crypto_tfm_alg_name(&tfm->base);
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);

        sctx->fallback.skcipher = crypto_alloc_skcipher(name, 0,
                                CRYPTO_ALG_NEED_FALLBACK | CRYPTO_ALG_ASYNC);

        if (IS_ERR(sctx->fallback.skcipher)) {
                pr_err("Allocating AES fallback algorithm %s failed\n",
                       name);
                return PTR_ERR(sctx->fallback.skcipher);
        }

        crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
                                    crypto_skcipher_reqsize(sctx->fallback.skcipher));
        return 0;
}

static void fallback_exit_skcipher(struct crypto_skcipher *tfm)
{
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);

        crypto_free_skcipher(sctx->fallback.skcipher);
}

static struct skcipher_alg ecb_aes_alg = {
        .base.cra_name          =       "ecb(aes)",
        .base.cra_driver_name   =       "ecb-aes-s390",
        .base.cra_priority      =       401,    /* combo: aes + ecb + 1 */
        .base.cra_flags         =       CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct s390_aes_ctx),
        .base.cra_module        =       THIS_MODULE,
        .init                   =       fallback_init_skcipher,
        .exit                   =       fallback_exit_skcipher,
        .min_keysize            =       AES_MIN_KEY_SIZE,
        .max_keysize            =       AES_MAX_KEY_SIZE,
        .setkey                 =       ecb_aes_set_key,
        .encrypt                =       ecb_aes_encrypt,
        .decrypt                =       ecb_aes_decrypt,
};

static int cbc_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
                           unsigned int key_len)
{
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        unsigned long fc;

        /* Pick the correct function code based on the key length */
        fc = (key_len == 16) ? CPACF_KMC_AES_128 :
             (key_len == 24) ? CPACF_KMC_AES_192 :
             (key_len == 32) ? CPACF_KMC_AES_256 : 0;

        /* Check if the function code is available */
        sctx->fc = (fc && cpacf_test_func(&kmc_functions, fc)) ? fc : 0;
        if (!sctx->fc)
                return setkey_fallback_skcipher(tfm, in_key, key_len);

        sctx->key_len = key_len;
        memcpy(sctx->key, in_key, key_len);
        return 0;
}

static int cbc_aes_crypt(struct skcipher_request *req, unsigned long modifier)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes, n;
        int ret;
        struct {
                u8 iv[AES_BLOCK_SIZE];
                u8 key[AES_MAX_KEY_SIZE];
        } param;

        if (unlikely(!sctx->fc))
                return fallback_skcipher_crypt(sctx, req, modifier);

        ret = skcipher_walk_virt(&walk, req, false);
        if (ret)
                return ret;
        memcpy(param.iv, walk.iv, AES_BLOCK_SIZE);
        memcpy(param.key, sctx->key, sctx->key_len);
        while ((nbytes = walk.nbytes) != 0) {
                /* only use complete blocks */
                n = nbytes & ~(AES_BLOCK_SIZE - 1);
                cpacf_kmc(sctx->fc | modifier, &param,
                          walk.dst.virt.addr, walk.src.virt.addr, n);
                memcpy(walk.iv, param.iv, AES_BLOCK_SIZE);
                ret = skcipher_walk_done(&walk, nbytes - n);
        }
        memzero_explicit(&param, sizeof(param));
        return ret;
}

static int cbc_aes_encrypt(struct skcipher_request *req)
{
        return cbc_aes_crypt(req, 0);
}

static int cbc_aes_decrypt(struct skcipher_request *req)
{
        return cbc_aes_crypt(req, CPACF_DECRYPT);
}

static struct skcipher_alg cbc_aes_alg = {
        .base.cra_name          =       "cbc(aes)",
        .base.cra_driver_name   =       "cbc-aes-s390",
        .base.cra_priority      =       402,    /* ecb-aes-s390 + 1 */
        .base.cra_flags         =       CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct s390_aes_ctx),
        .base.cra_module        =       THIS_MODULE,
        .init                   =       fallback_init_skcipher,
        .exit                   =       fallback_exit_skcipher,
        .min_keysize            =       AES_MIN_KEY_SIZE,
        .max_keysize            =       AES_MAX_KEY_SIZE,
        .ivsize                 =       AES_BLOCK_SIZE,
        .setkey                 =       cbc_aes_set_key,
        .encrypt                =       cbc_aes_encrypt,
        .decrypt                =       cbc_aes_decrypt,
};

static int xts_fallback_setkey(struct crypto_skcipher *tfm, const u8 *key,
                               unsigned int len)
{
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);

        crypto_skcipher_clear_flags(xts_ctx->fallback, CRYPTO_TFM_REQ_MASK);
        crypto_skcipher_set_flags(xts_ctx->fallback,
                                  crypto_skcipher_get_flags(tfm) &
                                  CRYPTO_TFM_REQ_MASK);
        return crypto_skcipher_setkey(xts_ctx->fallback, key, len);
}

static int xts_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
                           unsigned int key_len)
{
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);
        unsigned long fc;
        int err;

        err = xts_fallback_setkey(tfm, in_key, key_len);
        if (err)
                return err;

        /* Pick the correct function code based on the key length */
        fc = (key_len == 32) ? CPACF_KM_XTS_128 :
             (key_len == 64) ? CPACF_KM_XTS_256 : 0;

        /* Check if the function code is available */
        xts_ctx->fc = (fc && cpacf_test_func(&km_functions, fc)) ? fc : 0;
        if (!xts_ctx->fc)
                return 0;

        /* Split the XTS key into the two subkeys */
        key_len = key_len / 2;
        xts_ctx->key_len = key_len;
        memcpy(xts_ctx->key, in_key, key_len);
        memcpy(xts_ctx->pcc_key, in_key + key_len, key_len);
        return 0;
}

static int xts_aes_crypt(struct skcipher_request *req, unsigned long modifier)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int offset, nbytes, n;
        int ret;
        struct {
                u8 key[32];
                u8 tweak[16];
                u8 block[16];
                u8 bit[16];
                u8 xts[16];
        } pcc_param;
        struct {
                u8 key[32];
                u8 init[16];
        } xts_param;

        if (req->cryptlen < AES_BLOCK_SIZE)
                return -EINVAL;

        if (unlikely(!xts_ctx->fc || (req->cryptlen % AES_BLOCK_SIZE) != 0)) {
                struct skcipher_request *subreq = skcipher_request_ctx(req);

                *subreq = *req;
                skcipher_request_set_tfm(subreq, xts_ctx->fallback);
                return (modifier & CPACF_DECRYPT) ?
                        crypto_skcipher_decrypt(subreq) :
                        crypto_skcipher_encrypt(subreq);
        }

        ret = skcipher_walk_virt(&walk, req, false);
        if (ret)
                return ret;
        offset = xts_ctx->key_len & 0x10;
        memset(pcc_param.block, 0, sizeof(pcc_param.block));
        memset(pcc_param.bit, 0, sizeof(pcc_param.bit));
        memset(pcc_param.xts, 0, sizeof(pcc_param.xts));
        memcpy(pcc_param.tweak, walk.iv, sizeof(pcc_param.tweak));
        memcpy(pcc_param.key + offset, xts_ctx->pcc_key, xts_ctx->key_len);
        cpacf_pcc(xts_ctx->fc, pcc_param.key + offset);

        memcpy(xts_param.key + offset, xts_ctx->key, xts_ctx->key_len);
        memcpy(xts_param.init, pcc_param.xts, 16);

        while ((nbytes = walk.nbytes) != 0) {
                /* only use complete blocks */
                n = nbytes & ~(AES_BLOCK_SIZE - 1);
                cpacf_km(xts_ctx->fc | modifier, xts_param.key + offset,
                         walk.dst.virt.addr, walk.src.virt.addr, n);
                ret = skcipher_walk_done(&walk, nbytes - n);
        }
        memzero_explicit(&pcc_param, sizeof(pcc_param));
        memzero_explicit(&xts_param, sizeof(xts_param));
        return ret;
}

static int xts_aes_encrypt(struct skcipher_request *req)
{
        return xts_aes_crypt(req, 0);
}

static int xts_aes_decrypt(struct skcipher_request *req)
{
        return xts_aes_crypt(req, CPACF_DECRYPT);
}

static int xts_fallback_init(struct crypto_skcipher *tfm)
{
        const char *name = crypto_tfm_alg_name(&tfm->base);
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);

        xts_ctx->fallback = crypto_alloc_skcipher(name, 0,
                                CRYPTO_ALG_NEED_FALLBACK | CRYPTO_ALG_ASYNC);

        if (IS_ERR(xts_ctx->fallback)) {
                pr_err("Allocating XTS fallback algorithm %s failed\n",
                       name);
                return PTR_ERR(xts_ctx->fallback);
        }
        crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
                                    crypto_skcipher_reqsize(xts_ctx->fallback));
        return 0;
}

static void xts_fallback_exit(struct crypto_skcipher *tfm)
{
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);

        crypto_free_skcipher(xts_ctx->fallback);
}

static struct skcipher_alg xts_aes_alg = {
        .base.cra_name          =       "xts(aes)",
        .base.cra_driver_name   =       "xts-aes-s390",
        .base.cra_priority      =       402,    /* ecb-aes-s390 + 1 */
        .base.cra_flags         =       CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct s390_xts_ctx),
        .base.cra_module        =       THIS_MODULE,
        .init                   =       xts_fallback_init,
        .exit                   =       xts_fallback_exit,
        .min_keysize            =       2 * AES_MIN_KEY_SIZE,
        .max_keysize            =       2 * AES_MAX_KEY_SIZE,
        .ivsize                 =       AES_BLOCK_SIZE,
        .setkey                 =       xts_aes_set_key,
        .encrypt                =       xts_aes_encrypt,
        .decrypt                =       xts_aes_decrypt,
};

static int fullxts_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
                               unsigned int key_len)
{
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);
        unsigned long fc;
        int err;

        err = xts_fallback_setkey(tfm, in_key, key_len);
        if (err)
                return err;

        /* Pick the correct function code based on the key length */
        fc = (key_len == 32) ? CPACF_KM_XTS_128_FULL :
             (key_len == 64) ? CPACF_KM_XTS_256_FULL : 0;

        /* Check if the function code is available */
        xts_ctx->fc = (fc && cpacf_test_func(&km_functions, fc)) ? fc : 0;
        if (!xts_ctx->fc)
                return 0;

        /* Store double-key */
        memcpy(xts_ctx->keys, in_key, key_len);
        xts_ctx->key_len = key_len;
        return 0;
}

static int fullxts_aes_crypt(struct skcipher_request *req,  unsigned long modifier)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct s390_xts_ctx *xts_ctx = crypto_skcipher_ctx(tfm);
        unsigned int offset, nbytes, n;
        struct skcipher_walk walk;
        int ret;
        struct {
                __u8 key[64];
                __u8 tweak[16];
                __u8 nap[16];
        } fxts_param = {
                .nap = {0},
        };

        if (req->cryptlen < AES_BLOCK_SIZE)
                return -EINVAL;

        if (unlikely(!xts_ctx->fc || (req->cryptlen % AES_BLOCK_SIZE) != 0)) {
                struct skcipher_request *subreq = skcipher_request_ctx(req);

                *subreq = *req;
                skcipher_request_set_tfm(subreq, xts_ctx->fallback);
                return (modifier & CPACF_DECRYPT) ?
                        crypto_skcipher_decrypt(subreq) :
                        crypto_skcipher_encrypt(subreq);
        }

        ret = skcipher_walk_virt(&walk, req, false);
        if (ret)
                return ret;

        offset = xts_ctx->key_len & 0x20;
        memcpy(fxts_param.key + offset, xts_ctx->keys, xts_ctx->key_len);
        memcpy(fxts_param.tweak, req->iv, AES_BLOCK_SIZE);
        fxts_param.nap[0] = 0x01; /* initial alpha power (1, little-endian) */

        while ((nbytes = walk.nbytes) != 0) {
                /* only use complete blocks */
                n = nbytes & ~(AES_BLOCK_SIZE - 1);
                cpacf_km(xts_ctx->fc | modifier, fxts_param.key + offset,
                         walk.dst.virt.addr, walk.src.virt.addr, n);
                ret = skcipher_walk_done(&walk, nbytes - n);
        }
        memzero_explicit(&fxts_param, sizeof(fxts_param));
        return ret;
}

static int fullxts_aes_encrypt(struct skcipher_request *req)
{
        return fullxts_aes_crypt(req, 0);
}

static int fullxts_aes_decrypt(struct skcipher_request *req)
{
        return fullxts_aes_crypt(req, CPACF_DECRYPT);
}

static struct skcipher_alg fullxts_aes_alg = {
        .base.cra_name          =       "xts(aes)",
        .base.cra_driver_name   =       "full-xts-aes-s390",
        .base.cra_priority      =       403,    /* aes-xts-s390 + 1 */
        .base.cra_flags         =       CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct s390_xts_ctx),
        .base.cra_module        =       THIS_MODULE,
        .init                   =       xts_fallback_init,
        .exit                   =       xts_fallback_exit,
        .min_keysize            =       2 * AES_MIN_KEY_SIZE,
        .max_keysize            =       2 * AES_MAX_KEY_SIZE,
        .ivsize                 =       AES_BLOCK_SIZE,
        .setkey                 =       fullxts_aes_set_key,
        .encrypt                =       fullxts_aes_encrypt,
        .decrypt                =       fullxts_aes_decrypt,
};

static int ctr_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
                           unsigned int key_len)
{
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        unsigned long fc;

        /* Pick the correct function code based on the key length */
        fc = (key_len == 16) ? CPACF_KMCTR_AES_128 :
             (key_len == 24) ? CPACF_KMCTR_AES_192 :
             (key_len == 32) ? CPACF_KMCTR_AES_256 : 0;

        /* Check if the function code is available */
        sctx->fc = (fc && cpacf_test_func(&kmctr_functions, fc)) ? fc : 0;
        if (!sctx->fc)
                return setkey_fallback_skcipher(tfm, in_key, key_len);

        sctx->key_len = key_len;
        memcpy(sctx->key, in_key, key_len);
        return 0;
}

static unsigned int __ctrblk_init(u8 *ctrptr, u8 *iv, unsigned int nbytes)
{
        unsigned int i, n;

        /* only use complete blocks, max. PAGE_SIZE */
        memcpy(ctrptr, iv, AES_BLOCK_SIZE);
        n = (nbytes > PAGE_SIZE) ? PAGE_SIZE : nbytes & ~(AES_BLOCK_SIZE - 1);
        for (i = (n / AES_BLOCK_SIZE) - 1; i > 0; i--) {
                memcpy(ctrptr + AES_BLOCK_SIZE, ctrptr, AES_BLOCK_SIZE);
                crypto_inc(ctrptr + AES_BLOCK_SIZE, AES_BLOCK_SIZE);
                ctrptr += AES_BLOCK_SIZE;
        }
        return n;
}

static int ctr_aes_crypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm);
        u8 buf[AES_BLOCK_SIZE], *ctrptr;
        struct skcipher_walk walk;
        unsigned int n, nbytes;
        int ret, locked;

        if (unlikely(!sctx->fc))
                return fallback_skcipher_crypt(sctx, req, 0);

        locked = mutex_trylock(&ctrblk_lock);

        ret = skcipher_walk_virt(&walk, req, false);
        while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
                n = AES_BLOCK_SIZE;

                if (nbytes >= 2*AES_BLOCK_SIZE && locked)
                        n = __ctrblk_init(ctrblk, walk.iv, nbytes);
                ctrptr = (n > AES_BLOCK_SIZE) ? ctrblk : walk.iv;
                cpacf_kmctr(sctx->fc, sctx->key, walk.dst.virt.addr,
                            walk.src.virt.addr, n, ctrptr);
                if (ctrptr == ctrblk)
                        memcpy(walk.iv, ctrptr + n - AES_BLOCK_SIZE,
                               AES_BLOCK_SIZE);
                crypto_inc(walk.iv, AES_BLOCK_SIZE);
                ret = skcipher_walk_done(&walk, nbytes - n);
        }
        if (locked)
                mutex_unlock(&ctrblk_lock);
        /*
         * final block may be < AES_BLOCK_SIZE, copy only nbytes
         */
        if (nbytes) {
                memset(buf, 0, AES_BLOCK_SIZE);
                memcpy(buf, walk.src.virt.addr, nbytes);
                cpacf_kmctr(sctx->fc, sctx->key, buf, buf,
                            AES_BLOCK_SIZE, walk.iv);
                memcpy(walk.dst.virt.addr, buf, nbytes);
                crypto_inc(walk.iv, AES_BLOCK_SIZE);
                ret = skcipher_walk_done(&walk, 0);
        }

        return ret;
}

static struct skcipher_alg ctr_aes_alg = {
        .base.cra_name          =       "ctr(aes)",
        .base.cra_driver_name   =       "ctr-aes-s390",
        .base.cra_priority      =       402,    /* ecb-aes-s390 + 1 */
        .base.cra_flags         =       CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize     =       1,
        .base.cra_ctxsize       =       sizeof(struct s390_aes_ctx),
        .base.cra_module        =       THIS_MODULE,
        .init                   =       fallback_init_skcipher,
        .exit                   =       fallback_exit_skcipher,
        .min_keysize            =       AES_MIN_KEY_SIZE,
        .max_keysize            =       AES_MAX_KEY_SIZE,
        .ivsize                 =       AES_BLOCK_SIZE,
        .setkey                 =       ctr_aes_set_key,
        .encrypt                =       ctr_aes_crypt,
        .decrypt                =       ctr_aes_crypt,
        .chunksize              =       AES_BLOCK_SIZE,
};

static int gcm_aes_setkey(struct crypto_aead *tfm, const u8 *key,
                          unsigned int keylen)
{
        struct s390_aes_ctx *ctx = crypto_aead_ctx(tfm);

        switch (keylen) {
        case AES_KEYSIZE_128:
                ctx->fc = CPACF_KMA_GCM_AES_128;
                break;
        case AES_KEYSIZE_192:
                ctx->fc = CPACF_KMA_GCM_AES_192;
                break;
        case AES_KEYSIZE_256:
                ctx->fc = CPACF_KMA_GCM_AES_256;
                break;
        default:
                return -EINVAL;
        }

        memcpy(ctx->key, key, keylen);
        ctx->key_len = keylen;
        return 0;
}

static int gcm_aes_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
        switch (authsize) {
        case 4:
        case 8:
        case 12:
        case 13:
        case 14:
        case 15:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static void gcm_walk_start(struct gcm_sg_walk *gw, struct scatterlist *sg,
                           unsigned int len)
{
        memset(gw, 0, sizeof(*gw));
        gw->walk_bytes_remain = len;
        scatterwalk_start(&gw->walk, sg);
}

static inline unsigned int _gcm_sg_clamp_and_map(struct gcm_sg_walk *gw)
{
        if (gw->walk_bytes_remain == 0)
                return 0;
        gw->walk_bytes = scatterwalk_next(&gw->walk, gw->walk_bytes_remain);
        return gw->walk_bytes;
}

static inline void _gcm_sg_unmap_and_advance(struct gcm_sg_walk *gw,
                                             unsigned int nbytes, bool out)
{
        gw->walk_bytes_remain -= nbytes;
        if (out)
                scatterwalk_done_dst(&gw->walk, nbytes);
        else
                scatterwalk_done_src(&gw->walk, nbytes);
}

static int gcm_in_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
{
        int n;

        if (gw->buf_bytes && gw->buf_bytes >= minbytesneeded) {
                gw->ptr = gw->buf;
                gw->nbytes = gw->buf_bytes;
                goto out;
        }

        if (gw->walk_bytes_remain == 0) {
                gw->ptr = NULL;
                gw->nbytes = 0;
                goto out;
        }

        if (!_gcm_sg_clamp_and_map(gw)) {
                gw->ptr = NULL;
                gw->nbytes = 0;
                goto out;
        }

        if (!gw->buf_bytes && gw->walk_bytes >= minbytesneeded) {
                gw->ptr = gw->walk.addr;
                gw->nbytes = gw->walk_bytes;
                goto out;
        }

        while (1) {
                n = min(gw->walk_bytes, AES_BLOCK_SIZE - gw->buf_bytes);
                memcpy(gw->buf + gw->buf_bytes, gw->walk.addr, n);
                gw->buf_bytes += n;
                _gcm_sg_unmap_and_advance(gw, n, false);
                if (gw->buf_bytes >= minbytesneeded) {
                        gw->ptr = gw->buf;
                        gw->nbytes = gw->buf_bytes;
                        goto out;
                }
                if (!_gcm_sg_clamp_and_map(gw)) {
                        gw->ptr = NULL;
                        gw->nbytes = 0;
                        goto out;
                }
        }

out:
        return gw->nbytes;
}

static int gcm_out_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
{
        if (gw->walk_bytes_remain == 0) {
                gw->ptr = NULL;
                gw->nbytes = 0;
                goto out;
        }

        if (!_gcm_sg_clamp_and_map(gw)) {
                gw->ptr = NULL;
                gw->nbytes = 0;
                goto out;
        }

        if (gw->walk_bytes >= minbytesneeded) {
                gw->ptr = gw->walk.addr;
                gw->nbytes = gw->walk_bytes;
                goto out;
        }

        scatterwalk_unmap(&gw->walk);

        gw->ptr = gw->buf;
        gw->nbytes = sizeof(gw->buf);

out:
        return gw->nbytes;
}

static int gcm_in_walk_done(struct gcm_sg_walk *gw, unsigned int bytesdone)
{
        if (gw->ptr == NULL)
                return 0;

        if (gw->ptr == gw->buf) {
                int n = gw->buf_bytes - bytesdone;
                if (n > 0) {
                        memmove(gw->buf, gw->buf + bytesdone, n);
                        gw->buf_bytes = n;
                } else
                        gw->buf_bytes = 0;
        } else
                _gcm_sg_unmap_and_advance(gw, bytesdone, false);

        return bytesdone;
}

static int gcm_out_walk_done(struct gcm_sg_walk *gw, unsigned int bytesdone)
{
        int i, n;

        if (gw->ptr == NULL)
                return 0;

        if (gw->ptr == gw->buf) {
                for (i = 0; i < bytesdone; i += n) {
                        if (!_gcm_sg_clamp_and_map(gw))
                                return i;
                        n = min(gw->walk_bytes, bytesdone - i);
                        memcpy(gw->walk.addr, gw->buf + i, n);
                        _gcm_sg_unmap_and_advance(gw, n, true);
                }
        } else
                _gcm_sg_unmap_and_advance(gw, bytesdone, true);

        return bytesdone;
}

static int gcm_aes_crypt(struct aead_request *req, unsigned int flags)
{
        struct crypto_aead *tfm = crypto_aead_reqtfm(req);
        struct s390_aes_ctx *ctx = crypto_aead_ctx(tfm);
        unsigned int ivsize = crypto_aead_ivsize(tfm);
        unsigned int taglen = crypto_aead_authsize(tfm);
        unsigned int aadlen = req->assoclen;
        unsigned int pclen = req->cryptlen;
        int ret = 0;

        unsigned int n, len, in_bytes, out_bytes,
                     min_bytes, bytes, aad_bytes, pc_bytes;
        struct gcm_sg_walk gw_in, gw_out;
        u8 tag[GHASH_DIGEST_SIZE];

        struct {
                u32 _[3];               /* reserved */
                u32 cv;                 /* Counter Value */
                u8 t[GHASH_DIGEST_SIZE];/* Tag */
                u8 h[AES_BLOCK_SIZE];   /* Hash-subkey */
                u64 taadl;              /* Total AAD Length */
                u64 tpcl;               /* Total Plain-/Cipher-text Length */
                u8 j0[GHASH_BLOCK_SIZE];/* initial counter value */
                u8 k[AES_MAX_KEY_SIZE]; /* Key */
        } param;

        /*
         * encrypt
         *   req->src: aad||plaintext
         *   req->dst: aad||ciphertext||tag
         * decrypt
         *   req->src: aad||ciphertext||tag
         *   req->dst: aad||plaintext, return 0 or -EBADMSG
         * aad, plaintext and ciphertext may be empty.
         */
        if (flags & CPACF_DECRYPT)
                pclen -= taglen;
        len = aadlen + pclen;

        memset(&param, 0, sizeof(param));
        param.cv = 1;
        param.taadl = aadlen * 8;
        param.tpcl = pclen * 8;
        memcpy(param.j0, req->iv, ivsize);
        *(u32 *)(param.j0 + ivsize) = 1;
        memcpy(param.k, ctx->key, ctx->key_len);

        gcm_walk_start(&gw_in, req->src, len);
        gcm_walk_start(&gw_out, req->dst, len);

        do {
                min_bytes = min_t(unsigned int,
                                  aadlen > 0 ? aadlen : pclen, AES_BLOCK_SIZE);
                in_bytes = gcm_in_walk_go(&gw_in, min_bytes);
                out_bytes = gcm_out_walk_go(&gw_out, min_bytes);
                bytes = min(in_bytes, out_bytes);

                if (aadlen + pclen <= bytes) {
                        aad_bytes = aadlen;
                        pc_bytes = pclen;
                        flags |= CPACF_KMA_LAAD | CPACF_KMA_LPC;
                } else {
                        if (aadlen <= bytes) {
                                aad_bytes = aadlen;
                                pc_bytes = (bytes - aadlen) &
                                           ~(AES_BLOCK_SIZE - 1);
                                flags |= CPACF_KMA_LAAD;
                        } else {
                                aad_bytes = bytes & ~(AES_BLOCK_SIZE - 1);
                                pc_bytes = 0;
                        }
                }

                if (aad_bytes > 0)
                        memcpy(gw_out.ptr, gw_in.ptr, aad_bytes);

                cpacf_kma(ctx->fc | flags, &param,
                          gw_out.ptr + aad_bytes,
                          gw_in.ptr + aad_bytes, pc_bytes,
                          gw_in.ptr, aad_bytes);

                n = aad_bytes + pc_bytes;
                if (gcm_in_walk_done(&gw_in, n) != n)
                        return -ENOMEM;
                if (gcm_out_walk_done(&gw_out, n) != n)
                        return -ENOMEM;
                aadlen -= aad_bytes;
                pclen -= pc_bytes;
        } while (aadlen + pclen > 0);

        if (flags & CPACF_DECRYPT) {
                scatterwalk_map_and_copy(tag, req->src, len, taglen, 0);
                if (crypto_memneq(tag, param.t, taglen))
                        ret = -EBADMSG;
        } else
                scatterwalk_map_and_copy(param.t, req->dst, len, taglen, 1);

        memzero_explicit(&param, sizeof(param));
        return ret;
}

static int gcm_aes_encrypt(struct aead_request *req)
{
        return gcm_aes_crypt(req, CPACF_ENCRYPT);
}

static int gcm_aes_decrypt(struct aead_request *req)
{
        return gcm_aes_crypt(req, CPACF_DECRYPT);
}

static struct aead_alg gcm_aes_aead = {
        .setkey                 = gcm_aes_setkey,
        .setauthsize            = gcm_aes_setauthsize,
        .encrypt                = gcm_aes_encrypt,
        .decrypt                = gcm_aes_decrypt,

        .ivsize                 = GHASH_BLOCK_SIZE - sizeof(u32),
        .maxauthsize            = GHASH_DIGEST_SIZE,
        .chunksize              = AES_BLOCK_SIZE,

        .base                   = {
                .cra_blocksize          = 1,
                .cra_ctxsize            = sizeof(struct s390_aes_ctx),
                .cra_priority           = 900,
                .cra_name               = "gcm(aes)",
                .cra_driver_name        = "gcm-aes-s390",
                .cra_module             = THIS_MODULE,
        },
};

static struct skcipher_alg *aes_s390_skcipher_algs[5];
static int aes_s390_skciphers_num;
static struct aead_alg *aes_s390_aead_alg;

static int aes_s390_register_skcipher(struct skcipher_alg *alg)
{
        int ret;

        ret = crypto_register_skcipher(alg);
        if (!ret)
                aes_s390_skcipher_algs[aes_s390_skciphers_num++] = alg;
        return ret;
}

static void aes_s390_fini(void)
{
        while (aes_s390_skciphers_num--)
                crypto_unregister_skcipher(aes_s390_skcipher_algs[aes_s390_skciphers_num]);
        if (ctrblk)
                free_page((unsigned long) ctrblk);

        if (aes_s390_aead_alg)
                crypto_unregister_aead(aes_s390_aead_alg);
}

static int __init aes_s390_init(void)
{
        int ret;

        /* Query available functions for KM, KMC, KMCTR and KMA */
        cpacf_query(CPACF_KM, &km_functions);
        cpacf_query(CPACF_KMC, &kmc_functions);
        cpacf_query(CPACF_KMCTR, &kmctr_functions);
        cpacf_query(CPACF_KMA, &kma_functions);

        if (cpacf_test_func(&km_functions, CPACF_KM_AES_128) ||
            cpacf_test_func(&km_functions, CPACF_KM_AES_192) ||
            cpacf_test_func(&km_functions, CPACF_KM_AES_256)) {
                ret = aes_s390_register_skcipher(&ecb_aes_alg);
                if (ret)
                        goto out_err;
        }

        if (cpacf_test_func(&kmc_functions, CPACF_KMC_AES_128) ||
            cpacf_test_func(&kmc_functions, CPACF_KMC_AES_192) ||
            cpacf_test_func(&kmc_functions, CPACF_KMC_AES_256)) {
                ret = aes_s390_register_skcipher(&cbc_aes_alg);
                if (ret)
                        goto out_err;
        }

        if (cpacf_test_func(&km_functions, CPACF_KM_XTS_128_FULL) ||
            cpacf_test_func(&km_functions, CPACF_KM_XTS_256_FULL)) {
                ret = aes_s390_register_skcipher(&fullxts_aes_alg);
                if (ret)
                        goto out_err;
        }

        if (cpacf_test_func(&km_functions, CPACF_KM_XTS_128) ||
            cpacf_test_func(&km_functions, CPACF_KM_XTS_256)) {
                ret = aes_s390_register_skcipher(&xts_aes_alg);
                if (ret)
                        goto out_err;
        }

        if (cpacf_test_func(&kmctr_functions, CPACF_KMCTR_AES_128) ||
            cpacf_test_func(&kmctr_functions, CPACF_KMCTR_AES_192) ||
            cpacf_test_func(&kmctr_functions, CPACF_KMCTR_AES_256)) {
                ctrblk = (u8 *) __get_free_page(GFP_KERNEL);
                if (!ctrblk) {
                        ret = -ENOMEM;
                        goto out_err;
                }
                ret = aes_s390_register_skcipher(&ctr_aes_alg);
                if (ret)
                        goto out_err;
        }

        if (cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_128) ||
            cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_192) ||
            cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_256)) {
                ret = crypto_register_aead(&gcm_aes_aead);
                if (ret)
                        goto out_err;
                aes_s390_aead_alg = &gcm_aes_aead;
        }

        return 0;
out_err:
        aes_s390_fini();
        return ret;
}

module_cpu_feature_match(S390_CPU_FEATURE_MSA, aes_s390_init);
module_exit(aes_s390_fini);

MODULE_ALIAS_CRYPTO("aes-all");

MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
MODULE_LICENSE("GPL");