/**
 * AES GCM routines supporting the Power 7+ Nest Accelerators driver
 *
 * Copyright (C) 2012 International Business Machines Inc.
 *
 * 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; version 2 only.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Author: Kent Yoder <yoder1@us.ibm.com>
 */

#include <crypto/internal/aead.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>
#include <linux/types.h>
#include <asm/vio.h>

#include "nx_csbcpb.h"
#include "nx.h"


static int gcm_aes_nx_set_key(struct crypto_aead *tfm,
                              const u8           *in_key,
                              unsigned int        key_len)
{
        struct nx_crypto_ctx *nx_ctx = crypto_aead_ctx(tfm);
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        struct nx_csbcpb *csbcpb_aead = nx_ctx->csbcpb_aead;

        nx_ctx_init(nx_ctx, HCOP_FC_AES);

        switch (key_len) {
        case AES_KEYSIZE_128:
                NX_CPB_SET_KEY_SIZE(csbcpb, NX_KS_AES_128);
                NX_CPB_SET_KEY_SIZE(csbcpb_aead, NX_KS_AES_128);
                nx_ctx->ap = &nx_ctx->props[NX_PROPS_AES_128];
                break;
        case AES_KEYSIZE_192:
                NX_CPB_SET_KEY_SIZE(csbcpb, NX_KS_AES_192);
                NX_CPB_SET_KEY_SIZE(csbcpb_aead, NX_KS_AES_192);
                nx_ctx->ap = &nx_ctx->props[NX_PROPS_AES_192];
                break;
        case AES_KEYSIZE_256:
                NX_CPB_SET_KEY_SIZE(csbcpb, NX_KS_AES_256);
                NX_CPB_SET_KEY_SIZE(csbcpb_aead, NX_KS_AES_256);
                nx_ctx->ap = &nx_ctx->props[NX_PROPS_AES_256];
                break;
        default:
                return -EINVAL;
        }

        csbcpb->cpb.hdr.mode = NX_MODE_AES_GCM;
        memcpy(csbcpb->cpb.aes_gcm.key, in_key, key_len);

        csbcpb_aead->cpb.hdr.mode = NX_MODE_AES_GCA;
        memcpy(csbcpb_aead->cpb.aes_gca.key, in_key, key_len);

        return 0;
}

static int gcm4106_aes_nx_set_key(struct crypto_aead *tfm,
                                  const u8           *in_key,
                                  unsigned int        key_len)
{
        struct nx_crypto_ctx *nx_ctx = crypto_aead_ctx(tfm);
        char *nonce = nx_ctx->priv.gcm.nonce;
        int rc;

        if (key_len < 4)
                return -EINVAL;

        key_len -= 4;

        rc = gcm_aes_nx_set_key(tfm, in_key, key_len);
        if (rc)
                goto out;

        memcpy(nonce, in_key + key_len, 4);
out:
        return rc;
}

static int gcm4106_aes_nx_setauthsize(struct crypto_aead *tfm,
                                      unsigned int authsize)
{
        switch (authsize) {
        case 8:
        case 12:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int nx_gca(struct nx_crypto_ctx  *nx_ctx,
                  struct aead_request   *req,
                  u8                    *out,
                  unsigned int assoclen)
{
        int rc;
        struct nx_csbcpb *csbcpb_aead = nx_ctx->csbcpb_aead;
        struct scatter_walk walk;
        struct nx_sg *nx_sg = nx_ctx->in_sg;
        unsigned int nbytes = assoclen;
        unsigned int processed = 0, to_process;
        unsigned int max_sg_len;

        if (nbytes <= AES_BLOCK_SIZE) {
                scatterwalk_start(&walk, req->src);
                scatterwalk_copychunks(out, &walk, nbytes, SCATTERWALK_FROM_SG);
                scatterwalk_done(&walk, SCATTERWALK_FROM_SG, 0);
                return 0;
        }

        NX_CPB_FDM(csbcpb_aead) &= ~NX_FDM_CONTINUATION;

        /* page_limit: number of sg entries that fit on one page */
        max_sg_len = min_t(u64, nx_driver.of.max_sg_len/sizeof(struct nx_sg),
                           nx_ctx->ap->sglen);
        max_sg_len = min_t(u64, max_sg_len,
                           nx_ctx->ap->databytelen/NX_PAGE_SIZE);

        do {
                /*
                 * to_process: the data chunk to process in this update.
                 * This value is bound by sg list limits.
                 */
                to_process = min_t(u64, nbytes - processed,
                                   nx_ctx->ap->databytelen);
                to_process = min_t(u64, to_process,
                                   NX_PAGE_SIZE * (max_sg_len - 1));

                nx_sg = nx_walk_and_build(nx_ctx->in_sg, max_sg_len,
                                          req->src, processed, &to_process);

                if ((to_process + processed) < nbytes)
                        NX_CPB_FDM(csbcpb_aead) |= NX_FDM_INTERMEDIATE;
                else
                        NX_CPB_FDM(csbcpb_aead) &= ~NX_FDM_INTERMEDIATE;

                nx_ctx->op_aead.inlen = (nx_ctx->in_sg - nx_sg)
                                        * sizeof(struct nx_sg);

                rc = nx_hcall_sync(nx_ctx, &nx_ctx->op_aead,
                                req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
                if (rc)
                        return rc;

                memcpy(csbcpb_aead->cpb.aes_gca.in_pat,
                                csbcpb_aead->cpb.aes_gca.out_pat,
                                AES_BLOCK_SIZE);
                NX_CPB_FDM(csbcpb_aead) |= NX_FDM_CONTINUATION;

                atomic_inc(&(nx_ctx->stats->aes_ops));
                atomic64_add(assoclen, &(nx_ctx->stats->aes_bytes));

                processed += to_process;
        } while (processed < nbytes);

        memcpy(out, csbcpb_aead->cpb.aes_gca.out_pat, AES_BLOCK_SIZE);

        return rc;
}

static int gmac(struct aead_request *req, struct blkcipher_desc *desc,
                unsigned int assoclen)
{
        int rc;
        struct nx_crypto_ctx *nx_ctx =
                crypto_aead_ctx(crypto_aead_reqtfm(req));
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        struct nx_sg *nx_sg;
        unsigned int nbytes = assoclen;
        unsigned int processed = 0, to_process;
        unsigned int max_sg_len;

        /* Set GMAC mode */
        csbcpb->cpb.hdr.mode = NX_MODE_AES_GMAC;

        NX_CPB_FDM(csbcpb) &= ~NX_FDM_CONTINUATION;

        /* page_limit: number of sg entries that fit on one page */
        max_sg_len = min_t(u64, nx_driver.of.max_sg_len/sizeof(struct nx_sg),
                           nx_ctx->ap->sglen);
        max_sg_len = min_t(u64, max_sg_len,
                           nx_ctx->ap->databytelen/NX_PAGE_SIZE);

        /* Copy IV */
        memcpy(csbcpb->cpb.aes_gcm.iv_or_cnt, desc->info, AES_BLOCK_SIZE);

        do {
                /*
                 * to_process: the data chunk to process in this update.
                 * This value is bound by sg list limits.
                 */
                to_process = min_t(u64, nbytes - processed,
                                   nx_ctx->ap->databytelen);
                to_process = min_t(u64, to_process,
                                   NX_PAGE_SIZE * (max_sg_len - 1));

                nx_sg = nx_walk_and_build(nx_ctx->in_sg, max_sg_len,
                                          req->src, processed, &to_process);

                if ((to_process + processed) < nbytes)
                        NX_CPB_FDM(csbcpb) |= NX_FDM_INTERMEDIATE;
                else
                        NX_CPB_FDM(csbcpb) &= ~NX_FDM_INTERMEDIATE;

                nx_ctx->op.inlen = (nx_ctx->in_sg - nx_sg)
                                        * sizeof(struct nx_sg);

                csbcpb->cpb.aes_gcm.bit_length_data = 0;
                csbcpb->cpb.aes_gcm.bit_length_aad = 8 * nbytes;

                rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
                                req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
                if (rc)
                        goto out;

                memcpy(csbcpb->cpb.aes_gcm.in_pat_or_aad,
                        csbcpb->cpb.aes_gcm.out_pat_or_mac, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_gcm.in_s0,
                        csbcpb->cpb.aes_gcm.out_s0, AES_BLOCK_SIZE);

                NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;

                atomic_inc(&(nx_ctx->stats->aes_ops));
                atomic64_add(assoclen, &(nx_ctx->stats->aes_bytes));

                processed += to_process;
        } while (processed < nbytes);

out:
        /* Restore GCM mode */
        csbcpb->cpb.hdr.mode = NX_MODE_AES_GCM;
        return rc;
}

static int gcm_empty(struct aead_request *req, struct blkcipher_desc *desc,
                     int enc)
{
        int rc;
        struct nx_crypto_ctx *nx_ctx =
                crypto_aead_ctx(crypto_aead_reqtfm(req));
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        char out[AES_BLOCK_SIZE];
        struct nx_sg *in_sg, *out_sg;
        int len;

        /* For scenarios where the input message is zero length, AES CTR mode
         * may be used. Set the source data to be a single block (16B) of all
         * zeros, and set the input IV value to be the same as the GMAC IV
         * value. - nx_wb 4.8.1.3 */

        /* Change to ECB mode */
        csbcpb->cpb.hdr.mode = NX_MODE_AES_ECB;
        memcpy(csbcpb->cpb.aes_ecb.key, csbcpb->cpb.aes_gcm.key,
                        sizeof(csbcpb->cpb.aes_ecb.key));
        if (enc)
                NX_CPB_FDM(csbcpb) |= NX_FDM_ENDE_ENCRYPT;
        else
                NX_CPB_FDM(csbcpb) &= ~NX_FDM_ENDE_ENCRYPT;

        len = AES_BLOCK_SIZE;

        /* Encrypt the counter/IV */
        in_sg = nx_build_sg_list(nx_ctx->in_sg, (u8 *) desc->info,
                                 &len, nx_ctx->ap->sglen);

        if (len != AES_BLOCK_SIZE)
                return -EINVAL;

        len = sizeof(out);
        out_sg = nx_build_sg_list(nx_ctx->out_sg, (u8 *) out, &len,
                                  nx_ctx->ap->sglen);

        if (len != sizeof(out))
                return -EINVAL;

        nx_ctx->op.inlen = (nx_ctx->in_sg - in_sg) * sizeof(struct nx_sg);
        nx_ctx->op.outlen = (nx_ctx->out_sg - out_sg) * sizeof(struct nx_sg);

        rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
                           desc->flags & CRYPTO_TFM_REQ_MAY_SLEEP);
        if (rc)
                goto out;
        atomic_inc(&(nx_ctx->stats->aes_ops));

        /* Copy out the auth tag */
        memcpy(csbcpb->cpb.aes_gcm.out_pat_or_mac, out,
                        crypto_aead_authsize(crypto_aead_reqtfm(req)));
out:
        /* Restore XCBC mode */
        csbcpb->cpb.hdr.mode = NX_MODE_AES_GCM;

        /*
         * ECB key uses the same region that GCM AAD and counter, so it's safe
         * to just fill it with zeroes.
         */
        memset(csbcpb->cpb.aes_ecb.key, 0, sizeof(csbcpb->cpb.aes_ecb.key));

        return rc;
}

static int gcm_aes_nx_crypt(struct aead_request *req, int enc,
                            unsigned int assoclen)
{
        struct nx_crypto_ctx *nx_ctx =
                crypto_aead_ctx(crypto_aead_reqtfm(req));
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        struct blkcipher_desc desc;
        unsigned int nbytes = req->cryptlen;
        unsigned int processed = 0, to_process;
        unsigned long irq_flags;
        int rc = -EINVAL;

        spin_lock_irqsave(&nx_ctx->lock, irq_flags);

        desc.info = rctx->iv;
        /* initialize the counter */
        *(u32 *)(desc.info + NX_GCM_CTR_OFFSET) = 1;

        if (nbytes == 0) {
                if (assoclen == 0)
                        rc = gcm_empty(req, &desc, enc);
                else
                        rc = gmac(req, &desc, assoclen);
                if (rc)
                        goto out;
                else
                        goto mac;
        }

        /* Process associated data */
        csbcpb->cpb.aes_gcm.bit_length_aad = assoclen * 8;
        if (assoclen) {
                rc = nx_gca(nx_ctx, req, csbcpb->cpb.aes_gcm.in_pat_or_aad,
                            assoclen);
                if (rc)
                        goto out;
        }

        /* Set flags for encryption */
        NX_CPB_FDM(csbcpb) &= ~NX_FDM_CONTINUATION;
        if (enc) {
                NX_CPB_FDM(csbcpb) |= NX_FDM_ENDE_ENCRYPT;
        } else {
                NX_CPB_FDM(csbcpb) &= ~NX_FDM_ENDE_ENCRYPT;
                nbytes -= crypto_aead_authsize(crypto_aead_reqtfm(req));
        }

        do {
                to_process = nbytes - processed;

                csbcpb->cpb.aes_gcm.bit_length_data = nbytes * 8;
                rc = nx_build_sg_lists(nx_ctx, &desc, req->dst,
                                       req->src, &to_process,
                                       processed + req->assoclen,
                                       csbcpb->cpb.aes_gcm.iv_or_cnt);

                if (rc)
                        goto out;

                if ((to_process + processed) < nbytes)
                        NX_CPB_FDM(csbcpb) |= NX_FDM_INTERMEDIATE;
                else
                        NX_CPB_FDM(csbcpb) &= ~NX_FDM_INTERMEDIATE;


                rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
                                   req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
                if (rc)
                        goto out;

                memcpy(desc.info, csbcpb->cpb.aes_gcm.out_cnt, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_gcm.in_pat_or_aad,
                        csbcpb->cpb.aes_gcm.out_pat_or_mac, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_gcm.in_s0,
                        csbcpb->cpb.aes_gcm.out_s0, AES_BLOCK_SIZE);

                NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;

                atomic_inc(&(nx_ctx->stats->aes_ops));
                atomic64_add(csbcpb->csb.processed_byte_count,
                             &(nx_ctx->stats->aes_bytes));

                processed += to_process;
        } while (processed < nbytes);

mac:
        if (enc) {
                /* copy out the auth tag */
                scatterwalk_map_and_copy(
                        csbcpb->cpb.aes_gcm.out_pat_or_mac,
                        req->dst, req->assoclen + nbytes,
                        crypto_aead_authsize(crypto_aead_reqtfm(req)),
                        SCATTERWALK_TO_SG);
        } else {
                u8 *itag = nx_ctx->priv.gcm.iauth_tag;
                u8 *otag = csbcpb->cpb.aes_gcm.out_pat_or_mac;

                scatterwalk_map_and_copy(
                        itag, req->src, req->assoclen + nbytes,
                        crypto_aead_authsize(crypto_aead_reqtfm(req)),
                        SCATTERWALK_FROM_SG);
                rc = crypto_memneq(itag, otag,
                            crypto_aead_authsize(crypto_aead_reqtfm(req))) ?
                     -EBADMSG : 0;
        }
out:
        spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
        return rc;
}

static int gcm_aes_nx_encrypt(struct aead_request *req)
{
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        char *iv = rctx->iv;

        memcpy(iv, req->iv, 12);

        return gcm_aes_nx_crypt(req, 1, req->assoclen);
}

static int gcm_aes_nx_decrypt(struct aead_request *req)
{
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        char *iv = rctx->iv;

        memcpy(iv, req->iv, 12);

        return gcm_aes_nx_crypt(req, 0, req->assoclen);
}

static int gcm4106_aes_nx_encrypt(struct aead_request *req)
{
        struct nx_crypto_ctx *nx_ctx =
                crypto_aead_ctx(crypto_aead_reqtfm(req));
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        char *iv = rctx->iv;
        char *nonce = nx_ctx->priv.gcm.nonce;

        memcpy(iv, nonce, NX_GCM4106_NONCE_LEN);
        memcpy(iv + NX_GCM4106_NONCE_LEN, req->iv, 8);

        if (req->assoclen < 8)
                return -EINVAL;

        return gcm_aes_nx_crypt(req, 1, req->assoclen - 8);
}

static int gcm4106_aes_nx_decrypt(struct aead_request *req)
{
        struct nx_crypto_ctx *nx_ctx =
                crypto_aead_ctx(crypto_aead_reqtfm(req));
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        char *iv = rctx->iv;
        char *nonce = nx_ctx->priv.gcm.nonce;

        memcpy(iv, nonce, NX_GCM4106_NONCE_LEN);
        memcpy(iv + NX_GCM4106_NONCE_LEN, req->iv, 8);

        if (req->assoclen < 8)
                return -EINVAL;

        return gcm_aes_nx_crypt(req, 0, req->assoclen - 8);
}

/* tell the block cipher walk routines that this is a stream cipher by
 * setting cra_blocksize to 1. Even using blkcipher_walk_virt_block
 * during encrypt/decrypt doesn't solve this problem, because it calls
 * blkcipher_walk_done under the covers, which doesn't use walk->blocksize,
 * but instead uses this tfm->blocksize. */
struct aead_alg nx_gcm_aes_alg = {
        .base = {
                .cra_name        = "gcm(aes)",
                .cra_driver_name = "gcm-aes-nx",
                .cra_priority    = 300,
                .cra_blocksize   = 1,
                .cra_ctxsize     = sizeof(struct nx_crypto_ctx),
                .cra_module      = THIS_MODULE,
        },
        .init        = nx_crypto_ctx_aes_gcm_init,
        .exit        = nx_crypto_ctx_aead_exit,
        .ivsize      = 12,
        .maxauthsize = AES_BLOCK_SIZE,
        .setkey      = gcm_aes_nx_set_key,
        .encrypt     = gcm_aes_nx_encrypt,
        .decrypt     = gcm_aes_nx_decrypt,
};

struct aead_alg nx_gcm4106_aes_alg = {
        .base = {
                .cra_name        = "rfc4106(gcm(aes))",
                .cra_driver_name = "rfc4106-gcm-aes-nx",
                .cra_priority    = 300,
                .cra_blocksize   = 1,
                .cra_ctxsize     = sizeof(struct nx_crypto_ctx),
                .cra_module      = THIS_MODULE,
        },
        .init        = nx_crypto_ctx_aes_gcm_init,
        .exit        = nx_crypto_ctx_aead_exit,
        .ivsize      = 8,
        .maxauthsize = AES_BLOCK_SIZE,
        .setkey      = gcm4106_aes_nx_set_key,
        .setauthsize = gcm4106_aes_nx_setauthsize,
        .encrypt     = gcm4106_aes_nx_encrypt,
        .decrypt     = gcm4106_aes_nx_decrypt,
};