/**
 * AES CCM 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 <linux/crypto.h>
#include <asm/vio.h>

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


static int ccm_aes_nx_set_key(struct crypto_aead *tfm,
                              const u8           *in_key,
                              unsigned int        key_len)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(&tfm->base);
        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;
        default:
                return -EINVAL;
        }

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

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

        return 0;

}

static int ccm4309_aes_nx_set_key(struct crypto_aead *tfm,
                                  const u8           *in_key,
                                  unsigned int        key_len)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(&tfm->base);

        if (key_len < 3)
                return -EINVAL;

        key_len -= 3;

        memcpy(nx_ctx->priv.ccm.nonce, in_key + key_len, 3);

        return ccm_aes_nx_set_key(tfm, in_key, key_len);
}

static int ccm_aes_nx_setauthsize(struct crypto_aead *tfm,
                                  unsigned int authsize)
{
        switch (authsize) {
        case 4:
        case 6:
        case 8:
        case 10:
        case 12:
        case 14:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int ccm4309_aes_nx_setauthsize(struct crypto_aead *tfm,
                                      unsigned int authsize)
{
        switch (authsize) {
        case 8:
        case 12:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

/* taken from crypto/ccm.c */
static int set_msg_len(u8 *block, unsigned int msglen, int csize)
{
        __be32 data;

        memset(block, 0, csize);
        block += csize;

        if (csize >= 4)
                csize = 4;
        else if (msglen > (unsigned int)(1 << (8 * csize)))
                return -EOVERFLOW;

        data = cpu_to_be32(msglen);
        memcpy(block - csize, (u8 *)&data + 4 - csize, csize);

        return 0;
}

/* taken from crypto/ccm.c */
static inline int crypto_ccm_check_iv(const u8 *iv)
{
        /* 2 <= L <= 8, so 1 <= L' <= 7. */
        if (1 > iv[0] || iv[0] > 7)
                return -EINVAL;

        return 0;
}

/* based on code from crypto/ccm.c */
static int generate_b0(u8 *iv, unsigned int assoclen, unsigned int authsize,
                       unsigned int cryptlen, u8 *b0)
{
        unsigned int l, lp, m = authsize;
        int rc;

        memcpy(b0, iv, 16);

        lp = b0[0];
        l = lp + 1;

        /* set m, bits 3-5 */
        *b0 |= (8 * ((m - 2) / 2));

        /* set adata, bit 6, if associated data is used */
        if (assoclen)
                *b0 |= 64;

        rc = set_msg_len(b0 + 16 - l, cryptlen, l);

        return rc;
}

static int generate_pat(u8                   *iv,
                        struct aead_request  *req,
                        struct nx_crypto_ctx *nx_ctx,
                        unsigned int          authsize,
                        unsigned int          nbytes,
                        unsigned int          assoclen,
                        u8                   *out)
{
        struct nx_sg *nx_insg = nx_ctx->in_sg;
        struct nx_sg *nx_outsg = nx_ctx->out_sg;
        unsigned int iauth_len = 0;
        u8 tmp[16], *b1 = NULL, *b0 = NULL, *result = NULL;
        int rc;
        unsigned int max_sg_len;

        /* zero the ctr value */
        memset(iv + 15 - iv[0], 0, iv[0] + 1);

        /* page 78 of nx_wb.pdf has,
         * Note: RFC3610 allows the AAD data to be up to 2^64 -1 bytes
         * in length. If a full message is used, the AES CCA implementation
         * restricts the maximum AAD length to 2^32 -1 bytes.
         * If partial messages are used, the implementation supports
         * 2^64 -1 bytes maximum AAD length.
         *
         * However, in the cryptoapi's aead_request structure,
         * assoclen is an unsigned int, thus it cannot hold a length
         * value greater than 2^32 - 1.
         * Thus the AAD is further constrained by this and is never
         * greater than 2^32.
         */

        if (!assoclen) {
                b0 = nx_ctx->csbcpb->cpb.aes_ccm.in_pat_or_b0;
        } else if (assoclen <= 14) {
                /* if associated data is 14 bytes or less, we do 1 GCM
                 * operation on 2 AES blocks, B0 (stored in the csbcpb) and B1,
                 * which is fed in through the source buffers here */
                b0 = nx_ctx->csbcpb->cpb.aes_ccm.in_pat_or_b0;
                b1 = nx_ctx->priv.ccm.iauth_tag;
                iauth_len = assoclen;
        } else if (assoclen <= 65280) {
                /* if associated data is less than (2^16 - 2^8), we construct
                 * B1 differently and feed in the associated data to a CCA
                 * operation */
                b0 = nx_ctx->csbcpb_aead->cpb.aes_cca.b0;
                b1 = nx_ctx->csbcpb_aead->cpb.aes_cca.b1;
                iauth_len = 14;
        } else {
                b0 = nx_ctx->csbcpb_aead->cpb.aes_cca.b0;
                b1 = nx_ctx->csbcpb_aead->cpb.aes_cca.b1;
                iauth_len = 10;
        }

        /* generate B0 */
        rc = generate_b0(iv, assoclen, authsize, nbytes, b0);
        if (rc)
                return rc;

        /* generate B1:
         * add control info for associated data
         * RFC 3610 and NIST Special Publication 800-38C
         */
        if (b1) {
                memset(b1, 0, 16);
                if (assoclen <= 65280) {
                        *(u16 *)b1 = assoclen;
                        scatterwalk_map_and_copy(b1 + 2, req->src, 0,
                                         iauth_len, SCATTERWALK_FROM_SG);
                } else {
                        *(u16 *)b1 = (u16)(0xfffe);
                        *(u32 *)&b1[2] = assoclen;
                        scatterwalk_map_and_copy(b1 + 6, req->src, 0,
                                         iauth_len, SCATTERWALK_FROM_SG);
                }
        }

        /* now copy any remaining AAD to scatterlist and call nx... */
        if (!assoclen) {
                return rc;
        } else if (assoclen <= 14) {
                unsigned int len = 16;

                nx_insg = nx_build_sg_list(nx_insg, b1, &len, nx_ctx->ap->sglen);

                if (len != 16)
                        return -EINVAL;

                nx_outsg = nx_build_sg_list(nx_outsg, tmp, &len,
                                            nx_ctx->ap->sglen);

                if (len != 16)
                        return -EINVAL;

                /* inlen should be negative, indicating to phyp that its a
                 * pointer to an sg list */
                nx_ctx->op.inlen = (nx_ctx->in_sg - nx_insg) *
                                        sizeof(struct nx_sg);
                nx_ctx->op.outlen = (nx_ctx->out_sg - nx_outsg) *
                                        sizeof(struct nx_sg);

                NX_CPB_FDM(nx_ctx->csbcpb) |= NX_FDM_ENDE_ENCRYPT;
                NX_CPB_FDM(nx_ctx->csbcpb) |= NX_FDM_INTERMEDIATE;

                result = nx_ctx->csbcpb->cpb.aes_ccm.out_pat_or_mac;

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

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

        } else {
                unsigned int processed = 0, to_process;

                processed += iauth_len;

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

                do {
                        to_process = min_t(u32, assoclen - processed,
                                           nx_ctx->ap->databytelen);

                        nx_insg = nx_walk_and_build(nx_ctx->in_sg,
                                                    nx_ctx->ap->sglen,
                                                    req->src, processed,
                                                    &to_process);

                        if ((to_process + processed) < assoclen) {
                                NX_CPB_FDM(nx_ctx->csbcpb_aead) |=
                                        NX_FDM_INTERMEDIATE;
                        } else {
                                NX_CPB_FDM(nx_ctx->csbcpb_aead) &=
                                        ~NX_FDM_INTERMEDIATE;
                        }


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

                        result = nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0;

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

                        memcpy(nx_ctx->csbcpb_aead->cpb.aes_cca.b0,
                                nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0,
                                AES_BLOCK_SIZE);

                        NX_CPB_FDM(nx_ctx->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 < assoclen);

                result = nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0;
        }

        memcpy(out, result, AES_BLOCK_SIZE);

        return rc;
}

static int ccm_nx_decrypt(struct aead_request   *req,
                          struct blkcipher_desc *desc,
                          unsigned int assoclen)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        unsigned int nbytes = req->cryptlen;
        unsigned int authsize = crypto_aead_authsize(crypto_aead_reqtfm(req));
        struct nx_ccm_priv *priv = &nx_ctx->priv.ccm;
        unsigned long irq_flags;
        unsigned int processed = 0, to_process;
        int rc = -1;

        spin_lock_irqsave(&nx_ctx->lock, irq_flags);

        nbytes -= authsize;

        /* copy out the auth tag to compare with later */
        scatterwalk_map_and_copy(priv->oauth_tag,
                                 req->src, nbytes + req->assoclen, authsize,
                                 SCATTERWALK_FROM_SG);

        rc = generate_pat(desc->info, req, nx_ctx, authsize, nbytes, assoclen,
                          csbcpb->cpb.aes_ccm.in_pat_or_b0);
        if (rc)
                goto out;

        do {

                /* to_process: the AES_BLOCK_SIZE data chunk to process in this
                 * update. This value is bound by sg list limits.
                 */
                to_process = nbytes - processed;

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

                NX_CPB_FDM(nx_ctx->csbcpb) &= ~NX_FDM_ENDE_ENCRYPT;

                rc = nx_build_sg_lists(nx_ctx, desc, req->dst, req->src,
                                       &to_process, processed + req->assoclen,
                                       csbcpb->cpb.aes_ccm.iv_or_ctr);
                if (rc)
                        goto out;

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

                /* for partial completion, copy following for next
                 * entry into loop...
                 */
                memcpy(desc->info, csbcpb->cpb.aes_ccm.out_ctr, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_ccm.in_pat_or_b0,
                        csbcpb->cpb.aes_ccm.out_pat_or_mac, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_ccm.in_s0,
                        csbcpb->cpb.aes_ccm.out_s0, AES_BLOCK_SIZE);

                NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;

                /* update stats */
                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);

        rc = crypto_memneq(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,
                    authsize) ? -EBADMSG : 0;
out:
        spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
        return rc;
}

static int ccm_nx_encrypt(struct aead_request   *req,
                          struct blkcipher_desc *desc,
                          unsigned int assoclen)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
        struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
        unsigned int nbytes = req->cryptlen;
        unsigned int authsize = crypto_aead_authsize(crypto_aead_reqtfm(req));
        unsigned long irq_flags;
        unsigned int processed = 0, to_process;
        int rc = -1;

        spin_lock_irqsave(&nx_ctx->lock, irq_flags);

        rc = generate_pat(desc->info, req, nx_ctx, authsize, nbytes, assoclen,
                          csbcpb->cpb.aes_ccm.in_pat_or_b0);
        if (rc)
                goto out;

        do {
                /* to process: the AES_BLOCK_SIZE data chunk to process in this
                 * update. This value is bound by sg list limits.
                 */
                to_process = nbytes - processed;

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

                NX_CPB_FDM(csbcpb) |= NX_FDM_ENDE_ENCRYPT;

                rc = nx_build_sg_lists(nx_ctx, desc, req->dst, req->src,
                                       &to_process, processed + req->assoclen,
                                       csbcpb->cpb.aes_ccm.iv_or_ctr);
                if (rc)
                        goto out;

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

                /* for partial completion, copy following for next
                 * entry into loop...
                 */
                memcpy(desc->info, csbcpb->cpb.aes_ccm.out_ctr, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_ccm.in_pat_or_b0,
                        csbcpb->cpb.aes_ccm.out_pat_or_mac, AES_BLOCK_SIZE);
                memcpy(csbcpb->cpb.aes_ccm.in_s0,
                        csbcpb->cpb.aes_ccm.out_s0, AES_BLOCK_SIZE);

                NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;

                /* update stats */
                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);

        /* copy out the auth tag */
        scatterwalk_map_and_copy(csbcpb->cpb.aes_ccm.out_pat_or_mac,
                                 req->dst, nbytes + req->assoclen, authsize,
                                 SCATTERWALK_TO_SG);

out:
        spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
        return rc;
}

static int ccm4309_aes_nx_encrypt(struct aead_request *req)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        struct blkcipher_desc desc;
        u8 *iv = rctx->iv;

        iv[0] = 3;
        memcpy(iv + 1, nx_ctx->priv.ccm.nonce, 3);
        memcpy(iv + 4, req->iv, 8);

        desc.info = iv;

        return ccm_nx_encrypt(req, &desc, req->assoclen - 8);
}

static int ccm_aes_nx_encrypt(struct aead_request *req)
{
        struct blkcipher_desc desc;
        int rc;

        desc.info = req->iv;

        rc = crypto_ccm_check_iv(desc.info);
        if (rc)
                return rc;

        return ccm_nx_encrypt(req, &desc, req->assoclen);
}

static int ccm4309_aes_nx_decrypt(struct aead_request *req)
{
        struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
        struct nx_gcm_rctx *rctx = aead_request_ctx(req);
        struct blkcipher_desc desc;
        u8 *iv = rctx->iv;

        iv[0] = 3;
        memcpy(iv + 1, nx_ctx->priv.ccm.nonce, 3);
        memcpy(iv + 4, req->iv, 8);

        desc.info = iv;

        return ccm_nx_decrypt(req, &desc, req->assoclen - 8);
}

static int ccm_aes_nx_decrypt(struct aead_request *req)
{
        struct blkcipher_desc desc;
        int rc;

        desc.info = req->iv;

        rc = crypto_ccm_check_iv(desc.info);
        if (rc)
                return rc;

        return ccm_nx_decrypt(req, &desc, req->assoclen);
}

/* 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_ccm_aes_alg = {
        .base = {
                .cra_name        = "ccm(aes)",
                .cra_driver_name = "ccm-aes-nx",
                .cra_priority    = 300,
                .cra_flags       = CRYPTO_ALG_NEED_FALLBACK,
                .cra_blocksize   = 1,
                .cra_ctxsize     = sizeof(struct nx_crypto_ctx),
                .cra_module      = THIS_MODULE,
        },
        .init        = nx_crypto_ctx_aes_ccm_init,
        .exit        = nx_crypto_ctx_aead_exit,
        .ivsize      = AES_BLOCK_SIZE,
        .maxauthsize = AES_BLOCK_SIZE,
        .setkey      = ccm_aes_nx_set_key,
        .setauthsize = ccm_aes_nx_setauthsize,
        .encrypt     = ccm_aes_nx_encrypt,
        .decrypt     = ccm_aes_nx_decrypt,
};

struct aead_alg nx_ccm4309_aes_alg = {
        .base = {
                .cra_name        = "rfc4309(ccm(aes))",
                .cra_driver_name = "rfc4309-ccm-aes-nx",
                .cra_priority    = 300,
                .cra_flags       = CRYPTO_ALG_NEED_FALLBACK,
                .cra_blocksize   = 1,
                .cra_ctxsize     = sizeof(struct nx_crypto_ctx),
                .cra_module      = THIS_MODULE,
        },
        .init        = nx_crypto_ctx_aes_ccm_init,
        .exit        = nx_crypto_ctx_aead_exit,
        .ivsize      = 8,
        .maxauthsize = AES_BLOCK_SIZE,
        .setkey      = ccm4309_aes_nx_set_key,
        .setauthsize = ccm4309_aes_nx_setauthsize,
        .encrypt     = ccm4309_aes_nx_encrypt,
        .decrypt     = ccm4309_aes_nx_decrypt,
};