// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD Cryptographic Coprocessor (CCP) AES GCM crypto API support
 *
 * Copyright (C) 2016,2017 Advanced Micro Devices, Inc.
 *
 * Author: Gary R Hook <gary.hook@amd.com>
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <crypto/internal/aead.h>
#include <crypto/algapi.h>
#include <crypto/aes.h>
#include <crypto/ctr.h>
#include <crypto/gcm.h>
#include <crypto/scatterwalk.h>

#include "ccp-crypto.h"

static int ccp_aes_gcm_complete(struct crypto_async_request *async_req, int ret)
{
        return ret;
}

static int ccp_aes_gcm_setkey(struct crypto_aead *tfm, const u8 *key,
                              unsigned int key_len)
{
        struct ccp_ctx *ctx = crypto_aead_ctx(tfm);

        switch (key_len) {
        case AES_KEYSIZE_128:
                ctx->u.aes.type = CCP_AES_TYPE_128;
                break;
        case AES_KEYSIZE_192:
                ctx->u.aes.type = CCP_AES_TYPE_192;
                break;
        case AES_KEYSIZE_256:
                ctx->u.aes.type = CCP_AES_TYPE_256;
                break;
        default:
                return -EINVAL;
        }

        ctx->u.aes.mode = CCP_AES_MODE_GCM;
        ctx->u.aes.key_len = key_len;

        memcpy(ctx->u.aes.key, key, key_len);
        sg_init_one(&ctx->u.aes.key_sg, ctx->u.aes.key, key_len);

        return 0;
}

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

        return 0;
}

static int ccp_aes_gcm_crypt(struct aead_request *req, bool encrypt)
{
        struct crypto_aead *tfm = crypto_aead_reqtfm(req);
        struct ccp_ctx *ctx = crypto_aead_ctx(tfm);
        struct ccp_aes_req_ctx *rctx = aead_request_ctx(req);
        struct scatterlist *iv_sg = NULL;
        unsigned int iv_len = 0;
        int i;
        int ret = 0;

        if (!ctx->u.aes.key_len)
                return -EINVAL;

        if (ctx->u.aes.mode != CCP_AES_MODE_GCM)
                return -EINVAL;

        if (!req->iv)
                return -EINVAL;

        /*
         * 5 parts:
         *   plaintext/ciphertext input
         *   AAD
         *   key
         *   IV
         *   Destination+tag buffer
         */

        /* Prepare the IV: 12 bytes + an integer (counter) */
        memcpy(rctx->iv, req->iv, GCM_AES_IV_SIZE);
        for (i = 0; i < 3; i++)
                rctx->iv[i + GCM_AES_IV_SIZE] = 0;
        rctx->iv[AES_BLOCK_SIZE - 1] = 1;

        /* Set up a scatterlist for the IV */
        iv_sg = &rctx->iv_sg;
        iv_len = AES_BLOCK_SIZE;
        sg_init_one(iv_sg, rctx->iv, iv_len);

        /* The AAD + plaintext are concatenated in the src buffer */
        memset(&rctx->cmd, 0, sizeof(rctx->cmd));
        INIT_LIST_HEAD(&rctx->cmd.entry);
        rctx->cmd.engine = CCP_ENGINE_AES;
        rctx->cmd.u.aes.authsize = crypto_aead_authsize(tfm);
        rctx->cmd.u.aes.type = ctx->u.aes.type;
        rctx->cmd.u.aes.mode = ctx->u.aes.mode;
        rctx->cmd.u.aes.action = encrypt;
        rctx->cmd.u.aes.key = &ctx->u.aes.key_sg;
        rctx->cmd.u.aes.key_len = ctx->u.aes.key_len;
        rctx->cmd.u.aes.iv = iv_sg;
        rctx->cmd.u.aes.iv_len = iv_len;
        rctx->cmd.u.aes.src = req->src;
        rctx->cmd.u.aes.src_len = req->cryptlen;
        rctx->cmd.u.aes.aad_len = req->assoclen;

        /* The cipher text + the tag are in the dst buffer */
        rctx->cmd.u.aes.dst = req->dst;

        ret = ccp_crypto_enqueue_request(&req->base, &rctx->cmd);

        return ret;
}

static int ccp_aes_gcm_encrypt(struct aead_request *req)
{
        return ccp_aes_gcm_crypt(req, CCP_AES_ACTION_ENCRYPT);
}

static int ccp_aes_gcm_decrypt(struct aead_request *req)
{
        return ccp_aes_gcm_crypt(req, CCP_AES_ACTION_DECRYPT);
}

static int ccp_aes_gcm_cra_init(struct crypto_aead *tfm)
{
        struct ccp_ctx *ctx = crypto_aead_ctx(tfm);

        ctx->complete = ccp_aes_gcm_complete;
        ctx->u.aes.key_len = 0;

        crypto_aead_set_reqsize(tfm, sizeof(struct ccp_aes_req_ctx));

        return 0;
}

static void ccp_aes_gcm_cra_exit(struct crypto_tfm *tfm)
{
}

static struct aead_alg ccp_aes_gcm_defaults = {
        .setkey = ccp_aes_gcm_setkey,
        .setauthsize = ccp_aes_gcm_setauthsize,
        .encrypt = ccp_aes_gcm_encrypt,
        .decrypt = ccp_aes_gcm_decrypt,
        .init = ccp_aes_gcm_cra_init,
        .ivsize = GCM_AES_IV_SIZE,
        .maxauthsize = AES_BLOCK_SIZE,
        .base = {
                .cra_flags      = CRYPTO_ALG_ASYNC |
                                  CRYPTO_ALG_ALLOCATES_MEMORY |
                                  CRYPTO_ALG_KERN_DRIVER_ONLY |
                                  CRYPTO_ALG_NEED_FALLBACK,
                .cra_blocksize  = AES_BLOCK_SIZE,
                .cra_ctxsize    = sizeof(struct ccp_ctx),
                .cra_priority   = CCP_CRA_PRIORITY,
                .cra_exit       = ccp_aes_gcm_cra_exit,
                .cra_module     = THIS_MODULE,
        },
};

struct ccp_aes_aead_def {
        enum ccp_aes_mode mode;
        unsigned int version;
        const char *name;
        const char *driver_name;
        unsigned int blocksize;
        unsigned int ivsize;
        struct aead_alg *alg_defaults;
};

static struct ccp_aes_aead_def aes_aead_algs[] = {
        {
                .mode           = CCP_AES_MODE_GHASH,
                .version        = CCP_VERSION(5, 0),
                .name           = "gcm(aes)",
                .driver_name    = "gcm-aes-ccp",
                .blocksize      = 1,
                .ivsize         = AES_BLOCK_SIZE,
                .alg_defaults   = &ccp_aes_gcm_defaults,
        },
};

static int ccp_register_aes_aead(struct list_head *head,
                                 const struct ccp_aes_aead_def *def)
{
        struct ccp_crypto_aead *ccp_aead;
        struct aead_alg *alg;
        int ret;

        ccp_aead = kzalloc(sizeof(*ccp_aead), GFP_KERNEL);
        if (!ccp_aead)
                return -ENOMEM;

        INIT_LIST_HEAD(&ccp_aead->entry);

        ccp_aead->mode = def->mode;

        /* Copy the defaults and override as necessary */
        alg = &ccp_aead->alg;
        *alg = *def->alg_defaults;
        snprintf(alg->base.cra_name, CRYPTO_MAX_ALG_NAME, "%s", def->name);
        snprintf(alg->base.cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s",
                 def->driver_name);
        alg->base.cra_blocksize = def->blocksize;

        ret = crypto_register_aead(alg);
        if (ret) {
                pr_err("%s aead algorithm registration error (%d)\n",
                       alg->base.cra_name, ret);
                kfree(ccp_aead);
                return ret;
        }

        list_add(&ccp_aead->entry, head);

        return 0;
}

int ccp_register_aes_aeads(struct list_head *head)
{
        int i, ret;
        unsigned int ccpversion = ccp_version();

        for (i = 0; i < ARRAY_SIZE(aes_aead_algs); i++) {
                if (aes_aead_algs[i].version > ccpversion)
                        continue;
                ret = ccp_register_aes_aead(head, &aes_aead_algs[i]);
                if (ret)
                        return ret;
        }

        return 0;
}