/*
 *  zcrypt 2.1.0
 *
 *  Copyright IBM Corp. 2001, 2012
 *  Author(s): Robert Burroughs
 *             Eric Rossman (edrossma@us.ibm.com)
 *
 *  Hotplug & misc device support: Jochen Roehrig (roehrig@de.ibm.com)
 *  Major cleanup & driver split: Martin Schwidefsky <schwidefsky@de.ibm.com>
 *                                Ralph Wuerthner <rwuerthn@de.ibm.com>
 *  MSGTYPE restruct:             Holger Dengler <hd@linux.vnet.ibm.com>
 *
 * 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, or (at your option)
 * any later version.
 *
 * 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.
 */

#define KMSG_COMPONENT "zcrypt"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/atomic.h>
#include <linux/uaccess.h>

#include "ap_bus.h"
#include "zcrypt_api.h"
#include "zcrypt_error.h"
#include "zcrypt_msgtype50.h"

#define CEX3A_MAX_MOD_SIZE      512     /* 4096 bits    */

#define CEX2A_MAX_RESPONSE_SIZE 0x110   /* max outputdatalength + type80_hdr */

#define CEX3A_MAX_RESPONSE_SIZE 0x210   /* 512 bit modulus
                                         * (max outputdatalength) +
                                         * type80_hdr*/

MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("Cryptographic Accelerator (message type 50), " \
                   "Copyright IBM Corp. 2001, 2012");
MODULE_LICENSE("GPL");

static void zcrypt_cex2a_receive(struct ap_device *, struct ap_message *,
                                 struct ap_message *);

/**
 * The type 50 message family is associated with a CEX2A card.
 *
 * The four members of the family are described below.
 *
 * Note that all unsigned char arrays are right-justified and left-padded
 * with zeroes.
 *
 * Note that all reserved fields must be zeroes.
 */
struct type50_hdr {
        unsigned char   reserved1;
        unsigned char   msg_type_code;  /* 0x50 */
        unsigned short  msg_len;
        unsigned char   reserved2;
        unsigned char   ignored;
        unsigned short  reserved3;
} __packed;

#define TYPE50_TYPE_CODE        0x50

#define TYPE50_MEB1_FMT         0x0001
#define TYPE50_MEB2_FMT         0x0002
#define TYPE50_MEB3_FMT         0x0003
#define TYPE50_CRB1_FMT         0x0011
#define TYPE50_CRB2_FMT         0x0012
#define TYPE50_CRB3_FMT         0x0013

/* Mod-Exp, with a small modulus */
struct type50_meb1_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0001 */
        unsigned char   reserved[6];
        unsigned char   exponent[128];
        unsigned char   modulus[128];
        unsigned char   message[128];
} __packed;

/* Mod-Exp, with a large modulus */
struct type50_meb2_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0002 */
        unsigned char   reserved[6];
        unsigned char   exponent[256];
        unsigned char   modulus[256];
        unsigned char   message[256];
} __packed;

/* Mod-Exp, with a larger modulus */
struct type50_meb3_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0003 */
        unsigned char   reserved[6];
        unsigned char   exponent[512];
        unsigned char   modulus[512];
        unsigned char   message[512];
} __packed;

/* CRT, with a small modulus */
struct type50_crb1_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0011 */
        unsigned char   reserved[6];
        unsigned char   p[64];
        unsigned char   q[64];
        unsigned char   dp[64];
        unsigned char   dq[64];
        unsigned char   u[64];
        unsigned char   message[128];
} __packed;

/* CRT, with a large modulus */
struct type50_crb2_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0012 */
        unsigned char   reserved[6];
        unsigned char   p[128];
        unsigned char   q[128];
        unsigned char   dp[128];
        unsigned char   dq[128];
        unsigned char   u[128];
        unsigned char   message[256];
} __packed;

/* CRT, with a larger modulus */
struct type50_crb3_msg {
        struct type50_hdr header;
        unsigned short  keyblock_type;  /* 0x0013 */
        unsigned char   reserved[6];
        unsigned char   p[256];
        unsigned char   q[256];
        unsigned char   dp[256];
        unsigned char   dq[256];
        unsigned char   u[256];
        unsigned char   message[512];
} __packed;

/**
 * The type 80 response family is associated with a CEX2A card.
 *
 * Note that all unsigned char arrays are right-justified and left-padded
 * with zeroes.
 *
 * Note that all reserved fields must be zeroes.
 */

#define TYPE80_RSP_CODE 0x80

struct type80_hdr {
        unsigned char   reserved1;
        unsigned char   type;           /* 0x80 */
        unsigned short  len;
        unsigned char   code;           /* 0x00 */
        unsigned char   reserved2[3];
        unsigned char   reserved3[8];
} __packed;

/**
 * Convert a ICAMEX message to a type50 MEX message.
 *
 * @zdev: crypto device pointer
 * @zreq: crypto request pointer
 * @mex: pointer to user input data
 *
 * Returns 0 on success or -EFAULT.
 */
static int ICAMEX_msg_to_type50MEX_msg(struct zcrypt_device *zdev,
                                       struct ap_message *ap_msg,
                                       struct ica_rsa_modexpo *mex)
{
        unsigned char *mod, *exp, *inp;
        int mod_len;

        mod_len = mex->inputdatalength;

        if (mod_len <= 128) {
                struct type50_meb1_msg *meb1 = ap_msg->message;
                memset(meb1, 0, sizeof(*meb1));
                ap_msg->length = sizeof(*meb1);
                meb1->header.msg_type_code = TYPE50_TYPE_CODE;
                meb1->header.msg_len = sizeof(*meb1);
                meb1->keyblock_type = TYPE50_MEB1_FMT;
                mod = meb1->modulus + sizeof(meb1->modulus) - mod_len;
                exp = meb1->exponent + sizeof(meb1->exponent) - mod_len;
                inp = meb1->message + sizeof(meb1->message) - mod_len;
        } else if (mod_len <= 256) {
                struct type50_meb2_msg *meb2 = ap_msg->message;
                memset(meb2, 0, sizeof(*meb2));
                ap_msg->length = sizeof(*meb2);
                meb2->header.msg_type_code = TYPE50_TYPE_CODE;
                meb2->header.msg_len = sizeof(*meb2);
                meb2->keyblock_type = TYPE50_MEB2_FMT;
                mod = meb2->modulus + sizeof(meb2->modulus) - mod_len;
                exp = meb2->exponent + sizeof(meb2->exponent) - mod_len;
                inp = meb2->message + sizeof(meb2->message) - mod_len;
        } else {
                /* mod_len > 256 = 4096 bit RSA Key */
                struct type50_meb3_msg *meb3 = ap_msg->message;
                memset(meb3, 0, sizeof(*meb3));
                ap_msg->length = sizeof(*meb3);
                meb3->header.msg_type_code = TYPE50_TYPE_CODE;
                meb3->header.msg_len = sizeof(*meb3);
                meb3->keyblock_type = TYPE50_MEB3_FMT;
                mod = meb3->modulus + sizeof(meb3->modulus) - mod_len;
                exp = meb3->exponent + sizeof(meb3->exponent) - mod_len;
                inp = meb3->message + sizeof(meb3->message) - mod_len;
        }

        if (copy_from_user(mod, mex->n_modulus, mod_len) ||
            copy_from_user(exp, mex->b_key, mod_len) ||
            copy_from_user(inp, mex->inputdata, mod_len))
                return -EFAULT;
        return 0;
}

/**
 * Convert a ICACRT message to a type50 CRT message.
 *
 * @zdev: crypto device pointer
 * @zreq: crypto request pointer
 * @crt: pointer to user input data
 *
 * Returns 0 on success or -EFAULT.
 */
static int ICACRT_msg_to_type50CRT_msg(struct zcrypt_device *zdev,
                                       struct ap_message *ap_msg,
                                       struct ica_rsa_modexpo_crt *crt)
{
        int mod_len, short_len;
        unsigned char *p, *q, *dp, *dq, *u, *inp;

        mod_len = crt->inputdatalength;
        short_len = (mod_len + 1) / 2;

        /*
         * CEX2A and CEX3A w/o FW update can handle requests up to
         * 256 byte modulus (2k keys).
         * CEX3A with FW update and CEX4A cards are able to handle
         * 512 byte modulus (4k keys).
         */
        if (mod_len <= 128) {           /* up to 1024 bit key size */
                struct type50_crb1_msg *crb1 = ap_msg->message;
                memset(crb1, 0, sizeof(*crb1));
                ap_msg->length = sizeof(*crb1);
                crb1->header.msg_type_code = TYPE50_TYPE_CODE;
                crb1->header.msg_len = sizeof(*crb1);
                crb1->keyblock_type = TYPE50_CRB1_FMT;
                p = crb1->p + sizeof(crb1->p) - short_len;
                q = crb1->q + sizeof(crb1->q) - short_len;
                dp = crb1->dp + sizeof(crb1->dp) - short_len;
                dq = crb1->dq + sizeof(crb1->dq) - short_len;
                u = crb1->u + sizeof(crb1->u) - short_len;
                inp = crb1->message + sizeof(crb1->message) - mod_len;
        } else if (mod_len <= 256) {    /* up to 2048 bit key size */
                struct type50_crb2_msg *crb2 = ap_msg->message;
                memset(crb2, 0, sizeof(*crb2));
                ap_msg->length = sizeof(*crb2);
                crb2->header.msg_type_code = TYPE50_TYPE_CODE;
                crb2->header.msg_len = sizeof(*crb2);
                crb2->keyblock_type = TYPE50_CRB2_FMT;
                p = crb2->p + sizeof(crb2->p) - short_len;
                q = crb2->q + sizeof(crb2->q) - short_len;
                dp = crb2->dp + sizeof(crb2->dp) - short_len;
                dq = crb2->dq + sizeof(crb2->dq) - short_len;
                u = crb2->u + sizeof(crb2->u) - short_len;
                inp = crb2->message + sizeof(crb2->message) - mod_len;
        } else if ((mod_len <= 512) &&  /* up to 4096 bit key size */
                   (zdev->max_mod_size == CEX3A_MAX_MOD_SIZE)) { /* >= CEX3A */
                struct type50_crb3_msg *crb3 = ap_msg->message;
                memset(crb3, 0, sizeof(*crb3));
                ap_msg->length = sizeof(*crb3);
                crb3->header.msg_type_code = TYPE50_TYPE_CODE;
                crb3->header.msg_len = sizeof(*crb3);
                crb3->keyblock_type = TYPE50_CRB3_FMT;
                p = crb3->p + sizeof(crb3->p) - short_len;
                q = crb3->q + sizeof(crb3->q) - short_len;
                dp = crb3->dp + sizeof(crb3->dp) - short_len;
                dq = crb3->dq + sizeof(crb3->dq) - short_len;
                u = crb3->u + sizeof(crb3->u) - short_len;
                inp = crb3->message + sizeof(crb3->message) - mod_len;
        } else
                return -EINVAL;

        /*
         * correct the offset of p, bp and mult_inv according zcrypt.h
         * block size right aligned (skip the first byte)
         */
        if (copy_from_user(p, crt->np_prime + MSGTYPE_ADJUSTMENT, short_len) ||
            copy_from_user(q, crt->nq_prime, short_len) ||
            copy_from_user(dp, crt->bp_key + MSGTYPE_ADJUSTMENT, short_len) ||
            copy_from_user(dq, crt->bq_key, short_len) ||
            copy_from_user(u, crt->u_mult_inv + MSGTYPE_ADJUSTMENT, short_len) ||
            copy_from_user(inp, crt->inputdata, mod_len))
                return -EFAULT;

        return 0;
}

/**
 * Copy results from a type 80 reply message back to user space.
 *
 * @zdev: crypto device pointer
 * @reply: reply AP message.
 * @data: pointer to user output data
 * @length: size of user output data
 *
 * Returns 0 on success or -EFAULT.
 */
static int convert_type80(struct zcrypt_device *zdev,
                          struct ap_message *reply,
                          char __user *outputdata,
                          unsigned int outputdatalength)
{
        struct type80_hdr *t80h = reply->message;
        unsigned char *data;

        if (t80h->len < sizeof(*t80h) + outputdatalength) {
                /* The result is too short, the CEX2A card may not do that.. */
                zdev->online = 0;
                pr_err("Cryptographic device %x failed and was set offline\n",
                       AP_QID_DEVICE(zdev->ap_dev->qid));
                ZCRYPT_DBF_DEV(DBF_ERR, zdev, "dev%04xo%drc%d",
                               AP_QID_DEVICE(zdev->ap_dev->qid),
                               zdev->online, t80h->code);

                return -EAGAIN; /* repeat the request on a different device. */
        }
        if (zdev->user_space_type == ZCRYPT_CEX2A)
                BUG_ON(t80h->len > CEX2A_MAX_RESPONSE_SIZE);
        else
                BUG_ON(t80h->len > CEX3A_MAX_RESPONSE_SIZE);
        data = reply->message + t80h->len - outputdatalength;
        if (copy_to_user(outputdata, data, outputdatalength))
                return -EFAULT;
        return 0;
}

static int convert_response(struct zcrypt_device *zdev,
                            struct ap_message *reply,
                            char __user *outputdata,
                            unsigned int outputdatalength)
{
        /* Response type byte is the second byte in the response. */
        switch (((unsigned char *) reply->message)[1]) {
        case TYPE82_RSP_CODE:
        case TYPE88_RSP_CODE:
                return convert_error(zdev, reply);
        case TYPE80_RSP_CODE:
                return convert_type80(zdev, reply,
                                      outputdata, outputdatalength);
        default: /* Unknown response type, this should NEVER EVER happen */
                zdev->online = 0;
                pr_err("Cryptographic device %x failed and was set offline\n",
                       AP_QID_DEVICE(zdev->ap_dev->qid));
                ZCRYPT_DBF_DEV(DBF_ERR, zdev, "dev%04xo%dfail",
                               AP_QID_DEVICE(zdev->ap_dev->qid), zdev->online);
                return -EAGAIN; /* repeat the request on a different device. */
        }
}

/**
 * This function is called from the AP bus code after a crypto request
 * "msg" has finished with the reply message "reply".
 * It is called from tasklet context.
 * @ap_dev: pointer to the AP device
 * @msg: pointer to the AP message
 * @reply: pointer to the AP reply message
 */
static void zcrypt_cex2a_receive(struct ap_device *ap_dev,
                                 struct ap_message *msg,
                                 struct ap_message *reply)
{
        static struct error_hdr error_reply = {
                .type = TYPE82_RSP_CODE,
                .reply_code = REP82_ERROR_MACHINE_FAILURE,
        };
        struct type80_hdr *t80h;
        int length;

        /* Copy the reply message to the request message buffer. */
        if (!reply)
                goto out;       /* ap_msg->rc indicates the error */
        t80h = reply->message;
        if (t80h->type == TYPE80_RSP_CODE) {
                if (ap_dev->device_type == AP_DEVICE_TYPE_CEX2A)
                        length = min_t(int,
                                       CEX2A_MAX_RESPONSE_SIZE, t80h->len);
                else
                        length = min_t(int,
                                       CEX3A_MAX_RESPONSE_SIZE, t80h->len);
                memcpy(msg->message, reply->message, length);
        } else
                memcpy(msg->message, reply->message, sizeof(error_reply));
out:
        complete((struct completion *) msg->private);
}

static atomic_t zcrypt_step = ATOMIC_INIT(0);

/**
 * The request distributor calls this function if it picked the CEX2A
 * device to handle a modexpo request.
 * @zdev: pointer to zcrypt_device structure that identifies the
 *        CEX2A device to the request distributor
 * @mex: pointer to the modexpo request buffer
 */
static long zcrypt_cex2a_modexpo(struct zcrypt_device *zdev,
                                 struct ica_rsa_modexpo *mex)
{
        struct ap_message ap_msg;
        struct completion work;
        int rc;

        ap_init_message(&ap_msg);
        if (zdev->user_space_type == ZCRYPT_CEX2A)
                ap_msg.message = kmalloc(MSGTYPE50_CRB2_MAX_MSG_SIZE,
                                         GFP_KERNEL);
        else
                ap_msg.message = kmalloc(MSGTYPE50_CRB3_MAX_MSG_SIZE,
                                         GFP_KERNEL);
        if (!ap_msg.message)
                return -ENOMEM;
        ap_msg.receive = zcrypt_cex2a_receive;
        ap_msg.psmid = (((unsigned long long) current->pid) << 32) +
                                atomic_inc_return(&zcrypt_step);
        ap_msg.private = &work;
        rc = ICAMEX_msg_to_type50MEX_msg(zdev, &ap_msg, mex);
        if (rc)
                goto out_free;
        init_completion(&work);
        ap_queue_message(zdev->ap_dev, &ap_msg);
        rc = wait_for_completion_interruptible(&work);
        if (rc == 0) {
                rc = ap_msg.rc;
                if (rc == 0)
                        rc = convert_response(zdev, &ap_msg, mex->outputdata,
                                              mex->outputdatalength);
        } else
                /* Signal pending. */
                ap_cancel_message(zdev->ap_dev, &ap_msg);
out_free:
        kfree(ap_msg.message);
        return rc;
}

/**
 * The request distributor calls this function if it picked the CEX2A
 * device to handle a modexpo_crt request.
 * @zdev: pointer to zcrypt_device structure that identifies the
 *        CEX2A device to the request distributor
 * @crt: pointer to the modexpoc_crt request buffer
 */
static long zcrypt_cex2a_modexpo_crt(struct zcrypt_device *zdev,
                                     struct ica_rsa_modexpo_crt *crt)
{
        struct ap_message ap_msg;
        struct completion work;
        int rc;

        ap_init_message(&ap_msg);
        if (zdev->user_space_type == ZCRYPT_CEX2A)
                ap_msg.message = kmalloc(MSGTYPE50_CRB2_MAX_MSG_SIZE,
                                         GFP_KERNEL);
        else
                ap_msg.message = kmalloc(MSGTYPE50_CRB3_MAX_MSG_SIZE,
                                         GFP_KERNEL);
        if (!ap_msg.message)
                return -ENOMEM;
        ap_msg.receive = zcrypt_cex2a_receive;
        ap_msg.psmid = (((unsigned long long) current->pid) << 32) +
                                atomic_inc_return(&zcrypt_step);
        ap_msg.private = &work;
        rc = ICACRT_msg_to_type50CRT_msg(zdev, &ap_msg, crt);
        if (rc)
                goto out_free;
        init_completion(&work);
        ap_queue_message(zdev->ap_dev, &ap_msg);
        rc = wait_for_completion_interruptible(&work);
        if (rc == 0) {
                rc = ap_msg.rc;
                if (rc == 0)
                        rc = convert_response(zdev, &ap_msg, crt->outputdata,
                                              crt->outputdatalength);
        } else
                /* Signal pending. */
                ap_cancel_message(zdev->ap_dev, &ap_msg);
out_free:
        kfree(ap_msg.message);
        return rc;
}

/**
 * The crypto operations for message type 50.
 */
static struct zcrypt_ops zcrypt_msgtype50_ops = {
        .rsa_modexpo = zcrypt_cex2a_modexpo,
        .rsa_modexpo_crt = zcrypt_cex2a_modexpo_crt,
        .owner = THIS_MODULE,
        .name = MSGTYPE50_NAME,
        .variant = MSGTYPE50_VARIANT_DEFAULT,
};

int __init zcrypt_msgtype50_init(void)
{
        zcrypt_msgtype_register(&zcrypt_msgtype50_ops);
        return 0;
}

void __exit zcrypt_msgtype50_exit(void)
{
        zcrypt_msgtype_unregister(&zcrypt_msgtype50_ops);
}

module_init(zcrypt_msgtype50_init);
module_exit(zcrypt_msgtype50_exit);