/*
 * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
 * Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef _TLS_OFFLOAD_H
#define _TLS_OFFLOAD_H

#include <linux/types.h>

#include <uapi/linux/tls.h>


/* Maximum data size carried in a TLS record */
#define TLS_MAX_PAYLOAD_SIZE            ((size_t)1 << 14)

#define TLS_HEADER_SIZE                 5
#define TLS_NONCE_OFFSET                TLS_HEADER_SIZE

#define TLS_CRYPTO_INFO_READY(info)     ((info)->cipher_type)

#define TLS_RECORD_TYPE_DATA            0x17

#define TLS_AAD_SPACE_SIZE              13

struct tls_sw_context {
        struct crypto_aead *aead_send;

        /* Sending context */
        char aad_space[TLS_AAD_SPACE_SIZE];

        unsigned int sg_plaintext_size;
        int sg_plaintext_num_elem;
        struct scatterlist sg_plaintext_data[MAX_SKB_FRAGS];

        unsigned int sg_encrypted_size;
        int sg_encrypted_num_elem;
        struct scatterlist sg_encrypted_data[MAX_SKB_FRAGS];

        /* AAD | sg_plaintext_data | sg_tag */
        struct scatterlist sg_aead_in[2];
        /* AAD | sg_encrypted_data (data contain overhead for hdr&iv&tag) */
        struct scatterlist sg_aead_out[2];
};

enum {
        TLS_PENDING_CLOSED_RECORD
};

struct tls_context {
        union {
                struct tls_crypto_info crypto_send;
                struct tls12_crypto_info_aes_gcm_128 crypto_send_aes_gcm_128;
        };

        void *priv_ctx;

        u16 prepend_size;
        u16 tag_size;
        u16 overhead_size;
        u16 iv_size;
        char *iv;
        u16 rec_seq_size;
        char *rec_seq;

        struct scatterlist *partially_sent_record;
        u16 partially_sent_offset;
        unsigned long flags;

        u16 pending_open_record_frags;
        int (*push_pending_record)(struct sock *sk, int flags);
        void (*free_resources)(struct sock *sk);

        void (*sk_write_space)(struct sock *sk);
        void (*sk_proto_close)(struct sock *sk, long timeout);

        int  (*setsockopt)(struct sock *sk, int level,
                           int optname, char __user *optval,
                           unsigned int optlen);
        int  (*getsockopt)(struct sock *sk, int level,
                           int optname, char __user *optval,
                           int __user *optlen);
};

int wait_on_pending_writer(struct sock *sk, long *timeo);
int tls_sk_query(struct sock *sk, int optname, char __user *optval,
                int __user *optlen);
int tls_sk_attach(struct sock *sk, int optname, char __user *optval,
                  unsigned int optlen);


int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx);
int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
int tls_sw_sendpage(struct sock *sk, struct page *page,
                    int offset, size_t size, int flags);
void tls_sw_close(struct sock *sk, long timeout);

void tls_sk_destruct(struct sock *sk, struct tls_context *ctx);
void tls_icsk_clean_acked(struct sock *sk);

int tls_push_sg(struct sock *sk, struct tls_context *ctx,
                struct scatterlist *sg, u16 first_offset,
                int flags);
int tls_push_pending_closed_record(struct sock *sk, struct tls_context *ctx,
                                   int flags, long *timeo);

static inline bool tls_is_pending_closed_record(struct tls_context *ctx)
{
        return test_bit(TLS_PENDING_CLOSED_RECORD, &ctx->flags);
}

static inline int tls_complete_pending_work(struct sock *sk,
                                            struct tls_context *ctx,
                                            int flags, long *timeo)
{
        int rc = 0;

        if (unlikely(sk->sk_write_pending))
                rc = wait_on_pending_writer(sk, timeo);

        if (!rc && tls_is_pending_closed_record(ctx))
                rc = tls_push_pending_closed_record(sk, ctx, flags, timeo);

        return rc;
}

static inline bool tls_is_partially_sent_record(struct tls_context *ctx)
{
        return !!ctx->partially_sent_record;
}

static inline bool tls_is_pending_open_record(struct tls_context *tls_ctx)
{
        return tls_ctx->pending_open_record_frags;
}

static inline void tls_err_abort(struct sock *sk)
{
        sk->sk_err = -EBADMSG;
        sk->sk_error_report(sk);
}

static inline bool tls_bigint_increment(unsigned char *seq, int len)
{
        int i;

        for (i = len - 1; i >= 0; i--) {
                ++seq[i];
                if (seq[i] != 0)
                        break;
        }

        return (i == -1);
}

static inline void tls_advance_record_sn(struct sock *sk,
                                         struct tls_context *ctx)
{
        if (tls_bigint_increment(ctx->rec_seq, ctx->rec_seq_size))
                tls_err_abort(sk);
        tls_bigint_increment(ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
                             ctx->iv_size);
}

static inline void tls_fill_prepend(struct tls_context *ctx,
                             char *buf,
                             size_t plaintext_len,
                             unsigned char record_type)
{
        size_t pkt_len, iv_size = ctx->iv_size;

        pkt_len = plaintext_len + iv_size + ctx->tag_size;

        /* we cover nonce explicit here as well, so buf should be of
         * size KTLS_DTLS_HEADER_SIZE + KTLS_DTLS_NONCE_EXPLICIT_SIZE
         */
        buf[0] = record_type;
        buf[1] = TLS_VERSION_MINOR(ctx->crypto_send.version);
        buf[2] = TLS_VERSION_MAJOR(ctx->crypto_send.version);
        /* we can use IV for nonce explicit according to spec */
        buf[3] = pkt_len >> 8;
        buf[4] = pkt_len & 0xFF;
        memcpy(buf + TLS_NONCE_OFFSET,
               ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv_size);
}

static inline struct tls_context *tls_get_ctx(const struct sock *sk)
{
        struct inet_connection_sock *icsk = inet_csk(sk);

        return icsk->icsk_ulp_data;
}

static inline struct tls_sw_context *tls_sw_ctx(
                const struct tls_context *tls_ctx)
{
        return (struct tls_sw_context *)tls_ctx->priv_ctx;
}

static inline struct tls_offload_context *tls_offload_ctx(
                const struct tls_context *tls_ctx)
{
        return (struct tls_offload_context *)tls_ctx->priv_ctx;
}

int tls_proccess_cmsg(struct sock *sk, struct msghdr *msg,
                      unsigned char *record_type);

#endif /* _TLS_OFFLOAD_H */