/* Copyright (c) 2018, Mellanox Technologies 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.
 */

#include <crypto/aead.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <net/dst.h>
#include <net/inet_connection_sock.h>
#include <net/tcp.h>
#include <net/tls.h>

/* device_offload_lock is used to synchronize tls_dev_add
 * against NETDEV_DOWN notifications.
 */
static DECLARE_RWSEM(device_offload_lock);

static void tls_device_gc_task(struct work_struct *work);

static DECLARE_WORK(tls_device_gc_work, tls_device_gc_task);
static LIST_HEAD(tls_device_gc_list);
static LIST_HEAD(tls_device_list);
static DEFINE_SPINLOCK(tls_device_lock);

static void tls_device_free_ctx(struct tls_context *ctx)
{
        if (ctx->tx_conf == TLS_HW) {
                kfree(tls_offload_ctx_tx(ctx));
                kfree(ctx->tx.rec_seq);
                kfree(ctx->tx.iv);
        }

        if (ctx->rx_conf == TLS_HW)
                kfree(tls_offload_ctx_rx(ctx));

        tls_ctx_free(ctx);
}

static void tls_device_gc_task(struct work_struct *work)
{
        struct tls_context *ctx, *tmp;
        unsigned long flags;
        LIST_HEAD(gc_list);

        spin_lock_irqsave(&tls_device_lock, flags);
        list_splice_init(&tls_device_gc_list, &gc_list);
        spin_unlock_irqrestore(&tls_device_lock, flags);

        list_for_each_entry_safe(ctx, tmp, &gc_list, list) {
                struct net_device *netdev = ctx->netdev;

                if (netdev && ctx->tx_conf == TLS_HW) {
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_TX);
                        dev_put(netdev);
                        ctx->netdev = NULL;
                }

                list_del(&ctx->list);
                tls_device_free_ctx(ctx);
        }
}

static void tls_device_queue_ctx_destruction(struct tls_context *ctx)
{
        unsigned long flags;

        spin_lock_irqsave(&tls_device_lock, flags);
        list_move_tail(&ctx->list, &tls_device_gc_list);

        /* schedule_work inside the spinlock
         * to make sure tls_device_down waits for that work.
         */
        schedule_work(&tls_device_gc_work);

        spin_unlock_irqrestore(&tls_device_lock, flags);
}

/* We assume that the socket is already connected */
static struct net_device *get_netdev_for_sock(struct sock *sk)
{
        struct dst_entry *dst = sk_dst_get(sk);
        struct net_device *netdev = NULL;

        if (likely(dst)) {
                netdev = dst->dev;
                dev_hold(netdev);
        }

        dst_release(dst);

        return netdev;
}

static void destroy_record(struct tls_record_info *record)
{
        int nr_frags = record->num_frags;
        skb_frag_t *frag;

        while (nr_frags-- > 0) {
                frag = &record->frags[nr_frags];
                __skb_frag_unref(frag);
        }
        kfree(record);
}

static void delete_all_records(struct tls_offload_context_tx *offload_ctx)
{
        struct tls_record_info *info, *temp;

        list_for_each_entry_safe(info, temp, &offload_ctx->records_list, list) {
                list_del(&info->list);
                destroy_record(info);
        }

        offload_ctx->retransmit_hint = NULL;
}

static void tls_icsk_clean_acked(struct sock *sk, u32 acked_seq)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_record_info *info, *temp;
        struct tls_offload_context_tx *ctx;
        u64 deleted_records = 0;
        unsigned long flags;

        if (!tls_ctx)
                return;

        ctx = tls_offload_ctx_tx(tls_ctx);

        spin_lock_irqsave(&ctx->lock, flags);
        info = ctx->retransmit_hint;
        if (info && !before(acked_seq, info->end_seq)) {
                ctx->retransmit_hint = NULL;
                list_del(&info->list);
                destroy_record(info);
                deleted_records++;
        }

        list_for_each_entry_safe(info, temp, &ctx->records_list, list) {
                if (before(acked_seq, info->end_seq))
                        break;
                list_del(&info->list);

                destroy_record(info);
                deleted_records++;
        }

        ctx->unacked_record_sn += deleted_records;
        spin_unlock_irqrestore(&ctx->lock, flags);
}

/* At this point, there should be no references on this
 * socket and no in-flight SKBs associated with this
 * socket, so it is safe to free all the resources.
 */
static void tls_device_sk_destruct(struct sock *sk)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);

        tls_ctx->sk_destruct(sk);

        if (tls_ctx->tx_conf == TLS_HW) {
                if (ctx->open_record)
                        destroy_record(ctx->open_record);
                delete_all_records(ctx);
                crypto_free_aead(ctx->aead_send);
                clean_acked_data_disable(inet_csk(sk));
        }

        if (refcount_dec_and_test(&tls_ctx->refcount))
                tls_device_queue_ctx_destruction(tls_ctx);
}

void tls_device_free_resources_tx(struct sock *sk)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);

        tls_free_partial_record(sk, tls_ctx);
}

static void tls_device_resync_tx(struct sock *sk, struct tls_context *tls_ctx,
                                 u32 seq)
{
        struct net_device *netdev;
        struct sk_buff *skb;
        int err = 0;
        u8 *rcd_sn;

        skb = tcp_write_queue_tail(sk);
        if (skb)
                TCP_SKB_CB(skb)->eor = 1;

        rcd_sn = tls_ctx->tx.rec_seq;

        down_read(&device_offload_lock);
        netdev = tls_ctx->netdev;
        if (netdev)
                err = netdev->tlsdev_ops->tls_dev_resync(netdev, sk, seq,
                                                         rcd_sn,
                                                         TLS_OFFLOAD_CTX_DIR_TX);
        up_read(&device_offload_lock);
        if (err)
                return;

        clear_bit_unlock(TLS_TX_SYNC_SCHED, &tls_ctx->flags);
}

static void tls_append_frag(struct tls_record_info *record,
                            struct page_frag *pfrag,
                            int size)
{
        skb_frag_t *frag;

        frag = &record->frags[record->num_frags - 1];
        if (frag->page.p == pfrag->page &&
            frag->page_offset + frag->size == pfrag->offset) {
                frag->size += size;
        } else {
                ++frag;
                frag->page.p = pfrag->page;
                frag->page_offset = pfrag->offset;
                frag->size = size;
                ++record->num_frags;
                get_page(pfrag->page);
        }

        pfrag->offset += size;
        record->len += size;
}

static int tls_push_record(struct sock *sk,
                           struct tls_context *ctx,
                           struct tls_offload_context_tx *offload_ctx,
                           struct tls_record_info *record,
                           struct page_frag *pfrag,
                           int flags,
                           unsigned char record_type)
{
        struct tls_prot_info *prot = &ctx->prot_info;
        struct tcp_sock *tp = tcp_sk(sk);
        struct page_frag dummy_tag_frag;
        skb_frag_t *frag;
        int i;

        /* fill prepend */
        frag = &record->frags[0];
        tls_fill_prepend(ctx,
                         skb_frag_address(frag),
                         record->len - prot->prepend_size,
                         record_type,
                         prot->version);

        /* HW doesn't care about the data in the tag, because it fills it. */
        dummy_tag_frag.page = skb_frag_page(frag);
        dummy_tag_frag.offset = 0;

        tls_append_frag(record, &dummy_tag_frag, prot->tag_size);
        record->end_seq = tp->write_seq + record->len;
        spin_lock_irq(&offload_ctx->lock);
        list_add_tail(&record->list, &offload_ctx->records_list);
        spin_unlock_irq(&offload_ctx->lock);
        offload_ctx->open_record = NULL;

        if (test_bit(TLS_TX_SYNC_SCHED, &ctx->flags))
                tls_device_resync_tx(sk, ctx, tp->write_seq);

        tls_advance_record_sn(sk, prot, &ctx->tx);

        for (i = 0; i < record->num_frags; i++) {
                frag = &record->frags[i];
                sg_unmark_end(&offload_ctx->sg_tx_data[i]);
                sg_set_page(&offload_ctx->sg_tx_data[i], skb_frag_page(frag),
                            frag->size, frag->page_offset);
                sk_mem_charge(sk, frag->size);
                get_page(skb_frag_page(frag));
        }
        sg_mark_end(&offload_ctx->sg_tx_data[record->num_frags - 1]);

        /* all ready, send */
        return tls_push_sg(sk, ctx, offload_ctx->sg_tx_data, 0, flags);
}

static int tls_create_new_record(struct tls_offload_context_tx *offload_ctx,
                                 struct page_frag *pfrag,
                                 size_t prepend_size)
{
        struct tls_record_info *record;
        skb_frag_t *frag;

        record = kmalloc(sizeof(*record), GFP_KERNEL);
        if (!record)
                return -ENOMEM;

        frag = &record->frags[0];
        __skb_frag_set_page(frag, pfrag->page);
        frag->page_offset = pfrag->offset;
        skb_frag_size_set(frag, prepend_size);

        get_page(pfrag->page);
        pfrag->offset += prepend_size;

        record->num_frags = 1;
        record->len = prepend_size;
        offload_ctx->open_record = record;
        return 0;
}

static int tls_do_allocation(struct sock *sk,
                             struct tls_offload_context_tx *offload_ctx,
                             struct page_frag *pfrag,
                             size_t prepend_size)
{
        int ret;

        if (!offload_ctx->open_record) {
                if (unlikely(!skb_page_frag_refill(prepend_size, pfrag,
                                                   sk->sk_allocation))) {
                        sk->sk_prot->enter_memory_pressure(sk);
                        sk_stream_moderate_sndbuf(sk);
                        return -ENOMEM;
                }

                ret = tls_create_new_record(offload_ctx, pfrag, prepend_size);
                if (ret)
                        return ret;

                if (pfrag->size > pfrag->offset)
                        return 0;
        }

        if (!sk_page_frag_refill(sk, pfrag))
                return -ENOMEM;

        return 0;
}

static int tls_push_data(struct sock *sk,
                         struct iov_iter *msg_iter,
                         size_t size, int flags,
                         unsigned char record_type)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_prot_info *prot = &tls_ctx->prot_info;
        struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
        int more = flags & (MSG_SENDPAGE_NOTLAST | MSG_MORE);
        struct tls_record_info *record = ctx->open_record;
        int tls_push_record_flags;
        struct page_frag *pfrag;
        size_t orig_size = size;
        u32 max_open_record_len;
        int copy, rc = 0;
        bool done = false;
        long timeo;

        if (flags &
            ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | MSG_SENDPAGE_NOTLAST))
                return -ENOTSUPP;

        if (sk->sk_err)
                return -sk->sk_err;

        flags |= MSG_SENDPAGE_DECRYPTED;
        tls_push_record_flags = flags | MSG_SENDPAGE_NOTLAST;

        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
        if (tls_is_partially_sent_record(tls_ctx)) {
                rc = tls_push_partial_record(sk, tls_ctx, flags);
                if (rc < 0)
                        return rc;
        }

        pfrag = sk_page_frag(sk);

        /* TLS_HEADER_SIZE is not counted as part of the TLS record, and
         * we need to leave room for an authentication tag.
         */
        max_open_record_len = TLS_MAX_PAYLOAD_SIZE +
                              prot->prepend_size;
        do {
                rc = tls_do_allocation(sk, ctx, pfrag,
                                       prot->prepend_size);
                if (rc) {
                        rc = sk_stream_wait_memory(sk, &timeo);
                        if (!rc)
                                continue;

                        record = ctx->open_record;
                        if (!record)
                                break;
handle_error:
                        if (record_type != TLS_RECORD_TYPE_DATA) {
                                /* avoid sending partial
                                 * record with type !=
                                 * application_data
                                 */
                                size = orig_size;
                                destroy_record(record);
                                ctx->open_record = NULL;
                        } else if (record->len > prot->prepend_size) {
                                goto last_record;
                        }

                        break;
                }

                record = ctx->open_record;
                copy = min_t(size_t, size, (pfrag->size - pfrag->offset));
                copy = min_t(size_t, copy, (max_open_record_len - record->len));

                if (copy_from_iter_nocache(page_address(pfrag->page) +
                                               pfrag->offset,
                                           copy, msg_iter) != copy) {
                        rc = -EFAULT;
                        goto handle_error;
                }
                tls_append_frag(record, pfrag, copy);

                size -= copy;
                if (!size) {
last_record:
                        tls_push_record_flags = flags;
                        if (more) {
                                tls_ctx->pending_open_record_frags =
                                                !!record->num_frags;
                                break;
                        }

                        done = true;
                }

                if (done || record->len >= max_open_record_len ||
                    (record->num_frags >= MAX_SKB_FRAGS - 1)) {
                        rc = tls_push_record(sk,
                                             tls_ctx,
                                             ctx,
                                             record,
                                             pfrag,
                                             tls_push_record_flags,
                                             record_type);
                        if (rc < 0)
                                break;
                }
        } while (!done);

        if (orig_size - size > 0)
                rc = orig_size - size;

        return rc;
}

int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
{
        unsigned char record_type = TLS_RECORD_TYPE_DATA;
        int rc;

        lock_sock(sk);

        if (unlikely(msg->msg_controllen)) {
                rc = tls_proccess_cmsg(sk, msg, &record_type);
                if (rc)
                        goto out;
        }

        rc = tls_push_data(sk, &msg->msg_iter, size,
                           msg->msg_flags, record_type);

out:
        release_sock(sk);
        return rc;
}

int tls_device_sendpage(struct sock *sk, struct page *page,
                        int offset, size_t size, int flags)
{
        struct iov_iter msg_iter;
        char *kaddr = kmap(page);
        struct kvec iov;
        int rc;

        if (flags & MSG_SENDPAGE_NOTLAST)
                flags |= MSG_MORE;

        lock_sock(sk);

        if (flags & MSG_OOB) {
                rc = -ENOTSUPP;
                goto out;
        }

        iov.iov_base = kaddr + offset;
        iov.iov_len = size;
        iov_iter_kvec(&msg_iter, WRITE, &iov, 1, size);
        rc = tls_push_data(sk, &msg_iter, size,
                           flags, TLS_RECORD_TYPE_DATA);
        kunmap(page);

out:
        release_sock(sk);
        return rc;
}

struct tls_record_info *tls_get_record(struct tls_offload_context_tx *context,
                                       u32 seq, u64 *p_record_sn)
{
        u64 record_sn = context->hint_record_sn;
        struct tls_record_info *info;

        info = context->retransmit_hint;
        if (!info ||
            before(seq, info->end_seq - info->len)) {
                /* if retransmit_hint is irrelevant start
                 * from the beggining of the list
                 */
                info = list_first_entry(&context->records_list,
                                        struct tls_record_info, list);
                record_sn = context->unacked_record_sn;
        }

        list_for_each_entry_from(info, &context->records_list, list) {
                if (before(seq, info->end_seq)) {
                        if (!context->retransmit_hint ||
                            after(info->end_seq,
                                  context->retransmit_hint->end_seq)) {
                                context->hint_record_sn = record_sn;
                                context->retransmit_hint = info;
                        }
                        *p_record_sn = record_sn;
                        return info;
                }
                record_sn++;
        }

        return NULL;
}
EXPORT_SYMBOL(tls_get_record);

static int tls_device_push_pending_record(struct sock *sk, int flags)
{
        struct iov_iter msg_iter;

        iov_iter_kvec(&msg_iter, WRITE, NULL, 0, 0);
        return tls_push_data(sk, &msg_iter, 0, flags, TLS_RECORD_TYPE_DATA);
}

void tls_device_write_space(struct sock *sk, struct tls_context *ctx)
{
        if (!sk->sk_write_pending && tls_is_partially_sent_record(ctx)) {
                gfp_t sk_allocation = sk->sk_allocation;

                sk->sk_allocation = GFP_ATOMIC;
                tls_push_partial_record(sk, ctx,
                                        MSG_DONTWAIT | MSG_NOSIGNAL |
                                        MSG_SENDPAGE_DECRYPTED);
                sk->sk_allocation = sk_allocation;
        }
}

static void tls_device_resync_rx(struct tls_context *tls_ctx,
                                 struct sock *sk, u32 seq, u8 *rcd_sn)
{
        struct net_device *netdev;

        if (WARN_ON(test_and_set_bit(TLS_RX_SYNC_RUNNING, &tls_ctx->flags)))
                return;
        netdev = READ_ONCE(tls_ctx->netdev);
        if (netdev)
                netdev->tlsdev_ops->tls_dev_resync(netdev, sk, seq, rcd_sn,
                                                   TLS_OFFLOAD_CTX_DIR_RX);
        clear_bit_unlock(TLS_RX_SYNC_RUNNING, &tls_ctx->flags);
}

void tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_offload_context_rx *rx_ctx;
        u8 rcd_sn[TLS_MAX_REC_SEQ_SIZE];
        struct tls_prot_info *prot;
        u32 is_req_pending;
        s64 resync_req;
        u32 req_seq;

        if (tls_ctx->rx_conf != TLS_HW)
                return;

        prot = &tls_ctx->prot_info;
        rx_ctx = tls_offload_ctx_rx(tls_ctx);
        memcpy(rcd_sn, tls_ctx->rx.rec_seq, prot->rec_seq_size);

        switch (rx_ctx->resync_type) {
        case TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ:
                resync_req = atomic64_read(&rx_ctx->resync_req);
                req_seq = resync_req >> 32;
                seq += TLS_HEADER_SIZE - 1;
                is_req_pending = resync_req;

                if (likely(!is_req_pending) || req_seq != seq ||
                    !atomic64_try_cmpxchg(&rx_ctx->resync_req, &resync_req, 0))
                        return;
                break;
        case TLS_OFFLOAD_SYNC_TYPE_CORE_NEXT_HINT:
                if (likely(!rx_ctx->resync_nh_do_now))
                        return;

                /* head of next rec is already in, note that the sock_inq will
                 * include the currently parsed message when called from parser
                 */
                if (tcp_inq(sk) > rcd_len)
                        return;

                rx_ctx->resync_nh_do_now = 0;
                seq += rcd_len;
                tls_bigint_increment(rcd_sn, prot->rec_seq_size);
                break;
        }

        tls_device_resync_rx(tls_ctx, sk, seq, rcd_sn);
}

static void tls_device_core_ctrl_rx_resync(struct tls_context *tls_ctx,
                                           struct tls_offload_context_rx *ctx,
                                           struct sock *sk, struct sk_buff *skb)
{
        struct strp_msg *rxm;

        /* device will request resyncs by itself based on stream scan */
        if (ctx->resync_type != TLS_OFFLOAD_SYNC_TYPE_CORE_NEXT_HINT)
                return;
        /* already scheduled */
        if (ctx->resync_nh_do_now)
                return;
        /* seen decrypted fragments since last fully-failed record */
        if (ctx->resync_nh_reset) {
                ctx->resync_nh_reset = 0;
                ctx->resync_nh.decrypted_failed = 1;
                ctx->resync_nh.decrypted_tgt = TLS_DEVICE_RESYNC_NH_START_IVAL;
                return;
        }

        if (++ctx->resync_nh.decrypted_failed <= ctx->resync_nh.decrypted_tgt)
                return;

        /* doing resync, bump the next target in case it fails */
        if (ctx->resync_nh.decrypted_tgt < TLS_DEVICE_RESYNC_NH_MAX_IVAL)
                ctx->resync_nh.decrypted_tgt *= 2;
        else
                ctx->resync_nh.decrypted_tgt += TLS_DEVICE_RESYNC_NH_MAX_IVAL;

        rxm = strp_msg(skb);

        /* head of next rec is already in, parser will sync for us */
        if (tcp_inq(sk) > rxm->full_len) {
                ctx->resync_nh_do_now = 1;
        } else {
                struct tls_prot_info *prot = &tls_ctx->prot_info;
                u8 rcd_sn[TLS_MAX_REC_SEQ_SIZE];

                memcpy(rcd_sn, tls_ctx->rx.rec_seq, prot->rec_seq_size);
                tls_bigint_increment(rcd_sn, prot->rec_seq_size);

                tls_device_resync_rx(tls_ctx, sk, tcp_sk(sk)->copied_seq,
                                     rcd_sn);
        }
}

static int tls_device_reencrypt(struct sock *sk, struct sk_buff *skb)
{
        struct strp_msg *rxm = strp_msg(skb);
        int err = 0, offset = rxm->offset, copy, nsg, data_len, pos;
        struct sk_buff *skb_iter, *unused;
        struct scatterlist sg[1];
        char *orig_buf, *buf;

        orig_buf = kmalloc(rxm->full_len + TLS_HEADER_SIZE +
                           TLS_CIPHER_AES_GCM_128_IV_SIZE, sk->sk_allocation);
        if (!orig_buf)
                return -ENOMEM;
        buf = orig_buf;

        nsg = skb_cow_data(skb, 0, &unused);
        if (unlikely(nsg < 0)) {
                err = nsg;
                goto free_buf;
        }

        sg_init_table(sg, 1);
        sg_set_buf(&sg[0], buf,
                   rxm->full_len + TLS_HEADER_SIZE +
                   TLS_CIPHER_AES_GCM_128_IV_SIZE);
        err = skb_copy_bits(skb, offset, buf,
                            TLS_HEADER_SIZE + TLS_CIPHER_AES_GCM_128_IV_SIZE);
        if (err)
                goto free_buf;

        /* We are interested only in the decrypted data not the auth */
        err = decrypt_skb(sk, skb, sg);
        if (err != -EBADMSG)
                goto free_buf;
        else
                err = 0;

        data_len = rxm->full_len - TLS_CIPHER_AES_GCM_128_TAG_SIZE;

        if (skb_pagelen(skb) > offset) {
                copy = min_t(int, skb_pagelen(skb) - offset, data_len);

                if (skb->decrypted) {
                        err = skb_store_bits(skb, offset, buf, copy);
                        if (err)
                                goto free_buf;
                }

                offset += copy;
                buf += copy;
        }

        pos = skb_pagelen(skb);
        skb_walk_frags(skb, skb_iter) {
                int frag_pos;

                /* Practically all frags must belong to msg if reencrypt
                 * is needed with current strparser and coalescing logic,
                 * but strparser may "get optimized", so let's be safe.
                 */
                if (pos + skb_iter->len <= offset)
                        goto done_with_frag;
                if (pos >= data_len + rxm->offset)
                        break;

                frag_pos = offset - pos;
                copy = min_t(int, skb_iter->len - frag_pos,
                             data_len + rxm->offset - offset);

                if (skb_iter->decrypted) {
                        err = skb_store_bits(skb_iter, frag_pos, buf, copy);
                        if (err)
                                goto free_buf;
                }

                offset += copy;
                buf += copy;
done_with_frag:
                pos += skb_iter->len;
        }

free_buf:
        kfree(orig_buf);
        return err;
}

int tls_device_decrypted(struct sock *sk, struct sk_buff *skb)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_offload_context_rx *ctx = tls_offload_ctx_rx(tls_ctx);
        int is_decrypted = skb->decrypted;
        int is_encrypted = !is_decrypted;
        struct sk_buff *skb_iter;

        /* Check if all the data is decrypted already */
        skb_walk_frags(skb, skb_iter) {
                is_decrypted &= skb_iter->decrypted;
                is_encrypted &= !skb_iter->decrypted;
        }

        ctx->sw.decrypted |= is_decrypted;

        /* Return immediately if the record is either entirely plaintext or
         * entirely ciphertext. Otherwise handle reencrypt partially decrypted
         * record.
         */
        if (is_decrypted) {
                ctx->resync_nh_reset = 1;
                return 0;
        }
        if (is_encrypted) {
                tls_device_core_ctrl_rx_resync(tls_ctx, ctx, sk, skb);
                return 0;
        }

        ctx->resync_nh_reset = 1;
        return tls_device_reencrypt(sk, skb);
}

static void tls_device_attach(struct tls_context *ctx, struct sock *sk,
                              struct net_device *netdev)
{
        if (sk->sk_destruct != tls_device_sk_destruct) {
                refcount_set(&ctx->refcount, 1);
                dev_hold(netdev);
                ctx->netdev = netdev;
                spin_lock_irq(&tls_device_lock);
                list_add_tail(&ctx->list, &tls_device_list);
                spin_unlock_irq(&tls_device_lock);

                ctx->sk_destruct = sk->sk_destruct;
                sk->sk_destruct = tls_device_sk_destruct;
        }
}

int tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
{
        u16 nonce_size, tag_size, iv_size, rec_seq_size;
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_prot_info *prot = &tls_ctx->prot_info;
        struct tls_record_info *start_marker_record;
        struct tls_offload_context_tx *offload_ctx;
        struct tls_crypto_info *crypto_info;
        struct net_device *netdev;
        char *iv, *rec_seq;
        struct sk_buff *skb;
        int rc = -EINVAL;
        __be64 rcd_sn;

        if (!ctx)
                goto out;

        if (ctx->priv_ctx_tx) {
                rc = -EEXIST;
                goto out;
        }

        start_marker_record = kmalloc(sizeof(*start_marker_record), GFP_KERNEL);
        if (!start_marker_record) {
                rc = -ENOMEM;
                goto out;
        }

        offload_ctx = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_TX, GFP_KERNEL);
        if (!offload_ctx) {
                rc = -ENOMEM;
                goto free_marker_record;
        }

        crypto_info = &ctx->crypto_send.info;
        if (crypto_info->version != TLS_1_2_VERSION) {
                rc = -EOPNOTSUPP;
                goto free_offload_ctx;
        }

        switch (crypto_info->cipher_type) {
        case TLS_CIPHER_AES_GCM_128:
                nonce_size = TLS_CIPHER_AES_GCM_128_IV_SIZE;
                tag_size = TLS_CIPHER_AES_GCM_128_TAG_SIZE;
                iv_size = TLS_CIPHER_AES_GCM_128_IV_SIZE;
                iv = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->iv;
                rec_seq_size = TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE;
                rec_seq =
                 ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->rec_seq;
                break;
        default:
                rc = -EINVAL;
                goto free_offload_ctx;
        }

        /* Sanity-check the rec_seq_size for stack allocations */
        if (rec_seq_size > TLS_MAX_REC_SEQ_SIZE) {
                rc = -EINVAL;
                goto free_offload_ctx;
        }

        prot->version = crypto_info->version;
        prot->cipher_type = crypto_info->cipher_type;
        prot->prepend_size = TLS_HEADER_SIZE + nonce_size;
        prot->tag_size = tag_size;
        prot->overhead_size = prot->prepend_size + prot->tag_size;
        prot->iv_size = iv_size;
        ctx->tx.iv = kmalloc(iv_size + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
                             GFP_KERNEL);
        if (!ctx->tx.iv) {
                rc = -ENOMEM;
                goto free_offload_ctx;
        }

        memcpy(ctx->tx.iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv, iv_size);

        prot->rec_seq_size = rec_seq_size;
        ctx->tx.rec_seq = kmemdup(rec_seq, rec_seq_size, GFP_KERNEL);
        if (!ctx->tx.rec_seq) {
                rc = -ENOMEM;
                goto free_iv;
        }

        rc = tls_sw_fallback_init(sk, offload_ctx, crypto_info);
        if (rc)
                goto free_rec_seq;

        /* start at rec_seq - 1 to account for the start marker record */
        memcpy(&rcd_sn, ctx->tx.rec_seq, sizeof(rcd_sn));
        offload_ctx->unacked_record_sn = be64_to_cpu(rcd_sn) - 1;

        start_marker_record->end_seq = tcp_sk(sk)->write_seq;
        start_marker_record->len = 0;
        start_marker_record->num_frags = 0;

        INIT_LIST_HEAD(&offload_ctx->records_list);
        list_add_tail(&start_marker_record->list, &offload_ctx->records_list);
        spin_lock_init(&offload_ctx->lock);
        sg_init_table(offload_ctx->sg_tx_data,
                      ARRAY_SIZE(offload_ctx->sg_tx_data));

        clean_acked_data_enable(inet_csk(sk), &tls_icsk_clean_acked);
        ctx->push_pending_record = tls_device_push_pending_record;

        /* TLS offload is greatly simplified if we don't send
         * SKBs where only part of the payload needs to be encrypted.
         * So mark the last skb in the write queue as end of record.
         */
        skb = tcp_write_queue_tail(sk);
        if (skb)
                TCP_SKB_CB(skb)->eor = 1;

        /* We support starting offload on multiple sockets
         * concurrently, so we only need a read lock here.
         * This lock must precede get_netdev_for_sock to prevent races between
         * NETDEV_DOWN and setsockopt.
         */
        down_read(&device_offload_lock);
        netdev = get_netdev_for_sock(sk);
        if (!netdev) {
                pr_err_ratelimited("%s: netdev not found\n", __func__);
                rc = -EINVAL;
                goto release_lock;
        }

        if (!(netdev->features & NETIF_F_HW_TLS_TX)) {
                rc = -ENOTSUPP;
                goto release_netdev;
        }

        /* Avoid offloading if the device is down
         * We don't want to offload new flows after
         * the NETDEV_DOWN event
         */
        if (!(netdev->flags & IFF_UP)) {
                rc = -EINVAL;
                goto release_netdev;
        }

        ctx->priv_ctx_tx = offload_ctx;
        rc = netdev->tlsdev_ops->tls_dev_add(netdev, sk, TLS_OFFLOAD_CTX_DIR_TX,
                                             &ctx->crypto_send.info,
                                             tcp_sk(sk)->write_seq);
        if (rc)
                goto release_netdev;

        tls_device_attach(ctx, sk, netdev);

        /* following this assignment tls_is_sk_tx_device_offloaded
         * will return true and the context might be accessed
         * by the netdev's xmit function.
         */
        smp_store_release(&sk->sk_validate_xmit_skb, tls_validate_xmit_skb);
        dev_put(netdev);
        up_read(&device_offload_lock);
        goto out;

release_netdev:
        dev_put(netdev);
release_lock:
        up_read(&device_offload_lock);
        clean_acked_data_disable(inet_csk(sk));
        crypto_free_aead(offload_ctx->aead_send);
free_rec_seq:
        kfree(ctx->tx.rec_seq);
free_iv:
        kfree(ctx->tx.iv);
free_offload_ctx:
        kfree(offload_ctx);
        ctx->priv_ctx_tx = NULL;
free_marker_record:

        kfree(start_marker_record);
out:
        return rc;
}

int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
{
        struct tls_offload_context_rx *context;
        struct net_device *netdev;
        int rc = 0;

        if (ctx->crypto_recv.info.version != TLS_1_2_VERSION)
                return -EOPNOTSUPP;

        /* We support starting offload on multiple sockets
         * concurrently, so we only need a read lock here.
         * This lock must precede get_netdev_for_sock to prevent races between
         * NETDEV_DOWN and setsockopt.
         */
        down_read(&device_offload_lock);
        netdev = get_netdev_for_sock(sk);
        if (!netdev) {
                pr_err_ratelimited("%s: netdev not found\n", __func__);
                rc = -EINVAL;
                goto release_lock;
        }

        if (!(netdev->features & NETIF_F_HW_TLS_RX)) {
                rc = -ENOTSUPP;
                goto release_netdev;
        }

        /* Avoid offloading if the device is down
         * We don't want to offload new flows after
         * the NETDEV_DOWN event
         */
        if (!(netdev->flags & IFF_UP)) {
                rc = -EINVAL;
                goto release_netdev;
        }

        context = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_RX, GFP_KERNEL);
        if (!context) {
                rc = -ENOMEM;
                goto release_netdev;
        }
        context->resync_nh_reset = 1;

        ctx->priv_ctx_rx = context;
        rc = tls_set_sw_offload(sk, ctx, 0);
        if (rc)
                goto release_ctx;

        rc = netdev->tlsdev_ops->tls_dev_add(netdev, sk, TLS_OFFLOAD_CTX_DIR_RX,
                                             &ctx->crypto_recv.info,
                                             tcp_sk(sk)->copied_seq);
        if (rc)
                goto free_sw_resources;

        tls_device_attach(ctx, sk, netdev);
        goto release_netdev;

free_sw_resources:
        up_read(&device_offload_lock);
        tls_sw_free_resources_rx(sk);
        down_read(&device_offload_lock);
release_ctx:
        ctx->priv_ctx_rx = NULL;
release_netdev:
        dev_put(netdev);
release_lock:
        up_read(&device_offload_lock);
        return rc;
}

void tls_device_offload_cleanup_rx(struct sock *sk)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct net_device *netdev;

        down_read(&device_offload_lock);
        netdev = tls_ctx->netdev;
        if (!netdev)
                goto out;

        netdev->tlsdev_ops->tls_dev_del(netdev, tls_ctx,
                                        TLS_OFFLOAD_CTX_DIR_RX);

        if (tls_ctx->tx_conf != TLS_HW) {
                dev_put(netdev);
                tls_ctx->netdev = NULL;
        }
out:
        up_read(&device_offload_lock);
        tls_sw_release_resources_rx(sk);
}

static int tls_device_down(struct net_device *netdev)
{
        struct tls_context *ctx, *tmp;
        unsigned long flags;
        LIST_HEAD(list);

        /* Request a write lock to block new offload attempts */
        down_write(&device_offload_lock);

        spin_lock_irqsave(&tls_device_lock, flags);
        list_for_each_entry_safe(ctx, tmp, &tls_device_list, list) {
                if (ctx->netdev != netdev ||
                    !refcount_inc_not_zero(&ctx->refcount))
                        continue;

                list_move(&ctx->list, &list);
        }
        spin_unlock_irqrestore(&tls_device_lock, flags);

        list_for_each_entry_safe(ctx, tmp, &list, list) {
                if (ctx->tx_conf == TLS_HW)
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_TX);
                if (ctx->rx_conf == TLS_HW)
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_RX);
                WRITE_ONCE(ctx->netdev, NULL);
                smp_mb__before_atomic(); /* pairs with test_and_set_bit() */
                while (test_bit(TLS_RX_SYNC_RUNNING, &ctx->flags))
                        usleep_range(10, 200);
                dev_put(netdev);
                list_del_init(&ctx->list);

                if (refcount_dec_and_test(&ctx->refcount))
                        tls_device_free_ctx(ctx);
        }

        up_write(&device_offload_lock);

        flush_work(&tls_device_gc_work);

        return NOTIFY_DONE;
}

static int tls_dev_event(struct notifier_block *this, unsigned long event,
                         void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);

        if (!dev->tlsdev_ops &&
            !(dev->features & (NETIF_F_HW_TLS_RX | NETIF_F_HW_TLS_TX)))
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_REGISTER:
        case NETDEV_FEAT_CHANGE:
                if ((dev->features & NETIF_F_HW_TLS_RX) &&
                    !dev->tlsdev_ops->tls_dev_resync)
                        return NOTIFY_BAD;

                if  (dev->tlsdev_ops &&
                     dev->tlsdev_ops->tls_dev_add &&
                     dev->tlsdev_ops->tls_dev_del)
                        return NOTIFY_DONE;
                else
                        return NOTIFY_BAD;
        case NETDEV_DOWN:
                return tls_device_down(dev);
        }
        return NOTIFY_DONE;
}

static struct notifier_block tls_dev_notifier = {
        .notifier_call  = tls_dev_event,
};

void __init tls_device_init(void)
{
        register_netdevice_notifier(&tls_dev_notifier);
}

void __exit tls_device_cleanup(void)
{
        unregister_netdevice_notifier(&tls_dev_notifier);
        flush_work(&tls_device_gc_work);
        clean_acked_data_flush();
}