/* 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>
#include <linux/skbuff_ref.h>

#include "tls.h"
#include "trace.h"

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

static struct workqueue_struct *destruct_wq __read_mostly;

static LIST_HEAD(tls_device_list);
static LIST_HEAD(tls_device_down_list);
static DEFINE_SPINLOCK(tls_device_lock);

static struct page *dummy_page;

static void tls_device_free_ctx(struct tls_context *ctx)
{
        if (ctx->tx_conf == TLS_HW)
                kfree(tls_offload_ctx_tx(ctx));

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

        tls_ctx_free(NULL, ctx);
}

static void tls_device_tx_del_task(struct work_struct *work)
{
        struct tls_offload_context_tx *offload_ctx =
                container_of(work, struct tls_offload_context_tx, destruct_work);
        struct tls_context *ctx = offload_ctx->ctx;
        struct net_device *netdev;

        /* Safe, because this is the destroy flow, refcount is 0, so
         * tls_device_down can't store this field in parallel.
         */
        netdev = rcu_dereference_protected(ctx->netdev,
                                           !refcount_read(&ctx->refcount));

        netdev->tlsdev_ops->tls_dev_del(netdev, ctx, TLS_OFFLOAD_CTX_DIR_TX);
        dev_put(netdev);
        ctx->netdev = NULL;
        tls_device_free_ctx(ctx);
}

static void tls_device_queue_ctx_destruction(struct tls_context *ctx)
{
        struct net_device *netdev;
        unsigned long flags;
        bool async_cleanup;

        spin_lock_irqsave(&tls_device_lock, flags);
        if (unlikely(!refcount_dec_and_test(&ctx->refcount))) {
                spin_unlock_irqrestore(&tls_device_lock, flags);
                return;
        }

        list_del(&ctx->list); /* Remove from tls_device_list / tls_device_down_list */

        /* Safe, because this is the destroy flow, refcount is 0, so
         * tls_device_down can't store this field in parallel.
         */
        netdev = rcu_dereference_protected(ctx->netdev,
                                           !refcount_read(&ctx->refcount));

        async_cleanup = netdev && ctx->tx_conf == TLS_HW;
        if (async_cleanup) {
                struct tls_offload_context_tx *offload_ctx = tls_offload_ctx_tx(ctx);

                /* queue_work inside the spinlock
                 * to make sure tls_device_down waits for that work.
                 */
                queue_work(destruct_wq, &offload_ctx->destruct_work);
        }
        spin_unlock_irqrestore(&tls_device_lock, flags);

        if (!async_cleanup)
                tls_device_free_ctx(ctx);
}

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

        rcu_read_lock();
        dst = __sk_dst_get(sk);
        dev = dst ? dst_dev_rcu(dst) : NULL;
        if (likely(dev)) {
                lowest_dev = netdev_sk_get_lowest_dev(dev, sk);
                dev_hold(lowest_dev);
        }
        rcu_read_unlock();

        return lowest_dev;
}

static void destroy_record(struct tls_record_info *record)
{
        int i;

        for (i = 0; i < record->num_frags; i++)
                __skb_frag_unref(&record->frags[i], false);
        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_tcp_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_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.
 */
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(tcp_sk(sk));
        }

        tls_device_queue_ctx_destruction(tls_ctx);
}
EXPORT_SYMBOL_GPL(tls_device_sk_destruct);

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);
}

void tls_offload_tx_resync_request(struct sock *sk, u32 got_seq, u32 exp_seq)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);

        trace_tls_device_tx_resync_req(sk, got_seq, exp_seq);
        WARN_ON(test_and_set_bit(TLS_TX_SYNC_SCHED, &tls_ctx->flags));
}
EXPORT_SYMBOL_GPL(tls_offload_tx_resync_request);

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

        tcp_write_collapse_fence(sk);
        rcd_sn = tls_ctx->tx.rec_seq;

        trace_tls_device_tx_resync_send(sk, seq, rcd_sn);
        down_read(&device_offload_lock);
        netdev = rcu_dereference_protected(tls_ctx->netdev,
                                           lockdep_is_held(&device_offload_lock));
        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 (skb_frag_page(frag) == pfrag->page &&
            skb_frag_off(frag) + skb_frag_size(frag) == pfrag->offset) {
                skb_frag_size_add(frag, size);
        } else {
                ++frag;
                skb_frag_fill_page_desc(frag, pfrag->page, pfrag->offset,
                                        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,
                           int flags)
{
        struct tls_prot_info *prot = &ctx->prot_info;
        struct tcp_sock *tp = tcp_sk(sk);
        skb_frag_t *frag;
        int i;

        record->end_seq = tp->write_seq + record->len;
        list_add_tail_rcu(&record->list, &offload_ctx->records_list);
        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),
                            skb_frag_size(frag), skb_frag_off(frag));
                sk_mem_charge(sk, skb_frag_size(frag));
                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 void tls_device_record_close(struct sock *sk,
                                    struct tls_context *ctx,
                                    struct tls_record_info *record,
                                    struct page_frag *pfrag,
                                    unsigned char record_type)
{
        struct tls_prot_info *prot = &ctx->prot_info;
        struct page_frag dummy_tag_frag;

        /* append tag
         * device will fill in the tag, we just need to append a placeholder
         * use socket memory to improve coalescing (re-using a single buffer
         * increases frag count)
         * if we can't allocate memory now use the dummy page
         */
        if (unlikely(pfrag->size - pfrag->offset < prot->tag_size) &&
            !skb_page_frag_refill(prot->tag_size, pfrag, sk->sk_allocation)) {
                dummy_tag_frag.page = dummy_page;
                dummy_tag_frag.offset = 0;
                pfrag = &dummy_tag_frag;
        }
        tls_append_frag(record, pfrag, prot->tag_size);

        /* fill prepend */
        tls_fill_prepend(ctx, skb_frag_address(&record->frags[0]),
                         record->len - prot->overhead_size,
                         record_type);
}

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_obj(*record);
        if (!record)
                return -ENOMEM;

        frag = &record->frags[0];
        skb_frag_fill_page_desc(frag, pfrag->page, pfrag->offset,
                                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))) {
                        if (!sk->sk_bypass_prot_mem)
                                READ_ONCE(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_device_copy_data(void *addr, size_t bytes, struct iov_iter *i)
{
        size_t pre_copy, nocache;

        pre_copy = ~((unsigned long)addr - 1) & (SMP_CACHE_BYTES - 1);
        if (pre_copy) {
                pre_copy = min(pre_copy, bytes);
                if (copy_from_iter(addr, pre_copy, i) != pre_copy)
                        return -EFAULT;
                bytes -= pre_copy;
                addr += pre_copy;
        }

        nocache = round_down(bytes, SMP_CACHE_BYTES);
        if (copy_from_iter_nocache(addr, nocache, i) != nocache)
                return -EFAULT;
        bytes -= nocache;
        addr += nocache;

        if (bytes && copy_from_iter(addr, bytes, i) != bytes)
                return -EFAULT;

        return 0;
}

static int tls_push_data(struct sock *sk,
                         struct iov_iter *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);
        struct tls_record_info *record;
        int tls_push_record_flags;
        struct page_frag *pfrag;
        size_t orig_size = size;
        u32 max_open_record_len;
        bool more = false;
        bool done = false;
        int copy, rc = 0;
        long timeo;

        if (flags &
            ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
              MSG_SPLICE_PAGES | MSG_EOR))
                return -EOPNOTSUPP;

        if ((flags & (MSG_MORE | MSG_EOR)) == (MSG_MORE | MSG_EOR))
                return -EINVAL;

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

        flags |= MSG_SENDPAGE_DECRYPTED;
        tls_push_record_flags = flags | MSG_MORE;

        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_ctx->tx_max_payload_len +
                              prot->prepend_size;
        do {
                rc = tls_do_allocation(sk, ctx, pfrag, prot->prepend_size);
                if (unlikely(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, max_open_record_len - record->len);
                if (copy && (flags & MSG_SPLICE_PAGES)) {
                        struct page_frag zc_pfrag;
                        struct page **pages = &zc_pfrag.page;
                        size_t off;

                        rc = iov_iter_extract_pages(iter, &pages,
                                                    copy, 1, 0, &off);
                        if (rc <= 0) {
                                if (rc == 0)
                                        rc = -EIO;
                                goto handle_error;
                        }
                        copy = rc;

                        if (WARN_ON_ONCE(!sendpage_ok(zc_pfrag.page))) {
                                iov_iter_revert(iter, copy);
                                rc = -EIO;
                                goto handle_error;
                        }

                        zc_pfrag.offset = off;
                        zc_pfrag.size = copy;
                        tls_append_frag(record, &zc_pfrag, copy);
                } else if (copy) {
                        copy = min_t(size_t, copy, pfrag->size - pfrag->offset);

                        rc = tls_device_copy_data(page_address(pfrag->page) +
                                                  pfrag->offset, copy,
                                                  iter);
                        if (rc)
                                goto handle_error;
                        tls_append_frag(record, pfrag, copy);
                }

                size -= copy;
                if (!size) {
last_record:
                        tls_push_record_flags = flags;
                        if (flags & MSG_MORE) {
                                more = true;
                                break;
                        }

                        done = true;
                }

                if (done || record->len >= max_open_record_len ||
                    (record->num_frags >= MAX_SKB_FRAGS - 1)) {
                        tls_device_record_close(sk, tls_ctx, record,
                                                pfrag, record_type);

                        rc = tls_push_record(sk,
                                             tls_ctx,
                                             ctx,
                                             record,
                                             tls_push_record_flags);
                        if (rc < 0)
                                break;
                }
        } while (!done);

        tls_ctx->pending_open_record_frags = more;

        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;
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        int rc;

        if (!tls_ctx->zerocopy_sendfile)
                msg->msg_flags &= ~MSG_SPLICE_PAGES;

        mutex_lock(&tls_ctx->tx_lock);
        lock_sock(sk);

        if (unlikely(msg->msg_controllen)) {
                rc = tls_process_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);
        mutex_unlock(&tls_ctx->tx_lock);
        return rc;
}

void tls_device_splice_eof(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct iov_iter iter = {};

        if (!tls_is_partially_sent_record(tls_ctx) &&
            !tls_is_pending_open_record(tls_ctx))
                return;

        mutex_lock(&tls_ctx->tx_lock);
        lock_sock(sk);

        if (tls_is_partially_sent_record(tls_ctx) ||
            tls_is_pending_open_record(tls_ctx)) {
                iov_iter_bvec(&iter, ITER_SOURCE, NULL, 0, 0);
                tls_push_data(sk, &iter, 0, 0, TLS_RECORD_TYPE_DATA);
        }

        release_sock(sk);
        mutex_unlock(&tls_ctx->tx_lock);
}

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, *last;

        info = context->retransmit_hint;
        if (!info ||
            before(seq, info->end_seq - info->len)) {
                /* if retransmit_hint is irrelevant start
                 * from the beginning of the list
                 */
                info = list_first_entry_or_null(&context->records_list,
                                                struct tls_record_info, list);
                if (!info)
                        return NULL;
                /* send the start_marker record if seq number is before the
                 * tls offload start marker sequence number. This record is
                 * required to handle TCP packets which are before TLS offload
                 * started.
                 *  And if it's not start marker, look if this seq number
                 * belongs to the list.
                 */
                if (likely(!tls_record_is_start_marker(info))) {
                        /* we have the first record, get the last record to see
                         * if this seq number belongs to the list.
                         */
                        last = list_last_entry(&context->records_list,
                                               struct tls_record_info, list);

                        if (!between(seq, tls_record_start_seq(info),
                                     last->end_seq))
                                return NULL;
                }
                record_sn = context->unacked_record_sn;
        }

        /* We just need the _rcu for the READ_ONCE() */
        rcu_read_lock();
        list_for_each_entry_from_rcu(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;
                        goto exit_rcu_unlock;
                }
                record_sn++;
        }
        info = NULL;

exit_rcu_unlock:
        rcu_read_unlock();
        return info;
}
EXPORT_SYMBOL(tls_get_record);

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

        iov_iter_kvec(&iter, ITER_SOURCE, NULL, 0, 0);
        return tls_push_data(sk, &iter, 0, flags, TLS_RECORD_TYPE_DATA);
}

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

                WARN_ON_ONCE(sk->sk_write_pending);

                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 tls_offload_context_rx *rx_ctx = tls_offload_ctx_rx(tls_ctx);
        struct net_device *netdev;

        trace_tls_device_rx_resync_send(sk, seq, rcd_sn, rx_ctx->resync_type);
        rcu_read_lock();
        netdev = rcu_dereference(tls_ctx->netdev);
        if (netdev)
                netdev->tlsdev_ops->tls_dev_resync(netdev, sk, seq, rcd_sn,
                                                   TLS_OFFLOAD_CTX_DIR_RX);
        rcu_read_unlock();
        TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICERESYNC);
}

static bool
tls_device_rx_resync_async(struct tls_offload_resync_async *resync_async,
                           s64 resync_req, u32 *seq, u16 *rcd_delta)
{
        u32 is_async = resync_req & RESYNC_REQ_ASYNC;
        u32 req_seq = resync_req >> 32;
        u32 req_end = req_seq + ((resync_req >> 16) & 0xffff);
        u16 i;

        *rcd_delta = 0;

        if (is_async) {
                /* shouldn't get to wraparound:
                 * too long in async stage, something bad happened
                 */
                if (WARN_ON_ONCE(resync_async->rcd_delta == USHRT_MAX)) {
                        tls_offload_rx_resync_async_request_cancel(resync_async);
                        return false;
                }

                /* asynchronous stage: log all headers seq such that
                 * req_seq <= seq <= end_seq, and wait for real resync request
                 */
                if (before(*seq, req_seq))
                        return false;
                if (!after(*seq, req_end) &&
                    resync_async->loglen < TLS_DEVICE_RESYNC_ASYNC_LOGMAX)
                        resync_async->log[resync_async->loglen++] = *seq;

                resync_async->rcd_delta++;

                return false;
        }

        /* synchronous stage: check against the logged entries and
         * proceed to check the next entries if no match was found
         */
        for (i = 0; i < resync_async->loglen; i++)
                if (req_seq == resync_async->log[i] &&
                    atomic64_try_cmpxchg(&resync_async->req, &resync_req, 0)) {
                        *rcd_delta = resync_async->rcd_delta - i;
                        *seq = req_seq;
                        resync_async->loglen = 0;
                        resync_async->rcd_delta = 0;
                        return true;
                }

        resync_async->loglen = 0;
        resync_async->rcd_delta = 0;

        if (req_seq == *seq &&
            atomic64_try_cmpxchg(&resync_async->req,
                                 &resync_req, 0))
                return true;

        return false;
}

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];
        u32 sock_data, is_req_pending;
        struct tls_prot_info *prot;
        s64 resync_req;
        u16 rcd_delta;
        u32 req_seq;

        if (tls_ctx->rx_conf != TLS_HW)
                return;
        if (unlikely(test_bit(TLS_RX_DEV_DEGRADED, &tls_ctx->flags)))
                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
                 */
                sock_data = tcp_inq(sk);
                if (sock_data > rcd_len) {
                        trace_tls_device_rx_resync_nh_delay(sk, sock_data,
                                                            rcd_len);
                        return;
                }

                rx_ctx->resync_nh_do_now = 0;
                seq += rcd_len;
                tls_bigint_increment(rcd_sn, prot->rec_seq_size);
                break;
        case TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ_ASYNC:
                resync_req = atomic64_read(&rx_ctx->resync_async->req);
                is_req_pending = resync_req;
                if (likely(!is_req_pending))
                        return;

                if (!tls_device_rx_resync_async(rx_ctx->resync_async,
                                                resync_req, &seq, &rcd_delta))
                        return;
                tls_bigint_subtract(rcd_sn, rcd_delta);
                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) {
                trace_tls_device_rx_resync_nh_schedule(sk);
                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 tls_context *tls_ctx)
{
        struct tls_sw_context_rx *sw_ctx = tls_sw_ctx_rx(tls_ctx);
        const struct tls_cipher_desc *cipher_desc;
        int err, offset, copy, data_len, pos;
        struct sk_buff *skb, *skb_iter;
        struct scatterlist sg[1];
        struct strp_msg *rxm;
        char *orig_buf, *buf;

        cipher_desc = get_cipher_desc(tls_ctx->crypto_recv.info.cipher_type);
        DEBUG_NET_WARN_ON_ONCE(!cipher_desc || !cipher_desc->offloadable);

        rxm = strp_msg(tls_strp_msg(sw_ctx));
        orig_buf = kmalloc(rxm->full_len + TLS_HEADER_SIZE + cipher_desc->iv,
                           sk->sk_allocation);
        if (!orig_buf)
                return -ENOMEM;
        buf = orig_buf;

        err = tls_strp_msg_cow(sw_ctx);
        if (unlikely(err))
                goto free_buf;

        skb = tls_strp_msg(sw_ctx);
        rxm = strp_msg(skb);
        offset = rxm->offset;

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

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

        data_len = rxm->full_len - cipher_desc->tag;

        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 tls_context *tls_ctx)
{
        struct tls_offload_context_rx *ctx = tls_offload_ctx_rx(tls_ctx);
        struct tls_sw_context_rx *sw_ctx = tls_sw_ctx_rx(tls_ctx);
        struct sk_buff *skb = tls_strp_msg(sw_ctx);
        struct strp_msg *rxm = strp_msg(skb);
        int is_decrypted, is_encrypted;

        if (!tls_strp_msg_mixed_decrypted(sw_ctx)) {
                is_decrypted = skb->decrypted;
                is_encrypted = !is_decrypted;
        } else {
                is_decrypted = 0;
                is_encrypted = 0;
        }

        trace_tls_device_decrypted(sk, tcp_sk(sk)->copied_seq - rxm->full_len,
                                   tls_ctx->rx.rec_seq, rxm->full_len,
                                   is_encrypted, is_decrypted);

        if (unlikely(test_bit(TLS_RX_DEV_DEGRADED, &tls_ctx->flags))) {
                if (likely(is_encrypted || is_decrypted))
                        return is_decrypted;

                /* After tls_device_down disables the offload, the next SKB will
                 * likely have initial fragments decrypted, and final ones not
                 * decrypted. We need to reencrypt that single SKB.
                 */
                return tls_device_reencrypt(sk, tls_ctx);
        }

        /* 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 is_decrypted;
        }
        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, tls_ctx);
}

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);
                RCU_INIT_POINTER(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;
                smp_store_release(&sk->sk_destruct, tls_device_sk_destruct);
        }
}

static struct tls_offload_context_tx *alloc_offload_ctx_tx(struct tls_context *ctx)
{
        struct tls_offload_context_tx *offload_ctx;
        __be64 rcd_sn;

        offload_ctx = kzalloc_obj(*offload_ctx);
        if (!offload_ctx)
                return NULL;

        INIT_WORK(&offload_ctx->destruct_work, tls_device_tx_del_task);
        INIT_LIST_HEAD(&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));

        /* 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;

        offload_ctx->ctx = ctx;

        return offload_ctx;
}

int tls_set_device_offload(struct sock *sk)
{
        struct tls_record_info *start_marker_record;
        struct tls_offload_context_tx *offload_ctx;
        const struct tls_cipher_desc *cipher_desc;
        struct tls_crypto_info *crypto_info;
        struct tls_prot_info *prot;
        struct net_device *netdev;
        struct tls_context *ctx;
        char *iv, *rec_seq;
        int rc;

        ctx = tls_get_ctx(sk);
        prot = &ctx->prot_info;

        if (ctx->priv_ctx_tx)
                return -EEXIST;

        netdev = get_netdev_for_sock(sk);
        if (!netdev) {
                pr_err_ratelimited("%s: netdev not found\n", __func__);
                return -EINVAL;
        }

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

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

        cipher_desc = get_cipher_desc(crypto_info->cipher_type);
        if (!cipher_desc || !cipher_desc->offloadable) {
                rc = -EINVAL;
                goto release_netdev;
        }

        rc = init_prot_info(prot, crypto_info, cipher_desc);
        if (rc)
                goto release_netdev;

        iv = crypto_info_iv(crypto_info, cipher_desc);
        rec_seq = crypto_info_rec_seq(crypto_info, cipher_desc);

        memcpy(ctx->tx.iv + cipher_desc->salt, iv, cipher_desc->iv);
        memcpy(ctx->tx.rec_seq, rec_seq, cipher_desc->rec_seq);

        start_marker_record = kmalloc_obj(*start_marker_record);
        if (!start_marker_record) {
                rc = -ENOMEM;
                goto release_netdev;
        }

        offload_ctx = alloc_offload_ctx_tx(ctx);
        if (!offload_ctx) {
                rc = -ENOMEM;
                goto free_marker_record;
        }

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

        start_marker_record->end_seq = tcp_sk(sk)->write_seq;
        start_marker_record->len = 0;
        start_marker_record->num_frags = 0;
        list_add_tail(&start_marker_record->list, &offload_ctx->records_list);

        clean_acked_data_enable(tcp_sk(sk), &tls_tcp_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.
         */
        tcp_write_collapse_fence(sk);

        /* Avoid offloading if the device is down
         * We don't want to offload new flows after
         * the NETDEV_DOWN event
         *
         * device_offload_lock is taken in tls_devices's NETDEV_DOWN
         * handler thus protecting from the device going down before
         * ctx was added to tls_device_list.
         */
        down_read(&device_offload_lock);
        if (!(netdev->flags & IFF_UP)) {
                rc = -EINVAL;
                goto release_lock;
        }

        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);
        trace_tls_device_offload_set(sk, TLS_OFFLOAD_CTX_DIR_TX,
                                     tcp_sk(sk)->write_seq, rec_seq, rc);
        if (rc)
                goto release_lock;

        tls_device_attach(ctx, sk, netdev);
        up_read(&device_offload_lock);

        /* following this assignment tls_is_skb_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);

        return 0;

release_lock:
        up_read(&device_offload_lock);
        clean_acked_data_disable(tcp_sk(sk));
        crypto_free_aead(offload_ctx->aead_send);
free_offload_ctx:
        kfree(offload_ctx);
        ctx->priv_ctx_tx = NULL;
free_marker_record:
        kfree(start_marker_record);
release_netdev:
        dev_put(netdev);
        return rc;
}

int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
{
        struct tls12_crypto_info_aes_gcm_128 *info;
        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;

        netdev = get_netdev_for_sock(sk);
        if (!netdev) {
                pr_err_ratelimited("%s: netdev not found\n", __func__);
                return -EINVAL;
        }

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

        /* Avoid offloading if the device is down
         * We don't want to offload new flows after
         * the NETDEV_DOWN event
         *
         * device_offload_lock is taken in tls_devices's NETDEV_DOWN
         * handler thus protecting from the device going down before
         * ctx was added to tls_device_list.
         */
        down_read(&device_offload_lock);
        if (!(netdev->flags & IFF_UP)) {
                rc = -EINVAL;
                goto release_lock;
        }

        context = kzalloc_obj(*context);
        if (!context) {
                rc = -ENOMEM;
                goto release_lock;
        }
        context->resync_nh_reset = 1;

        ctx->priv_ctx_rx = context;
        rc = tls_set_sw_offload(sk, 0, NULL);
        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);
        info = (void *)&ctx->crypto_recv.info;
        trace_tls_device_offload_set(sk, TLS_OFFLOAD_CTX_DIR_RX,
                                     tcp_sk(sk)->copied_seq, info->rec_seq, rc);
        if (rc)
                goto free_sw_resources;

        tls_device_attach(ctx, sk, netdev);
        up_read(&device_offload_lock);

        dev_put(netdev);

        return 0;

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_lock:
        up_read(&device_offload_lock);
release_netdev:
        dev_put(netdev);
        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 = rcu_dereference_protected(tls_ctx->netdev,
                                           lockdep_is_held(&device_offload_lock));
        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);
                rcu_assign_pointer(tls_ctx->netdev, NULL);
        } else {
                set_bit(TLS_RX_DEV_CLOSED, &tls_ctx->flags);
        }
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) {
                struct net_device *ctx_netdev =
                        rcu_dereference_protected(ctx->netdev,
                                                  lockdep_is_held(&device_offload_lock));

                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) {
                /* Stop offloaded TX and switch to the fallback.
                 * tls_is_skb_tx_device_offloaded will return false.
                 */
                WRITE_ONCE(ctx->sk->sk_validate_xmit_skb, tls_validate_xmit_skb_sw);

                /* Stop the RX and TX resync.
                 * tls_dev_resync must not be called after tls_dev_del.
                 */
                rcu_assign_pointer(ctx->netdev, NULL);

                /* Start skipping the RX resync logic completely. */
                set_bit(TLS_RX_DEV_DEGRADED, &ctx->flags);

                /* Sync with inflight packets. After this point:
                 * TX: no non-encrypted packets will be passed to the driver.
                 * RX: resync requests from the driver will be ignored.
                 */
                synchronize_net();

                /* Release the offload context on the driver side. */
                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 &&
                    !test_bit(TLS_RX_DEV_CLOSED, &ctx->flags))
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_RX);

                dev_put(netdev);

                /* Move the context to a separate list for two reasons:
                 * 1. When the context is deallocated, list_del is called.
                 * 2. It's no longer an offloaded context, so we don't want to
                 *    run offload-specific code on this context.
                 */
                spin_lock_irqsave(&tls_device_lock, flags);
                list_move_tail(&ctx->list, &tls_device_down_list);
                spin_unlock_irqrestore(&tls_device_lock, flags);

                /* Device contexts for RX and TX will be freed in on sk_destruct
                 * by tls_device_free_ctx. rx_conf and tx_conf stay in TLS_HW.
                 * Now release the ref taken above.
                 */
                if (refcount_dec_and_test(&ctx->refcount)) {
                        /* sk_destruct ran after tls_device_down took a ref, and
                         * it returned early. Complete the destruction here.
                         */
                        list_del(&ctx->list);
                        tls_device_free_ctx(ctx);
                }
        }

        up_write(&device_offload_lock);

        flush_workqueue(destruct_wq);

        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 (netif_is_bond_master(dev))
                        return NOTIFY_DONE;
                if  (!dev->tlsdev_ops ||
                     !dev->tlsdev_ops->tls_dev_add ||
                     !dev->tlsdev_ops->tls_dev_del)
                        return NOTIFY_BAD;
                if ((dev->features & NETIF_F_HW_TLS_RX) &&
                    !dev->tlsdev_ops->tls_dev_resync)
                        return NOTIFY_BAD;

                return NOTIFY_DONE;
        case NETDEV_DOWN:
                return tls_device_down(dev);
        }
        return NOTIFY_DONE;
}

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

int __init tls_device_init(void)
{
        int err;

        dummy_page = alloc_page(GFP_KERNEL);
        if (!dummy_page)
                return -ENOMEM;

        destruct_wq = alloc_workqueue("ktls_device_destruct", WQ_PERCPU, 0);
        if (!destruct_wq) {
                err = -ENOMEM;
                goto err_free_dummy;
        }

        err = register_netdevice_notifier(&tls_dev_notifier);
        if (err)
                goto err_destroy_wq;

        return 0;

err_destroy_wq:
        destroy_workqueue(destruct_wq);
err_free_dummy:
        put_page(dummy_page);
        return err;
}

void __exit tls_device_cleanup(void)
{
        unregister_netdevice_notifier(&tls_dev_notifier);
        destroy_workqueue(destruct_wq);
        clean_acked_data_flush();
        put_page(dummy_page);
}