/* 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)
{
        struct tls_offload_context *offload_ctx = tls_offload_ctx(ctx);

        kfree(offload_ctx);
        kfree(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) {
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_TX);
                        dev_put(netdev);
                }

                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 *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 *ctx;
        u64 deleted_records = 0;
        unsigned long flags;

        if (!tls_ctx)
                return;

        ctx = tls_offload_ctx(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.
 */
void tls_device_sk_destruct(struct sock *sk)
{
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_offload_context *ctx = tls_offload_ctx(tls_ctx);

        if (ctx->open_record)
                destroy_record(ctx->open_record);

        delete_all_records(ctx);
        crypto_free_aead(ctx->aead_send);
        ctx->sk_destruct(sk);
        clean_acked_data_disable(inet_csk(sk));

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

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 *offload_ctx,
                           struct tls_record_info *record,
                           struct page_frag *pfrag,
                           int flags,
                           unsigned char record_type)
{
        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 - ctx->tx.prepend_size,
                         record_type);

        /* 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, ctx->tx.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;
        set_bit(TLS_PENDING_CLOSED_RECORD, &ctx->flags);
        tls_advance_record_sn(sk, &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 *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 *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_offload_context *ctx = tls_offload_ctx(tls_ctx);
        int tls_push_record_flags = flags | MSG_SENDPAGE_NOTLAST;
        int more = flags & (MSG_SENDPAGE_NOTLAST | MSG_MORE);
        struct tls_record_info *record = ctx->open_record;
        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;

        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
        rc = tls_complete_pending_work(sk, tls_ctx, flags, &timeo);
        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 +
                              tls_ctx->tx.prepend_size;
        do {
                rc = tls_do_allocation(sk, ctx, pfrag,
                                       tls_ctx->tx.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 > tls_ctx->tx.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 | ITER_KVEC, &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 *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 | ITER_KVEC, NULL, 0, 0);
        return tls_push_data(sk, &msg_iter, 0, flags, TLS_RECORD_TYPE_DATA);
}

int tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
{
        u16 nonce_size, tag_size, iv_size, rec_seq_size;
        struct tls_record_info *start_marker_record;
        struct tls_offload_context *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, GFP_KERNEL);
        if (!offload_ctx) {
                rc = -ENOMEM;
                goto free_marker_record;
        }

        crypto_info = &ctx->crypto_send;
        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;
        }

        ctx->tx.prepend_size = TLS_HEADER_SIZE + nonce_size;
        ctx->tx.tag_size = tag_size;
        ctx->tx.overhead_size = ctx->tx.prepend_size + ctx->tx.tag_size;
        ctx->tx.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);

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

        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;
        offload_ctx->sk_destruct = sk->sk_destruct;

        /* 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;

        refcount_set(&ctx->refcount, 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,
                                             tcp_sk(sk)->write_seq);
        if (rc)
                goto release_netdev;

        ctx->netdev = netdev;

        spin_lock_irq(&tls_device_lock);
        list_add_tail(&ctx->list, &tls_device_list);
        spin_unlock_irq(&tls_device_lock);

        sk->sk_validate_xmit_skb = tls_validate_xmit_skb;
        /* 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_destruct,
                          &tls_device_sk_destruct);
        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;
}

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) {
                netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                TLS_OFFLOAD_CTX_DIR_TX);
                ctx->netdev = NULL;
                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->features & NETIF_F_HW_TLS_TX))
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_REGISTER:
        case NETDEV_FEAT_CHANGE:
                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);
}