/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2005-2011 Pawel Jakub Dawidek <pawel@dawidek.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/linker.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bio.h>
#include <sys/sysctl.h>
#include <sys/kthread.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/vnode.h>

#include <vm/uma.h>

#include <geom/geom.h>
#include <geom/geom_dbg.h>
#include <geom/eli/g_eli.h>
#include <geom/eli/pkcs5v2.h>

/*
 * Code paths:
 * BIO_READ:
 *      g_eli_start -> g_eli_crypto_read -> g_io_request -> g_eli_read_done -> g_eli_crypto_run -> g_eli_crypto_read_done -> g_io_deliver
 * BIO_WRITE:
 *      g_eli_start -> g_eli_crypto_run -> g_eli_crypto_write_done -> g_io_request -> g_eli_write_done -> g_io_deliver
 */

/*
 * Copy data from a (potentially unmapped) bio to a kernelspace buffer.
 *
 * The buffer must have at least as much room as bp->bio_length.
 */
static void
g_eli_bio_copyin(struct bio *bp, void *kaddr)
{
        struct uio uio;
        struct iovec iov[1];

        iov[0].iov_base = kaddr;
        iov[0].iov_len = bp->bio_length;
        uio.uio_iov = iov;
        uio.uio_iovcnt = 1;
        uio.uio_offset = 0;
        uio.uio_resid = bp->bio_length;
        uio.uio_segflg = UIO_SYSSPACE;
        uio.uio_rw = UIO_READ;
        uiomove_fromphys(bp->bio_ma, bp->bio_ma_offset, bp->bio_length, &uio);
}

/*
 * The function is called after we read and decrypt data.
 *
 * g_eli_start -> g_eli_crypto_read -> g_io_request -> g_eli_read_done -> g_eli_crypto_run -> G_ELI_CRYPTO_READ_DONE -> g_io_deliver
 */
static int
g_eli_crypto_read_done(struct cryptop *crp)
{
        struct g_eli_softc *sc;
        struct bio *bp;

        if (crp->crp_etype == EAGAIN) {
                if (g_eli_crypto_rerun(crp) == 0)
                        return (0);
        }
        bp = (struct bio *)crp->crp_opaque;
        bp->bio_inbed++;
        if (crp->crp_etype == 0) {
                G_ELI_DEBUG(3, "Crypto READ request done (%d/%d).",
                    bp->bio_inbed, bp->bio_children);
                bp->bio_completed += crp->crp_payload_length;
        } else {
                G_ELI_DEBUG(1, "Crypto READ request failed (%d/%d) error=%d.",
                    bp->bio_inbed, bp->bio_children, crp->crp_etype);
                if (bp->bio_error == 0)
                        bp->bio_error = crp->crp_etype;
        }
        sc = bp->bio_to->geom->softc;
        if (sc != NULL && crp->crp_cipher_key != NULL)
                g_eli_key_drop(sc, __DECONST(void *, crp->crp_cipher_key));
        crypto_freereq(crp);
        /*
         * Do we have all sectors already?
         */
        if (bp->bio_inbed < bp->bio_children)
                return (0);

        if (bp->bio_error != 0) {
                G_ELI_LOGREQ(0, bp, "Crypto READ request failed (error=%d).",
                    bp->bio_error);
                bp->bio_completed = 0;
        }
        /*
         * Read is finished, send it up.
         */
        g_io_deliver(bp, bp->bio_error);
        if (sc != NULL)
                atomic_subtract_int(&sc->sc_inflight, 1);
        return (0);
}

/*
 * The function is called after data encryption.
 *
 * g_eli_start -> g_eli_crypto_run -> G_ELI_CRYPTO_WRITE_DONE -> g_io_request -> g_eli_write_done -> g_io_deliver
 */
static int
g_eli_crypto_write_done(struct cryptop *crp)
{
        struct g_eli_softc *sc;
        struct g_geom *gp;
        struct g_consumer *cp;
        struct bio *bp, *cbp;

        if (crp->crp_etype == EAGAIN) {
                if (g_eli_crypto_rerun(crp) == 0)
                        return (0);
        }
        bp = (struct bio *)crp->crp_opaque;
        bp->bio_inbed++;
        if (crp->crp_etype == 0) {
                G_ELI_DEBUG(3, "Crypto WRITE request done (%d/%d).",
                    bp->bio_inbed, bp->bio_children);
        } else {
                G_ELI_DEBUG(1, "Crypto WRITE request failed (%d/%d) error=%d.",
                    bp->bio_inbed, bp->bio_children, crp->crp_etype);
                if (bp->bio_error == 0)
                        bp->bio_error = crp->crp_etype;
        }
        gp = bp->bio_to->geom;
        sc = gp->softc;
        if (crp->crp_cipher_key != NULL)
                g_eli_key_drop(sc, __DECONST(void *, crp->crp_cipher_key));
        crypto_freereq(crp);
        /*
         * All sectors are already encrypted?
         */
        if (bp->bio_inbed < bp->bio_children)
                return (0);
        bp->bio_inbed = 0;
        bp->bio_children = 1;
        cbp = bp->bio_driver1;
        bp->bio_driver1 = NULL;
        if (bp->bio_error != 0) {
                G_ELI_LOGREQ(0, bp, "Crypto WRITE request failed (error=%d).",
                    bp->bio_error);
                g_eli_free_data(bp);
                g_destroy_bio(cbp);
                g_io_deliver(bp, bp->bio_error);
                atomic_subtract_int(&sc->sc_inflight, 1);
                return (0);
        }
        cbp->bio_data = bp->bio_driver2;
        /* 
         * Clear BIO_UNMAPPED, which was inherited from where we cloned the bio
         * in g_eli_start, because we manually set bio_data
         */
        cbp->bio_flags &= ~BIO_UNMAPPED;
        cbp->bio_done = g_eli_write_done;
        cp = LIST_FIRST(&gp->consumer);
        cbp->bio_to = cp->provider;
        G_ELI_LOGREQ(2, cbp, "Sending request.");
        /*
         * Send encrypted data to the provider.
         */
        g_io_request(cbp, cp);
        return (0);
}

/*
 * The function is called to read encrypted data.
 *
 * g_eli_start -> G_ELI_CRYPTO_READ -> g_io_request -> g_eli_read_done -> g_eli_crypto_run -> g_eli_crypto_read_done -> g_io_deliver
 */
void
g_eli_crypto_read(struct g_eli_softc *sc, struct bio *bp, boolean_t fromworker)
{
        struct g_consumer *cp;
        struct bio *cbp;

        if (!fromworker) {
                /*
                 * We are not called from the worker thread, so check if
                 * device is suspended.
                 */
                mtx_lock(&sc->sc_queue_mtx);
                if (sc->sc_flags & G_ELI_FLAG_SUSPEND) {
                        /*
                         * If device is suspended, we place the request onto
                         * the queue, so it can be handled after resume.
                         */
                        G_ELI_DEBUG(0, "device suspended, move onto queue");
                        bioq_insert_tail(&sc->sc_queue, bp);
                        mtx_unlock(&sc->sc_queue_mtx);
                        wakeup(sc);
                        return;
                }
                atomic_add_int(&sc->sc_inflight, 1);
                mtx_unlock(&sc->sc_queue_mtx);
        }
        G_ELI_SETWORKER(bp->bio_pflags, 0);
        bp->bio_driver2 = NULL;
        cbp = bp->bio_driver1;
        cbp->bio_done = g_eli_read_done;
        cp = LIST_FIRST(&sc->sc_geom->consumer);
        cbp->bio_to = cp->provider;
        G_ELI_LOGREQ(2, cbp, "Sending request.");
        /*
         * Read encrypted data from provider.
         */
        g_io_request(cbp, cp);
}

/*
 * This is the main function responsible for cryptography (ie. communication
 * with crypto(9) subsystem).
 *
 * BIO_READ:
 *      g_eli_start -> g_eli_crypto_read -> g_io_request -> g_eli_read_done -> G_ELI_CRYPTO_RUN -> g_eli_crypto_read_done -> g_io_deliver
 * BIO_WRITE:
 *      g_eli_start -> G_ELI_CRYPTO_RUN -> g_eli_crypto_write_done -> g_io_request -> g_eli_write_done -> g_io_deliver
 */
void
g_eli_crypto_run(struct g_eli_worker *wr, struct bio *bp)
{
        struct g_eli_softc *sc;
        struct cryptopq crpq;
        struct cryptop *crp;
        vm_page_t *pages;
        u_int i, nsec, secsize;
        off_t dstoff;
        u_char *data = NULL;
        int error __diagused, pages_offset;
        bool batch;

        G_ELI_LOGREQ(3, bp, "%s", __func__);

        G_ELI_SETWORKER(bp->bio_pflags, wr->w_number);
        sc = wr->w_softc;
        secsize = LIST_FIRST(&sc->sc_geom->provider)->sectorsize;
        nsec = bp->bio_length / secsize;

        bp->bio_inbed = 0;
        bp->bio_children = nsec;

        /*
         * If we write the data we cannot destroy current bio_data content,
         * so we need to allocate more memory for encrypted data.
         */
        if (bp->bio_cmd == BIO_WRITE) {
                if (!g_eli_alloc_data(bp, bp->bio_length)) {
                        G_ELI_LOGREQ(0, bp, "Crypto request failed (ENOMEM).");
                        if (bp->bio_driver1 != NULL) {
                                g_destroy_bio(bp->bio_driver1);
                                bp->bio_driver1 = NULL;
                        }
                        bp->bio_error = ENOMEM;
                        g_io_deliver(bp, bp->bio_error);
                        if (sc != NULL)
                                atomic_subtract_int(&sc->sc_inflight, 1);
                        return;
                }
                data = bp->bio_driver2;
                /* 
                 * This copy could be eliminated by using crypto's output
                 * buffer, instead of using a single overwriting buffer.
                 */
                if ((bp->bio_flags & BIO_UNMAPPED) != 0)
                        g_eli_bio_copyin(bp, data);
                else
                        bcopy(bp->bio_data, data, bp->bio_length);
        } else {
                if ((bp->bio_flags & BIO_UNMAPPED) != 0) {
                        pages = bp->bio_ma;
                        pages_offset = bp->bio_ma_offset;
                } else {
                        data = bp->bio_data;
                }
        }

        TAILQ_INIT(&crpq);
        batch = atomic_load_int(&g_eli_batch) != 0;

        for (i = 0, dstoff = bp->bio_offset; i < nsec; i++, dstoff += secsize) {
                crp = crypto_getreq(wr->w_sid, M_WAITOK);

                if (data) {
                        crypto_use_buf(crp, data, secsize);
                        data += secsize;
                } else {
                        MPASS(pages != NULL);
                        crypto_use_vmpage(crp, pages, secsize, pages_offset);
                        pages_offset += secsize;
                        pages += pages_offset >> PAGE_SHIFT;
                        pages_offset &= PAGE_MASK;
                }
                crp->crp_opaque = (void *)bp;
                if (bp->bio_cmd == BIO_WRITE) {
                        crp->crp_op = CRYPTO_OP_ENCRYPT;
                        crp->crp_callback = g_eli_crypto_write_done;
                } else /* if (bp->bio_cmd == BIO_READ) */ {
                        crp->crp_op = CRYPTO_OP_DECRYPT;
                        crp->crp_callback = g_eli_crypto_read_done;
                }
                crp->crp_flags = CRYPTO_F_CBIFSYNC;
                crp->crp_payload_start = 0;
                crp->crp_payload_length = secsize;
                if ((sc->sc_flags & G_ELI_FLAG_SINGLE_KEY) == 0) {
                        crp->crp_cipher_key = g_eli_key_hold(sc, dstoff,
                            secsize);
                }
                if (g_eli_ivlen(sc->sc_ealgo) != 0) {
                        crp->crp_flags |= CRYPTO_F_IV_SEPARATE;
                        g_eli_crypto_ivgen(sc, dstoff, crp->crp_iv,
                            sizeof(crp->crp_iv));
                }

                if (batch) {
                        TAILQ_INSERT_TAIL(&crpq, crp, crp_next);
                } else {
                        error = crypto_dispatch(crp);
                        KASSERT(error == 0,
                            ("crypto_dispatch() failed (error=%d)", error));
                }
        }

        if (batch)
                crypto_dispatch_batch(&crpq, 0);
}