/*-
 * Copyright (c) 2021-2022 Juniper Networks
 *
 * This software was developed by Mitchell Horne <mhorne@FreeBSD.org>
 * under sponsorship from Juniper Networks and Klara Systems.
 *
 * 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 AUTHOR ``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 AUTHOR 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/conf.h>
#include <sys/caprights.h>
#include <sys/disk.h>
#include <sys/eventhandler.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/kerneldump.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>

#include <machine/pcb.h>
#include <machine/vmparam.h>

static dumper_start_t vnode_dumper_start;
static dumper_t vnode_dump;
static dumper_hdr_t vnode_write_headers;

static struct sx livedump_sx;
SX_SYSINIT(livedump, &livedump_sx, "Livedump sx");

/*
 * Invoke a live minidump on the system.
 */
int
livedump_start(int fd, int flags, uint8_t compression)
{
#if MINIDUMP_PAGE_TRACKING == 1
        struct file *fp;
        struct vnode *vp;
        int error;

        error = priv_check(curthread, PRIV_KMEM_READ);
        if (error != 0)
                return (error);

        if (flags != 0)
                return (EINVAL);

        error = getvnode(curthread, fd, &cap_write_rights, &fp);
        if (error != 0)
                return (error);
        vp = fp->f_vnode;

        if ((fp->f_flag & FWRITE) == 0) {
                error = EBADF;
                goto drop;
        }
        error = livedump_start_vnode(vp, flags, compression);
        if (error != 0)
                goto drop;
drop:
        fdrop(fp, curthread);
        return (error);
#else
        return (EOPNOTSUPP);
#endif /* MINIDUMP_PAGE_TRACKING == 1 */
}

int
livedump_start_vnode(struct vnode *vp, int flags, uint8_t compression)
{
#if MINIDUMP_PAGE_TRACKING == 1
        struct dumperinfo di, *livedi;
        struct diocskerneldump_arg kda;
        void *rl_cookie;
        int error;

        /* Set up a new dumper. */
        bzero(&di, sizeof(di));
        di.dumper_start = vnode_dumper_start;
        di.dumper = vnode_dump;
        di.dumper_hdr = vnode_write_headers;
        di.blocksize = PAGE_SIZE; /* Arbitrary. */
        di.maxiosize = MAXDUMPPGS * PAGE_SIZE;

        bzero(&kda, sizeof(kda));
        kda.kda_compression = compression;
        error = dumper_create(&di, "livedump", &kda, &livedi);
        if (error != 0)
                return (error);

        /* Only allow one livedump to proceed at a time. */
        if (sx_try_xlock(&livedump_sx) == 0) {
                dumper_destroy(livedi);
                error = EBUSY;
                return (error);
        }

        /* To be used by the callback functions. */
        livedi->priv = vp;

        /* Lock the entire file range and vnode. */
        rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);

        EVENTHANDLER_INVOKE(livedumper_start, &error);
        if (error != 0)
                goto out;

        curthread->td_pflags2 |= TDP2_SAN_QUIET;
        dump_savectx();
        error = minidumpsys(livedi, true);
        curthread->td_pflags2 &= ~TDP2_SAN_QUIET;

        EVENTHANDLER_INVOKE(livedumper_finish);
out:
        VOP_UNLOCK(vp);
        vn_rangelock_unlock(vp, rl_cookie);
        sx_xunlock(&livedump_sx);
        dumper_destroy(livedi);
        return (error);
#else
        return (EOPNOTSUPP);
#endif /* MINIDUMP_PAGE_TRACKING == 1 */
}

int
vnode_dumper_start(struct dumperinfo *di, void *key, uint32_t keysize)
{

        /* Always begin with an offset of zero. */
        di->dumpoff = 0;

        KASSERT(keysize == 0, ("encryption not supported for livedumps"));
        return (0);
}

/*
 * Callback from dumpsys() to dump a chunk of memory.
 *
 * Parameters:
 *      arg      Opaque private pointer to vnode
 *      virtual  Virtual address (where to read the data from)
 *      offset   Offset from start of core file
 *      length   Data length
 *
 * Return value:
 *      0 on success
 *      errno on error
 */
int
vnode_dump(void *arg, void *virtual, off_t offset, size_t length)
{
        struct vnode *vp;
        int error = 0;

        vp = arg;
        MPASS(vp != NULL);
        ASSERT_VOP_LOCKED(vp, __func__);

        EVENTHANDLER_INVOKE(livedumper_dump, virtual, offset, length, &error);
        if (error != 0)
                return (error);

        /* Done? */
        if (virtual == NULL)
                return (0);

        error = vn_rdwr(UIO_WRITE, vp, virtual, length, offset, UIO_SYSSPACE,
            IO_NODELOCKED, curthread->td_ucred, NOCRED, NULL, curthread);
        if (error != 0)
                uprintf("%s: error writing livedump block at offset %jx: %d\n",
                    __func__, (uintmax_t)offset, error);
        return (error);
}

/*
 * Callback from dumpsys() to write out the dump header, placed at the end.
 */
int
vnode_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
{
        struct vnode *vp;
        int error;
        off_t offset;

        vp = di->priv;
        MPASS(vp != NULL);
        ASSERT_VOP_LOCKED(vp, __func__);

        /* Compensate for compression/encryption adjustment of dumpoff. */
        offset = roundup2(di->dumpoff, di->blocksize);

        /* Write the kernel dump header to the end of the file. */
        error = vn_rdwr(UIO_WRITE, vp, kdh, sizeof(*kdh), offset,
            UIO_SYSSPACE, IO_NODELOCKED, curthread->td_ucred, NOCRED, NULL,
            curthread);
        if (error != 0)
                uprintf("%s: error writing livedump header: %d\n", __func__,
                    error);
        return (error);
}