/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2009 Robert N. M. Watson
 * Copyright (c) 2009 Bjoern A. Zeeb <bz@FreeBSD.org>
 * 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 AUTHOR 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 AUTHOR 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>

#define _WANT_PRISON
#define _WANT_UCRED
#define _WANT_VNET

#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <sys/_task.h>
#include <sys/jail.h>
#include <sys/proc.h>
#include <sys/types.h>

#include <stdbool.h>
#include <net/vnet.h>

#include <kvm.h>
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>

#include "kvm_private.h"

/*
 * Set up libkvm to handle virtual network stack symbols by selecting a
 * starting pid.
 */
int
_kvm_vnet_selectpid(kvm_t *kd, pid_t pid)
{
        struct proc proc;
        struct ucred cred;
        struct prison prison;
        struct vnet vnet;
        struct kvm_nlist nl[] = {
                /*
                 * Note: kvm_nlist strips the first '_' so add an extra one
                 * here to __{start,stop}_set_vnet.
                 */
#define NLIST_START_VNET        0
                { .n_name = "___start_" VNET_SETNAME },
#define NLIST_STOP_VNET         1
                { .n_name = "___stop_" VNET_SETNAME },
#define NLIST_VNET_HEAD         2
                { .n_name = "vnet_head" },
#define NLIST_ALLPROC           3
                { .n_name = "allproc" },
#define NLIST_DUMPTID           4
                { .n_name = "dumptid" },
#define NLIST_PROC0             5
                { .n_name = "proc0" },
                { .n_name = NULL },
        };
        uintptr_t procp, credp;
#define VMCORE_VNET_OF_PROC0
#ifndef VMCORE_VNET_OF_PROC0
        struct thread td;
        uintptr_t tdp;
#endif
        lwpid_t dumptid;

        /*
         * XXX: This only works for native kernels for now.
         */
        if (!kvm_native(kd))
                return (-1);

        /*
         * Locate and cache locations of important symbols
         * using the internal version of _kvm_nlist, turning
         * off initialization to avoid recursion in case of
         * unresolveable symbols.
         */
        if (_kvm_nlist(kd, nl, 0) != 0) {
                /*
                 * XXX-BZ: ___start_/___stop_VNET_SETNAME may fail.
                 * For now do not report an error here as we are called
                 * internally and in `void context' until we merge the
                 * functionality to optionally activate this into programs.
                 * By that time we can properly fail and let the callers
                 * handle the error.
                 */
                /* _kvm_err(kd, kd->program, "%s: no namelist", __func__); */
                return (-1);
        }

        /*
         * Auto-detect if this is a crashdump by reading dumptid.
         */
        dumptid = 0;
        if (nl[NLIST_DUMPTID].n_value) {
                if (kvm_read(kd, nl[NLIST_DUMPTID].n_value, &dumptid,
                    sizeof(dumptid)) != sizeof(dumptid)) {
                        _kvm_err(kd, kd->program, "%s: dumptid", __func__);
                        return (-1);
                }
        }

        /*
         * First, find the process for this pid.  If we are working on a
         * dump, either locate the thread dumptid is referring to or proc0.
         * Based on either, take the address of the ucred.
         */
        credp = 0;

        procp = nl[NLIST_ALLPROC].n_value;
#ifdef VMCORE_VNET_OF_PROC0
        if (dumptid > 0) {
                procp = nl[NLIST_PROC0].n_value;
                pid = 0;
        }
#endif
        while (procp != 0) {
                if (kvm_read(kd, procp, &proc, sizeof(proc)) != sizeof(proc)) {
                        _kvm_err(kd, kd->program, "%s: proc", __func__);
                        return (-1);
                }
#ifndef VMCORE_VNET_OF_PROC0
                if (dumptid > 0) {
                        tdp = (uintptr_t)TAILQ_FIRST(&proc.p_threads);
                        while (tdp != 0) {
                                if (kvm_read(kd, tdp, &td, sizeof(td)) !=
                                    sizeof(td)) {
                                        _kvm_err(kd, kd->program, "%s: thread",
                                            __func__);
                                        return (-1);
                                }
                                if (td.td_tid == dumptid) {
                                        credp = (uintptr_t)td.td_ucred;
                                        break;
                                }
                                tdp = (uintptr_t)TAILQ_NEXT(&td, td_plist);
                        }
                } else
#endif
                if (proc.p_pid == pid)
                        credp = (uintptr_t)proc.p_ucred;
                if (credp != 0)
                        break;
                procp = (uintptr_t)LIST_NEXT(&proc, p_list);
        }
        if (credp == 0) {
                _kvm_err(kd, kd->program, "%s: pid/tid not found", __func__);
                return (-1);
        }
        if (kvm_read(kd, (uintptr_t)credp, &cred, sizeof(cred)) !=
            sizeof(cred)) {
                _kvm_err(kd, kd->program, "%s: cred", __func__);
                return (-1);
        }
        if (cred.cr_prison == NULL) {
                _kvm_err(kd, kd->program, "%s: no jail", __func__);
                return (-1);
        }
        if (kvm_read(kd, (uintptr_t)cred.cr_prison, &prison, sizeof(prison)) !=
            sizeof(prison)) {
                _kvm_err(kd, kd->program, "%s: prison", __func__);
                return (-1);
        }
        if (prison.pr_vnet == NULL) {
                _kvm_err(kd, kd->program, "%s: no vnet", __func__);
                return (-1);
        }
        if (kvm_read(kd, (uintptr_t)prison.pr_vnet, &vnet, sizeof(vnet)) !=
            sizeof(vnet)) {
                _kvm_err(kd, kd->program, "%s: vnet", __func__);
                return (-1);
        }
        if (vnet.vnet_magic_n != VNET_MAGIC_N) {
                _kvm_err(kd, kd->program, "%s: invalid vnet magic#", __func__);
                return (-1);
        }
        kd->vnet_initialized = 1;
        kd->vnet_start = nl[NLIST_START_VNET].n_value;
        kd->vnet_stop = nl[NLIST_STOP_VNET].n_value;
        kd->vnet_current = (uintptr_t)prison.pr_vnet;
        kd->vnet_base = vnet.vnet_data_base;
        return (0);
}

/*
 * Check whether the vnet module has been initialized successfully
 * or not, initialize it if permitted.
 */
int
_kvm_vnet_initialized(kvm_t *kd, int intialize)
{

        if (kd->vnet_initialized || !intialize)
                return (kd->vnet_initialized);

        (void) _kvm_vnet_selectpid(kd, getpid());

        return (kd->vnet_initialized);
}

/*
 * Check whether the value is within the vnet symbol range and
 * only if so adjust the offset relative to the current base.
 */
kvaddr_t
_kvm_vnet_validaddr(kvm_t *kd, kvaddr_t value)
{

        if (value == 0)
                return (value);

        if (!kd->vnet_initialized)
                return (value);

        if (value < kd->vnet_start || value >= kd->vnet_stop)
                return (value);

        return (kd->vnet_base + value);
}