/*      $NetBSD: sys_module.c,v 1.30 2022/05/24 06:20:05 andvar Exp $   */

/*-
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * System calls relating to loadable modules.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_module.c,v 1.30 2022/05/24 06:20:05 andvar Exp $");

#ifdef _KERNEL_OPT
#include "opt_modular.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/kobj.h>
#include <sys/module.h>
#include <sys/syscall.h>
#include <sys/syscallargs.h>
#include <sys/compat_stub.h>

/*
 * Arbitrary limit to avoid DoS for excessive memory allocation.
 */
#define MAXPROPSLEN     4096

int
handle_modctl_load(const char *ml_filename, int ml_flags, const char *ml_props,
    size_t ml_propslen)
{
        char *path;
        char *props;
        int error;
        prop_dictionary_t dict;
        size_t propslen = 0;

        if ((ml_props != NULL && ml_propslen == 0) ||
            (ml_props == NULL && ml_propslen > 0)) {
                return EINVAL;
        }

        path = PNBUF_GET();
        error = copyinstr(ml_filename, path, MAXPATHLEN, NULL);
        if (error != 0)
                goto out1;

        if (ml_props != NULL) {
                if (ml_propslen > MAXPROPSLEN) {
                        error = ENOMEM;
                        goto out1;
                }
                propslen = ml_propslen + 1;

                props = kmem_alloc(propslen, KM_SLEEP);
                error = copyinstr(ml_props, props, propslen, NULL);
                if (error != 0)
                        goto out2;

                dict = prop_dictionary_internalize(props);
                if (dict == NULL) {
                        error = EINVAL;
                        goto out2;
                }
        } else {
                dict = NULL;
                props = NULL;
        }

        error = module_load(path, ml_flags, dict, MODULE_CLASS_ANY);

        if (dict != NULL) {
                prop_object_release(dict);
        }

out2:
        if (props != NULL) {
                kmem_free(props, propslen);
        }
out1:
        PNBUF_PUT(path);
        return error;
}

static int
handle_modctl_stat(struct iovec *iov, void *arg)
{
        int ms_cnt;
        modstat_t *ms, *mso;
        size_t ms_len;
        char *req, *reqo;
        size_t req_len;
        char *out_p;
        size_t out_s;

        modinfo_t *mi;
        module_t *mod;
        vaddr_t addr;
        size_t size;
        size_t used;
        int off;
        int error;
        bool stataddr;

        /* If not privileged, don't expose kernel addresses. */
        error = kauth_authorize_process(kauth_cred_get(), KAUTH_PROCESS_CANSEE,
            curproc, KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_KPTR), NULL, NULL);
        stataddr = (error == 0);

        kernconfig_lock();
        ms_cnt = 0;
        req_len = 1;

        /*
         * Count up the number of modstat_t needed, and total size of
         * require_module lists on both active and built-in lists
         */
        TAILQ_FOREACH(mod, &module_list, mod_chain) {
                ms_cnt++;
                mi = mod->mod_info;
                if (mi->mi_required != NULL) {
                        req_len += strlen(mi->mi_required) + 1;
                }
        }
        TAILQ_FOREACH(mod, &module_builtins, mod_chain) {
                ms_cnt++;
                mi = mod->mod_info;
                if (mi->mi_required != NULL) {
                        req_len += strlen(mi->mi_required) + 1;
                }
        }

        /* Allocate internal buffers to hold all the output data */
        ms_len = ms_cnt * sizeof(modstat_t);
        ms = kmem_zalloc(ms_len, KM_SLEEP);
        req = kmem_zalloc(req_len, KM_SLEEP);

        mso = ms;
        reqo = req++;
        off = 1;

        /*
         * Load data into our internal buffers for both active and
         * built-in module lists
         */
        TAILQ_FOREACH(mod, &module_list, mod_chain) {
                mi = mod->mod_info;
                strlcpy(ms->ms_name, mi->mi_name, sizeof(ms->ms_name));
                if (mi->mi_required != NULL) {
                        ms->ms_reqoffset = off;
                        used = strlcpy(req,  mi->mi_required, req_len - off);
                        KASSERTMSG(used < req_len - off, "reqlist grew!");
                        off += used + 1;
                        req += used + 1;
                } else
                        ms->ms_reqoffset = 0;
                if (mod->mod_kobj != NULL && stataddr) {
                        kobj_stat(mod->mod_kobj, &addr, &size);
                        ms->ms_addr = addr;
                        ms->ms_size = size;
                }
                ms->ms_class = mi->mi_class;
                ms->ms_refcnt = mod->mod_refcnt;
                ms->ms_source = mod->mod_source;
                ms->ms_flags = mod->mod_flags;
                ms++;
        }
        TAILQ_FOREACH(mod, &module_builtins, mod_chain) {
                mi = mod->mod_info;
                strlcpy(ms->ms_name, mi->mi_name, sizeof(ms->ms_name));
                if (mi->mi_required != NULL) {
                        ms->ms_reqoffset = off;
                        used = strlcpy(req,  mi->mi_required, req_len - off);
                        KASSERTMSG(used < req_len - off, "reqlist grew!");
                        off += used + 1;
                        req += used + 1;
                } else
                        ms->ms_reqoffset = 0;
                if (mod->mod_kobj != NULL && stataddr) {
                        kobj_stat(mod->mod_kobj, &addr, &size);
                        ms->ms_addr = addr;
                        ms->ms_size = size;
                }
                ms->ms_class = mi->mi_class;
                ms->ms_refcnt = -1;
                KASSERT(mod->mod_source == MODULE_SOURCE_KERNEL);
                ms->ms_source = mod->mod_source;
                ms++;
        }
        kernconfig_unlock();

        /*
         * Now copyout our internal buffers back to userland
         */
        out_p = iov->iov_base;
        out_s = iov->iov_len;
        size = sizeof(ms_cnt);

        /* Copy out the count of modstat_t */
        if (out_s) {
                size = uimin(sizeof(ms_cnt), out_s);
                error = copyout(&ms_cnt, out_p, size);
                out_p += size;
                out_s -= size;
        }
        /* Copy out the modstat_t array */
        if (out_s && error == 0) {
                size = uimin(ms_len, out_s);
                error = copyout(mso, out_p, size);
                out_p += size;
                out_s -= size;
        }
        /* Copy out the "required" strings */
        if (out_s && error == 0) {
                size = uimin(req_len, out_s);
                error = copyout(reqo, out_p, size);
                out_p += size;
                out_s -= size;
        }
        kmem_free(mso, ms_len);
        kmem_free(reqo, req_len);

        /* Finally, update the userland copy of the iovec's length */
        if (error == 0) {
                iov->iov_len = ms_len + req_len + sizeof(ms_cnt);
                error = copyout(iov, arg, sizeof(*iov));
        }

        return error;
}

int
sys_modctl(struct lwp *l, const struct sys_modctl_args *uap,
           register_t *retval)
{
        /* {
                syscallarg(int)         cmd;
                syscallarg(void *)      arg;
        } */
        char buf[MAXMODNAME];
        struct iovec iov;
        modctl_load_t ml;
        int error;
        void *arg;
#ifdef MODULAR
        uintptr_t loadtype;
#endif

        arg = SCARG(uap, arg);

        switch (SCARG(uap, cmd)) {
        case MODCTL_LOAD:
                error = copyin(arg, &ml, sizeof(ml));
                if (error != 0)
                        break;
                error = handle_modctl_load(ml.ml_filename, ml.ml_flags,
                    ml.ml_props, ml.ml_propslen);
                break;

        case MODCTL_UNLOAD:
                error = copyinstr(arg, buf, sizeof(buf), NULL);
                if (error == 0) {
                        error = module_unload(buf);
                }
                break;

        case MODCTL_STAT:
                error = copyin(arg, &iov, sizeof(iov));
                if (error != 0) {
                        break;
                }
                error = handle_modctl_stat(&iov, arg);
                break;

        case MODCTL_EXISTS:
#ifndef MODULAR
                error = ENOSYS;
#else
                loadtype = (uintptr_t)arg;
                switch (loadtype) {     /* 0 = modload, 1 = autoload */
                case 0:                 /* FALLTHROUGH */
                case 1:
                        error = kauth_authorize_system(kauth_cred_get(),
                             KAUTH_SYSTEM_MODULE, 0,
                             (void *)(uintptr_t)MODCTL_LOAD,
                             (void *)loadtype, NULL);
                        break;
                default:
                        error = EINVAL;
                        break;
                }
#endif
                break;

        default:
                (void)module_autoload("compat_80", MODULE_CLASS_EXEC);
                MODULE_HOOK_CALL(compat_modstat_80_hook,
                    (SCARG(uap, cmd), &iov, arg), enosys(), error);
                if (error == ENOSYS)
                        error = EINVAL;
                break;
        }

        return error;
}