/*      $NetBSD: kern_uidinfo.c,v 1.15 2026/01/04 02:09:21 riastradh Exp $      */

/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_uidinfo.c,v 1.15 2026/01/04 02:09:21 riastradh Exp $");

#include <sys/param.h>
#include <sys/types.h>

#include <sys/atomic.h>
#include <sys/cpu.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/uidinfo.h>

static SLIST_HEAD(uihashhead, uidinfo) *uihashtbl;
static u_long           uihash;

#define UIHASH(uid)     (&uihashtbl[(uid) & uihash])

static int
sysctl_kern_uidinfo_cnt(SYSCTLFN_ARGS)
{
        static const struct {
                const char *name;
                u_int value;
        } nv[] = {
#define _MEM(n) { # n, offsetof(struct uidinfo, ui_ ## n) }
                _MEM(proccnt),
                _MEM(lwpcnt),
                _MEM(lockcnt),
                _MEM(semcnt),
                _MEM(sbsize),
#undef _MEM
        };

        for (size_t i = 0; i < __arraycount(nv); i++)
                if (strcmp(nv[i].name, rnode->sysctl_name) == 0) {
                        uint64_t cnt;
                        struct sysctlnode node = *rnode;
                        struct uidinfo *uip;

                        node.sysctl_data = &cnt;
                        uip = uid_find(kauth_cred_geteuid(l->l_cred));

                        *(uint64_t *)node.sysctl_data =
                            *(u_long *)((char *)uip + nv[i].value);

                        return sysctl_lookup(SYSCTLFN_CALL(&node));
                }

        return SET_ERROR(EINVAL);
}

static struct sysctllog *kern_uidinfo_sysctllog;

static void
sysctl_kern_uidinfo_setup(void)
{
        const struct sysctlnode *rnode, *cnode;

        sysctl_createv(&kern_uidinfo_sysctllog, 0, NULL, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "uidinfo",
                       SYSCTL_DESCR("Resource usage per uid"),
                       NULL, 0, NULL, 0,
                       CTL_KERN, CTL_CREATE, CTL_EOL);

        sysctl_createv(&kern_uidinfo_sysctllog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "proccnt",
                       SYSCTL_DESCR("Number of processes for the current user"),
                       sysctl_kern_uidinfo_cnt, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(&kern_uidinfo_sysctllog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "lwpcnt",
                       SYSCTL_DESCR("Number of lwps for the current user"),
                       sysctl_kern_uidinfo_cnt, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(&kern_uidinfo_sysctllog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "lockcnt",
                       SYSCTL_DESCR("Number of locks for the current user"),
                       sysctl_kern_uidinfo_cnt, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(&kern_uidinfo_sysctllog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "semcnt",
                       SYSCTL_DESCR("Number of semaphores used for the current user"),
                       sysctl_kern_uidinfo_cnt, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(&kern_uidinfo_sysctllog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "sbsize",
                       SYSCTL_DESCR("Socket buffers used for the current user"),
                       sysctl_kern_uidinfo_cnt, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
}

static int
uid_stats(struct hashstat_sysctl *hs, bool fill)
{
        struct uidinfo *uip;
        uint64_t chain;

        strlcpy(hs->hash_name, "uihash", sizeof(hs->hash_name));
        strlcpy(hs->hash_desc, "user info (uid->used proc) hash",
            sizeof(hs->hash_desc));
        if (!fill)
                return 0;

        hs->hash_size = uihash + 1;

        for (size_t i = 0; i < hs->hash_size; i++) {
                chain = 0;
                SLIST_FOREACH(uip, &uihashtbl[i], ui_hash) {
                        membar_datadep_consumer();
                        chain++;
                }
                if (chain > 0) {
                        hs->hash_used++;
                        hs->hash_items += chain;
                        if (chain > hs->hash_maxchain)
                                hs->hash_maxchain = chain;
                }
        }

        return 0;
}

void
uid_init(void)
{

        /*
         * In case of MP system, SLIST_FOREACH would force a cache line
         * write-back for every modified 'uidinfo', thus we try to keep the
         * lists short.
         */
        const u_int uihash_sz = (maxcpus > 1 ? 1024 : 64);

        uihashtbl = hashinit(uihash_sz, HASH_SLIST, true, &uihash);

        /*
         * Ensure that uid 0 is always in the user hash table, as
         * sbreserve() expects it available from interrupt context.
         */
        (void)uid_find(0);
        sysctl_kern_uidinfo_setup();
        hashstat_register("uihash", uid_stats);
}

struct uidinfo *
uid_find(uid_t uid)
{
        struct uidinfo *uip, *uip_first, *newuip;
        struct uihashhead *uipp;

        uipp = UIHASH(uid);
        newuip = NULL;

        /*
         * To make insertion atomic, abstraction of SLIST will be violated.
         */
        uip_first = uipp->slh_first;
 again:
        SLIST_FOREACH(uip, uipp, ui_hash) {
                membar_datadep_consumer();
                if (uip->ui_uid != uid)
                        continue;
                if (newuip != NULL)
                        kmem_free(newuip, sizeof(*newuip));
                return uip;
        }
        if (newuip == NULL)
                newuip = kmem_zalloc(sizeof(*newuip), KM_SLEEP);
        newuip->ui_uid = uid;

        /*
         * If atomic insert is unsuccessful, another thread might be
         * allocated this 'uid', thus full re-check is needed.
         */
        newuip->ui_hash.sle_next = uip_first;
        membar_producer();
        uip = atomic_cas_ptr(&uipp->slh_first, uip_first, newuip);
        if (uip != uip_first) {
                uip_first = uip;
                goto again;
        }

        return newuip;
}

/*
 * Change the count associated with number of processes
 * a given user is using.
 */
int
chgproccnt(uid_t uid, int diff)
{
        struct uidinfo *uip;
        long proccnt;

        uip = uid_find(uid);
        proccnt = atomic_add_long_nv(&uip->ui_proccnt, diff);
        KASSERTMSG(proccnt >= 0, "uid=%d diff=%d proccnt=%ld",
            uid, diff, proccnt);
        return proccnt;
}

/*
 * Change the count associated with number of lwps
 * a given user is using.
 */
int
chglwpcnt(uid_t uid, int diff)
{
        struct uidinfo *uip;
        long lwpcnt;

        uip = uid_find(uid);
        lwpcnt = atomic_add_long_nv(&uip->ui_lwpcnt, diff);
        KASSERTMSG(lwpcnt >= 0, "uid=%d diff=%d lwpcnt=%ld",
            uid, diff, lwpcnt);
        return lwpcnt;
}

/*
 * Change the count associated with number of semaphores
 * a given user is using.
 */
int
chgsemcnt(uid_t uid, int diff)
{
        struct uidinfo *uip;
        long semcnt;

        uip = uid_find(uid);
        semcnt = atomic_add_long_nv(&uip->ui_semcnt, diff);
        KASSERTMSG(semcnt >= 0, "uid=%d diff=%d semcnt=%ld",
            uid, diff, semcnt);
        return semcnt;
}

int
chgsbsize(struct uidinfo *uip, u_long *hiwat, u_long to, rlim_t xmax)
{
        rlim_t nsb;
        const long diff = to - *hiwat;

        nsb = (rlim_t)atomic_add_long_nv((long *)&uip->ui_sbsize, diff);
        if (diff > 0 && nsb > xmax) {
                atomic_add_long((long *)&uip->ui_sbsize, -diff);
                return 0;
        }
        *hiwat = to;
        return 1;
}