/*      $NetBSD: kern_uidinfo.c,v 1.13 2021/12/28 13:28:24 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 1.13 2021/12/28 13:28:24 riastradh Exp $");

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

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