/*      $NetBSD: sysv_ipc.c,v 1.43 2024/10/09 16:27:28 christos Exp $   */

/*-
 * Copyright (c) 1998, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum.
 *
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sysv_ipc.c,v 1.43 2024/10/09 16:27:28 christos Exp $");

#ifdef _KERNEL_OPT
#include "opt_sysv.h"
#include "opt_sysvparam.h"
#include "opt_compat_netbsd.h"
#endif

#include <sys/syscall.h>
#include <sys/syscallargs.h>
#include <sys/syscallvar.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/ipc.h>
#ifdef SYSVMSG
#include <sys/msg.h>
#endif
#ifdef SYSVSEM
#include <sys/sem.h>
#endif
#ifdef SYSVSHM
#include <sys/shm.h>
#endif
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>
#include <sys/compat_stub.h>

#include <compat/common/compat_sysv_mod.h>      /* for sysctl routine vector */

/*
 * Values in support of System V compatible shared memory.      XXX
 * (originally located in sys/conf/param.c)
 */
#ifdef SYSVSHM
#if !defined(SHMMAX) && defined(SHMMAXPGS)
#define SHMMAX  SHMMAXPGS       /* shminit() performs a `*= PAGE_SIZE' */
#elif !defined(SHMMAX)
#define SHMMAX 0
#endif
#ifndef SHMMIN
#define SHMMIN  1
#endif
#ifndef SHMMNI
#define SHMMNI  128             /* <64k, see IPCID_TO_IX in ipc.h */
#endif
#ifndef SHMSEG
#define SHMSEG  128
#endif

struct  shminfo shminfo = {
        SHMMAX,
        SHMMIN,
        SHMMNI,
        SHMSEG,
        0
};
#endif

/*
 * Values in support of System V compatible semaphores.
 */
#ifdef SYSVSEM
struct  seminfo seminfo = {
        SEMMAP,         /* # of entries in semaphore map */
        SEMMNI,         /* # of semaphore identifiers */
        SEMMNS,         /* # of semaphores in system */
        SEMMNU,         /* # of undo structures in system */
        SEMMSL,         /* max # of semaphores per id */
        SEMOPM,         /* max # of operations per semop call */
        SEMUME,         /* max # of undo entries per process */
        SEMUSZ,         /* size in bytes of undo structure */
        SEMVMX,         /* semaphore maximum value */
        SEMAEM          /* adjust on exit max value */
};
#endif

/*
 * Values in support of System V compatible messages.
 */
#ifdef SYSVMSG
struct  msginfo msginfo = {
        MSGMAX,         /* max chars in a message */
        MSGMNI,         /* # of message queue identifiers */
        MSGMNB,         /* max chars in a queue */
        MSGTQL,         /* max messages in system */
        MSGSSZ,         /* size of a message segment */
                        /* (must be small power of 2 greater than 4) */
        MSGSEG          /* number of message segments */
};
#endif

MODULE(MODULE_CLASS_EXEC, sysv_ipc, NULL);
 
SYSCTL_SETUP_PROTO(sysctl_ipc_setup);

static const struct syscall_package sysvipc_syscalls[] = {
#if defined(SYSVSHM)
        { SYS___shmctl50, 0, (sy_call_t *)sys___shmctl50 },
        { SYS_shmat, 0, (sy_call_t *)sys_shmat },
        { SYS_shmdt, 0, (sy_call_t *)sys_shmdt },
        { SYS_shmget, 0, (sy_call_t *)sys_shmget },
#endif  /* SYSVSHM */

#if defined(SYSVSEM)
        { SYS_____semctl50, 0, (sy_call_t *)sys_____semctl50 },
        { SYS_semget, 0, (sy_call_t *)sys_semget },
        { SYS_semop, 0, (sy_call_t *)sys_semop },
        { SYS_semconfig, 0, (sy_call_t *)sys_semconfig },
        { SYS_semtimedop, 0, (sy_call_t *)sys_semtimedop },
#endif  /* SYSVSEM */

#if defined(SYSVMSG)
        { SYS___msgctl50, 0, (sy_call_t *)sys___msgctl50 },
        { SYS_msgget, 0, (sy_call_t *)sys_msgget },
        { SYS_msgsnd, 0, (sy_call_t *)sys_msgsnd },
        { SYS_msgrcv, 0, (sy_call_t *)sys_msgrcv },
#endif  /* SYSVMSG */
        { 0, 0, NULL }
};

static int
sysv_ipc_modcmd(modcmd_t cmd, void *arg)
{
        int error = 0;

        switch (cmd) {
        case MODULE_CMD_INIT:
                /* Set up the kauth listener */
                sysvipcinit();

                /* Link the system calls */
                error = syscall_establish(NULL, sysvipc_syscalls);
                if (error) {
                        sysvipcfini();
                        return error;
                }

                /*
                 * Initialize each sub-component, including their
                 * sysctl data
                 */
#ifdef SYSVSHM
                error = shminit();
                if (error != 0)
                        return error;
#endif
#ifdef SYSVSEM
                error = seminit();
                if (error != 0) {
#ifdef SYSVSHM
                        shmfini();
#endif
                        return error;
                }
#endif
#ifdef SYSVMSG
                error = msginit();
                if (error != 0) {
#ifdef SYSVSEM
                        semfini();
#endif
#ifdef SYSVSHM
                        shmfini();
#endif
                        return error;
                }
#endif
                break;
        case MODULE_CMD_FINI:
                /*
                 * Make sure no subcomponents are active.  Each one
                 * tells us if it is busy, and if it was _not_ busy,
                 * we assume it has already done its own clean-up.
                 * So we might need to re-init any components that
                 * are successfully fini'd if we find one that is 
                 * still busy.
                 */
#ifdef SYSVSHM
                if (shmfini()) {
                        return EBUSY;
                }
#endif
#ifdef SYSVSEM
                if (semfini()) {
#ifdef SYSVSHM
                        shminit();
#endif
                        return EBUSY;
                }
#endif
#ifdef SYSVMSG
                if (msgfini()) {
#ifdef SYSVSEM
                        seminit();
#endif
#ifdef SYSVSHM
                        shminit();
#endif
                        return EBUSY;
                }
#endif
                /* Unlink the system calls. */
                error = syscall_disestablish(NULL, sysvipc_syscalls);
                if (error)
                        return error;

                /* Remove the kauth listener */
                sysvipcfini();
                break;
        default:
                return ENOTTY;
        }
        return error;
}

static kauth_listener_t sysvipc_listener = NULL;

static int
sysvipc_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        mode_t mask;
        struct ipc_perm *perm;
        int mode;
        enum kauth_system_req req;

        req = (enum kauth_system_req)(uintptr_t)arg0;

        if (!(action == KAUTH_SYSTEM_SYSVIPC &&
              req == KAUTH_REQ_SYSTEM_SYSVIPC_BYPASS))
                return KAUTH_RESULT_DEFER;

        perm = arg1;
        mode = (int)(uintptr_t)arg2;

        if (mode == IPC_M) {
                if (kauth_cred_geteuid(cred) == perm->uid ||
                    kauth_cred_geteuid(cred) == perm->cuid)
                        return (KAUTH_RESULT_ALLOW);
                return (KAUTH_RESULT_DEFER); /* EPERM */
        }

        mask = 0;

        if (kauth_cred_geteuid(cred) == perm->uid ||
            kauth_cred_geteuid(cred) == perm->cuid) {
                if (mode & IPC_R)
                        mask |= S_IRUSR;
                if (mode & IPC_W)
                        mask |= S_IWUSR;
                return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */);
        }

        if (kauth_cred_groupmember(cred, perm->gid) == 0 ||
            kauth_cred_groupmember(cred, perm->cgid) == 0) {
                if (mode & IPC_R)
                        mask |= S_IRGRP;
                if (mode & IPC_W)
                        mask |= S_IWGRP;
                return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */);
        }

        if (mode & IPC_R)
                mask |= S_IROTH;
        if (mode & IPC_W)
                mask |= S_IWOTH;
        return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */);
}

/*
 * Check for ipc permission
 */

int
ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode)
{
        int error;

        error = kauth_authorize_system(cred, KAUTH_SYSTEM_SYSVIPC,
            KAUTH_REQ_SYSTEM_SYSVIPC_BYPASS, perm, KAUTH_ARG(mode), NULL);
        if (error == 0)
                return (0);

        /* Adjust EPERM and EACCES errors until there's a better way to do this. */
        if (mode != IPC_M)
                error = EACCES;

        return error;
}

void
sysvipcfini(void)
{

        KASSERT(sysvipc_listener != NULL);
        kauth_unlisten_scope(sysvipc_listener);
        sysvipc_listener = NULL;
}

void
sysvipcinit(void)
{

        KASSERT(sysvipc_listener == NULL);

        sysvipc_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
            sysvipc_listener_cb, NULL);
}

static int
stub_sysvipc50_sysctl(SYSCTLFN_ARGS)
{
        return EPASSTHROUGH;
}

static int
sysctl_kern_sysvipc(SYSCTLFN_ARGS)
{
        void *where = oldp;
        size_t sz, *sizep = oldlenp;
#ifdef SYSVMSG
        struct msg_sysctl_info *msgsi = NULL;
#endif
#ifdef SYSVSEM
        struct sem_sysctl_info *semsi = NULL;
#endif
#ifdef SYSVSHM
        struct shm_sysctl_info *shmsi = NULL;
#endif
        size_t infosize, dssize, tsize, buflen;
        void *bf = NULL;
        char *start;
        int32_t nds;
        int i, error, ret;

/*
 * If present, call the compat sysctl() code.  If it handles the request
 * completely (either success or error), return.  Otherwise fallthrough
 * to the non-compat sysctl code.
 */

        MODULE_HOOK_CALL(sysvipc_sysctl_50_hook, (SYSCTLFN_CALL(rnode)),
            stub_sysvipc50_sysctl(SYSCTLFN_CALL(rnode)), error);
        if (error != EPASSTHROUGH)
                return error;

        if (namelen != 1)
                return EINVAL;

        start = where;
        buflen = *sizep;

        switch (*name) {
        case KERN_SYSVIPC_MSG_INFO:
#ifdef SYSVMSG
                infosize = sizeof(msgsi->msginfo);
                nds = msginfo.msgmni;
                dssize = sizeof(msgsi->msgids[0]);
                break;
#else
                return EINVAL;
#endif
        case KERN_SYSVIPC_SEM_INFO:
#ifdef SYSVSEM
                infosize = sizeof(semsi->seminfo);
                nds = seminfo.semmni;
                dssize = sizeof(semsi->semids[0]);
                break;
#else
                return EINVAL;
#endif
        case KERN_SYSVIPC_SHM_INFO:
#ifdef SYSVSHM
                infosize = sizeof(shmsi->shminfo);
                nds = shminfo.shmmni;
                dssize = sizeof(shmsi->shmids[0]);
                break;
#else
                return EINVAL;
#endif
        default:
                return EINVAL;
        }
        /*
         * Round infosize to 64 bit boundary if requesting more than just
         * the info structure or getting the total data size.
         */
        if (where == NULL || *sizep > infosize)
                infosize = roundup(infosize, sizeof(quad_t));
        tsize = infosize + nds * dssize;

        /* Return just the total size required. */
        if (where == NULL) {
                *sizep = tsize;
                return 0;
        }

        /* Not enough room for even the info struct. */
        if (buflen < infosize) {
                *sizep = 0;
                return ENOMEM;
        }
        sz = uimin(tsize, buflen);
        bf = kmem_zalloc(sz, KM_SLEEP);

        switch (*name) {
#ifdef SYSVMSG
        case KERN_SYSVIPC_MSG_INFO:
                msgsi = (struct msg_sysctl_info *)bf;
                msgsi->msginfo = msginfo;
                break;
#endif
#ifdef SYSVSEM
        case KERN_SYSVIPC_SEM_INFO:
                semsi = (struct sem_sysctl_info *)bf;
                semsi->seminfo = seminfo;
                break;
#endif
#ifdef SYSVSHM
        case KERN_SYSVIPC_SHM_INFO:
                shmsi = (struct shm_sysctl_info *)bf;
                shmsi->shminfo = shminfo;
                break;
#endif
        }
        buflen -= infosize;

        ret = 0;
        if (buflen > 0) {
                /* Fill in the IPC data structures.  */
                for (i = 0; i < nds; i++) {
                        if (buflen < dssize) {
                                ret = ENOMEM;
                                break;
                        }
                        switch (*name) {
#ifdef SYSVMSG
                        case KERN_SYSVIPC_MSG_INFO:
                                mutex_enter(&msgmutex);
                                SYSCTL_FILL_MSG(msqs[i].msq_u, msgsi->msgids[i]);
                                mutex_exit(&msgmutex);
                                break;
#endif
#ifdef SYSVSEM
                        case KERN_SYSVIPC_SEM_INFO:
                                SYSCTL_FILL_SEM(sema[i], semsi->semids[i]);
                                break;
#endif
#ifdef SYSVSHM
                        case KERN_SYSVIPC_SHM_INFO:
                                SYSCTL_FILL_SHM(shmsegs[i], shmsi->shmids[i]);
                                break;
#endif
                        }
                        buflen -= dssize;
                }
        }
        *sizep -= buflen;
        error = copyout(bf, start, *sizep);
        /* If copyout succeeded, use return code set earlier. */
        if (error == 0)
                error = ret;
        if (bf)
                kmem_free(bf, sz);
        return error;
}

SYSCTL_SETUP(sysctl_ipc_setup, "sysctl kern.ipc subtree setup")
{

        sysctl_createv(clog, 0, NULL, NULL,
                CTLFLAG_PERMANENT,
                CTLTYPE_NODE, "ipc",
                SYSCTL_DESCR("SysV IPC options"),
                NULL, 0, NULL, 0,
                CTL_KERN, KERN_SYSVIPC, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                CTLFLAG_PERMANENT,
                CTLTYPE_STRUCT, "sysvipc_info",
                SYSCTL_DESCR("System V style IPC information"),
                sysctl_kern_sysvipc, 0, NULL, 0,
                CTL_KERN, KERN_SYSVIPC, KERN_SYSVIPC_INFO, CTL_EOL);
}