uipc_syscalls.c

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/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1989, 1990, 1993
 *      The Regents of the University of California.  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.
 * 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.
 *
 *      @(#)uipc_syscalls.c     8.4 (Berkeley) 2/21/94
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_capsicum.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ktrace.h"
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/capsicum.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/malloc.h>
#include <sys/filedesc.h>
#include <sys/proc.h>
#include <sys/filio.h>
#include <sys/jail.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/rwlock.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/unpcb.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#ifdef COMPAT_FREEBSD32
#include <compat/freebsd32/freebsd32_util.h>
#endif
 
#include <net/vnet.h>
 
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
 
static int sendit(struct thread *td, int s, struct msghdr *mp, int flags);
static int recvit(struct thread *td, int s, struct msghdr *mp, void *namelenp);
 
static int accept1(struct thread *td, int s, struct sockaddr *uname,
                   socklen_t *anamelen, int flags);
static int sockargs(struct mbuf **, char *, socklen_t, int);
 
/*
 * Convert a user file descriptor to a kernel file entry and check if required
 * capability rights are present.
 * If required copy of current set of capability rights is returned.
 * A reference on the file entry is held upon returning.
 */
int
getsock_cap(struct thread *td, int fd, cap_rights_t *rightsp,
    struct file **fpp, u_int *fflagp, struct filecaps *havecapsp)
{
        struct file *fp;
        int error;
 
        error = fget_cap(td, fd, rightsp, &fp, havecapsp);
        if (error != 0)
                return (error);
        if (fp->f_type != DTYPE_SOCKET) {
                fdrop(fp, td);
                if (havecapsp != NULL)
                        filecaps_free(havecapsp);
                return (ENOTSOCK);
        }
        if (fflagp != NULL)
                *fflagp = fp->f_flag;
        *fpp = fp;
        return (0);
}
 
/*
 * System call interface to the socket abstraction.
 */
#if defined(COMPAT_43)
#define COMPAT_OLDSOCK
#endif
 
int
sys_socket(struct thread *td, struct socket_args *uap)
{
 
        return (kern_socket(td, uap->domain, uap->type, uap->protocol));
}
 
int
kern_socket(struct thread *td, int domain, int type, int protocol)
{
        struct socket *so;
        struct file *fp;
        int fd, error, oflag, fflag;
 
        AUDIT_ARG_SOCKET(domain, type, protocol);
 
        oflag = 0;
        fflag = 0;
        if ((type & SOCK_CLOEXEC) != 0) {
                type &= ~SOCK_CLOEXEC;
                oflag |= O_CLOEXEC;
        }
        if ((type & SOCK_NONBLOCK) != 0) {
                type &= ~SOCK_NONBLOCK;
                fflag |= FNONBLOCK;
        }
 
#ifdef MAC
        error = mac_socket_check_create(td->td_ucred, domain, type, protocol);
        if (error != 0)
                return (error);
#endif
        error = falloc(td, &fp, &fd, oflag);
        if (error != 0)
                return (error);
        /* An extra reference on `fp' has been held for us by falloc(). */
        error = socreate(domain, &so, type, protocol, td->td_ucred, td);
        if (error != 0) {
                fdclose(td, fp, fd);
        } else {
                finit(fp, FREAD | FWRITE | fflag, DTYPE_SOCKET, so, &socketops);
                if ((fflag & FNONBLOCK) != 0)
                        (void) fo_ioctl(fp, FIONBIO, &fflag, td->td_ucred, td);
                td->td_retval[0] = fd;
        }
        fdrop(fp, td);
        return (error);
}
 
int
sys_bind(struct thread *td, struct bind_args *uap)
{
        struct sockaddr *sa;
        int error;
 
        error = getsockaddr(&sa, uap->name, uap->namelen);
        if (error == 0) {
                error = kern_bindat(td, AT_FDCWD, uap->s, sa);
                free(sa, M_SONAME);
        }
        return (error);
}
 
int
kern_bindat(struct thread *td, int dirfd, int fd, struct sockaddr *sa)
{
        struct socket *so;
        struct file *fp;
        int error;
 
#ifdef CAPABILITY_MODE
        if (IN_CAPABILITY_MODE(td) && (dirfd == AT_FDCWD))
                return (ECAPMODE);
#endif
 
        AUDIT_ARG_FD(fd);
        AUDIT_ARG_SOCKADDR(td, dirfd, sa);
        error = getsock_cap(td, fd, &cap_bind_rights,
            &fp, NULL, NULL);
        if (error != 0)
                return (error);
        so = fp->f_data;
#ifdef KTRACE
        if (KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(sa);
#endif
#ifdef MAC
        error = mac_socket_check_bind(td->td_ucred, so, sa);
        if (error == 0) {
#endif
                if (dirfd == AT_FDCWD)
                        error = sobind(so, sa, td);
                else
                        error = sobindat(dirfd, so, sa, td);
#ifdef MAC
        }
#endif
        fdrop(fp, td);
        return (error);
}
 
int
sys_bindat(struct thread *td, struct bindat_args *uap)
{
        struct sockaddr *sa;
        int error;
 
        error = getsockaddr(&sa, uap->name, uap->namelen);
        if (error == 0) {
                error = kern_bindat(td, uap->fd, uap->s, sa);
                free(sa, M_SONAME);
        }
        return (error);
}
 
int
sys_listen(struct thread *td, struct listen_args *uap)
{
 
        return (kern_listen(td, uap->s, uap->backlog));
}
 
int
kern_listen(struct thread *td, int s, int backlog)
{
        struct socket *so;
        struct file *fp;
        int error;
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_listen_rights,
            &fp, NULL, NULL);
        if (error == 0) {
                so = fp->f_data;
#ifdef MAC
                error = mac_socket_check_listen(td->td_ucred, so);
                if (error == 0)
#endif
                        error = solisten(so, backlog, td);
                fdrop(fp, td);
        }
        return (error);
}
 
/*
 * accept1()
 */
static int
accept1(td, s, uname, anamelen, flags)
        struct thread *td;
        int s;
        struct sockaddr *uname;
        socklen_t *anamelen;
        int flags;
{
        struct sockaddr *name;
        socklen_t namelen;
        struct file *fp;
        int error;
 
        if (uname == NULL)
                return (kern_accept4(td, s, NULL, NULL, flags, NULL));
 
        error = copyin(anamelen, &namelen, sizeof (namelen));
        if (error != 0)
                return (error);
 
        error = kern_accept4(td, s, &name, &namelen, flags, &fp);
 
        if (error != 0)
                return (error);
 
        if (error == 0 && uname != NULL) {
#ifdef COMPAT_OLDSOCK
                if (SV_PROC_FLAG(td->td_proc, SV_AOUT) &&
                    (flags & ACCEPT4_COMPAT) != 0)
                        ((struct osockaddr *)name)->sa_family =
                            name->sa_family;
#endif
                error = copyout(name, uname, namelen);
        }
        if (error == 0)
                error = copyout(&namelen, anamelen,
                    sizeof(namelen));
        if (error != 0)
                fdclose(td, fp, td->td_retval[0]);
        fdrop(fp, td);
        free(name, M_SONAME);
        return (error);
}
 
int
kern_accept(struct thread *td, int s, struct sockaddr **name,
    socklen_t *namelen, struct file **fp)
{
        return (kern_accept4(td, s, name, namelen, ACCEPT4_INHERIT, fp));
}
 
int
kern_accept4(struct thread *td, int s, struct sockaddr **name,
    socklen_t *namelen, int flags, struct file **fp)
{
        struct file *headfp, *nfp = NULL;
        struct sockaddr *sa = NULL;
        struct socket *head, *so;
        struct filecaps fcaps;
        u_int fflag;
        pid_t pgid;
        int error, fd, tmp;
 
        if (name != NULL)
                *name = NULL;
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_accept_rights,
            &headfp, &fflag, &fcaps);
        if (error != 0)
                return (error);
        head = headfp->f_data;
        if (!SOLISTENING(head)) {
                error = EINVAL;
                goto done;
        }
#ifdef MAC
        error = mac_socket_check_accept(td->td_ucred, head);
        if (error != 0)
                goto done;
#endif
        error = falloc_caps(td, &nfp, &fd,
            (flags & SOCK_CLOEXEC) ? O_CLOEXEC : 0, &fcaps);
        if (error != 0)
                goto done;
        SOCK_LOCK(head);
        if (!SOLISTENING(head)) {
                SOCK_UNLOCK(head);
                error = EINVAL;
                goto noconnection;
        }
 
        error = solisten_dequeue(head, &so, flags);
        if (error != 0)
                goto noconnection;
 
        /* An extra reference on `nfp' has been held for us by falloc(). */
        td->td_retval[0] = fd;
 
        /* Connection has been removed from the listen queue. */
        KNOTE_UNLOCKED(&head->so_rdsel.si_note, 0);
 
        if (flags & ACCEPT4_INHERIT) {
                pgid = fgetown(&head->so_sigio);
                if (pgid != 0)
                        fsetown(pgid, &so->so_sigio);
        } else {
                fflag &= ~(FNONBLOCK | FASYNC);
                if (flags & SOCK_NONBLOCK)
                        fflag |= FNONBLOCK;
        }
 
        finit(nfp, fflag, DTYPE_SOCKET, so, &socketops);
        /* Sync socket nonblocking/async state with file flags */
        tmp = fflag & FNONBLOCK;
        (void) fo_ioctl(nfp, FIONBIO, &tmp, td->td_ucred, td);
        tmp = fflag & FASYNC;
        (void) fo_ioctl(nfp, FIOASYNC, &tmp, td->td_ucred, td);
        error = soaccept(so, &sa);
        if (error != 0)
                goto noconnection;
        if (sa == NULL) {
                if (name)
                        *namelen = 0;
                goto done;
        }
        AUDIT_ARG_SOCKADDR(td, AT_FDCWD, sa);
        if (name) {
                /* check sa_len before it is destroyed */
                if (*namelen > sa->sa_len)
                        *namelen = sa->sa_len;
#ifdef KTRACE
                if (KTRPOINT(td, KTR_STRUCT))
                        ktrsockaddr(sa);
#endif
                *name = sa;
                sa = NULL;
        }
noconnection:
        free(sa, M_SONAME);
 
        /*
         * close the new descriptor, assuming someone hasn't ripped it
         * out from under us.
         */
        if (error != 0)
                fdclose(td, nfp, fd);
 
        /*
         * Release explicitly held references before returning.  We return
         * a reference on nfp to the caller on success if they request it.
         */
done:
        if (nfp == NULL)
                filecaps_free(&fcaps);
        if (fp != NULL) {
                if (error == 0) {
                        *fp = nfp;
                        nfp = NULL;
                } else
                        *fp = NULL;
        }
        if (nfp != NULL)
                fdrop(nfp, td);
        fdrop(headfp, td);
        return (error);
}
 
int
sys_accept(td, uap)
        struct thread *td;
        struct accept_args *uap;
{
 
        return (accept1(td, uap->s, uap->name, uap->anamelen, ACCEPT4_INHERIT));
}
 
int
sys_accept4(td, uap)
        struct thread *td;
        struct accept4_args *uap;
{
 
        if (uap->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
                return (EINVAL);
 
        return (accept1(td, uap->s, uap->name, uap->anamelen, uap->flags));
}
 
#ifdef COMPAT_OLDSOCK
int
oaccept(struct thread *td, struct oaccept_args *uap)
{
 
        return (accept1(td, uap->s, uap->name, uap->anamelen,
            ACCEPT4_INHERIT | ACCEPT4_COMPAT));
}
#endif /* COMPAT_OLDSOCK */
 
int
sys_connect(struct thread *td, struct connect_args *uap)
{
        struct sockaddr *sa;
        int error;
 
        error = getsockaddr(&sa, uap->name, uap->namelen);
        if (error == 0) {
                error = kern_connectat(td, AT_FDCWD, uap->s, sa);
                free(sa, M_SONAME);
        }
        return (error);
}
 
int
kern_connectat(struct thread *td, int dirfd, int fd, struct sockaddr *sa)
{
        struct socket *so;
        struct file *fp;
        int error;
 
#ifdef CAPABILITY_MODE
        if (IN_CAPABILITY_MODE(td) && (dirfd == AT_FDCWD))
                return (ECAPMODE);
#endif
 
        AUDIT_ARG_FD(fd);
        AUDIT_ARG_SOCKADDR(td, dirfd, sa);
        error = getsock_cap(td, fd, &cap_connect_rights,
            &fp, NULL, NULL);
        if (error != 0)
                return (error);
        so = fp->f_data;
        if (so->so_state & SS_ISCONNECTING) {
                error = EALREADY;
                goto done1;
        }
#ifdef KTRACE
        if (KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(sa);
#endif
#ifdef MAC
        error = mac_socket_check_connect(td->td_ucred, so, sa);
        if (error != 0)
                goto bad;
#endif
        error = soconnectat(dirfd, so, sa, td);
        if (error != 0)
                goto bad;
        if ((so->so_state & SS_NBIO) && (so->so_state & SS_ISCONNECTING)) {
                error = EINPROGRESS;
                goto done1;
        }
        SOCK_LOCK(so);
        while ((so->so_state & SS_ISCONNECTING) && so->so_error == 0) {
                error = msleep(&so->so_timeo, &so->so_lock, PSOCK | PCATCH,
                    "connec", 0);
                if (error != 0)
                        break;
        }
        if (error == 0) {
                error = so->so_error;
                so->so_error = 0;
        }
        SOCK_UNLOCK(so);
bad:
        if (error == ERESTART)
                error = EINTR;
done1:
        fdrop(fp, td);
        return (error);
}
 
int
sys_connectat(struct thread *td, struct connectat_args *uap)
{
        struct sockaddr *sa;
        int error;
 
        error = getsockaddr(&sa, uap->name, uap->namelen);
        if (error == 0) {
                error = kern_connectat(td, uap->fd, uap->s, sa);
                free(sa, M_SONAME);
        }
        return (error);
}
 
int
kern_socketpair(struct thread *td, int domain, int type, int protocol,
    int *rsv)
{
        struct file *fp1, *fp2;
        struct socket *so1, *so2;
        int fd, error, oflag, fflag;
 
        AUDIT_ARG_SOCKET(domain, type, protocol);
 
        oflag = 0;
        fflag = 0;
        if ((type & SOCK_CLOEXEC) != 0) {
                type &= ~SOCK_CLOEXEC;
                oflag |= O_CLOEXEC;
        }
        if ((type & SOCK_NONBLOCK) != 0) {
                type &= ~SOCK_NONBLOCK;
                fflag |= FNONBLOCK;
        }
#ifdef MAC
        /* We might want to have a separate check for socket pairs. */
        error = mac_socket_check_create(td->td_ucred, domain, type,
            protocol);
        if (error != 0)
                return (error);
#endif
        error = socreate(domain, &so1, type, protocol, td->td_ucred, td);
        if (error != 0)
                return (error);
        error = socreate(domain, &so2, type, protocol, td->td_ucred, td);
        if (error != 0)
                goto free1;
        /* On success extra reference to `fp1' and 'fp2' is set by falloc. */
        error = falloc(td, &fp1, &fd, oflag);
        if (error != 0)
                goto free2;
        rsv[0] = fd;
        fp1->f_data = so1;      /* so1 already has ref count */
        error = falloc(td, &fp2, &fd, oflag);
        if (error != 0)
                goto free3;
        fp2->f_data = so2;      /* so2 already has ref count */
        rsv[1] = fd;
        error = soconnect2(so1, so2);
        if (error != 0)
                goto free4;
        if (type == SOCK_DGRAM) {
                /*
                 * Datagram socket connection is asymmetric.
                 */
                 error = soconnect2(so2, so1);
                 if (error != 0)
                        goto free4;
        } else if (so1->so_proto->pr_flags & PR_CONNREQUIRED) {
                struct unpcb *unp, *unp2;
                unp = sotounpcb(so1);
                unp2 = sotounpcb(so2);
                /* 
                 * No need to lock the unps, because the sockets are brand-new.
                 * No other threads can be using them yet
                 */
                unp_copy_peercred(td, unp, unp2, unp);
        }
        finit(fp1, FREAD | FWRITE | fflag, DTYPE_SOCKET, fp1->f_data,
            &socketops);
        finit(fp2, FREAD | FWRITE | fflag, DTYPE_SOCKET, fp2->f_data,
            &socketops);
        if ((fflag & FNONBLOCK) != 0) {
                (void) fo_ioctl(fp1, FIONBIO, &fflag, td->td_ucred, td);
                (void) fo_ioctl(fp2, FIONBIO, &fflag, td->td_ucred, td);
        }
        fdrop(fp1, td);
        fdrop(fp2, td);
        return (0);
free4:
        fdclose(td, fp2, rsv[1]);
        fdrop(fp2, td);
free3:
        fdclose(td, fp1, rsv[0]);
        fdrop(fp1, td);
free2:
        if (so2 != NULL)
                (void)soclose(so2);
free1:
        if (so1 != NULL)
                (void)soclose(so1);
        return (error);
}
 
int
sys_socketpair(struct thread *td, struct socketpair_args *uap)
{
        int error, sv[2];
 
        error = kern_socketpair(td, uap->domain, uap->type,
            uap->protocol, sv);
        if (error != 0)
                return (error);
        error = copyout(sv, uap->rsv, 2 * sizeof(int));
        if (error != 0) {
                (void)kern_close(td, sv[0]);
                (void)kern_close(td, sv[1]);
        }
        return (error);
}
 
static int
sendit(struct thread *td, int s, struct msghdr *mp, int flags)
{
        struct mbuf *control;
        struct sockaddr *to;
        int error;
 
#ifdef CAPABILITY_MODE
        if (IN_CAPABILITY_MODE(td) && (mp->msg_name != NULL))
                return (ECAPMODE);
#endif
 
        if (mp->msg_name != NULL) {
                error = getsockaddr(&to, mp->msg_name, mp->msg_namelen);
                if (error != 0) {
                        to = NULL;
                        goto bad;
                }
                mp->msg_name = to;
        } else {
                to = NULL;
        }
 
        if (mp->msg_control) {
                if (mp->msg_controllen < sizeof(struct cmsghdr)
#ifdef COMPAT_OLDSOCK
                    && (mp->msg_flags != MSG_COMPAT ||
                    !SV_PROC_FLAG(td->td_proc, SV_AOUT))
#endif
                ) {
                        error = EINVAL;
                        goto bad;
                }
                error = sockargs(&control, mp->msg_control,
                    mp->msg_controllen, MT_CONTROL);
                if (error != 0)
                        goto bad;
#ifdef COMPAT_OLDSOCK
                if (mp->msg_flags == MSG_COMPAT &&
                    SV_PROC_FLAG(td->td_proc, SV_AOUT)) {
                        struct cmsghdr *cm;
 
                        M_PREPEND(control, sizeof(*cm), M_WAITOK);
                        cm = mtod(control, struct cmsghdr *);
                        cm->cmsg_len = control->m_len;
                        cm->cmsg_level = SOL_SOCKET;
                        cm->cmsg_type = SCM_RIGHTS;
                }
#endif
        } else {
                control = NULL;
        }
 
        error = kern_sendit(td, s, mp, flags, control, UIO_USERSPACE);
 
bad:
        free(to, M_SONAME);
        return (error);
}
 
int
kern_sendit(struct thread *td, int s, struct msghdr *mp, int flags,
    struct mbuf *control, enum uio_seg segflg)
{
        struct file *fp;
        struct uio auio;
        struct iovec *iov;
        struct socket *so;
        cap_rights_t *rights;
#ifdef KTRACE
        struct uio *ktruio = NULL;
#endif
        ssize_t len;
        int i, error;
 
        AUDIT_ARG_FD(s);
        rights = &cap_send_rights;
        if (mp->msg_name != NULL) {
                AUDIT_ARG_SOCKADDR(td, AT_FDCWD, mp->msg_name);
                rights = &cap_send_connect_rights;
        }
        error = getsock_cap(td, s, rights, &fp, NULL, NULL);
        if (error != 0) {
                m_freem(control);
                return (error);
        }
        so = (struct socket *)fp->f_data;
 
#ifdef KTRACE
        if (mp->msg_name != NULL && KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(mp->msg_name);
#endif
#ifdef MAC
        if (mp->msg_name != NULL) {
                error = mac_socket_check_connect(td->td_ucred, so,
                    mp->msg_name);
                if (error != 0) {
                        m_freem(control);
                        goto bad;
                }
        }
        error = mac_socket_check_send(td->td_ucred, so);
        if (error != 0) {
                m_freem(control);
                goto bad;
        }
#endif
 
        auio.uio_iov = mp->msg_iov;
        auio.uio_iovcnt = mp->msg_iovlen;
        auio.uio_segflg = segflg;
        auio.uio_rw = UIO_WRITE;
        auio.uio_td = td;
        auio.uio_offset = 0;                    /* XXX */
        auio.uio_resid = 0;
        iov = mp->msg_iov;
        for (i = 0; i < mp->msg_iovlen; i++, iov++) {
                if ((auio.uio_resid += iov->iov_len) < 0) {
                        error = EINVAL;
                        m_freem(control);
                        goto bad;
                }
        }
#ifdef KTRACE
        if (KTRPOINT(td, KTR_GENIO))
                ktruio = cloneuio(&auio);
#endif
        len = auio.uio_resid;
        error = sosend(so, mp->msg_name, &auio, 0, control, flags, td);
        if (error != 0) {
                if (auio.uio_resid != len &&
                    (so->so_proto->pr_flags & PR_ATOMIC) == 0 &&
                    (error == ERESTART || error == EINTR ||
                    error == EWOULDBLOCK))
                        error = 0;
                /* Generation of SIGPIPE can be controlled per socket */
                if (error == EPIPE && !(so->so_options & SO_NOSIGPIPE) &&
                    !(flags & MSG_NOSIGNAL)) {
                        PROC_LOCK(td->td_proc);
                        tdsignal(td, SIGPIPE);
                        PROC_UNLOCK(td->td_proc);
                }
        }
        if (error == 0)
                td->td_retval[0] = len - auio.uio_resid;
#ifdef KTRACE
        if (ktruio != NULL) {
                ktruio->uio_resid = td->td_retval[0];
                ktrgenio(s, UIO_WRITE, ktruio, error);
        }
#endif
bad:
        fdrop(fp, td);
        return (error);
}
 
int
sys_sendto(struct thread *td, struct sendto_args *uap)
{
        struct msghdr msg;
        struct iovec aiov;
 
        msg.msg_name = __DECONST(void *, uap->to);
        msg.msg_namelen = uap->tolen;
        msg.msg_iov = &aiov;
        msg.msg_iovlen = 1;
        msg.msg_control = 0;
#ifdef COMPAT_OLDSOCK
        if (SV_PROC_FLAG(td->td_proc, SV_AOUT))
                msg.msg_flags = 0;
#endif
        aiov.iov_base = __DECONST(void *, uap->buf);
        aiov.iov_len = uap->len;
        return (sendit(td, uap->s, &msg, uap->flags));
}
 
#ifdef COMPAT_OLDSOCK
int
osend(struct thread *td, struct osend_args *uap)
{
        struct msghdr msg;
        struct iovec aiov;
 
        msg.msg_name = 0;
        msg.msg_namelen = 0;
        msg.msg_iov = &aiov;
        msg.msg_iovlen = 1;
        aiov.iov_base = __DECONST(void *, uap->buf);
        aiov.iov_len = uap->len;
        msg.msg_control = 0;
        msg.msg_flags = 0;
        return (sendit(td, uap->s, &msg, uap->flags));
}
 
int
osendmsg(struct thread *td, struct osendmsg_args *uap)
{
        struct msghdr msg;
        struct iovec *iov;
        int error;
 
        error = copyin(uap->msg, &msg, sizeof (struct omsghdr));
        if (error != 0)
                return (error);
        error = copyiniov(msg.msg_iov, msg.msg_iovlen, &iov, EMSGSIZE);
        if (error != 0)
                return (error);
        msg.msg_iov = iov;
        msg.msg_flags = MSG_COMPAT;
        error = sendit(td, uap->s, &msg, uap->flags);
        free(iov, M_IOV);
        return (error);
}
#endif
 
int
sys_sendmsg(struct thread *td, struct sendmsg_args *uap)
{
        struct msghdr msg;
        struct iovec *iov;
        int error;
 
        error = copyin(uap->msg, &msg, sizeof (msg));
        if (error != 0)
                return (error);
        error = copyiniov(msg.msg_iov, msg.msg_iovlen, &iov, EMSGSIZE);
        if (error != 0)
                return (error);
        msg.msg_iov = iov;
#ifdef COMPAT_OLDSOCK
        if (SV_PROC_FLAG(td->td_proc, SV_AOUT))
                msg.msg_flags = 0;
#endif
        error = sendit(td, uap->s, &msg, uap->flags);
        free(iov, M_IOV);
        return (error);
}
 
int
kern_recvit(struct thread *td, int s, struct msghdr *mp, enum uio_seg fromseg,
    struct mbuf **controlp)
{
        struct uio auio;
        struct iovec *iov;
        struct mbuf *control, *m;
        caddr_t ctlbuf;
        struct file *fp;
        struct socket *so;
        struct sockaddr *fromsa = NULL;
#ifdef KTRACE
        struct uio *ktruio = NULL;
#endif
        ssize_t len;
        int error, i;
 
        if (controlp != NULL)
                *controlp = NULL;
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_recv_rights,
            &fp, NULL, NULL);
        if (error != 0)
                return (error);
        so = fp->f_data;
 
#ifdef MAC
        error = mac_socket_check_receive(td->td_ucred, so);
        if (error != 0) {
                fdrop(fp, td);
                return (error);
        }
#endif
 
        auio.uio_iov = mp->msg_iov;
        auio.uio_iovcnt = mp->msg_iovlen;
        auio.uio_segflg = UIO_USERSPACE;
        auio.uio_rw = UIO_READ;
        auio.uio_td = td;
        auio.uio_offset = 0;                    /* XXX */
        auio.uio_resid = 0;
        iov = mp->msg_iov;
        for (i = 0; i < mp->msg_iovlen; i++, iov++) {
                if ((auio.uio_resid += iov->iov_len) < 0) {
                        fdrop(fp, td);
                        return (EINVAL);
                }
        }
#ifdef KTRACE
        if (KTRPOINT(td, KTR_GENIO))
                ktruio = cloneuio(&auio);
#endif
        control = NULL;
        len = auio.uio_resid;
        error = soreceive(so, &fromsa, &auio, NULL,
            (mp->msg_control || controlp) ? &control : NULL,
            &mp->msg_flags);
        if (error != 0) {
                if (auio.uio_resid != len && (error == ERESTART ||
                    error == EINTR || error == EWOULDBLOCK))
                        error = 0;
        }
        if (fromsa != NULL)
                AUDIT_ARG_SOCKADDR(td, AT_FDCWD, fromsa);
#ifdef KTRACE
        if (ktruio != NULL) {
                ktruio->uio_resid = len - auio.uio_resid;
                ktrgenio(s, UIO_READ, ktruio, error);
        }
#endif
        if (error != 0)
                goto out;
        td->td_retval[0] = len - auio.uio_resid;
        if (mp->msg_name) {
                len = mp->msg_namelen;
                if (len <= 0 || fromsa == NULL)
                        len = 0;
                else {
                        /* save sa_len before it is destroyed by MSG_COMPAT */
                        len = MIN(len, fromsa->sa_len);
#ifdef COMPAT_OLDSOCK
                        if ((mp->msg_flags & MSG_COMPAT) != 0 &&
                            SV_PROC_FLAG(td->td_proc, SV_AOUT))
                                ((struct osockaddr *)fromsa)->sa_family =
                                    fromsa->sa_family;
#endif
                        if (fromseg == UIO_USERSPACE) {
                                error = copyout(fromsa, mp->msg_name,
                                    (unsigned)len);
                                if (error != 0)
                                        goto out;
                        } else
                                bcopy(fromsa, mp->msg_name, len);
                }
                mp->msg_namelen = len;
        }
        if (mp->msg_control && controlp == NULL) {
#ifdef COMPAT_OLDSOCK
                /*
                 * We assume that old recvmsg calls won't receive access
                 * rights and other control info, esp. as control info
                 * is always optional and those options didn't exist in 4.3.
                 * If we receive rights, trim the cmsghdr; anything else
                 * is tossed.
                 */
                if (control && (mp->msg_flags & MSG_COMPAT) != 0 &&
                    SV_PROC_FLAG(td->td_proc, SV_AOUT)) {
                        if (mtod(control, struct cmsghdr *)->cmsg_level !=
                            SOL_SOCKET ||
                            mtod(control, struct cmsghdr *)->cmsg_type !=
                            SCM_RIGHTS) {
                                mp->msg_controllen = 0;
                                goto out;
                        }
                        control->m_len -= sizeof (struct cmsghdr);
                        control->m_data += sizeof (struct cmsghdr);
                }
#endif
                ctlbuf = mp->msg_control;
                len = mp->msg_controllen;
                mp->msg_controllen = 0;
                for (m = control; m != NULL && len >= m->m_len; m = m->m_next) {
                        if ((error = copyout(mtod(m, caddr_t), ctlbuf,
                            m->m_len)) != 0)
                                goto out;
 
                        ctlbuf += m->m_len;
                        len -= m->m_len;
                        mp->msg_controllen += m->m_len;
                }
                if (m != NULL) {
                        mp->msg_flags |= MSG_CTRUNC;
                        m_dispose_extcontrolm(m);
                }
        }
out:
        fdrop(fp, td);
#ifdef KTRACE
        if (fromsa && KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(fromsa);
#endif
        free(fromsa, M_SONAME);
 
        if (error == 0 && controlp != NULL)
                *controlp = control;
        else if (control != NULL) {
                if (error != 0)
                        m_dispose_extcontrolm(control);
                m_freem(control);
        }
 
        return (error);
}
 
static int
recvit(struct thread *td, int s, struct msghdr *mp, void *namelenp)
{
        int error;
 
        error = kern_recvit(td, s, mp, UIO_USERSPACE, NULL);
        if (error != 0)
                return (error);
        if (namelenp != NULL) {
                error = copyout(&mp->msg_namelen, namelenp, sizeof (socklen_t));
#ifdef COMPAT_OLDSOCK
                if ((mp->msg_flags & MSG_COMPAT) != 0 &&
                    SV_PROC_FLAG(td->td_proc, SV_AOUT))
                        error = 0;      /* old recvfrom didn't check */
#endif
        }
        return (error);
}
 
static int
kern_recvfrom(struct thread *td, int s, void *buf, size_t len, int flags,
    struct sockaddr *from, socklen_t *fromlenaddr)
{
        struct msghdr msg;
        struct iovec aiov;
        int error;
 
        if (fromlenaddr != NULL) {
                error = copyin(fromlenaddr, &msg.msg_namelen,
                    sizeof (msg.msg_namelen));
                if (error != 0)
                        goto done2;
        } else {
                msg.msg_namelen = 0;
        }
        msg.msg_name = from;
        msg.msg_iov = &aiov;
        msg.msg_iovlen = 1;
        aiov.iov_base = buf;
        aiov.iov_len = len;
        msg.msg_control = 0;
        msg.msg_flags = flags;
        error = recvit(td, s, &msg, fromlenaddr);
done2:
        return (error);
}
 
int
sys_recvfrom(struct thread *td, struct recvfrom_args *uap)
{
        return (kern_recvfrom(td, uap->s, uap->buf, uap->len,
            uap->flags, uap->from, uap->fromlenaddr));
}
 
 
#ifdef COMPAT_OLDSOCK
int
orecvfrom(struct thread *td, struct orecvfrom_args *uap)
{
        return (kern_recvfrom(td, uap->s, uap->buf, uap->len,
            uap->flags | MSG_COMPAT, uap->from, uap->fromlenaddr));
}
#endif
 
#ifdef COMPAT_OLDSOCK
int
orecv(struct thread *td, struct orecv_args *uap)
{
        struct msghdr msg;
        struct iovec aiov;
 
        msg.msg_name = 0;
        msg.msg_namelen = 0;
        msg.msg_iov = &aiov;
        msg.msg_iovlen = 1;
        aiov.iov_base = uap->buf;
        aiov.iov_len = uap->len;
        msg.msg_control = 0;
        msg.msg_flags = uap->flags;
        return (recvit(td, uap->s, &msg, NULL));
}
 
/*
 * Old recvmsg.  This code takes advantage of the fact that the old msghdr
 * overlays the new one, missing only the flags, and with the (old) access
 * rights where the control fields are now.
 */
int
orecvmsg(struct thread *td, struct orecvmsg_args *uap)
{
        struct msghdr msg;
        struct iovec *iov;
        int error;
 
        error = copyin(uap->msg, &msg, sizeof (struct omsghdr));
        if (error != 0)
                return (error);
        error = copyiniov(msg.msg_iov, msg.msg_iovlen, &iov, EMSGSIZE);
        if (error != 0)
                return (error);
        msg.msg_flags = uap->flags | MSG_COMPAT;
        msg.msg_iov = iov;
        error = recvit(td, uap->s, &msg, &uap->msg->msg_namelen);
        if (msg.msg_controllen && error == 0)
                error = copyout(&msg.msg_controllen,
                    &uap->msg->msg_accrightslen, sizeof (int));
        free(iov, M_IOV);
        return (error);
}
#endif
 
int
sys_recvmsg(struct thread *td, struct recvmsg_args *uap)
{
        struct msghdr msg;
        struct iovec *uiov, *iov;
        int error;
 
        error = copyin(uap->msg, &msg, sizeof (msg));
        if (error != 0)
                return (error);
        error = copyiniov(msg.msg_iov, msg.msg_iovlen, &iov, EMSGSIZE);
        if (error != 0)
                return (error);
        msg.msg_flags = uap->flags;
#ifdef COMPAT_OLDSOCK
        if (SV_PROC_FLAG(td->td_proc, SV_AOUT))
                msg.msg_flags &= ~MSG_COMPAT;
#endif
        uiov = msg.msg_iov;
        msg.msg_iov = iov;
        error = recvit(td, uap->s, &msg, NULL);
        if (error == 0) {
                msg.msg_iov = uiov;
                error = copyout(&msg, uap->msg, sizeof(msg));
        }
        free(iov, M_IOV);
        return (error);
}
 
int
sys_shutdown(struct thread *td, struct shutdown_args *uap)
{
 
        return (kern_shutdown(td, uap->s, uap->how));
}
 
int
kern_shutdown(struct thread *td, int s, int how)
{
        struct socket *so;
        struct file *fp;
        int error;
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_shutdown_rights,
            &fp, NULL, NULL);
        if (error == 0) {
                so = fp->f_data;
                error = soshutdown(so, how);
                /*
                 * Previous versions did not return ENOTCONN, but 0 in
                 * case the socket was not connected. Some important
                 * programs like syslogd up to r279016, 2015-02-19,
                 * still depend on this behavior.
                 */
                if (error == ENOTCONN &&
                    td->td_proc->p_osrel < P_OSREL_SHUTDOWN_ENOTCONN)
                        error = 0;
                fdrop(fp, td);
        }
        return (error);
}
 
int
sys_setsockopt(struct thread *td, struct setsockopt_args *uap)
{
 
        return (kern_setsockopt(td, uap->s, uap->level, uap->name,
            uap->val, UIO_USERSPACE, uap->valsize));
}
 
int
kern_setsockopt(struct thread *td, int s, int level, int name, const void *val,
    enum uio_seg valseg, socklen_t valsize)
{
        struct socket *so;
        struct file *fp;
        struct sockopt sopt;
        int error;
 
        if (val == NULL && valsize != 0)
                return (EFAULT);
        if ((int)valsize < 0)
                return (EINVAL);
 
        sopt.sopt_dir = SOPT_SET;
        sopt.sopt_level = level;
        sopt.sopt_name = name;
        sopt.sopt_val = __DECONST(void *, val);
        sopt.sopt_valsize = valsize;
        switch (valseg) {
        case UIO_USERSPACE:
                sopt.sopt_td = td;
                break;
        case UIO_SYSSPACE:
                sopt.sopt_td = NULL;
                break;
        default:
                panic("kern_setsockopt called with bad valseg");
        }
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_setsockopt_rights,
            &fp, NULL, NULL);
        if (error == 0) {
                so = fp->f_data;
                error = sosetopt(so, &sopt);
                fdrop(fp, td);
        }
        return(error);
}
 
int
sys_getsockopt(struct thread *td, struct getsockopt_args *uap)
{
        socklen_t valsize;
        int error;
 
        if (uap->val) {
                error = copyin(uap->avalsize, &valsize, sizeof (valsize));
                if (error != 0)
                        return (error);
        }
 
        error = kern_getsockopt(td, uap->s, uap->level, uap->name,
            uap->val, UIO_USERSPACE, &valsize);
 
        if (error == 0)
                error = copyout(&valsize, uap->avalsize, sizeof (valsize));
        return (error);
}
 
/*
 * Kernel version of getsockopt.
 * optval can be a userland or userspace. optlen is always a kernel pointer.
 */
int
kern_getsockopt(struct thread *td, int s, int level, int name, void *val,
    enum uio_seg valseg, socklen_t *valsize)
{
        struct socket *so;
        struct file *fp;
        struct sockopt sopt;
        int error;
 
        if (val == NULL)
                *valsize = 0;
        if ((int)*valsize < 0)
                return (EINVAL);
 
        sopt.sopt_dir = SOPT_GET;
        sopt.sopt_level = level;
        sopt.sopt_name = name;
        sopt.sopt_val = val;
        sopt.sopt_valsize = (size_t)*valsize; /* checked non-negative above */
        switch (valseg) {
        case UIO_USERSPACE:
                sopt.sopt_td = td;
                break;
        case UIO_SYSSPACE:
                sopt.sopt_td = NULL;
                break;
        default:
                panic("kern_getsockopt called with bad valseg");
        }
 
        AUDIT_ARG_FD(s);
        error = getsock_cap(td, s, &cap_getsockopt_rights,
            &fp, NULL, NULL);
        if (error == 0) {
                so = fp->f_data;
                error = sogetopt(so, &sopt);
                *valsize = sopt.sopt_valsize;
                fdrop(fp, td);
        }
        return (error);
}
 
static int
user_getsockname(struct thread *td, int fdes, struct sockaddr *asa,
    socklen_t *alen, bool compat)
{
        struct sockaddr *sa;
        socklen_t len;
        int error;
 
        error = copyin(alen, &len, sizeof(len));
        if (error != 0)
                return (error);
 
        error = kern_getsockname(td, fdes, &sa, &len);
        if (error != 0)
                return (error);
 
        if (len != 0) {
#ifdef COMPAT_OLDSOCK
                if (compat && SV_PROC_FLAG(td->td_proc, SV_AOUT))
                        ((struct osockaddr *)sa)->sa_family = sa->sa_family;
#endif
                error = copyout(sa, asa, len);
        }
        free(sa, M_SONAME);
        if (error == 0)
                error = copyout(&len, alen, sizeof(len));
        return (error);
}
 
int
kern_getsockname(struct thread *td, int fd, struct sockaddr **sa,
    socklen_t *alen)
{
        struct socket *so;
        struct file *fp;
        socklen_t len;
        int error;
 
        AUDIT_ARG_FD(fd);
        error = getsock_cap(td, fd, &cap_getsockname_rights,
            &fp, NULL, NULL);
        if (error != 0)
                return (error);
        so = fp->f_data;
        *sa = NULL;
        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_sockaddr)(so, sa);
        CURVNET_RESTORE();
        if (error != 0)
                goto bad;
        if (*sa == NULL)
                len = 0;
        else
                len = MIN(*alen, (*sa)->sa_len);
        *alen = len;
#ifdef KTRACE
        if (KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(*sa);
#endif
bad:
        fdrop(fp, td);
        if (error != 0 && *sa != NULL) {
                free(*sa, M_SONAME);
                *sa = NULL;
        }
        return (error);
}
 
int
sys_getsockname(struct thread *td, struct getsockname_args *uap)
{
        return (user_getsockname(td, uap->fdes, uap->asa, uap->alen, false));
}
 
#ifdef COMPAT_OLDSOCK
int
ogetsockname(struct thread *td, struct ogetsockname_args *uap)
{
        return (user_getsockname(td, uap->fdes, uap->asa, uap->alen, true));
}
#endif /* COMPAT_OLDSOCK */
 
static int
user_getpeername(struct thread *td, int fdes, struct sockaddr *asa,
    socklen_t *alen, bool compat)
{
        struct sockaddr *sa;
        socklen_t len;
        int error;
 
        error = copyin(alen, &len, sizeof (len));
        if (error != 0)
                return (error);
 
        error = kern_getpeername(td, fdes, &sa, &len);
        if (error != 0)
                return (error);
 
        if (len != 0) {
#ifdef COMPAT_OLDSOCK
                if (compat && SV_PROC_FLAG(td->td_proc, SV_AOUT))
                        ((struct osockaddr *)sa)->sa_family = sa->sa_family;
#endif
                error = copyout(sa, asa, len);
        }
        free(sa, M_SONAME);
        if (error == 0)
                error = copyout(&len, alen, sizeof(len));
        return (error);
}
 
int
kern_getpeername(struct thread *td, int fd, struct sockaddr **sa,
    socklen_t *alen)
{
        struct socket *so;
        struct file *fp;
        socklen_t len;
        int error;
 
        AUDIT_ARG_FD(fd);
        error = getsock_cap(td, fd, &cap_getpeername_rights,
            &fp, NULL, NULL);
        if (error != 0)
                return (error);
        so = fp->f_data;
        if ((so->so_state & (SS_ISCONNECTED|SS_ISCONFIRMING)) == 0) {
                error = ENOTCONN;
                goto done;
        }
        *sa = NULL;
        CURVNET_SET(so->so_vnet);
        error = (*so->so_proto->pr_usrreqs->pru_peeraddr)(so, sa);
        CURVNET_RESTORE();
        if (error != 0)
                goto bad;
        if (*sa == NULL)
                len = 0;
        else
                len = MIN(*alen, (*sa)->sa_len);
        *alen = len;
#ifdef KTRACE
        if (KTRPOINT(td, KTR_STRUCT))
                ktrsockaddr(*sa);
#endif
bad:
        if (error != 0 && *sa != NULL) {
                free(*sa, M_SONAME);
                *sa = NULL;
        }
done:
        fdrop(fp, td);
        return (error);
}
 
int
sys_getpeername(struct thread *td, struct getpeername_args *uap)
{
        return (user_getpeername(td, uap->fdes, uap->asa, uap->alen, false));
}
 
#ifdef COMPAT_OLDSOCK
int
ogetpeername(struct thread *td, struct ogetpeername_args *uap)
{
        return (user_getpeername(td, uap->fdes, uap->asa, uap->alen, true));
}
#endif /* COMPAT_OLDSOCK */
 
static int
sockargs(struct mbuf **mp, char *buf, socklen_t buflen, int type)
{
        struct sockaddr *sa;
        struct mbuf *m;
        int error;
 
        if (buflen > MLEN) {
#ifdef COMPAT_OLDSOCK
                if (type == MT_SONAME && buflen <= 112 &&
                    SV_CURPROC_FLAG(SV_AOUT))
                        buflen = MLEN;          /* unix domain compat. hack */
                else
#endif
                        if (buflen > MCLBYTES)
                                return (EINVAL);
        }
        m = m_get2(buflen, M_WAITOK, type, 0);
        m->m_len = buflen;
        error = copyin(buf, mtod(m, void *), buflen);
        if (error != 0)
                (void) m_free(m);
        else {
                *mp = m;
                if (type == MT_SONAME) {
                        sa = mtod(m, struct sockaddr *);
 
#if defined(COMPAT_OLDSOCK) && BYTE_ORDER != BIG_ENDIAN
                        if (sa->sa_family == 0 && sa->sa_len < AF_MAX &&
                            SV_CURPROC_FLAG(SV_AOUT))
                                sa->sa_family = sa->sa_len;
#endif
                        sa->sa_len = buflen;
                }
        }
        return (error);
}
 
int
getsockaddr(struct sockaddr **namp, const struct sockaddr *uaddr, size_t len)
{
        struct sockaddr *sa;
        int error;
 
        if (len > SOCK_MAXADDRLEN)
                return (ENAMETOOLONG);
        if (len < offsetof(struct sockaddr, sa_data[0]))
                return (EINVAL);
        sa = malloc(len, M_SONAME, M_WAITOK);
        error = copyin(uaddr, sa, len);
        if (error != 0) {
                free(sa, M_SONAME);
        } else {
#if defined(COMPAT_OLDSOCK) && BYTE_ORDER != BIG_ENDIAN
                if (sa->sa_family == 0 && sa->sa_len < AF_MAX &&
                    SV_CURPROC_FLAG(SV_AOUT))
                        sa->sa_family = sa->sa_len;
#endif
                sa->sa_len = len;
                *namp = sa;
        }
        return (error);
}
 
/*
 * Dispose of externalized rights from an SCM_RIGHTS message.  This function
 * should be used in error or truncation cases to avoid leaking file descriptors
 * into the recipient's (the current thread's) table.
 */
void
m_dispose_extcontrolm(struct mbuf *m)
{
        struct cmsghdr *cm;
        struct file *fp;
        struct thread *td;
        socklen_t clen, datalen;
        int error, fd, *fds, nfd;
 
        td = curthread;
        for (; m != NULL; m = m->m_next) {
                if (m->m_type != MT_EXTCONTROL)
                        continue;
                cm = mtod(m, struct cmsghdr *);
                clen = m->m_len;
                while (clen > 0) {
                        if (clen < sizeof(*cm))
                                panic("%s: truncated mbuf %p", __func__, m);
                        datalen = CMSG_SPACE(cm->cmsg_len - CMSG_SPACE(0));
                        if (clen < datalen)
                                panic("%s: truncated mbuf %p", __func__, m);
 
                        if (cm->cmsg_level == SOL_SOCKET &&
                            cm->cmsg_type == SCM_RIGHTS) {
                                fds = (int *)CMSG_DATA(cm);
                                nfd = (cm->cmsg_len - CMSG_SPACE(0)) /
                                    sizeof(int);
 
                                while (nfd-- > 0) {
                                        fd = *fds++;
                                        error = fget(td, fd, &cap_no_rights,
                                            &fp);
                                        if (error == 0) {
                                                fdclose(td, fp, fd);
                                                fdrop(fp, td);
                                        }
                                }
                        }
                        clen -= datalen;
                        cm = (struct cmsghdr *)((uint8_t *)cm + datalen);
                }
                m_chtype(m, MT_CONTROL);
        }
}