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      1 /* $OpenBSD: monitor_fdpass.c,v 1.21 2016/02/29 20:22:36 jca Exp $ */
      2 /*
      3  * Copyright 2001 Niels Provos <provos (at) citi.umich.edu>
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 #include "includes.h"
     28 
     29 #include <sys/types.h>
     30 #include <sys/socket.h>
     31 #include <sys/uio.h>
     32 #ifdef HAVE_SYS_UN_H
     33 #include <sys/un.h>
     34 #endif
     35 
     36 #include <errno.h>
     37 #include <string.h>
     38 #include <stdarg.h>
     39 
     40 #ifdef HAVE_POLL_H
     41 # include <poll.h>
     42 #else
     43 # ifdef HAVE_SYS_POLL_H
     44 #  include <sys/poll.h>
     45 # endif
     46 #endif
     47 
     48 #include "log.h"
     49 #include "monitor_fdpass.h"
     50 
     51 int
     52 mm_send_fd(int sock, int fd)
     53 {
     54 #if defined(HAVE_SENDMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
     55 	struct msghdr msg;
     56 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR
     57 	union {
     58 		struct cmsghdr hdr;
     59 		char buf[CMSG_SPACE(sizeof(int))];
     60 	} cmsgbuf;
     61 	struct cmsghdr *cmsg;
     62 #endif
     63 	struct iovec vec;
     64 	char ch = '\0';
     65 	ssize_t n;
     66 	struct pollfd pfd;
     67 
     68 	memset(&msg, 0, sizeof(msg));
     69 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
     70 	msg.msg_accrights = (caddr_t)&fd;
     71 	msg.msg_accrightslen = sizeof(fd);
     72 #else
     73 	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
     74 	msg.msg_control = (caddr_t)&cmsgbuf.buf;
     75 	msg.msg_controllen = sizeof(cmsgbuf.buf);
     76 	cmsg = CMSG_FIRSTHDR(&msg);
     77 	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
     78 	cmsg->cmsg_level = SOL_SOCKET;
     79 	cmsg->cmsg_type = SCM_RIGHTS;
     80 	*(int *)CMSG_DATA(cmsg) = fd;
     81 #endif
     82 
     83 	vec.iov_base = &ch;
     84 	vec.iov_len = 1;
     85 	msg.msg_iov = &vec;
     86 	msg.msg_iovlen = 1;
     87 
     88 	pfd.fd = sock;
     89 	pfd.events = POLLOUT;
     90 	while ((n = sendmsg(sock, &msg, 0)) == -1 &&
     91 	    (errno == EAGAIN || errno == EINTR)) {
     92 		debug3("%s: sendmsg(%d): %s", __func__, fd, strerror(errno));
     93 		(void)poll(&pfd, 1, -1);
     94 	}
     95 	if (n == -1) {
     96 		error("%s: sendmsg(%d): %s", __func__, fd,
     97 		    strerror(errno));
     98 		return -1;
     99 	}
    100 
    101 	if (n != 1) {
    102 		error("%s: sendmsg: expected sent 1 got %zd", __func__, n);
    103 		return -1;
    104 	}
    105 	return 0;
    106 #else
    107 	error("%s: file descriptor passing not supported", __func__);
    108 	return -1;
    109 #endif
    110 }
    111 
    112 int
    113 mm_receive_fd(int sock)
    114 {
    115 #if defined(HAVE_RECVMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
    116 	struct msghdr msg;
    117 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR
    118 	union {
    119 		struct cmsghdr hdr;
    120 		char buf[CMSG_SPACE(sizeof(int))];
    121 	} cmsgbuf;
    122 	struct cmsghdr *cmsg;
    123 #endif
    124 	struct iovec vec;
    125 	ssize_t n;
    126 	char ch;
    127 	int fd;
    128 	struct pollfd pfd;
    129 
    130 	memset(&msg, 0, sizeof(msg));
    131 	vec.iov_base = &ch;
    132 	vec.iov_len = 1;
    133 	msg.msg_iov = &vec;
    134 	msg.msg_iovlen = 1;
    135 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
    136 	msg.msg_accrights = (caddr_t)&fd;
    137 	msg.msg_accrightslen = sizeof(fd);
    138 #else
    139 	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
    140 	msg.msg_control = &cmsgbuf.buf;
    141 	msg.msg_controllen = sizeof(cmsgbuf.buf);
    142 #endif
    143 
    144 	pfd.fd = sock;
    145 	pfd.events = POLLIN;
    146 	while ((n = recvmsg(sock, &msg, 0)) == -1 &&
    147 	    (errno == EAGAIN || errno == EINTR)) {
    148 		debug3("%s: recvmsg: %s", __func__, strerror(errno));
    149 		(void)poll(&pfd, 1, -1);
    150 	}
    151 	if (n == -1) {
    152 		error("%s: recvmsg: %s", __func__, strerror(errno));
    153 		return -1;
    154 	}
    155 
    156 	if (n != 1) {
    157 		error("%s: recvmsg: expected received 1 got %zd", __func__, n);
    158 		return -1;
    159 	}
    160 
    161 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
    162 	if (msg.msg_accrightslen != sizeof(fd)) {
    163 		error("%s: no fd", __func__);
    164 		return -1;
    165 	}
    166 #else
    167 	cmsg = CMSG_FIRSTHDR(&msg);
    168 	if (cmsg == NULL) {
    169 		error("%s: no message header", __func__);
    170 		return -1;
    171 	}
    172 
    173 #ifndef BROKEN_CMSG_TYPE
    174 	if (cmsg->cmsg_type != SCM_RIGHTS) {
    175 		error("%s: expected type %d got %d", __func__,
    176 		    SCM_RIGHTS, cmsg->cmsg_type);
    177 		return -1;
    178 	}
    179 #endif
    180 	fd = (*(int *)CMSG_DATA(cmsg));
    181 #endif
    182 	return fd;
    183 #else
    184 	error("%s: file descriptor passing not supported", __func__);
    185 	return -1;
    186 #endif
    187 }
    188