1 /* $OpenBSD: bindresvport.c,v 1.19 2019/06/28 13:32:42 deraadt Exp $ */ 2 3 /* 4 * Copyright 1996, Jason Downs. All rights reserved. 5 * Copyright 1998, Theo de Raadt. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <errno.h> 29 #include <string.h> 30 #include <sys/types.h> 31 #include <sys/socket.h> 32 #include <netinet/in.h> 33 34 /* 35 * Bind a socket to a privileged IP port 36 */ 37 int 38 bindresvport(int sd, struct sockaddr_in *sin) 39 { 40 return bindresvport_sa(sd, (struct sockaddr *)sin); 41 } 42 DEF_WEAK(bindresvport); 43 44 /* 45 * Bind a socket to a privileged port for whatever protocol. 46 */ 47 int 48 bindresvport_sa(int sd, struct sockaddr *sa) 49 { 50 int old, error, af; 51 struct sockaddr_storage myaddr; 52 struct sockaddr_in *sin; 53 struct sockaddr_in6 *sin6; 54 int proto, portrange, portlow; 55 u_int16_t port; 56 socklen_t salen; 57 58 if (sa == NULL) { 59 salen = sizeof(myaddr); 60 sa = (struct sockaddr *)&myaddr; 61 62 if (getsockname(sd, sa, &salen) == -1) 63 return -1; /* errno is correctly set */ 64 65 af = sa->sa_family; 66 memset(&myaddr, 0, salen); 67 } else 68 af = sa->sa_family; 69 70 if (af == AF_INET) { 71 proto = IPPROTO_IP; 72 portrange = IP_PORTRANGE; 73 portlow = IP_PORTRANGE_LOW; 74 sin = (struct sockaddr_in *)sa; 75 salen = sizeof(struct sockaddr_in); 76 port = sin->sin_port; 77 } else if (af == AF_INET6) { 78 proto = IPPROTO_IPV6; 79 portrange = IPV6_PORTRANGE; 80 portlow = IPV6_PORTRANGE_LOW; 81 sin6 = (struct sockaddr_in6 *)sa; 82 salen = sizeof(struct sockaddr_in6); 83 port = sin6->sin6_port; 84 } else { 85 errno = EPFNOSUPPORT; 86 return (-1); 87 } 88 sa->sa_family = af; 89 sa->sa_len = salen; 90 91 if (port == 0) { 92 socklen_t oldlen = sizeof(old); 93 94 error = getsockopt(sd, proto, portrange, &old, &oldlen); 95 if (error == -1) 96 return (error); 97 98 error = setsockopt(sd, proto, portrange, &portlow, 99 sizeof(portlow)); 100 if (error == -1) 101 return (error); 102 } 103 104 error = bind(sd, sa, salen); 105 106 if (port == 0) { 107 int saved_errno = errno; 108 109 if (error) { 110 if (setsockopt(sd, proto, portrange, &old, 111 sizeof(old)) == -1) 112 errno = saved_errno; 113 return (error); 114 } 115 116 if (sa != (struct sockaddr *)&myaddr) { 117 /* Hmm, what did the kernel assign... */ 118 if (getsockname(sd, sa, &salen) == -1) 119 errno = saved_errno; 120 return (error); 121 } 122 } 123 return (error); 124 } 125 DEF_WEAK(bindresvport_sa); 126