1 /* $OpenBSD: rcmdsh.c,v 1.7 2002/03/12 00:05:44 millert Exp $ */ 2 3 /* 4 * Copyright (c) 2001, MagniComp 5 * 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 14 * the documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the MagniComp nor the names of its contributors may 16 * be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 20 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR 23 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 25 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 26 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 27 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 28 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * 30 * $FreeBSD: src/lib/libc/net/rcmdsh.c,v 1.3.2.2 2002/04/22 17:38:53 ume Exp $ 31 * $DragonFly: src/lib/libc/net/rcmdsh.c,v 1.4 2005/11/13 02:04:47 swildner Exp $ 32 */ 33 34 /* 35 * This is an rcmd() replacement originally by 36 * Chris Siebenmann <cks@utcc.utoronto.ca>. 37 */ 38 39 #include <sys/types.h> 40 #include <sys/socket.h> 41 #include <sys/wait.h> 42 43 #include <errno.h> 44 #include <netdb.h> 45 #include <paths.h> 46 #include <pwd.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #ifndef _PATH_RSH 52 #define _PATH_RSH "/usr/bin/rsh" 53 #endif 54 55 /* 56 * This is a replacement rcmd() function that uses the rsh(1) 57 * program in place of a direct rcmd(3) function call so as to 58 * avoid having to be root. Note that rport is ignored. 59 */ 60 int 61 rcmdsh(char **ahost, int rport, const char *locuser, const char *remuser, 62 const char *cmd, const char *rshprog) 63 { 64 struct addrinfo hints, *res; 65 int sp[2], error; 66 pid_t cpid; 67 char *p; 68 struct passwd *pw; 69 char num[8]; 70 static char hbuf[NI_MAXHOST]; 71 72 /* What rsh/shell to use. */ 73 if (rshprog == NULL) 74 rshprog = _PATH_RSH; 75 76 /* locuser must exist on this host. */ 77 if ((pw = getpwnam(locuser)) == NULL) { 78 fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser); 79 return (-1); 80 } 81 82 /* Validate remote hostname. */ 83 if (strcmp(*ahost, "localhost") != 0) { 84 memset(&hints, 0, sizeof(hints)); 85 hints.ai_flags = AI_CANONNAME; 86 hints.ai_family = PF_UNSPEC; 87 hints.ai_socktype = SOCK_STREAM; 88 snprintf(num, sizeof(num), "%d", ntohs(rport)); 89 error = getaddrinfo(*ahost, num, &hints, &res); 90 if (error) { 91 fprintf(stderr, "rcmdsh: getaddrinfo: %s\n", 92 gai_strerror(error)); 93 return (-1); 94 } 95 if (res->ai_canonname) { 96 strncpy(hbuf, res->ai_canonname, sizeof(hbuf) - 1); 97 hbuf[sizeof(hbuf) - 1] = '\0'; 98 *ahost = hbuf; 99 } 100 freeaddrinfo(res); 101 } 102 103 /* Get a socketpair we'll use for stdin and stdout. */ 104 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) == -1) { 105 perror("rcmdsh: socketpair"); 106 return (-1); 107 } 108 109 cpid = fork(); 110 if (cpid == -1) { 111 perror("rcmdsh: fork failed"); 112 return (-1); 113 } else if (cpid == 0) { 114 /* 115 * Child. We use sp[1] to be stdin/stdout, and close sp[0]. 116 */ 117 close(sp[0]); 118 if (dup2(sp[1], 0) == -1 || dup2(0, 1) == -1) { 119 perror("rcmdsh: dup2 failed"); 120 _exit(255); 121 } 122 /* Fork again to lose parent. */ 123 cpid = fork(); 124 if (cpid == -1) { 125 perror("rcmdsh: fork to lose parent failed"); 126 _exit(255); 127 } 128 if (cpid > 0) 129 _exit(0); 130 131 /* In grandchild here. Become local user for rshprog. */ 132 if (setuid(pw->pw_uid) == -1) { 133 fprintf(stderr, "rcmdsh: setuid(%u): %s\n", 134 pw->pw_uid, strerror(errno)); 135 _exit(255); 136 } 137 138 /* 139 * If remote host is "localhost" and local and remote users 140 * are the same, avoid running remote shell for efficiency. 141 */ 142 if (strcmp(*ahost, "localhost") == 0 && 143 strcmp(locuser, remuser) == 0) { 144 if (pw->pw_shell[0] == '\0') 145 rshprog = _PATH_BSHELL; 146 else 147 rshprog = pw->pw_shell; 148 p = strrchr(rshprog, '/'); 149 execlp(rshprog, p ? p + 1 : rshprog, "-c", cmd, 150 (char *)NULL); 151 } else { 152 p = strrchr(rshprog, '/'); 153 execlp(rshprog, p ? p + 1 : rshprog, *ahost, "-l", 154 remuser, cmd, (char *)NULL); 155 } 156 fprintf(stderr, "rcmdsh: execlp %s failed: %s\n", 157 rshprog, strerror(errno)); 158 _exit(255); 159 } else { 160 /* Parent. close sp[1], return sp[0]. */ 161 close(sp[1]); 162 /* Reap child. */ 163 wait(NULL); 164 return (sp[0]); 165 } 166 /* NOTREACHED */ 167 } 168