1 | /* $OpenBSD: rcmdsh.c,v 1.5 1998/04/25 16:23:58 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 | |
---|
31 | /* |
---|
32 | * This is an rcmd() replacement originally by |
---|
33 | * Chris Siebenmann <cks@utcc.utoronto.ca>. |
---|
34 | */ |
---|
35 | |
---|
36 | #include <sys/cdefs.h> |
---|
37 | #include <sys/types.h> |
---|
38 | #include <machine/endian.h> |
---|
39 | |
---|
40 | #include <sys/types.h> |
---|
41 | #include <sys/socket.h> |
---|
42 | #include <sys/wait.h> |
---|
43 | |
---|
44 | #include <errno.h> |
---|
45 | #include <netdb.h> |
---|
46 | #include <paths.h> |
---|
47 | #include <pwd.h> |
---|
48 | #include <stdio.h> |
---|
49 | #include <string.h> |
---|
50 | #include <unistd.h> |
---|
51 | |
---|
52 | #ifndef _PATH_RSH |
---|
53 | #define _PATH_RSH "/usr/bin/rsh" |
---|
54 | #endif |
---|
55 | |
---|
56 | /* |
---|
57 | * This is a replacement rcmd() function that uses the rsh(1) |
---|
58 | * program in place of a direct rcmd(3) function call so as to |
---|
59 | * avoid having to be root. Note that rport is ignored. |
---|
60 | */ |
---|
61 | int |
---|
62 | rcmdsh(ahost, rport, locuser, remuser, cmd, rshprog) |
---|
63 | char **ahost; |
---|
64 | int rport; |
---|
65 | const char *locuser, *remuser, *cmd, *rshprog; |
---|
66 | { |
---|
67 | struct addrinfo hints, *res; |
---|
68 | int cpid, sp[2], error; |
---|
69 | char *p; |
---|
70 | struct passwd *pw; |
---|
71 | char num[8]; |
---|
72 | static char hbuf[NI_MAXHOST]; |
---|
73 | |
---|
74 | /* What rsh/shell to use. */ |
---|
75 | if (rshprog == NULL) |
---|
76 | rshprog = _PATH_RSH; |
---|
77 | |
---|
78 | /* locuser must exist on this host. */ |
---|
79 | if ((pw = getpwnam(locuser)) == NULL) { |
---|
80 | (void)fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser); |
---|
81 | return (-1); |
---|
82 | } |
---|
83 | |
---|
84 | /* Validate remote hostname. */ |
---|
85 | if (strcmp(*ahost, "localhost") != 0) { |
---|
86 | memset(&hints, 0, sizeof(hints)); |
---|
87 | hints.ai_flags = AI_CANONNAME; |
---|
88 | hints.ai_family = PF_UNSPEC; |
---|
89 | hints.ai_socktype = SOCK_STREAM; |
---|
90 | (void)snprintf(num, sizeof(num), "%d", ntohs(rport)); |
---|
91 | error = getaddrinfo(*ahost, num, &hints, &res); |
---|
92 | if (error) { |
---|
93 | fprintf(stderr, "rcmdsh: getaddrinfo: %s\n", |
---|
94 | gai_strerror(error)); |
---|
95 | return (-1); |
---|
96 | } |
---|
97 | if (res->ai_canonname) { |
---|
98 | strncpy(hbuf, res->ai_canonname, sizeof(hbuf) - 1); |
---|
99 | hbuf[sizeof(hbuf) - 1] = '\0'; |
---|
100 | *ahost = hbuf; |
---|
101 | } |
---|
102 | freeaddrinfo(res); |
---|
103 | } |
---|
104 | |
---|
105 | /* Get a socketpair we'll use for stdin and stdout. */ |
---|
106 | if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) == -1) { |
---|
107 | perror("rcmdsh: socketpair"); |
---|
108 | return (-1); |
---|
109 | } |
---|
110 | |
---|
111 | cpid = fork(); |
---|
112 | if (cpid == -1) { |
---|
113 | perror("rcmdsh: fork failed"); |
---|
114 | return (-1); |
---|
115 | } else if (cpid == 0) { |
---|
116 | /* |
---|
117 | * Child. We use sp[1] to be stdin/stdout, and close sp[0]. |
---|
118 | */ |
---|
119 | (void)close(sp[0]); |
---|
120 | if (dup2(sp[1], 0) == -1 || dup2(0, 1) == -1) { |
---|
121 | perror("rcmdsh: dup2 failed"); |
---|
122 | _exit(255); |
---|
123 | } |
---|
124 | /* Fork again to lose parent. */ |
---|
125 | cpid = fork(); |
---|
126 | if (cpid == -1) { |
---|
127 | perror("rcmdsh: fork to lose parent failed"); |
---|
128 | _exit(255); |
---|
129 | } |
---|
130 | if (cpid > 0) |
---|
131 | _exit(0); |
---|
132 | |
---|
133 | /* In grandchild here. Become local user for rshprog. */ |
---|
134 | if (setuid(pw->pw_uid) == -1) { |
---|
135 | (void)fprintf(stderr, "rcmdsh: setuid(%u): %s\n", |
---|
136 | pw->pw_uid, strerror(errno)); |
---|
137 | _exit(255); |
---|
138 | } |
---|
139 | |
---|
140 | /* |
---|
141 | * If remote host is "localhost" and local and remote users |
---|
142 | * are the same, avoid running remote shell for efficiency. |
---|
143 | */ |
---|
144 | if (strcmp(*ahost, "localhost") == 0 && |
---|
145 | strcmp(locuser, remuser) == 0) { |
---|
146 | if (pw->pw_shell[0] == '\0') |
---|
147 | rshprog = _PATH_BSHELL; |
---|
148 | else |
---|
149 | rshprog = pw->pw_shell; |
---|
150 | p = strrchr(rshprog, '/'); |
---|
151 | execlp(rshprog, p ? p + 1 : rshprog, "-c", cmd, |
---|
152 | (char *)NULL); |
---|
153 | } else { |
---|
154 | p = strrchr(rshprog, '/'); |
---|
155 | execlp(rshprog, p ? p + 1 : rshprog, *ahost, "-l", |
---|
156 | remuser, cmd, (char *)NULL); |
---|
157 | } |
---|
158 | (void)fprintf(stderr, "rcmdsh: execlp %s failed: %s\n", |
---|
159 | rshprog, strerror(errno)); |
---|
160 | _exit(255); |
---|
161 | } else { |
---|
162 | /* Parent. close sp[1], return sp[0]. */ |
---|
163 | (void)close(sp[1]); |
---|
164 | /* Reap child. */ |
---|
165 | (void)wait(NULL); |
---|
166 | return (sp[0]); |
---|
167 | } |
---|
168 | /* NOTREACHED */ |
---|
169 | } |
---|