ed36b0a2 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: chrootsh.c,v 1.1 1999/04/20 00:19:04 mdw Exp $ |
4 | * |
5 | * Chroot gaol shell |
6 | * |
7 | * (c) 1999 EBI |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Chroot shell. |
13 | * |
14 | * chrootsh is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * chrootsh is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with chrootsh; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: chrootsh.c,v $ |
32 | * Revision 1.1 1999/04/20 00:19:04 mdw |
33 | * Initial revision |
34 | * |
35 | */ |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include <errno.h> |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | |
44 | #include <sys/types.h> |
45 | #include <unistd.h> |
46 | #include <pwd.h> |
47 | |
48 | extern char **environ; |
49 | |
50 | /*----- Main code ---------------------------------------------------------*/ |
51 | |
52 | #ifndef CHROOTSH_PATH |
53 | # define CHROOTSH_PATH "/usr/bin/chrootsh" |
54 | #endif |
55 | |
56 | static const char *quis = "chrootsh"; |
57 | |
58 | static void *xmalloc(size_t sz) |
59 | { |
60 | void *p = malloc(sz); |
61 | if (!p) { |
62 | fprintf(stderr, "%s: not enough memory\n", quis); |
63 | exit(EXIT_FAILURE); |
64 | } |
65 | return (p); |
66 | } |
67 | |
68 | static char *xstrdup(const char *p) |
69 | { |
70 | size_t sz = strlen(p) + 1; |
71 | char *q = xmalloc(sz); |
72 | memcpy(q, p, sz); |
73 | return (q); |
74 | } |
75 | |
76 | int main(int argc, char *argv[]) |
77 | { |
78 | struct passwd *pw; |
79 | uid_t me = getuid(); |
80 | char **env; |
81 | char **av; |
82 | |
83 | /* --- Resolve the program name --- */ |
84 | |
85 | { |
86 | char *p, *q; |
87 | p = argv[0]; |
88 | for (q = argv[0]; *q; q++) { |
89 | if (*q == '/') |
90 | p = q + 1; |
91 | } |
92 | quis = p; |
93 | } |
94 | |
95 | /* --- Check the user is meant to be chrooted --- */ |
96 | |
97 | pw = getpwuid(me); |
98 | if (!pw) { |
99 | fprintf(stderr, "%s: you don't exist. Go away.\n", quis); |
100 | exit(EXIT_FAILURE); |
101 | } |
102 | if (strcmp(pw->pw_shell, CHROOTSH_PATH) != 0) { |
103 | fprintf(stderr, "%s: you aren't a chrooted user\n", quis); |
104 | exit(EXIT_FAILURE); |
105 | } |
106 | endpwent(); |
107 | |
108 | /* --- Chroot the user --- */ |
109 | |
110 | { |
111 | char *p = xstrdup(pw->pw_dir); |
112 | char *q = strstr(p, "/./"); |
113 | if (q) |
114 | *q = 0; |
115 | |
116 | if (chdir(p) || chroot(p)) { |
117 | fprintf(stderr, "%s: couldn't call chroot: %s", quis, strerror(errno)); |
118 | exit(EXIT_FAILURE); |
119 | } |
120 | setuid(me); |
121 | free(p); |
122 | } |
123 | |
124 | /* --- Read the new password block --- */ |
125 | |
126 | { |
127 | char *p = xstrdup(pw->pw_name); |
128 | pw = getpwnam(p); |
129 | free(p); |
130 | if (!pw) { |
131 | fprintf(stderr, "%s: you don't exist in the gaol\n", quis); |
132 | exit(EXIT_FAILURE); |
133 | } |
134 | endpwent(); |
135 | } |
136 | |
137 | /* --- Now fiddle with environment strings and suchlike --- */ |
138 | |
139 | { |
140 | size_t n; |
141 | for (n = 0; environ[n]; n++) |
142 | ; |
143 | env = xmalloc((n + 1) * sizeof(char *)); |
144 | |
145 | for (n = 0; environ[n]; n++) { |
146 | if (strncmp(environ[n], "HOME=", 5) == 0) { |
147 | char *p = xmalloc(6 + strlen(pw->pw_dir)); |
148 | sprintf(p, "HOME=%s", pw->pw_dir); |
149 | env[n] = p; |
150 | } else if (strncmp(environ[n], "SHELL=", 6) == 0) { |
151 | char *p = xmalloc(7 + strlen(pw->pw_shell)); |
152 | sprintf(p, "SHELL=%s", pw->pw_shell); |
153 | env[n] = p; |
154 | } else |
155 | env[n] = environ[n]; |
156 | } |
157 | env[n] = 0; |
158 | } |
159 | |
160 | /* --- Finally, sort the argument list --- */ |
161 | |
162 | { |
163 | char *p, *q; |
164 | int i; |
165 | |
166 | av = xmalloc((argc + 1) * sizeof(char *)); |
167 | p = pw->pw_shell; |
168 | for (q = p; *q; q++) { |
169 | if (*q == '/') |
170 | p = q + 1; |
171 | } |
172 | if (argv[0][0] == '-') { |
173 | q = xmalloc(2 + strlen(p)); |
174 | *q = '-'; |
175 | strcpy(q + 1, p); |
176 | av[0] = q; |
177 | } else |
178 | av[0] = p; |
179 | |
180 | for (i = 1; i <= argc; i++) |
181 | av[i] = argv[i]; |
182 | } |
183 | |
184 | /* --- Change directory (again) --- */ |
185 | |
186 | if (chdir(pw->pw_dir)) |
187 | fprintf(stderr, "No directory, logging in with HOME=/\n"); |
188 | |
189 | /* --- Run the real shell --- */ |
190 | |
191 | execve(pw->pw_shell, av, env); |
192 | fprintf(stderr, "%s: couldn't exec `%s': %s", |
193 | quis, pw->pw_shell, strerror(errno)); |
194 | return (EXIT_FAILURE); |
195 | } |
196 | |
197 | /*----- That's all, folks -------------------------------------------------*/ |