1 /*- 2 * Copyright (c) 2002 Tim J. Robbins. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: /src/usr.bin/newgrp/newgrp.c,v 1.2 2003/10/30 15:14:34 harti Exp $ 27 * $DragonFly: src/usr.bin/newgrp/newgrp.c,v 1.3 2004/12/08 22:26:42 liamfoy Exp $ 28 */ 29 30 /* 31 * newgrp -- change to a new group 32 */ 33 34 #include <sys/types.h> 35 36 #include <err.h> 37 #include <errno.h> 38 #include <grp.h> 39 #include <libgen.h> 40 #include <limits.h> 41 #include <login_cap.h> 42 #include <paths.h> 43 #include <pwd.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 49 static void addgroup(const char *grpname); 50 static void doshell(void); 51 static int inarray(gid_t, const gid_t[], int); 52 static void loginshell(void); 53 static void restoregrps(void); 54 static void usage(void); 55 56 static struct passwd *pwd; 57 static uid_t euid; 58 59 extern char **environ; 60 61 /* Manipulate effective user ID. */ 62 #define PRIV_START do { \ 63 if (seteuid(euid) < 0) \ 64 err(1, "seteuid"); \ 65 } while (0) 66 #define PRIV_END do { \ 67 if (seteuid(getuid()) < 0) \ 68 err(1, "seteuid"); \ 69 } while (0) 70 71 int 72 main(int argc, char *argv[]) 73 { 74 int ch, login; 75 76 euid = geteuid(); 77 if (seteuid(getuid()) < 0) 78 err(1, "seteuid"); 79 80 if ((pwd = getpwuid(getuid())) == NULL) 81 errx(1, "unknown user"); 82 83 login = 0; 84 while ((ch = getopt(argc, argv, "-l")) != -1) { 85 switch (ch) { 86 case '-': /* Obsolescent */ 87 case 'l': 88 login = 1; 89 break; 90 default: 91 usage(); 92 } 93 } 94 argc -= optind; 95 argv += optind; 96 97 switch (argc) { 98 case 0: 99 restoregrps(); 100 break; 101 case 1: 102 addgroup(*argv); 103 break; 104 default: 105 usage(); 106 } 107 108 if (seteuid(euid) < 0) 109 err(1, "seteuid"); 110 if (setuid(getuid()) < 0) 111 err(1, "setuid"); 112 113 if (login) 114 loginshell(); 115 else 116 doshell(); 117 118 /*NOTREACHED*/ 119 exit(1); 120 } 121 122 static void 123 usage(void) 124 { 125 126 fprintf(stderr, "usage: newgrp [-l] [group]\n"); 127 exit(1); 128 } 129 130 static void 131 restoregrps(void) 132 { 133 int initres, setres; 134 135 PRIV_START; 136 initres = initgroups(pwd->pw_name, pwd->pw_gid); 137 setres = setgid(pwd->pw_gid); 138 PRIV_END; 139 140 if (initres < 0) 141 warn("initgroups"); 142 if (setres < 0) 143 warn("setgroups"); 144 } 145 146 static void 147 addgroup(const char *grpname) 148 { 149 gid_t grps[NGROUPS_MAX]; 150 long lgid; 151 int dbmember, i, ngrps; 152 gid_t egid; 153 struct group *grp; 154 char *ep, *pass, *cryptpw; 155 char **p; 156 157 egid = getegid(); 158 159 /* Try it as a group name, then a group id. */ 160 if ((grp = getgrnam(grpname)) == NULL) 161 if ((lgid = strtol(grpname, &ep, 10)) <= 0 || *ep != '\0' || 162 (grp = getgrgid((gid_t)lgid)) == NULL ) { 163 warnx("%s: bad group name", grpname); 164 return; 165 } 166 167 /* 168 * If the user is not a member of the requested group and the group 169 * has a password, prompt and check it. 170 */ 171 dbmember = 0; 172 if (pwd->pw_gid == grp->gr_gid) 173 dbmember = 1; 174 for (p = grp->gr_mem; *p != NULL; p++) 175 if (strcmp(*p, pwd->pw_name) == 0) { 176 dbmember = 1; 177 break; 178 } 179 if (!dbmember && *grp->gr_passwd != '\0' && getuid() != 0) { 180 pass = getpass("Password:"); 181 if (pass == NULL) 182 return; 183 cryptpw = crypt(pass, grp->gr_passwd); 184 if (cryptpw == NULL || strcmp(grp->gr_passwd, cryptpw) != 0) { 185 fprintf(stderr, "Sorry\n"); 186 return; 187 } 188 } 189 190 if ((ngrps = getgroups(NGROUPS_MAX, (gid_t *)grps)) < 0) { 191 warn("getgroups"); 192 return; 193 } 194 195 /* Remove requested gid from supp. list if it exists. */ 196 if (grp->gr_gid != egid && inarray(grp->gr_gid, grps, ngrps)) { 197 for (i = 0; i < ngrps; i++) 198 if (grps[i] == grp->gr_gid) 199 break; 200 ngrps--; 201 memmove(&grps[i], &grps[i + 1], (ngrps - i) * sizeof(gid_t)); 202 PRIV_START; 203 if (setgroups(ngrps, (const gid_t *)grps) < 0) { 204 PRIV_END; 205 warn("setgroups"); 206 return; 207 } 208 PRIV_END; 209 } 210 211 PRIV_START; 212 if (setgid(grp->gr_gid)) { 213 PRIV_END; 214 warn("setgid"); 215 return; 216 } 217 PRIV_END; 218 grps[0] = grp->gr_gid; 219 220 /* Add old effective gid to supp. list if it does not exist. */ 221 if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) { 222 if (ngrps == NGROUPS_MAX) 223 warnx("too many groups"); 224 else { 225 grps[ngrps++] = egid; 226 PRIV_START; 227 if (setgroups(ngrps, (const gid_t *)grps)) { 228 PRIV_END; 229 warn("setgroups"); 230 return; 231 } 232 PRIV_END; 233 } 234 } 235 236 } 237 238 static int 239 inarray(gid_t gid, const gid_t grps[], int ngrps) 240 { 241 int i; 242 243 for (i = 0; i < ngrps; i++) 244 if (grps[i] == gid) 245 return (1); 246 return (0); 247 } 248 249 /* 250 * Set the environment to what would be expected if the user logged in 251 * again; this performs the same steps as su(1)'s -l option. 252 */ 253 static void 254 loginshell(void) 255 { 256 char *args[2], **cleanenv, *term, *ticket; 257 const char *shell; 258 login_cap_t *lc; 259 260 shell = pwd->pw_shell; 261 if (*shell == '\0') 262 shell = _PATH_BSHELL; 263 if (chdir(pwd->pw_dir) < 0) { 264 warn("%s", pwd->pw_dir); 265 chdir("/"); 266 } 267 268 term = getenv("TERM"); 269 ticket = getenv("KRBTKFILE"); 270 271 if ((cleanenv = calloc(20, sizeof(char *))) == NULL) 272 err(1, "calloc"); 273 *cleanenv = NULL; 274 environ = cleanenv; 275 276 lc = login_getpwclass(pwd); 277 setusercontext(lc, pwd, pwd->pw_uid, 278 LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV); 279 login_close(lc); 280 if (setenv("USER", pwd->pw_name, 1) == -1) 281 err(EXIT_FAILURE, "setenv failed"); 282 283 if (setenv("SHELL", shell, 1) == -1) 284 err(EXIT_FAILURE, "setenv failed"); 285 286 if (setenv("HOME", pwd->pw_dir, 1) == -1) 287 err(EXIT_FAILURE, "setenv failed"); 288 289 if (term != NULL) 290 if (setenv("TERM", term, 1) == -1) 291 err(EXIT_FAILURE, "setenv failed"); 292 if (ticket != NULL) 293 if (setenv("KRBTKFILE", ticket, 1) == -1) 294 err(EXIT_FAILURE, "setenv failed"); 295 296 if (asprintf(args, "-%s", basename(shell)) < 0) 297 err(1, "asprintf"); 298 args[1] = NULL; 299 300 execv(shell, args); 301 err(1, "%s", shell); 302 } 303 304 static void 305 doshell(void) 306 { 307 const char *shell; 308 309 shell = pwd->pw_shell; 310 if (*shell == '\0') 311 shell = _PATH_BSHELL; 312 execl(shell, basename(shell), NULL); 313 err(1, "%s", shell); 314 } 315