system_cmds-597.1.1/newgrp.tproj/newgrp.c

   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
  27 /*
  28  * newgrp -- change to a new group
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD: src/usr.bin/newgrp/newgrp.c,v 1.5 2009/12/13 03:14:06 delphij Exp $");
  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 #ifndef __APPLE__
  42 #include <login_cap.h>
  43 #endif /* !__APPLE__ */
  44 #ifdef __APPLE__
  45 #include <membership.h>
  46 #endif /* __APPLE__ */
  47 #include <pwd.h>
  48 #include <stdio.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <unistd.h>
  52 #ifdef __APPLE__
  53 #include <paths.h>
  54 #endif /* __APPLE__ */
  55 static void      addgroup(const char *grpname);
  56 static void      doshell(void);
  57 static int       inarray(gid_t, const gid_t[], int);
  58 static void      loginshell(void);
  59 static void      restoregrps(void);
  60 static void      usage(void);
  61
  62 static struct passwd *pwd;
  63 static uid_t euid;
  64
  65 extern char **environ;
  66
  67 /* Manipulate effective user ID. */
  68 #define PRIV_START do {                         \
  69                 if (seteuid(euid) < 0)          \
  70                         err(1, "seteuid");      \
  71         } while (0)
  72 #define PRIV_END do {                           \
  73                 if (seteuid(getuid()) < 0)      \
  74                         err(1, "seteuid");      \
  75         } while (0)
  76
  77 int
  78 main(int argc, char *argv[])
  79 {
  80         int ch, login;
  81
  82         euid = geteuid();
  83         if (seteuid(getuid()) < 0)
  84                 err(1, "seteuid");
  85
  86         if ((pwd = getpwuid(getuid())) == NULL)
  87                 errx(1, "unknown user");
  88
  89         login = 0;
  90         while ((ch = getopt(argc, argv, "-l")) != -1) {
  91                 switch (ch) {
  92                 case '-':               /* Obsolescent */
  93                 case 'l':
  94                         login = 1;
  95                         break;
  96                 default:
  97                         usage();
  98                 }
  99         }
 100         argc -= optind;
 101         argv += optind;
 102
 103         switch (argc) {
 104         case 0:
 105                 restoregrps();
 106                 break;
 107         case 1:
 108                 addgroup(*argv);
 109                 break;
 110         default:
 111                 usage();
 112         }
 113
 114         if (seteuid(euid) < 0)
 115                 err(1, "seteuid");
 116         if (setuid(getuid()) < 0)
 117                 err(1, "setuid");
 118
 119         if (login)
 120                 loginshell();
 121         else
 122                 doshell();
 123
 124         /*NOTREACHED*/
 125         exit(1);
 126 }
 127
 128 static void
 129 usage(void)
 130 {
 131
 132         fprintf(stderr, "usage: newgrp [-l] [group]\n");
 133         exit(1);
 134 }
 135
 136 static void
 137 restoregrps(void)
 138 {
 139         int initres, setres;
 140
 141         PRIV_START;
 142         initres = initgroups(pwd->pw_name, pwd->pw_gid);
 143         setres = setgid(pwd->pw_gid);
 144         PRIV_END;
 145
 146         if (initres < 0)
 147                 warn("initgroups");
 148         if (setres < 0)
 149                 warn("setgid");
 150 }
 151
 152 static void
 153 addgroup(const char *grpname)
 154 {
 155         gid_t *grps;
 156         long lgid, ngrps_max;
 157         int dbmember, i, ngrps;
 158         gid_t egid;
 159         struct group *grp;
 160         char *ep, *pass;
 161         char **p;
 162         char *grp_passwd;
 163 #ifdef __APPLE__
 164         uuid_t user_uuid;
 165         uuid_t group_uuid;
 166         int status;
 167 #endif
 168
 169         egid = getegid();
 170
 171         /* Try it as a group name, then a group id. */
 172         if ((grp = getgrnam(grpname)) == NULL)
 173                 if ((lgid = strtol(grpname, &ep, 10)) <= 0 || *ep != '\0' ||
 174                     (grp = getgrgid((gid_t)lgid)) == NULL ) {
 175                         warnx("%s: bad group name", grpname);
 176                         return;
 177                 }
 178
 179 #ifdef __APPLE__
 180         status = mbr_uid_to_uuid(pwd->pw_uid, user_uuid);
 181         if (status)
 182                 errc(1, status, "mbr_uid_to_uuid");
 183
 184         status = mbr_gid_to_uuid(grp->gr_gid, group_uuid);
 185         if (status)
 186                 errc(1, status, "mbr_gid_to_uuid");
 187
 188         status = mbr_check_membership(user_uuid, group_uuid, &dbmember);
 189         if (status)
 190                 errc(1, status, "mbr_check_membership");
 191 #else
 192         /*
 193          * If the user is not a member of the requested group and the group
 194          * has a password, prompt and check it.
 195          */
 196         dbmember = 0;
 197         if (pwd->pw_gid == grp->gr_gid)
 198                 dbmember = 1;
 199         for (p = grp->gr_mem; *p != NULL; p++)
 200                 if (strcmp(*p, pwd->pw_name) == 0) {
 201                         dbmember = 1;
 202                         break;
 203                 }
 204 #endif
 205
 206         grp_passwd = grp->gr_passwd;
 207         if ((grp_passwd == NULL) || (grp_passwd[0] == '\0'))
 208                 grp_passwd = "*";
 209         if (!dbmember && getuid() != 0) {
 210                 pass = getpass("Password:");
 211                 if (pass == NULL ||
 212                     strcmp(grp_passwd, crypt(pass, grp_passwd)) != 0) {
 213                         fprintf(stderr, "Sorry\n");
 214                         return;
 215                 }
 216         }
 217
 218         ngrps_max = sysconf(_SC_NGROUPS_MAX) + 1;
 219         if ((grps = malloc(sizeof(gid_t) * ngrps_max)) == NULL)
 220                 err(1, "malloc");
 221         if ((ngrps = getgroups(ngrps_max, (gid_t *)grps)) < 0) {
 222                 warn("getgroups");
 223                 goto end;
 224         }
 225
 226         /* Remove requested gid from supp. list if it exists. */
 227         if (grp->gr_gid != egid && inarray(grp->gr_gid, grps, ngrps)) {
 228                 for (i = 0; i < ngrps; i++)
 229                         if (grps[i] == grp->gr_gid)
 230                                 break;
 231                 ngrps--;
 232                 memmove(&grps[i], &grps[i + 1], (ngrps - i) * sizeof(gid_t));
 233                 PRIV_START;
 234                 if (setgroups(ngrps, (const gid_t *)grps) < 0) {
 235                         PRIV_END;
 236                         warn("setgroups");
 237                         goto end;
 238                 }
 239                 PRIV_END;
 240         }
 241
 242         PRIV_START;
 243         if (setgid(grp->gr_gid)) {
 244                 PRIV_END;
 245                 warn("setgid");
 246                 goto end;
 247         }
 248         PRIV_END;
 249         grps[0] = grp->gr_gid;
 250
 251         /* Add old effective gid to supp. list if it does not exist. */
 252         if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) {
 253                 if (ngrps + 1 >= ngrps_max)
 254                         warnx("too many groups");
 255                 else {
 256                         grps[ngrps++] = egid;
 257                         PRIV_START;
 258                         if (setgroups(ngrps, (const gid_t *)grps)) {
 259                                 PRIV_END;
 260                                 warn("setgroups");
 261                                 goto end;
 262                         }
 263                         PRIV_END;
 264                 }
 265         }
 266
 267 end:
 268         free(grps);
 269 }
 270
 271 static int
 272 inarray(gid_t gid, const gid_t grps[], int ngrps)
 273 {
 274         int i;
 275
 276         for (i = 0; i < ngrps; i++)
 277                 if (grps[i] == gid)
 278                         return (1);
 279         return (0);
 280 }
 281
 282 /*
 283  * Set the environment to what would be expected if the user logged in
 284  * again; this performs the same steps as su(1)'s -l option.
 285  */
 286 static void
 287 loginshell(void)
 288 {
 289         char *args[2], **cleanenv, *term, *ticket;
 290         const char *shell;
 291         char *prog, progbuf[PATH_MAX];
 292 #ifndef __APPLE__
 293         login_cap_t *lc;
 294 #endif /* !__APPLE__ */
 295         shell = pwd->pw_shell;
 296         if (*shell == '\0')
 297                 shell = _PATH_BSHELL;
 298         if (chdir(pwd->pw_dir) < 0) {
 299                 warn("%s", pwd->pw_dir);
 300                 chdir("/");
 301         }
 302
 303         term = getenv("TERM");
 304         ticket = getenv("KRBTKFILE");
 305
 306         if ((cleanenv = calloc(20, sizeof(char *))) == NULL)
 307                 err(1, "calloc");
 308         *cleanenv = NULL;
 309         environ = cleanenv;
 310 #ifndef __APPLE__
 311         lc = login_getpwclass(pwd);
 312         setusercontext(lc, pwd, pwd->pw_uid,
 313             LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
 314         login_close(lc);
 315 #endif /* !__APPLE__ */
 316         setenv("USER", pwd->pw_name, 1);
 317         setenv("SHELL", shell, 1);
 318         setenv("HOME", pwd->pw_dir, 1);
 319         if (term != NULL)
 320                 setenv("TERM", term, 1);
 321         if (ticket != NULL)
 322                 setenv("KRBTKFILE", ticket, 1);
 323
 324         strlcpy(progbuf, shell, sizeof(progbuf));
 325         prog = basename(progbuf);
 326
 327         if (asprintf(args, "-%s", prog) < 0)
 328                 err(1, "asprintf");
 329         args[1] = NULL;
 330
 331         execv(shell, args);
 332         err(1, "%s", shell);
 333 }
 334
 335 static void
 336 doshell(void)
 337 {
 338         const char *shell;
 339         char *prog, progbuf[PATH_MAX];
 340
 341         shell = pwd->pw_shell;
 342         if (*shell == '\0')
 343                 shell = _PATH_BSHELL;
 344
 345         strlcpy(progbuf, shell, sizeof(progbuf));
 346         prog = basename(progbuf);
 347
 348         execl(shell, prog, (char *)NULL);
 349         err(1, "%s", shell);
 350 }