diff options
Diffstat (limited to 'usr.bin/newgrp/newgrp.c')
| -rw-r--r-- | usr.bin/newgrp/newgrp.c | 309 |
1 files changed, 309 insertions, 0 deletions
diff --git a/usr.bin/newgrp/newgrp.c b/usr.bin/newgrp/newgrp.c new file mode 100644 index 000000000000..f1da1c8cb1f5 --- /dev/null +++ b/usr.bin/newgrp/newgrp.c @@ -0,0 +1,309 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2002 Tim J. Robbins. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * newgrp -- change to a new group + */ + +#include <sys/types.h> + +#include <err.h> +#include <errno.h> +#include <grp.h> +#include <limits.h> +#include <login_cap.h> +#include <paths.h> +#include <pwd.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +static void addgroup(const char *grpname); +static void doshell(void); +static int inarray(gid_t, const gid_t[], int); +static void loginshell(void); +static void restoregrps(void); +static void usage(void); + +static struct passwd *pwd; +static uid_t euid; + +extern char **environ; + +/* Manipulate effective user ID. */ +#define PRIV_START do { \ + if (seteuid(euid) < 0) \ + err(1, "seteuid"); \ + } while (0) +#define PRIV_END do { \ + if (seteuid(getuid()) < 0) \ + err(1, "seteuid"); \ + } while (0) + +int +main(int argc, char *argv[]) +{ + int ch, login; + + if ((euid = geteuid()) != 0) + warnx("need root permissions to function properly, check setuid bit"); + if (seteuid(getuid()) < 0) + err(1, "seteuid"); + + if ((pwd = getpwuid(getuid())) == NULL) + errx(1, "unknown user"); + + login = 0; + while ((ch = getopt(argc, argv, "-l")) != -1) { + switch (ch) { + case '-': /* Obsolescent */ + case 'l': + login = 1; + break; + default: + usage(); + } + } + argc -= optind; + argv += optind; + + switch (argc) { + case 0: + restoregrps(); + break; + case 1: + addgroup(*argv); + break; + default: + usage(); + } + + if (seteuid(euid) < 0) + err(1, "seteuid"); + if (setuid(getuid()) < 0) + err(1, "setuid"); + + if (login) + loginshell(); + else + doshell(); + + /*NOTREACHED*/ + exit(1); +} + +static void +usage(void) +{ + + fprintf(stderr, "usage: newgrp [-l] [group]\n"); + exit(1); +} + +static void +restoregrps(void) +{ + int initres, setres; + + PRIV_START; + initres = initgroups(pwd->pw_name, pwd->pw_gid); + setres = setgid(pwd->pw_gid); + PRIV_END; + + if (initres < 0) + warn("initgroups"); + if (setres < 0) + warn("setgid"); +} + +static void +addgroup(const char *grpname) +{ + gid_t *grps; + long lgid, ngrps_max; + int dbmember, i, ngrps; + gid_t egid; + struct group *grp; + char *ep, *pass, *cryptpw; + char **p; + + egid = getegid(); + + /* Try it as a group name, then a group id. */ + if ((grp = getgrnam(grpname)) == NULL) + if ((lgid = strtol(grpname, &ep, 10)) <= 0 || *ep != '\0' || + (grp = getgrgid((gid_t)lgid)) == NULL ) { + warnx("%s: bad group name", grpname); + return; + } + + /* + * If the user is not a member of the requested group and the group + * has a password, prompt and check it. + */ + dbmember = 0; + if (pwd->pw_gid == grp->gr_gid) + dbmember = 1; + for (p = grp->gr_mem; *p != NULL; p++) + if (strcmp(*p, pwd->pw_name) == 0) { + dbmember = 1; + break; + } + if (!dbmember && *grp->gr_passwd != '\0' && getuid() != 0) { + pass = getpass("Password:"); + if (pass == NULL) + return; + cryptpw = crypt(pass, grp->gr_passwd); + if (cryptpw == NULL || strcmp(grp->gr_passwd, cryptpw) != 0) { + fprintf(stderr, "Sorry\n"); + return; + } + } + + ngrps_max = sysconf(_SC_NGROUPS_MAX) + 1; + if ((grps = malloc(sizeof(gid_t) * ngrps_max)) == NULL) + err(1, "malloc"); + if ((ngrps = getgroups(ngrps_max, (gid_t *)grps)) < 0) { + warn("getgroups"); + goto end; + } + + /* Remove requested gid from supp. list if it exists. */ + if (grp->gr_gid != egid && inarray(grp->gr_gid, grps, ngrps)) { + for (i = 0; i < ngrps; i++) + if (grps[i] == grp->gr_gid) + break; + ngrps--; + memmove(&grps[i], &grps[i + 1], (ngrps - i) * sizeof(gid_t)); + PRIV_START; + if (setgroups(ngrps, (const gid_t *)grps) < 0) { + PRIV_END; + warn("setgroups"); + goto end; + } + PRIV_END; + } + + PRIV_START; + if (setgid(grp->gr_gid)) { + PRIV_END; + warn("setgid"); + goto end; + } + PRIV_END; + grps[0] = grp->gr_gid; + + /* Add old effective gid to supp. list if it does not exist. */ + if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) { + if (ngrps == ngrps_max) + warnx("too many groups"); + else { + grps[ngrps++] = egid; + PRIV_START; + if (setgroups(ngrps, (const gid_t *)grps)) { + PRIV_END; + warn("setgroups"); + goto end; + } + PRIV_END; + } + } +end: + free(grps); +} + +static int +inarray(gid_t gid, const gid_t grps[], int ngrps) +{ + int i; + + for (i = 0; i < ngrps; i++) + if (grps[i] == gid) + return (1); + return (0); +} + +/* + * Set the environment to what would be expected if the user logged in + * again; this performs the same steps as su(1)'s -l option. + */ +static void +loginshell(void) +{ + char *args[2], **cleanenv, *term, *ticket; + const char *shell; + login_cap_t *lc; + + shell = pwd->pw_shell; + if (*shell == '\0') + shell = _PATH_BSHELL; + if (chdir(pwd->pw_dir) < 0) { + warn("%s", pwd->pw_dir); + chdir("/"); + } + + term = getenv("TERM"); + ticket = getenv("KRBTKFILE"); + + if ((cleanenv = calloc(20, sizeof(char *))) == NULL) + err(1, "calloc"); + *cleanenv = NULL; + environ = cleanenv; + + lc = login_getpwclass(pwd); + setusercontext(lc, pwd, pwd->pw_uid, + LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV); + login_close(lc); + setenv("USER", pwd->pw_name, 1); + setenv("SHELL", shell, 1); + setenv("HOME", pwd->pw_dir, 1); + if (term != NULL) + setenv("TERM", term, 1); + if (ticket != NULL) + setenv("KRBTKFILE", ticket, 1); + + if (asprintf(args, "-%s", shell) < 0) + err(1, "asprintf"); + args[1] = NULL; + + execv(shell, args); + err(1, "%s", shell); +} + +static void +doshell(void) +{ + const char *shell; + + shell = pwd->pw_shell; + if (*shell == '\0') + shell = _PATH_BSHELL; + execl(shell, shell, (char *)NULL); + err(1, "%s", shell); +} |