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/* setgrp.c - by Michael Haardt. Set the gid if possible */
/* Added a bit more error recovery/reporting - poe */
/* Vesa Roukonen added code for asking password */
/* Currently maintained at ftp://ftp.daimi.aau.dk/pub/linux/poe/ */
/* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*/
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include "c.h"
#include "pathnames.h"
#include "my_crypt.h"
#include "nls.h"
/* try to read password from gshadow */
static char *
get_gshadow_pwd(char *groupname)
{
char buf[BUFSIZ];
char *pwd = NULL;
FILE *f = fopen(_PATH_GSHADOW, "r");
if (groupname == NULL || *groupname == '\0' || f == NULL)
return NULL;
while(fgets(buf, sizeof buf, f))
{
char *cp = strchr (buf, ':');
if (!cp)
continue; /* any junk in gshadow? */
*cp = '\0';
if (strcmp(buf, groupname) == 0)
{
if (cp-buf >= BUFSIZ)
break; /* only group name on line */
pwd = cp+1;
if ((cp = strchr(pwd, ':')) && pwd == cp+1 )
pwd = NULL; /* empty password */
else if (cp)
*cp = '\0';
break;
}
}
fclose(f);
return pwd ? strdup(pwd) : NULL;
}
static int
allow_setgid(struct passwd *pe, struct group *ge)
{
char **look;
int notfound = 1;
char *pwd, *xpwd;
if (getuid() == 0) return TRUE; /* root may do anything */
if (ge->gr_gid == pe->pw_gid) return TRUE; /* You can switch back to your default group */
look = ge->gr_mem;
while (*look && (notfound = strcmp(*look++,pe->pw_name)));
if(!notfound) return TRUE; /* member of group => OK */
/* Ask for password. Often there is no password in /etc/group, so
contrary to login et al. we let an empty password mean the same
as * in /etc/passwd */
/* check /etc/gshadow */
if (!(pwd = get_gshadow_pwd(ge->gr_name)))
pwd = ge->gr_passwd;
if(pwd && *pwd && (xpwd = getpass(_("Password: ")))) {
if(strcmp(pwd, crypt(xpwd, pwd)) == 0)
return TRUE; /* password accepted */
}
return FALSE; /* default to denial */
}
int
main(int argc, char *argv[])
{
struct passwd *pw_entry;
struct group *gr_entry;
char *shell;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
if (!(pw_entry = getpwuid(getuid()))) {
perror(_("newgrp: Who are you?"));
exit(1);
}
shell = (pw_entry->pw_shell[0] ? pw_entry->pw_shell : _PATH_BSHELL);
if (argc < 2) {
if(setgid(pw_entry->pw_gid) < 0) {
perror(_("newgrp: setgid"));
exit(1);
}
} else {
errno = 0;
if (!(gr_entry = getgrnam(argv[1]))) {
if (errno)
perror(_("newgrp: No such group.")); /* error */
else
fprintf(stderr, "%s\n", _("newgrp: No such group.")); /* no group */
exit(1);
} else {
if(allow_setgid(pw_entry, gr_entry)) {
if(setgid(gr_entry->gr_gid) < 0) {
perror(_("newgrp: setgid"));
exit(1);
}
} else {
puts(_("newgrp: Permission denied"));
exit(1);
}
}
}
if(setuid(getuid()) < 0) {
perror(_("newgrp: setuid"));
exit(1);
}
fflush(stdout); fflush(stderr);
execl(shell,shell,(char*)0);
perror(_("No shell"));
fflush(stderr);
exit(1);
}
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