#include <stdio.h> #include <grp.h> #include <pwd.h> struct group *getgrnam(), *grp; struct passwd *getpwuid(), *pwd; char *getpass(), *crypt(); main(argc,argv) int argc; char **argv; { register i; if(argc != 2) { printf("usage: newgrp groupname\n"); exit(13); } if((grp=getgrnam(argv[1])) == NULL) { printf("%s: no such group\n", argv[1]); exit(13); } if((pwd=getpwuid(getuid())) == NULL) { printf("You do not exist!\n"); exit(13); } for(i=0;grp->gr_mem[i];i++) if(strcmp(grp->gr_mem[i], pwd->pw_name) == 0) break; if(grp->gr_mem[i] == 0 && strcmp(grp->gr_name,"other")) { printf("Sorry\n"); exit(13); } if(grp->gr_passwd[0] != '\0' && pwd->pw_passwd[0] == '\0') { if(strcmp(grp->gr_passwd, crypt(getpass("Password:"),grp->gr_passwd)) != 0) { printf("Sorry\n"); exit(13); } } if(setgid(grp->gr_gid) < 0) { perror("setgid"); exit(13); } setuid(getuid()); for (i=3; i<15; i++) close(i); execl((pwd->pw_shell[0]?pwd->pw_shell:"/bin/sh"), "-i", 0); printf("No shell!\n"); exit(0); }