| 1 | #include <stdio.h> |
| 2 | #include <grp.h> |
| 3 | #include <pwd.h> |
| 4 | |
| 5 | struct group *getgrnam(), *grp; |
| 6 | struct passwd *getpwuid(), *pwd; |
| 7 | char *getpass(), *crypt(); |
| 8 | |
| 9 | main(argc,argv) |
| 10 | int argc; |
| 11 | char **argv; |
| 12 | { |
| 13 | register i; |
| 14 | if(argc != 2) { |
| 15 | printf("usage: newgrp groupname\n"); |
| 16 | done(); |
| 17 | } |
| 18 | if((grp=getgrnam(argv[1])) == NULL) { |
| 19 | printf("%s: no such group\n", argv[1]); |
| 20 | done(); |
| 21 | } |
| 22 | if((pwd=getpwuid(getuid())) == NULL) { |
| 23 | printf("You do not exist!\n"); |
| 24 | done(); |
| 25 | } |
| 26 | for(i=0;grp->gr_mem[i];i++) |
| 27 | if(strcmp(grp->gr_mem[i], pwd->pw_name) == 0) |
| 28 | break; |
| 29 | if(grp->gr_mem[i] == 0 && strcmp(grp->gr_name,"other")) { |
| 30 | printf("Sorry\n"); |
| 31 | done(); |
| 32 | } |
| 33 | |
| 34 | if(grp->gr_passwd[0] != '\0' && pwd->pw_passwd[0] == '\0') { |
| 35 | if(strcmp(grp->gr_passwd, crypt(getpass("Password:"),grp->gr_passwd)) != 0) { |
| 36 | printf("Sorry\n"); |
| 37 | done(); |
| 38 | } |
| 39 | } |
| 40 | if(setgid(grp->gr_gid) < 0) |
| 41 | perror("setgid"); |
| 42 | done(); |
| 43 | } |
| 44 | |
| 45 | done() |
| 46 | { |
| 47 | register i; |
| 48 | |
| 49 | setuid(getuid()); |
| 50 | for (i=3; i<15; i++) |
| 51 | close(i); |
| 52 | execl("/bin/sh", "sh", 0); |
| 53 | printf("No shell!\n"); |
| 54 | exit(0); |
| 55 | } |