| 1 | /* |
| 2 | * chsh |
| 3 | */ |
| 4 | #include <stdio.h> |
| 5 | #include <signal.h> |
| 6 | #include <pwd.h> |
| 7 | |
| 8 | char passwd[] = "/etc/passwd"; |
| 9 | char temp[] = "/etc/ptmp"; |
| 10 | struct passwd *pwd; |
| 11 | struct passwd *getpwent(); |
| 12 | int endpwent(); |
| 13 | char *crypt(); |
| 14 | char *getpass(); |
| 15 | char *pw; |
| 16 | char pwbuf[10]; |
| 17 | char buf[BUFSIZ]; |
| 18 | |
| 19 | main(argc, argv) |
| 20 | char *argv[]; |
| 21 | { |
| 22 | char *p; |
| 23 | int i; |
| 24 | char saltc[2]; |
| 25 | long salt; |
| 26 | int u,fi,fo; |
| 27 | int insist; |
| 28 | int ok, flags; |
| 29 | int c; |
| 30 | int pwlen; |
| 31 | FILE *tf; |
| 32 | |
| 33 | insist = 0; |
| 34 | if(argc < 2 || argc > 3) { |
| 35 | printf("Usage: chsh user [ /bin/csh ]\n"); |
| 36 | goto bex; |
| 37 | } |
| 38 | if (argc == 2) |
| 39 | argv[2] = ""; |
| 40 | else if (strcmp(argv[2], "/bin/csh") && getuid()) { |
| 41 | printf("Only /bin/csh may be specified\n"); |
| 42 | exit(1); |
| 43 | } |
| 44 | while((pwd=getpwent()) != NULL){ |
| 45 | if(strcmp(pwd->pw_name,argv[1]) == 0){ |
| 46 | u = getuid(); |
| 47 | if(u!=0 && u != pwd->pw_uid){ |
| 48 | printf("Permission denied.\n"); |
| 49 | goto bex; |
| 50 | } |
| 51 | break; |
| 52 | } |
| 53 | } |
| 54 | endpwent(); |
| 55 | signal(SIGHUP, 1); |
| 56 | signal(SIGINT, 1); |
| 57 | signal(SIGQUIT, 1); |
| 58 | |
| 59 | if(access(temp, 0) >= 0) { |
| 60 | printf("Temporary file busy -- try again\n"); |
| 61 | goto bex; |
| 62 | } |
| 63 | if((tf=fopen(temp,"w")) == NULL) { |
| 64 | printf("Cannot create temporary file\n"); |
| 65 | goto bex; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * copy passwd to temp, replacing matching lines |
| 70 | * with new shell. |
| 71 | */ |
| 72 | |
| 73 | while((pwd=getpwent()) != NULL) { |
| 74 | if(strcmp(pwd->pw_name,argv[1]) == 0) { |
| 75 | u = getuid(); |
| 76 | if(u != 0 && u != pwd->pw_uid) { |
| 77 | printf("Permission denied.\n"); |
| 78 | goto out; |
| 79 | } |
| 80 | pwd->pw_shell = argv[2]; |
| 81 | } |
| 82 | fprintf(tf,"%s:%s:%d:%d:%s:%s:%s\n", |
| 83 | pwd->pw_name, |
| 84 | pwd->pw_passwd, |
| 85 | pwd->pw_uid, |
| 86 | pwd->pw_gid, |
| 87 | pwd->pw_gecos, |
| 88 | pwd->pw_dir, |
| 89 | pwd->pw_shell); |
| 90 | } |
| 91 | endpwent(); |
| 92 | fclose(tf); |
| 93 | |
| 94 | /* |
| 95 | * copy temp back to passwd file |
| 96 | */ |
| 97 | |
| 98 | if((fi=open(temp,0)) < 0) { |
| 99 | printf("Temp file disappeared!\n"); |
| 100 | goto out; |
| 101 | } |
| 102 | if((fo=creat(passwd, 0644)) < 0) { |
| 103 | printf("Cannot recreat passwd file.\n"); |
| 104 | goto out; |
| 105 | } |
| 106 | while((u=read(fi,buf,sizeof(buf))) > 0) write(fo,buf,u); |
| 107 | |
| 108 | out: |
| 109 | unlink(temp); |
| 110 | |
| 111 | bex: |
| 112 | exit(1); |
| 113 | } |