| 1 | /* |
| 2 | * enter a password in the password file |
| 3 | * this program should be suid with owner |
| 4 | * with an owner with write permission on /etc/passwd |
| 5 | */ |
| 6 | #include <stdio.h> |
| 7 | #include <signal.h> |
| 8 | #include <pwd.h> |
| 9 | |
| 10 | char passwd[] = "/etc/passwd"; |
| 11 | char temp[] = "/etc/ptmp"; |
| 12 | struct passwd *pwd; |
| 13 | struct passwd *getpwent(); |
| 14 | int endpwent(); |
| 15 | char *strcpy(); |
| 16 | char *crypt(); |
| 17 | char *getpass(); |
| 18 | char *getlogin(); |
| 19 | char *pw; |
| 20 | char pwbuf[10]; |
| 21 | char buf[512]; |
| 22 | |
| 23 | main(argc, argv) |
| 24 | char *argv[]; |
| 25 | { |
| 26 | char *p; |
| 27 | int i; |
| 28 | char saltc[2]; |
| 29 | long salt; |
| 30 | int u,fi,fo; |
| 31 | int insist; |
| 32 | int ok, flags; |
| 33 | int c; |
| 34 | int pwlen; |
| 35 | FILE *tf; |
| 36 | char *uname; |
| 37 | |
| 38 | insist = 0; |
| 39 | if(argc < 2) { |
| 40 | if ((uname = getlogin()) == NULL) { |
| 41 | printf ("Usage: passwd user\n"); |
| 42 | goto bex; |
| 43 | } else { |
| 44 | printf("Changing password for %s\n", uname); |
| 45 | } |
| 46 | } else { |
| 47 | uname = argv[1]; |
| 48 | } |
| 49 | while(((pwd=getpwent()) != NULL)&&(strcmp(pwd->pw_name,uname)!=0)); |
| 50 | u = getuid(); |
| 51 | if((pwd==NULL) || (u!=0 && u != pwd->pw_uid)) |
| 52 | { |
| 53 | printf("Permission denied.\n"); |
| 54 | goto bex; |
| 55 | } |
| 56 | endpwent(); |
| 57 | if (pwd->pw_passwd[0] && u != 0) { |
| 58 | strcpy(pwbuf, getpass("Old password:")); |
| 59 | pw = crypt(pwbuf, pwd->pw_passwd); |
| 60 | if(strcmp(pw, pwd->pw_passwd) != 0) { |
| 61 | printf("Sorry.\n"); |
| 62 | goto bex; |
| 63 | } |
| 64 | } |
| 65 | tryagn: |
| 66 | strcpy(pwbuf, getpass("New password:")); |
| 67 | pwlen = strlen(pwbuf); |
| 68 | if (pwlen == 0) { |
| 69 | printf("Password unchanged.\n"); |
| 70 | goto bex; |
| 71 | } |
| 72 | ok = 0; |
| 73 | flags = 0; |
| 74 | p = pwbuf; |
| 75 | while(c = *p++){ |
| 76 | if(c>='a' && c<='z') flags |= 2; |
| 77 | else if(c>='A' && c<='Z') flags |= 4; |
| 78 | else if(c>='0' && c<='9') flags |= 1; |
| 79 | else flags |= 8; |
| 80 | } |
| 81 | if(flags >=7 && pwlen>= 4) ok = 1; |
| 82 | if(((flags==2)||(flags==4)) && pwlen>=6) ok = 1; |
| 83 | if(((flags==3)||(flags==5)||(flags==6))&&pwlen>=5) ok = 1; |
| 84 | |
| 85 | if((ok==0) && (insist<2)){ |
| 86 | if(flags==1) |
| 87 | printf("Please use at least one non-numeric character.\n"); |
| 88 | else |
| 89 | printf("Please use a longer password.\n"); |
| 90 | insist++; |
| 91 | goto tryagn; |
| 92 | } |
| 93 | |
| 94 | if (strcmp(pwbuf,getpass("Retype new password:")) != 0) { |
| 95 | printf ("Mismatch - password unchanged.\n"); |
| 96 | goto bex; |
| 97 | } |
| 98 | |
| 99 | time(&salt); |
| 100 | salt += getpid(); |
| 101 | |
| 102 | saltc[0] = salt & 077; |
| 103 | saltc[1] = (salt>>6) & 077; |
| 104 | for(i=0;i<2;i++){ |
| 105 | c = saltc[i] + '.'; |
| 106 | if(c>'9') c += 7; |
| 107 | if(c>'Z') c += 6; |
| 108 | saltc[i] = c; |
| 109 | } |
| 110 | pw = crypt(pwbuf, saltc); |
| 111 | signal(SIGHUP, SIG_IGN); |
| 112 | signal(SIGINT, SIG_IGN); |
| 113 | signal(SIGQUIT, SIG_IGN); |
| 114 | |
| 115 | if(access(temp, 0) >= 0) { |
| 116 | printf("Temporary file busy -- try again\n"); |
| 117 | goto bex; |
| 118 | } |
| 119 | close(creat(temp,0600)); |
| 120 | if((tf=fopen(temp,"w")) == NULL) { |
| 121 | printf("Cannot create temporary file\n"); |
| 122 | goto bex; |
| 123 | } |
| 124 | |
| 125 | /* |
| 126 | * copy passwd to temp, replacing matching lines |
| 127 | * with new password. |
| 128 | */ |
| 129 | |
| 130 | while((pwd=getpwent()) != NULL) { |
| 131 | if(strcmp(pwd->pw_name,uname) == 0) { |
| 132 | u = getuid(); |
| 133 | if(u != 0 && u != pwd->pw_uid) { |
| 134 | printf("Permission denied.\n"); |
| 135 | goto out; |
| 136 | } |
| 137 | pwd->pw_passwd = pw; |
| 138 | } |
| 139 | fprintf(tf,"%s:%s:%d:%d:%s:%s:%s\n", |
| 140 | pwd->pw_name, |
| 141 | pwd->pw_passwd, |
| 142 | pwd->pw_uid, |
| 143 | pwd->pw_gid, |
| 144 | pwd->pw_gecos, |
| 145 | pwd->pw_dir, |
| 146 | pwd->pw_shell); |
| 147 | } |
| 148 | endpwent(); |
| 149 | fclose(tf); |
| 150 | |
| 151 | /* |
| 152 | * copy temp back to passwd file |
| 153 | */ |
| 154 | |
| 155 | if((fi=open(temp,0)) < 0) { |
| 156 | printf("Temp file disappeared!\n"); |
| 157 | goto out; |
| 158 | } |
| 159 | if((fo=creat(passwd, 0644)) < 0) { |
| 160 | printf("Cannot recreat passwd file.\n"); |
| 161 | goto out; |
| 162 | } |
| 163 | while((u=read(fi,buf,sizeof(buf))) > 0) write(fo,buf,u); |
| 164 | |
| 165 | out: |
| 166 | unlink(temp); |
| 167 | |
| 168 | bex: |
| 169 | exit(1); |
| 170 | } |