74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
/* pwdauth 2.0 - check a shadow password Author: Kees J. Bot
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* 7 Feb 1994
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*
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* This program gets as input the key and salt arguments of the crypt(3)
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* function as two null terminated strings. The crypt result is output as
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* one null terminated string. Input and output must be <= 1024 characters.
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* The exit code will be 1 on any error.
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*
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* If the key has the form '##name' then the key will be encrypted and the
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* result checked to be equal to the encrypted password in the shadow password
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* file. If equal than '##name' will be returned, otherwise exit code 2.
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*
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* Otherwise the key will be encrypted normally and the result returned.
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*
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* As a special case, anything matches a null encrypted password to allow
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* a no-password login.
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*/
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#define nil 0
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#include <sys/types.h>
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#include <pwd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#define setkey pwdauth_setkey
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#define encrypt pwdauth_encrypt
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#define LEN 1024
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int main(int argc, char **argv)
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{
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char key[LEN];
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char *salt;
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struct passwd *pw;
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int n;
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/* Read input data. Check if there are exactly two null terminated
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* strings.
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*/
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n= read(0, key, LEN);
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if (n < 0) return 1;
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salt = key + n;
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n = 0;
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while (salt > key) if (*--salt == 0) n++;
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if (n != 2) return 1;
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salt = key + strlen(key) + 1;
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if (salt[0] == '#' && salt[1] == '#') {
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if ((pw= getpwnam(salt + 2)) == nil) return 2;
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/* A null encrypted password matches a null key, otherwise
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* do the normal crypt(3) authentication check.
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*/
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if (*pw->pw_passwd == 0 && *key == 0) {
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/* fine */
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} else
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if (strcmp(crypt(key, pw->pw_passwd), pw->pw_passwd) != 0) {
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return 2;
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}
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} else {
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/* Normal encryption. */
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if (*salt == 0 && *key == 0) {
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/* fine */
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} else {
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salt= crypt(key, salt);
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}
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}
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/* Return the (possibly new) salt to the caller. */
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if (write(1, salt, strlen(salt) + 1) < 0) return 1;
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return 0;
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}
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