367 lines
7.3 KiB
C
367 lines
7.3 KiB
C
/* $NetBSD: skeylogin.c,v 1.6 1996/09/19 19:39:48 thorpej Exp $ */
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/* S/KEY v1.1b (skeylogin.c)
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*
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* Authors:
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* Neil M. Haller <nmh@thumper.bellcore.com>
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* Philip R. Karn <karn@chicago.qualcomm.com>
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* John S. Walden <jsw@thumper.bellcore.com>
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* Scott Chasin <chasin@crimelab.com>
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*
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* S/KEY verification check, lookups, and authentication.
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*/
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#include <sys/param.h>
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#ifdef QUOTA
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#include <sys/quota.h>
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#endif
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/timeb.h>
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#include <sys/resource.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <time.h>
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#include <errno.h>
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#include "skey.h"
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#define _PATH_KEYFILE "/etc/skeykeys"
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char *skipspace __ARGS((char *));
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int skeylookup __ARGS((struct skey *, char *));
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/* Issue a skey challenge for user 'name'. If successful,
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* fill in the caller's skey structure and return 0. If unsuccessful
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* (e.g., if name is unknown) return -1.
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*
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* The file read/write pointer is left at the start of the
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* record.
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*/
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int
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getskeyprompt(mp,name,prompt)
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struct skey *mp;
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char *name;
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char *prompt;
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{
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int rval;
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sevenbit(name);
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rval = skeylookup(mp,name);
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strcpy(prompt,"s/key 55 latour1\n");
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switch (rval) {
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case -1: /* File error */
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return -1;
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case 0: /* Lookup succeeded, return challenge */
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sprintf(prompt,"s/key %d %s\n",mp->n - 1,mp->seed);
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return 0;
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case 1: /* User not found */
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fclose(mp->keyfile);
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return -1;
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}
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return -1; /* Can't happen */
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}
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/* Return a skey challenge string for user 'name'. If successful,
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* fill in the caller's skey structure and return 0. If unsuccessful
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* (e.g., if name is unknown) return -1.
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*
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* The file read/write pointer is left at the start of the
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* record.
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*/
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int
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skeychallenge(mp,name, ss)
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struct skey *mp;
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char *name;
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char *ss;
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{
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int rval;
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rval = skeylookup(mp,name);
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switch(rval){
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case -1: /* File error */
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return -1;
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case 0: /* Lookup succeeded, issue challenge */
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sprintf(ss, "s/key %d %s",mp->n - 1,mp->seed);
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return 0;
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case 1: /* User not found */
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fclose(mp->keyfile);
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return -1;
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}
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return -1; /* Can't happen */
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}
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/* Find an entry in the One-time Password database.
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* Return codes:
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* -1: error in opening database
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* 0: entry found, file R/W pointer positioned at beginning of record
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* 1: entry not found, file R/W pointer positioned at EOF
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*/
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int
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skeylookup(mp,name)
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struct skey *mp;
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char *name;
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{
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int found;
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int len;
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long recstart;
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char *cp;
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struct stat statbuf;
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/* See if the _PATH_KEYFILE exists, and create it if not */
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if (stat(_PATH_KEYFILE,&statbuf) == -1 && errno == ENOENT) {
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mp->keyfile = fopen(_PATH_KEYFILE,"w+");
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if (mp->keyfile)
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chmod(_PATH_KEYFILE, 0644);
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} else {
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/* Otherwise open normally for update */
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mp->keyfile = fopen(_PATH_KEYFILE,"r+");
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}
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if (mp->keyfile == NULL)
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return -1;
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/* Look up user name in database */
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len = strlen(name);
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if( len > 8 ) len = 8; /* Added 8/2/91 - nmh */
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found = 0;
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while (!feof(mp->keyfile)) {
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recstart = ftell(mp->keyfile);
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mp->recstart = recstart;
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if (fgets(mp->buf,sizeof(mp->buf),mp->keyfile) != mp->buf) {
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break;
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}
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rip(mp->buf);
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if (mp->buf[0] == '#')
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continue; /* Comment */
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if ((mp->logname = strtok(mp->buf," \t")) == NULL)
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continue;
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if ((cp = strtok(NULL," \t")) == NULL)
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continue;
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mp->n = atoi(cp);
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if ((mp->seed = strtok(NULL," \t")) == NULL)
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continue;
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if ((mp->val = strtok(NULL," \t")) == NULL)
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continue;
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if (strlen(mp->logname) == len
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&& strncmp(mp->logname,name,len) == 0){
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found = 1;
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break;
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}
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}
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if (found) {
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fseek(mp->keyfile,recstart,0);
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return 0;
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} else
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return 1;
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}
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/* Verify response to a s/key challenge.
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*
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* Return codes:
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* -1: Error of some sort; database unchanged
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* 0: Verify successful, database updated
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* 1: Verify failed, database unchanged
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*
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* The database file is always closed by this call.
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*/
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int
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skeyverify(mp,response)
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struct skey *mp;
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char *response;
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{
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char key[8];
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char fkey[8];
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char filekey[8];
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time_t now;
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struct tm *tm;
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char tbuf[27];
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char *cp;
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time(&now);
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tm = localtime(&now);
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strftime(tbuf, sizeof(tbuf), " %b %d,%Y %T", tm);
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if (response == NULL) {
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fclose(mp->keyfile);
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return -1;
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}
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rip(response);
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/* Convert response to binary */
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if (etob(key, response) != 1 && atob8(key, response) != 0) {
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/* Neither english words or ascii hex */
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fclose(mp->keyfile);
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return -1;
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}
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/* Compute fkey = f(key) */
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memcpy(fkey,key,sizeof(key));
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fflush (stdout);
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f(fkey);
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/*
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* in order to make the window of update as short as possible
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* we must do the comparison here and if OK write it back
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* other wise the same password can be used twice to get in
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* to the system
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*/
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setpriority(PRIO_PROCESS, 0, -4);
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/* reread the file record NOW*/
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fseek(mp->keyfile,mp->recstart,0);
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if (fgets(mp->buf,sizeof(mp->buf),mp->keyfile) != mp->buf){
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setpriority(PRIO_PROCESS, 0, 0);
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fclose(mp->keyfile);
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return -1;
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}
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rip(mp->buf);
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mp->logname = strtok(mp->buf," \t");
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cp = strtok(NULL," \t") ;
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mp->seed = strtok(NULL," \t");
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mp->val = strtok(NULL," \t");
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/* And convert file value to hex for comparison */
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atob8(filekey,mp->val);
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/* Do actual comparison */
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fflush (stdout);
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if (memcmp(filekey,fkey,8) != 0){
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/* Wrong response */
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setpriority(PRIO_PROCESS, 0, 0);
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fclose(mp->keyfile);
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return 1;
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}
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/*
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* Update key in database by overwriting entire record. Note
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* that we must write exactly the same number of bytes as in
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* the original record (note fixed width field for N)
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*/
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btoa8(mp->val,key);
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mp->n--;
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fseek(mp->keyfile,mp->recstart,0);
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fprintf(mp->keyfile, "%s %04d %-16s %s %-21s\n",
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mp->logname,mp->n,mp->seed, mp->val, tbuf);
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fclose(mp->keyfile);
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setpriority(PRIO_PROCESS, 0, 0);
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return 0;
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}
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/*
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* skey_haskey ()
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*
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* Returns: 1 user doesnt exist, -1 fle error, 0 user exists.
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*
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*/
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int
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skey_haskey (username)
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char *username;
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{
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int i;
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struct skey skey;
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return (skeylookup (&skey, username));
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}
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/*
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* skey_keyinfo ()
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*
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* Returns the current sequence number and
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* seed for the passed user.
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*
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*/
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char *
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skey_keyinfo (username)
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char *username;
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{
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int i;
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static char str [50];
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struct skey skey;
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i = skeychallenge (&skey, username, str);
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if (i == -1)
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return 0;
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return str;
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}
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/*
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* skey_passcheck ()
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*
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* Check to see if answer is the correct one to the current
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* challenge.
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*
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* Returns: 0 success, -1 failure
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*
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*/
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int
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skey_passcheck (username, passwd)
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char *username, *passwd;
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{
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int i;
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struct skey skey;
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i = skeylookup (&skey, username);
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if (i == -1 || i == 1)
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return -1;
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if (skeyverify (&skey, passwd) == 0)
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return skey.n;
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return -1;
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}
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/*
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* skey_authenticate ()
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*
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* Used when calling program will allow input of the user's
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* response to the challenge.
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*
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* Returns: 0 success, -1 failure
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*
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*/
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int
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skey_authenticate (username)
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char *username;
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{
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int i;
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char pbuf[256], skeyprompt[50];
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struct skey skey;
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/* Attempt a S/Key challenge */
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i = skeychallenge (&skey, username, skeyprompt);
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if (i == -2)
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return 0;
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printf("[%s]\n", skeyprompt);
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fflush(stdout);
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printf("Response: ");
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readskey(pbuf, sizeof (pbuf));
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rip(pbuf);
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/* Is it a valid response? */
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if (i == 0 && skeyverify (&skey, pbuf) == 0) {
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if (skey.n < 5) {
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printf ("\nWarning! Key initialization needed soon. ");
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printf ("(%d logins left)\n", skey.n);
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}
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return 0;
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}
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return -1;
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}
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