passwords.c

linux内核

/* -*- c -*- ------------------------------------------------------------- *
 *   
 *   Copyright 2004-2005 Murali Krishnan Ganapathy - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Bostom MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

#include "passwords.h"
#include "des.h"
#include "string.h"
#include <stdlib.h>
#include <stdio.h>
#include "tui.h"

#define MAX_LINE 512 
// Max line length in a pwdfile
p_pwdentry userdb[MAX_USERS]; // Array of pointers
int numusers; // Actual number of users

// returns true or false, i.e. 1 or 0
char authenticate_user(const char * username, const char* pwd)
{
  char salt[12];
  int  i, password_ok;

  password_ok=0;

  for (i=0; i< numusers; i++) {
    if (userdb[i] == NULL) continue;
    if (strcmp(username,userdb[i]->username)==0) {
      strcpy(salt, userdb[i]->pwdhash);
      salt[2] = '\0';
      if (strcmp(userdb[i]->pwdhash,crypt(pwd,salt))==0) return 1;
    }
  }
  return 0;
}

// Does user USERNAME  have permission PERM
char isallowed(const char *username, const char *perm)
{
  int i;
  char *dperm;
  char *tmp;

  if (strcmp(username,GUEST_USER) == 0) return 0;
  dperm = (char *) malloc(strlen(perm)+3);
  strcpy(dperm+1,perm);
  dperm[0] = ':';
  dperm[strlen(perm)+1]=':';
  dperm[strlen(perm)+2]=0;
  // Now dperm = ":perm:"
  for (i=0; i < numusers; i++) {
     if (strcmp(userdb[i]->username,username)==0) // Found the user
     {
        if (userdb[i]->perms == NULL) return 0; // No permission
        tmp = strstr(userdb[i]->perms,dperm); // Search for permission
        free (dperm); // Release memory
        if (tmp == NULL) return 0; else return 1;
     }
  }
  // User not found return 0
  free (dperm);
  return 0;
}

// Initialise the list of of user passwords permissions from file
void init_passwords(const char *filename)
{
  int i;
  char line[MAX_LINE], *p,*user,*pwdhash,*perms;
  FILE *f;

  for (i=0; i < MAX_USERS; i++) userdb[i] = NULL;
  numusers = 0;
 
  if ( !filename ) return; // No filename specified

  f = fopen(filename,"r");
  if ( !f ) return; // File does not exist

  // Process each line
  while ( fgets(line, sizeof line, f) ) {
    // Replace EOLN with \0
    p = strchr(line, '\r');
    if ( p ) *p = '\0';
    p = strchr(line, '\n');
    if ( p ) *p = '\0';

    // If comment line or empty ignore line
    p = line;
    while (*p==' ') p++; // skip initial spaces
    if ( (*p == '#') || (*p == '\0')) continue; // Skip comment lines

    user = p; // This is where username starts
    p = strchr(user,':');
    if (p == NULL) continue; // Malformed line skip
    *p = '\0';
    pwdhash = p+1;
    if (*pwdhash == 0) continue; // Malformed line (no password specified)
    p = strchr(pwdhash,':'); 
    if (p == NULL) { // No perms specified
       perms = NULL;
    } else {
       *p = '\0';
       perms = p+1;
       if (*perms == 0) perms = NULL;
    }
    // At this point we have user,pwdhash and perms setup 
    userdb[numusers] = (p_pwdentry)malloc(sizeof(pwdentry));
    strcpy(userdb[numusers]->username,user);
    strcpy(userdb[numusers]->pwdhash,pwdhash);
    if (perms == NULL)
      userdb[numusers]->perms = NULL;
    else {
      userdb[numusers]->perms = (char *)malloc(strlen(perms)+3);
      (userdb[numusers]->perms)[0] = ':';
      strcpy(userdb[numusers]->perms + 1,perms);
      (userdb[numusers]->perms)[strlen(perms)+1] = ':';
      (userdb[numusers]->perms)[strlen(perms)+2] = 0;
      // Now perms field points to ":perms:"
    }
    numusers++;
  }
  fclose(f);
}

void close_passwords()
{
  int i;

  for (i=0; i < numusers; i++)
    if (userdb[i] != NULL) free(userdb[i]);
  numusers = 0;
}