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/*-
* Copyright (c) 2003-2007, Petar Zhivkov Petrov <pesho.petrov@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <ctype.h>
#include <openssl/md5.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "auth.h"
#include "config.h"
#include "misc.h"
#include "proto.h"
#include "stream.h"
#define MD5_BYTES 16
/* This should be at least 2 * MD5_BYTES + 6 (length of "$md5$" + 1) */
#define MD5_CHARS_MAX (2*(MD5_BYTES)+6)
struct srvrecord {
char server[MAXHOSTNAMELEN];
char client[256];
char password[256];
};
static int auth_domd5auth(struct config *);
static int auth_lookuprecord(char *, struct srvrecord *);
static int auth_parsetoken(char **, char *, int);
static void auth_makesecret(struct srvrecord *, char *);
static void auth_makeresponse(char *, char *, char *);
static void auth_readablesum(unsigned char *, char *);
static void auth_makechallenge(struct config *, char *);
static int auth_checkresponse(char *, char *, char *);
int auth_login(struct config *config)
{
struct stream *s;
char hostbuf[MAXHOSTNAMELEN];
char *login, *host;
int error;
s = config->server;
error = gethostname(hostbuf, sizeof(hostbuf));
hostbuf[sizeof(hostbuf) - 1] = '\0';
if (error)
host = NULL;
else
host = hostbuf;
login = getlogin();
proto_printf(s, "USER %s %s\n", login != NULL ? login : "?",
host != NULL ? host : "?");
stream_flush(s);
error = auth_domd5auth(config);
return (error);
}
static int
auth_domd5auth(struct config *config)
{
struct stream *s;
char *line, *cmd, *challenge, *realm, *client, *srvresponse, *msg;
char shrdsecret[MD5_CHARS_MAX], response[MD5_CHARS_MAX];
char clichallenge[MD5_CHARS_MAX];
struct srvrecord auth;
int error;
lprintf(2, "MD5 authentication started\n");
s = config->server;
line = stream_getln(s, NULL);
cmd = proto_get_ascii(&line);
realm = proto_get_ascii(&line);
challenge = proto_get_ascii(&line);
if (challenge == NULL ||
line != NULL ||
(strcmp(cmd, "AUTHMD5") != 0)) {
lprintf(-1, "Invalid server reply to USER\n");
return (STATUS_FAILURE);
}
client = NULL;
response[0] = clichallenge[0] = '.';
response[1] = clichallenge[1] = 0;
if (config->reqauth || (strcmp(challenge, ".") != 0)) {
if (strcmp(realm, ".") == 0) {
lprintf(-1, "Authentication required, but not enabled on server\n");
return (STATUS_FAILURE);
}
error = auth_lookuprecord(realm, &auth);
if (error != STATUS_SUCCESS)
return (error);
client = auth.client;
auth_makesecret(&auth, shrdsecret);
}
if (strcmp(challenge, ".") != 0)
auth_makeresponse(challenge, shrdsecret, response);
if (config->reqauth)
auth_makechallenge(config, clichallenge);
proto_printf(s, "AUTHMD5 %s %s %s\n",
client == NULL ? "." : client, response, clichallenge);
stream_flush(s);
line = stream_getln(s, NULL);
cmd = proto_get_ascii(&line);
if (cmd == NULL || line == NULL)
goto bad;
if (strcmp(cmd, "OK") == 0) {
srvresponse = proto_get_ascii(&line);
if (srvresponse == NULL)
goto bad;
if (config->reqauth &&
!auth_checkresponse(srvresponse, clichallenge, shrdsecret)) {
lprintf(-1, "Server failed to authenticate itself to client\n");
return (STATUS_FAILURE);
}
lprintf(2, "MD5 authentication successful\n");
return (STATUS_SUCCESS);
}
if (strcmp(cmd, "!") == 0) {
msg = proto_get_rest(&line);
if (msg == NULL)
goto bad;
lprintf(-1, "Server error: %s\n", msg);
return (STATUS_FAILURE);
}
bad:
lprintf(-1, "Invalid server reply to AUTHMD5\n");
return (STATUS_FAILURE);
}
static int
auth_lookuprecord(char *server, struct srvrecord *auth)
{
char *home, *line, authfile[FILENAME_MAX];
struct stream *s;
int linenum = 0, error;
home = getenv("HOME");
if (home == NULL) {
lprintf(-1, "Environment variable \"HOME\" is not set\n");
return (STATUS_FAILURE);
}
snprintf(authfile, sizeof(authfile), "%s/%s", home, AUTHFILE);
s = stream_open_file(authfile, O_RDONLY);
if (s == NULL) {
lprintf(-1, "Could not open file %s\n", authfile);
return (STATUS_FAILURE);
}
while ((line = stream_getln(s, NULL)) != NULL) {
linenum++;
if (line[0] == '#' || line[0] == '\0')
continue;
error = auth_parsetoken(&line, auth->server,
sizeof(auth->server));
if (error != STATUS_SUCCESS) {
lprintf(-1, "%s:%d Missing client name\n", authfile, linenum);
goto close;
}
/* Skip the rest of this line, it isn't what we are looking for. */
if (strcasecmp(auth->server, server) != 0)
continue;
error = auth_parsetoken(&line, auth->client,
sizeof(auth->client));
if (error != STATUS_SUCCESS) {
lprintf(-1, "%s:%d Missing password\n", authfile, linenum);
goto close;
}
error = auth_parsetoken(&line, auth->password,
sizeof(auth->password));
if (error != STATUS_SUCCESS) {
lprintf(-1, "%s:%d Missing comment\n", authfile, linenum);
goto close;
}
stream_close(s);
lprintf(2, "Found authentication record for server \"%s\"\n",
server);
return (STATUS_SUCCESS);
}
lprintf(-1, "Unknown server \"%s\". Fix your %s\n", server , authfile);
memset(auth->password, 0, sizeof(auth->password));
close:
stream_close(s);
return (STATUS_FAILURE);
}
static int
auth_parsetoken(char **line, char *buf, int len)
{
char *colon;
colon = strchr(*line, ':');
if (colon == NULL)
return (STATUS_FAILURE);
*colon = 0;
buf[len - 1] = 0;
strncpy(buf, *line, len - 1);
*line = colon + 1;
return (STATUS_SUCCESS);
}
static void
auth_makesecret(struct srvrecord *auth, char *secret)
{
char *s, ch;
const char *md5salt = "$md5$";
unsigned char md5sum[MD5_BYTES];
MD5_CTX md5;
MD5_Init(&md5);
for (s = auth->client; *s != 0; ++s) {
ch = tolower(*s);
MD5_Update(&md5, &ch, 1);
}
MD5_Update(&md5, ":", 1);
for (s = auth->server; *s != 0; ++s) {
ch = tolower(*s);
MD5_Update(&md5, &ch, 1);
}
MD5_Update(&md5, ":", 1);
MD5_Update(&md5, auth->password, strlen(auth->password));
MD5_Final(md5sum, &md5);
memset(secret, 0, sizeof(secret));
strcpy(secret, md5salt);
auth_readablesum(md5sum, secret + strlen(md5salt));
}
static void
auth_makeresponse(char *challenge, char *sharedsecret, char *response)
{
MD5_CTX md5;
unsigned char md5sum[MD5_BYTES];
MD5_Init(&md5);
MD5_Update(&md5, sharedsecret, strlen(sharedsecret));
MD5_Update(&md5, ":", 1);
MD5_Update(&md5, challenge, strlen(challenge));
MD5_Final(md5sum, &md5);
auth_readablesum(md5sum, response);
}
/*
* Generates a challenge string which is an MD5 sum
* of a fairly random string. The purpose is to decrease
* the possibility of generating the same challenge
* string (even by different clients) more then once
* for the same server.
*/
static void
auth_makechallenge(struct config *config, char *challenge)
{
MD5_CTX md5;
unsigned char md5sum[MD5_BYTES];
char buf[128];
struct timeval tv;
struct sockaddr_in laddr;
pid_t pid, ppid;
int error, addrlen;
gettimeofday(&tv, NULL);
pid = getpid();
ppid = getppid();
srand(tv.tv_usec ^ tv.tv_sec ^ pid);
addrlen = sizeof(laddr);
error = getsockname(config->socket, (struct sockaddr *)&laddr, &addrlen);
if (error < 0) {
memset(&laddr, 0, sizeof(laddr));
}
gettimeofday(&tv, NULL);
MD5_Init(&md5);
snprintf(buf, sizeof(buf), "%s:%ld:%ld:%ld:%d:%d",
inet_ntoa(laddr.sin_addr), tv.tv_sec, tv.tv_usec, random(), pid, ppid);
MD5_Update(&md5, buf, strlen(buf));
MD5_Final(md5sum, &md5);
auth_readablesum(md5sum, challenge);
}
static int
auth_checkresponse(char *response, char *challenge, char *secret)
{
char correctresponse[MD5_CHARS_MAX];
auth_makeresponse(challenge, secret, correctresponse);
return (strcmp(response, correctresponse) == 0);
}
static void
auth_readablesum(unsigned char *md5sum, char *readable)
{
unsigned int i;
char *s = readable;
for (i = 0; i < MD5_BYTES; ++i, s+=2) {
sprintf(s, "%.2x", md5sum[i]);
}
}
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