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/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* 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.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
#include <sys/wait.h>
#include <arpa/inet.h>
#include <net/auth.h>
#include <net/listen.h>
#include <net/param.h>
#include <net/stpsession.h>
#include <crypto/ecdh.h>
#include <otconfig.h>
#include <stdio.h>
#include <unistd.h>
#define KEY_BYTE_WIDTH 32
static void
log_pubkey(uint8_t pubkey[KEY_BYTE_WIDTH])
{
for (size_t i = 0; i < KEY_BYTE_WIDTH; ++i) {
printf("%02X ", pubkey[i] & 0xFF);
if (i != 0 && i % 4 == 0) {
printf("\n");
}
}
printf("\n");
}
static void
send_motd(int client_fd, const unsigned char *session_key)
{
char motd[] = MOTD;
printf("Sending MOTD...\n");
if (send_frame(client_fd, motd, sizeof(motd), session_key) < 0) {
printf("Failed to session MOTD\n");
}
}
/*
* Check a password to see if it matches with
* the hash in /etc/shadow by using the pwcheck
* script. Returns 0 on success.
*/
static int
pwcheck(char *username, char *pw)
{
char *pwcheck = "/usr/local/bin/pwcheck";
pid_t pid;
char *args[] = {pwcheck, username, pw, NULL};
int status;
pid = fork();
if (pid == 0) {
execv(pwcheck, args);
}
if (waitpid(pid, &status, 0) < 0) {
printf("waidpid() failed\n");
return -1;
}
if (WIFEXITED(status)) {
return WEXITSTATUS(status);
}
return -1;
}
static int
passwd_auth(int client_fd, const unsigned char *session_key)
{
int error;
struct session_auth auth;
const size_t LEN = sizeof(auth);
if (!REQUIRE_USER_AUTH) {
return 0;
}
error = recv_frame(client_fd, sizeof(auth), session_key, &auth);
if (error < 0) {
return error;
}
if (pwcheck(auth.username, auth.password) != 0) {
printf("Got bad password for %s\n", auth.username);
auth.code = AUTH_BAD_PW;
error = send_frame(client_fd, &auth, sizeof(auth), session_key);
if (error < 0) {
printf("Failed to ACK user authentication with frame\n");
}
return -1;
}
auth.code = AUTH_SUCCESS;
error = send_frame(client_fd, &auth, sizeof(auth), session_key);
if (error < 0) {
printf("Failed to ACK user authentication with frame\n");
return error;
}
return 0;
}
static int
client_echo(int client_fd, const unsigned char *session_key)
{
char buf[4096];
int error;
error = recv_frame(client_fd, sizeof(buf) - 1, session_key, buf);
if (error < 0) {
return error;
}
/* Echo frame to all clients */
for (size_t i = 1; i < MAX_CLIENTS; ++i) {
if (clients[i] <= 0)
continue;
send_frame(clients[i], buf, sizeof(buf), session_key);
}
return 0;
}
/*
* Verify the session request packet and handle
* the rest.
*
* @client_fd: File descriptor for client socket.
* @srq: Session request packet.
*/
int
handle_srq(int client_fd, struct session_request *srq)
{
struct x25519_keypair keypair;
unsigned char *session_key;
int error;
if (REQUIRE_USER_AUTH && !ISSET(srq->options, SESSION_REQ_USER)) {
printf("%x\n", srq->options);
printf("User authentication enforced but client 'U' bit not set\n");
printf("Closing connection...\n");
return -1;
}
printf("Got public key from peer: \n");
log_pubkey(srq->pubkey);
printf("Generating keys...\n");
if (gen_x25519_keypair(&keypair) < 0) {
printf("Key generation failed!\n");
return -1;
}
/* Send back our our public key */
error = send(client_fd, keypair.pubkey, keypair.pubkey_len, 0);
if (error < 0) {
perror("Failed to send public key");
return error;
}
printf("Deriving session key...\n");
error = gen_session_key(keypair.privkey, srq->pubkey, &session_key);
if (error < 0) {
return error;
}
/* Handle any requested session parameters */
if ((error = negotiate_spw(client_fd, session_key)) < 0) {
free_session_key(session_key);
return error;
}
send_motd(client_fd, session_key);
free_session_key(session_key);
return 0;
}
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