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/*
* Copyright (c) 2025 Ian Marco Moffett and L5 engineers
* 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 the project 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/iotap.h>
#include <sys/spawn.h>
#include <sys/wait.h>
#include <stddef.h>
#include <ctype.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include "blake2.h"
#define DEFAULT_SHELL "/usr/bin/hush"
/* Max lengths */
#define USERNAME_MAX 128
#define PASSWORD_MAX 256
/*
* Read input from an input device
*
* @buf: Buffer to fill with input
* @maxlen: Max length of buffer
* @bool: True if characters should be plaintext
*/
static void
read_input(char *buf, size_t maxlen, bool show)
{
ssize_t retval;
size_t i = 0;
char c = '\0';
char vis_c;
struct iotap_msg msg = {
.opcode = IOTAP_OPC_READ,
.buf = &c,
.len = 1
};
if (buf == NULL) {
return;
}
/* Zero for security */
memset(buf, 0, maxlen);
/*
* Read all the input until we hit a '\n'
*/
do {
retval = iotap_mux("input.igkbd", &msg);
if (retval < 0) {
continue;
}
if (!isascii(c)) {
continue;
}
/* Don't overwrite prompt */
if (c == '\b' && i == 0) {
continue;
}
/* Is this a backspace? */
if (c == '\b' && i > 0) {
buf[--i] = '\0';
write(STDOUT_FILENO, &c, 1);
continue;
}
if (c != '\n' && i < maxlen) {
vis_c = (show) ? c : '*';
buf[i++] = c;
write(STDOUT_FILENO, &vis_c, 1);
}
} while (c != '\n');
printf("\n");
}
static int
auth(const char *username, char *hash)
{
char passwd_path[128];
char real_hash[BLAKE2B_OUTBYTES];
int fd, retval = 0;
/* Get the real password hash */
snprintf(
passwd_path,
sizeof(passwd_path),
"/ucred/%s/passwd",
username
);
fd = open(passwd_path, O_RDONLY);
if (fd < 0) {
return fd;
}
read(fd, real_hash, BLAKE2B_OUTBYTES);
if (memcmp(hash, real_hash, BLAKE2B_OUTBYTES) != 0) {
retval = -EPERM;
}
close(fd);
return retval;
}
int
main(void)
{
char shell_path[] = DEFAULT_SHELL;
char *argv_dmmy[] = { DEFAULT_SHELL, NULL };
char login[USERNAME_MAX];
char password[PASSWORD_MAX];
char hash[BLAKE2B_OUTBYTES];
pid_t shell_pid;
int error;
printf("- the points have aligned -\n");
printf("** authenticate yourself **\n");
for (;;) {
/* Get the username */
printf("login: ");
read_input(login, sizeof(login), true);
/* Get the password */
printf("password: ");
read_input(password, sizeof(password), false);
/*
* We need to hash this right away and keep the plaintext
* password in memory as little as possible
*/
blake2b(
hash,
BLAKE2B_OUTBYTES,
password,
strlen(password),
NULL,
0
);
memset(password, 0, sizeof(password));
error = auth(login, hash);
if (error < 0) {
printf("error: bad login\n");
continue;
}
break;
}
shell_pid = spawn(shell_path, argv_dmmy);
waitpid(shell_pid, NULL, 0);
return 0;
}
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