From d071ef10b29607561994ddaab80321545c09c142 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Wed, 15 Oct 2025 15:03:07 -0400 Subject: cmd: Add initial 'login' program This commit introduces the initial login program to require a user to enter their credentials before they can use the system Signed-off-by: Ian Moffett --- src/cmd/login/login.c | 189 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 189 insertions(+) create mode 100644 src/cmd/login/login.c (limited to 'src/cmd/login/login.c') diff --git a/src/cmd/login/login.c b/src/cmd/login/login.c new file mode 100644 index 0000000..3e77ac4 --- /dev/null +++ b/src/cmd/login/login.c @@ -0,0 +1,189 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#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; +} -- cgit v1.2.3