view dbutil.h @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents e11ed628708b
children 90ac15aeac43
line wrap: on
line source

/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#ifndef DROPBEAR_DBUTIL_H_

#define DROPBEAR_DBUTIL_H_

#include "includes.h"
#include "buffer.h"
#include "queue.h"
#include "dbhelpers.h"
#include "dbmalloc.h"

#ifndef DISABLE_SYSLOG
void startsyslog(const char *ident);
#endif

extern void (*_dropbear_exit)(int exitcode, const char* format, va_list param) ATTRIB_NORETURN;
extern void (*_dropbear_log)(int priority, const char* format, va_list param);

void dropbear_exit(const char* format, ...) ATTRIB_PRINTF(1,2) ATTRIB_NORETURN;

void dropbear_close(const char* format, ...) ATTRIB_PRINTF(1,2) ;
void dropbear_log(int priority, const char* format, ...) ATTRIB_PRINTF(2,3) ;

void fail_assert(const char* expr, const char* file, int line) ATTRIB_NORETURN;

#if DEBUG_TRACE
void dropbear_trace(const char* format, ...) ATTRIB_PRINTF(1,2);
void dropbear_trace2(const char* format, ...) ATTRIB_PRINTF(1,2);
void printhex(const char * label, const unsigned char * buf, int len);
void printmpint(const char *label, mp_int *mp);
void debug_start_net(void);
extern int debug_trace;
#endif

char * stripcontrol(const char * text);

int spawn_command(void(*exec_fn)(const void *user_data), const void *exec_data,
		int *writefd, int *readfd, int *errfd, pid_t *pid);
void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell);
#if ENABLE_CONNECT_UNIX
int connect_unix(const char* addr);
#endif
int buf_readfile(buffer* buf, const char* filename);
int buf_getline(buffer * line, FILE * authfile);

void m_close(int fd);
void setnonblocking(int fd);
void disallow_core(void);
int m_str_to_uint(const char* str, unsigned int *val);

/* Used to force mp_ints to be initialised */
#define DEF_MP_INT(X) mp_int X = {0, 0, 0, NULL}

/* Dropbear assertion */
#define dropbear_assert(X) do { if (!(X)) { fail_assert(#X, __FILE__, __LINE__); } } while (0)

/* Returns 0 if a and b have the same contents */
int constant_time_memcmp(const void* a, const void *b, size_t n);

/* Returns a time in seconds that doesn't go backwards - does not correspond to
a real-world clock */
time_t monotonic_now(void);
/* Higher resolution clock_gettime(CLOCK_MONOTONIC) wrapper */
void gettime_wrapper(struct timespec *now);

char * expand_homedir_path(const char *inpath);

void fsync_parent_dir(const char* fn);

#if DROPBEAR_MSAN
/* FD_ZERO seems to leave some memory uninitialized. clear it to avoid false positives */
#define DROPBEAR_FD_ZERO(fds) do { memset((fds), 0x0, sizeof(fd_set)); FD_ZERO(fds); } while(0)
#else
#define DROPBEAR_FD_ZERO(fds) FD_ZERO(fds)
#endif

#endif /* DROPBEAR_DBUTIL_H_ */