view kex.h @ 1930:299f4f19ba19

Add /usr/sbin and /sbin to default root PATH When dropbear is used in a very restricted environment (such as in a initrd), the default user shell is often also very restricted and doesn't take care of setting the PATH so the user ends up with the PATH set by dropbear. Unfortunately, dropbear always sets "/usr/bin:/bin" as default PATH even for the root user which should have /usr/sbin and /sbin too. For a concrete instance of this problem, see the "Remote Unlocking" section in this tutorial: https://paxswill.com/blog/2013/11/04/encrypted-raspberry-pi/ It speaks of a bug in the initramfs script because it's written "blkid" instead of "/sbin/blkid"... this is just because the scripts from the initramfs do not expect to have a PATH without the sbin directories and because dropbear is not setting the PATH appropriately for the root user. I'm thus suggesting to use the attached patch to fix this misbehaviour (I did not test it, but it's easy enough). It might seem anecdotic but multiple Kali users have been bitten by this. From https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
author Raphael Hertzog <hertzog@debian.org>
date Mon, 09 Jul 2018 16:27:53 +0200
parents 8f93f37c01de
children
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/*
 * 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_KEX_H_
#define DROPBEAR_KEX_H_

#include "includes.h"
#include "algo.h"
#include "signkey.h"

void send_msg_kexinit(void);
void recv_msg_kexinit(void);
void send_msg_newkeys(void);
void recv_msg_newkeys(void);
void kexfirstinitialise(void);
void finish_kexhashbuf(void);

#if DROPBEAR_NORMAL_DH
struct kex_dh_param *gen_kexdh_param(void);
void free_kexdh_param(struct kex_dh_param *param);
void kexdh_comb_key(struct kex_dh_param *param, mp_int *dh_pub_them,
		sign_key *hostkey);
#endif

#if DROPBEAR_ECDH
struct kex_ecdh_param *gen_kexecdh_param(void);
void free_kexecdh_param(struct kex_ecdh_param *param);
void kexecdh_comb_key(struct kex_ecdh_param *param, buffer *pub_them,
		sign_key *hostkey);
#endif

#if DROPBEAR_CURVE25519
struct kex_curve25519_param *gen_kexcurve25519_param(void);
void free_kexcurve25519_param(struct kex_curve25519_param *param);
void kexcurve25519_comb_key(const struct kex_curve25519_param *param, const buffer *pub_them,
		sign_key *hostkey);
#endif

#ifndef DISABLE_ZLIB
int is_compress_trans(void);
int is_compress_recv(void);
#endif

void recv_msg_kexdh_init(void); /* server */

void send_msg_kexdh_init(void); /* client */
void recv_msg_kexdh_reply(void); /* client */

void recv_msg_ext_info(void);

struct KEXState {

	unsigned sentkexinit : 1; /*set when we've sent/recv kexinit packet */
	unsigned recvkexinit : 1;
	unsigned them_firstfollows : 1; /* true when first_kex_packet_follows is set */
	unsigned sentnewkeys : 1; /* set once we've send MSG_NEWKEYS (will be cleared once we have also received */
	unsigned recvnewkeys : 1; /* set once we've received MSG_NEWKEYS (cleared once we have also sent */

	unsigned int donefirstkex; /* Set to 1 after the first kex has completed,
								  ie the transport layer has been set up */
	unsigned int donesecondkex; /* Set to 1 after the second kex has completed */

	unsigned our_first_follows_matches : 1;

	time_t lastkextime; /* time of the last kex */
	unsigned int datatrans; /* data transmitted since last kex */
	unsigned int datarecv; /* data received since last kex */

};

#if DROPBEAR_NORMAL_DH
struct kex_dh_param {
	mp_int pub; /* e */
	mp_int priv; /* x */
};
#endif

#if DROPBEAR_ECDH
struct kex_ecdh_param {
	ecc_key key;
};
#endif

#if DROPBEAR_CURVE25519
#define CURVE25519_LEN 32
struct kex_curve25519_param {
	unsigned char priv[CURVE25519_LEN];
	unsigned char pub[CURVE25519_LEN];
};
#endif

#endif /* DROPBEAR_KEX_H_ */