view listener.c @ 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 ce3ce75a6e04
children
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/*
 * Dropbear SSH
 * 
 * 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. */

#include "includes.h"
#include "listener.h"
#include "session.h"
#include "dbutil.h"

void listeners_initialise() {

	/* just one slot to start with */
	ses.listeners = (struct Listener**)m_malloc(sizeof(struct Listener*));
	ses.listensize = 1;
	ses.listeners[0] = NULL;

}

void set_listener_fds(fd_set * readfds) {

	unsigned int i, j;
	struct Listener *listener;

	/* check each in turn */
	for (i = 0; i < ses.listensize; i++) {
		listener = ses.listeners[i];
		if (listener != NULL) {
			for (j = 0; j < listener->nsocks; j++) {
				FD_SET(listener->socks[j], readfds);
			}
		}
	}
}


void handle_listeners(const fd_set * readfds) {

	unsigned int i, j;
	struct Listener *listener;
	int sock;

	/* check each in turn */
	for (i = 0; i < ses.listensize; i++) {
		listener = ses.listeners[i];
		if (listener != NULL) {
			for (j = 0; j < listener->nsocks; j++) {
				sock = listener->socks[j];
				if (FD_ISSET(sock, readfds)) {
					listener->acceptor(listener, sock);
				}
			}
		}
	}
} /* Woo brace matching */


/* acceptor(int fd, void* typedata) is a function to accept connections, 
 * cleanup(void* typedata) happens when cleaning up */
struct Listener* new_listener(const int socks[], unsigned int nsocks,
		int type, void* typedata, 
		void (*acceptor)(const struct Listener* listener, int sock),
		void (*cleanup)(const struct Listener*)) {

	unsigned int i, j;
	struct Listener *newlisten = NULL;
	/* try get a new structure to hold it */
	for (i = 0; i < ses.listensize; i++) {
		if (ses.listeners[i] == NULL) {
			break;
		}
	}

	/* or create a new one */
	if (i == ses.listensize) {
		if (ses.listensize > MAX_LISTENERS) {
			TRACE(("leave newlistener: too many already"))
			for (j = 0; j < nsocks; j++) {
				close(socks[i]);
			}
			return NULL;
		}
		
		ses.listeners = (struct Listener**)m_realloc(ses.listeners,
				(ses.listensize+LISTENER_EXTEND_SIZE)
				*sizeof(struct Listener*));

		ses.listensize += LISTENER_EXTEND_SIZE;

		for (j = i; j < ses.listensize; j++) {
			ses.listeners[j] = NULL;
		}
	}

	for (j = 0; j < nsocks; j++) {
		ses.maxfd = MAX(ses.maxfd, socks[j]);
	}

	TRACE(("new listener num %d ", i))

	newlisten = (struct Listener*)m_malloc(sizeof(struct Listener));
	newlisten->index = i;
	newlisten->type = type;
	newlisten->typedata = typedata;
	newlisten->nsocks = nsocks;
	memcpy(newlisten->socks, socks, nsocks * sizeof(int));
	newlisten->acceptor = acceptor;
	newlisten->cleanup = cleanup;

	ses.listeners[i] = newlisten;
	return newlisten;
}

/* Return the first listener which matches the type-specific comparison
 * function. Particularly needed for global requests, like tcp */
struct Listener * get_listener(int type, const void* typedata,
		int (*match)(const void*, const void*)) {

	unsigned int i;
	struct Listener* listener;

	for (i = 0, listener = ses.listeners[i]; i < ses.listensize; i++) {
		if (listener && listener->type == type
				&& match(typedata, listener->typedata)) {
			return listener;
		}
	}

	return NULL;
}

void remove_listener(struct Listener* listener) {

	unsigned int j;

	if (listener->cleanup) {
		listener->cleanup(listener);
	}

	for (j = 0; j < listener->nsocks; j++) {
		close(listener->socks[j]);
	}
	ses.listeners[listener->index] = NULL;
	m_free(listener);
}

void remove_all_listeners(void) {
	unsigned int i;
	for (i = 0; i < ses.listensize; i++) {
		if (ses.listeners[i]) {
			remove_listener(ses.listeners[i]);
		}
	}
	m_free(ses.listeners);
}