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c567853089
libvirt/src/util/iptables.c
Daniel P. Berrange c567853089 CVE-2010-2242 Apply a source port mapping to virtual network masquerading 
IPtables will seek to preserve the source port unchanged when
doing masquerading, if possible. NFS has a pseudo-security
option where it checks for the source port <= 1023 before
allowing a mount request. If an admin has used this to make the
host OS trusted for mounts, the default iptables behaviour will
potentially allow NAT'd guests access too. This needs to be
stopped.

With this change, the iptables -t nat -L -n -v rules for the
default network will be

Chain POSTROUTING (policy ACCEPT 95 packets, 9163 bytes)
 pkts bytes target     prot opt in     out     source               destination
   14   840 MASQUERADE  tcp  --  *      *       192.168.122.0/24    !192.168.122.0/24    masq ports: 1024-65535
   75  5752 MASQUERADE  udp  --  *      *       192.168.122.0/24    !192.168.122.0/24    masq ports: 1024-65535
    0     0 MASQUERADE  all  --  *      *       192.168.122.0/24    !192.168.122.0/24

* src/network/bridge_driver.c: Add masquerade rules for TCP
  and UDP protocols
* src/util/iptables.c, src/util/iptables.c: Add source port
  mappings for TCP & UDP protocols when masquerading.
2010-07-19 15:50:27 +01:00

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/*
* Copyright (C) 2007-2010 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Authors:
* Mark McLoughlin <markmc@redhat.com>
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include "internal.h"
#include "iptables.h"
#include "util.h"
#include "memory.h"
#include "virterror_internal.h"
#include "logging.h"
enum {
ADD = 0,
REMOVE
};
typedef struct
{
char *table;
char *chain;
} iptRules;
struct _iptablesContext
{
iptRules *input_filter;
iptRules *forward_filter;
iptRules *nat_postrouting;
};
static void
iptRulesFree(iptRules *rules)
{
VIR_FREE(rules->table);
VIR_FREE(rules->chain);
VIR_FREE(rules);
}
static iptRules *
iptRulesNew(const char *table,
const char *chain)
{
iptRules *rules;
if (VIR_ALLOC(rules) < 0)
return NULL;
if (!(rules->table = strdup(table)))
goto error;
if (!(rules->chain = strdup(chain)))
goto error;
return rules;
error:
iptRulesFree(rules);
return NULL;
}
static int ATTRIBUTE_SENTINEL
iptablesAddRemoveRule(iptRules *rules, int action, const char *arg, ...)
{
va_list args;
int retval = ENOMEM;
const char **argv;
const char *s;
int n;
n = 1 + /* /sbin/iptables */
2 + /* --table foo */
2 + /* --insert bar */
1; /* arg */
va_start(args, arg);
while (va_arg(args, const char *))
n++;
va_end(args);
if (VIR_ALLOC_N(argv, n + 1) < 0)
goto error;
n = 0;
if (!(argv[n++] = strdup(IPTABLES_PATH)))
goto error;
if (!(argv[n++] = strdup("--table")))
goto error;
if (!(argv[n++] = strdup(rules->table)))
goto error;
if (!(argv[n++] = strdup(action == ADD ? "--insert" : "--delete")))
goto error;
if (!(argv[n++] = strdup(rules->chain)))
goto error;
if (!(argv[n++] = strdup(arg)))
goto error;
va_start(args, arg);
while ((s = va_arg(args, const char *))) {
if (!(argv[n++] = strdup(s))) {
va_end(args);
goto error;
}
}
va_end(args);
if (virRun(argv, NULL) < 0) {
retval = errno;
goto error;
}
retval = 0;
error:
if (argv) {
n = 0;
while (argv[n])
VIR_FREE(argv[n++]);
VIR_FREE(argv);
}
return retval;
}
/**
* iptablesContextNew:
*
* Create a new IPtable context
*
* Returns a pointer to the new structure or NULL in case of error
*/
iptablesContext *
iptablesContextNew(void)
{
iptablesContext *ctx;
if (VIR_ALLOC(ctx) < 0)
return NULL;
if (!(ctx->input_filter = iptRulesNew("filter", "INPUT")))
goto error;
if (!(ctx->forward_filter = iptRulesNew("filter", "FORWARD")))
goto error;
if (!(ctx->nat_postrouting = iptRulesNew("nat", "POSTROUTING")))
goto error;
return ctx;
error:
iptablesContextFree(ctx);
return NULL;
}
/**
* iptablesContextFree:
* @ctx: pointer to the IP table context
*
* Free the resources associated with an IP table context
*/
void
iptablesContextFree(iptablesContext *ctx)
{
if (ctx->input_filter)
iptRulesFree(ctx->input_filter);
if (ctx->forward_filter)
iptRulesFree(ctx->forward_filter);
if (ctx->nat_postrouting)
iptRulesFree(ctx->nat_postrouting);
VIR_FREE(ctx);
}
static int
iptablesInput(iptablesContext *ctx,
const char *iface,
int port,
int action,
int tcp)
{
char portstr[32];
snprintf(portstr, sizeof(portstr), "%d", port);
portstr[sizeof(portstr) - 1] = '\0';
return iptablesAddRemoveRule(ctx->input_filter,
action,
"--in-interface", iface,
"--protocol", tcp ? "tcp" : "udp",
"--destination-port", portstr,
"--jump", "ACCEPT",
NULL);
}
/**
* iptablesAddTcpInput:
* @ctx: pointer to the IP table context
* @iface: the interface name
* @port: the TCP port to add
*
* Add an input to the IP table allowing access to the given @port on
* the given @iface interface for TCP packets
*
* Returns 0 in case of success or an error code in case of error
*/
int
iptablesAddTcpInput(iptablesContext *ctx,
const char *iface,
int port)
{
return iptablesInput(ctx, iface, port, ADD, 1);
}
/**
* iptablesRemoveTcpInput:
* @ctx: pointer to the IP table context
* @iface: the interface name
* @port: the TCP port to remove
*
* Removes an input from the IP table, hence forbidding access to the given
* @port on the given @iface interface for TCP packets
*
* Returns 0 in case of success or an error code in case of error
*/
int
iptablesRemoveTcpInput(iptablesContext *ctx,
const char *iface,
int port)
{
return iptablesInput(ctx, iface, port, REMOVE, 1);
}
/**
* iptablesAddUdpInput:
* @ctx: pointer to the IP table context
* @iface: the interface name
* @port: the UDP port to add
*
* Add an input to the IP table allowing access to the given @port on
* the given @iface interface for UDP packets
*
* Returns 0 in case of success or an error code in case of error
*/
int
iptablesAddUdpInput(iptablesContext *ctx,
const char *iface,
int port)
{
return iptablesInput(ctx, iface, port, ADD, 0);
}
/**
* iptablesRemoveUdpInput:
* @ctx: pointer to the IP table context
* @iface: the interface name
* @port: the UDP port to remove
*
* Removes an input from the IP table, hence forbidding access to the given
* @port on the given @iface interface for UDP packets
*
* Returns 0 in case of success or an error code in case of error
*/
int
iptablesRemoveUdpInput(iptablesContext *ctx,
const char *iface,
int port)
{
return iptablesInput(ctx, iface, port, REMOVE, 0);
}
/* Allow all traffic coming from the bridge, with a valid network address
* to proceed to WAN
*/
static int
iptablesForwardAllowOut(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev,
int action)
{
if (physdev && physdev[0]) {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--source", network,
"--in-interface", iface,
"--out-interface", physdev,
"--jump", "ACCEPT",
NULL);
} else {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--source", network,
"--in-interface", iface,
"--jump", "ACCEPT",
NULL);
}
}
/**
* iptablesAddForwardAllowOut:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the source interface name
* @physdev: the physical output device
*
* Add a rule to the IP table context to allow the traffic for the
* network @network via interface @iface to be forwarded to
* @physdev device. This allow the outbound traffic on a bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardAllowOut(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowOut(ctx, network, iface, physdev, ADD);
}
/**
* iptablesRemoveForwardAllowOut:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the source interface name
* @physdev: the physical output device
*
* Remove a rule from the IP table context hence forbidding forwarding
* of the traffic for the network @network via interface @iface
* to the @physdev device output. This stops the outbound traffic on a bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardAllowOut(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowOut(ctx, network, iface, physdev, REMOVE);
}
/* Allow all traffic destined to the bridge, with a valid network address
* and associated with an existing connection
*/
static int
iptablesForwardAllowRelatedIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev,
int action)
{
if (physdev && physdev[0]) {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--destination", network,
"--in-interface", physdev,
"--out-interface", iface,
"--match", "state",
"--state", "ESTABLISHED,RELATED",
"--jump", "ACCEPT",
NULL);
} else {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--destination", network,
"--out-interface", iface,
"--match", "state",
"--state", "ESTABLISHED,RELATED",
"--jump", "ACCEPT",
NULL);
}
}
/**
* iptablesAddForwardAllowRelatedIn:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the output interface name
* @physdev: the physical input device or NULL
*
* Add rules to the IP table context to allow the traffic for the
* network @network on @physdev device to be forwarded to
* interface @iface, if it is part of an existing connection.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardAllowRelatedIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowRelatedIn(ctx, network, iface, physdev, ADD);
}
/**
* iptablesRemoveForwardAllowRelatedIn:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the output interface name
* @physdev: the physical input device or NULL
*
* Remove rules from the IP table context hence forbidding the traffic for
* network @network on @physdev device to be forwarded to
* interface @iface, if it is part of an existing connection.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardAllowRelatedIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowRelatedIn(ctx, network, iface, physdev, REMOVE);
}
/* Allow all traffic destined to the bridge, with a valid network address
*/
static int
iptablesForwardAllowIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev,
int action)
{
if (physdev && physdev[0]) {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--destination", network,
"--in-interface", physdev,
"--out-interface", iface,
"--jump", "ACCEPT",
NULL);
} else {
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--destination", network,
"--out-interface", iface,
"--jump", "ACCEPT",
NULL);
}
}
/**
* iptablesAddForwardAllowIn:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the output interface name
* @physdev: the physical input device or NULL
*
* Add rules to the IP table context to allow the traffic for the
* network @network on @physdev device to be forwarded to
* interface @iface. This allow the inbound traffic on a bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardAllowIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowIn(ctx, network, iface, physdev, ADD);
}
/**
* iptablesRemoveForwardAllowIn:
* @ctx: pointer to the IP table context
* @network: the source network name
* @iface: the output interface name
* @physdev: the physical input device or NULL
*
* Remove rules from the IP table context hence forbidding the traffic for
* network @network on @physdev device to be forwarded to
* interface @iface. This stops the inbound traffic on a bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardAllowIn(iptablesContext *ctx,
const char *network,
const char *iface,
const char *physdev)
{
return iptablesForwardAllowIn(ctx, network, iface, physdev, REMOVE);
}
/* Allow all traffic between guests on the same bridge,
* with a valid network address
*/
static int
iptablesForwardAllowCross(iptablesContext *ctx,
const char *iface,
int action)
{
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--in-interface", iface,
"--out-interface", iface,
"--jump", "ACCEPT",
NULL);
}
/**
* iptablesAddForwardAllowCross:
* @ctx: pointer to the IP table context
* @iface: the input/output interface name
*
* Add rules to the IP table context to allow traffic to cross that
* interface. It allows all traffic between guests on the same bridge
* represented by that interface.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardAllowCross(iptablesContext *ctx,
const char *iface) {
return iptablesForwardAllowCross(ctx, iface, ADD);
}
/**
* iptablesRemoveForwardAllowCross:
* @ctx: pointer to the IP table context
* @iface: the input/output interface name
*
* Remove rules to the IP table context to block traffic to cross that
* interface. It forbids traffic between guests on the same bridge
* represented by that interface.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardAllowCross(iptablesContext *ctx,
const char *iface) {
return iptablesForwardAllowCross(ctx, iface, REMOVE);
}
/* Drop all traffic trying to forward from the bridge.
* ie the bridge is the in interface
*/
static int
iptablesForwardRejectOut(iptablesContext *ctx,
const char *iface,
int action)
{
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--in-interface", iface,
"--jump", "REJECT",
NULL);
}
/**
* iptablesAddForwardRejectOut:
* @ctx: pointer to the IP table context
* @iface: the output interface name
*
* Add rules to the IP table context to forbid all traffic to that
* interface. It forbids forwarding from the bridge to that interface.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardRejectOut(iptablesContext *ctx,
const char *iface)
{
return iptablesForwardRejectOut(ctx, iface, ADD);
}
/**
* iptablesRemoveForwardRejectOut:
* @ctx: pointer to the IP table context
* @iface: the output interface name
*
* Remove rules from the IP table context forbidding all traffic to that
* interface. It reallow forwarding from the bridge to that interface.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardRejectOut(iptablesContext *ctx,
const char *iface)
{
return iptablesForwardRejectOut(ctx, iface, REMOVE);
}
/* Drop all traffic trying to forward to the bridge.
* ie the bridge is the out interface
*/
static int
iptablesForwardRejectIn(iptablesContext *ctx,
const char *iface,
int action)
{
return iptablesAddRemoveRule(ctx->forward_filter,
action,
"--out-interface", iface,
"--jump", "REJECT",
NULL);
}
/**
* iptablesAddForwardRejectIn:
* @ctx: pointer to the IP table context
* @iface: the input interface name
*
* Add rules to the IP table context to forbid all traffic from that
* interface. It forbids forwarding from that interface to the bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardRejectIn(iptablesContext *ctx,
const char *iface)
{
return iptablesForwardRejectIn(ctx, iface, ADD);
}
/**
* iptablesRemoveForwardRejectIn:
* @ctx: pointer to the IP table context
* @iface: the input interface name
*
* Remove rules from the IP table context forbidding all traffic from that
* interface. It allows forwarding from that interface to the bridge.
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardRejectIn(iptablesContext *ctx,
const char *iface)
{
return iptablesForwardRejectIn(ctx, iface, REMOVE);
}
/* Masquerade all traffic coming from the network associated
* with the bridge
*/
static int
iptablesForwardMasquerade(iptablesContext *ctx,
const char *network,
const char *physdev,
const char *protocol,
int action)
{
if (protocol && protocol[0]) {
if (physdev && physdev[0]) {
return iptablesAddRemoveRule(ctx->nat_postrouting,
action,
"--source", network,
"-p", protocol,
"!", "--destination", network,
"--out-interface", physdev,
"--jump", "MASQUERADE",
"--to-ports", "1024-65535",
NULL);
} else {
return iptablesAddRemoveRule(ctx->nat_postrouting,
action,
"--source", network,
"-p", protocol,
"!", "--destination", network,
"--jump", "MASQUERADE",
"--to-ports", "1024-65535",
NULL);
}
} else {
if (physdev && physdev[0]) {
return iptablesAddRemoveRule(ctx->nat_postrouting,
action,
"--source", network,
"!", "--destination", network,
"--out-interface", physdev,
"--jump", "MASQUERADE",
NULL);
} else {
return iptablesAddRemoveRule(ctx->nat_postrouting,
action,
"--source", network,
"!", "--destination", network,
"--jump", "MASQUERADE",
NULL);
}
}
}
/**
* iptablesAddForwardMasquerade:
* @ctx: pointer to the IP table context
* @network: the source network name
* @physdev: the physical input device or NULL
* @protocol: the network protocol or NULL
*
* Add rules to the IP table context to allow masquerading
* network @network on @physdev. This allow the bridge to
* masquerade for that network (on @physdev).
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesAddForwardMasquerade(iptablesContext *ctx,
const char *network,
const char *physdev,
const char *protocol)
{
return iptablesForwardMasquerade(ctx, network, physdev, protocol, ADD);
}
/**
* iptablesRemoveForwardMasquerade:
* @ctx: pointer to the IP table context
* @network: the source network name
* @physdev: the physical input device or NULL
* @protocol: the network protocol or NULL
*
* Remove rules from the IP table context to stop masquerading
* network @network on @physdev. This stops the bridge from
* masquerading for that network (on @physdev).
*
* Returns 0 in case of success or an error code otherwise
*/
int
iptablesRemoveForwardMasquerade(iptablesContext *ctx,
const char *network,
const char *physdev,
const char *protocol)
{
return iptablesForwardMasquerade(ctx, network, physdev, protocol, REMOVE);
}
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