The patch below fixes a problem in the iptables SECMARK target, where the user-supplied 'selctx' string may not be nul-terminated. From initial analysis, it seems that the strlen() called from selinux_string_to_sid() could run until it arbitrarily finds a zero, and possibly cause a kernel oops before then. The impact of this appears limited because the operation requires CAP_NET_ADMIN, which is essentially always root. Also, the module is not yet in wide use. Signed-off-by: James Morris <jmorris@namei.org> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: David S. Miller <davem@davemloft.net>
158 lines
3.5 KiB
C
158 lines
3.5 KiB
C
/*
|
|
* Module for modifying the secmark field of the skb, for use by
|
|
* security subsystems.
|
|
*
|
|
* Based on the nfmark match by:
|
|
* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
|
|
*
|
|
* (C) 2006 Red Hat, Inc., James Morris <jmorris@redhat.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/selinux.h>
|
|
#include <linux/netfilter/x_tables.h>
|
|
#include <linux/netfilter/xt_SECMARK.h>
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
|
|
MODULE_DESCRIPTION("ip[6]tables SECMARK modification module");
|
|
MODULE_ALIAS("ipt_SECMARK");
|
|
MODULE_ALIAS("ip6t_SECMARK");
|
|
|
|
#define PFX "SECMARK: "
|
|
|
|
static u8 mode;
|
|
|
|
static unsigned int target(struct sk_buff **pskb, const struct net_device *in,
|
|
const struct net_device *out, unsigned int hooknum,
|
|
const struct xt_target *target,
|
|
const void *targinfo, void *userinfo)
|
|
{
|
|
u32 secmark = 0;
|
|
const struct xt_secmark_target_info *info = targinfo;
|
|
|
|
BUG_ON(info->mode != mode);
|
|
|
|
switch (mode) {
|
|
case SECMARK_MODE_SEL:
|
|
secmark = info->u.sel.selsid;
|
|
break;
|
|
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
if ((*pskb)->secmark != secmark)
|
|
(*pskb)->secmark = secmark;
|
|
|
|
return XT_CONTINUE;
|
|
}
|
|
|
|
static int checkentry_selinux(struct xt_secmark_target_info *info)
|
|
{
|
|
int err;
|
|
struct xt_secmark_target_selinux_info *sel = &info->u.sel;
|
|
|
|
sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
|
|
|
|
err = selinux_string_to_sid(sel->selctx, &sel->selsid);
|
|
if (err) {
|
|
if (err == -EINVAL)
|
|
printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n",
|
|
sel->selctx);
|
|
return 0;
|
|
}
|
|
|
|
if (!sel->selsid) {
|
|
printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n",
|
|
sel->selctx);
|
|
return 0;
|
|
}
|
|
|
|
err = selinux_relabel_packet_permission(sel->selsid);
|
|
if (err) {
|
|
printk(KERN_INFO PFX "unable to obtain relabeling permission\n");
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int checkentry(const char *tablename, const void *entry,
|
|
const struct xt_target *target, void *targinfo,
|
|
unsigned int targinfosize, unsigned int hook_mask)
|
|
{
|
|
struct xt_secmark_target_info *info = targinfo;
|
|
|
|
if (mode && mode != info->mode) {
|
|
printk(KERN_INFO PFX "mode already set to %hu cannot mix with "
|
|
"rules for mode %hu\n", mode, info->mode);
|
|
return 0;
|
|
}
|
|
|
|
switch (info->mode) {
|
|
case SECMARK_MODE_SEL:
|
|
if (!checkentry_selinux(info))
|
|
return 0;
|
|
break;
|
|
|
|
default:
|
|
printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
|
|
return 0;
|
|
}
|
|
|
|
if (!mode)
|
|
mode = info->mode;
|
|
return 1;
|
|
}
|
|
|
|
static struct xt_target ipt_secmark_reg = {
|
|
.name = "SECMARK",
|
|
.target = target,
|
|
.targetsize = sizeof(struct xt_secmark_target_info),
|
|
.table = "mangle",
|
|
.checkentry = checkentry,
|
|
.me = THIS_MODULE,
|
|
.family = AF_INET,
|
|
.revision = 0,
|
|
};
|
|
|
|
static struct xt_target ip6t_secmark_reg = {
|
|
.name = "SECMARK",
|
|
.target = target,
|
|
.targetsize = sizeof(struct xt_secmark_target_info),
|
|
.table = "mangle",
|
|
.checkentry = checkentry,
|
|
.me = THIS_MODULE,
|
|
.family = AF_INET6,
|
|
.revision = 0,
|
|
};
|
|
|
|
static int __init xt_secmark_init(void)
|
|
{
|
|
int err;
|
|
|
|
err = xt_register_target(&ipt_secmark_reg);
|
|
if (err)
|
|
return err;
|
|
|
|
err = xt_register_target(&ip6t_secmark_reg);
|
|
if (err)
|
|
xt_unregister_target(&ipt_secmark_reg);
|
|
|
|
return err;
|
|
}
|
|
|
|
static void __exit xt_secmark_fini(void)
|
|
{
|
|
xt_unregister_target(&ip6t_secmark_reg);
|
|
xt_unregister_target(&ipt_secmark_reg);
|
|
}
|
|
|
|
module_init(xt_secmark_init);
|
|
module_exit(xt_secmark_fini);
|