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a280b89982
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
/*
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* Module for modifying the secmark field of the skb, for use by
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* security subsystems.
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*
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* Based on the nfmark match by:
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* (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
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*
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* (C) 2006 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/selinux.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_SECMARK.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
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MODULE_DESCRIPTION("ip[6]tables SECMARK modification module");
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MODULE_ALIAS("ipt_SECMARK");
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MODULE_ALIAS("ip6t_SECMARK");
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#define PFX "SECMARK: "
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static u8 mode;
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static unsigned int target(struct sk_buff **pskb, const struct net_device *in,
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const struct net_device *out, unsigned int hooknum,
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const struct xt_target *target,
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const void *targinfo, void *userinfo)
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{
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u32 secmark = 0;
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const struct xt_secmark_target_info *info = targinfo;
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BUG_ON(info->mode != mode);
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switch (mode) {
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case SECMARK_MODE_SEL:
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secmark = info->u.sel.selsid;
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break;
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default:
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BUG();
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}
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if ((*pskb)->secmark != secmark)
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(*pskb)->secmark = secmark;
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return XT_CONTINUE;
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}
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static int checkentry_selinux(struct xt_secmark_target_info *info)
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{
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int err;
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struct xt_secmark_target_selinux_info *sel = &info->u.sel;
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sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
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err = selinux_string_to_sid(sel->selctx, &sel->selsid);
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if (err) {
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if (err == -EINVAL)
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printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n",
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sel->selctx);
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return 0;
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}
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if (!sel->selsid) {
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printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n",
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sel->selctx);
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return 0;
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}
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err = selinux_relabel_packet_permission(sel->selsid);
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if (err) {
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printk(KERN_INFO PFX "unable to obtain relabeling permission\n");
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return 0;
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}
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return 1;
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}
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static int checkentry(const char *tablename, const void *entry,
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const struct xt_target *target, void *targinfo,
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unsigned int targinfosize, unsigned int hook_mask)
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{
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struct xt_secmark_target_info *info = targinfo;
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if (mode && mode != info->mode) {
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printk(KERN_INFO PFX "mode already set to %hu cannot mix with "
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"rules for mode %hu\n", mode, info->mode);
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return 0;
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}
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switch (info->mode) {
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case SECMARK_MODE_SEL:
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if (!checkentry_selinux(info))
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return 0;
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break;
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default:
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printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
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return 0;
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}
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if (!mode)
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mode = info->mode;
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return 1;
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}
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static struct xt_target ipt_secmark_reg = {
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.name = "SECMARK",
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.target = target,
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.targetsize = sizeof(struct xt_secmark_target_info),
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.table = "mangle",
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.checkentry = checkentry,
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.me = THIS_MODULE,
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.family = AF_INET,
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.revision = 0,
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};
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static struct xt_target ip6t_secmark_reg = {
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.name = "SECMARK",
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.target = target,
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.targetsize = sizeof(struct xt_secmark_target_info),
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.table = "mangle",
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.checkentry = checkentry,
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.me = THIS_MODULE,
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.family = AF_INET6,
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.revision = 0,
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};
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static int __init xt_secmark_init(void)
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{
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int err;
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err = xt_register_target(&ipt_secmark_reg);
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if (err)
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return err;
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err = xt_register_target(&ip6t_secmark_reg);
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if (err)
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xt_unregister_target(&ipt_secmark_reg);
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return err;
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}
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static void __exit xt_secmark_fini(void)
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{
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xt_unregister_target(&ip6t_secmark_reg);
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xt_unregister_target(&ipt_secmark_reg);
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}
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module_init(xt_secmark_init);
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module_exit(xt_secmark_fini);
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