// SPDX-License-Identifier: GPL-2.0-only
|
/*
|
* Kernel module to match various things tied to sockets associated with
|
* locally generated outgoing packets.
|
*
|
* (C) 2000 Marc Boucher <marc@mbsi.ca>
|
*
|
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
|
*/
|
#include <linux/module.h>
|
#include <linux/skbuff.h>
|
#include <linux/file.h>
|
#include <linux/cred.h>
|
|
#include <net/sock.h>
|
#include <net/inet_sock.h>
|
#include <linux/netfilter/x_tables.h>
|
#include <linux/netfilter/xt_owner.h>
|
|
static int owner_check(const struct xt_mtchk_param *par)
|
{
|
struct xt_owner_match_info *info = par->matchinfo;
|
struct net *net = par->net;
|
|
if (info->match & ~XT_OWNER_MASK)
|
return -EINVAL;
|
|
/* Only allow the common case where the userns of the writer
|
* matches the userns of the network namespace.
|
*/
|
if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) &&
|
(current_user_ns() != net->user_ns))
|
return -EINVAL;
|
|
/* Ensure the uids are valid */
|
if (info->match & XT_OWNER_UID) {
|
kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);
|
kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);
|
|
if (!uid_valid(uid_min) || !uid_valid(uid_max) ||
|
(info->uid_max < info->uid_min) ||
|
uid_lt(uid_max, uid_min)) {
|
return -EINVAL;
|
}
|
}
|
|
/* Ensure the gids are valid */
|
if (info->match & XT_OWNER_GID) {
|
kgid_t gid_min = make_kgid(net->user_ns, info->gid_min);
|
kgid_t gid_max = make_kgid(net->user_ns, info->gid_max);
|
|
if (!gid_valid(gid_min) || !gid_valid(gid_max) ||
|
(info->gid_max < info->gid_min) ||
|
gid_lt(gid_max, gid_min)) {
|
return -EINVAL;
|
}
|
}
|
|
return 0;
|
}
|
|
static bool
|
owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
|
{
|
const struct xt_owner_match_info *info = par->matchinfo;
|
const struct file *filp;
|
struct sock *sk = skb_to_full_sk(skb);
|
struct net *net = xt_net(par);
|
|
if (!sk || !sk->sk_socket || !net_eq(net, sock_net(sk)))
|
return (info->match ^ info->invert) == 0;
|
else if (info->match & info->invert & XT_OWNER_SOCKET)
|
/*
|
* Socket exists but user wanted ! --socket-exists.
|
* (Single ampersands intended.)
|
*/
|
return false;
|
|
filp = sk->sk_socket->file;
|
if (filp == NULL)
|
return ((info->match ^ info->invert) &
|
(XT_OWNER_UID | XT_OWNER_GID)) == 0;
|
|
if (info->match & XT_OWNER_UID) {
|
kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);
|
kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);
|
if ((uid_gte(filp->f_cred->fsuid, uid_min) &&
|
uid_lte(filp->f_cred->fsuid, uid_max)) ^
|
!(info->invert & XT_OWNER_UID))
|
return false;
|
}
|
|
if (info->match & XT_OWNER_GID) {
|
unsigned int i, match = false;
|
kgid_t gid_min = make_kgid(net->user_ns, info->gid_min);
|
kgid_t gid_max = make_kgid(net->user_ns, info->gid_max);
|
struct group_info *gi = filp->f_cred->group_info;
|
|
if (gid_gte(filp->f_cred->fsgid, gid_min) &&
|
gid_lte(filp->f_cred->fsgid, gid_max))
|
match = true;
|
|
if (!match && (info->match & XT_OWNER_SUPPL_GROUPS) && gi) {
|
for (i = 0; i < gi->ngroups; ++i) {
|
kgid_t group = gi->gid[i];
|
|
if (gid_gte(group, gid_min) &&
|
gid_lte(group, gid_max)) {
|
match = true;
|
break;
|
}
|
}
|
}
|
|
if (match ^ !(info->invert & XT_OWNER_GID))
|
return false;
|
}
|
|
return true;
|
}
|
|
static struct xt_match owner_mt_reg __read_mostly = {
|
.name = "owner",
|
.revision = 1,
|
.family = NFPROTO_UNSPEC,
|
.checkentry = owner_check,
|
.match = owner_mt,
|
.matchsize = sizeof(struct xt_owner_match_info),
|
.hooks = (1 << NF_INET_LOCAL_OUT) |
|
(1 << NF_INET_POST_ROUTING),
|
.me = THIS_MODULE,
|
};
|
|
static int __init owner_mt_init(void)
|
{
|
return xt_register_match(&owner_mt_reg);
|
}
|
|
static void __exit owner_mt_exit(void)
|
{
|
xt_unregister_match(&owner_mt_reg);
|
}
|
|
module_init(owner_mt_init);
|
module_exit(owner_mt_exit);
|
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
|
MODULE_DESCRIPTION("Xtables: socket owner matching");
|
MODULE_LICENSE("GPL");
|
MODULE_ALIAS("ipt_owner");
|
MODULE_ALIAS("ip6t_owner");
|
