linux/net/phonet/pn_netlink.c
Eric W. Biederman 90f62cf30a net: Use netlink_ns_capable to verify the permisions of netlink messages
It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-04-24 13:44:54 -04:00

313 lines
7.5 KiB
C

/*
* File: pn_netlink.c
*
* Phonet netlink interface
*
* Copyright (C) 2008 Nokia Corporation.
*
* Authors: Sakari Ailus <sakari.ailus@nokia.com>
* Remi Denis-Courmont
*
* 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.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include <linux/kernel.h>
#include <linux/netlink.h>
#include <linux/phonet.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/phonet/pn_dev.h>
/* Device address handling */
static int fill_addr(struct sk_buff *skb, struct net_device *dev, u8 addr,
u32 portid, u32 seq, int event);
void phonet_address_notify(int event, struct net_device *dev, u8 addr)
{
struct sk_buff *skb;
int err = -ENOBUFS;
skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
nla_total_size(1), GFP_KERNEL);
if (skb == NULL)
goto errout;
err = fill_addr(skb, dev, addr, 0, 0, event);
if (err < 0) {
WARN_ON(err == -EMSGSIZE);
kfree_skb(skb);
goto errout;
}
rtnl_notify(skb, dev_net(dev), 0,
RTNLGRP_PHONET_IFADDR, NULL, GFP_KERNEL);
return;
errout:
rtnl_set_sk_err(dev_net(dev), RTNLGRP_PHONET_IFADDR, err);
}
static const struct nla_policy ifa_phonet_policy[IFA_MAX+1] = {
[IFA_LOCAL] = { .type = NLA_U8 },
};
static int addr_doit(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[IFA_MAX+1];
struct net_device *dev;
struct ifaddrmsg *ifm;
int err;
u8 pnaddr;
if (!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
ASSERT_RTNL();
err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_phonet_policy);
if (err < 0)
return err;
ifm = nlmsg_data(nlh);
if (tb[IFA_LOCAL] == NULL)
return -EINVAL;
pnaddr = nla_get_u8(tb[IFA_LOCAL]);
if (pnaddr & 3)
/* Phonet addresses only have 6 high-order bits */
return -EINVAL;
dev = __dev_get_by_index(net, ifm->ifa_index);
if (dev == NULL)
return -ENODEV;
if (nlh->nlmsg_type == RTM_NEWADDR)
err = phonet_address_add(dev, pnaddr);
else
err = phonet_address_del(dev, pnaddr);
if (!err)
phonet_address_notify(nlh->nlmsg_type, dev, pnaddr);
return err;
}
static int fill_addr(struct sk_buff *skb, struct net_device *dev, u8 addr,
u32 portid, u32 seq, int event)
{
struct ifaddrmsg *ifm;
struct nlmsghdr *nlh;
nlh = nlmsg_put(skb, portid, seq, event, sizeof(*ifm), 0);
if (nlh == NULL)
return -EMSGSIZE;
ifm = nlmsg_data(nlh);
ifm->ifa_family = AF_PHONET;
ifm->ifa_prefixlen = 0;
ifm->ifa_flags = IFA_F_PERMANENT;
ifm->ifa_scope = RT_SCOPE_LINK;
ifm->ifa_index = dev->ifindex;
if (nla_put_u8(skb, IFA_LOCAL, addr))
goto nla_put_failure;
return nlmsg_end(skb, nlh);
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
static int getaddr_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
struct phonet_device_list *pndevs;
struct phonet_device *pnd;
int dev_idx = 0, dev_start_idx = cb->args[0];
int addr_idx = 0, addr_start_idx = cb->args[1];
pndevs = phonet_device_list(sock_net(skb->sk));
rcu_read_lock();
list_for_each_entry_rcu(pnd, &pndevs->list, list) {
u8 addr;
if (dev_idx > dev_start_idx)
addr_start_idx = 0;
if (dev_idx++ < dev_start_idx)
continue;
addr_idx = 0;
for_each_set_bit(addr, pnd->addrs, 64) {
if (addr_idx++ < addr_start_idx)
continue;
if (fill_addr(skb, pnd->netdev, addr << 2,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, RTM_NEWADDR) < 0)
goto out;
}
}
out:
rcu_read_unlock();
cb->args[0] = dev_idx;
cb->args[1] = addr_idx;
return skb->len;
}
/* Routes handling */
static int fill_route(struct sk_buff *skb, struct net_device *dev, u8 dst,
u32 portid, u32 seq, int event)
{
struct rtmsg *rtm;
struct nlmsghdr *nlh;
nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), 0);
if (nlh == NULL)
return -EMSGSIZE;
rtm = nlmsg_data(nlh);
rtm->rtm_family = AF_PHONET;
rtm->rtm_dst_len = 6;
rtm->rtm_src_len = 0;
rtm->rtm_tos = 0;
rtm->rtm_table = RT_TABLE_MAIN;
rtm->rtm_protocol = RTPROT_STATIC;
rtm->rtm_scope = RT_SCOPE_UNIVERSE;
rtm->rtm_type = RTN_UNICAST;
rtm->rtm_flags = 0;
if (nla_put_u8(skb, RTA_DST, dst) ||
nla_put_u32(skb, RTA_OIF, dev->ifindex))
goto nla_put_failure;
return nlmsg_end(skb, nlh);
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
void rtm_phonet_notify(int event, struct net_device *dev, u8 dst)
{
struct sk_buff *skb;
int err = -ENOBUFS;
skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
nla_total_size(1) + nla_total_size(4), GFP_KERNEL);
if (skb == NULL)
goto errout;
err = fill_route(skb, dev, dst, 0, 0, event);
if (err < 0) {
WARN_ON(err == -EMSGSIZE);
kfree_skb(skb);
goto errout;
}
rtnl_notify(skb, dev_net(dev), 0,
RTNLGRP_PHONET_ROUTE, NULL, GFP_KERNEL);
return;
errout:
rtnl_set_sk_err(dev_net(dev), RTNLGRP_PHONET_ROUTE, err);
}
static const struct nla_policy rtm_phonet_policy[RTA_MAX+1] = {
[RTA_DST] = { .type = NLA_U8 },
[RTA_OIF] = { .type = NLA_U32 },
};
static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[RTA_MAX+1];
struct net_device *dev;
struct rtmsg *rtm;
int err;
u8 dst;
if (!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
ASSERT_RTNL();
err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_phonet_policy);
if (err < 0)
return err;
rtm = nlmsg_data(nlh);
if (rtm->rtm_table != RT_TABLE_MAIN || rtm->rtm_type != RTN_UNICAST)
return -EINVAL;
if (tb[RTA_DST] == NULL || tb[RTA_OIF] == NULL)
return -EINVAL;
dst = nla_get_u8(tb[RTA_DST]);
if (dst & 3) /* Phonet addresses only have 6 high-order bits */
return -EINVAL;
dev = __dev_get_by_index(net, nla_get_u32(tb[RTA_OIF]));
if (dev == NULL)
return -ENODEV;
if (nlh->nlmsg_type == RTM_NEWROUTE)
err = phonet_route_add(dev, dst);
else
err = phonet_route_del(dev, dst);
if (!err)
rtm_phonet_notify(nlh->nlmsg_type, dev, dst);
return err;
}
static int route_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
u8 addr, addr_idx = 0, addr_start_idx = cb->args[0];
rcu_read_lock();
for (addr = 0; addr < 64; addr++) {
struct net_device *dev;
dev = phonet_route_get_rcu(net, addr << 2);
if (!dev)
continue;
if (addr_idx++ < addr_start_idx)
continue;
if (fill_route(skb, dev, addr << 2, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, RTM_NEWROUTE))
goto out;
}
out:
rcu_read_unlock();
cb->args[0] = addr_idx;
cb->args[1] = 0;
return skb->len;
}
int __init phonet_netlink_register(void)
{
int err = __rtnl_register(PF_PHONET, RTM_NEWADDR, addr_doit,
NULL, NULL);
if (err)
return err;
/* Further __rtnl_register() cannot fail */
__rtnl_register(PF_PHONET, RTM_DELADDR, addr_doit, NULL, NULL);
__rtnl_register(PF_PHONET, RTM_GETADDR, NULL, getaddr_dumpit, NULL);
__rtnl_register(PF_PHONET, RTM_NEWROUTE, route_doit, NULL, NULL);
__rtnl_register(PF_PHONET, RTM_DELROUTE, route_doit, NULL, NULL);
__rtnl_register(PF_PHONET, RTM_GETROUTE, NULL, route_dumpit, NULL);
return 0;
}