linux/net/ipv6/addrlabel.c
Johannes Berg 8cb081746c netlink: make validation more configurable for future strictness
We currently have two levels of strict validation:

 1) liberal (default)
     - undefined (type >= max) & NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted
     - garbage at end of message accepted
 2) strict (opt-in)
     - NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted

Split out parsing strictness into four different options:
 * TRAILING     - check that there's no trailing data after parsing
                  attributes (in message or nested)
 * MAXTYPE      - reject attrs > max known type
 * UNSPEC       - reject attributes with NLA_UNSPEC policy entries
 * STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
 * nla_parse           -> nla_parse_deprecated
 * nla_parse_strict    -> nla_parse_deprecated_strict
 * nlmsg_parse         -> nlmsg_parse_deprecated
 * nlmsg_parse_strict  -> nlmsg_parse_deprecated_strict
 * nla_parse_nested    -> nla_parse_nested_deprecated
 * nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
    @@
    expression TB, MAX, HEAD, LEN, POL, EXT;
    @@
    -nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
    +nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression TB, MAX, NLA, POL, EXT;
    @@
    -nla_parse_nested(TB, MAX, NLA, POL, EXT)
    +nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

    @@
    expression START, MAX, POL, EXT;
    @@
    -nla_validate_nested(START, MAX, POL, EXT)
    +nla_validate_nested_deprecated(START, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, MAX, POL, EXT;
    @@
    -nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
    +nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-27 17:07:21 -04:00

644 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* IPv6 Address Label subsystem
* for the IPv6 "Default" Source Address Selection
*
* Copyright (C)2007 USAGI/WIDE Project
*/
/*
* Author:
* YOSHIFUJI Hideaki @ USAGI/WIDE Project <yoshfuji@linux-ipv6.org>
*/
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/in6.h>
#include <linux/slab.h>
#include <net/addrconf.h>
#include <linux/if_addrlabel.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#if 0
#define ADDRLABEL(x...) printk(x)
#else
#define ADDRLABEL(x...) do { ; } while (0)
#endif
/*
* Policy Table
*/
struct ip6addrlbl_entry {
struct in6_addr prefix;
int prefixlen;
int ifindex;
int addrtype;
u32 label;
struct hlist_node list;
struct rcu_head rcu;
};
/*
* Default policy table (RFC6724 + extensions)
*
* prefix addr_type label
* -------------------------------------------------------------------------
* ::1/128 LOOPBACK 0
* ::/0 N/A 1
* 2002::/16 N/A 2
* ::/96 COMPATv4 3
* ::ffff:0:0/96 V4MAPPED 4
* fc00::/7 N/A 5 ULA (RFC 4193)
* 2001::/32 N/A 6 Teredo (RFC 4380)
* 2001:10::/28 N/A 7 ORCHID (RFC 4843)
* fec0::/10 N/A 11 Site-local
* (deprecated by RFC3879)
* 3ffe::/16 N/A 12 6bone
*
* Note: 0xffffffff is used if we do not have any policies.
* Note: Labels for ULA and 6to4 are different from labels listed in RFC6724.
*/
#define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL
static const __net_initconst struct ip6addrlbl_init_table
{
const struct in6_addr *prefix;
int prefixlen;
u32 label;
} ip6addrlbl_init_table[] = {
{ /* ::/0 */
.prefix = &in6addr_any,
.label = 1,
}, { /* fc00::/7 */
.prefix = &(struct in6_addr){ { { 0xfc } } } ,
.prefixlen = 7,
.label = 5,
}, { /* fec0::/10 */
.prefix = &(struct in6_addr){ { { 0xfe, 0xc0 } } },
.prefixlen = 10,
.label = 11,
}, { /* 2002::/16 */
.prefix = &(struct in6_addr){ { { 0x20, 0x02 } } },
.prefixlen = 16,
.label = 2,
}, { /* 3ffe::/16 */
.prefix = &(struct in6_addr){ { { 0x3f, 0xfe } } },
.prefixlen = 16,
.label = 12,
}, { /* 2001::/32 */
.prefix = &(struct in6_addr){ { { 0x20, 0x01 } } },
.prefixlen = 32,
.label = 6,
}, { /* 2001:10::/28 */
.prefix = &(struct in6_addr){ { { 0x20, 0x01, 0x00, 0x10 } } },
.prefixlen = 28,
.label = 7,
}, { /* ::ffff:0:0 */
.prefix = &(struct in6_addr){ { { [10] = 0xff, [11] = 0xff } } },
.prefixlen = 96,
.label = 4,
}, { /* ::/96 */
.prefix = &in6addr_any,
.prefixlen = 96,
.label = 3,
}, { /* ::1/128 */
.prefix = &in6addr_loopback,
.prefixlen = 128,
.label = 0,
}
};
/* Find label */
static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,
const struct in6_addr *addr,
int addrtype, int ifindex)
{
if (p->ifindex && p->ifindex != ifindex)
return false;
if (p->addrtype && p->addrtype != addrtype)
return false;
if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
return false;
return true;
}
static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
const struct in6_addr *addr,
int type, int ifindex)
{
struct ip6addrlbl_entry *p;
hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
if (__ip6addrlbl_match(p, addr, type, ifindex))
return p;
}
return NULL;
}
u32 ipv6_addr_label(struct net *net,
const struct in6_addr *addr, int type, int ifindex)
{
u32 label;
struct ip6addrlbl_entry *p;
type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
rcu_read_lock();
p = __ipv6_addr_label(net, addr, type, ifindex);
label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
rcu_read_unlock();
ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
__func__, addr, type, ifindex, label);
return label;
}
/* allocate one entry */
static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix,
int prefixlen, int ifindex,
u32 label)
{
struct ip6addrlbl_entry *newp;
int addrtype;
ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
__func__, prefix, prefixlen, ifindex, (unsigned int)label);
addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
switch (addrtype) {
case IPV6_ADDR_MAPPED:
if (prefixlen > 96)
return ERR_PTR(-EINVAL);
if (prefixlen < 96)
addrtype = 0;
break;
case IPV6_ADDR_COMPATv4:
if (prefixlen != 96)
addrtype = 0;
break;
case IPV6_ADDR_LOOPBACK:
if (prefixlen != 128)
addrtype = 0;
break;
}
newp = kmalloc(sizeof(*newp), GFP_KERNEL);
if (!newp)
return ERR_PTR(-ENOMEM);
ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
newp->prefixlen = prefixlen;
newp->ifindex = ifindex;
newp->addrtype = addrtype;
newp->label = label;
INIT_HLIST_NODE(&newp->list);
return newp;
}
/* add a label */
static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
int replace)
{
struct ip6addrlbl_entry *last = NULL, *p = NULL;
struct hlist_node *n;
int ret = 0;
ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n", __func__, newp,
replace);
hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
if (p->prefixlen == newp->prefixlen &&
p->ifindex == newp->ifindex &&
ipv6_addr_equal(&p->prefix, &newp->prefix)) {
if (!replace) {
ret = -EEXIST;
goto out;
}
hlist_replace_rcu(&p->list, &newp->list);
kfree_rcu(p, rcu);
goto out;
} else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
(p->prefixlen < newp->prefixlen)) {
hlist_add_before_rcu(&newp->list, &p->list);
goto out;
}
last = p;
}
if (last)
hlist_add_behind_rcu(&newp->list, &last->list);
else
hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
out:
if (!ret)
net->ipv6.ip6addrlbl_table.seq++;
return ret;
}
/* add a label */
static int ip6addrlbl_add(struct net *net,
const struct in6_addr *prefix, int prefixlen,
int ifindex, u32 label, int replace)
{
struct ip6addrlbl_entry *newp;
int ret = 0;
ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
__func__, prefix, prefixlen, ifindex, (unsigned int)label,
replace);
newp = ip6addrlbl_alloc(prefix, prefixlen, ifindex, label);
if (IS_ERR(newp))
return PTR_ERR(newp);
spin_lock(&net->ipv6.ip6addrlbl_table.lock);
ret = __ip6addrlbl_add(net, newp, replace);
spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
if (ret)
kfree(newp);
return ret;
}
/* remove a label */
static int __ip6addrlbl_del(struct net *net,
const struct in6_addr *prefix, int prefixlen,
int ifindex)
{
struct ip6addrlbl_entry *p = NULL;
struct hlist_node *n;
int ret = -ESRCH;
ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
__func__, prefix, prefixlen, ifindex);
hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
if (p->prefixlen == prefixlen &&
p->ifindex == ifindex &&
ipv6_addr_equal(&p->prefix, prefix)) {
hlist_del_rcu(&p->list);
kfree_rcu(p, rcu);
ret = 0;
break;
}
}
return ret;
}
static int ip6addrlbl_del(struct net *net,
const struct in6_addr *prefix, int prefixlen,
int ifindex)
{
struct in6_addr prefix_buf;
int ret;
ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
__func__, prefix, prefixlen, ifindex);
ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
spin_lock(&net->ipv6.ip6addrlbl_table.lock);
ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
return ret;
}
/* add default label */
static int __net_init ip6addrlbl_net_init(struct net *net)
{
int err = 0;
int i;
ADDRLABEL(KERN_DEBUG "%s\n", __func__);
spin_lock_init(&net->ipv6.ip6addrlbl_table.lock);
INIT_HLIST_HEAD(&net->ipv6.ip6addrlbl_table.head);
for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
int ret = ip6addrlbl_add(net,
ip6addrlbl_init_table[i].prefix,
ip6addrlbl_init_table[i].prefixlen,
0,
ip6addrlbl_init_table[i].label, 0);
/* XXX: should we free all rules when we catch an error? */
if (ret && (!err || err != -ENOMEM))
err = ret;
}
return err;
}
static void __net_exit ip6addrlbl_net_exit(struct net *net)
{
struct ip6addrlbl_entry *p = NULL;
struct hlist_node *n;
/* Remove all labels belonging to the exiting net */
spin_lock(&net->ipv6.ip6addrlbl_table.lock);
hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
hlist_del_rcu(&p->list);
kfree_rcu(p, rcu);
}
spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
}
static struct pernet_operations ipv6_addr_label_ops = {
.init = ip6addrlbl_net_init,
.exit = ip6addrlbl_net_exit,
};
int __init ipv6_addr_label_init(void)
{
return register_pernet_subsys(&ipv6_addr_label_ops);
}
void ipv6_addr_label_cleanup(void)
{
unregister_pernet_subsys(&ipv6_addr_label_ops);
}
static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
[IFAL_ADDRESS] = { .len = sizeof(struct in6_addr), },
[IFAL_LABEL] = { .len = sizeof(u32), },
};
static bool addrlbl_ifindex_exists(struct net *net, int ifindex)
{
struct net_device *dev;
rcu_read_lock();
dev = dev_get_by_index_rcu(net, ifindex);
rcu_read_unlock();
return dev != NULL;
}
static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
struct ifaddrlblmsg *ifal;
struct nlattr *tb[IFAL_MAX+1];
struct in6_addr *pfx;
u32 label;
int err = 0;
err = nlmsg_parse_deprecated(nlh, sizeof(*ifal), tb, IFAL_MAX,
ifal_policy, extack);
if (err < 0)
return err;
ifal = nlmsg_data(nlh);
if (ifal->ifal_family != AF_INET6 ||
ifal->ifal_prefixlen > 128)
return -EINVAL;
if (!tb[IFAL_ADDRESS])
return -EINVAL;
pfx = nla_data(tb[IFAL_ADDRESS]);
if (!tb[IFAL_LABEL])
return -EINVAL;
label = nla_get_u32(tb[IFAL_LABEL]);
if (label == IPV6_ADDR_LABEL_DEFAULT)
return -EINVAL;
switch (nlh->nlmsg_type) {
case RTM_NEWADDRLABEL:
if (ifal->ifal_index &&
!addrlbl_ifindex_exists(net, ifal->ifal_index))
return -EINVAL;
err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
ifal->ifal_index, label,
nlh->nlmsg_flags & NLM_F_REPLACE);
break;
case RTM_DELADDRLABEL:
err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
ifal->ifal_index);
break;
default:
err = -EOPNOTSUPP;
}
return err;
}
static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
int prefixlen, int ifindex, u32 lseq)
{
struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
ifal->ifal_family = AF_INET6;
ifal->ifal_prefixlen = prefixlen;
ifal->ifal_flags = 0;
ifal->ifal_index = ifindex;
ifal->ifal_seq = lseq;
};
static int ip6addrlbl_fill(struct sk_buff *skb,
struct ip6addrlbl_entry *p,
u32 lseq,
u32 portid, u32 seq, int event,
unsigned int flags)
{
struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
sizeof(struct ifaddrlblmsg), flags);
if (!nlh)
return -EMSGSIZE;
ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
if (nla_put_in6_addr(skb, IFAL_ADDRESS, &p->prefix) < 0 ||
nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
nlmsg_end(skb, nlh);
return 0;
}
static int ip6addrlbl_valid_dump_req(const struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct ifaddrlblmsg *ifal;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifal))) {
NL_SET_ERR_MSG_MOD(extack, "Invalid header for address label dump request");
return -EINVAL;
}
ifal = nlmsg_data(nlh);
if (ifal->__ifal_reserved || ifal->ifal_prefixlen ||
ifal->ifal_flags || ifal->ifal_index || ifal->ifal_seq) {
NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for address label dump request");
return -EINVAL;
}
if (nlmsg_attrlen(nlh, sizeof(*ifal))) {
NL_SET_ERR_MSG_MOD(extack, "Invalid data after header for address label dump request");
return -EINVAL;
}
return 0;
}
static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
const struct nlmsghdr *nlh = cb->nlh;
struct net *net = sock_net(skb->sk);
struct ip6addrlbl_entry *p;
int idx = 0, s_idx = cb->args[0];
int err;
if (cb->strict_check) {
err = ip6addrlbl_valid_dump_req(nlh, cb->extack);
if (err < 0)
return err;
}
rcu_read_lock();
hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
if (idx >= s_idx) {
err = ip6addrlbl_fill(skb, p,
net->ipv6.ip6addrlbl_table.seq,
NETLINK_CB(cb->skb).portid,
nlh->nlmsg_seq,
RTM_NEWADDRLABEL,
NLM_F_MULTI);
if (err < 0)
break;
}
idx++;
}
rcu_read_unlock();
cb->args[0] = idx;
return skb->len;
}
static inline int ip6addrlbl_msgsize(void)
{
return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
+ nla_total_size(16) /* IFAL_ADDRESS */
+ nla_total_size(4); /* IFAL_LABEL */
}
static int ip6addrlbl_valid_get_req(struct sk_buff *skb,
const struct nlmsghdr *nlh,
struct nlattr **tb,
struct netlink_ext_ack *extack)
{
struct ifaddrlblmsg *ifal;
int i, err;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifal))) {
NL_SET_ERR_MSG_MOD(extack, "Invalid header for addrlabel get request");
return -EINVAL;
}
if (!netlink_strict_get_check(skb))
return nlmsg_parse_deprecated(nlh, sizeof(*ifal), tb,
IFAL_MAX, ifal_policy, extack);
ifal = nlmsg_data(nlh);
if (ifal->__ifal_reserved || ifal->ifal_flags || ifal->ifal_seq) {
NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for addrlabel get request");
return -EINVAL;
}
err = nlmsg_parse_deprecated_strict(nlh, sizeof(*ifal), tb, IFAL_MAX,
ifal_policy, extack);
if (err)
return err;
for (i = 0; i <= IFAL_MAX; i++) {
if (!tb[i])
continue;
switch (i) {
case IFAL_ADDRESS:
break;
default:
NL_SET_ERR_MSG_MOD(extack, "Unsupported attribute in addrlabel get request");
return -EINVAL;
}
}
return 0;
}
static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(in_skb->sk);
struct ifaddrlblmsg *ifal;
struct nlattr *tb[IFAL_MAX+1];
struct in6_addr *addr;
u32 lseq;
int err = 0;
struct ip6addrlbl_entry *p;
struct sk_buff *skb;
err = ip6addrlbl_valid_get_req(in_skb, nlh, tb, extack);
if (err < 0)
return err;
ifal = nlmsg_data(nlh);
if (ifal->ifal_family != AF_INET6 ||
ifal->ifal_prefixlen != 128)
return -EINVAL;
if (ifal->ifal_index &&
!addrlbl_ifindex_exists(net, ifal->ifal_index))
return -EINVAL;
if (!tb[IFAL_ADDRESS])
return -EINVAL;
addr = nla_data(tb[IFAL_ADDRESS]);
skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
if (!skb)
return -ENOBUFS;
err = -ESRCH;
rcu_read_lock();
p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
lseq = net->ipv6.ip6addrlbl_table.seq;
if (p)
err = ip6addrlbl_fill(skb, p, lseq,
NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq,
RTM_NEWADDRLABEL, 0);
rcu_read_unlock();
if (err < 0) {
WARN_ON(err == -EMSGSIZE);
kfree_skb(skb);
} else {
err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
}
return err;
}
int __init ipv6_addr_label_rtnl_register(void)
{
int ret;
ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_NEWADDRLABEL,
ip6addrlbl_newdel,
NULL, RTNL_FLAG_DOIT_UNLOCKED);
if (ret < 0)
return ret;
ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_DELADDRLABEL,
ip6addrlbl_newdel,
NULL, RTNL_FLAG_DOIT_UNLOCKED);
if (ret < 0)
return ret;
ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,
ip6addrlbl_get,
ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED);
return ret;
}