linux/net/xfrm/xfrm_policy.c
Trent Jaeger df71837d50 [LSM-IPSec]: Security association restriction.
This patch series implements per packet access control via the
extension of the Linux Security Modules (LSM) interface by hooks in
the XFRM and pfkey subsystems that leverage IPSec security
associations to label packets.  Extensions to the SELinux LSM are
included that leverage the patch for this purpose.

This patch implements the changes necessary to the XFRM subsystem,
pfkey interface, ipv4/ipv6, and xfrm_user interface to restrict a
socket to use only authorized security associations (or no security
association) to send/receive network packets.

Patch purpose:

The patch is designed to enable access control per packets based on
the strongly authenticated IPSec security association.  Such access
controls augment the existing ones based on network interface and IP
address.  The former are very coarse-grained, and the latter can be
spoofed.  By using IPSec, the system can control access to remote
hosts based on cryptographic keys generated using the IPSec mechanism.
This enables access control on a per-machine basis or per-application
if the remote machine is running the same mechanism and trusted to
enforce the access control policy.

Patch design approach:

The overall approach is that policy (xfrm_policy) entries set by
user-level programs (e.g., setkey for ipsec-tools) are extended with a
security context that is used at policy selection time in the XFRM
subsystem to restrict the sockets that can send/receive packets via
security associations (xfrm_states) that are built from those
policies.

A presentation available at
www.selinux-symposium.org/2005/presentations/session2/2-3-jaeger.pdf
from the SELinux symposium describes the overall approach.

Patch implementation details:

On output, the policy retrieved (via xfrm_policy_lookup or
xfrm_sk_policy_lookup) must be authorized for the security context of
the socket and the same security context is required for resultant
security association (retrieved or negotiated via racoon in
ipsec-tools).  This is enforced in xfrm_state_find.

On input, the policy retrieved must also be authorized for the socket
(at __xfrm_policy_check), and the security context of the policy must
also match the security association being used.

The patch has virtually no impact on packets that do not use IPSec.
The existing Netfilter (outgoing) and LSM rcv_skb hooks are used as
before.

Also, if IPSec is used without security contexts, the impact is
minimal.  The LSM must allow such policies to be selected for the
combination of socket and remote machine, but subsequent IPSec
processing proceeds as in the original case.

Testing:

The pfkey interface is tested using the ipsec-tools.  ipsec-tools have
been modified (a separate ipsec-tools patch is available for version
0.5) that supports assignment of xfrm_policy entries and security
associations with security contexts via setkey and the negotiation
using the security contexts via racoon.

The xfrm_user interface is tested via ad hoc programs that set
security contexts.  These programs are also available from me, and
contain programs for setting, getting, and deleting policy for testing
this interface.  Testing of sa functions was done by tracing kernel
behavior.

Signed-off-by: Trent Jaeger <tjaeger@cse.psu.edu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 13:10:24 -08:00

1361 lines
30 KiB
C

/*
* xfrm_policy.c
*
* Changes:
* Mitsuru KANDA @USAGI
* Kazunori MIYAZAWA @USAGI
* Kunihiro Ishiguro <kunihiro@ipinfusion.com>
* IPv6 support
* Kazunori MIYAZAWA @USAGI
* YOSHIFUJI Hideaki
* Split up af-specific portion
* Derek Atkins <derek@ihtfp.com> Add the post_input processor
*
*/
#include <asm/bug.h>
#include <linux/config.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/module.h>
#include <net/xfrm.h>
#include <net/ip.h>
DECLARE_MUTEX(xfrm_cfg_sem);
EXPORT_SYMBOL(xfrm_cfg_sem);
static DEFINE_RWLOCK(xfrm_policy_lock);
struct xfrm_policy *xfrm_policy_list[XFRM_POLICY_MAX*2];
EXPORT_SYMBOL(xfrm_policy_list);
static DEFINE_RWLOCK(xfrm_policy_afinfo_lock);
static struct xfrm_policy_afinfo *xfrm_policy_afinfo[NPROTO];
static kmem_cache_t *xfrm_dst_cache __read_mostly;
static struct work_struct xfrm_policy_gc_work;
static struct list_head xfrm_policy_gc_list =
LIST_HEAD_INIT(xfrm_policy_gc_list);
static DEFINE_SPINLOCK(xfrm_policy_gc_lock);
static struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family);
static void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo);
int xfrm_register_type(struct xfrm_type *type, unsigned short family)
{
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
struct xfrm_type_map *typemap;
int err = 0;
if (unlikely(afinfo == NULL))
return -EAFNOSUPPORT;
typemap = afinfo->type_map;
write_lock(&typemap->lock);
if (likely(typemap->map[type->proto] == NULL))
typemap->map[type->proto] = type;
else
err = -EEXIST;
write_unlock(&typemap->lock);
xfrm_policy_put_afinfo(afinfo);
return err;
}
EXPORT_SYMBOL(xfrm_register_type);
int xfrm_unregister_type(struct xfrm_type *type, unsigned short family)
{
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
struct xfrm_type_map *typemap;
int err = 0;
if (unlikely(afinfo == NULL))
return -EAFNOSUPPORT;
typemap = afinfo->type_map;
write_lock(&typemap->lock);
if (unlikely(typemap->map[type->proto] != type))
err = -ENOENT;
else
typemap->map[type->proto] = NULL;
write_unlock(&typemap->lock);
xfrm_policy_put_afinfo(afinfo);
return err;
}
EXPORT_SYMBOL(xfrm_unregister_type);
struct xfrm_type *xfrm_get_type(u8 proto, unsigned short family)
{
struct xfrm_policy_afinfo *afinfo;
struct xfrm_type_map *typemap;
struct xfrm_type *type;
int modload_attempted = 0;
retry:
afinfo = xfrm_policy_get_afinfo(family);
if (unlikely(afinfo == NULL))
return NULL;
typemap = afinfo->type_map;
read_lock(&typemap->lock);
type = typemap->map[proto];
if (unlikely(type && !try_module_get(type->owner)))
type = NULL;
read_unlock(&typemap->lock);
if (!type && !modload_attempted) {
xfrm_policy_put_afinfo(afinfo);
request_module("xfrm-type-%d-%d",
(int) family, (int) proto);
modload_attempted = 1;
goto retry;
}
xfrm_policy_put_afinfo(afinfo);
return type;
}
int xfrm_dst_lookup(struct xfrm_dst **dst, struct flowi *fl,
unsigned short family)
{
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
int err = 0;
if (unlikely(afinfo == NULL))
return -EAFNOSUPPORT;
if (likely(afinfo->dst_lookup != NULL))
err = afinfo->dst_lookup(dst, fl);
else
err = -EINVAL;
xfrm_policy_put_afinfo(afinfo);
return err;
}
EXPORT_SYMBOL(xfrm_dst_lookup);
void xfrm_put_type(struct xfrm_type *type)
{
module_put(type->owner);
}
static inline unsigned long make_jiffies(long secs)
{
if (secs >= (MAX_SCHEDULE_TIMEOUT-1)/HZ)
return MAX_SCHEDULE_TIMEOUT-1;
else
return secs*HZ;
}
static void xfrm_policy_timer(unsigned long data)
{
struct xfrm_policy *xp = (struct xfrm_policy*)data;
unsigned long now = (unsigned long)xtime.tv_sec;
long next = LONG_MAX;
int warn = 0;
int dir;
read_lock(&xp->lock);
if (xp->dead)
goto out;
dir = xfrm_policy_id2dir(xp->index);
if (xp->lft.hard_add_expires_seconds) {
long tmo = xp->lft.hard_add_expires_seconds +
xp->curlft.add_time - now;
if (tmo <= 0)
goto expired;
if (tmo < next)
next = tmo;
}
if (xp->lft.hard_use_expires_seconds) {
long tmo = xp->lft.hard_use_expires_seconds +
(xp->curlft.use_time ? : xp->curlft.add_time) - now;
if (tmo <= 0)
goto expired;
if (tmo < next)
next = tmo;
}
if (xp->lft.soft_add_expires_seconds) {
long tmo = xp->lft.soft_add_expires_seconds +
xp->curlft.add_time - now;
if (tmo <= 0) {
warn = 1;
tmo = XFRM_KM_TIMEOUT;
}
if (tmo < next)
next = tmo;
}
if (xp->lft.soft_use_expires_seconds) {
long tmo = xp->lft.soft_use_expires_seconds +
(xp->curlft.use_time ? : xp->curlft.add_time) - now;
if (tmo <= 0) {
warn = 1;
tmo = XFRM_KM_TIMEOUT;
}
if (tmo < next)
next = tmo;
}
if (warn)
km_policy_expired(xp, dir, 0);
if (next != LONG_MAX &&
!mod_timer(&xp->timer, jiffies + make_jiffies(next)))
xfrm_pol_hold(xp);
out:
read_unlock(&xp->lock);
xfrm_pol_put(xp);
return;
expired:
read_unlock(&xp->lock);
if (!xfrm_policy_delete(xp, dir))
km_policy_expired(xp, dir, 1);
xfrm_pol_put(xp);
}
/* Allocate xfrm_policy. Not used here, it is supposed to be used by pfkeyv2
* SPD calls.
*/
struct xfrm_policy *xfrm_policy_alloc(gfp_t gfp)
{
struct xfrm_policy *policy;
policy = kmalloc(sizeof(struct xfrm_policy), gfp);
if (policy) {
memset(policy, 0, sizeof(struct xfrm_policy));
atomic_set(&policy->refcnt, 1);
rwlock_init(&policy->lock);
init_timer(&policy->timer);
policy->timer.data = (unsigned long)policy;
policy->timer.function = xfrm_policy_timer;
}
return policy;
}
EXPORT_SYMBOL(xfrm_policy_alloc);
/* Destroy xfrm_policy: descendant resources must be released to this moment. */
void __xfrm_policy_destroy(struct xfrm_policy *policy)
{
if (!policy->dead)
BUG();
if (policy->bundles)
BUG();
if (del_timer(&policy->timer))
BUG();
security_xfrm_policy_free(policy);
kfree(policy);
}
EXPORT_SYMBOL(__xfrm_policy_destroy);
static void xfrm_policy_gc_kill(struct xfrm_policy *policy)
{
struct dst_entry *dst;
while ((dst = policy->bundles) != NULL) {
policy->bundles = dst->next;
dst_free(dst);
}
if (del_timer(&policy->timer))
atomic_dec(&policy->refcnt);
if (atomic_read(&policy->refcnt) > 1)
flow_cache_flush();
xfrm_pol_put(policy);
}
static void xfrm_policy_gc_task(void *data)
{
struct xfrm_policy *policy;
struct list_head *entry, *tmp;
struct list_head gc_list = LIST_HEAD_INIT(gc_list);
spin_lock_bh(&xfrm_policy_gc_lock);
list_splice_init(&xfrm_policy_gc_list, &gc_list);
spin_unlock_bh(&xfrm_policy_gc_lock);
list_for_each_safe(entry, tmp, &gc_list) {
policy = list_entry(entry, struct xfrm_policy, list);
xfrm_policy_gc_kill(policy);
}
}
/* Rule must be locked. Release descentant resources, announce
* entry dead. The rule must be unlinked from lists to the moment.
*/
static void xfrm_policy_kill(struct xfrm_policy *policy)
{
int dead;
write_lock_bh(&policy->lock);
dead = policy->dead;
policy->dead = 1;
write_unlock_bh(&policy->lock);
if (unlikely(dead)) {
WARN_ON(1);
return;
}
spin_lock(&xfrm_policy_gc_lock);
list_add(&policy->list, &xfrm_policy_gc_list);
spin_unlock(&xfrm_policy_gc_lock);
schedule_work(&xfrm_policy_gc_work);
}
/* Generate new index... KAME seems to generate them ordered by cost
* of an absolute inpredictability of ordering of rules. This will not pass. */
static u32 xfrm_gen_index(int dir)
{
u32 idx;
struct xfrm_policy *p;
static u32 idx_generator;
for (;;) {
idx = (idx_generator | dir);
idx_generator += 8;
if (idx == 0)
idx = 8;
for (p = xfrm_policy_list[dir]; p; p = p->next) {
if (p->index == idx)
break;
}
if (!p)
return idx;
}
}
int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
{
struct xfrm_policy *pol, **p;
struct xfrm_policy *delpol = NULL;
struct xfrm_policy **newpos = NULL;
struct dst_entry *gc_list;
write_lock_bh(&xfrm_policy_lock);
for (p = &xfrm_policy_list[dir]; (pol=*p)!=NULL;) {
if (!delpol && memcmp(&policy->selector, &pol->selector, sizeof(pol->selector)) == 0 &&
xfrm_sec_ctx_match(pol->security, policy->security)) {
if (excl) {
write_unlock_bh(&xfrm_policy_lock);
return -EEXIST;
}
*p = pol->next;
delpol = pol;
if (policy->priority > pol->priority)
continue;
} else if (policy->priority >= pol->priority) {
p = &pol->next;
continue;
}
if (!newpos)
newpos = p;
if (delpol)
break;
p = &pol->next;
}
if (newpos)
p = newpos;
xfrm_pol_hold(policy);
policy->next = *p;
*p = policy;
atomic_inc(&flow_cache_genid);
policy->index = delpol ? delpol->index : xfrm_gen_index(dir);
policy->curlft.add_time = (unsigned long)xtime.tv_sec;
policy->curlft.use_time = 0;
if (!mod_timer(&policy->timer, jiffies + HZ))
xfrm_pol_hold(policy);
write_unlock_bh(&xfrm_policy_lock);
if (delpol)
xfrm_policy_kill(delpol);
read_lock_bh(&xfrm_policy_lock);
gc_list = NULL;
for (policy = policy->next; policy; policy = policy->next) {
struct dst_entry *dst;
write_lock(&policy->lock);
dst = policy->bundles;
if (dst) {
struct dst_entry *tail = dst;
while (tail->next)
tail = tail->next;
tail->next = gc_list;
gc_list = dst;
policy->bundles = NULL;
}
write_unlock(&policy->lock);
}
read_unlock_bh(&xfrm_policy_lock);
while (gc_list) {
struct dst_entry *dst = gc_list;
gc_list = dst->next;
dst_free(dst);
}
return 0;
}
EXPORT_SYMBOL(xfrm_policy_insert);
struct xfrm_policy *xfrm_policy_bysel_ctx(int dir, struct xfrm_selector *sel,
struct xfrm_sec_ctx *ctx, int delete)
{
struct xfrm_policy *pol, **p;
write_lock_bh(&xfrm_policy_lock);
for (p = &xfrm_policy_list[dir]; (pol=*p)!=NULL; p = &pol->next) {
if ((memcmp(sel, &pol->selector, sizeof(*sel)) == 0) &&
(xfrm_sec_ctx_match(ctx, pol->security))) {
xfrm_pol_hold(pol);
if (delete)
*p = pol->next;
break;
}
}
write_unlock_bh(&xfrm_policy_lock);
if (pol && delete) {
atomic_inc(&flow_cache_genid);
xfrm_policy_kill(pol);
}
return pol;
}
EXPORT_SYMBOL(xfrm_policy_bysel_ctx);
struct xfrm_policy *xfrm_policy_byid(int dir, u32 id, int delete)
{
struct xfrm_policy *pol, **p;
write_lock_bh(&xfrm_policy_lock);
for (p = &xfrm_policy_list[dir]; (pol=*p)!=NULL; p = &pol->next) {
if (pol->index == id) {
xfrm_pol_hold(pol);
if (delete)
*p = pol->next;
break;
}
}
write_unlock_bh(&xfrm_policy_lock);
if (pol && delete) {
atomic_inc(&flow_cache_genid);
xfrm_policy_kill(pol);
}
return pol;
}
EXPORT_SYMBOL(xfrm_policy_byid);
void xfrm_policy_flush(void)
{
struct xfrm_policy *xp;
int dir;
write_lock_bh(&xfrm_policy_lock);
for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
while ((xp = xfrm_policy_list[dir]) != NULL) {
xfrm_policy_list[dir] = xp->next;
write_unlock_bh(&xfrm_policy_lock);
xfrm_policy_kill(xp);
write_lock_bh(&xfrm_policy_lock);
}
}
atomic_inc(&flow_cache_genid);
write_unlock_bh(&xfrm_policy_lock);
}
EXPORT_SYMBOL(xfrm_policy_flush);
int xfrm_policy_walk(int (*func)(struct xfrm_policy *, int, int, void*),
void *data)
{
struct xfrm_policy *xp;
int dir;
int count = 0;
int error = 0;
read_lock_bh(&xfrm_policy_lock);
for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
for (xp = xfrm_policy_list[dir]; xp; xp = xp->next)
count++;
}
if (count == 0) {
error = -ENOENT;
goto out;
}
for (dir = 0; dir < 2*XFRM_POLICY_MAX; dir++) {
for (xp = xfrm_policy_list[dir]; xp; xp = xp->next) {
error = func(xp, dir%XFRM_POLICY_MAX, --count, data);
if (error)
goto out;
}
}
out:
read_unlock_bh(&xfrm_policy_lock);
return error;
}
EXPORT_SYMBOL(xfrm_policy_walk);
/* Find policy to apply to this flow. */
static void xfrm_policy_lookup(struct flowi *fl, u32 sk_sid, u16 family, u8 dir,
void **objp, atomic_t **obj_refp)
{
struct xfrm_policy *pol;
read_lock_bh(&xfrm_policy_lock);
for (pol = xfrm_policy_list[dir]; pol; pol = pol->next) {
struct xfrm_selector *sel = &pol->selector;
int match;
if (pol->family != family)
continue;
match = xfrm_selector_match(sel, fl, family);
if (match) {
if (!security_xfrm_policy_lookup(pol, sk_sid, dir)) {
xfrm_pol_hold(pol);
break;
}
}
}
read_unlock_bh(&xfrm_policy_lock);
if ((*objp = (void *) pol) != NULL)
*obj_refp = &pol->refcnt;
}
static inline int policy_to_flow_dir(int dir)
{
if (XFRM_POLICY_IN == FLOW_DIR_IN &&
XFRM_POLICY_OUT == FLOW_DIR_OUT &&
XFRM_POLICY_FWD == FLOW_DIR_FWD)
return dir;
switch (dir) {
default:
case XFRM_POLICY_IN:
return FLOW_DIR_IN;
case XFRM_POLICY_OUT:
return FLOW_DIR_OUT;
case XFRM_POLICY_FWD:
return FLOW_DIR_FWD;
};
}
static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struct flowi *fl, u32 sk_sid)
{
struct xfrm_policy *pol;
read_lock_bh(&xfrm_policy_lock);
if ((pol = sk->sk_policy[dir]) != NULL) {
int match = xfrm_selector_match(&pol->selector, fl,
sk->sk_family);
int err = 0;
if (match)
err = security_xfrm_policy_lookup(pol, sk_sid, policy_to_flow_dir(dir));
if (match && !err)
xfrm_pol_hold(pol);
else
pol = NULL;
}
read_unlock_bh(&xfrm_policy_lock);
return pol;
}
static void __xfrm_policy_link(struct xfrm_policy *pol, int dir)
{
pol->next = xfrm_policy_list[dir];
xfrm_policy_list[dir] = pol;
xfrm_pol_hold(pol);
}
static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
int dir)
{
struct xfrm_policy **polp;
for (polp = &xfrm_policy_list[dir];
*polp != NULL; polp = &(*polp)->next) {
if (*polp == pol) {
*polp = pol->next;
return pol;
}
}
return NULL;
}
int xfrm_policy_delete(struct xfrm_policy *pol, int dir)
{
write_lock_bh(&xfrm_policy_lock);
pol = __xfrm_policy_unlink(pol, dir);
write_unlock_bh(&xfrm_policy_lock);
if (pol) {
if (dir < XFRM_POLICY_MAX)
atomic_inc(&flow_cache_genid);
xfrm_policy_kill(pol);
return 0;
}
return -ENOENT;
}
int xfrm_sk_policy_insert(struct sock *sk, int dir, struct xfrm_policy *pol)
{
struct xfrm_policy *old_pol;
write_lock_bh(&xfrm_policy_lock);
old_pol = sk->sk_policy[dir];
sk->sk_policy[dir] = pol;
if (pol) {
pol->curlft.add_time = (unsigned long)xtime.tv_sec;
pol->index = xfrm_gen_index(XFRM_POLICY_MAX+dir);
__xfrm_policy_link(pol, XFRM_POLICY_MAX+dir);
}
if (old_pol)
__xfrm_policy_unlink(old_pol, XFRM_POLICY_MAX+dir);
write_unlock_bh(&xfrm_policy_lock);
if (old_pol) {
xfrm_policy_kill(old_pol);
}
return 0;
}
static struct xfrm_policy *clone_policy(struct xfrm_policy *old, int dir)
{
struct xfrm_policy *newp = xfrm_policy_alloc(GFP_ATOMIC);
if (newp) {
newp->selector = old->selector;
if (security_xfrm_policy_clone(old, newp)) {
kfree(newp);
return NULL; /* ENOMEM */
}
newp->lft = old->lft;
newp->curlft = old->curlft;
newp->action = old->action;
newp->flags = old->flags;
newp->xfrm_nr = old->xfrm_nr;
newp->index = old->index;
memcpy(newp->xfrm_vec, old->xfrm_vec,
newp->xfrm_nr*sizeof(struct xfrm_tmpl));
write_lock_bh(&xfrm_policy_lock);
__xfrm_policy_link(newp, XFRM_POLICY_MAX+dir);
write_unlock_bh(&xfrm_policy_lock);
xfrm_pol_put(newp);
}
return newp;
}
int __xfrm_sk_clone_policy(struct sock *sk)
{
struct xfrm_policy *p0 = sk->sk_policy[0],
*p1 = sk->sk_policy[1];
sk->sk_policy[0] = sk->sk_policy[1] = NULL;
if (p0 && (sk->sk_policy[0] = clone_policy(p0, 0)) == NULL)
return -ENOMEM;
if (p1 && (sk->sk_policy[1] = clone_policy(p1, 1)) == NULL)
return -ENOMEM;
return 0;
}
/* Resolve list of templates for the flow, given policy. */
static int
xfrm_tmpl_resolve(struct xfrm_policy *policy, struct flowi *fl,
struct xfrm_state **xfrm,
unsigned short family)
{
int nx;
int i, error;
xfrm_address_t *daddr = xfrm_flowi_daddr(fl, family);
xfrm_address_t *saddr = xfrm_flowi_saddr(fl, family);
for (nx=0, i = 0; i < policy->xfrm_nr; i++) {
struct xfrm_state *x;
xfrm_address_t *remote = daddr;
xfrm_address_t *local = saddr;
struct xfrm_tmpl *tmpl = &policy->xfrm_vec[i];
if (tmpl->mode) {
remote = &tmpl->id.daddr;
local = &tmpl->saddr;
}
x = xfrm_state_find(remote, local, fl, tmpl, policy, &error, family);
if (x && x->km.state == XFRM_STATE_VALID) {
xfrm[nx++] = x;
daddr = remote;
saddr = local;
continue;
}
if (x) {
error = (x->km.state == XFRM_STATE_ERROR ?
-EINVAL : -EAGAIN);
xfrm_state_put(x);
}
if (!tmpl->optional)
goto fail;
}
return nx;
fail:
for (nx--; nx>=0; nx--)
xfrm_state_put(xfrm[nx]);
return error;
}
/* Check that the bundle accepts the flow and its components are
* still valid.
*/
static struct dst_entry *
xfrm_find_bundle(struct flowi *fl, struct xfrm_policy *policy, unsigned short family)
{
struct dst_entry *x;
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
if (unlikely(afinfo == NULL))
return ERR_PTR(-EINVAL);
x = afinfo->find_bundle(fl, policy);
xfrm_policy_put_afinfo(afinfo);
return x;
}
/* Allocate chain of dst_entry's, attach known xfrm's, calculate
* all the metrics... Shortly, bundle a bundle.
*/
static int
xfrm_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
struct flowi *fl, struct dst_entry **dst_p,
unsigned short family)
{
int err;
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
if (unlikely(afinfo == NULL))
return -EINVAL;
err = afinfo->bundle_create(policy, xfrm, nx, fl, dst_p);
xfrm_policy_put_afinfo(afinfo);
return err;
}
static int stale_bundle(struct dst_entry *dst);
/* Main function: finds/creates a bundle for given flow.
*
* At the moment we eat a raw IP route. Mostly to speed up lookups
* on interfaces with disabled IPsec.
*/
int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
struct sock *sk, int flags)
{
struct xfrm_policy *policy;
struct xfrm_state *xfrm[XFRM_MAX_DEPTH];
struct dst_entry *dst, *dst_orig = *dst_p;
int nx = 0;
int err;
u32 genid;
u16 family = dst_orig->ops->family;
u8 dir = policy_to_flow_dir(XFRM_POLICY_OUT);
u32 sk_sid = security_sk_sid(sk, fl, dir);
restart:
genid = atomic_read(&flow_cache_genid);
policy = NULL;
if (sk && sk->sk_policy[1])
policy = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl, sk_sid);
if (!policy) {
/* To accelerate a bit... */
if ((dst_orig->flags & DST_NOXFRM) || !xfrm_policy_list[XFRM_POLICY_OUT])
return 0;
policy = flow_cache_lookup(fl, sk_sid, family, dir,
xfrm_policy_lookup);
}
if (!policy)
return 0;
policy->curlft.use_time = (unsigned long)xtime.tv_sec;
switch (policy->action) {
case XFRM_POLICY_BLOCK:
/* Prohibit the flow */
err = -EPERM;
goto error;
case XFRM_POLICY_ALLOW:
if (policy->xfrm_nr == 0) {
/* Flow passes not transformed. */
xfrm_pol_put(policy);
return 0;
}
/* Try to find matching bundle.
*
* LATER: help from flow cache. It is optional, this
* is required only for output policy.
*/
dst = xfrm_find_bundle(fl, policy, family);
if (IS_ERR(dst)) {
err = PTR_ERR(dst);
goto error;
}
if (dst)
break;
nx = xfrm_tmpl_resolve(policy, fl, xfrm, family);
if (unlikely(nx<0)) {
err = nx;
if (err == -EAGAIN && flags) {
DECLARE_WAITQUEUE(wait, current);
add_wait_queue(&km_waitq, &wait);
set_current_state(TASK_INTERRUPTIBLE);
schedule();
set_current_state(TASK_RUNNING);
remove_wait_queue(&km_waitq, &wait);
nx = xfrm_tmpl_resolve(policy, fl, xfrm, family);
if (nx == -EAGAIN && signal_pending(current)) {
err = -ERESTART;
goto error;
}
if (nx == -EAGAIN ||
genid != atomic_read(&flow_cache_genid)) {
xfrm_pol_put(policy);
goto restart;
}
err = nx;
}
if (err < 0)
goto error;
}
if (nx == 0) {
/* Flow passes not transformed. */
xfrm_pol_put(policy);
return 0;
}
dst = dst_orig;
err = xfrm_bundle_create(policy, xfrm, nx, fl, &dst, family);
if (unlikely(err)) {
int i;
for (i=0; i<nx; i++)
xfrm_state_put(xfrm[i]);
goto error;
}
write_lock_bh(&policy->lock);
if (unlikely(policy->dead || stale_bundle(dst))) {
/* Wow! While we worked on resolving, this
* policy has gone. Retry. It is not paranoia,
* we just cannot enlist new bundle to dead object.
* We can't enlist stable bundles either.
*/
write_unlock_bh(&policy->lock);
xfrm_pol_put(policy);
if (dst)
dst_free(dst);
goto restart;
}
dst->next = policy->bundles;
policy->bundles = dst;
dst_hold(dst);
write_unlock_bh(&policy->lock);
}
*dst_p = dst;
dst_release(dst_orig);
xfrm_pol_put(policy);
return 0;
error:
dst_release(dst_orig);
xfrm_pol_put(policy);
*dst_p = NULL;
return err;
}
EXPORT_SYMBOL(xfrm_lookup);
/* When skb is transformed back to its "native" form, we have to
* check policy restrictions. At the moment we make this in maximally
* stupid way. Shame on me. :-) Of course, connected sockets must
* have policy cached at them.
*/
static inline int
xfrm_state_ok(struct xfrm_tmpl *tmpl, struct xfrm_state *x,
unsigned short family)
{
if (xfrm_state_kern(x))
return tmpl->optional && !xfrm_state_addr_cmp(tmpl, x, family);
return x->id.proto == tmpl->id.proto &&
(x->id.spi == tmpl->id.spi || !tmpl->id.spi) &&
(x->props.reqid == tmpl->reqid || !tmpl->reqid) &&
x->props.mode == tmpl->mode &&
(tmpl->aalgos & (1<<x->props.aalgo)) &&
!(x->props.mode && xfrm_state_addr_cmp(tmpl, x, family));
}
static inline int
xfrm_policy_ok(struct xfrm_tmpl *tmpl, struct sec_path *sp, int start,
unsigned short family)
{
int idx = start;
if (tmpl->optional) {
if (!tmpl->mode)
return start;
} else
start = -1;
for (; idx < sp->len; idx++) {
if (xfrm_state_ok(tmpl, sp->x[idx].xvec, family))
return ++idx;
if (sp->x[idx].xvec->props.mode)
break;
}
return start;
}
static int
_decode_session(struct sk_buff *skb, struct flowi *fl, unsigned short family)
{
struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
if (unlikely(afinfo == NULL))
return -EAFNOSUPPORT;
afinfo->decode_session(skb, fl);
xfrm_policy_put_afinfo(afinfo);
return 0;
}
static inline int secpath_has_tunnel(struct sec_path *sp, int k)
{
for (; k < sp->len; k++) {
if (sp->x[k].xvec->props.mode)
return 1;
}
return 0;
}
int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
unsigned short family)
{
struct xfrm_policy *pol;
struct flowi fl;
u8 fl_dir = policy_to_flow_dir(dir);
u32 sk_sid;
if (_decode_session(skb, &fl, family) < 0)
return 0;
sk_sid = security_sk_sid(sk, &fl, fl_dir);
/* First, check used SA against their selectors. */
if (skb->sp) {
int i;
for (i=skb->sp->len-1; i>=0; i--) {
struct sec_decap_state *xvec = &(skb->sp->x[i]);
if (!xfrm_selector_match(&xvec->xvec->sel, &fl, family))
return 0;
/* If there is a post_input processor, try running it */
if (xvec->xvec->type->post_input &&
(xvec->xvec->type->post_input)(xvec->xvec,
&(xvec->decap),
skb) != 0)
return 0;
}
}
pol = NULL;
if (sk && sk->sk_policy[dir])
pol = xfrm_sk_policy_lookup(sk, dir, &fl, sk_sid);
if (!pol)
pol = flow_cache_lookup(&fl, sk_sid, family, fl_dir,
xfrm_policy_lookup);
if (!pol)
return !skb->sp || !secpath_has_tunnel(skb->sp, 0);
pol->curlft.use_time = (unsigned long)xtime.tv_sec;
if (pol->action == XFRM_POLICY_ALLOW) {
struct sec_path *sp;
static struct sec_path dummy;
int i, k;
if ((sp = skb->sp) == NULL)
sp = &dummy;
/* For each tunnel xfrm, find the first matching tmpl.
* For each tmpl before that, find corresponding xfrm.
* Order is _important_. Later we will implement
* some barriers, but at the moment barriers
* are implied between each two transformations.
*/
for (i = pol->xfrm_nr-1, k = 0; i >= 0; i--) {
k = xfrm_policy_ok(pol->xfrm_vec+i, sp, k, family);
if (k < 0)
goto reject;
}
if (secpath_has_tunnel(sp, k))
goto reject;
xfrm_pol_put(pol);
return 1;
}
reject:
xfrm_pol_put(pol);
return 0;
}
EXPORT_SYMBOL(__xfrm_policy_check);
int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
{
struct flowi fl;
if (_decode_session(skb, &fl, family) < 0)
return 0;
return xfrm_lookup(&skb->dst, &fl, NULL, 0) == 0;
}
EXPORT_SYMBOL(__xfrm_route_forward);
static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
{
/* If it is marked obsolete, which is how we even get here,
* then we have purged it from the policy bundle list and we
* did that for a good reason.
*/
return NULL;
}
static int stale_bundle(struct dst_entry *dst)
{
return !xfrm_bundle_ok((struct xfrm_dst *)dst, NULL, AF_UNSPEC);
}
void xfrm_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
{
while ((dst = dst->child) && dst->xfrm && dst->dev == dev) {
dst->dev = &loopback_dev;
dev_hold(&loopback_dev);
dev_put(dev);
}
}
EXPORT_SYMBOL(xfrm_dst_ifdown);
static void xfrm_link_failure(struct sk_buff *skb)
{
/* Impossible. Such dst must be popped before reaches point of failure. */
return;
}
static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst)
{
if (dst) {
if (dst->obsolete) {
dst_release(dst);
dst = NULL;
}
}
return dst;
}
static void xfrm_prune_bundles(int (*func)(struct dst_entry *))
{
int i;
struct xfrm_policy *pol;
struct dst_entry *dst, **dstp, *gc_list = NULL;
read_lock_bh(&xfrm_policy_lock);
for (i=0; i<2*XFRM_POLICY_MAX; i++) {
for (pol = xfrm_policy_list[i]; pol; pol = pol->next) {
write_lock(&pol->lock);
dstp = &pol->bundles;
while ((dst=*dstp) != NULL) {
if (func(dst)) {
*dstp = dst->next;
dst->next = gc_list;
gc_list = dst;
} else {
dstp = &dst->next;
}
}
write_unlock(&pol->lock);
}
}
read_unlock_bh(&xfrm_policy_lock);
while (gc_list) {
dst = gc_list;
gc_list = dst->next;
dst_free(dst);
}
}
static int unused_bundle(struct dst_entry *dst)
{
return !atomic_read(&dst->__refcnt);
}
static void __xfrm_garbage_collect(void)
{
xfrm_prune_bundles(unused_bundle);
}
int xfrm_flush_bundles(void)
{
xfrm_prune_bundles(stale_bundle);
return 0;
}
static int always_true(struct dst_entry *dst)
{
return 1;
}
void xfrm_flush_all_bundles(void)
{
xfrm_prune_bundles(always_true);
}
void xfrm_init_pmtu(struct dst_entry *dst)
{
do {
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
u32 pmtu, route_mtu_cached;
pmtu = dst_mtu(dst->child);
xdst->child_mtu_cached = pmtu;
pmtu = xfrm_state_mtu(dst->xfrm, pmtu);
route_mtu_cached = dst_mtu(xdst->route);
xdst->route_mtu_cached = route_mtu_cached;
if (pmtu > route_mtu_cached)
pmtu = route_mtu_cached;
dst->metrics[RTAX_MTU-1] = pmtu;
} while ((dst = dst->next));
}
EXPORT_SYMBOL(xfrm_init_pmtu);
/* Check that the bundle accepts the flow and its components are
* still valid.
*/
int xfrm_bundle_ok(struct xfrm_dst *first, struct flowi *fl, int family)
{
struct dst_entry *dst = &first->u.dst;
struct xfrm_dst *last;
u32 mtu;
if (!dst_check(dst->path, ((struct xfrm_dst *)dst)->path_cookie) ||
(dst->dev && !netif_running(dst->dev)))
return 0;
last = NULL;
do {
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
if (fl && !xfrm_selector_match(&dst->xfrm->sel, fl, family))
return 0;
if (dst->xfrm->km.state != XFRM_STATE_VALID)
return 0;
mtu = dst_mtu(dst->child);
if (xdst->child_mtu_cached != mtu) {
last = xdst;
xdst->child_mtu_cached = mtu;
}
if (!dst_check(xdst->route, xdst->route_cookie))
return 0;
mtu = dst_mtu(xdst->route);
if (xdst->route_mtu_cached != mtu) {
last = xdst;
xdst->route_mtu_cached = mtu;
}
dst = dst->child;
} while (dst->xfrm);
if (likely(!last))
return 1;
mtu = last->child_mtu_cached;
for (;;) {
dst = &last->u.dst;
mtu = xfrm_state_mtu(dst->xfrm, mtu);
if (mtu > last->route_mtu_cached)
mtu = last->route_mtu_cached;
dst->metrics[RTAX_MTU-1] = mtu;
if (last == first)
break;
last = last->u.next;
last->child_mtu_cached = mtu;
}
return 1;
}
EXPORT_SYMBOL(xfrm_bundle_ok);
int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
{
int err = 0;
if (unlikely(afinfo == NULL))
return -EINVAL;
if (unlikely(afinfo->family >= NPROTO))
return -EAFNOSUPPORT;
write_lock(&xfrm_policy_afinfo_lock);
if (unlikely(xfrm_policy_afinfo[afinfo->family] != NULL))
err = -ENOBUFS;
else {
struct dst_ops *dst_ops = afinfo->dst_ops;
if (likely(dst_ops->kmem_cachep == NULL))
dst_ops->kmem_cachep = xfrm_dst_cache;
if (likely(dst_ops->check == NULL))
dst_ops->check = xfrm_dst_check;
if (likely(dst_ops->negative_advice == NULL))
dst_ops->negative_advice = xfrm_negative_advice;
if (likely(dst_ops->link_failure == NULL))
dst_ops->link_failure = xfrm_link_failure;
if (likely(afinfo->garbage_collect == NULL))
afinfo->garbage_collect = __xfrm_garbage_collect;
xfrm_policy_afinfo[afinfo->family] = afinfo;
}
write_unlock(&xfrm_policy_afinfo_lock);
return err;
}
EXPORT_SYMBOL(xfrm_policy_register_afinfo);
int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
{
int err = 0;
if (unlikely(afinfo == NULL))
return -EINVAL;
if (unlikely(afinfo->family >= NPROTO))
return -EAFNOSUPPORT;
write_lock(&xfrm_policy_afinfo_lock);
if (likely(xfrm_policy_afinfo[afinfo->family] != NULL)) {
if (unlikely(xfrm_policy_afinfo[afinfo->family] != afinfo))
err = -EINVAL;
else {
struct dst_ops *dst_ops = afinfo->dst_ops;
xfrm_policy_afinfo[afinfo->family] = NULL;
dst_ops->kmem_cachep = NULL;
dst_ops->check = NULL;
dst_ops->negative_advice = NULL;
dst_ops->link_failure = NULL;
afinfo->garbage_collect = NULL;
}
}
write_unlock(&xfrm_policy_afinfo_lock);
return err;
}
EXPORT_SYMBOL(xfrm_policy_unregister_afinfo);
static struct xfrm_policy_afinfo *xfrm_policy_get_afinfo(unsigned short family)
{
struct xfrm_policy_afinfo *afinfo;
if (unlikely(family >= NPROTO))
return NULL;
read_lock(&xfrm_policy_afinfo_lock);
afinfo = xfrm_policy_afinfo[family];
if (likely(afinfo != NULL))
read_lock(&afinfo->lock);
read_unlock(&xfrm_policy_afinfo_lock);
return afinfo;
}
static void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo)
{
if (unlikely(afinfo == NULL))
return;
read_unlock(&afinfo->lock);
}
static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
switch (event) {
case NETDEV_DOWN:
xfrm_flush_bundles();
}
return NOTIFY_DONE;
}
static struct notifier_block xfrm_dev_notifier = {
xfrm_dev_event,
NULL,
0
};
static void __init xfrm_policy_init(void)
{
xfrm_dst_cache = kmem_cache_create("xfrm_dst_cache",
sizeof(struct xfrm_dst),
0, SLAB_HWCACHE_ALIGN,
NULL, NULL);
if (!xfrm_dst_cache)
panic("XFRM: failed to allocate xfrm_dst_cache\n");
INIT_WORK(&xfrm_policy_gc_work, xfrm_policy_gc_task, NULL);
register_netdevice_notifier(&xfrm_dev_notifier);
}
void __init xfrm_init(void)
{
xfrm_state_init();
xfrm_policy_init();
xfrm_input_init();
}