Commit 97e15c3a authored by Steffen Klassert's avatar Steffen Klassert Committed by David S. Miller

xfrm: Support anti-replay window size bigger than 32 packets

As it is, the anti-replay bitmap in struct xfrm_replay_state can
only accomodate 32 packets. Even though it is possible to configure
anti-replay window sizes up to 255 packets from userspace. So we
reject any packet with a sequence number within the configured window
but outside the bitmap. With this patch, we represent the anti-replay
window as a bitmap of variable length that can be accessed via the
new struct xfrm_replay_state_esn. Thus, we have no limit on the
window size anymore. To use the new anti-replay window implementantion,
new userspace tools are required. We leave the old implementation
untouched to stay in sync with old userspace tools.
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
Acked-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9fdc4883
/*
* xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c.
*
* Copyright (C) 2010 secunet Security Networks AG
* Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 <net/xfrm.h>
......@@ -125,6 +141,178 @@ static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
}
static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
{
int err = 0;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
struct net *net = xs_net(x);
if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
if (unlikely(replay_esn->oseq == 0)) {
replay_esn->oseq--;
xfrm_audit_state_replay_overflow(x, skb);
err = -EOVERFLOW;
return err;
}
if (xfrm_aevent_is_on(net))
x->repl->notify(x, XFRM_REPLAY_UPDATE);
}
return err;
}
static int xfrm_replay_check_bmp(struct xfrm_state *x,
struct sk_buff *skb, __be32 net_seq)
{
unsigned int bitnr, nr;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
u32 seq = ntohl(net_seq);
u32 diff = replay_esn->seq - seq;
u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
if (unlikely(seq == 0))
goto err;
if (likely(seq > replay_esn->seq))
return 0;
if (diff >= replay_esn->replay_window) {
x->stats.replay_window++;
goto err;
}
if (pos >= diff) {
bitnr = (pos - diff) % replay_esn->replay_window;
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
if (replay_esn->bmp[nr] & (1U << bitnr))
goto err_replay;
} else {
bitnr = replay_esn->replay_window - (diff - pos);
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
if (replay_esn->bmp[nr] & (1U << bitnr))
goto err_replay;
}
return 0;
err_replay:
x->stats.replay++;
err:
xfrm_audit_state_replay(x, skb, net_seq);
return -EINVAL;
}
static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
{
unsigned int bitnr, nr, i;
u32 diff;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
u32 seq = ntohl(net_seq);
u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
if (!replay_esn->replay_window)
return;
if (seq > replay_esn->seq) {
diff = seq - replay_esn->seq;
if (diff < replay_esn->replay_window) {
for (i = 1; i < diff; i++) {
bitnr = (pos + i) % replay_esn->replay_window;
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
replay_esn->bmp[nr] &= ~(1U << bitnr);
}
bitnr = (pos + diff) % replay_esn->replay_window;
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
replay_esn->bmp[nr] |= (1U << bitnr);
} else {
nr = replay_esn->replay_window >> 5;
for (i = 0; i <= nr; i++)
replay_esn->bmp[i] = 0;
bitnr = (pos + diff) % replay_esn->replay_window;
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
replay_esn->bmp[nr] |= (1U << bitnr);
}
replay_esn->seq = seq;
} else {
diff = replay_esn->seq - seq;
if (pos >= diff) {
bitnr = (pos - diff) % replay_esn->replay_window;
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
replay_esn->bmp[nr] |= (1U << bitnr);
} else {
bitnr = replay_esn->replay_window - (diff - pos);
nr = bitnr >> 5;
bitnr = bitnr & 0x1F;
replay_esn->bmp[nr] |= (1U << bitnr);
}
}
if (xfrm_aevent_is_on(xs_net(x)))
xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
}
static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
{
struct km_event c;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
/* we send notify messages in case
* 1. we updated on of the sequence numbers, and the seqno difference
* is at least x->replay_maxdiff, in this case we also update the
* timeout of our timer function
* 2. if x->replay_maxage has elapsed since last update,
* and there were changes
*
* The state structure must be locked!
*/
switch (event) {
case XFRM_REPLAY_UPDATE:
if (x->replay_maxdiff &&
(replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
(replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
if (x->xflags & XFRM_TIME_DEFER)
event = XFRM_REPLAY_TIMEOUT;
else
return;
}
break;
case XFRM_REPLAY_TIMEOUT:
if (memcmp(x->replay_esn, x->preplay_esn,
xfrm_replay_state_esn_len(replay_esn)) == 0) {
x->xflags |= XFRM_TIME_DEFER;
return;
}
break;
}
memcpy(x->preplay_esn, x->replay_esn,
xfrm_replay_state_esn_len(replay_esn));
c.event = XFRM_MSG_NEWAE;
c.data.aevent = event;
km_state_notify(x, &c);
if (x->replay_maxage &&
!mod_timer(&x->rtimer, jiffies + x->replay_maxage))
x->xflags &= ~XFRM_TIME_DEFER;
}
static struct xfrm_replay xfrm_replay_legacy = {
.advance = xfrm_replay_advance,
.check = xfrm_replay_check,
......@@ -132,9 +320,26 @@ static struct xfrm_replay xfrm_replay_legacy = {
.overflow = xfrm_replay_overflow,
};
static struct xfrm_replay xfrm_replay_bmp = {
.advance = xfrm_replay_advance_bmp,
.check = xfrm_replay_check_bmp,
.notify = xfrm_replay_notify_bmp,
.overflow = xfrm_replay_overflow_bmp,
};
int xfrm_init_replay(struct xfrm_state *x)
{
x->repl = &xfrm_replay_legacy;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
if (replay_esn) {
if (replay_esn->replay_window >
replay_esn->bmp_len * sizeof(__u32))
return -EINVAL;
x->repl = &xfrm_replay_bmp;
} else
x->repl = &xfrm_replay_legacy;
return 0;
}
......
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