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linux/net/xfrm/xfrm_replay.c
Thomas Egerer cd808fc9a6 xfrm: Fix aevent generation for each received packet 
If asynchronous events are enabled for a particular netlink socket,
the notify function is called by the advance function. The notify
function creates and dispatches a km_event if a replay timeout occurred,
or at least replay_maxdiff packets have been received since the last
asynchronous event has been sent. The function is supposed to return if
neither of the two events were detected for a state, or replay_maxdiff
is equal to zero.
Replay_maxdiff is initialized in xfrm_state_construct to the value of
the xfrm.sysctl_aevent_rseqth (2 by default), and updated if for a state
if the netlink attribute XFRMA_REPLAY_THRESH is set.
If, however, replay_maxdiff is set to zero, then all of the three notify
implementations perform a break from the switch statement instead of
checking whether a timeout occurred, and -- if not -- return.  As a
result an asynchronous event is generated for every replay update of a
state that has a zero replay_maxdiff value.
This patch modifies the notify functions such that they immediately
return if replay_maxdiff has the value zero, unless a timeout occurred.

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2013-09-25 07:32:48 +02:00

604 lines
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/*
* 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 <linux/export.h>
#include <net/xfrm.h>
u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
{
u32 seq, seq_hi, bottom;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
if (!(x->props.flags & XFRM_STATE_ESN))
return 0;
seq = ntohl(net_seq);
seq_hi = replay_esn->seq_hi;
bottom = replay_esn->seq - replay_esn->replay_window + 1;
if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
/* A. same subspace */
if (unlikely(seq < bottom))
seq_hi++;
} else {
/* B. window spans two subspaces */
if (unlikely(seq >= bottom))
seq_hi--;
}
return seq_hi;
}
static void xfrm_replay_notify(struct xfrm_state *x, int event)
{
struct km_event c;
/* 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 ||
((x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
(x->replay.oseq - x->preplay.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, &x->preplay,
sizeof(struct xfrm_replay_state)) == 0) {
x->xflags |= XFRM_TIME_DEFER;
return;
}
break;
}
memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
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 int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
{
int err = 0;
struct net *net = xs_net(x);
if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
if (unlikely(x->replay.oseq == 0)) {
x->replay.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(struct xfrm_state *x,
struct sk_buff *skb, __be32 net_seq)
{
u32 diff;
u32 seq = ntohl(net_seq);
if (!x->props.replay_window)
return 0;
if (unlikely(seq == 0))
goto err;
if (likely(seq > x->replay.seq))
return 0;
diff = x->replay.seq - seq;
if (diff >= x->props.replay_window) {
x->stats.replay_window++;
goto err;
}
if (x->replay.bitmap & (1U << diff)) {
x->stats.replay++;
goto err;
}
return 0;
err:
xfrm_audit_state_replay(x, skb, net_seq);
return -EINVAL;
}
static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
{
u32 diff;
u32 seq = ntohl(net_seq);
if (!x->props.replay_window)
return;
if (seq > x->replay.seq) {
diff = seq - x->replay.seq;
if (diff < x->props.replay_window)
x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
else
x->replay.bitmap = 1;
x->replay.seq = seq;
} else {
diff = x->replay.seq - seq;
x->replay.bitmap |= (1U << diff);
}
if (xfrm_aevent_is_on(xs_net(x)))
x->repl->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 pos;
u32 seq = ntohl(net_seq);
u32 diff = replay_esn->seq - seq;
if (!replay_esn->replay_window)
return 0;
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;
}
pos = (replay_esn->seq - 1) % replay_esn->replay_window;
if (pos >= diff)
bitnr = (pos - diff) % replay_esn->replay_window;
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;
if (!replay_esn->replay_window)
return;
pos = (replay_esn->seq - 1) % replay_esn->replay_window;
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);
}
} else {
nr = (replay_esn->replay_window - 1) >> 5;
for (i = 0; i <= nr; i++)
replay_esn->bmp[i] = 0;
}
bitnr = (pos + diff) % replay_esn->replay_window;
replay_esn->seq = seq;
} else {
diff = replay_esn->seq - seq;
if (pos >= diff)
bitnr = (pos - diff) % replay_esn->replay_window;
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)))
x->repl->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 void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
{
u32 seq_diff, oseq_diff;
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) {
if (replay_esn->seq_hi == preplay_esn->seq_hi)
seq_diff = replay_esn->seq - preplay_esn->seq;
else
seq_diff = ~preplay_esn->seq + replay_esn->seq
+ 1;
if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
oseq_diff = replay_esn->oseq
- preplay_esn->oseq;
else
oseq_diff = ~preplay_esn->oseq
+ replay_esn->oseq + 1;
if (seq_diff >= x->replay_maxdiff ||
oseq_diff >= x->replay_maxdiff)
break;
}
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 int xfrm_replay_overflow_esn(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;
XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
if (unlikely(replay_esn->oseq == 0)) {
XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
if (replay_esn->oseq_hi == 0) {
replay_esn->oseq--;
replay_esn->oseq_hi--;
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_esn(struct xfrm_state *x,
struct sk_buff *skb, __be32 net_seq)
{
unsigned int bitnr, nr;
u32 diff;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
u32 pos;
u32 seq = ntohl(net_seq);
u32 wsize = replay_esn->replay_window;
u32 top = replay_esn->seq;
u32 bottom = top - wsize + 1;
if (!wsize)
return 0;
if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
(replay_esn->seq < replay_esn->replay_window - 1)))
goto err;
diff = top - seq;
if (likely(top >= wsize - 1)) {
/* A. same subspace */
if (likely(seq > top) || seq < bottom)
return 0;
} else {
/* B. window spans two subspaces */
if (likely(seq > top && seq < bottom))
return 0;
if (seq >= bottom)
diff = ~seq + top + 1;
}
if (diff >= replay_esn->replay_window) {
x->stats.replay_window++;
goto err;
}
pos = (replay_esn->seq - 1) % replay_esn->replay_window;
if (pos >= diff)
bitnr = (pos - diff) % replay_esn->replay_window;
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 int xfrm_replay_recheck_esn(struct xfrm_state *x,
struct sk_buff *skb, __be32 net_seq)
{
if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
htonl(xfrm_replay_seqhi(x, net_seq)))) {
x->stats.replay_window++;
return -EINVAL;
}
return xfrm_replay_check_esn(x, skb, net_seq);
}
static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
{
unsigned int bitnr, nr, i;
int wrap;
u32 diff, pos, seq, seq_hi;
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
if (!replay_esn->replay_window)
return;
seq = ntohl(net_seq);
pos = (replay_esn->seq - 1) % replay_esn->replay_window;
seq_hi = xfrm_replay_seqhi(x, net_seq);
wrap = seq_hi - replay_esn->seq_hi;
if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
if (likely(!wrap))
diff = seq - replay_esn->seq;
else
diff = ~replay_esn->seq + seq + 1;
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);
}
} else {
nr = (replay_esn->replay_window - 1) >> 5;
for (i = 0; i <= nr; i++)
replay_esn->bmp[i] = 0;
}
bitnr = (pos + diff) % replay_esn->replay_window;
replay_esn->seq = seq;
if (unlikely(wrap > 0))
replay_esn->seq_hi++;
} else {
diff = replay_esn->seq - seq;
if (pos >= diff)
bitnr = (pos - diff) % replay_esn->replay_window;
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)))
x->repl->notify(x, XFRM_REPLAY_UPDATE);
}
static struct xfrm_replay xfrm_replay_legacy = {
.advance = xfrm_replay_advance,
.check = xfrm_replay_check,
.recheck = xfrm_replay_check,
.notify = xfrm_replay_notify,
.overflow = xfrm_replay_overflow,
};
static struct xfrm_replay xfrm_replay_bmp = {
.advance = xfrm_replay_advance_bmp,
.check = xfrm_replay_check_bmp,
.recheck = xfrm_replay_check_bmp,
.notify = xfrm_replay_notify_bmp,
.overflow = xfrm_replay_overflow_bmp,
};
static struct xfrm_replay xfrm_replay_esn = {
.advance = xfrm_replay_advance_esn,
.check = xfrm_replay_check_esn,
.recheck = xfrm_replay_recheck_esn,
.notify = xfrm_replay_notify_esn,
.overflow = xfrm_replay_overflow_esn,
};
int xfrm_init_replay(struct xfrm_state *x)
{
struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
if (replay_esn) {
if (replay_esn->replay_window >
replay_esn->bmp_len * sizeof(__u32) * 8)
return -EINVAL;
if (x->props.flags & XFRM_STATE_ESN) {
if (replay_esn->replay_window == 0)
return -EINVAL;
x->repl = &xfrm_replay_esn;
} else
x->repl = &xfrm_replay_bmp;
} else
x->repl = &xfrm_replay_legacy;
return 0;
}
EXPORT_SYMBOL(xfrm_init_replay);
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