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xfrm: introduce oseq-may-wrap flag

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RFC 4303 in section 3.3.3 suggests to disable anti-replay for manually
distributed ICVs in which case the sender does not need to monitor or
reset the counter. However, the sender still increments the counter and
when it reaches the maximum value, the counter rolls over back to zero.

This patch introduces new extra_flag XFRM_SA_XFLAG_OSEQ_MAY_WRAP which
allows sequence number to cycle in outbound packets if set. This flag is
used only in legacy and bmp code, because esn should not be negotiated
if anti-replay is disabled (see note in 3.3.3 section).

Signed-off-by: Petr Vaněk <pv@excello.cz>
Acked-by: Christophe Gouault <christophe.gouault@6wind.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Petr Vaněk 2020-05-30 14:39:12 +02:00 committed by Steffen Klassert
parent 8af7b4525a
commit 428d2459cc
2 changed files with 9 additions and 4 deletions
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1
include/uapi/linux/xfrm.h
View File

@ -387,6 +387,7 @@ struct xfrm_usersa_info {
};
#define XFRM_SA_XFLAG_DONT_ENCAP_DSCP 1
#define XFRM_SA_XFLAG_OSEQ_MAY_WRAP 2
struct xfrm_usersa_id {
xfrm_address_t daddr;

12
net/xfrm/xfrm_replay.c
View File

@ -89,7 +89,8 @@ static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
XFRM_SKB_CB(skb)->seq.output.hi = 0;
if (unlikely(x->replay.oseq == 0)) {
if (unlikely(x->replay.oseq == 0) &&
!(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
x->replay.oseq--;
xfrm_audit_state_replay_overflow(x, skb);
err = -EOVERFLOW;
@ -168,7 +169,8 @@ static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
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 = 0;
if (unlikely(replay_esn->oseq == 0)) {
if (unlikely(replay_esn->oseq == 0) &&
!(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
replay_esn->oseq--;
xfrm_audit_state_replay_overflow(x, skb);
err = -EOVERFLOW;
@ -572,7 +574,8 @@ static int xfrm_replay_overflow_offload(struct xfrm_state *x, struct sk_buff *sk
XFRM_SKB_CB(skb)->seq.output.hi = 0;
xo->seq.hi = 0;
if (unlikely(oseq < x->replay.oseq)) {
if (unlikely(oseq < x->replay.oseq) &&
!(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
xfrm_audit_state_replay_overflow(x, skb);
err = -EOVERFLOW;
@ -611,7 +614,8 @@ static int xfrm_replay_overflow_offload_bmp(struct xfrm_state *x, struct sk_buff
XFRM_SKB_CB(skb)->seq.output.hi = 0;
xo->seq.hi = 0;
if (unlikely(oseq < replay_esn->oseq)) {
if (unlikely(oseq < replay_esn->oseq) &&
!(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
xfrm_audit_state_replay_overflow(x, skb);
err = -EOVERFLOW;