The XFRMA_TFCPAD attribute for XFRM state installation configures
Traffic Flow Confidentiality by padding ESP packets to a specified
length. To use RFC4303 TFC padding and overcome the 255 byte ESP
padding field limit, the XFRM_TFC_ESPV3 flag must be set.
Signed-off-by: Martin Willi <mar...@strongswan.org>
---
include/linux/xfrm.h | 7 +++++++
include/net/xfrm.h | 1 +
net/xfrm/xfrm_user.c | 16 ++++++++++++++--
3 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index b971e38..b1e5f8a 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -283,6 +283,7 @@ enum xfrm_attr_type_t {
XFRMA_KMADDRESS, /* struct xfrm_user_kmaddress */
XFRMA_ALG_AUTH_TRUNC, /* struct xfrm_algo_auth */
XFRMA_MARK, /* struct xfrm_mark */
+ XFRMA_TFC, /* struct xfrm_tfc */
__XFRMA_MAX
#define XFRMA_MAX (__XFRMA_MAX - 1)
@@ -293,6 +294,12 @@ struct xfrm_mark {
__u32 m; /* mask */
};
+struct xfrm_tfc {
+ __u16 pad;
+ __u16 flags;
+#define XFRM_TFC_ESPV3 1 /* RFC4303 TFC padding, if possible */
+};
+
enum xfrm_sadattr_type_t {
XFRMA_SAD_UNSPEC,
XFRMA_SAD_CNT,
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index bcfb6b2..03468c0 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -143,6 +143,7 @@ struct xfrm_state {
struct xfrm_id id;
struct xfrm_selector sel;
struct xfrm_mark mark;
+ struct xfrm_tfc tfc;
u32 genid;
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 8bae6b2..0b4ec02 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -148,7 +148,8 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
!attrs[XFRMA_ALG_AUTH_TRUNC]) ||
attrs[XFRMA_ALG_AEAD] ||
attrs[XFRMA_ALG_CRYPT] ||
- attrs[XFRMA_ALG_COMP])
+ attrs[XFRMA_ALG_COMP] ||
+ attrs[XFRMA_TFC])
goto out;
break;
@@ -172,7 +173,8 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
attrs[XFRMA_ALG_AEAD] ||
attrs[XFRMA_ALG_AUTH] ||
attrs[XFRMA_ALG_AUTH_TRUNC] ||
- attrs[XFRMA_ALG_CRYPT])
+ attrs[XFRMA_ALG_CRYPT] ||
+ attrs[XFRMA_TFC])
goto out;
break;
@@ -186,6 +188,7 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
attrs[XFRMA_ALG_CRYPT] ||
attrs[XFRMA_ENCAP] ||
attrs[XFRMA_SEC_CTX] ||
+ attrs[XFRMA_TFC] ||
!attrs[XFRMA_COADDR])
goto out;
break;
@@ -439,6 +442,9 @@ static struct xfrm_state *xfrm_state_construct(struct net
*net,
goto error;
}
+ if (attrs[XFRMA_TFC])
+ memcpy(&x->tfc, nla_data(attrs[XFRMA_TFC]), sizeof(x->tfc));
+
if (attrs[XFRMA_COADDR]) {
x->coaddr = kmemdup(nla_data(attrs[XFRMA_COADDR]),
sizeof(*x->coaddr), GFP_KERNEL);
@@ -688,6 +694,9 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
if (x->encap)
NLA_PUT(skb, XFRMA_ENCAP, sizeof(*x->encap), x->encap);
+ if (x->tfc.pad || x->tfc.flags)
+ NLA_PUT(skb, XFRMA_TFC, sizeof(x->tfc), &x->tfc);
+
if (xfrm_mark_put(skb, &x->mark))
goto nla_put_failure;
@@ -2122,6 +2131,7 @@ static const struct nla_policy xfrma_policy[XFRMA_MAX+1]
= {
[XFRMA_MIGRATE] = { .len = sizeof(struct xfrm_user_migrate) },
[XFRMA_KMADDRESS] = { .len = sizeof(struct xfrm_user_kmaddress) },
[XFRMA_MARK] = { .len = sizeof(struct xfrm_mark) },
+ [XFRMA_TFC] = { .len = sizeof(struct xfrm_tfc) },
};
static struct xfrm_link {
@@ -2301,6 +2311,8 @@ static inline size_t xfrm_sa_len(struct xfrm_state *x)
l += nla_total_size(sizeof(*x->calg));
if (x->encap)
l += nla_total_size(sizeof(*x->encap));
+ if (x->tfc.pad)
+ l += nla_total_size(sizeof(x->tfc));
if (x->security)
l += nla_total_size(sizeof(struct xfrm_user_sec_ctx) +
x->security->ctx_len);
--
1.7.1
--
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