xfrm: Add Traffic Flow Confidentiality padding XFRM attribute

The XFRMA_TFCPAD attribute for XFRM state installation configures
Traffic Flow Confidentiality by padding ESP packets to a specified
length.

Signed-off-by: Martin Willi <martin@strongswan.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 19 insertions, 2 deletions

diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index b971e3848493..930fdd2de79c 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_TFCPAD,           /* __u32 */
         __XFRMA_MAX
 
 #define XFRMA_MAX (__XFRMA_MAX - 1)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 7fa5b005893e..b9f385da758e 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;
+        u32                     tfcpad;
 
         u32                     genid;
 
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 8bae6b22c846..8eb889510916 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_TFCPAD])
                         goto out;
                 break;
 
@@ -165,6 +166,9 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
                      attrs[XFRMA_ALG_CRYPT]) &&
                     attrs[XFRMA_ALG_AEAD])
                         goto out;
+                if (attrs[XFRMA_TFCPAD] &&
+                    p->mode != XFRM_MODE_TUNNEL)
+                        goto out;
                 break;
 
         case IPPROTO_COMP:
@@ -172,7 +176,8 @@ 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_TFCPAD])
                         goto out;
                 break;
 
@@ -186,6 +191,7 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
                     attrs[XFRMA_ALG_CRYPT]      ||
                     attrs[XFRMA_ENCAP]          ||
                     attrs[XFRMA_SEC_CTX]        ||
+                    attrs[XFRMA_TFCPAD]         ||
                     !attrs[XFRMA_COADDR])
                         goto out;
                 break;
@@ -439,6 +445,9 @@ static struct xfrm_state *xfrm_state_construct(struct net *net,
                         goto error;
         }
 
+        if (attrs[XFRMA_TFCPAD])
+                x->tfcpad = nla_get_u32(attrs[XFRMA_TFCPAD]);
+
         if (attrs[XFRMA_COADDR]) {
                 x->coaddr = kmemdup(nla_data(attrs[XFRMA_COADDR]),
                                     sizeof(*x->coaddr), GFP_KERNEL);
@@ -688,6 +697,9 @@ 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->tfcpad)
+                NLA_PUT_U32(skb, XFRMA_TFCPAD, x->tfcpad);
+
         if (xfrm_mark_put(skb, &x->mark))
                 goto nla_put_failure;
 
@@ -2122,6 +2134,7 @@ 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_TFCPAD]          = { .type = NLA_U32 },
 };
 
 static struct xfrm_link {
@@ -2301,6 +2314,8 @@ 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->tfcpad)
+                l += nla_total_size(sizeof(x->tfcpad));
         if (x->security)
                 l += nla_total_size(sizeof(struct xfrm_user_sec_ctx) +
                                     x->security->ctx_len);