xfrm: Add support for network devices capable of removing the ESP trailer

In conjunction with crypto offload [1], removing the ESP trailer by
hardware can potentially improve the performance by avoiding (1) a
cache miss incurred by reading the nexthdr field and (2) the necessity
to calculate the csum value of the trailer in order to keep skb->csum
valid.

This patch introduces the changes to the xfrm stack and merely serves
as an infrastructure. Subsequent patch to mlx5 driver will put this to
a good use.

[1] https://www.mail-archive.com/netdev@vger.kernel.org/msg175733.html

Signed-off-by: Yossi Kuperman <yossiku@mellanox.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 9c7b70c..f002a2c 100644 (file)
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1019,6 +1019,7 @@ struct xfrm_offload {
 #define        CRYPTO_FALLBACK         8
 #define        XFRM_GSO_SEGMENT        16
 #define        XFRM_GRO                32
+#define        XFRM_ESP_NO_TRAILER     64
 
        __u32                   status;
 #define CRYPTO_SUCCESS                         1

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 741acd7..3190005 100644 (file)
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -499,19 +499,59 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
        return esp_output_tail(x, skb, &esp);
 }
 
+static inline int esp_remove_trailer(struct sk_buff *skb)
+{
+       struct xfrm_state *x = xfrm_input_state(skb);
+       struct xfrm_offload *xo = xfrm_offload(skb);
+       struct crypto_aead *aead = x->data;
+       int alen, hlen, elen;
+       int padlen, trimlen;
+       __wsum csumdiff;
+       u8 nexthdr[2];
+       int ret;
+
+       alen = crypto_aead_authsize(aead);
+       hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
+       elen = skb->len - hlen;
+
+       if (xo && (xo->flags & XFRM_ESP_NO_TRAILER)) {
+               ret = xo->proto;
+               goto out;
+       }
+
+       if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
+               BUG();
+
+       ret = -EINVAL;
+       padlen = nexthdr[0];
+       if (padlen + 2 + alen >= elen) {
+               net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
+                                   padlen + 2, elen - alen);
+               goto out;
+       }
+
+       trimlen = alen + padlen + 2;
+       if (skb->ip_summed == CHECKSUM_COMPLETE) {
+               csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
+               skb->csum = csum_block_sub(skb->csum, csumdiff,
+                                          skb->len - trimlen);
+       }
+       pskb_trim(skb, skb->len - trimlen);
+
+       ret = nexthdr[1];
+
+out:
+       return ret;
+}
+
 int esp_input_done2(struct sk_buff *skb, int err)
 {
        const struct iphdr *iph;
        struct xfrm_state *x = xfrm_input_state(skb);
        struct xfrm_offload *xo = xfrm_offload(skb);
        struct crypto_aead *aead = x->data;
-       int alen = crypto_aead_authsize(aead);
        int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
-       int elen = skb->len - hlen;
        int ihl;
-       u8 nexthdr[2];
-       int padlen, trimlen;
-       __wsum csumdiff;
 
        if (!xo || (xo && !(xo->flags & CRYPTO_DONE)))
                kfree(ESP_SKB_CB(skb)->tmp);
@@ -519,16 +559,10 @@ int esp_input_done2(struct sk_buff *skb, int err)
        if (unlikely(err))
                goto out;
 
-       if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
-               BUG();
-
-       err = -EINVAL;
-       padlen = nexthdr[0];
-       if (padlen + 2 + alen >= elen)
+       err = esp_remove_trailer(skb);
+       if (unlikely(err < 0))
                goto out;
 
-       /* ... check padding bits here. Silly. :-) */
-
        iph = ip_hdr(skb);
        ihl = iph->ihl * 4;
 
@@ -569,22 +603,12 @@ int esp_input_done2(struct sk_buff *skb, int err)
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
        }
 
-       trimlen = alen + padlen + 2;
-       if (skb->ip_summed == CHECKSUM_COMPLETE) {
-               csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
-               skb->csum = csum_block_sub(skb->csum, csumdiff,
-                                          skb->len - trimlen);
-       }
-       pskb_trim(skb, skb->len - trimlen);
-
        skb_pull_rcsum(skb, hlen);
        if (x->props.mode == XFRM_MODE_TUNNEL)
                skb_reset_transport_header(skb);
        else
                skb_set_transport_header(skb, -ihl);
 
-       err = nexthdr[1];
-
        /* RFC4303: Drop dummy packets without any error */
        if (err == IPPROTO_NONE)
                err = -EINVAL;

diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 74bde20..7fb41b0 100644 (file)
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -461,29 +461,30 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
        return esp6_output_tail(x, skb, &esp);
 }
 
-int esp6_input_done2(struct sk_buff *skb, int err)
+static inline int esp_remove_trailer(struct sk_buff *skb)
 {
        struct xfrm_state *x = xfrm_input_state(skb);
        struct xfrm_offload *xo = xfrm_offload(skb);
        struct crypto_aead *aead = x->data;
-       int alen = crypto_aead_authsize(aead);
-       int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
-       int elen = skb->len - hlen;
-       int hdr_len = skb_network_header_len(skb);
+       int alen, hlen, elen;
        int padlen, trimlen;
        __wsum csumdiff;
        u8 nexthdr[2];
+       int ret;
 
-       if (!xo || (xo && !(xo->flags & CRYPTO_DONE)))
-               kfree(ESP_SKB_CB(skb)->tmp);
+       alen = crypto_aead_authsize(aead);
+       hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
+       elen = skb->len - hlen;
 
-       if (unlikely(err))
+       if (xo && (xo->flags & XFRM_ESP_NO_TRAILER)) {
+               ret = xo->proto;
                goto out;
+       }
 
        if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
                BUG();
 
-       err = -EINVAL;
+       ret = -EINVAL;
        padlen = nexthdr[0];
        if (padlen + 2 + alen >= elen) {
                net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
@@ -491,26 +492,46 @@ int esp6_input_done2(struct sk_buff *skb, int err)
                goto out;
        }
 
-       /* ... check padding bits here. Silly. :-) */
-
        trimlen = alen + padlen + 2;
        if (skb->ip_summed == CHECKSUM_COMPLETE) {
-               skb_postpull_rcsum(skb, skb_network_header(skb),
-                                  skb_network_header_len(skb));
                csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
                skb->csum = csum_block_sub(skb->csum, csumdiff,
                                           skb->len - trimlen);
        }
        pskb_trim(skb, skb->len - trimlen);
 
+       ret = nexthdr[1];
+
+out:
+       return ret;
+}
+
+int esp6_input_done2(struct sk_buff *skb, int err)
+{
+       struct xfrm_state *x = xfrm_input_state(skb);
+       struct xfrm_offload *xo = xfrm_offload(skb);
+       struct crypto_aead *aead = x->data;
+       int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
+       int hdr_len = skb_network_header_len(skb);
+
+       if (!xo || (xo && !(xo->flags & CRYPTO_DONE)))
+               kfree(ESP_SKB_CB(skb)->tmp);
+
+       if (unlikely(err))
+               goto out;
+
+       err = esp_remove_trailer(skb);
+       if (unlikely(err < 0))
+               goto out;
+
+       skb_postpull_rcsum(skb, skb_network_header(skb),
+                          skb_network_header_len(skb));
        skb_pull_rcsum(skb, hlen);
        if (x->props.mode == XFRM_MODE_TUNNEL)
                skb_reset_transport_header(skb);
        else
                skb_set_transport_header(skb, -hdr_len);
 
-       err = nexthdr[1];
-
        /* RFC4303: Drop dummy packets without any error */
        if (err == IPPROTO_NONE)
                err = -EINVAL;

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index f07eec5..2515cd2 100644 (file)
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -247,6 +247,11 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
                                        goto drop;
                                }
 
+                               if (xo->status & CRYPTO_INVALID_PROTOCOL) {
+                                       XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEPROTOERROR);
+                                       goto drop;
+                               }
+
                                XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
                                goto drop;
                        }