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Date: Wed, 8 Jan 2014 13:58:29 +0000
From: Paul Durrant <paul.durrant@...rix.com>
To: <netdev@...r.kernel.org>, <xen-devel@...ts.xen.org>
CC: Paul Durrant <paul.durrant@...rix.com>,
David Miller <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Veaceslav Falico <vfalico@...hat.com>,
Alexander Duyck <alexander.h.duyck@...el.com>,
Nicolas Dichtel <nicolas.dichtel@...nd.com>
Subject: [PATCH net-next 1/3] net: add skb_checksum_setup
This patch adds a function to set up the partial checksum offset for IP
packets (and optionally re-calculate the pseudo-header checksum) into the
core network code.
The implementation was previously private and duplicated between xen-netback
and xen-netfront, however it is not xen-specific and is potentially useful
to any network driver.
Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
Cc: David Miller <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Veaceslav Falico <vfalico@...hat.com>
Cc: Alexander Duyck <alexander.h.duyck@...el.com>
Cc: Nicolas Dichtel <nicolas.dichtel@...nd.com>
---
include/linux/netdevice.h | 1 +
net/core/dev.c | 271 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 272 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a2a70cc..15b1003 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2940,6 +2940,7 @@ void netdev_upper_dev_unlink(struct net_device *dev,
void *netdev_lower_dev_get_private(struct net_device *dev,
struct net_device *lower_dev);
int skb_checksum_help(struct sk_buff *skb);
+int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
netdev_features_t features, bool tx_path);
struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index ce01847..cf9fc30 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -101,6 +101,7 @@
#include <net/dst.h>
#include <net/pkt_sched.h>
#include <net/checksum.h>
+#include <net/ip6_checksum.h>
#include <net/xfrm.h>
#include <linux/highmem.h>
#include <linux/init.h>
@@ -2281,6 +2282,276 @@ out:
}
EXPORT_SYMBOL(skb_checksum_help);
+static inline int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
+ unsigned int max)
+{
+ if (skb_headlen(skb) >= len)
+ return 0;
+
+ /* If we need to pullup then pullup to the max, so we
+ * won't need to do it again.
+ */
+ if (max > skb->len)
+ max = skb->len;
+
+ if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
+ return -ENOMEM;
+
+ if (skb_headlen(skb) < len)
+ return -EPROTO;
+
+ return 0;
+}
+
+/* This value should be large enough to cover a tagged ethernet header plus
+ * maximally sized IP and TCP or UDP headers.
+ */
+#define MAX_IP_HDR_LEN 128
+
+static int skb_checksum_setup_ip(struct sk_buff *skb, bool recalculate)
+{
+ unsigned int off;
+ bool fragment;
+ int err;
+
+ fragment = false;
+
+ err = skb_maybe_pull_tail(skb,
+ sizeof(struct iphdr),
+ MAX_IP_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
+ fragment = true;
+
+ off = ip_hdrlen(skb);
+
+ err = -EPROTO;
+
+ if (fragment)
+ goto out;
+
+ switch (ip_hdr(skb)->protocol) {
+ case IPPROTO_TCP:
+ err = skb_maybe_pull_tail(skb,
+ off + sizeof(struct tcphdr),
+ MAX_IP_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ if (!skb_partial_csum_set(skb, off,
+ offsetof(struct tcphdr, check))) {
+ err = -EPROTO;
+ goto out;
+ }
+
+ if (recalculate)
+ tcp_hdr(skb)->check =
+ ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr,
+ skb->len - off,
+ IPPROTO_TCP, 0);
+ break;
+ case IPPROTO_UDP:
+ err = skb_maybe_pull_tail(skb,
+ off + sizeof(struct udphdr),
+ MAX_IP_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ if (!skb_partial_csum_set(skb, off,
+ offsetof(struct udphdr, check))) {
+ err = -EPROTO;
+ goto out;
+ }
+
+ if (recalculate)
+ udp_hdr(skb)->check =
+ ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr,
+ skb->len - off,
+ IPPROTO_UDP, 0);
+ break;
+ default:
+ goto out;
+ }
+
+ err = 0;
+
+out:
+ return err;
+}
+
+/* This value should be large enough to cover a tagged ethernet header plus
+ * an IPv6 header, all options, and a maximal TCP or UDP header.
+ */
+#define MAX_IPV6_HDR_LEN 256
+
+#define OPT_HDR(type, skb, off) \
+ (type *)(skb_network_header(skb) + (off))
+
+static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
+{
+ int err;
+ u8 nexthdr;
+ unsigned int off;
+ unsigned int len;
+ bool fragment;
+ bool done;
+
+ fragment = false;
+ done = false;
+
+ off = sizeof(struct ipv6hdr);
+
+ err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ nexthdr = ipv6_hdr(skb)->nexthdr;
+
+ len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+ while (off <= len && !done) {
+ switch (nexthdr) {
+ case IPPROTO_DSTOPTS:
+ case IPPROTO_HOPOPTS:
+ case IPPROTO_ROUTING: {
+ struct ipv6_opt_hdr *hp;
+
+ err = skb_maybe_pull_tail(skb,
+ off +
+ sizeof(struct ipv6_opt_hdr),
+ MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
+ nexthdr = hp->nexthdr;
+ off += ipv6_optlen(hp);
+ break;
+ }
+ case IPPROTO_AH: {
+ struct ip_auth_hdr *hp;
+
+ err = skb_maybe_pull_tail(skb,
+ off +
+ sizeof(struct ip_auth_hdr),
+ MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ hp = OPT_HDR(struct ip_auth_hdr, skb, off);
+ nexthdr = hp->nexthdr;
+ off += ipv6_authlen(hp);
+ break;
+ }
+ case IPPROTO_FRAGMENT: {
+ struct frag_hdr *hp;
+
+ err = skb_maybe_pull_tail(skb,
+ off +
+ sizeof(struct frag_hdr),
+ MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ hp = OPT_HDR(struct frag_hdr, skb, off);
+
+ if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
+ fragment = true;
+
+ nexthdr = hp->nexthdr;
+ off += sizeof(struct frag_hdr);
+ break;
+ }
+ default:
+ done = true;
+ break;
+ }
+ }
+
+ err = -EPROTO;
+
+ if (!done || fragment)
+ goto out;
+
+ switch (nexthdr) {
+ case IPPROTO_TCP:
+ err = skb_maybe_pull_tail(skb,
+ off + sizeof(struct tcphdr),
+ MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ if (!skb_partial_csum_set(skb, off,
+ offsetof(struct tcphdr, check))) {
+ err = -EPROTO;
+ goto out;
+ }
+
+ if (recalculate)
+ tcp_hdr(skb)->check =
+ ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+ &ipv6_hdr(skb)->daddr,
+ skb->len - off,
+ IPPROTO_TCP, 0);
+ break;
+ case IPPROTO_UDP:
+ err = skb_maybe_pull_tail(skb,
+ off + sizeof(struct udphdr),
+ MAX_IPV6_HDR_LEN);
+ if (err < 0)
+ goto out;
+
+ if (!skb_partial_csum_set(skb, off,
+ offsetof(struct udphdr, check))) {
+ err = -EPROTO;
+ goto out;
+ }
+
+ if (recalculate)
+ udp_hdr(skb)->check =
+ ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+ &ipv6_hdr(skb)->daddr,
+ skb->len - off,
+ IPPROTO_UDP, 0);
+ break;
+ default:
+ goto out;
+ }
+
+ err = 0;
+
+out:
+ return err;
+}
+
+/* Set up partial checksum offset and optionally recalculate pseudo header
+ * checksum.
+ */
+int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
+{
+ int err;
+
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ err = skb_checksum_setup_ip(skb, recalculate);
+ break;
+
+ case htons(ETH_P_IPV6):
+ err = skb_checksum_setup_ipv6(skb, recalculate);
+ break;
+
+ default:
+ err = -EPROTO;
+ break;
+ }
+
+ return err;
+}
+EXPORT_SYMBOL(skb_checksum_setup);
+
__be16 skb_network_protocol(struct sk_buff *skb)
{
__be16 type = skb->protocol;
--
1.7.10.4
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