skb protocol offsets are relative to the beginning of the
buffer and therefore must be updated if the buffer size is
expanded. Kernel functions do this automatically for existing
fields but obviously not for anything that we backport. This
introduces a wrapper for pskb_expand_head() to update the
inner protocol fields that we have backported.
Without this, a kernel crash can be triggered with tunnel
packets that do not have enough headroom and need to be
segmented. pskb_expand_head() is called in directly through
skb_cow_head() at the beginning of each of the tunnel transmit
routines.
Reported-by: Yinpeijun <yinpei...@huawei.com>
Signed-off-by: Jesse Gross <je...@nicira.com>
---
v2: Use existing backported skb offset APIs to avoid introducing
additional version checks.
v3: Move macro into skbuff.h to ensure that it rewrites all calls
of pskb_expand_head().
---
datapath/linux/compat/gso.h | 17 +++++++++++++++++
datapath/linux/compat/include/linux/skbuff.h | 14 +++++++++++++-
datapath/linux/compat/skbuff-openvswitch.c | 25 +++++++++++++++++++++++++
3 files changed, 55 insertions(+), 1 deletion(-)
diff --git a/datapath/linux/compat/gso.h b/datapath/linux/compat/gso.h
index 337d13a..dce4c67 100644
--- a/datapath/linux/compat/gso.h
+++ b/datapath/linux/compat/gso.h
@@ -52,6 +52,15 @@ static inline int skb_inner_network_offset(const struct
sk_buff *skb)
return skb_inner_network_header(skb) - skb->data;
}
+/* We don't actually store the transport offset on backports because
+ * we don't use it anywhere. Slightly rename this version to avoid
+ * future users from picking it up accidentially.
+ */
+static inline int ovs_skb_inner_transport_offset(const struct sk_buff *skb)
+{
+ return 0;
+}
+
static inline void skb_set_inner_network_header(const struct sk_buff *skb,
int offset)
{
@@ -62,6 +71,14 @@ static inline void skb_set_inner_network_header(const struct
sk_buff *skb,
static inline void skb_set_inner_transport_header(const struct sk_buff *skb,
int offset)
{ }
+
+#else
+
+static inline int ovs_skb_inner_transport_offset(const struct sk_buff *skb)
+{
+ return skb_inner_transport_header(skb) - skb->data;
+}
+
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)
diff --git a/datapath/linux/compat/include/linux/skbuff.h
b/datapath/linux/compat/include/linux/skbuff.h
index d147192..dc3fea8 100644
--- a/datapath/linux/compat/include/linux/skbuff.h
+++ b/datapath/linux/compat/include/linux/skbuff.h
@@ -1,10 +1,22 @@
#ifndef __LINUX_SKBUFF_WRAPPER_H
#define __LINUX_SKBUFF_WRAPPER_H 1
+#include <linux/version.h>
+#include <linux/types.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0)
+/* This should be before skbuff.h to make sure that we rewrite
+ * the calls there. */
+struct sk_buff;
+
+int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
+ gfp_t gfp_mask);
+#define pskb_expand_head rpl_pskb_expand_head
+#endif
+
#include_next <linux/skbuff.h>
#include <linux/jhash.h>
-#include <linux/version.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,9,0)
#define SKB_GSO_GRE 0
diff --git a/datapath/linux/compat/skbuff-openvswitch.c
b/datapath/linux/compat/skbuff-openvswitch.c
index 5de43b3..cd6e13f 100644
--- a/datapath/linux/compat/skbuff-openvswitch.c
+++ b/datapath/linux/compat/skbuff-openvswitch.c
@@ -3,6 +3,8 @@
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
+#include "gso.h"
+
#if !defined(HAVE_SKB_WARN_LRO) && defined(NETIF_F_LRO)
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -234,3 +236,26 @@ int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto,
u16 vlan_tci)
return 0;
}
#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0)
+int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask)
+{
+ int err;
+ unsigned int inner_mac_offset, inner_nw_offset, inner_transport_offset;
+
+ inner_mac_offset = skb_inner_mac_offset(skb);
+ inner_nw_offset = skb_inner_network_offset(skb);
+ inner_transport_offset = ovs_skb_inner_transport_offset(skb);
+
+#undef pskb_expand_head
+ err = pskb_expand_head(skb, nhead, ntail, gfp_mask);
+ if (err)
+ return err;
+
+ skb_set_inner_mac_header(skb, inner_mac_offset);
+ skb_set_inner_network_header(skb, inner_nw_offset);
+ skb_set_inner_transport_header(skb, inner_transport_offset);
+
+ return 0;
+}
+#endif
--
1.9.1
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