Call get_unaligned_be32 when we access 32-bit fields in
__skb_flow_dissect. At the beginning check for unlikely case of
1-byte aligned packet.
Note that flow_dissector may be asked to parse packet unaligned
fields in two instances:
1) Packet from a driver which is aligned to Ethernet header
(2-byte alignment)
2) Parsing inner headers of a received GRE-TEB packet
Testing: Ran super_netperf tests did not see a regression. This was on
x86 which does not have problems with unaligned data.
Signed-off-by: Tom Herbert <t...@herbertland.com>
---
net/core/flow_dissector.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index d79699c..1c64a1a 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -95,7 +95,7 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int
thoff, u8 ip_proto,
ports = __skb_header_pointer(skb, thoff + poff,
sizeof(_ports), data, hlen,
&_ports);
if (ports)
- return *ports;
+ return get_unaligned_be32(ports);
}
return 0;
@@ -116,6 +116,10 @@ EXPORT_SYMBOL(__skb_flow_get_ports);
* by flow_dissector from either the skbuff or a raw buffer specified by the
* rest parameters.
*
+ * This function does not assume 4-byte alignment, but it does assume 2-byte
+ * alignment (false is returned for 1-byte alignment). get_unaligned_be32
+ * is called to get thirty-two values out of the packet.
+ *
* Caller must take care of zeroing target container memory.
*/
bool __skb_flow_dissect(const struct sk_buff *skb,
@@ -140,6 +144,11 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
hlen = skb_headlen(skb);
}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ if (WARN_ON(((u64)data & 0x1)))
+ return false;
+#endif
+
/* It is ensured by skb_flow_dissector_init() that control key will
* be always present.
*/
@@ -230,7 +239,7 @@ ipv6:
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
}
- flow_label = ip6_flowlabel(iph);
+ flow_label = get_unaligned_be32(iph) & IPV6_FLOWLABEL_MASK;
if (flow_label) {
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
@@ -303,7 +312,7 @@ ipv6:
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_TIPC_ADDRS,
target_container);
- key_addrs->tipcaddrs.srcnode = hdr->srcnode;
+ key_addrs->tipcaddrs.srcnode =
get_unaligned_be32(&hdr->srcnode);
key_control->addr_type = FLOW_DISSECTOR_KEY_TIPC_ADDRS;
}
goto out_good;
@@ -325,7 +334,7 @@ mpls:
key_keyid =
skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_MPLS_ENTROPY,
target_container);
- key_keyid->keyid = hdr[1].entry &
+ key_keyid->keyid =
get_unaligned_be32(&hdr[1].entry) &
htonl(MPLS_LS_LABEL_MASK);
}
@@ -379,7 +388,7 @@ ip_proto_again:
key_keyid =
skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_GRE_KEYID,
target_container);
- key_keyid->keyid = *keyid;
+ key_keyid->keyid = get_unaligned_be32(keyid);
}
nhoff += 4;
}
--
2.4.6
