[PATCH net-next v6] net: openvswitch: IPv6: Add IPv6 extension header support

Toms Atteka
2021-09-28T19:47:36Z

This change adds a new OpenFlow field OFPXMT_OFB_IPV6_EXTHDR and
packets can be filtered using ipv6_ext flag.

Signed-off-by: Toms Atteka <cpp.code.lv@gmail.com>
---
include/uapi/linux/openvswitch.h | 12 +++
net/openvswitch/flow.c | 140 +++++++++++++++++++++++++++++++
net/openvswitch/flow.h | 14 ++++
net/openvswitch/flow_netlink.c | 24 +++++-
4 files changed, 189 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index a87b44cd5590..dc6eb5f6399f 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -346,6 +346,13 @@ enum ovs_key_attr {
#ifdef __KERNEL__
OVS_KEY_ATTR_TUNNEL_INFO, /* struct ip_tunnel_info */
#endif
+
+#ifndef __KERNEL__
+ PADDING, /* Padding so kernel and non kernel field count would match */
+#endif
+
+ OVS_KEY_ATTR_IPV6_EXTHDRS, /* struct ovs_key_ipv6_exthdr */
+
__OVS_KEY_ATTR_MAX
};

@@ -421,6 +428,11 @@ struct ovs_key_ipv6 {
__u8 ipv6_frag; /* One of OVS_FRAG_TYPE_*. */
};

+/* separate structure to support backward compatibility with older user space */
+struct ovs_key_ipv6_exthdrs {
+ __u16 hdrs;
+};
+
struct ovs_key_tcp {
__be16 tcp_src;
__be16 tcp_dst;
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 9d375e74b607..28acb40437ca 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -239,6 +239,144 @@ static bool icmphdr_ok(struct sk_buff *skb)
sizeof(struct icmphdr));
}

+/**
+ * get_ipv6_ext_hdrs() - Parses packet and sets IPv6 extension header flags.
+ *
+ * @skb: buffer where extension header data starts in packet
+ * @nh: ipv6 header
+ * @ext_hdrs: flags are stored here
+ *
+ * OFPIEH12_UNREP is set if more than one of a given IPv6 extension header
+ * is unexpectedly encountered. (Two destination options headers may be
+ * expected and would not cause this bit to be set.)
+ *
+ * OFPIEH12_UNSEQ is set if IPv6 extension headers were not in the order
+ * preferred (but not required) by RFC 2460:
+ *
+ * When more than one extension header is used in the same packet, it is
+ * recommended that those headers appear in the following order:
+ * IPv6 header
+ * Hop-by-Hop Options header
+ * Destination Options header
+ * Routing header
+ * Fragment header
+ * Authentication header
+ * Encapsulating Security Payload header
+ * Destination Options header
+ * upper-layer header
+ */
+static void get_ipv6_ext_hdrs(struct sk_buff *skb, struct ipv6hdr *nh,
+ u16 *ext_hdrs)
+{
+ u8 next_type = nh->nexthdr;
+ unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
+ int dest_options_header_count = 0;
+
+ *ext_hdrs = 0;
+
+ while (ipv6_ext_hdr(next_type)) {
+ struct ipv6_opt_hdr _hdr, *hp;
+
+ switch (next_type) {
+ case IPPROTO_NONE:
+ *ext_hdrs |= OFPIEH12_NONEXT;
+ /* stop parsing */
+ return;
+
+ case IPPROTO_ESP:
+ if (*ext_hdrs & OFPIEH12_ESP)
+ *ext_hdrs |= OFPIEH12_UNREP;
+ if ((*ext_hdrs & ~(OFPIEH12_HOP | OFPIEH12_DEST |
+ OFPIEH12_ROUTER | IPPROTO_FRAGMENT |
+ OFPIEH12_AUTH | OFPIEH12_UNREP)) ||
+ dest_options_header_count >= 2) {
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ }
+ *ext_hdrs |= OFPIEH12_ESP;
+ break;
+
+ case IPPROTO_AH:
+ if (*ext_hdrs & OFPIEH12_AUTH)
+ *ext_hdrs |= OFPIEH12_UNREP;
+ if ((*ext_hdrs &
+ ~(OFPIEH12_HOP | OFPIEH12_DEST | OFPIEH12_ROUTER |
+ IPPROTO_FRAGMENT | OFPIEH12_UNREP)) ||
+ dest_options_header_count >= 2) {
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ }
+ *ext_hdrs |= OFPIEH12_AUTH;
+ break;
+
+ case IPPROTO_DSTOPTS:
+ if (dest_options_header_count == 0) {
+ if (*ext_hdrs &
+ ~(OFPIEH12_HOP | OFPIEH12_UNREP))
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ *ext_hdrs |= OFPIEH12_DEST;
+ } else if (dest_options_header_count == 1) {
+ if (*ext_hdrs &
+ ~(OFPIEH12_HOP | OFPIEH12_DEST |
+ OFPIEH12_ROUTER | OFPIEH12_FRAG |
+ OFPIEH12_AUTH | OFPIEH12_ESP |
+ OFPIEH12_UNREP)) {
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ }
+ } else {
+ *ext_hdrs |= OFPIEH12_UNREP;
+ }
+ dest_options_header_count++;
+ break;
+
+ case IPPROTO_FRAGMENT:
+ if (*ext_hdrs & OFPIEH12_FRAG)
+ *ext_hdrs |= OFPIEH12_UNREP;
+ if ((*ext_hdrs & ~(OFPIEH12_HOP |
+ OFPIEH12_DEST |
+ OFPIEH12_ROUTER |
+ OFPIEH12_UNREP)) ||
+ dest_options_header_count >= 2) {
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ }
+ *ext_hdrs |= OFPIEH12_FRAG;
+ break;
+
+ case IPPROTO_ROUTING:
+ if (*ext_hdrs & OFPIEH12_ROUTER)
+ *ext_hdrs |= OFPIEH12_UNREP;
+ if ((*ext_hdrs & ~(OFPIEH12_HOP |
+ OFPIEH12_DEST |
+ OFPIEH12_UNREP)) ||
+ dest_options_header_count >= 2) {
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ }
+ *ext_hdrs |= OFPIEH12_ROUTER;
+ break;
+
+ case IPPROTO_HOPOPTS:
+ if (*ext_hdrs & OFPIEH12_HOP)
+ *ext_hdrs |= OFPIEH12_UNREP;
+ /* OFPIEH12_HOP is set to 1 if a hop-by-hop IPv6
+ * extension header is present as the first
+ * extension header in the packet.
+ */
+ if (*ext_hdrs == 0)
+ *ext_hdrs |= OFPIEH12_HOP;
+ else
+ *ext_hdrs |= OFPIEH12_UNSEQ;
+ break;
+
+ default:
+ return;
+ }
+
+ hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
+ if (!hp)
+ break;
+ next_type = hp->nexthdr;
+ start += ipv6_optlen(hp);
+ };
+}
+
static int parse_ipv6hdr(struct sk_buff *skb, struct sw_flow_key *key)
{
unsigned short frag_off;
@@ -254,6 +392,8 @@ static int parse_ipv6hdr(struct sk_buff *skb, struct sw_flow_key *key)

nh = ipv6_hdr(skb);

+ get_ipv6_ext_hdrs(skb, nh, &key->ipv6.exthdrs);
+
key->ip.proto = NEXTHDR_NONE;
key->ip.tos = ipv6_get_dsfield(nh);
key->ip.ttl = nh->hop_limit;
diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h
index 758a8c77f736..073ab73ffeaa 100644
--- a/net/openvswitch/flow.h
+++ b/net/openvswitch/flow.h
@@ -32,6 +32,19 @@ enum sw_flow_mac_proto {
#define SW_FLOW_KEY_INVALID 0x80
#define MPLS_LABEL_DEPTH 3

+/* Bit definitions for IPv6 Extension Header pseudo-field. */
+enum ofp12_ipv6exthdr_flags {
+ OFPIEH12_NONEXT = 1 << 0, /* "No next header" encountered. */
+ OFPIEH12_ESP = 1 << 1, /* Encrypted Sec Payload header present. */
+ OFPIEH12_AUTH = 1 << 2, /* Authentication header present. */
+ OFPIEH12_DEST = 1 << 3, /* 1 or 2 dest headers present. */
+ OFPIEH12_FRAG = 1 << 4, /* Fragment header present. */
+ OFPIEH12_ROUTER = 1 << 5, /* Router header present. */
+ OFPIEH12_HOP = 1 << 6, /* Hop-by-hop header present. */
+ OFPIEH12_UNREP = 1 << 7, /* Unexpected repeats encountered. */
+ OFPIEH12_UNSEQ = 1 << 8 /* Unexpected sequencing encountered. */
+};
+
/* Store options at the end of the array if they are less than the
* maximum size. This allows us to get the benefits of variable length
* matching for small options.
@@ -121,6 +134,7 @@ struct sw_flow_key {
struct in6_addr dst; /* IPv6 destination address. */
} addr;
__be32 label; /* IPv6 flow label. */
+ u16 exthdrs; /* IPv6 extension header flags */
union {
struct {
struct in6_addr src;
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 65c2e3458ff5..2fbf324fcfff 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -367,7 +367,8 @@ size_t ovs_key_attr_size(void)
+ nla_total_size(2) /* OVS_KEY_ATTR_ETHERTYPE */
+ nla_total_size(40) /* OVS_KEY_ATTR_IPV6 */
+ nla_total_size(2) /* OVS_KEY_ATTR_ICMPV6 */
- + nla_total_size(28); /* OVS_KEY_ATTR_ND */
+ + nla_total_size(28) /* OVS_KEY_ATTR_ND */
+ + nla_total_size(2); /* OVS_KEY_ATTR_IPV6_EXTHDRS */
}

static const struct ovs_len_tbl ovs_vxlan_ext_key_lens[OVS_VXLAN_EXT_MAX + 1] = {
@@ -435,6 +436,8 @@ static const struct ovs_len_tbl ovs_key_lens[OVS_KEY_ATTR_MAX + 1] = {
.len = sizeof(struct ovs_key_ct_tuple_ipv6) },
[OVS_KEY_ATTR_NSH] = { .len = OVS_ATTR_NESTED,
.next = ovs_nsh_key_attr_lens, },
+ [OVS_KEY_ATTR_IPV6_EXTHDRS] = {
+ .len = sizeof(struct ovs_key_ipv6_exthdrs) },
};

static bool check_attr_len(unsigned int attr_len, unsigned int expected_len)
@@ -1595,6 +1598,17 @@ static int ovs_key_from_nlattrs(struct net *net, struct sw_flow_match *match,
attrs &= ~(1 << OVS_KEY_ATTR_IPV6);
}

+ if (attrs & (1ULL << OVS_KEY_ATTR_IPV6_EXTHDRS)) {
+ const struct ovs_key_ipv6_exthdrs *ipv6_exthdrs_key;
+
+ ipv6_exthdrs_key = nla_data(a[OVS_KEY_ATTR_IPV6_EXTHDRS]);
+
+ SW_FLOW_KEY_PUT(match, ipv6.exthdrs,
+ ipv6_exthdrs_key->hdrs, is_mask);
+
+ attrs &= ~(1ULL << OVS_KEY_ATTR_IPV6_EXTHDRS);
+ }
+
if (attrs & (1 << OVS_KEY_ATTR_ARP)) {
const struct ovs_key_arp *arp_key;

@@ -2097,6 +2111,7 @@ static int __ovs_nla_put_key(const struct sw_flow_key *swkey,
ipv4_key->ipv4_frag = output->ip.frag;
} else if (swkey->eth.type == htons(ETH_P_IPV6)) {
struct ovs_key_ipv6 *ipv6_key;
+ struct ovs_key_ipv6_exthdrs *ipv6_exthdrs_key;

nla = nla_reserve(skb, OVS_KEY_ATTR_IPV6, sizeof(*ipv6_key));
if (!nla)
@@ -2111,6 +2126,13 @@ static int __ovs_nla_put_key(const struct sw_flow_key *swkey,
ipv6_key->ipv6_tclass = output->ip.tos;
ipv6_key->ipv6_hlimit = output->ip.ttl;
ipv6_key->ipv6_frag = output->ip.frag;
+
+ nla = nla_reserve(skb, OVS_KEY_ATTR_IPV6_EXTHDRS,
+ sizeof(*ipv6_exthdrs_key));
+ if (!nla)
+ goto nla_put_failure;
+ ipv6_exthdrs_key = nla_data(nla);
+ ipv6_exthdrs_key->hdrs = output->ipv6.exthdrs;
} else if (swkey->eth.type == htons(ETH_P_NSH)) {
if (nsh_key_to_nlattr(&output->nsh, is_mask, skb))
goto nla_put_failure;
--
2.25.1