[ovs-dev] [PATCH 2/6] vxlan: Group Policy extension
Nicolas Dichtel
nicolas.dichtel at 6wind.com
Mon Jan 12 17:37:37 UTC 2015
Le 08/01/2015 23:47, Thomas Graf a écrit :
> Implements supports for the Group Policy VXLAN extension [0] to provide
> a lightweight and simple security label mechanism across network peers
> based on VXLAN. The security context and associated metadata is mapped
> to/from skb->mark. This allows further mapping to a SELinux context
> using SECMARK, to implement ACLs directly with nftables, iptables, OVS,
> tc, etc.
>
> The group membership is defined by the lower 16 bits of skb->mark, the
> upper 16 bits are used for flags.
>
> SELinux allows to manage label to secure local resources. However,
> distributed applications require ACLs to implemented across hosts. This
> is typically achieved by matching on L2-L4 fields to identify the
> original sending host and process on the receiver. On top of that,
> netlabel and specifically CIPSO [1] allow to map security contexts to
> universal labels. However, netlabel and CIPSO are relatively complex.
> This patch provides a lightweight alternative for overlay network
> environments with a trusted underlay. No additional control protocol
> is required.
>
> Host 1: Host 2:
>
> Group A Group B Group B Group A
> +-----+ +-------------+ +-------+ +-----+
> | lxc | | SELinux CTX | | httpd | | VM |
> +--+--+ +--+----------+ +---+---+ +--+--+
> \---+---/ \----+---/
> | |
> +---+---+ +---+---+
> | vxlan | | vxlan |
> +---+---+ +---+---+
> +------------------------------+
>
> Backwards compatibility:
> A VXLAN-GBP socket can receive standard VXLAN frames and will assign
> the default group 0x0000 to such frames. A Linux VXLAN socket will
> drop VXLAN-GBP frames. The extension is therefore disabled by default
> and needs to be specifically enabled:
>
> ip link add [...] type vxlan [...] gbp
>
> In a mixed environment with VXLAN and VXLAN-GBP sockets, the GBP socket
> must run on a separate port number.
>
> Examples:
> iptables:
> host1# iptables -I OUTPUT -m owner --uid-owner 101 -j MARK --set-mark 0x200
> host2# iptables -I INPUT -m mark --mark 0x200 -j DROP
>
> OVS:
> # ovs-ofctl add-flow br0 'in_port=1,actions=load:0x200->NXM_NX_TUN_GBP_ID[],NORMAL'
> # ovs-ofctl add-flow br0 'in_port=2,tun_gbp_id=0x200,actions=drop'
>
> [0] https://tools.ietf.org/html/draft-smith-vxlan-group-policy
> [1] http://lwn.net/Articles/204905/
>
> Signed-off-by: Thomas Graf <tgraf at suug.ch>
> ---
> v2:
> - split GBP header definition into separate struct vxlanhdr_gbp as requested
> by Alexei
>
> drivers/net/vxlan.c | 161 ++++++++++++++++++++++++++++++------------
> include/net/vxlan.h | 73 +++++++++++++++++--
> include/uapi/linux/if_link.h | 8 +++
> net/openvswitch/vport-vxlan.c | 9 ++-
> 4 files changed, 198 insertions(+), 53 deletions(-)
>
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 4d52aa9..b148739 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -132,6 +132,7 @@ struct vxlan_dev {
> __u8 tos; /* TOS override */
> __u8 ttl;
> u32 flags; /* VXLAN_F_* in vxlan.h */
> + u32 exts; /* Enabled extensions */
>
> struct work_struct sock_work;
> struct work_struct igmp_join;
> @@ -568,7 +569,8 @@ static struct sk_buff **vxlan_gro_receive(struct sk_buff **head, struct sk_buff
> continue;
>
> vh2 = (struct vxlanhdr *)(p->data + off_vx);
> - if (vh->vx_vni != vh2->vx_vni) {
> + if (vh->vx_flags != vh2->vx_flags ||
> + vh->vx_vni != vh2->vx_vni) {
> NAPI_GRO_CB(p)->same_flow = 0;
> continue;
> }
> @@ -1095,6 +1097,7 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
> {
> struct vxlan_sock *vs;
> struct vxlanhdr *vxh;
> + struct vxlan_metadata md = {0};
>
> /* Need Vxlan and inner Ethernet header to be present */
> if (!pskb_may_pull(skb, VXLAN_HLEN))
> @@ -1113,6 +1116,22 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
> if (vs->exts) {
> if (!vxh->vni_present)
> goto error_invalid_header;
> +
> + if (vxh->gbp_present) {
> + struct vxlanhdr_gbp *gbp;
> +
> + if (!(vs->exts & VXLAN_EXT_GBP))
> + goto error_invalid_header;
> +
> + gbp = (struct vxlanhdr_gbp *)vxh;
> + md.gbp = ntohs(gbp->policy_id);
> +
> + if (gbp->dont_learn)
> + md.gbp |= VXLAN_GBP_DONT_LEARN;
> +
> + if (gbp->policy_applied)
> + md.gbp |= VXLAN_GBP_POLICY_APPLIED;
> + }
> } else {
> if (vxh->vx_flags != htonl(VXLAN_FLAGS) ||
> (vxh->vx_vni & htonl(0xff)))
> @@ -1122,7 +1141,8 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
> if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB)))
> goto drop;
>
> - vs->rcv(vs, skb, vxh->vx_vni);
> + md.vni = vxh->vx_vni;
> + vs->rcv(vs, skb, &md);
> return 0;
>
> drop:
> @@ -1138,8 +1158,8 @@ error:
> return 1;
> }
>
> -static void vxlan_rcv(struct vxlan_sock *vs,
> - struct sk_buff *skb, __be32 vx_vni)
> +static void vxlan_rcv(struct vxlan_sock *vs, struct sk_buff *skb,
> + struct vxlan_metadata *md)
> {
> struct iphdr *oip = NULL;
> struct ipv6hdr *oip6 = NULL;
> @@ -1150,7 +1170,7 @@ static void vxlan_rcv(struct vxlan_sock *vs,
> int err = 0;
> union vxlan_addr *remote_ip;
>
> - vni = ntohl(vx_vni) >> 8;
> + vni = ntohl(md->vni) >> 8;
> /* Is this VNI defined? */
> vxlan = vxlan_vs_find_vni(vs, vni);
> if (!vxlan)
> @@ -1184,6 +1204,7 @@ static void vxlan_rcv(struct vxlan_sock *vs,
> goto drop;
>
> skb_reset_network_header(skb);
> + skb->mark = md->gbp;
>
> if (oip6)
> err = IP6_ECN_decapsulate(oip6, skb);
> @@ -1533,15 +1554,57 @@ static bool route_shortcircuit(struct net_device *dev, struct sk_buff *skb)
> return false;
> }
>
> +static int vxlan_build_hdr(struct sk_buff *skb, struct vxlan_sock *vs,
> + int min_headroom, struct vxlan_metadata *md)
> +{
> + struct vxlanhdr *vxh;
> + int err;
> +
> + /* Need space for new headers (invalidates iph ptr) */
> + err = skb_cow_head(skb, min_headroom);
> + if (unlikely(err)) {
> + kfree_skb(skb);
> + return err;
> + }
> +
> + skb = vlan_hwaccel_push_inside(skb);
> + if (WARN_ON(!skb))
> + return -ENOMEM;
> +
> + vxh = (struct vxlanhdr *)__skb_push(skb, sizeof(*vxh));
> + vxh->vx_flags = htonl(VXLAN_FLAGS);
> + vxh->vx_vni = md->vni;
> +
> + if (vs->exts) {
> + if (vs->exts & VXLAN_EXT_GBP) {
> + struct vxlanhdr_gbp *gbp;
> +
> + gbp = (struct vxlanhdr_gbp *)vxh;
> + vxh->gbp_present = 1;
> +
> + if (md->gbp & VXLAN_GBP_DONT_LEARN)
> + gbp->dont_learn = 1;
> +
> + if (md->gbp & VXLAN_GBP_POLICY_APPLIED)
> + gbp->policy_applied = 1;
> +
> + gbp->policy_id = htons(md->gbp & VXLAN_GBP_ID_MASK);
> + }
> + }
> +
> + skb_set_inner_protocol(skb, htons(ETH_P_TEB));
> +
> + return 0;
> +}
> +
> #if IS_ENABLED(CONFIG_IPV6)
> static int vxlan6_xmit_skb(struct vxlan_sock *vs,
> struct dst_entry *dst, struct sk_buff *skb,
> struct net_device *dev, struct in6_addr *saddr,
> struct in6_addr *daddr, __u8 prio, __u8 ttl,
> - __be16 src_port, __be16 dst_port, __be32 vni,
> - bool xnet)
> + __be16 src_port, __be16 dst_port,
> + struct vxlan_metadata *md, bool xnet)
> {
> - struct vxlanhdr *vxh;
> int min_headroom;
> int err;
> bool udp_sum = !udp_get_no_check6_tx(vs->sock->sk);
> @@ -1558,24 +1621,9 @@ static int vxlan6_xmit_skb(struct vxlan_sock *vs,
> + VXLAN_HLEN + sizeof(struct ipv6hdr)
> + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
>
> - /* Need space for new headers (invalidates iph ptr) */
> - err = skb_cow_head(skb, min_headroom);
> - if (unlikely(err)) {
> - kfree_skb(skb);
> - goto err;
> - }
> -
> - skb = vlan_hwaccel_push_inside(skb);
> - if (WARN_ON(!skb)) {
> - err = -ENOMEM;
> + err = vxlan_build_hdr(skb, vs, min_headroom, md);
> + if (err)
> goto err;
> - }
> -
> - vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
> - vxh->vx_flags = htonl(VXLAN_FLAGS);
> - vxh->vx_vni = vni;
> -
> - skb_set_inner_protocol(skb, htons(ETH_P_TEB));
>
> udp_tunnel6_xmit_skb(vs->sock, dst, skb, dev, saddr, daddr, prio,
> ttl, src_port, dst_port);
> @@ -1589,9 +1637,9 @@ err:
> int vxlan_xmit_skb(struct vxlan_sock *vs,
> struct rtable *rt, struct sk_buff *skb,
> __be32 src, __be32 dst, __u8 tos, __u8 ttl, __be16 df,
> - __be16 src_port, __be16 dst_port, __be32 vni, bool xnet)
> + __be16 src_port, __be16 dst_port,
> + struct vxlan_metadata *md, bool xnet)
> {
> - struct vxlanhdr *vxh;
> int min_headroom;
> int err;
> bool udp_sum = !vs->sock->sk->sk_no_check_tx;
> @@ -1604,22 +1652,9 @@ int vxlan_xmit_skb(struct vxlan_sock *vs,
> + VXLAN_HLEN + sizeof(struct iphdr)
> + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
>
> - /* Need space for new headers (invalidates iph ptr) */
> - err = skb_cow_head(skb, min_headroom);
> - if (unlikely(err)) {
> - kfree_skb(skb);
> + err = vxlan_build_hdr(skb, vs, min_headroom, md);
> + if (err)
> return err;
> - }
> -
> - skb = vlan_hwaccel_push_inside(skb);
> - if (WARN_ON(!skb))
> - return -ENOMEM;
> -
> - vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
> - vxh->vx_flags = htonl(VXLAN_FLAGS);
> - vxh->vx_vni = vni;
> -
> - skb_set_inner_protocol(skb, htons(ETH_P_TEB));
>
> return udp_tunnel_xmit_skb(vs->sock, rt, skb, src, dst, tos,
> ttl, df, src_port, dst_port, xnet);
> @@ -1679,6 +1714,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
> const struct iphdr *old_iph;
> struct flowi4 fl4;
> union vxlan_addr *dst;
> + struct vxlan_metadata md;
> __be16 src_port = 0, dst_port;
> u32 vni;
> __be16 df = 0;
> @@ -1749,11 +1785,12 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
>
> tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
> ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
> + md.vni = htonl(vni << 8);
> + md.gbp = skb->mark;
>
> err = vxlan_xmit_skb(vxlan->vn_sock, rt, skb,
> fl4.saddr, dst->sin.sin_addr.s_addr,
> - tos, ttl, df, src_port, dst_port,
> - htonl(vni << 8),
> + tos, ttl, df, src_port, dst_port, &md,
> !net_eq(vxlan->net, dev_net(vxlan->dev)));
> if (err < 0) {
> /* skb is already freed. */
> @@ -1806,10 +1843,12 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
> }
>
> ttl = ttl ? : ip6_dst_hoplimit(ndst);
> + md.vni = htonl(vni << 8);
> + md.gbp = skb->mark;
>
> err = vxlan6_xmit_skb(vxlan->vn_sock, ndst, skb,
> dev, &fl6.saddr, &fl6.daddr, 0, ttl,
> - src_port, dst_port, htonl(vni << 8),
> + src_port, dst_port, &md,
> !net_eq(vxlan->net, dev_net(vxlan->dev)));
> #endif
> }
> @@ -2210,6 +2249,11 @@ static const struct nla_policy vxlan_policy[IFLA_VXLAN_MAX + 1] = {
> [IFLA_VXLAN_UDP_CSUM] = { .type = NLA_U8 },
> [IFLA_VXLAN_UDP_ZERO_CSUM6_TX] = { .type = NLA_U8 },
> [IFLA_VXLAN_UDP_ZERO_CSUM6_RX] = { .type = NLA_U8 },
> + [IFLA_VXLAN_EXTENSION] = { .type = NLA_NESTED },
> +};
> +
> +static const struct nla_policy vxlan_ext_policy[IFLA_VXLAN_EXT_MAX + 1] = {
> + [IFLA_VXLAN_EXT_GBP] = { .type = NLA_FLAG, },
> };
>
> static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[])
> @@ -2246,6 +2290,18 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[])
> }
> }
>
> + if (data[IFLA_VXLAN_EXTENSION]) {
> + int err;
> +
> + err = nla_validate_nested(data[IFLA_VXLAN_EXTENSION],
> + IFLA_VXLAN_EXT_MAX, vxlan_ext_policy);
> + if (err < 0) {
> + pr_debug("invalid VXLAN extension configuration: %d\n",
> + err);
> + return -EINVAL;
> + }
> + }
> +
> return 0;
> }
>
> @@ -2400,6 +2456,18 @@ static void vxlan_sock_work(struct work_struct *work)
> dev_put(vxlan->dev);
> }
>
> +static void configure_vxlan_exts(struct vxlan_dev *vxlan, struct nlattr *attr)
> +{
> + struct nlattr *exts[IFLA_VXLAN_EXT_MAX+1];
> +
> + /* Validated in vxlan_validate() */
> + if (nla_parse_nested(exts, IFLA_VXLAN_EXT_MAX, attr, NULL) < 0)
> + BUG();
> +
> + if (exts[IFLA_VXLAN_EXT_GBP])
> + vxlan->exts |= VXLAN_EXT_GBP;
> +}
> +
> static int vxlan_newlink(struct net *net, struct net_device *dev,
> struct nlattr *tb[], struct nlattr *data[])
> {
> @@ -2525,6 +2593,9 @@ static int vxlan_newlink(struct net *net, struct net_device *dev,
> nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX]))
> vxlan->flags |= VXLAN_F_UDP_ZERO_CSUM6_RX;
>
> + if (data[IFLA_VXLAN_EXTENSION])
> + configure_vxlan_exts(vxlan, data[IFLA_VXLAN_EXTENSION]);
> +
Can you also update vxlan_fill_info() so that these new attributes can be dumped
via netlink?
Thank you,
Nicolas
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