BPF prog for XDP parses the packet and extracts the flow key. Then find
an entry from flow tables.
Only "accept" and "drop" actions are implemented at this point.
Signed-off-by: Toshiaki Makita <toshiaki.makita1@xxxxxxxxx>
---
net/xdp_flow/xdp_flow_kern_bpf.c | 297 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 296 insertions(+), 1 deletion(-)
diff --git a/net/xdp_flow/xdp_flow_kern_bpf.c b/net/xdp_flow/xdp_flow_kern_bpf.c
index c101156..f4a6346 100644
--- a/net/xdp_flow/xdp_flow_kern_bpf.c
+++ b/net/xdp_flow/xdp_flow_kern_bpf.c
@@ -1,9 +1,27 @@
// SPDX-License-Identifier: GPL-2.0
#define KBUILD_MODNAME "foo"
#include <uapi/linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/ipv6.h>
+#include <net/dsfield.h>
#include <bpf_helpers.h>
#include "umh_bpf.h"
+/* Used when the action only modifies the packet */
+#define _XDP_CONTINUE -1
+
+struct bpf_map_def SEC("maps") debug_stats = {
+ .type = BPF_MAP_TYPE_PERCPU_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(long),
+ .max_entries = 256,
+};
+
struct bpf_map_def SEC("maps") flow_masks_head = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(u32),
@@ -25,10 +43,287 @@ struct bpf_map_def SEC("maps") flow_tables = {
.max_entries = MAX_FLOW_MASKS,
};
+static inline void account_debug(int idx)
+{
+ long *cnt;
+
+ cnt = bpf_map_lookup_elem(&debug_stats, &idx);
+ if (cnt)
+ *cnt += 1;
+}
+
+static inline void account_action(int act)
+{
+ account_debug(act + 1);
+}
+
+static inline int action_accept(void)
+{
+ account_action(XDP_FLOW_ACTION_ACCEPT);
+ return XDP_PASS;
+}
+
+static inline int action_drop(void)
+{
+ account_action(XDP_FLOW_ACTION_DROP);
+ return XDP_DROP;
+}
+
+static inline int action_redirect(struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_REDIRECT);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline int action_vlan_push(struct xdp_md *ctx,
+ struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_VLAN_PUSH);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline int action_vlan_pop(struct xdp_md *ctx,
+ struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_VLAN_POP);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline int action_vlan_mangle(struct xdp_md *ctx,
+ struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_VLAN_MANGLE);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline int action_mangle(struct xdp_md *ctx,
+ struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_MANGLE);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline int action_csum(struct xdp_md *ctx,
+ struct xdp_flow_action *action)
+{
+ account_action(XDP_FLOW_ACTION_CSUM);
+
+ // TODO: implement this
+ return XDP_ABORTED;
+}
+
+static inline void __ether_addr_copy(u8 *dst, const u8 *src)
+{
+ u16 *a = (u16 *)dst;
+ const u16 *b = (const u16 *)src;
+
+ a[0] = b[0];
+ a[1] = b[1];
+ a[2] = b[2];
+}
+
+static inline int parse_ipv4(void *data, u64 *nh_off, void *data_end,
+ struct xdp_flow_key *key)
+{
+ struct iphdr *iph = data + *nh_off;
+
+ if (iph + 1 > data_end)
+ return -1;
+
+ key->ipv4.src = iph->saddr;
+ key->ipv4.dst = iph->daddr;
+ key->ip.ttl = iph->ttl;
+ key->ip.tos = iph->tos;
+ *nh_off += iph->ihl * 4;
+
+ return iph->protocol;
+}
+
+static inline int parse_ipv6(void *data, u64 *nh_off, void *data_end,
+ struct xdp_flow_key *key)
+{
+ struct ipv6hdr *ip6h = data + *nh_off;
+
+ if (ip6h + 1 > data_end)
+ return -1;
+
+ key->ipv6.src = ip6h->saddr;
+ key->ipv6.dst = ip6h->daddr;
+ key->ip.ttl = ip6h->hop_limit;
+ key->ip.tos = ipv6_get_dsfield(ip6h);
+ *nh_off += sizeof(*ip6h);
+
+ if (ip6h->nexthdr == NEXTHDR_HOP ||
+ ip6h->nexthdr == NEXTHDR_ROUTING ||
+ ip6h->nexthdr == NEXTHDR_FRAGMENT ||
+ ip6h->nexthdr == NEXTHDR_AUTH ||
+ ip6h->nexthdr == NEXTHDR_NONE ||
+ ip6h->nexthdr == NEXTHDR_DEST)
+ return 0;
+
+ return ip6h->nexthdr;
+}
+
+#define for_each_flow_mask(entry, head, idx, cnt) \
+ for (entry = bpf_map_lookup_elem(&flow_masks, (head)), \
+ idx = *(head), cnt = 0; \
+ entry != NULL && cnt < MAX_FLOW_MASKS; \
+ idx = entry->next, \
+ entry = bpf_map_lookup_elem(&flow_masks, &idx), cnt++)
+
+static inline void flow_mask(struct xdp_flow_key *mkey,
+ const struct xdp_flow_key *key,
+ const struct xdp_flow_key *mask)
+{
+ long *lmkey = (long *)mkey;
+ long *lmask = (long *)mask;
+ long *lkey = (long *)key;
+ int i;
+
+ for (i = 0; i < sizeof(*mkey); i += sizeof(long))
+ *lmkey++ = *lkey++ & *lmask++;
+}
+
SEC("xdp_flow")
int xdp_flow_prog(struct xdp_md *ctx)
{
- return XDP_PASS;
+ void *data_end = (void *)(long)ctx->data_end;
+ struct xdp_flow_actions *actions = NULL;
+ void *data = (void *)(long)ctx->data;
+ int cnt, idx, action_idx, zero = 0;
+ struct xdp_flow_mask_entry *entry;
+ struct ethhdr *eth = data;
+ struct xdp_flow_key key;
+ int rc = XDP_DROP;
+ long *value;
+ u16 h_proto;
+ int ipproto;
+ u64 nh_off;
+ int *head;
+
+ account_debug(0);
+
+ nh_off = sizeof(*eth);
+ if (data + nh_off > data_end)
+ return XDP_DROP;
+
+ __builtin_memset(&key, 0, sizeof(key));
+ h_proto = eth->h_proto;
+ __ether_addr_copy(key.eth.dst, eth->h_dest);
+ __ether_addr_copy(key.eth.src, eth->h_source);
+
+ if (eth_type_vlan(h_proto)) {
+ struct vlan_hdr *vhdr;
+
+ vhdr = data + nh_off;
+ nh_off += sizeof(*vhdr);
+ if (data + nh_off > data_end)
+ return XDP_DROP;
+ key.vlan.tpid = h_proto;
+ key.vlan.tci = vhdr->h_vlan_TCI;
+ h_proto = vhdr->h_vlan_encapsulated_proto;
+ }
+ key.eth.type = h_proto;
+
+ if (h_proto == htons(ETH_P_IP))
+ ipproto = parse_ipv4(data, &nh_off, data_end, &key);
+ else if (h_proto == htons(ETH_P_IPV6))
+ ipproto = parse_ipv6(data, &nh_off, data_end, &key);
+ else
+ ipproto = 0;
+ if (ipproto < 0)
+ return XDP_DROP;
+ key.ip.proto = ipproto;
+
+ if (ipproto == IPPROTO_TCP) {
+ struct tcphdr *th = data + nh_off;
+
+ if (th + 1 > data_end)
+ return XDP_DROP;
+
+ key.l4port.src = th->source;
+ key.l4port.dst = th->dest;
+ key.tcp.flags = (*(__be16 *)&tcp_flag_word(th) & htons(0x0FFF));
+ } else if (ipproto == IPPROTO_UDP) {
+ struct udphdr *uh = data + nh_off;
+
+ if (uh + 1 > data_end)
+ return XDP_DROP;
+
+ key.l4port.src = uh->source;
+ key.l4port.dst = uh->dest;
+ }
+
+ head = bpf_map_lookup_elem(&flow_masks_head, &zero);
+ if (!head)
+ return XDP_PASS;
+
+ for_each_flow_mask(entry, head, idx, cnt) {
+ struct xdp_flow_key mkey;
+ void *flow_table;
+
+ flow_table = bpf_map_lookup_elem(&flow_tables, &idx);
+ if (!flow_table)
+ return XDP_ABORTED;
+
+ flow_mask(&mkey, &key, &entry->mask);
+ actions = bpf_map_lookup_elem(flow_table, &mkey);
+ if (actions)
+ break;
+ }
+
+ if (!actions)
+ return XDP_PASS;
+
+ for (action_idx = 0;
+ action_idx < actions->num_actions &&
+ action_idx < MAX_XDP_FLOW_ACTIONS;
+ action_idx++) {
+ struct xdp_flow_action *action;
+ int act;
+
+ action = &actions->actions[action_idx];
+
+ switch (action->id) {
+ case XDP_FLOW_ACTION_ACCEPT:
+ return action_accept();
+ case XDP_FLOW_ACTION_DROP:
+ return action_drop();
+ case XDP_FLOW_ACTION_REDIRECT:
+ return action_redirect(action);
+ case XDP_FLOW_ACTION_VLAN_PUSH:
+ act = action_vlan_push(ctx, action);
+ break;
+ case XDP_FLOW_ACTION_VLAN_POP:
+ act = action_vlan_pop(ctx, action);
+ break;
+ case XDP_FLOW_ACTION_VLAN_MANGLE:
+ act = action_vlan_mangle(ctx, action);
+ break;
+ case XDP_FLOW_ACTION_MANGLE:
+ act = action_mangle(ctx, action);
+ break;
+ case XDP_FLOW_ACTION_CSUM:
+ act = action_csum(ctx, action);
+ break;
+ default:
+ return XDP_ABORTED;
+ }
+ if (act != _XDP_CONTINUE)
+ return act;
+ }
+
+ return XDP_ABORTED;
}
char _license[] SEC("license") = "GPL";
--
1.8.3.1
