Messages in this thread | | | Date | Tue, 03 Oct 2017 17:54:10 +0200 | From | Daniel Borkmann <> | Subject | Re: [PATCH 1/1] xdp: Sample xdp program implementing ip forward |
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On 10/03/2017 09:37 AM, cjacob wrote: > Implements port to port forwarding with route table and arp table > lookup for ipv4 packets using bpf_redirect helper function and > lpm_trie map. > > Signed-off-by: cjacob <Christina.Jacob@cavium.com>
Thanks for the patch, just few minor comments below!
Note, should be full name, e.g.:
Signed-off-by: Christina Jacob <Christina.Jacob@cavium.com>
Also you From: only shows 'cjacob' as can be seen from the cover letter as well, so perhaps check your git settings to make that full name:
cjacob (1): xdp: Sample xdp program implementing ip forward
If there's one single patch, then cover letter is not needed, only for >1 sets.
[...] > +#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 "bpf_helpers.h" > +#include <linux/slab.h> > +#include <net/ip_fib.h> > + > +struct trie_value { > + __u8 prefix[4]; > + long value; > + int gw; > + int ifindex; > + int metric; > +}; > + > +union key_4 { > + u32 b32[2]; > + u8 b8[8]; > +}; > + > +struct arp_entry { > + int dst; > + long mac; > +}; > + > +struct direct_map { > + long mac; > + int ifindex; > + struct arp_entry arp; > +}; > + > +/* Map for trie implementation*/ > +struct bpf_map_def SEC("maps") lpm_map = { > + .type = BPF_MAP_TYPE_LPM_TRIE, > + .key_size = 8, > + .value_size = > + sizeof(struct trie_value),
(Nit: there are couple of such breaks throughout the patch, can we just use single line for such cases where reasonable?)
> + .max_entries = 50, > + .map_flags = BPF_F_NO_PREALLOC, > +}; > + > +/* Map for counter*/ > +struct bpf_map_def SEC("maps") rxcnt = { > + .type = BPF_MAP_TYPE_PERCPU_ARRAY, > + .key_size = sizeof(u32), > + .value_size = sizeof(long), > + .max_entries = 256, > +}; > + > +/* Map for ARP table*/ > +struct bpf_map_def SEC("maps") arp_table = { > + .type = BPF_MAP_TYPE_HASH, > + .key_size = sizeof(int), > + .value_size = sizeof(long),
Perhaps these should be proper structs here, such that it becomes easier to read/handle later on lookup.
> + .max_entries = 50, > +}; > + > +/* Map to keep the exact match entries in the route table*/ > +struct bpf_map_def SEC("maps") exact_match = { > + .type = BPF_MAP_TYPE_HASH, > + .key_size = sizeof(int), > + .value_size = sizeof(struct direct_map), > + .max_entries = 50, > +}; > + > +/** > + * Function to set source and destination mac of the packet > + */ > +static inline void set_src_dst_mac(void *data, void *src, void *dst) > +{ > + unsigned short *p = data; > + unsigned short *dest = dst; > + unsigned short *source = src; > + > + p[3] = source[0]; > + p[4] = source[1]; > + p[5] = source[2]; > + p[0] = dest[0]; > + p[1] = dest[1]; > + p[2] = dest[2];
You could just use __builtin_memcpy() given length is constant anyway, so LLVM will do the inlining.
> +} > + > +/** > + * Parse IPV4 packet to get SRC, DST IP and protocol > + */ > +static inline int parse_ipv4(void *data, u64 nh_off, void *data_end, > + unsigned int *src, unsigned int *dest) > +{ > + struct iphdr *iph = data + nh_off; > + > + if (iph + 1 > data_end) > + return 0; > + *src = (unsigned int)iph->saddr; > + *dest = (unsigned int)iph->daddr;
Why not stay with __be32 types?
> + return iph->protocol; > +} > + > +SEC("xdp3") > +int xdp_prog3(struct xdp_md *ctx) > +{ > + void *data_end = (void *)(long)ctx->data_end; > + void *data = (void *)(long)ctx->data; > + struct ethhdr *eth = data; > + int rc = XDP_DROP, forward_to; > + long *value; > + struct trie_value *prefix_value; > + long *dest_mac = NULL, *src_mac = NULL; > + u16 h_proto; > + u64 nh_off; > + u32 ipproto; > + union key_4 key4; > + > + nh_off = sizeof(*eth); > + if (data + nh_off > data_end) > + return rc; > + > + h_proto = eth->h_proto; > + > + if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) { > + struct vlan_hdr *vhdr; > + > + vhdr = data + nh_off; > + nh_off += sizeof(struct vlan_hdr); > + if (data + nh_off > data_end) > + return rc; > + h_proto = vhdr->h_vlan_encapsulated_proto; > + } > + if (h_proto == htons(ETH_P_ARP)) { > + return XDP_PASS; > + } else if (h_proto == htons(ETH_P_IP)) { > + int src_ip = 0, dest_ip = 0; > + struct direct_map *direct_entry; > + > + ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip); > + direct_entry = (struct direct_map *)bpf_map_lookup_elem > + (&exact_match, &dest_ip); > + /*check for exact match, this would give a faster lookup*/ > + if (direct_entry && direct_entry->mac && > + direct_entry->arp.mac) { > + src_mac = &direct_entry->mac; > + dest_mac = &direct_entry->arp.mac; > + forward_to = direct_entry->ifindex; > + } else { > + /*Look up in the trie for lpm*/ > + // Key for trie
Nit: please check style throughout the patch.
> + key4.b32[0] = 32; > + key4.b8[4] = dest_ip % 0x100; > + key4.b8[5] = (dest_ip >> 8) % 0x100; > + key4.b8[6] = (dest_ip >> 16) % 0x100; > + key4.b8[7] = (dest_ip >> 24) % 0x100; > + prefix_value = > + ((struct trie_value *)bpf_map_lookup_elem > + (&lpm_map, &key4));
For key, please use proper struct bpf_lpm_trie_key, see also usage example in tools/testing/selftests/bpf/test_lpm_map.c for LPM handling.
> + if (!prefix_value) { > + return XDP_DROP; > + } else { > + src_mac = &prefix_value->value; > + if (src_mac) { > + dest_mac = (long *)bpf_map_lookup_elem > + (&arp_table, &dest_ip); > + if (!dest_mac) { > + if (prefix_value->gw) { > + dest_ip = *(unsigned int *)(&(prefix_value->gw)); > + dest_mac = (long *)bpf_map_lookup_elem > + (&arp_table, &dest_ip); > + } else { > + return XDP_DROP; > + } > + } > + forward_to = prefix_value->ifindex; > + } else { > + return XDP_DROP; > + } > + } > + } > + } else { > + ipproto = 0; > + } > + if (src_mac && dest_mac) { > + set_src_dst_mac(data, src_mac, > + dest_mac); > + value = bpf_map_lookup_elem > + (&rxcnt, &ipproto); > + if (value) > + *value += 1; > + return bpf_redirect( > + forward_to, > + 0); > + } > + return rc;
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