bpf: switch to using bpf_skb_utils.h

[project/qosify.git] / bpf_skb_utils.h

diff --git a/bpf_skb_utils.h b/bpf_skb_utils.h
new file mode 100644 (file)
index 0000000..a581d3e
--- /dev/null
+++ b/bpf_skb_utils.h
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022 Felix Fietkau <nbd@nbd.name>
+ * Version: 2022-09-21
+ */
+#ifndef __BPF_SKB_UTILS_H
+#define __BPF_SKB_UTILS_H
+
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/ip.h>
+#include <uapi/linux/ipv6.h>
+#include <linux/ip.h>
+#include <net/ipv6.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+struct skb_parser_info {
+       struct __sk_buff *skb;
+       __u32 offset;
+       int proto;
+};
+
+static __always_inline void *__skb_data(struct __sk_buff *skb)
+{
+       return (void *)(long)READ_ONCE(skb->data);
+}
+
+static __always_inline void *
+skb_ptr(struct __sk_buff *skb, __u32 offset, __u32 len)
+{
+       void *ptr = __skb_data(skb) + offset;
+       void *end = (void *)(long)(skb->data_end);
+
+       if (ptr + len >= end)
+               return NULL;
+
+       return ptr;
+}
+
+static __always_inline void *
+skb_info_ptr(struct skb_parser_info *info, __u32 len)
+{
+       __u32 offset = info->offset;
+       return skb_ptr(info->skb, offset, len);
+}
+
+static __always_inline void
+skb_parse_init(struct skb_parser_info *info, struct __sk_buff *skb)
+{
+       *info = (struct skb_parser_info){
+               .skb = skb
+       };
+}
+
+static __always_inline struct ethhdr *
+skb_parse_ethernet(struct skb_parser_info *info)
+{
+       struct ethhdr *eth;
+       int len;
+
+       len = sizeof(*eth) + 2 * sizeof(struct vlan_hdr) + sizeof(struct ipv6hdr);
+       if (len > info->skb->len)
+               len = info->skb->len;
+       bpf_skb_pull_data(info->skb, len);
+
+       eth = skb_info_ptr(info, sizeof(*eth));
+       if (!eth)
+               return NULL;
+
+       info->proto = eth->h_proto;
+       info->offset += sizeof(*eth);
+
+       return eth;
+}
+
+static __always_inline struct vlan_hdr *
+skb_parse_vlan(struct skb_parser_info *info)
+{
+       struct vlan_hdr *vlh;
+
+       if (info->proto != bpf_htons(ETH_P_8021Q) &&
+           info->proto != bpf_htons(ETH_P_8021AD))
+               return NULL;
+
+       vlh = skb_info_ptr(info, sizeof(*vlh));
+       if (!vlh)
+               return NULL;
+
+       info->proto = vlh->h_vlan_encapsulated_proto;
+       info->offset += sizeof(*vlh);
+
+       return vlh;
+}
+
+static __always_inline struct iphdr *
+skb_parse_ipv4(struct skb_parser_info *info, int min_l4_bytes)
+{
+       struct iphdr *iph;
+       int proto, hdr_len;
+       __u32 pull_len;
+
+       if (info->proto != bpf_htons(ETH_P_IP))
+               return NULL;
+
+       iph = skb_info_ptr(info, sizeof(*iph));
+       if (!iph)
+               return NULL;
+
+       hdr_len = iph->ihl * 4;
+       hdr_len = READ_ONCE(hdr_len) & 0xff;
+       if (hdr_len < sizeof(*iph))
+               return NULL;
+
+       pull_len = info->offset + hdr_len + min_l4_bytes;
+       if (pull_len > info->skb->len)
+               pull_len = info->skb->len;
+
+       if (bpf_skb_pull_data(info->skb, pull_len))
+               return NULL;
+
+       iph = skb_info_ptr(info, sizeof(*iph));
+       if (!iph)
+               return NULL;
+
+       info->proto = iph->protocol;
+       info->offset += hdr_len;
+
+       return iph;
+}
+
+static __always_inline struct ipv6hdr *
+skb_parse_ipv6(struct skb_parser_info *info, int max_l4_bytes)
+{
+       struct ipv6hdr *ip6h;
+       __u32 pull_len;
+
+       if (info->proto != bpf_htons(ETH_P_IPV6))
+               return NULL;
+
+       pull_len = info->offset + sizeof(*ip6h) + max_l4_bytes;
+       if (pull_len > info->skb->len)
+               pull_len = info->skb->len;
+
+       if (bpf_skb_pull_data(info->skb, pull_len))
+               return NULL;
+
+       ip6h = skb_info_ptr(info, sizeof(*ip6h));
+       if (!ip6h)
+               return NULL;
+
+       info->proto = READ_ONCE(ip6h->nexthdr);
+       info->offset += sizeof(*ip6h);
+
+       return ip6h;
+}
+
+static __always_inline struct tcphdr *
+skb_parse_tcp(struct skb_parser_info *info)
+{
+       struct tcphdr *tcph;
+
+       if (info->proto != IPPROTO_TCP)
+               return NULL;
+
+       tcph = skb_info_ptr(info, sizeof(*tcph));
+       if (!tcph)
+               return NULL;
+
+       info->offset += tcph->doff * 4;
+
+       return tcph;
+}
+
+#endif