1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #pragma once
18
19 #include <linux/bpf.h>
20 #include <linux/if_packet.h>
21 #include <stdbool.h>
22 #include <stdint.h>
23
24 // bionic kernel uapi linux/udp.h header is munged...
25 #define __kernel_udphdr udphdr
26 #include <linux/udp.h>
27
28 // Offsets from beginning of L4 (TCP/UDP) header
29 #define TCP_OFFSET(field) offsetof(struct tcphdr, field)
30 #define UDP_OFFSET(field) offsetof(struct udphdr, field)
31
32 // Offsets from beginning of L3 (IPv4/IPv6) header
33 #define IP4_OFFSET(field) offsetof(struct iphdr, field)
34 #define IP6_OFFSET(field) offsetof(struct ipv6hdr, field)
35
36 // this returns 0 iff skb->sk is NULL
37 static uint64_t (*bpf_get_socket_cookie)(struct __sk_buff* skb) = (void*)BPF_FUNC_get_socket_cookie;
38 static uint64_t (*bpf_get_sk_cookie)(struct bpf_sock* sk) = (void*)BPF_FUNC_get_socket_cookie;
39
40 static uint32_t (*bpf_get_socket_uid)(struct __sk_buff* skb) = (void*)BPF_FUNC_get_socket_uid;
41
42 static int (*bpf_skb_pull_data)(struct __sk_buff* skb, __u32 len) = (void*)BPF_FUNC_skb_pull_data;
43
44 static int (*bpf_skb_load_bytes)(const struct __sk_buff* skb, int off, void* to,
45 int len) = (void*)BPF_FUNC_skb_load_bytes;
46
47 static int (*bpf_skb_load_bytes_relative)(const struct __sk_buff* skb, int off, void* to, int len,
48 int start_hdr) = (void*)BPF_FUNC_skb_load_bytes_relative;
49
50 static int (*bpf_skb_store_bytes)(struct __sk_buff* skb, __u32 offset, const void* from, __u32 len,
51 __u64 flags) = (void*)BPF_FUNC_skb_store_bytes;
52
53 static int64_t (*bpf_csum_diff)(__be32* from, __u32 from_size, __be32* to, __u32 to_size,
54 __wsum seed) = (void*)BPF_FUNC_csum_diff;
55
56 static int64_t (*bpf_csum_update)(struct __sk_buff* skb, __wsum csum) = (void*)BPF_FUNC_csum_update;
57
58 static int (*bpf_skb_change_proto)(struct __sk_buff* skb, __be16 proto,
59 __u64 flags) = (void*)BPF_FUNC_skb_change_proto;
60 static int (*bpf_l3_csum_replace)(struct __sk_buff* skb, __u32 offset, __u64 from, __u64 to,
61 __u64 flags) = (void*)BPF_FUNC_l3_csum_replace;
62 static int (*bpf_l4_csum_replace)(struct __sk_buff* skb, __u32 offset, __u64 from, __u64 to,
63 __u64 flags) = (void*)BPF_FUNC_l4_csum_replace;
64 static int (*bpf_redirect)(__u32 ifindex, __u64 flags) = (void*)BPF_FUNC_redirect;
65 static int (*bpf_redirect_map)(const struct bpf_map_def* map, __u32 key,
66 __u64 flags) = (void*)BPF_FUNC_redirect_map;
67
68 static int (*bpf_skb_change_head)(struct __sk_buff* skb, __u32 head_room,
69 __u64 flags) = (void*)BPF_FUNC_skb_change_head;
70 static int (*bpf_skb_adjust_room)(struct __sk_buff* skb, __s32 len_diff, __u32 mode,
71 __u64 flags) = (void*)BPF_FUNC_skb_adjust_room;
72
73 // Android only supports little endian architectures
74 #define htons(x) (__builtin_constant_p(x) ? ___constant_swab16(x) : __builtin_bswap16(x))
75 #define htonl(x) (__builtin_constant_p(x) ? ___constant_swab32(x) : __builtin_bswap32(x))
76 #define ntohs(x) htons(x)
77 #define ntohl(x) htonl(x)
78
is_received_skb(struct __sk_buff * skb)79 static inline __always_inline __unused bool is_received_skb(struct __sk_buff* skb) {
80 return skb->pkt_type == PACKET_HOST || skb->pkt_type == PACKET_BROADCAST ||
81 skb->pkt_type == PACKET_MULTICAST;
82 }
83
84 // try to make the first 'len' header bytes readable/writable via direct packet access
85 // (note: AFAIK there is no way to ask for only direct packet read without also getting write)
try_make_writable(struct __sk_buff * skb,int len)86 static inline __always_inline void try_make_writable(struct __sk_buff* skb, int len) {
87 if (len > skb->len) len = skb->len;
88 if (skb->data_end - skb->data < len) bpf_skb_pull_data(skb, len);
89 }
90
91 struct egress_bool { bool egress; };
92 #define INGRESS ((struct egress_bool){ .egress = false })
93 #define EGRESS ((struct egress_bool){ .egress = true })
94
95 struct stream_bool { bool down; };
96 #define UPSTREAM ((struct stream_bool){ .down = false })
97 #define DOWNSTREAM ((struct stream_bool){ .down = true })
98
99 struct rawip_bool { bool rawip; };
100 #define ETHER ((struct rawip_bool){ .rawip = false })
101 #define RAWIP ((struct rawip_bool){ .rawip = true })
102
103 struct updatetime_bool { bool updatetime; };
104 #define NO_UPDATETIME ((struct updatetime_bool){ .updatetime = false })
105 #define UPDATETIME ((struct updatetime_bool){ .updatetime = true })
106