1 | /* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch> |
2 | * |
3 | * This program is free software; you can redistribute it and/or |
4 | * modify it under the terms of version 2 of the GNU General Public |
5 | * License as published by the Free Software Foundation. |
6 | * |
7 | * This program is distributed in the hope that it will be useful, but |
8 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
10 | * General Public License for more details. |
11 | */ |
12 | |
13 | #include "vmlinux.h" |
14 | #include "net_shared.h" |
15 | #include <bpf/bpf_helpers.h> |
16 | #include <string.h> |
17 | |
18 | # define printk(fmt, ...) \ |
19 | ({ \ |
20 | char ____fmt[] = fmt; \ |
21 | bpf_trace_printk(____fmt, sizeof(____fmt), \ |
22 | ##__VA_ARGS__); \ |
23 | }) |
24 | |
25 | #define CB_MAGIC 1234 |
26 | |
27 | /* Test: Pass all packets through */ |
28 | SEC("nop" ) |
29 | int do_nop(struct __sk_buff *skb) |
30 | { |
31 | return BPF_OK; |
32 | } |
33 | |
34 | /* Test: Verify context information can be accessed */ |
35 | SEC("test_ctx" ) |
36 | int do_test_ctx(struct __sk_buff *skb) |
37 | { |
38 | skb->cb[0] = CB_MAGIC; |
39 | printk("len %d hash %d protocol %d" , skb->len, skb->hash, |
40 | skb->protocol); |
41 | printk("cb %d ingress_ifindex %d ifindex %d" , skb->cb[0], |
42 | skb->ingress_ifindex, skb->ifindex); |
43 | |
44 | return BPF_OK; |
45 | } |
46 | |
47 | /* Test: Ensure skb->cb[] buffer is cleared */ |
48 | SEC("test_cb" ) |
49 | int do_test_cb(struct __sk_buff *skb) |
50 | { |
51 | printk("cb0: %x cb1: %x cb2: %x" , skb->cb[0], skb->cb[1], |
52 | skb->cb[2]); |
53 | printk("cb3: %x cb4: %x" , skb->cb[3], skb->cb[4]); |
54 | |
55 | return BPF_OK; |
56 | } |
57 | |
58 | /* Test: Verify skb data can be read */ |
59 | SEC("test_data" ) |
60 | int do_test_data(struct __sk_buff *skb) |
61 | { |
62 | void *data = (void *)(long)skb->data; |
63 | void *data_end = (void *)(long)skb->data_end; |
64 | struct iphdr *iph = data; |
65 | |
66 | if (data + sizeof(*iph) > data_end) { |
67 | printk("packet truncated" ); |
68 | return BPF_DROP; |
69 | } |
70 | |
71 | printk("src: %x dst: %x" , iph->saddr, iph->daddr); |
72 | |
73 | return BPF_OK; |
74 | } |
75 | |
76 | #define IP_CSUM_OFF offsetof(struct iphdr, check) |
77 | #define IP_DST_OFF offsetof(struct iphdr, daddr) |
78 | #define IP_SRC_OFF offsetof(struct iphdr, saddr) |
79 | #define IP_PROTO_OFF offsetof(struct iphdr, protocol) |
80 | #define TCP_CSUM_OFF offsetof(struct tcphdr, check) |
81 | #define UDP_CSUM_OFF offsetof(struct udphdr, check) |
82 | #define IS_PSEUDO 0x10 |
83 | |
84 | static inline int rewrite(struct __sk_buff *skb, uint32_t old_ip, |
85 | uint32_t new_ip, int rw_daddr) |
86 | { |
87 | int ret, off = 0, flags = IS_PSEUDO; |
88 | uint8_t proto; |
89 | |
90 | ret = bpf_skb_load_bytes(skb, IP_PROTO_OFF, &proto, 1); |
91 | if (ret < 0) { |
92 | printk("bpf_l4_csum_replace failed: %d" , ret); |
93 | return BPF_DROP; |
94 | } |
95 | |
96 | switch (proto) { |
97 | case IPPROTO_TCP: |
98 | off = TCP_CSUM_OFF; |
99 | break; |
100 | |
101 | case IPPROTO_UDP: |
102 | off = UDP_CSUM_OFF; |
103 | flags |= BPF_F_MARK_MANGLED_0; |
104 | break; |
105 | |
106 | case IPPROTO_ICMPV6: |
107 | off = offsetof(struct icmp6hdr, icmp6_cksum); |
108 | break; |
109 | } |
110 | |
111 | if (off) { |
112 | ret = bpf_l4_csum_replace(skb, off, old_ip, new_ip, |
113 | flags | sizeof(new_ip)); |
114 | if (ret < 0) { |
115 | printk("bpf_l4_csum_replace failed: %d" ); |
116 | return BPF_DROP; |
117 | } |
118 | } |
119 | |
120 | ret = bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip)); |
121 | if (ret < 0) { |
122 | printk("bpf_l3_csum_replace failed: %d" , ret); |
123 | return BPF_DROP; |
124 | } |
125 | |
126 | if (rw_daddr) |
127 | ret = bpf_skb_store_bytes(skb, IP_DST_OFF, &new_ip, sizeof(new_ip), 0); |
128 | else |
129 | ret = bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0); |
130 | |
131 | if (ret < 0) { |
132 | printk("bpf_skb_store_bytes() failed: %d" , ret); |
133 | return BPF_DROP; |
134 | } |
135 | |
136 | return BPF_OK; |
137 | } |
138 | |
139 | /* Test: Verify skb data can be modified */ |
140 | SEC("test_rewrite" ) |
141 | int do_test_rewrite(struct __sk_buff *skb) |
142 | { |
143 | uint32_t old_ip, new_ip = 0x3fea8c0; |
144 | int ret; |
145 | |
146 | ret = bpf_skb_load_bytes(skb, IP_DST_OFF, &old_ip, 4); |
147 | if (ret < 0) { |
148 | printk("bpf_skb_load_bytes failed: %d" , ret); |
149 | return BPF_DROP; |
150 | } |
151 | |
152 | if (old_ip == 0x2fea8c0) { |
153 | printk("out: rewriting from %x to %x" , old_ip, new_ip); |
154 | return rewrite(skb, old_ip, new_ip, 1); |
155 | } |
156 | |
157 | return BPF_OK; |
158 | } |
159 | |
160 | static inline int __do_push_ll_and_redirect(struct __sk_buff *skb) |
161 | { |
162 | uint64_t smac = SRC_MAC, dmac = DST_MAC; |
163 | int ret, ifindex = DST_IFINDEX; |
164 | struct ethhdr ehdr; |
165 | |
166 | ret = bpf_skb_change_head(skb, 14, 0); |
167 | if (ret < 0) { |
168 | printk("skb_change_head() failed: %d" , ret); |
169 | } |
170 | |
171 | ehdr.h_proto = bpf_htons(ETH_P_IP); |
172 | memcpy(dest: &ehdr.h_source, src: &smac, n: 6); |
173 | memcpy(dest: &ehdr.h_dest, src: &dmac, n: 6); |
174 | |
175 | ret = bpf_skb_store_bytes(skb, 0, &ehdr, sizeof(ehdr), 0); |
176 | if (ret < 0) { |
177 | printk("skb_store_bytes() failed: %d" , ret); |
178 | return BPF_DROP; |
179 | } |
180 | |
181 | return bpf_redirect(ifindex, 0); |
182 | } |
183 | |
184 | SEC("push_ll_and_redirect_silent" ) |
185 | int do_push_ll_and_redirect_silent(struct __sk_buff *skb) |
186 | { |
187 | return __do_push_ll_and_redirect(skb); |
188 | } |
189 | |
190 | SEC("push_ll_and_redirect" ) |
191 | int do_push_ll_and_redirect(struct __sk_buff *skb) |
192 | { |
193 | int ret, ifindex = DST_IFINDEX; |
194 | |
195 | ret = __do_push_ll_and_redirect(skb); |
196 | if (ret >= 0) |
197 | printk("redirected to %d" , ifindex); |
198 | |
199 | return ret; |
200 | } |
201 | |
202 | static inline void __fill_garbage(struct __sk_buff *skb) |
203 | { |
204 | uint64_t f = 0xFFFFFFFFFFFFFFFF; |
205 | |
206 | bpf_skb_store_bytes(skb, 0, &f, sizeof(f), 0); |
207 | bpf_skb_store_bytes(skb, 8, &f, sizeof(f), 0); |
208 | bpf_skb_store_bytes(skb, 16, &f, sizeof(f), 0); |
209 | bpf_skb_store_bytes(skb, 24, &f, sizeof(f), 0); |
210 | bpf_skb_store_bytes(skb, 32, &f, sizeof(f), 0); |
211 | bpf_skb_store_bytes(skb, 40, &f, sizeof(f), 0); |
212 | bpf_skb_store_bytes(skb, 48, &f, sizeof(f), 0); |
213 | bpf_skb_store_bytes(skb, 56, &f, sizeof(f), 0); |
214 | bpf_skb_store_bytes(skb, 64, &f, sizeof(f), 0); |
215 | bpf_skb_store_bytes(skb, 72, &f, sizeof(f), 0); |
216 | bpf_skb_store_bytes(skb, 80, &f, sizeof(f), 0); |
217 | bpf_skb_store_bytes(skb, 88, &f, sizeof(f), 0); |
218 | } |
219 | |
220 | SEC("fill_garbage" ) |
221 | int do_fill_garbage(struct __sk_buff *skb) |
222 | { |
223 | __fill_garbage(skb); |
224 | printk("Set initial 96 bytes of header to FF" ); |
225 | return BPF_OK; |
226 | } |
227 | |
228 | SEC("fill_garbage_and_redirect" ) |
229 | int do_fill_garbage_and_redirect(struct __sk_buff *skb) |
230 | { |
231 | int ifindex = DST_IFINDEX; |
232 | __fill_garbage(skb); |
233 | printk("redirected to %d" , ifindex); |
234 | return bpf_redirect(ifindex, 0); |
235 | } |
236 | |
237 | /* Drop all packets */ |
238 | SEC("drop_all" ) |
239 | int do_drop_all(struct __sk_buff *skb) |
240 | { |
241 | printk("dropping with: %d" , BPF_DROP); |
242 | return BPF_DROP; |
243 | } |
244 | |
245 | char _license[] SEC("license" ) = "GPL" ; |
246 | |