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0baf26b0 MKL |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2019 Facebook */ | |
3 | ||
4 | #include <linux/types.h> | |
5 | #include <linux/bpf_verifier.h> | |
6 | #include <linux/bpf.h> | |
7 | #include <linux/btf.h> | |
8 | #include <linux/filter.h> | |
9 | #include <net/tcp.h> | |
ab14fd4e | 10 | #include <net/bpf_sk_storage.h> |
0baf26b0 MKL |
11 | |
12 | static u32 optional_ops[] = { | |
13 | offsetof(struct tcp_congestion_ops, init), | |
14 | offsetof(struct tcp_congestion_ops, release), | |
15 | offsetof(struct tcp_congestion_ops, set_state), | |
16 | offsetof(struct tcp_congestion_ops, cwnd_event), | |
17 | offsetof(struct tcp_congestion_ops, in_ack_event), | |
18 | offsetof(struct tcp_congestion_ops, pkts_acked), | |
19 | offsetof(struct tcp_congestion_ops, min_tso_segs), | |
20 | offsetof(struct tcp_congestion_ops, sndbuf_expand), | |
21 | offsetof(struct tcp_congestion_ops, cong_control), | |
22 | }; | |
23 | ||
24 | static u32 unsupported_ops[] = { | |
25 | offsetof(struct tcp_congestion_ops, get_info), | |
26 | }; | |
27 | ||
28 | static const struct btf_type *tcp_sock_type; | |
29 | static u32 tcp_sock_id, sock_id; | |
30 | ||
31 | static int bpf_tcp_ca_init(struct btf *btf) | |
32 | { | |
33 | s32 type_id; | |
34 | ||
35 | type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); | |
36 | if (type_id < 0) | |
37 | return -EINVAL; | |
38 | sock_id = type_id; | |
39 | ||
40 | type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); | |
41 | if (type_id < 0) | |
42 | return -EINVAL; | |
43 | tcp_sock_id = type_id; | |
44 | tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); | |
45 | ||
46 | return 0; | |
47 | } | |
48 | ||
49 | static bool is_optional(u32 member_offset) | |
50 | { | |
51 | unsigned int i; | |
52 | ||
53 | for (i = 0; i < ARRAY_SIZE(optional_ops); i++) { | |
54 | if (member_offset == optional_ops[i]) | |
55 | return true; | |
56 | } | |
57 | ||
58 | return false; | |
59 | } | |
60 | ||
61 | static bool is_unsupported(u32 member_offset) | |
62 | { | |
63 | unsigned int i; | |
64 | ||
65 | for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { | |
66 | if (member_offset == unsupported_ops[i]) | |
67 | return true; | |
68 | } | |
69 | ||
70 | return false; | |
71 | } | |
72 | ||
73 | extern struct btf *btf_vmlinux; | |
74 | ||
75 | static bool bpf_tcp_ca_is_valid_access(int off, int size, | |
76 | enum bpf_access_type type, | |
77 | const struct bpf_prog *prog, | |
78 | struct bpf_insn_access_aux *info) | |
79 | { | |
80 | if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) | |
81 | return false; | |
82 | if (type != BPF_READ) | |
83 | return false; | |
84 | if (off % size != 0) | |
85 | return false; | |
86 | ||
87 | if (!btf_ctx_access(off, size, type, prog, info)) | |
88 | return false; | |
89 | ||
90 | if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) | |
91 | /* promote it to tcp_sock */ | |
92 | info->btf_id = tcp_sock_id; | |
93 | ||
94 | return true; | |
95 | } | |
96 | ||
97 | static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, | |
22dc4a0f | 98 | const struct btf *btf, |
0baf26b0 MKL |
99 | const struct btf_type *t, int off, |
100 | int size, enum bpf_access_type atype, | |
101 | u32 *next_btf_id) | |
102 | { | |
103 | size_t end; | |
104 | ||
105 | if (atype == BPF_READ) | |
22dc4a0f | 106 | return btf_struct_access(log, btf, t, off, size, atype, next_btf_id); |
0baf26b0 MKL |
107 | |
108 | if (t != tcp_sock_type) { | |
109 | bpf_log(log, "only read is supported\n"); | |
110 | return -EACCES; | |
111 | } | |
112 | ||
113 | switch (off) { | |
114 | case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): | |
115 | end = offsetofend(struct inet_connection_sock, icsk_ca_priv); | |
116 | break; | |
117 | case offsetof(struct inet_connection_sock, icsk_ack.pending): | |
118 | end = offsetofend(struct inet_connection_sock, | |
119 | icsk_ack.pending); | |
120 | break; | |
121 | case offsetof(struct tcp_sock, snd_cwnd): | |
122 | end = offsetofend(struct tcp_sock, snd_cwnd); | |
123 | break; | |
124 | case offsetof(struct tcp_sock, snd_cwnd_cnt): | |
125 | end = offsetofend(struct tcp_sock, snd_cwnd_cnt); | |
126 | break; | |
127 | case offsetof(struct tcp_sock, snd_ssthresh): | |
128 | end = offsetofend(struct tcp_sock, snd_ssthresh); | |
129 | break; | |
130 | case offsetof(struct tcp_sock, ecn_flags): | |
131 | end = offsetofend(struct tcp_sock, ecn_flags); | |
132 | break; | |
133 | default: | |
134 | bpf_log(log, "no write support to tcp_sock at off %d\n", off); | |
135 | return -EACCES; | |
136 | } | |
137 | ||
138 | if (off + size > end) { | |
139 | bpf_log(log, | |
140 | "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", | |
141 | off, size, end); | |
142 | return -EACCES; | |
143 | } | |
144 | ||
145 | return NOT_INIT; | |
146 | } | |
147 | ||
206057fe MKL |
148 | BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) |
149 | { | |
150 | /* bpf_tcp_ca prog cannot have NULL tp */ | |
151 | __tcp_send_ack((struct sock *)tp, rcv_nxt); | |
152 | return 0; | |
153 | } | |
154 | ||
155 | static const struct bpf_func_proto bpf_tcp_send_ack_proto = { | |
156 | .func = bpf_tcp_send_ack, | |
157 | .gpl_only = false, | |
158 | /* In case we want to report error later */ | |
159 | .ret_type = RET_INTEGER, | |
160 | .arg1_type = ARG_PTR_TO_BTF_ID, | |
9436ef6e | 161 | .arg1_btf_id = &tcp_sock_id, |
206057fe | 162 | .arg2_type = ARG_ANYTHING, |
206057fe MKL |
163 | }; |
164 | ||
0baf26b0 MKL |
165 | static const struct bpf_func_proto * |
166 | bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, | |
167 | const struct bpf_prog *prog) | |
168 | { | |
206057fe MKL |
169 | switch (func_id) { |
170 | case BPF_FUNC_tcp_send_ack: | |
171 | return &bpf_tcp_send_ack_proto; | |
ab14fd4e | 172 | case BPF_FUNC_sk_storage_get: |
592a3498 | 173 | return &bpf_sk_storage_get_proto; |
ab14fd4e | 174 | case BPF_FUNC_sk_storage_delete: |
592a3498 | 175 | return &bpf_sk_storage_delete_proto; |
206057fe MKL |
176 | default: |
177 | return bpf_base_func_proto(func_id); | |
178 | } | |
0baf26b0 MKL |
179 | } |
180 | ||
181 | static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { | |
182 | .get_func_proto = bpf_tcp_ca_get_func_proto, | |
183 | .is_valid_access = bpf_tcp_ca_is_valid_access, | |
184 | .btf_struct_access = bpf_tcp_ca_btf_struct_access, | |
185 | }; | |
186 | ||
187 | static int bpf_tcp_ca_init_member(const struct btf_type *t, | |
188 | const struct btf_member *member, | |
189 | void *kdata, const void *udata) | |
190 | { | |
191 | const struct tcp_congestion_ops *utcp_ca; | |
192 | struct tcp_congestion_ops *tcp_ca; | |
0baf26b0 MKL |
193 | int prog_fd; |
194 | u32 moff; | |
195 | ||
196 | utcp_ca = (const struct tcp_congestion_ops *)udata; | |
197 | tcp_ca = (struct tcp_congestion_ops *)kdata; | |
198 | ||
199 | moff = btf_member_bit_offset(t, member) / 8; | |
200 | switch (moff) { | |
201 | case offsetof(struct tcp_congestion_ops, flags): | |
202 | if (utcp_ca->flags & ~TCP_CONG_MASK) | |
203 | return -EINVAL; | |
204 | tcp_ca->flags = utcp_ca->flags; | |
205 | return 1; | |
206 | case offsetof(struct tcp_congestion_ops, name): | |
8e7ae251 MKL |
207 | if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, |
208 | sizeof(tcp_ca->name)) <= 0) | |
0baf26b0 MKL |
209 | return -EINVAL; |
210 | if (tcp_ca_find(utcp_ca->name)) | |
211 | return -EEXIST; | |
0baf26b0 MKL |
212 | return 1; |
213 | } | |
214 | ||
215 | if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) | |
216 | return 0; | |
217 | ||
218 | /* Ensure bpf_prog is provided for compulsory func ptr */ | |
219 | prog_fd = (int)(*(unsigned long *)(udata + moff)); | |
220 | if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) | |
221 | return -EINVAL; | |
222 | ||
223 | return 0; | |
224 | } | |
225 | ||
226 | static int bpf_tcp_ca_check_member(const struct btf_type *t, | |
227 | const struct btf_member *member) | |
228 | { | |
229 | if (is_unsupported(btf_member_bit_offset(t, member) / 8)) | |
230 | return -ENOTSUPP; | |
231 | return 0; | |
232 | } | |
233 | ||
234 | static int bpf_tcp_ca_reg(void *kdata) | |
235 | { | |
236 | return tcp_register_congestion_control(kdata); | |
237 | } | |
238 | ||
239 | static void bpf_tcp_ca_unreg(void *kdata) | |
240 | { | |
241 | tcp_unregister_congestion_control(kdata); | |
242 | } | |
243 | ||
244 | /* Avoid sparse warning. It is only used in bpf_struct_ops.c. */ | |
245 | extern struct bpf_struct_ops bpf_tcp_congestion_ops; | |
246 | ||
247 | struct bpf_struct_ops bpf_tcp_congestion_ops = { | |
248 | .verifier_ops = &bpf_tcp_ca_verifier_ops, | |
249 | .reg = bpf_tcp_ca_reg, | |
250 | .unreg = bpf_tcp_ca_unreg, | |
251 | .check_member = bpf_tcp_ca_check_member, | |
252 | .init_member = bpf_tcp_ca_init_member, | |
253 | .init = bpf_tcp_ca_init, | |
254 | .name = "tcp_congestion_ops", | |
255 | }; |