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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> | |
10 | ||
11 | static u32 optional_ops[] = { | |
12 | offsetof(struct tcp_congestion_ops, init), | |
13 | offsetof(struct tcp_congestion_ops, release), | |
14 | offsetof(struct tcp_congestion_ops, set_state), | |
15 | offsetof(struct tcp_congestion_ops, cwnd_event), | |
16 | offsetof(struct tcp_congestion_ops, in_ack_event), | |
17 | offsetof(struct tcp_congestion_ops, pkts_acked), | |
18 | offsetof(struct tcp_congestion_ops, min_tso_segs), | |
19 | offsetof(struct tcp_congestion_ops, sndbuf_expand), | |
20 | offsetof(struct tcp_congestion_ops, cong_control), | |
21 | }; | |
22 | ||
23 | static u32 unsupported_ops[] = { | |
24 | offsetof(struct tcp_congestion_ops, get_info), | |
25 | }; | |
26 | ||
27 | static const struct btf_type *tcp_sock_type; | |
28 | static u32 tcp_sock_id, sock_id; | |
29 | ||
30 | static int bpf_tcp_ca_init(struct btf *btf) | |
31 | { | |
32 | s32 type_id; | |
33 | ||
34 | type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); | |
35 | if (type_id < 0) | |
36 | return -EINVAL; | |
37 | sock_id = type_id; | |
38 | ||
39 | type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); | |
40 | if (type_id < 0) | |
41 | return -EINVAL; | |
42 | tcp_sock_id = type_id; | |
43 | tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); | |
44 | ||
45 | return 0; | |
46 | } | |
47 | ||
48 | static bool is_optional(u32 member_offset) | |
49 | { | |
50 | unsigned int i; | |
51 | ||
52 | for (i = 0; i < ARRAY_SIZE(optional_ops); i++) { | |
53 | if (member_offset == optional_ops[i]) | |
54 | return true; | |
55 | } | |
56 | ||
57 | return false; | |
58 | } | |
59 | ||
60 | static bool is_unsupported(u32 member_offset) | |
61 | { | |
62 | unsigned int i; | |
63 | ||
64 | for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { | |
65 | if (member_offset == unsupported_ops[i]) | |
66 | return true; | |
67 | } | |
68 | ||
69 | return false; | |
70 | } | |
71 | ||
72 | extern struct btf *btf_vmlinux; | |
73 | ||
74 | static bool bpf_tcp_ca_is_valid_access(int off, int size, | |
75 | enum bpf_access_type type, | |
76 | const struct bpf_prog *prog, | |
77 | struct bpf_insn_access_aux *info) | |
78 | { | |
79 | if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) | |
80 | return false; | |
81 | if (type != BPF_READ) | |
82 | return false; | |
83 | if (off % size != 0) | |
84 | return false; | |
85 | ||
86 | if (!btf_ctx_access(off, size, type, prog, info)) | |
87 | return false; | |
88 | ||
89 | if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) | |
90 | /* promote it to tcp_sock */ | |
91 | info->btf_id = tcp_sock_id; | |
92 | ||
93 | return true; | |
94 | } | |
95 | ||
96 | static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, | |
97 | const struct btf_type *t, int off, | |
98 | int size, enum bpf_access_type atype, | |
99 | u32 *next_btf_id) | |
100 | { | |
101 | size_t end; | |
102 | ||
103 | if (atype == BPF_READ) | |
104 | return btf_struct_access(log, t, off, size, atype, next_btf_id); | |
105 | ||
106 | if (t != tcp_sock_type) { | |
107 | bpf_log(log, "only read is supported\n"); | |
108 | return -EACCES; | |
109 | } | |
110 | ||
111 | switch (off) { | |
112 | case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): | |
113 | end = offsetofend(struct inet_connection_sock, icsk_ca_priv); | |
114 | break; | |
115 | case offsetof(struct inet_connection_sock, icsk_ack.pending): | |
116 | end = offsetofend(struct inet_connection_sock, | |
117 | icsk_ack.pending); | |
118 | break; | |
119 | case offsetof(struct tcp_sock, snd_cwnd): | |
120 | end = offsetofend(struct tcp_sock, snd_cwnd); | |
121 | break; | |
122 | case offsetof(struct tcp_sock, snd_cwnd_cnt): | |
123 | end = offsetofend(struct tcp_sock, snd_cwnd_cnt); | |
124 | break; | |
125 | case offsetof(struct tcp_sock, snd_ssthresh): | |
126 | end = offsetofend(struct tcp_sock, snd_ssthresh); | |
127 | break; | |
128 | case offsetof(struct tcp_sock, ecn_flags): | |
129 | end = offsetofend(struct tcp_sock, ecn_flags); | |
130 | break; | |
131 | default: | |
132 | bpf_log(log, "no write support to tcp_sock at off %d\n", off); | |
133 | return -EACCES; | |
134 | } | |
135 | ||
136 | if (off + size > end) { | |
137 | bpf_log(log, | |
138 | "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", | |
139 | off, size, end); | |
140 | return -EACCES; | |
141 | } | |
142 | ||
143 | return NOT_INIT; | |
144 | } | |
145 | ||
146 | static const struct bpf_func_proto * | |
147 | bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, | |
148 | const struct bpf_prog *prog) | |
149 | { | |
150 | return bpf_base_func_proto(func_id); | |
151 | } | |
152 | ||
153 | static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { | |
154 | .get_func_proto = bpf_tcp_ca_get_func_proto, | |
155 | .is_valid_access = bpf_tcp_ca_is_valid_access, | |
156 | .btf_struct_access = bpf_tcp_ca_btf_struct_access, | |
157 | }; | |
158 | ||
159 | static int bpf_tcp_ca_init_member(const struct btf_type *t, | |
160 | const struct btf_member *member, | |
161 | void *kdata, const void *udata) | |
162 | { | |
163 | const struct tcp_congestion_ops *utcp_ca; | |
164 | struct tcp_congestion_ops *tcp_ca; | |
165 | size_t tcp_ca_name_len; | |
166 | int prog_fd; | |
167 | u32 moff; | |
168 | ||
169 | utcp_ca = (const struct tcp_congestion_ops *)udata; | |
170 | tcp_ca = (struct tcp_congestion_ops *)kdata; | |
171 | ||
172 | moff = btf_member_bit_offset(t, member) / 8; | |
173 | switch (moff) { | |
174 | case offsetof(struct tcp_congestion_ops, flags): | |
175 | if (utcp_ca->flags & ~TCP_CONG_MASK) | |
176 | return -EINVAL; | |
177 | tcp_ca->flags = utcp_ca->flags; | |
178 | return 1; | |
179 | case offsetof(struct tcp_congestion_ops, name): | |
180 | tcp_ca_name_len = strnlen(utcp_ca->name, sizeof(utcp_ca->name)); | |
181 | if (!tcp_ca_name_len || | |
182 | tcp_ca_name_len == sizeof(utcp_ca->name)) | |
183 | return -EINVAL; | |
184 | if (tcp_ca_find(utcp_ca->name)) | |
185 | return -EEXIST; | |
186 | memcpy(tcp_ca->name, utcp_ca->name, sizeof(tcp_ca->name)); | |
187 | return 1; | |
188 | } | |
189 | ||
190 | if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) | |
191 | return 0; | |
192 | ||
193 | /* Ensure bpf_prog is provided for compulsory func ptr */ | |
194 | prog_fd = (int)(*(unsigned long *)(udata + moff)); | |
195 | if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) | |
196 | return -EINVAL; | |
197 | ||
198 | return 0; | |
199 | } | |
200 | ||
201 | static int bpf_tcp_ca_check_member(const struct btf_type *t, | |
202 | const struct btf_member *member) | |
203 | { | |
204 | if (is_unsupported(btf_member_bit_offset(t, member) / 8)) | |
205 | return -ENOTSUPP; | |
206 | return 0; | |
207 | } | |
208 | ||
209 | static int bpf_tcp_ca_reg(void *kdata) | |
210 | { | |
211 | return tcp_register_congestion_control(kdata); | |
212 | } | |
213 | ||
214 | static void bpf_tcp_ca_unreg(void *kdata) | |
215 | { | |
216 | tcp_unregister_congestion_control(kdata); | |
217 | } | |
218 | ||
219 | /* Avoid sparse warning. It is only used in bpf_struct_ops.c. */ | |
220 | extern struct bpf_struct_ops bpf_tcp_congestion_ops; | |
221 | ||
222 | struct bpf_struct_ops bpf_tcp_congestion_ops = { | |
223 | .verifier_ops = &bpf_tcp_ca_verifier_ops, | |
224 | .reg = bpf_tcp_ca_reg, | |
225 | .unreg = bpf_tcp_ca_unreg, | |
226 | .check_member = bpf_tcp_ca_check_member, | |
227 | .init_member = bpf_tcp_ca_init_member, | |
228 | .init = bpf_tcp_ca_init, | |
229 | .name = "tcp_congestion_ops", | |
230 | }; |