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/btf_ids.h>
  9#include <linux/filter.h>
 10#include <net/tcp.h>
 11#include <net/bpf_sk_storage.h>
 12
 13static u32 optional_ops[] = {
 14	offsetof(struct tcp_congestion_ops, init),
 15	offsetof(struct tcp_congestion_ops, release),
 16	offsetof(struct tcp_congestion_ops, set_state),
 17	offsetof(struct tcp_congestion_ops, cwnd_event),
 18	offsetof(struct tcp_congestion_ops, in_ack_event),
 19	offsetof(struct tcp_congestion_ops, pkts_acked),
 20	offsetof(struct tcp_congestion_ops, min_tso_segs),
 21	offsetof(struct tcp_congestion_ops, sndbuf_expand),
 22	offsetof(struct tcp_congestion_ops, cong_control),
 23};
 24
 25static u32 unsupported_ops[] = {
 26	offsetof(struct tcp_congestion_ops, get_info),
 27};
 28
 29static const struct btf_type *tcp_sock_type;
 30static u32 tcp_sock_id, sock_id;
 31
 32static int bpf_tcp_ca_init(struct btf *btf)
 33{
 34	s32 type_id;
 35
 36	type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT);
 37	if (type_id < 0)
 38		return -EINVAL;
 39	sock_id = type_id;
 40
 41	type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT);
 42	if (type_id < 0)
 43		return -EINVAL;
 44	tcp_sock_id = type_id;
 45	tcp_sock_type = btf_type_by_id(btf, tcp_sock_id);
 46
 47	return 0;
 48}
 49
 50static bool is_optional(u32 member_offset)
 51{
 52	unsigned int i;
 53
 54	for (i = 0; i < ARRAY_SIZE(optional_ops); i++) {
 55		if (member_offset == optional_ops[i])
 56			return true;
 57	}
 58
 59	return false;
 60}
 61
 62static bool is_unsupported(u32 member_offset)
 63{
 64	unsigned int i;
 65
 66	for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) {
 67		if (member_offset == unsupported_ops[i])
 68			return true;
 69	}
 70
 71	return false;
 72}
 73
 74extern struct btf *btf_vmlinux;
 75
 76static bool bpf_tcp_ca_is_valid_access(int off, int size,
 77				       enum bpf_access_type type,
 78				       const struct bpf_prog *prog,
 79				       struct bpf_insn_access_aux *info)
 80{
 81	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
 82		return false;
 83	if (type != BPF_READ)
 84		return false;
 85	if (off % size != 0)
 86		return false;
 87
 88	if (!btf_ctx_access(off, size, type, prog, info))
 89		return false;
 90
 91	if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id)
 92		/* promote it to tcp_sock */
 93		info->btf_id = tcp_sock_id;
 94
 95	return true;
 96}
 97
 98static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log,
 99					const struct btf *btf,
100					const struct btf_type *t, int off,
101					int size, enum bpf_access_type atype,
102					u32 *next_btf_id)
103{
104	size_t end;
105
106	if (atype == BPF_READ)
107		return btf_struct_access(log, btf, t, off, size, atype, next_btf_id);
108
109	if (t != tcp_sock_type) {
110		bpf_log(log, "only read is supported\n");
111		return -EACCES;
112	}
113
114	switch (off) {
115	case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv):
116		end = offsetofend(struct inet_connection_sock, icsk_ca_priv);
117		break;
118	case offsetof(struct inet_connection_sock, icsk_ack.pending):
119		end = offsetofend(struct inet_connection_sock,
120				  icsk_ack.pending);
121		break;
122	case offsetof(struct tcp_sock, snd_cwnd):
123		end = offsetofend(struct tcp_sock, snd_cwnd);
124		break;
125	case offsetof(struct tcp_sock, snd_cwnd_cnt):
126		end = offsetofend(struct tcp_sock, snd_cwnd_cnt);
127		break;
128	case offsetof(struct tcp_sock, snd_ssthresh):
129		end = offsetofend(struct tcp_sock, snd_ssthresh);
130		break;
131	case offsetof(struct tcp_sock, ecn_flags):
132		end = offsetofend(struct tcp_sock, ecn_flags);
133		break;
134	default:
135		bpf_log(log, "no write support to tcp_sock at off %d\n", off);
136		return -EACCES;
137	}
138
139	if (off + size > end) {
140		bpf_log(log,
141			"write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n",
142			off, size, end);
143		return -EACCES;
144	}
145
146	return NOT_INIT;
147}
148
149BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt)
150{
151	/* bpf_tcp_ca prog cannot have NULL tp */
152	__tcp_send_ack((struct sock *)tp, rcv_nxt);
153	return 0;
154}
155
156static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
157	.func		= bpf_tcp_send_ack,
158	.gpl_only	= false,
159	/* In case we want to report error later */
160	.ret_type	= RET_INTEGER,
161	.arg1_type	= ARG_PTR_TO_BTF_ID,
162	.arg1_btf_id	= &tcp_sock_id,
163	.arg2_type	= ARG_ANYTHING,
164};
165
166static const struct bpf_func_proto *
167bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
168			  const struct bpf_prog *prog)
169{
170	switch (func_id) {
171	case BPF_FUNC_tcp_send_ack:
172		return &bpf_tcp_send_ack_proto;
173	case BPF_FUNC_sk_storage_get:
174		return &bpf_sk_storage_get_proto;
175	case BPF_FUNC_sk_storage_delete:
176		return &bpf_sk_storage_delete_proto;
177	default:
178		return bpf_base_func_proto(func_id);
179	}
180}
181
182BTF_SET_START(bpf_tcp_ca_kfunc_ids)
183BTF_ID(func, tcp_reno_ssthresh)
184BTF_ID(func, tcp_reno_cong_avoid)
185BTF_ID(func, tcp_reno_undo_cwnd)
186BTF_ID(func, tcp_slow_start)
187BTF_ID(func, tcp_cong_avoid_ai)
188#ifdef CONFIG_X86
189#ifdef CONFIG_DYNAMIC_FTRACE
190#if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC)
191BTF_ID(func, cubictcp_init)
192BTF_ID(func, cubictcp_recalc_ssthresh)
193BTF_ID(func, cubictcp_cong_avoid)
194BTF_ID(func, cubictcp_state)
195BTF_ID(func, cubictcp_cwnd_event)
196BTF_ID(func, cubictcp_acked)
197#endif
198#if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP)
199BTF_ID(func, dctcp_init)
200BTF_ID(func, dctcp_update_alpha)
201BTF_ID(func, dctcp_cwnd_event)
202BTF_ID(func, dctcp_ssthresh)
203BTF_ID(func, dctcp_cwnd_undo)
204BTF_ID(func, dctcp_state)
205#endif
206#if IS_BUILTIN(CONFIG_TCP_CONG_BBR)
207BTF_ID(func, bbr_init)
208BTF_ID(func, bbr_main)
209BTF_ID(func, bbr_sndbuf_expand)
210BTF_ID(func, bbr_undo_cwnd)
211BTF_ID(func, bbr_cwnd_event)
212BTF_ID(func, bbr_ssthresh)
213BTF_ID(func, bbr_min_tso_segs)
214BTF_ID(func, bbr_set_state)
215#endif
216#endif  /* CONFIG_DYNAMIC_FTRACE */
217#endif	/* CONFIG_X86 */
218BTF_SET_END(bpf_tcp_ca_kfunc_ids)
219
220static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id)
221{
222	return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id);
223}
224
225static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
226	.get_func_proto		= bpf_tcp_ca_get_func_proto,
227	.is_valid_access	= bpf_tcp_ca_is_valid_access,
228	.btf_struct_access	= bpf_tcp_ca_btf_struct_access,
229	.check_kfunc_call	= bpf_tcp_ca_check_kfunc_call,
230};
231
232static int bpf_tcp_ca_init_member(const struct btf_type *t,
233				  const struct btf_member *member,
234				  void *kdata, const void *udata)
235{
236	const struct tcp_congestion_ops *utcp_ca;
237	struct tcp_congestion_ops *tcp_ca;
238	int prog_fd;
239	u32 moff;
240
241	utcp_ca = (const struct tcp_congestion_ops *)udata;
242	tcp_ca = (struct tcp_congestion_ops *)kdata;
243
244	moff = btf_member_bit_offset(t, member) / 8;
245	switch (moff) {
246	case offsetof(struct tcp_congestion_ops, flags):
247		if (utcp_ca->flags & ~TCP_CONG_MASK)
248			return -EINVAL;
249		tcp_ca->flags = utcp_ca->flags;
250		return 1;
251	case offsetof(struct tcp_congestion_ops, name):
252		if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name,
253				     sizeof(tcp_ca->name)) <= 0)
254			return -EINVAL;
255		if (tcp_ca_find(utcp_ca->name))
256			return -EEXIST;
257		return 1;
258	}
259
260	if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL))
261		return 0;
262
263	/* Ensure bpf_prog is provided for compulsory func ptr */
264	prog_fd = (int)(*(unsigned long *)(udata + moff));
265	if (!prog_fd && !is_optional(moff) && !is_unsupported(moff))
266		return -EINVAL;
267
268	return 0;
269}
270
271static int bpf_tcp_ca_check_member(const struct btf_type *t,
272				   const struct btf_member *member)
273{
274	if (is_unsupported(btf_member_bit_offset(t, member) / 8))
275		return -ENOTSUPP;
276	return 0;
277}
278
279static int bpf_tcp_ca_reg(void *kdata)
280{
281	return tcp_register_congestion_control(kdata);
282}
283
284static void bpf_tcp_ca_unreg(void *kdata)
285{
286	tcp_unregister_congestion_control(kdata);
287}
288
289/* Avoid sparse warning.  It is only used in bpf_struct_ops.c. */
290extern struct bpf_struct_ops bpf_tcp_congestion_ops;
291
292struct bpf_struct_ops bpf_tcp_congestion_ops = {
293	.verifier_ops = &bpf_tcp_ca_verifier_ops,
294	.reg = bpf_tcp_ca_reg,
295	.unreg = bpf_tcp_ca_unreg,
296	.check_member = bpf_tcp_ca_check_member,
297	.init_member = bpf_tcp_ca_init_member,
298	.init = bpf_tcp_ca_init,
299	.name = "tcp_congestion_ops",
300};