284 lines
7.5 KiB
C
284 lines
7.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/bpf_verifier.h>
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#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/btf_ids.h>
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#include <linux/filter.h>
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#include <net/tcp.h>
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#include <net/bpf_sk_storage.h>
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/* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */
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extern struct bpf_struct_ops bpf_tcp_congestion_ops;
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static u32 unsupported_ops[] = {
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offsetof(struct tcp_congestion_ops, get_info),
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};
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static const struct btf_type *tcp_sock_type;
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static u32 tcp_sock_id, sock_id;
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static int bpf_tcp_ca_init(struct btf *btf)
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{
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s32 type_id;
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type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT);
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if (type_id < 0)
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return -EINVAL;
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sock_id = type_id;
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type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT);
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if (type_id < 0)
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return -EINVAL;
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tcp_sock_id = type_id;
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tcp_sock_type = btf_type_by_id(btf, tcp_sock_id);
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return 0;
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}
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static bool is_unsupported(u32 member_offset)
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{
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) {
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if (member_offset == unsupported_ops[i])
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return true;
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}
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return false;
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}
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extern struct btf *btf_vmlinux;
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static bool bpf_tcp_ca_is_valid_access(int off, int size,
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enum bpf_access_type type,
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const struct bpf_prog *prog,
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struct bpf_insn_access_aux *info)
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{
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if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info))
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return false;
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if (base_type(info->reg_type) == PTR_TO_BTF_ID &&
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!bpf_type_has_unsafe_modifiers(info->reg_type) &&
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info->btf_id == sock_id)
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/* promote it to tcp_sock */
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info->btf_id = tcp_sock_id;
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return true;
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}
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static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log,
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const struct bpf_reg_state *reg,
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int off, int size, enum bpf_access_type atype,
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u32 *next_btf_id, enum bpf_type_flag *flag)
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{
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const struct btf_type *t;
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size_t end;
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if (atype == BPF_READ)
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return btf_struct_access(log, reg, off, size, atype, next_btf_id, flag);
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t = btf_type_by_id(reg->btf, reg->btf_id);
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if (t != tcp_sock_type) {
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bpf_log(log, "only read is supported\n");
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return -EACCES;
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}
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switch (off) {
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case offsetof(struct sock, sk_pacing_rate):
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end = offsetofend(struct sock, sk_pacing_rate);
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break;
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case offsetof(struct sock, sk_pacing_status):
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end = offsetofend(struct sock, sk_pacing_status);
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break;
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case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv):
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end = offsetofend(struct inet_connection_sock, icsk_ca_priv);
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break;
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case offsetof(struct inet_connection_sock, icsk_ack.pending):
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end = offsetofend(struct inet_connection_sock,
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icsk_ack.pending);
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break;
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case offsetof(struct tcp_sock, snd_cwnd):
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end = offsetofend(struct tcp_sock, snd_cwnd);
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break;
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case offsetof(struct tcp_sock, snd_cwnd_cnt):
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end = offsetofend(struct tcp_sock, snd_cwnd_cnt);
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break;
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case offsetof(struct tcp_sock, snd_ssthresh):
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end = offsetofend(struct tcp_sock, snd_ssthresh);
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break;
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case offsetof(struct tcp_sock, ecn_flags):
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end = offsetofend(struct tcp_sock, ecn_flags);
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break;
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default:
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bpf_log(log, "no write support to tcp_sock at off %d\n", off);
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return -EACCES;
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}
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if (off + size > end) {
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bpf_log(log,
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"write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n",
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off, size, end);
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return -EACCES;
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}
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return 0;
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}
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BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt)
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{
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/* bpf_tcp_ca prog cannot have NULL tp */
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__tcp_send_ack((struct sock *)tp, rcv_nxt);
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return 0;
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}
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static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
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.func = bpf_tcp_send_ack,
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.gpl_only = false,
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/* In case we want to report error later */
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_BTF_ID,
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.arg1_btf_id = &tcp_sock_id,
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.arg2_type = ARG_ANYTHING,
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};
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static u32 prog_ops_moff(const struct bpf_prog *prog)
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{
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const struct btf_member *m;
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const struct btf_type *t;
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u32 midx;
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midx = prog->expected_attach_type;
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t = bpf_tcp_congestion_ops.type;
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m = &btf_type_member(t)[midx];
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return __btf_member_bit_offset(t, m) / 8;
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}
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static const struct bpf_func_proto *
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bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
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const struct bpf_prog *prog)
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{
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switch (func_id) {
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case BPF_FUNC_tcp_send_ack:
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return &bpf_tcp_send_ack_proto;
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case BPF_FUNC_sk_storage_get:
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return &bpf_sk_storage_get_proto;
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case BPF_FUNC_sk_storage_delete:
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return &bpf_sk_storage_delete_proto;
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case BPF_FUNC_setsockopt:
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/* Does not allow release() to call setsockopt.
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* release() is called when the current bpf-tcp-cc
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* is retiring. It is not allowed to call
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* setsockopt() to make further changes which
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* may potentially allocate new resources.
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*/
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if (prog_ops_moff(prog) !=
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offsetof(struct tcp_congestion_ops, release))
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return &bpf_sk_setsockopt_proto;
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return NULL;
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case BPF_FUNC_getsockopt:
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/* Since get/setsockopt is usually expected to
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* be available together, disable getsockopt for
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* release also to avoid usage surprise.
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* The bpf-tcp-cc already has a more powerful way
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* to read tcp_sock from the PTR_TO_BTF_ID.
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*/
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if (prog_ops_moff(prog) !=
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offsetof(struct tcp_congestion_ops, release))
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return &bpf_sk_getsockopt_proto;
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return NULL;
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case BPF_FUNC_ktime_get_coarse_ns:
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return &bpf_ktime_get_coarse_ns_proto;
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default:
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return bpf_base_func_proto(func_id);
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}
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}
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BTF_SET8_START(bpf_tcp_ca_check_kfunc_ids)
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BTF_ID_FLAGS(func, tcp_reno_ssthresh)
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BTF_ID_FLAGS(func, tcp_reno_cong_avoid)
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BTF_ID_FLAGS(func, tcp_reno_undo_cwnd)
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BTF_ID_FLAGS(func, tcp_slow_start)
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BTF_ID_FLAGS(func, tcp_cong_avoid_ai)
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BTF_SET8_END(bpf_tcp_ca_check_kfunc_ids)
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static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &bpf_tcp_ca_check_kfunc_ids,
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};
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static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
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.get_func_proto = bpf_tcp_ca_get_func_proto,
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.is_valid_access = bpf_tcp_ca_is_valid_access,
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.btf_struct_access = bpf_tcp_ca_btf_struct_access,
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};
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static int bpf_tcp_ca_init_member(const struct btf_type *t,
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const struct btf_member *member,
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void *kdata, const void *udata)
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{
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const struct tcp_congestion_ops *utcp_ca;
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struct tcp_congestion_ops *tcp_ca;
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u32 moff;
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utcp_ca = (const struct tcp_congestion_ops *)udata;
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tcp_ca = (struct tcp_congestion_ops *)kdata;
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moff = __btf_member_bit_offset(t, member) / 8;
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switch (moff) {
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case offsetof(struct tcp_congestion_ops, flags):
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if (utcp_ca->flags & ~TCP_CONG_MASK)
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return -EINVAL;
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tcp_ca->flags = utcp_ca->flags;
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return 1;
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case offsetof(struct tcp_congestion_ops, name):
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if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name,
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sizeof(tcp_ca->name)) <= 0)
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return -EINVAL;
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if (tcp_ca_find(utcp_ca->name))
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return -EEXIST;
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return 1;
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}
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return 0;
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}
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static int bpf_tcp_ca_check_member(const struct btf_type *t,
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const struct btf_member *member,
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const struct bpf_prog *prog)
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{
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if (is_unsupported(__btf_member_bit_offset(t, member) / 8))
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return -ENOTSUPP;
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return 0;
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}
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static int bpf_tcp_ca_reg(void *kdata)
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{
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return tcp_register_congestion_control(kdata);
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}
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static void bpf_tcp_ca_unreg(void *kdata)
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{
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tcp_unregister_congestion_control(kdata);
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}
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struct bpf_struct_ops bpf_tcp_congestion_ops = {
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.verifier_ops = &bpf_tcp_ca_verifier_ops,
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.reg = bpf_tcp_ca_reg,
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.unreg = bpf_tcp_ca_unreg,
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.check_member = bpf_tcp_ca_check_member,
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.init_member = bpf_tcp_ca_init_member,
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.init = bpf_tcp_ca_init,
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.name = "tcp_congestion_ops",
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};
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static int __init bpf_tcp_ca_kfunc_init(void)
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{
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return register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set);
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}
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late_initcall(bpf_tcp_ca_kfunc_init);
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