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-rw-r--r--net/ipv4/bpf_tcp_ca.c252
1 files changed, 252 insertions, 0 deletions
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
new file mode 100644
index 000000000000..574972bc7299
--- /dev/null
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+
+#include <linux/types.h>
+#include <linux/bpf_verifier.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <net/tcp.h>
+
+static u32 optional_ops[] = {
+ offsetof(struct tcp_congestion_ops, init),
+ offsetof(struct tcp_congestion_ops, release),
+ offsetof(struct tcp_congestion_ops, set_state),
+ offsetof(struct tcp_congestion_ops, cwnd_event),
+ offsetof(struct tcp_congestion_ops, in_ack_event),
+ offsetof(struct tcp_congestion_ops, pkts_acked),
+ offsetof(struct tcp_congestion_ops, min_tso_segs),
+ offsetof(struct tcp_congestion_ops, sndbuf_expand),
+ offsetof(struct tcp_congestion_ops, cong_control),
+};
+
+static u32 unsupported_ops[] = {
+ offsetof(struct tcp_congestion_ops, get_info),
+};
+
+static const struct btf_type *tcp_sock_type;
+static u32 tcp_sock_id, sock_id;
+
+static int bpf_tcp_ca_init(struct btf *btf)
+{
+ s32 type_id;
+
+ type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+ sock_id = type_id;
+
+ type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+ tcp_sock_id = type_id;
+ tcp_sock_type = btf_type_by_id(btf, tcp_sock_id);
+
+ return 0;
+}
+
+static bool is_optional(u32 member_offset)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(optional_ops); i++) {
+ if (member_offset == optional_ops[i])
+ return true;
+ }
+
+ return false;
+}
+
+static bool is_unsupported(u32 member_offset)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) {
+ if (member_offset == unsupported_ops[i])
+ return true;
+ }
+
+ return false;
+}
+
+extern struct btf *btf_vmlinux;
+
+static bool bpf_tcp_ca_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
+ return false;
+ if (type != BPF_READ)
+ return false;
+ if (off % size != 0)
+ return false;
+
+ if (!btf_ctx_access(off, size, type, prog, info))
+ return false;
+
+ if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id)
+ /* promote it to tcp_sock */
+ info->btf_id = tcp_sock_id;
+
+ return true;
+}
+
+static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log,
+ const struct btf_type *t, int off,
+ int size, enum bpf_access_type atype,
+ u32 *next_btf_id)
+{
+ size_t end;
+
+ if (atype == BPF_READ)
+ return btf_struct_access(log, t, off, size, atype, next_btf_id);
+
+ if (t != tcp_sock_type) {
+ bpf_log(log, "only read is supported\n");
+ return -EACCES;
+ }
+
+ switch (off) {
+ case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv):
+ end = offsetofend(struct inet_connection_sock, icsk_ca_priv);
+ break;
+ case offsetof(struct inet_connection_sock, icsk_ack.pending):
+ end = offsetofend(struct inet_connection_sock,
+ icsk_ack.pending);
+ break;
+ case offsetof(struct tcp_sock, snd_cwnd):
+ end = offsetofend(struct tcp_sock, snd_cwnd);
+ break;
+ case offsetof(struct tcp_sock, snd_cwnd_cnt):
+ end = offsetofend(struct tcp_sock, snd_cwnd_cnt);
+ break;
+ case offsetof(struct tcp_sock, snd_ssthresh):
+ end = offsetofend(struct tcp_sock, snd_ssthresh);
+ break;
+ case offsetof(struct tcp_sock, ecn_flags):
+ end = offsetofend(struct tcp_sock, ecn_flags);
+ break;
+ default:
+ bpf_log(log, "no write support to tcp_sock at off %d\n", off);
+ return -EACCES;
+ }
+
+ if (off + size > end) {
+ bpf_log(log,
+ "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n",
+ off, size, end);
+ return -EACCES;
+ }
+
+ return NOT_INIT;
+}
+
+BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt)
+{
+ /* bpf_tcp_ca prog cannot have NULL tp */
+ __tcp_send_ack((struct sock *)tp, rcv_nxt);
+ return 0;
+}
+
+static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
+ .func = bpf_tcp_send_ack,
+ .gpl_only = false,
+ /* In case we want to report error later */
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg2_type = ARG_ANYTHING,
+ .btf_id = &tcp_sock_id,
+};
+
+static const struct bpf_func_proto *
+bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
+ const struct bpf_prog *prog)
+{
+ switch (func_id) {
+ case BPF_FUNC_tcp_send_ack:
+ return &bpf_tcp_send_ack_proto;
+ default:
+ return bpf_base_func_proto(func_id);
+ }
+}
+
+static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
+ .get_func_proto = bpf_tcp_ca_get_func_proto,
+ .is_valid_access = bpf_tcp_ca_is_valid_access,
+ .btf_struct_access = bpf_tcp_ca_btf_struct_access,
+};
+
+static int bpf_tcp_ca_init_member(const struct btf_type *t,
+ const struct btf_member *member,
+ void *kdata, const void *udata)
+{
+ const struct tcp_congestion_ops *utcp_ca;
+ struct tcp_congestion_ops *tcp_ca;
+ size_t tcp_ca_name_len;
+ int prog_fd;
+ u32 moff;
+
+ utcp_ca = (const struct tcp_congestion_ops *)udata;
+ tcp_ca = (struct tcp_congestion_ops *)kdata;
+
+ moff = btf_member_bit_offset(t, member) / 8;
+ switch (moff) {
+ case offsetof(struct tcp_congestion_ops, flags):
+ if (utcp_ca->flags & ~TCP_CONG_MASK)
+ return -EINVAL;
+ tcp_ca->flags = utcp_ca->flags;
+ return 1;
+ case offsetof(struct tcp_congestion_ops, name):
+ tcp_ca_name_len = strnlen(utcp_ca->name, sizeof(utcp_ca->name));
+ if (!tcp_ca_name_len ||
+ tcp_ca_name_len == sizeof(utcp_ca->name))
+ return -EINVAL;
+ if (tcp_ca_find(utcp_ca->name))
+ return -EEXIST;
+ memcpy(tcp_ca->name, utcp_ca->name, sizeof(tcp_ca->name));
+ return 1;
+ }
+
+ if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL))
+ return 0;
+
+ /* Ensure bpf_prog is provided for compulsory func ptr */
+ prog_fd = (int)(*(unsigned long *)(udata + moff));
+ if (!prog_fd && !is_optional(moff) && !is_unsupported(moff))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int bpf_tcp_ca_check_member(const struct btf_type *t,
+ const struct btf_member *member)
+{
+ if (is_unsupported(btf_member_bit_offset(t, member) / 8))
+ return -ENOTSUPP;
+ return 0;
+}
+
+static int bpf_tcp_ca_reg(void *kdata)
+{
+ return tcp_register_congestion_control(kdata);
+}
+
+static void bpf_tcp_ca_unreg(void *kdata)
+{
+ tcp_unregister_congestion_control(kdata);
+}
+
+/* Avoid sparse warning. It is only used in bpf_struct_ops.c. */
+extern struct bpf_struct_ops bpf_tcp_congestion_ops;
+
+struct bpf_struct_ops bpf_tcp_congestion_ops = {
+ .verifier_ops = &bpf_tcp_ca_verifier_ops,
+ .reg = bpf_tcp_ca_reg,
+ .unreg = bpf_tcp_ca_unreg,
+ .check_member = bpf_tcp_ca_check_member,
+ .init_member = bpf_tcp_ca_init_member,
+ .init = bpf_tcp_ca_init,
+ .name = "tcp_congestion_ops",
+};