bpf: selftests: Tcp header options

This patch adds tests for the new bpf tcp header option feature.

test_tcp_hdr_options.c:
- It tests header option writing and parsing in 3WHS: regular
  connection establishment, fastopen, and syncookie.
- In syncookie, the passive side's bpf prog is asking the active side
  to resend its bpf header option by specifying a RESEND bit in the
  outgoing SYNACK. handle_active_estab() and write_nodata_opt() has
  some details.
- handle_passive_estab() has comments on fastopen.
- It also has test for header writing and parsing in FIN packet.
- Most of the tests is writing an experimental option 254 with magic 0xeB9F.
- The no_exprm_estab() also tests writing a regular TCP option
  without any magic.

test_misc_tcp_options.c:
- It is an one directional test.  Active side writes option and
  passive side parses option.  The focus is to exercise
  the new helpers and API.
- Testing the new helper: bpf_load_hdr_opt() and bpf_store_hdr_opt().
- Testing the bpf_getsockopt(TCP_BPF_SYN).
- Negative tests for the above helpers.
- Testing the sock_ops->skb_data.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190117.2886749-1-kafai@fb.com

1 files changed, 151 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/test_tcp_hdr_options.h b/tools/testing/selftests/bpf/test_tcp_hdr_options.h
new file mode 100644
index 000000000000..78a8cf9eab42
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_tcp_hdr_options.h
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2020 Facebook */
+
+#ifndef _TEST_TCP_HDR_OPTIONS_H
+#define _TEST_TCP_HDR_OPTIONS_H
+
+struct bpf_test_option {
+	__u8 flags;
+	__u8 max_delack_ms;
+	__u8 rand;
+} __attribute__((packed));
+
+enum {
+	OPTION_RESEND,
+	OPTION_MAX_DELACK_MS,
+	OPTION_RAND,
+	__NR_OPTION_FLAGS,
+};
+
+#define OPTION_F_RESEND		(1 << OPTION_RESEND)
+#define OPTION_F_MAX_DELACK_MS	(1 << OPTION_MAX_DELACK_MS)
+#define OPTION_F_RAND		(1 << OPTION_RAND)
+#define OPTION_MASK		((1 << __NR_OPTION_FLAGS) - 1)
+
+#define TEST_OPTION_FLAGS(flags, option) (1 & ((flags) >> (option)))
+#define SET_OPTION_FLAGS(flags, option)	((flags) |= (1 << (option)))
+
+/* Store in bpf_sk_storage */
+struct hdr_stg {
+	bool active;
+	bool resend_syn; /* active side only */
+	bool syncookie;  /* passive side only */
+	bool fastopen;	/* passive side only */
+};
+
+struct linum_err {
+	unsigned int linum;
+	int err;
+};
+
+#define TCPHDR_FIN 0x01
+#define TCPHDR_SYN 0x02
+#define TCPHDR_RST 0x04
+#define TCPHDR_PSH 0x08
+#define TCPHDR_ACK 0x10
+#define TCPHDR_URG 0x20
+#define TCPHDR_ECE 0x40
+#define TCPHDR_CWR 0x80
+#define TCPHDR_SYNACK (TCPHDR_SYN | TCPHDR_ACK)
+
+#define TCPOPT_EOL		0
+#define TCPOPT_NOP		1
+#define TCPOPT_WINDOW		3
+#define TCPOPT_EXP		254
+
+#define TCP_BPF_EXPOPT_BASE_LEN 4
+#define MAX_TCP_HDR_LEN		60
+#define MAX_TCP_OPTION_SPACE	40
+
+#ifdef BPF_PROG_TEST_TCP_HDR_OPTIONS
+
+#define CG_OK	1
+#define CG_ERR	0
+
+#ifndef SOL_TCP
+#define SOL_TCP 6
+#endif
+
+struct tcp_exprm_opt {
+	__u8 kind;
+	__u8 len;
+	__u16 magic;
+	union {
+		__u8 data[4];
+		__u32 data32;
+	};
+} __attribute__((packed));
+
+struct tcp_opt {
+	__u8 kind;
+	__u8 len;
+	union {
+		__u8 data[4];
+		__u32 data32;
+	};
+} __attribute__((packed));
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 2);
+	__type(key, int);
+	__type(value, struct linum_err);
+} lport_linum_map SEC(".maps");
+
+static inline unsigned int tcp_hdrlen(const struct tcphdr *th)
+{
+	return th->doff << 2;
+}
+
+static inline __u8 skops_tcp_flags(const struct bpf_sock_ops *skops)
+{
+	return skops->skb_tcp_flags;
+}
+
+static inline void clear_hdr_cb_flags(struct bpf_sock_ops *skops)
+{
+	bpf_sock_ops_cb_flags_set(skops,
+				  skops->bpf_sock_ops_cb_flags &
+				  ~(BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG |
+				    BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG));
+}
+
+static inline void set_hdr_cb_flags(struct bpf_sock_ops *skops)
+{
+	bpf_sock_ops_cb_flags_set(skops,
+				  skops->bpf_sock_ops_cb_flags |
+				  BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG |
+				  BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG);
+}
+static inline void
+clear_parse_all_hdr_cb_flags(struct bpf_sock_ops *skops)
+{
+	bpf_sock_ops_cb_flags_set(skops,
+				  skops->bpf_sock_ops_cb_flags &
+				  ~BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG);
+}
+
+static inline void
+set_parse_all_hdr_cb_flags(struct bpf_sock_ops *skops)
+{
+	bpf_sock_ops_cb_flags_set(skops,
+				  skops->bpf_sock_ops_cb_flags |
+				  BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG);
+}
+
+#define RET_CG_ERR(__err) ({			\
+	struct linum_err __linum_err;		\
+	int __lport;				\
+						\
+	__linum_err.linum = __LINE__;		\
+	__linum_err.err = __err;		\
+	__lport = skops->local_port;		\
+	bpf_map_update_elem(&lport_linum_map, &__lport, &__linum_err, BPF_NOEXIST); \
+	clear_hdr_cb_flags(skops);					\
+	clear_parse_all_hdr_cb_flags(skops);				\
+	return CG_ERR;							\
+})
+
+#endif /* BPF_PROG_TEST_TCP_HDR_OPTIONS */
+
+#endif /* _TEST_TCP_HDR_OPTIONS_H */