selftests/bpf: Rewrite test_sock_addr bind bpf into C

I'm planning to extend it in the next patches. It's much easier to
work with C than BPF assembly.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201202172516.3483656-2-sdf@google.com

1 files changed, 71 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/bind4_prog.c b/tools/testing/selftests/bpf/progs/bind4_prog.c
new file mode 100644
index 000000000000..0951302a984a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bind4_prog.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <string.h>
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <sys/socket.h>
+#include <netinet/tcp.h>
+#include <linux/if.h>
+#include <errno.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+#define SERV4_IP		0xc0a801feU /* 192.168.1.254 */
+#define SERV4_PORT		4040
+#define SERV4_REWRITE_IP	0x7f000001U /* 127.0.0.1 */
+#define SERV4_REWRITE_PORT	4444
+
+SEC("cgroup/bind4")
+int bind_v4_prog(struct bpf_sock_addr *ctx)
+{
+	struct bpf_sock *sk;
+	__u32 user_ip4;
+	__u16 user_port;
+
+	sk = ctx->sk;
+	if (!sk)
+		return 0;
+
+	if (sk->family != AF_INET)
+		return 0;
+
+	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
+		return 0;
+
+	if (ctx->user_ip4 != bpf_htonl(SERV4_IP) ||
+	    ctx->user_port != bpf_htons(SERV4_PORT))
+		return 0;
+
+	// u8 narrow loads:
+	user_ip4 = 0;
+	user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0;
+	user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8;
+	user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16;
+	user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24;
+	if (ctx->user_ip4 != user_ip4)
+		return 0;
+
+	user_port = 0;
+	user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
+	user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
+	if (ctx->user_port != user_port)
+		return 0;
+
+	// u16 narrow loads:
+	user_ip4 = 0;
+	user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0;
+	user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16;
+	if (ctx->user_ip4 != user_ip4)
+		return 0;
+
+	ctx->user_ip4 = bpf_htonl(SERV4_REWRITE_IP);
+	ctx->user_port = bpf_htons(SERV4_REWRITE_PORT);
+
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";