[PATCH net-next v3 02/15] bpf: program to load sock_ops BPF programs

[Lawrence Brakmo <brakmo@fb.com>]

The program tcp_bpf can be used to remove current global sock_ops program
and to load/replace sock_ops BPF programs. There is also an option to
print the bpf trace buffer (for debugging purposes).

USAGE:
  ./tcp_bpf [-r] [-l] [<pname>]
WHERE:
  -r      remove current loaded sock_ops BPF program
          not needed if loading a new program
  -l      print BPF trace buffer. Used when loading a new program
  <pname> name of BPF sock_ops program to load
          if <pname> does not end in ".o", then "_kern.o" is appended
          example: using tcp_rto will load tcp_rto_kern.o

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
---
 samples/bpf/Makefile  |  3 ++
 samples/bpf/tcp_bpf.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)
 create mode 100644 samples/bpf/tcp_bpf.c

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index a0561dc..ed6bc75 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -36,6 +36,7 @@ hostprogs-y += lwt_len_hist
 hostprogs-y += xdp_tx_iptunnel
 hostprogs-y += test_map_in_map
 hostprogs-y += per_socket_stats_example
+hostprogs-y += tcp_bpf
 
 # Libbpf dependencies
 LIBBPF := ../../tools/lib/bpf/bpf.o
@@ -52,6 +53,7 @@ tracex3-objs := bpf_load.o $(LIBBPF) tracex3_user.o
 tracex4-objs := bpf_load.o $(LIBBPF) tracex4_user.o
 tracex5-objs := bpf_load.o $(LIBBPF) tracex5_user.o
 tracex6-objs := bpf_load.o $(LIBBPF) tracex6_user.o
+tcp_bpf-objs := bpf_load.o $(LIBBPF) tcp_bpf.o
 test_probe_write_user-objs := bpf_load.o $(LIBBPF) test_probe_write_user_user.o
 trace_output-objs := bpf_load.o $(LIBBPF) trace_output_user.o
 lathist-objs := bpf_load.o $(LIBBPF) lathist_user.o
@@ -130,6 +132,7 @@ HOSTLOADLIBES_tracex4 += -lelf -lrt
 HOSTLOADLIBES_tracex5 += -lelf
 HOSTLOADLIBES_tracex6 += -lelf
 HOSTLOADLIBES_test_cgrp2_sock2 += -lelf
+HOSTLOADLIBES_tcp_bpf += -lelf
 HOSTLOADLIBES_test_probe_write_user += -lelf
 HOSTLOADLIBES_trace_output += -lelf -lrt
 HOSTLOADLIBES_lathist += -lelf
diff --git a/samples/bpf/tcp_bpf.c b/samples/bpf/tcp_bpf.c
new file mode 100644
index 0000000..735b8b2
--- /dev/null
+++ b/samples/bpf/tcp_bpf.c
@@ -0,0 +1,86 @@
+/* Copyright (c) 2017 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+#include <unistd.h>
+#include <errno.h>
+#include <linux/unistd.h>
+
+static void usage(char *pname)
+{
+	printf("USAGE:\n  %s [-r] [-l] <pname>\n", pname);
+	printf("WHERE:\n");
+	printf("  -r      remove current loaded socketops BPF program\n");
+	printf("          not needed if loading a new program\n");
+	printf("  -l      print out BPF log buffer\n");
+	printf("  <pname> name of BPF sockeops program to load\n");
+	printf("          if <pname> does not end in \".o\", then \"_kern.o\" "
+	       "is appended\n");
+	printf("          example: using tcp1 will load tcp1_kern.o\n");
+	printf("\n");
+}
+
+int main(int argc, char **argv)
+{
+	//union bpf_attr attr;
+	int k, logFlag = 0;
+	int error = 0;
+	char fn[500];
+
+	if (argc <= 1)
+		usage(argv[0]);
+	for (k = 1; k < argc; k++) {
+		if (!strcmp(argv[k], "-r")) {
+			error = bpf_prog_detach(0, BPF_GLOBAL_SOCK_OPS);
+			if (error) {
+				printf("ERROR: bpf_prog_detach: %d (%s)\n",
+				       error, strerror(errno));
+				error =  1;
+			}
+		} else if (!strcmp(argv[k], "-l")) {
+			logFlag = 1;
+		} else if (!strcmp(argv[k], "-h")) {
+			usage(argv[0]);
+		} else if (argv[k][0] == '-') {
+			printf("Error, unknown flag: %s\n", argv[k]);
+			error = 2;
+		} else if (strlen(argv[k]) > 450) {
+			printf("Error, program name too long %d\n",
+			       (int) strlen(argv[k]));
+			error = 3;
+		} else {
+			if (!strcmp(argv[k]+strlen(argv[k])-2, ".o"))
+				strcpy(fn, argv[k]);
+			else
+				sprintf(fn, "%s_kern.o", argv[k]);
+			if (logFlag)
+				printf("loading bpf file:%s\n", fn);
+			if (load_bpf_file(fn)) {
+				printf("%s", bpf_log_buf);
+				return 1;
+			}
+			if (logFlag) {
+				printf("TCP BPF Loaded %s\n", fn);
+				printf("%s\n", bpf_log_buf);
+			}
+			error = bpf_prog_attach(prog_fd[0], 0,
+						BPF_GLOBAL_SOCK_OPS, 0);
+			if (error) {
+				printf("ERROR: bpf_prog_attach: %d (%s)\n",
+				       error, strerror(errno));
+				error = 4;
+			} else if (logFlag) {
+				read_trace_pipe();
+			}
+		}
+	}
+	return error;
+}
-- 
2.9.3