bpf: program to load and attach sock_ops BPF progs

The program load_sock_ops can be used to load sock_ops bpf programs and
to attach it to an existing (v2) cgroup. It can also be used to detach
sock_ops programs.

Examples:
    load_sock_ops [-l] <cg-path> <prog filename>
	Load and attaches a sock_ops program at the specified cgroup.
	If "-l" is used, the program will continue to run to output the
	BPF log buffer.
	If the specified filename does not end in ".o", it appends
	"_kern.o" to the name.

    load_sock_ops -r <cg-path>
	Detaches the currently attached sock_ops program from the
	specified cgroup.

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index e7ec9b8..015589b 100644 (file)
--- 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 += load_sock_ops
 
 # 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
+load_sock_ops-objs := bpf_load.o $(LIBBPF) load_sock_ops.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_load_sock_ops += -lelf
 HOSTLOADLIBES_test_probe_write_user += -lelf
 HOSTLOADLIBES_trace_output += -lelf -lrt
 HOSTLOADLIBES_lathist += -lelf

diff --git a/samples/bpf/load_sock_ops.c b/samples/bpf/load_sock_ops.c
new file mode 100644 (file)
index 0000000..e5da6cf
--- /dev/null
+++ b/samples/bpf/load_sock_ops.c
@@ -0,0 +1,97 @@
+/* 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 <fcntl.h>
+#include <linux/unistd.h>
+
+static void usage(char *pname)
+{
+       printf("USAGE:\n  %s [-l] <cg-path> <prog filename>\n", pname);
+       printf("\tLoad and attach a sock_ops program to the specified "
+              "cgroup\n");
+       printf("\tIf \"-l\" is used, the program will continue to run\n");
+       printf("\tprinting the BPF log buffer\n");
+       printf("\tIf the specified filename does not end in \".o\", it\n");
+       printf("\tappends \"_kern.o\" to the name\n");
+       printf("\n");
+       printf("  %s -r <cg-path>\n", pname);
+       printf("\tDetaches the currently attached sock_ops program\n");
+       printf("\tfrom the specified cgroup\n");
+       printf("\n");
+       exit(1);
+}
+
+int main(int argc, char **argv)
+{
+       int logFlag = 0;
+       int error = 0;
+       char *cg_path;
+       char fn[500];
+       char *prog;
+       int cg_fd;
+
+       if (argc < 3)
+               usage(argv[0]);
+
+       if (!strcmp(argv[1], "-r")) {
+               cg_path = argv[2];
+               cg_fd = open(cg_path, O_DIRECTORY, O_RDONLY);
+               error = bpf_prog_detach(cg_fd, BPF_CGROUP_SOCK_OPS);
+               if (error) {
+                       printf("ERROR: bpf_prog_detach: %d (%s)\n",
+                              error, strerror(errno));
+                       return 2;
+               }
+               return 0;
+       } else if (!strcmp(argv[1], "-h")) {
+               usage(argv[0]);
+       } else if (!strcmp(argv[1], "-l")) {
+               logFlag = 1;
+               if (argc < 4)
+                       usage(argv[0]);
+       }
+
+       prog = argv[argc - 1];
+       cg_path = argv[argc - 2];
+       if (strlen(prog) > 480) {
+               fprintf(stderr, "ERROR: program name too long (> 480 chars)\n");
+               return 3;
+       }
+       cg_fd = open(cg_path, O_DIRECTORY, O_RDONLY);
+
+       if (!strcmp(prog + strlen(prog)-2, ".o"))
+               strcpy(fn, prog);
+       else
+               sprintf(fn, "%s_kern.o", prog);
+       if (logFlag)
+               printf("loading bpf file:%s\n", fn);
+       if (load_bpf_file(fn)) {
+               printf("ERROR: load_bpf_file failed for: %s\n", fn);
+               printf("%s", bpf_log_buf);
+               return 4;
+       }
+       if (logFlag)
+               printf("TCP BPF Loaded %s\n", fn);
+
+       error = bpf_prog_attach(prog_fd[0], cg_fd, BPF_CGROUP_SOCK_OPS, 0);
+       if (error) {
+               printf("ERROR: bpf_prog_attach: %d (%s)\n",
+                      error, strerror(errno));
+               return 5;
+       } else if (logFlag) {
+               read_trace_pipe();
+       }
+
+       return error;
+}