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bpf: program to load and attach sock_ops BPF progs

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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>
This commit is contained in:
Lawrence Brakmo 2017-06-30 20:02:41 -07:00 committed by David S. Miller
parent 40304b2a15
commit ae16189efb
2 changed files with 100 additions and 0 deletions
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3
samples/bpf/Makefile
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@ -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

97
samples/bpf/load_sock_ops.c Normal file
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@ -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;
}