This example adds the trace_opensnoop BPF sample. This example program
prints all activities of files being opened for all programs in the
provided cgroupsv2 cgroup and it's descendants in the cgroupv2 hierarchy.
It populate a cgroups arraymap prior to execution in userspace. This means
that the program must be run in the same cgroups namespace as the programs
that are being traced.
Signed-off-by: Sargun Dhillon <sar...@sargun.me>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Daniel Borkmann <dan...@iogearbox.net>
---
samples/bpf/Makefile | 4 +++
samples/bpf/bpf_helpers.h | 2 ++
samples/bpf/trace_opensnoop_kern.c | 35 +++++++++++++++++++
samples/bpf/trace_opensnoop_user.c | 69 ++++++++++++++++++++++++++++++++++++++
4 files changed, 110 insertions(+)
create mode 100644 samples/bpf/trace_opensnoop_kern.c
create mode 100644 samples/bpf/trace_opensnoop_user.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 90ebf7d..d9c37a4 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -24,6 +24,7 @@ hostprogs-y += test_overhead
hostprogs-y += test_cgrp2_array_pin
hostprogs-y += xdp1
hostprogs-y += xdp2
+hostprogs-y += trace_opensnoop
test_verifier-objs := test_verifier.o libbpf.o
test_maps-objs := test_maps.o libbpf.o
@@ -49,6 +50,7 @@ test_cgrp2_array_pin-objs := libbpf.o test_cgrp2_array_pin.o
xdp1-objs := bpf_load.o libbpf.o xdp1_user.o
# reuse xdp1 source intentionally
xdp2-objs := bpf_load.o libbpf.o xdp1_user.o
+trace_opensnoop-objs := bpf_load.o libbpf.o trace_opensnoop_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -74,6 +76,7 @@ always += parse_varlen.o parse_simple.o parse_ldabs.o
always += test_cgrp2_tc_kern.o
always += xdp1_kern.o
always += xdp2_kern.o
+always += trace_opensnoop_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
@@ -97,6 +100,7 @@ HOSTLOADLIBES_map_perf_test += -lelf -lrt
HOSTLOADLIBES_test_overhead += -lelf -lrt
HOSTLOADLIBES_xdp1 += -lelf
HOSTLOADLIBES_xdp2 += -lelf
+HOSTLOADLIBES_trace_opensnoop += -lelf
# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on
cmdline:
# make samples/bpf/ LLC=~/git/llvm/build/bin/llc
CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/bpf_helpers.h b/samples/bpf/bpf_helpers.h
index 217c8d5..d409cbb 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -43,6 +43,8 @@ static int (*bpf_get_stackid)(void *ctx, void *map, int
flags) =
(void *) BPF_FUNC_get_stackid;
static int (*bpf_probe_write_user)(void *dst, void *src, int size) =
(void *) BPF_FUNC_probe_write_user;
+static int (*bpf_current_task_in_cgroup)(void *map, int index) =
+ (void *) BPF_FUNC_current_task_in_cgroup;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions
diff --git a/samples/bpf/trace_opensnoop_kern.c
b/samples/bpf/trace_opensnoop_kern.c
new file mode 100644
index 0000000..dade471
--- /dev/null
+++ b/samples/bpf/trace_opensnoop_kern.c
@@ -0,0 +1,35 @@
+/* Copyright (c) 2016 Sargun Dhillon <sar...@sargun.me>
+ *
+ * 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 <linux/ptrace.h>
+#include <uapi/linux/bpf.h>
+#include <linux/version.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") cgroup_map = {
+ .type = BPF_MAP_TYPE_CGROUP_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u32),
+ .max_entries = 1,
+};
+
+SEC("kprobe/sys_open")
+int bpf_prog1(struct pt_regs *ctx)
+{
+ const char *filename = (char *)PT_REGS_PARM1(ctx);
+ char fmt[] = "Opening file: %s\n";
+
+ if (!bpf_current_task_in_cgroup(&cgroup_map, 0))
+ return 0;
+
+ bpf_trace_printk(fmt, sizeof(fmt), filename);
+
+ return 1;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/samples/bpf/trace_opensnoop_user.c
b/samples/bpf/trace_opensnoop_user.c
new file mode 100644
index 0000000..403664e
--- /dev/null
+++ b/samples/bpf/trace_opensnoop_user.c
@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <assert.h>
+#include <linux/bpf.h>
+#include <unistd.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+#include <sys/socket.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <linux/bpf.h>
+
+static void usage(char **argv)
+{
+ printf("Usage: %s [...]\n", argv[0]);
+ printf("Prints the file opening activity of all processes under a given
cgroupv2 hierarchy.\n");
+ printf(" -v <value> Full path of the cgroup2\n");
+ printf(" -h Display this help\n");
+}
+
+int main(int argc, char **argv)
+{
+ char filename[256];
+ const char *cg2 = NULL;
+ int ret, opt, cg2_fd;
+ int array_index = 0;
+
+ while ((opt = getopt(argc, argv, "v:")) != -1) {
+ switch (opt) {
+ case 'v':
+ cg2 = optarg;
+ break;
+ default:
+ usage(argv);
+ return 1;
+ }
+ }
+
+ if (!cg2) {
+ usage(argv);
+ return 1;
+ }
+
+ cg2_fd = open(cg2, O_RDONLY);
+ if (cg2_fd < 0) {
+ fprintf(stderr, "open(%s,...): %s(%d)\n",
+ cg2, strerror(errno), errno);
+ return 1;
+ }
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ ret = bpf_update_elem(map_fd[0],
+ &array_index,
+ &cg2_fd, BPF_ANY);
+ if (ret) {
+ perror("bpf_update_elem");
+ return 1;
+ }
+
+ read_trace_pipe();
+ return 0;
+}
--
2.7.4
