This test has a BPF program which writes the last known pid to call the
sync syscall within a given cgroup to a map.
The user mode program creates its own mount namespace, and mounts the
cgroupsv2 hierarchy in there, as on all current test systems
(Ubuntu 16.04, Debian), the cgroupsv2 vfs is unmounted by default.
Once it does this, it proceeds to test.
The test checks for positive and negative condition. It ensures that
when it's part of a given cgroup, its pid is captured in the map,
and that when it leaves the cgroup, this doesn't happen.
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
Cc: Alexei Starovoitov
Cc: Daniel Borkmann
Cc: Tejun Heo
---
samples/bpf/Makefile | 5 +
samples/bpf/bpf_helpers.h | 2 +
samples/bpf/test_current_task_under_cgroup_kern.c | 43 +++
samples/bpf/test_current_task_under_cgroup_user.c | 145 ++
4 files changed, 195 insertions(+)
create mode 100644 samples/bpf/test_current_task_under_cgroup_kern.c
create mode 100644 samples/bpf/test_current_task_under_cgroup_user.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 90ebf7d..eb582c6 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 += test_current_task_under_cgroup
test_verifier-objs := test_verifier.o libbpf.o
test_maps-objs := test_maps.o libbpf.o
@@ -49,6 +50,8 @@ 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
+test_current_task_under_cgroup-objs := bpf_load.o libbpf.o \
+ test_current_task_under_cgroup_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -74,6 +77,7 @@ always += parse_varlen.o parse_simple.o parse_ldabs.o
always += test_cgrp2_tc_kern.o
always += xdp1_kern.o
always += xdp2_kern.o
+always += test_current_task_under_cgroup_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
@@ -97,6 +101,7 @@ HOSTLOADLIBES_map_perf_test += -lelf -lrt
HOSTLOADLIBES_test_overhead += -lelf -lrt
HOSTLOADLIBES_xdp1 += -lelf
HOSTLOADLIBES_xdp2 += -lelf
+HOSTLOADLIBES_test_current_task_under_cgroup += -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 cbc52df..5e4c41e 100644
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -45,6 +45,8 @@ 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_under_cgroup)(void *map, int index) =
+ (void *) BPF_FUNC_current_task_under_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/test_current_task_under_cgroup_kern.c
b/samples/bpf/test_current_task_under_cgroup_kern.c
new file mode 100644
index 000..86b28d7
--- /dev/null
+++ b/samples/bpf/test_current_task_under_cgroup_kern.c
@@ -0,0 +1,43 @@
+/* Copyright (c) 2016 Sargun Dhillon
+ *
+ * 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
+#include
+#include
+#include "bpf_helpers.h"
+#include
+
+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,
+};
+
+struct bpf_map_def SEC("maps") perf_map = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u64),
+ .max_entries= 1,
+};
+
+/* Writes the last PID that called sync to a map at index 0 */
+SEC("kprobe/sys_sync")
+int bpf_prog1(struct pt_regs *ctx)
+{
+ u64 pid = bpf_get_current_pid_tgid();
+ int idx = 0;
+
+ if (!bpf_current_task_under_cgroup(&cgroup_map, 0))
+ return 0;
+
+ bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/samples/bpf/test_current_task_under_cgroup_user.c
b/samples/bpf/test_current_task_under_cgroup_user.c
new file mode 100644
index 000..30b0bce
--- /dev/
