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-rw-r--r--samples/bpf/Makefile5
-rw-r--r--samples/bpf/bpf_helpers.h2
-rw-r--r--samples/bpf/test_current_task_under_cgroup_kern.c43
-rw-r--r--samples/bpf/test_current_task_under_cgroup_user.c145
4 files changed, 195 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 90ebf7d35c07..eb582c6264c3 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 cbc52df165b4..5e4c41e256b8 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 000000000000..86b28d7d6c99
--- /dev/null
+++ b/samples/bpf/test_current_task_under_cgroup_kern.c
@@ -0,0 +1,43 @@
+/* Copyright (c) 2016 Sargun Dhillon <sargun@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"
+#include <uapi/linux/utsname.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,
+};
+
+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 000000000000..30b0bce884f9
--- /dev/null
+++ b/samples/bpf/test_current_task_under_cgroup_user.c
@@ -0,0 +1,145 @@
+/* Copyright (c) 2016 Sargun Dhillon <sargun@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.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <linux/bpf.h>
+#include <unistd.h>
+#include "libbpf.h"
+#include "bpf_load.h"
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <linux/bpf.h>
+#include <sched.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <linux/limits.h>
+
+#define CGROUP_MOUNT_PATH "/mnt"
+#define CGROUP_PATH "/mnt/my-cgroup"
+
+#define clean_errno() (errno == 0 ? "None" : strerror(errno))
+#define log_err(MSG, ...) fprintf(stderr, "(%s:%d: errno: %s) " MSG "\n", \
+ __FILE__, __LINE__, clean_errno(), ##__VA_ARGS__)
+
+static int join_cgroup(char *path)
+{
+ int fd, rc = 0;
+ pid_t pid = getpid();
+ char cgroup_path[PATH_MAX + 1];
+
+ snprintf(cgroup_path, sizeof(cgroup_path), "%s/cgroup.procs", path);
+
+ fd = open(cgroup_path, O_WRONLY);
+ if (fd < 0) {
+ log_err("Opening Cgroup");
+ return 1;
+ }
+
+ if (dprintf(fd, "%d\n", pid) < 0) {
+ log_err("Joining Cgroup");
+ rc = 1;
+ }
+ close(fd);
+ return rc;
+}
+
+int main(int argc, char **argv)
+{
+ char filename[256];
+ int cg2, idx = 0;
+ pid_t remote_pid, local_pid = getpid();
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ /*
+ * This is to avoid interfering with existing cgroups. Unfortunately,
+ * most people don't have cgroupv2 enabled at this point in time.
+ * It's easier to create our own mount namespace and manage it
+ * ourselves.
+ */
+ if (unshare(CLONE_NEWNS)) {
+ log_err("unshare");
+ return 1;
+ }
+
+ if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
+ log_err("mount fakeroot");
+ return 1;
+ }
+
+ if (mount("none", CGROUP_MOUNT_PATH, "cgroup2", 0, NULL)) {
+ log_err("mount cgroup2");
+ return 1;
+ }
+
+ if (mkdir(CGROUP_PATH, 0777) && errno != EEXIST) {
+ log_err("mkdir cgroup");
+ return 1;
+ }
+
+ cg2 = open(CGROUP_PATH, O_RDONLY);
+ if (cg2 < 0) {
+ log_err("opening target cgroup");
+ goto cleanup_cgroup_err;
+ }
+
+ if (bpf_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {
+ log_err("Adding target cgroup to map");
+ goto cleanup_cgroup_err;
+ }
+ if (join_cgroup("/mnt/my-cgroup")) {
+ log_err("Leaving target cgroup");
+ goto cleanup_cgroup_err;
+ }
+
+ /*
+ * The installed helper program catched the sync call, and should
+ * write it to the map.
+ */
+
+ sync();
+ bpf_lookup_elem(map_fd[1], &idx, &remote_pid);
+
+ if (local_pid != remote_pid) {
+ fprintf(stderr,
+ "BPF Helper didn't write correct PID to map, but: %d\n",
+ remote_pid);
+ goto leave_cgroup_err;
+ }
+
+ /* Verify the negative scenario; leave the cgroup */
+ if (join_cgroup(CGROUP_MOUNT_PATH))
+ goto leave_cgroup_err;
+
+ remote_pid = 0;
+ bpf_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
+
+ sync();
+ bpf_lookup_elem(map_fd[1], &idx, &remote_pid);
+
+ if (local_pid == remote_pid) {
+ fprintf(stderr, "BPF cgroup negative test did not work\n");
+ goto cleanup_cgroup_err;
+ }
+
+ rmdir(CGROUP_PATH);
+ return 0;
+
+ /* Error condition, cleanup */
+leave_cgroup_err:
+ join_cgroup(CGROUP_MOUNT_PATH);
+cleanup_cgroup_err:
+ rmdir(CGROUP_PATH);
+ return 1;
+}