Syscall name_to_handle_at() can be used to get cgroup id
for a particular cgroup path in user space. The selftest
got cgroup id from both user and kernel, and compare to
ensure they are equal to each other.
Signed-off-by: Yonghong Song <y...@fb.com>
---
tools/testing/selftests/bpf/.gitignore | 1 +
tools/testing/selftests/bpf/Makefile | 6 +-
tools/testing/selftests/bpf/cgroup_helpers.c | 57 +++++++++
tools/testing/selftests/bpf/cgroup_helpers.h | 1 +
tools/testing/selftests/bpf/get_cgroup_id_kern.c | 28 +++++
tools/testing/selftests/bpf/get_cgroup_id_user.c | 141 +++++++++++++++++++++++
6 files changed, 232 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/get_cgroup_id_kern.c
create mode 100644 tools/testing/selftests/bpf/get_cgroup_id_user.c
diff --git a/tools/testing/selftests/bpf/.gitignore
b/tools/testing/selftests/bpf/.gitignore
index 6ea8359..49938d7 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -18,3 +18,4 @@ urandom_read
test_btf
test_sockmap
test_lirc_mode2_user
+get_cgroup_id_user
diff --git a/tools/testing/selftests/bpf/Makefile
b/tools/testing/selftests/bpf/Makefile
index 553d181..607ed87 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -24,7 +24,7 @@ urandom_read: urandom_read.c
# Order correspond to 'make run_tests' order
TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map
test_progs \
test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
- test_sock test_btf test_sockmap test_lirc_mode2_user
+ test_sock test_btf test_sockmap test_lirc_mode2_user get_cgroup_id_user
TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o
test_obj_id.o \
test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o
sockmap_parse_prog.o \
@@ -34,7 +34,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o
test_tcp_estats.o test
sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o
test_adjust_tail.o \
test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o
\
test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
- test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o
test_lirc_mode2_kern.o
+ test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o
test_lirc_mode2_kern.o \
+ get_cgroup_id_kern.o
# Order correspond to 'make run_tests' order
TEST_PROGS := test_kmod.sh \
@@ -63,6 +64,7 @@ $(OUTPUT)/test_sock: cgroup_helpers.c
$(OUTPUT)/test_sock_addr: cgroup_helpers.c
$(OUTPUT)/test_sockmap: cgroup_helpers.c
$(OUTPUT)/test_progs: trace_helpers.c
+$(OUTPUT)/get_cgroup_id_user: cgroup_helpers.c
.PHONY: force
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c
b/tools/testing/selftests/bpf/cgroup_helpers.c
index f3bca3a..c87b4e0 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -6,6 +6,7 @@
#include <sys/types.h>
#include <linux/limits.h>
#include <stdio.h>
+#include <stdlib.h>
#include <linux/sched.h>
#include <fcntl.h>
#include <unistd.h>
@@ -176,3 +177,59 @@ int create_and_get_cgroup(char *path)
return fd;
}
+
+/**
+ * get_cgroup_id() - Get cgroup id for a particular cgroup path
+ * @path: The cgroup path, relative to the workdir, to join
+ *
+ * On success, it returns the cgroup id. On failure it returns 0,
+ * which is an invalid cgroup id.
+ * If there is a failure, it prints the error to stderr.
+ */
+unsigned long long get_cgroup_id(char *path)
+{
+ int dirfd, err, flags, mount_id, fhsize;
+ union {
+ unsigned long long cgid;
+ unsigned char raw_bytes[8];
+ } id;
+ char cgroup_workdir[PATH_MAX + 1];
+ struct file_handle *fhp, *fhp2;
+ unsigned long long ret = 0;
+
+ format_cgroup_path(cgroup_workdir, path);
+
+ dirfd = AT_FDCWD;
+ flags = 0;
+ fhsize = sizeof(*fhp);
+ fhp = calloc(1, fhsize);
+ if (!fhp) {
+ log_err("calloc");
+ return 0;
+ }
+ err = name_to_handle_at(dirfd, cgroup_workdir, fhp, &mount_id, flags);
+ if (err >= 0 || fhp->handle_bytes != 8) {
+ log_err("name_to_handle_at");
+ goto free_mem;
+ }
+
+ fhsize = sizeof(struct file_handle) + fhp->handle_bytes;
+ fhp2 = realloc(fhp, fhsize);
+ if (!fhp2) {
+ log_err("realloc");
+ goto free_mem;
+ }
+ err = name_to_handle_at(dirfd, cgroup_workdir, fhp2, &mount_id, flags);
+ fhp = fhp2;
+ if (err < 0) {
+ log_err("name_to_handle_at");
+ goto free_mem;
+ }
+
+ memcpy(id.raw_bytes, fhp->f_handle, 8);
+ ret = id.cgid;
+
+free_mem:
+ free(fhp);
+ return ret;
+}
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h
b/tools/testing/selftests/bpf/cgroup_helpers.h
index 06485e0..20a4a5d 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.h
+++ b/tools/testing/selftests/bpf/cgroup_helpers.h
@@ -13,5 +13,6 @@ int create_and_get_cgroup(char *path);
int join_cgroup(char *path);
int setup_cgroup_environment(void);
void cleanup_cgroup_environment(void);
+unsigned long long get_cgroup_id(char *path);
#endif
diff --git a/tools/testing/selftests/bpf/get_cgroup_id_kern.c
b/tools/testing/selftests/bpf/get_cgroup_id_kern.c
new file mode 100644
index 0000000..2cf8cb2
--- /dev/null
+++ b/tools/testing/selftests/bpf/get_cgroup_id_kern.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct bpf_map_def SEC("maps") cg_ids = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(__u32),
+ .value_size = sizeof(__u64),
+ .max_entries = 1,
+};
+
+SEC("tracepoint/syscalls/sys_enter_nanosleep")
+int trace(void *ctx)
+{
+ __u32 key = 0;
+ __u64 *val;
+
+ val = bpf_map_lookup_elem(&cg_ids, &key);
+ if (val)
+ *val = bpf_get_current_cgroup_id();
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by
libbpf.a */
diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c
b/tools/testing/selftests/bpf/get_cgroup_id_user.c
new file mode 100644
index 0000000..ea19a42
--- /dev/null
+++ b/tools/testing/selftests/bpf/get_cgroup_id_user.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <syscall.h>
+#include <unistd.h>
+#include <linux/perf_event.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <linux/bpf.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "cgroup_helpers.h"
+#include "bpf_rlimit.h"
+
+#define CHECK(condition, tag, format...) ({ \
+ int __ret = !!(condition); \
+ if (__ret) { \
+ printf("%s:FAIL:%s ", __func__, tag); \
+ printf(format); \
+ } else { \
+ printf("%s:PASS:%s\n", __func__, tag); \
+ } \
+ __ret; \
+})
+
+static int bpf_find_map(const char *test, struct bpf_object *obj,
+ const char *name)
+{
+ struct bpf_map *map;
+
+ map = bpf_object__find_map_by_name(obj, name);
+ if (!map)
+ return -1;
+ return bpf_map__fd(map);
+}
+
+#define TEST_CGROUP "/test-bpf-get-cgroup-id/"
+
+int main(int argc, char **argv)
+{
+ const char *probe_name = "syscalls/sys_enter_nanosleep";
+ const char *file = "get_cgroup_id_kern.o";
+ int err, bytes, efd, prog_fd, pmu_fd;
+ struct perf_event_attr attr = {};
+ int cgroup_fd, cgidmap_fd;
+ struct bpf_object *obj;
+ __u64 kcgid = 0, ucgid;
+ int exit_code = 1;
+ char buf[256];
+ __u32 key = 0;
+
+ err = setup_cgroup_environment();
+ if (CHECK(err, "setup_cgroup_environment", "err %d errno %d\n", err,
+ errno))
+ return 1;
+
+ cgroup_fd = create_and_get_cgroup(TEST_CGROUP);
+ if (CHECK(cgroup_fd < 0, "create_and_get_cgroup", "err %d errno %d\n",
+ cgroup_fd, errno))
+ goto cleanup_cgroup_env;
+
+ err = join_cgroup(TEST_CGROUP);
+ if (CHECK(err, "join_cgroup", "err %d errno %d\n", err, errno))
+ goto cleanup_cgroup_env;
+
+ err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
+ if (CHECK(err, "bpf_prog_load", "err %d errno %d\n", err, errno))
+ goto cleanup_cgroup_env;
+
+ cgidmap_fd = bpf_find_map(__func__, obj, "cg_ids");
+ if (CHECK(cgidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
+ cgidmap_fd, errno))
+ goto close_prog;
+
+ snprintf(buf, sizeof(buf),
+ "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+ efd = open(buf, O_RDONLY, 0);
+ if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
+ goto close_prog;
+ bytes = read(efd, buf, sizeof(buf));
+ close(efd);
+ if (CHECK(bytes <= 0 || bytes >= sizeof(buf), "read",
+ "bytes %d errno %d\n", bytes, errno))
+ goto close_prog;
+
+ attr.config = strtol(buf, NULL, 0);
+ attr.type = PERF_TYPE_TRACEPOINT;
+ attr.sample_type = PERF_SAMPLE_RAW;
+ attr.sample_period = 1;
+ attr.wakeup_events = 1;
+
+ /* attach to this pid so the all bpf invocations will be in the
+ * cgroup associated with this pid.
+ */
+ pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
+ if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", pmu_fd,
+ errno))
+ goto close_prog;
+
+ err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
+ if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n", err,
+ errno))
+ goto close_pmu;
+
+ err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
+ if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n", err,
+ errno))
+ goto close_pmu;
+
+ /* trigger some syscalls */
+ sleep(1);
+
+ err = bpf_map_lookup_elem(cgidmap_fd, &key, &kcgid);
+ if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))
+ goto close_pmu;
+
+ ucgid = get_cgroup_id(TEST_CGROUP);
+ if (CHECK(kcgid != ucgid, "compare_cgroup_id",
+ "kern cgid %llx user cgid %llx", kcgid, ucgid))
+ goto close_pmu;
+
+ exit_code = 0;
+ printf("%s:PASS\n", argv[0]);
+
+close_pmu:
+ close(pmu_fd);
+close_prog:
+ bpf_object__close(obj);
+cleanup_cgroup_env:
+ cleanup_cgroup_environment();
+ return exit_code;
+}
--
2.9.5
