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authorSargun Dhillon <sargun@sargun.me>2016-12-02 02:42:18 -0800
committerDavid S. Miller <davem@davemloft.net>2016-12-03 16:07:11 -0500
commit1a922fee66c8a691bfec738b6a5694b2dbb2177d (patch)
treea2196acc64ef60499075d0711c4a0eecb0abef09 /samples
parent69a9d09b2251aeb968e76f39f2b89774312daa3d (diff)
downloadlinux-1a922fee66c8a691bfec738b6a5694b2dbb2177d.tar.bz2
samples, bpf: Refactor test_current_task_under_cgroup - separate out helpers
This patch modifies test_current_task_under_cgroup_user. The test has several helpers around creating a temporary environment for cgroup testing, and moving the current task around cgroups. This set of helpers can then be used in other tests. Signed-off-by: Sargun Dhillon <sargun@sargun.me> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/Makefile2
-rw-r--r--samples/bpf/cgroup_helpers.c177
-rw-r--r--samples/bpf/cgroup_helpers.h16
-rw-r--r--samples/bpf/test_current_task_under_cgroup_user.c108
4 files changed, 218 insertions, 85 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 13c3e1869890..57d84949e814 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -59,7 +59,7 @@ test_cgrp2_sock2-objs := bpf_load.o libbpf.o test_cgrp2_sock2.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-objs := bpf_load.o libbpf.o cgroup_helpers.o \
test_current_task_under_cgroup_user.o
trace_event-objs := bpf_load.o libbpf.o trace_event_user.o
sampleip-objs := bpf_load.o libbpf.o sampleip_user.o
diff --git a/samples/bpf/cgroup_helpers.c b/samples/bpf/cgroup_helpers.c
new file mode 100644
index 000000000000..9d1be9426401
--- /dev/null
+++ b/samples/bpf/cgroup_helpers.c
@@ -0,0 +1,177 @@
+#define _GNU_SOURCE
+#include <sched.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <linux/limits.h>
+#include <stdio.h>
+#include <linux/sched.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <ftw.h>
+
+
+#include "cgroup_helpers.h"
+
+/*
+ * To avoid relying on the system setup, when setup_cgroup_env is called
+ * we create a new mount namespace, and cgroup namespace. The cgroup2
+ * root is mounted at CGROUP_MOUNT_PATH
+ *
+ * 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.
+ *
+ * We assume /mnt exists.
+ */
+
+#define WALK_FD_LIMIT 16
+#define CGROUP_MOUNT_PATH "/mnt"
+#define CGROUP_WORK_DIR "/cgroup-test-work-dir"
+#define format_cgroup_path(buf, path) \
+ snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \
+ CGROUP_WORK_DIR, path)
+
+/**
+ * setup_cgroup_environment() - Setup the cgroup environment
+ *
+ * After calling this function, cleanup_cgroup_environment should be called
+ * once testing is complete.
+ *
+ * This function will print an error to stderr and return 1 if it is unable
+ * to setup the cgroup environment. If setup is successful, 0 is returned.
+ */
+int setup_cgroup_environment(void)
+{
+ char cgroup_workdir[PATH_MAX + 1];
+
+ format_cgroup_path(cgroup_workdir, "");
+
+ 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;
+ }
+
+ /* Cleanup existing failed runs, now that the environment is setup */
+ cleanup_cgroup_environment();
+
+ if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
+ log_err("mkdir cgroup work dir");
+ return 1;
+ }
+
+ return 0;
+}
+
+static int nftwfunc(const char *filename, const struct stat *statptr,
+ int fileflags, struct FTW *pfwt)
+{
+ if ((fileflags & FTW_D) && rmdir(filename))
+ log_err("Removing cgroup: %s", filename);
+ return 0;
+}
+
+
+static int join_cgroup_from_top(char *cgroup_path)
+{
+ char cgroup_procs_path[PATH_MAX + 1];
+ pid_t pid = getpid();
+ int fd, rc = 0;
+
+ snprintf(cgroup_procs_path, sizeof(cgroup_procs_path),
+ "%s/cgroup.procs", cgroup_path);
+
+ fd = open(cgroup_procs_path, O_WRONLY);
+ if (fd < 0) {
+ log_err("Opening Cgroup Procs: %s", cgroup_procs_path);
+ return 1;
+ }
+
+ if (dprintf(fd, "%d\n", pid) < 0) {
+ log_err("Joining Cgroup");
+ rc = 1;
+ }
+
+ close(fd);
+ return rc;
+}
+
+/**
+ * join_cgroup() - Join a cgroup
+ * @path: The cgroup path, relative to the workdir, to join
+ *
+ * This function expects a cgroup to already be created, relative to the cgroup
+ * work dir, and it joins it. For example, passing "/my-cgroup" as the path
+ * would actually put the calling process into the cgroup
+ * "/cgroup-test-work-dir/my-cgroup"
+ *
+ * On success, it returns 0, otherwise on failure it returns 1.
+ */
+int join_cgroup(char *path)
+{
+ char cgroup_path[PATH_MAX + 1];
+
+ format_cgroup_path(cgroup_path, path);
+ return join_cgroup_from_top(cgroup_path);
+}
+
+/**
+ * cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment
+ *
+ * This is an idempotent function to delete all temporary cgroups that
+ * have been created during the test, including the cgroup testing work
+ * directory.
+ *
+ * At call time, it moves the calling process to the root cgroup, and then
+ * runs the deletion process. It is idempotent, and should not fail, unless
+ * a process is lingering.
+ *
+ * On failure, it will print an error to stderr, and try to continue.
+ */
+void cleanup_cgroup_environment(void)
+{
+ char cgroup_workdir[PATH_MAX + 1];
+
+ format_cgroup_path(cgroup_workdir, "");
+ join_cgroup_from_top(CGROUP_MOUNT_PATH);
+ nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
+}
+
+/**
+ * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD
+ * @path: The cgroup path, relative to the workdir, to join
+ *
+ * This function creates a cgroup under the top level workdir and returns the
+ * file descriptor. It is idempotent.
+ *
+ * On success, it returns the file descriptor. On failure it returns 0.
+ * If there is a failure, it prints the error to stderr.
+ */
+int create_and_get_cgroup(char *path)
+{
+ char cgroup_path[PATH_MAX + 1];
+ int fd;
+
+ format_cgroup_path(cgroup_path, path);
+ if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
+ log_err("mkdiring cgroup");
+ return 0;
+ }
+
+ fd = open(cgroup_path, O_RDONLY);
+ if (fd < 0) {
+ log_err("Opening Cgroup");
+ return 0;
+ }
+
+ return fd;
+}
diff --git a/samples/bpf/cgroup_helpers.h b/samples/bpf/cgroup_helpers.h
new file mode 100644
index 000000000000..78c55207b6bd
--- /dev/null
+++ b/samples/bpf/cgroup_helpers.h
@@ -0,0 +1,16 @@
+#ifndef __CGROUP_HELPERS_H
+#define __CGROUP_HELPERS_H
+#include <errno.h>
+#include <string.h>
+
+#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__)
+
+
+int create_and_get_cgroup(char *path);
+int join_cgroup(char *path);
+int setup_cgroup_environment(void);
+void cleanup_cgroup_environment(void);
+
+#endif
diff --git a/samples/bpf/test_current_task_under_cgroup_user.c b/samples/bpf/test_current_task_under_cgroup_user.c
index 30b0bce884f9..95aaaa846130 100644
--- a/samples/bpf/test_current_task_under_cgroup_user.c
+++ b/samples/bpf/test_current_task_under_cgroup_user.c
@@ -11,50 +11,16 @@
#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>
+#include "cgroup_helpers.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;
-}
+#define CGROUP_PATH "/my-cgroup"
int main(int argc, char **argv)
{
- char filename[256];
- int cg2, idx = 0;
pid_t remote_pid, local_pid = getpid();
+ int cg2, idx = 0, rc = 0;
+ char filename[256];
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
if (load_bpf_file(filename)) {
@@ -62,47 +28,22 @@ int main(int argc, char **argv)
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 (setup_cgroup_environment())
+ goto err;
- if (mkdir(CGROUP_PATH, 0777) && errno != EEXIST) {
- log_err("mkdir cgroup");
- return 1;
- }
+ cg2 = create_and_get_cgroup(CGROUP_PATH);
- cg2 = open(CGROUP_PATH, O_RDONLY);
- if (cg2 < 0) {
- log_err("opening target cgroup");
- goto cleanup_cgroup_err;
- }
+ if (!cg2)
+ goto 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;
+ goto err;
}
+ if (join_cgroup(CGROUP_PATH))
+ goto err;
+
/*
* The installed helper program catched the sync call, and should
* write it to the map.
@@ -115,12 +56,12 @@ int main(int argc, char **argv)
fprintf(stderr,
"BPF Helper didn't write correct PID to map, but: %d\n",
remote_pid);
- goto leave_cgroup_err;
+ goto err;
}
/* Verify the negative scenario; leave the cgroup */
- if (join_cgroup(CGROUP_MOUNT_PATH))
- goto leave_cgroup_err;
+ if (join_cgroup("/"))
+ goto err;
remote_pid = 0;
bpf_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);
@@ -130,16 +71,15 @@ int main(int argc, char **argv)
if (local_pid == remote_pid) {
fprintf(stderr, "BPF cgroup negative test did not work\n");
- goto cleanup_cgroup_err;
+ goto err;
}
- rmdir(CGROUP_PATH);
- return 0;
+ goto out;
+err:
+ rc = 1;
- /* Error condition, cleanup */
-leave_cgroup_err:
- join_cgroup(CGROUP_MOUNT_PATH);
-cleanup_cgroup_err:
- rmdir(CGROUP_PATH);
- return 1;
+out:
+ close(cg2);
+ cleanup_cgroup_environment();
+ return rc;
}