selftests/cgroup: add tests for cloning into cgroups
authorChristian Brauner <christian.brauner@ubuntu.com>
Wed, 5 Feb 2020 13:26:23 +0000 (14:26 +0100)
committerTejun Heo <tj@kernel.org>
Wed, 12 Feb 2020 22:57:51 +0000 (17:57 -0500)
Expand the cgroup test-suite to include tests for CLONE_INTO_CGROUP.
This adds the following tests:
- CLONE_INTO_CGROUP manages to clone a process directly into a correctly
  delegated cgroup
- CLONE_INTO_CGROUP fails to clone a process into a cgroup that has been
  removed after we've opened an fd to it
- CLONE_INTO_CGROUP fails to clone a process into an invalid domain
  cgroup
- CLONE_INTO_CGROUP adheres to the no internal process constraint
- CLONE_INTO_CGROUP works with the freezer feature

Cc: Tejun Heo <tj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: cgroups@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
tools/testing/selftests/cgroup/Makefile
tools/testing/selftests/cgroup/cgroup_util.c
tools/testing/selftests/cgroup/cgroup_util.h
tools/testing/selftests/cgroup/test_core.c
tools/testing/selftests/clone3/clone3_selftests.h

index 66aafe1..967f268 100644 (file)
@@ -11,6 +11,6 @@ TEST_GEN_PROGS += test_freezer
 
 include ../lib.mk
 
-$(OUTPUT)/test_memcontrol: cgroup_util.c
-$(OUTPUT)/test_core: cgroup_util.c
-$(OUTPUT)/test_freezer: cgroup_util.c
+$(OUTPUT)/test_memcontrol: cgroup_util.c ../clone3/clone3_selftests.h
+$(OUTPUT)/test_core: cgroup_util.c ../clone3/clone3_selftests.h
+$(OUTPUT)/test_freezer: cgroup_util.c ../clone3/clone3_selftests.h
index 8f7131d..8a637ca 100644 (file)
@@ -15,6 +15,7 @@
 #include <unistd.h>
 
 #include "cgroup_util.h"
+#include "../clone3/clone3_selftests.h"
 
 static ssize_t read_text(const char *path, char *buf, size_t max_len)
 {
@@ -331,12 +332,112 @@ int cg_run(const char *cgroup,
        }
 }
 
+pid_t clone_into_cgroup(int cgroup_fd)
+{
+#ifdef CLONE_ARGS_SIZE_VER2
+       pid_t pid;
+
+       struct clone_args args = {
+               .flags = CLONE_INTO_CGROUP,
+               .exit_signal = SIGCHLD,
+               .cgroup = cgroup_fd,
+       };
+
+       pid = sys_clone3(&args, sizeof(struct clone_args));
+       /*
+        * Verify that this is a genuine test failure:
+        * ENOSYS -> clone3() not available
+        * E2BIG  -> CLONE_INTO_CGROUP not available
+        */
+       if (pid < 0 && (errno == ENOSYS || errno == E2BIG))
+               goto pretend_enosys;
+
+       return pid;
+
+pretend_enosys:
+#endif
+       errno = ENOSYS;
+       return -ENOSYS;
+}
+
+int clone_reap(pid_t pid, int options)
+{
+       int ret;
+       siginfo_t info = {
+               .si_signo = 0,
+       };
+
+again:
+       ret = waitid(P_PID, pid, &info, options | __WALL | __WNOTHREAD);
+       if (ret < 0) {
+               if (errno == EINTR)
+                       goto again;
+               return -1;
+       }
+
+       if (options & WEXITED) {
+               if (WIFEXITED(info.si_status))
+                       return WEXITSTATUS(info.si_status);
+       }
+
+       if (options & WSTOPPED) {
+               if (WIFSTOPPED(info.si_status))
+                       return WSTOPSIG(info.si_status);
+       }
+
+       if (options & WCONTINUED) {
+               if (WIFCONTINUED(info.si_status))
+                       return 0;
+       }
+
+       return -1;
+}
+
+int dirfd_open_opath(const char *dir)
+{
+       return open(dir, O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW | O_PATH);
+}
+
+#define close_prot_errno(fd)                                                   \
+       if (fd >= 0) {                                                         \
+               int _e_ = errno;                                               \
+               close(fd);                                                     \
+               errno = _e_;                                                   \
+       }
+
+static int clone_into_cgroup_run_nowait(const char *cgroup,
+                                       int (*fn)(const char *cgroup, void *arg),
+                                       void *arg)
+{
+       int cgroup_fd;
+       pid_t pid;
+
+       cgroup_fd =  dirfd_open_opath(cgroup);
+       if (cgroup_fd < 0)
+               return -1;
+
+       pid = clone_into_cgroup(cgroup_fd);
+       close_prot_errno(cgroup_fd);
+       if (pid == 0)
+               exit(fn(cgroup, arg));
+
+       return pid;
+}
+
 int cg_run_nowait(const char *cgroup,
                  int (*fn)(const char *cgroup, void *arg),
                  void *arg)
 {
        int pid;
 
+       pid = clone_into_cgroup_run_nowait(cgroup, fn, arg);
+       if (pid > 0)
+               return pid;
+
+       /* Genuine test failure. */
+       if (pid < 0 && errno != ENOSYS)
+               return -1;
+
        pid = fork();
        if (pid == 0) {
                char buf[64];
@@ -450,3 +551,28 @@ int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
 
        return strstr(buf, needle) ? 0 : -1;
 }
+
+int clone_into_cgroup_run_wait(const char *cgroup)
+{
+       int cgroup_fd;
+       pid_t pid;
+
+       cgroup_fd =  dirfd_open_opath(cgroup);
+       if (cgroup_fd < 0)
+               return -1;
+
+       pid = clone_into_cgroup(cgroup_fd);
+       close_prot_errno(cgroup_fd);
+       if (pid < 0)
+               return -1;
+
+       if (pid == 0)
+               exit(EXIT_SUCCESS);
+
+       /*
+        * We don't care whether this fails. We only care whether the initial
+        * clone succeeded.
+        */
+       (void)clone_reap(pid, WEXITED);
+       return 0;
+}
index 49c54fb..5a1305d 100644 (file)
@@ -50,3 +50,7 @@ extern int cg_wait_for_proc_count(const char *cgroup, int count);
 extern int cg_killall(const char *cgroup);
 extern ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size);
 extern int proc_read_strstr(int pid, bool thread, const char *item, const char *needle);
+extern pid_t clone_into_cgroup(int cgroup_fd);
+extern int clone_reap(pid_t pid, int options);
+extern int clone_into_cgroup_run_wait(const char *cgroup);
+extern int dirfd_open_opath(const char *dir);
index 8289d3f..3df648c 100644 (file)
@@ -137,8 +137,11 @@ cleanup:
 static int test_cgcore_populated(const char *root)
 {
        int ret = KSFT_FAIL;
+       int err;
        char *cg_test_a = NULL, *cg_test_b = NULL;
        char *cg_test_c = NULL, *cg_test_d = NULL;
+       int cgroup_fd = -EBADF;
+       pid_t pid;
 
        cg_test_a = cg_name(root, "cg_test_a");
        cg_test_b = cg_name(root, "cg_test_a/cg_test_b");
@@ -190,6 +193,52 @@ static int test_cgcore_populated(const char *root)
        if (cg_read_strcmp(cg_test_d, "cgroup.events", "populated 0\n"))
                goto cleanup;
 
+       /* Test that we can directly clone into a new cgroup. */
+       cgroup_fd = dirfd_open_opath(cg_test_d);
+       if (cgroup_fd < 0)
+               goto cleanup;
+
+       pid = clone_into_cgroup(cgroup_fd);
+       if (pid < 0) {
+               if (errno == ENOSYS)
+                       goto cleanup_pass;
+               goto cleanup;
+       }
+
+       if (pid == 0) {
+               if (raise(SIGSTOP))
+                       exit(EXIT_FAILURE);
+               exit(EXIT_SUCCESS);
+       }
+
+       err = cg_read_strcmp(cg_test_d, "cgroup.events", "populated 1\n");
+
+       (void)clone_reap(pid, WSTOPPED);
+       (void)kill(pid, SIGCONT);
+       (void)clone_reap(pid, WEXITED);
+
+       if (err)
+               goto cleanup;
+
+       if (cg_read_strcmp(cg_test_d, "cgroup.events", "populated 0\n"))
+               goto cleanup;
+
+       /* Remove cgroup. */
+       if (cg_test_d) {
+               cg_destroy(cg_test_d);
+               free(cg_test_d);
+               cg_test_d = NULL;
+       }
+
+       pid = clone_into_cgroup(cgroup_fd);
+       if (pid < 0)
+               goto cleanup_pass;
+       if (pid == 0)
+               exit(EXIT_SUCCESS);
+       (void)clone_reap(pid, WEXITED);
+       goto cleanup;
+
+cleanup_pass:
        ret = KSFT_PASS;
 
 cleanup:
@@ -205,6 +254,8 @@ cleanup:
        free(cg_test_c);
        free(cg_test_b);
        free(cg_test_a);
+       if (cgroup_fd >= 0)
+               close(cgroup_fd);
        return ret;
 }
 
@@ -248,6 +299,16 @@ static int test_cgcore_invalid_domain(const char *root)
        if (errno != EOPNOTSUPP)
                goto cleanup;
 
+       if (!clone_into_cgroup_run_wait(child))
+               goto cleanup;
+
+       if (errno == ENOSYS)
+               goto cleanup_pass;
+
+       if (errno != EOPNOTSUPP)
+               goto cleanup;
+
+cleanup_pass:
        ret = KSFT_PASS;
 
 cleanup:
@@ -457,6 +518,9 @@ static int test_cgcore_internal_process_constraint(const char *root)
        if (!cg_enter_current(parent))
                goto cleanup;
 
+       if (!clone_into_cgroup_run_wait(parent))
+               goto cleanup;
+
        ret = KSFT_PASS;
 
 cleanup:
index a3f2c8a..91c1a78 100644 (file)
@@ -5,12 +5,24 @@
 
 #define _GNU_SOURCE
 #include <sched.h>
+#include <linux/sched.h>
+#include <linux/types.h>
 #include <stdint.h>
 #include <syscall.h>
-#include <linux/types.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
 
 #define ptr_to_u64(ptr) ((__u64)((uintptr_t)(ptr)))
 
+#ifndef CLONE_INTO_CGROUP
+#define CLONE_INTO_CGROUP 0x200000000ULL /* Clone into a specific cgroup given the right permissions. */
+#endif
+
+#ifndef CLONE_ARGS_SIZE_VER0
+#define CLONE_ARGS_SIZE_VER0 64
+#endif
+
 #ifndef __NR_clone3
 #define __NR_clone3 -1
 struct clone_args {
@@ -22,10 +34,13 @@ struct clone_args {
        __aligned_u64 stack;
        __aligned_u64 stack_size;
        __aligned_u64 tls;
+#define CLONE_ARGS_SIZE_VER1 80
        __aligned_u64 set_tid;
        __aligned_u64 set_tid_size;
+#define CLONE_ARGS_SIZE_VER2 88
+       __aligned_u64 cgroup;
 };
-#endif
+#endif /* __NR_clone3 */
 
 static pid_t sys_clone3(struct clone_args *args, size_t size)
 {