diff options
Diffstat (limited to 'tools/testing/selftests/bpf/prog_tests/test_local_storage.c')
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/test_local_storage.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/test_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c new file mode 100644 index 000000000..9c77cd6b1 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2020 Google LLC. + */ + +#include <asm-generic/errno-base.h> +#include <sys/stat.h> +#include <test_progs.h> +#include <linux/limits.h> + +#include "local_storage.skel.h" +#include "network_helpers.h" +#include "task_local_storage_helpers.h" + +static unsigned int duration; + +#define TEST_STORAGE_VALUE 0xbeefdead + +struct storage { + void *inode; + unsigned int value; +}; + +/* Fork and exec the provided rm binary and return the exit code of the + * forked process and its pid. + */ +static int run_self_unlink(int *monitored_pid, const char *rm_path) +{ + int child_pid, child_status, ret; + int null_fd; + + child_pid = fork(); + if (child_pid == 0) { + null_fd = open("/dev/null", O_WRONLY); + dup2(null_fd, STDOUT_FILENO); + dup2(null_fd, STDERR_FILENO); + close(null_fd); + + *monitored_pid = getpid(); + /* Use the copied /usr/bin/rm to delete itself + * /tmp/copy_of_rm /tmp/copy_of_rm. + */ + ret = execlp(rm_path, rm_path, rm_path, NULL); + if (ret) + exit(errno); + } else if (child_pid > 0) { + waitpid(child_pid, &child_status, 0); + return WEXITSTATUS(child_status); + } + + return -EINVAL; +} + +static bool check_syscall_operations(int map_fd, int obj_fd) +{ + struct storage val = { .value = TEST_STORAGE_VALUE }, + lookup_val = { .value = 0 }; + int err; + + /* Looking up an existing element should fail initially */ + err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); + if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem", + "err:%d errno:%d\n", err, errno)) + return false; + + /* Create a new element */ + err = bpf_map_update_elem(map_fd, &obj_fd, &val, BPF_NOEXIST); + if (CHECK(err < 0, "bpf_map_update_elem", "err:%d errno:%d\n", err, + errno)) + return false; + + /* Lookup the newly created element */ + err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); + if (CHECK(err < 0, "bpf_map_lookup_elem", "err:%d errno:%d", err, + errno)) + return false; + + /* Check the value of the newly created element */ + if (CHECK(lookup_val.value != val.value, "bpf_map_lookup_elem", + "value got = %x errno:%d", lookup_val.value, val.value)) + return false; + + err = bpf_map_delete_elem(map_fd, &obj_fd); + if (CHECK(err, "bpf_map_delete_elem()", "err:%d errno:%d\n", err, + errno)) + return false; + + /* The lookup should fail, now that the element has been deleted */ + err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); + if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem", + "err:%d errno:%d\n", err, errno)) + return false; + + return true; +} + +void test_test_local_storage(void) +{ + char tmp_dir_path[] = "/tmp/local_storageXXXXXX"; + int err, serv_sk = -1, task_fd = -1, rm_fd = -1; + struct local_storage *skel = NULL; + char tmp_exec_path[64]; + char cmd[256]; + + skel = local_storage__open_and_load(); + if (CHECK(!skel, "skel_load", "lsm skeleton failed\n")) + goto close_prog; + + err = local_storage__attach(skel); + if (CHECK(err, "attach", "lsm attach failed: %d\n", err)) + goto close_prog; + + task_fd = sys_pidfd_open(getpid(), 0); + if (CHECK(task_fd < 0, "pidfd_open", + "failed to get pidfd err:%d, errno:%d", task_fd, errno)) + goto close_prog; + + if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map), + task_fd)) + goto close_prog; + + if (CHECK(!mkdtemp(tmp_dir_path), "mkdtemp", + "unable to create tmpdir: %d\n", errno)) + goto close_prog; + + snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm", + tmp_dir_path); + snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path); + if (CHECK_FAIL(system(cmd))) + goto close_prog_rmdir; + + rm_fd = open(tmp_exec_path, O_RDONLY); + if (CHECK(rm_fd < 0, "open", "failed to open %s err:%d, errno:%d", + tmp_exec_path, rm_fd, errno)) + goto close_prog_rmdir; + + if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map), + rm_fd)) + goto close_prog_rmdir; + + /* Sets skel->bss->monitored_pid to the pid of the forked child + * forks a child process that executes tmp_exec_path and tries to + * unlink its executable. This operation should be denied by the loaded + * LSM program. + */ + err = run_self_unlink(&skel->bss->monitored_pid, tmp_exec_path); + if (CHECK(err != EPERM, "run_self_unlink", "err %d want EPERM\n", err)) + goto close_prog_rmdir; + + /* Set the process being monitored to be the current process */ + skel->bss->monitored_pid = getpid(); + + /* Move copy_of_rm to a new location so that it triggers the + * inode_rename LSM hook with a new_dentry that has a NULL inode ptr. + */ + snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr", + tmp_dir_path, tmp_dir_path); + if (CHECK_FAIL(system(cmd))) + goto close_prog_rmdir; + + CHECK(skel->data->inode_storage_result != 0, "inode_storage_result", + "inode_local_storage not set\n"); + + serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0); + if (CHECK(serv_sk < 0, "start_server", "failed to start server\n")) + goto close_prog_rmdir; + + CHECK(skel->data->sk_storage_result != 0, "sk_storage_result", + "sk_local_storage not set\n"); + + if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map), + serv_sk)) + goto close_prog_rmdir; + +close_prog_rmdir: + snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path); + system(cmd); +close_prog: + close(serv_sk); + close(rm_fd); + close(task_fd); + local_storage__destroy(skel); +} |