1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * Copyright (C) 2020 Google LLC. 5 */ 6 7 #include <asm-generic/errno-base.h> 8 #include <sys/stat.h> 9 #include <test_progs.h> 10 #include <linux/limits.h> 11 12 #include "local_storage.skel.h" 13 #include "network_helpers.h" 14 15 #ifndef __NR_pidfd_open 16 #define __NR_pidfd_open 434 17 #endif 18 19 static inline int sys_pidfd_open(pid_t pid, unsigned int flags) 20 { 21 return syscall(__NR_pidfd_open, pid, flags); 22 } 23 24 static unsigned int duration; 25 26 #define TEST_STORAGE_VALUE 0xbeefdead 27 28 struct storage { 29 void *inode; 30 unsigned int value; 31 }; 32 33 /* Fork and exec the provided rm binary and return the exit code of the 34 * forked process and its pid. 35 */ 36 static int run_self_unlink(int *monitored_pid, const char *rm_path) 37 { 38 int child_pid, child_status, ret; 39 int null_fd; 40 41 child_pid = fork(); 42 if (child_pid == 0) { 43 null_fd = open("/dev/null", O_WRONLY); 44 dup2(null_fd, STDOUT_FILENO); 45 dup2(null_fd, STDERR_FILENO); 46 close(null_fd); 47 48 *monitored_pid = getpid(); 49 /* Use the copied /usr/bin/rm to delete itself 50 * /tmp/copy_of_rm /tmp/copy_of_rm. 51 */ 52 ret = execlp(rm_path, rm_path, rm_path, NULL); 53 if (ret) 54 exit(errno); 55 } else if (child_pid > 0) { 56 waitpid(child_pid, &child_status, 0); 57 return WEXITSTATUS(child_status); 58 } 59 60 return -EINVAL; 61 } 62 63 static bool check_syscall_operations(int map_fd, int obj_fd) 64 { 65 struct storage val = { .value = TEST_STORAGE_VALUE }, 66 lookup_val = { .value = 0 }; 67 int err; 68 69 /* Looking up an existing element should fail initially */ 70 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); 71 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem", 72 "err:%d errno:%d\n", err, errno)) 73 return false; 74 75 /* Create a new element */ 76 err = bpf_map_update_elem(map_fd, &obj_fd, &val, BPF_NOEXIST); 77 if (CHECK(err < 0, "bpf_map_update_elem", "err:%d errno:%d\n", err, 78 errno)) 79 return false; 80 81 /* Lookup the newly created element */ 82 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); 83 if (CHECK(err < 0, "bpf_map_lookup_elem", "err:%d errno:%d", err, 84 errno)) 85 return false; 86 87 /* Check the value of the newly created element */ 88 if (CHECK(lookup_val.value != val.value, "bpf_map_lookup_elem", 89 "value got = %x errno:%d", lookup_val.value, val.value)) 90 return false; 91 92 err = bpf_map_delete_elem(map_fd, &obj_fd); 93 if (CHECK(err, "bpf_map_delete_elem()", "err:%d errno:%d\n", err, 94 errno)) 95 return false; 96 97 /* The lookup should fail, now that the element has been deleted */ 98 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0); 99 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem", 100 "err:%d errno:%d\n", err, errno)) 101 return false; 102 103 return true; 104 } 105 106 void test_test_local_storage(void) 107 { 108 char tmp_dir_path[] = "/tmp/local_storageXXXXXX"; 109 int err, serv_sk = -1, task_fd = -1, rm_fd = -1; 110 struct local_storage *skel = NULL; 111 char tmp_exec_path[64]; 112 char cmd[256]; 113 114 skel = local_storage__open_and_load(); 115 if (CHECK(!skel, "skel_load", "lsm skeleton failed\n")) 116 goto close_prog; 117 118 err = local_storage__attach(skel); 119 if (CHECK(err, "attach", "lsm attach failed: %d\n", err)) 120 goto close_prog; 121 122 task_fd = sys_pidfd_open(getpid(), 0); 123 if (CHECK(task_fd < 0, "pidfd_open", 124 "failed to get pidfd err:%d, errno:%d", task_fd, errno)) 125 goto close_prog; 126 127 if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map), 128 task_fd)) 129 goto close_prog; 130 131 if (CHECK(!mkdtemp(tmp_dir_path), "mkdtemp", 132 "unable to create tmpdir: %d\n", errno)) 133 goto close_prog; 134 135 snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm", 136 tmp_dir_path); 137 snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path); 138 if (CHECK_FAIL(system(cmd))) 139 goto close_prog_rmdir; 140 141 rm_fd = open(tmp_exec_path, O_RDONLY); 142 if (CHECK(rm_fd < 0, "open", "failed to open %s err:%d, errno:%d", 143 tmp_exec_path, rm_fd, errno)) 144 goto close_prog_rmdir; 145 146 if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map), 147 rm_fd)) 148 goto close_prog_rmdir; 149 150 /* Sets skel->bss->monitored_pid to the pid of the forked child 151 * forks a child process that executes tmp_exec_path and tries to 152 * unlink its executable. This operation should be denied by the loaded 153 * LSM program. 154 */ 155 err = run_self_unlink(&skel->bss->monitored_pid, tmp_exec_path); 156 if (CHECK(err != EPERM, "run_self_unlink", "err %d want EPERM\n", err)) 157 goto close_prog_rmdir; 158 159 /* Set the process being monitored to be the current process */ 160 skel->bss->monitored_pid = getpid(); 161 162 /* Move copy_of_rm to a new location so that it triggers the 163 * inode_rename LSM hook with a new_dentry that has a NULL inode ptr. 164 */ 165 snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr", 166 tmp_dir_path, tmp_dir_path); 167 if (CHECK_FAIL(system(cmd))) 168 goto close_prog_rmdir; 169 170 CHECK(skel->data->inode_storage_result != 0, "inode_storage_result", 171 "inode_local_storage not set\n"); 172 173 serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0); 174 if (CHECK(serv_sk < 0, "start_server", "failed to start server\n")) 175 goto close_prog_rmdir; 176 177 CHECK(skel->data->sk_storage_result != 0, "sk_storage_result", 178 "sk_local_storage not set\n"); 179 180 if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map), 181 serv_sk)) 182 goto close_prog_rmdir; 183 184 close_prog_rmdir: 185 snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path); 186 system(cmd); 187 close_prog: 188 close(serv_sk); 189 close(rm_fd); 190 close(task_fd); 191 local_storage__destroy(skel); 192 } 193