tools/testing/selftests/bpf/prog_tests/test_local_storage.c

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