tools/testing/selftests/firmware/fw_namespace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Test triggering of loading of firmware from different mount
   3  * namespaces. Expect firmware to be always loaded from the mount
   4  * namespace of PID 1. */
   5 #define _GNU_SOURCE
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <sched.h>
   9 #include <stdarg.h>
  10 #include <stdbool.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <sys/mount.h>
  15 #include <sys/stat.h>
  16 #include <sys/types.h>
  17 #include <sys/wait.h>
  18 #include <unistd.h>
  19
  20 static char *fw_path = NULL;
  21
  22 static void die(char *fmt, ...)
  23 {
  24         va_list ap;
  25
  26         va_start(ap, fmt);
  27         vfprintf(stderr, fmt, ap);
  28         va_end(ap);
  29         if (fw_path)
  30                 unlink(fw_path);
  31         umount("/lib/firmware");
  32         exit(EXIT_FAILURE);
  33 }
  34
  35 static void trigger_fw(const char *fw_name, const char *sys_path)
  36 {
  37         int fd;
  38
  39         fd = open(sys_path, O_WRONLY);
  40         if (fd < 0)
  41                 die("open failed: %s\n",
  42                     strerror(errno));
  43         if (write(fd, fw_name, strlen(fw_name)) != strlen(fw_name))
  44                 exit(EXIT_FAILURE);
  45         close(fd);
  46 }
  47
  48 static void setup_fw(const char *fw_path)
  49 {
  50         int fd;
  51         const char fw[] = "ABCD0123";
  52
  53         fd = open(fw_path, O_WRONLY | O_CREAT, 0600);
  54         if (fd < 0)
  55                 die("open failed: %s\n",
  56                     strerror(errno));
  57         if (write(fd, fw, sizeof(fw) -1) != sizeof(fw) -1)
  58                 die("write failed: %s\n",
  59                     strerror(errno));
  60         close(fd);
  61 }
  62
  63 static bool test_fw_in_ns(const char *fw_name, const char *sys_path, bool block_fw_in_parent_ns)
  64 {
  65         pid_t child;
  66
  67         if (block_fw_in_parent_ns)
  68                 if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
  69                         die("blocking firmware in parent ns failed\n");
  70
  71         child = fork();
  72         if (child == -1) {
  73                 die("fork failed: %s\n",
  74                         strerror(errno));
  75         }
  76         if (child != 0) { /* parent */
  77                 pid_t pid;
  78                 int status;
  79
  80                 pid = waitpid(child, &status, 0);
  81                 if (pid == -1) {
  82                         die("waitpid failed: %s\n",
  83                                 strerror(errno));
  84                 }
  85                 if (pid != child) {
  86                         die("waited for %d got %d\n",
  87                                 child, pid);
  88                 }
  89                 if (!WIFEXITED(status)) {
  90                         die("child did not terminate cleanly\n");
  91                 }
  92                 if (block_fw_in_parent_ns)
  93                         umount("/lib/firmware");
  94                 return WEXITSTATUS(status) == EXIT_SUCCESS;
  95         }
  96
  97         if (unshare(CLONE_NEWNS) != 0) {
  98                 die("unshare(CLONE_NEWNS) failed: %s\n",
  99                         strerror(errno));
 100         }
 101         if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) == -1)
 102                 die("remount root in child ns failed\n");
 103
 104         if (!block_fw_in_parent_ns) {
 105                 if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
 106                         die("blocking firmware in child ns failed\n");
 107         } else
 108                 umount("/lib/firmware");
 109
 110         trigger_fw(fw_name, sys_path);
 111
 112         exit(EXIT_SUCCESS);
 113 }
 114
 115 int main(int argc, char **argv)
 116 {
 117         const char *fw_name = "test-firmware.bin";
 118         char *sys_path;
 119         if (argc != 2)
 120                 die("usage: %s sys_path\n", argv[0]);
 121
 122         /* Mount tmpfs to /lib/firmware so we don't have to assume
 123            that it is writable for us.*/
 124         if (mount("test", "/lib/firmware", "tmpfs", 0, NULL) == -1)
 125                 die("mounting tmpfs to /lib/firmware failed\n");
 126
 127         sys_path = argv[1];
 128         if (asprintf(&fw_path, "/lib/firmware/%s", fw_name) < 0)
 129                 die("error: failed to build full fw_path\n");
 130
 131         setup_fw(fw_path);
 132
 133         setvbuf(stdout, NULL, _IONBF, 0);
 134         /* Positive case: firmware in PID1 mount namespace */
 135         printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
 136         if (!test_fw_in_ns(fw_name, sys_path, false))
 137                 die("error: failed to access firmware\n");
 138
 139         /* Negative case: firmware in child mount namespace, expected to fail */
 140         printf("Testing with firmware in child namespace\n");
 141         if (test_fw_in_ns(fw_name, sys_path, true))
 142                 die("error: firmware access did not fail\n");
 143
 144         unlink(fw_path);
 145         free(fw_path);
 146         umount("/lib/firmware");
 147         exit(EXIT_SUCCESS);
 148 }