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 #ifndef CLONE_NEWNS
  21 # define CLONE_NEWNS 0x00020000
  22 #endif
  23
  24 static char *fw_path = NULL;
  25
  26 static void die(char *fmt, ...)
  27 {
  28         va_list ap;
  29
  30         va_start(ap, fmt);
  31         vfprintf(stderr, fmt, ap);
  32         va_end(ap);
  33         if (fw_path)
  34                 unlink(fw_path);
  35         umount("/lib/firmware");
  36         exit(EXIT_FAILURE);
  37 }
  38
  39 static void trigger_fw(const char *fw_name, const char *sys_path)
  40 {
  41         int fd;
  42
  43         fd = open(sys_path, O_WRONLY);
  44         if (fd < 0)
  45                 die("open failed: %s\n",
  46                     strerror(errno));
  47         if (write(fd, fw_name, strlen(fw_name)) != strlen(fw_name))
  48                 exit(EXIT_FAILURE);
  49         close(fd);
  50 }
  51
  52 static void setup_fw(const char *fw_path)
  53 {
  54         int fd;
  55         const char fw[] = "ABCD0123";
  56
  57         fd = open(fw_path, O_WRONLY | O_CREAT, 0600);
  58         if (fd < 0)
  59                 die("open failed: %s\n",
  60                     strerror(errno));
  61         if (write(fd, fw, sizeof(fw) -1) != sizeof(fw) -1)
  62                 die("write failed: %s\n",
  63                     strerror(errno));
  64         close(fd);
  65 }
  66
  67 static bool test_fw_in_ns(const char *fw_name, const char *sys_path, bool block_fw_in_parent_ns)
  68 {
  69         pid_t child;
  70
  71         if (block_fw_in_parent_ns)
  72                 if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
  73                         die("blocking firmware in parent ns failed\n");
  74
  75         child = fork();
  76         if (child == -1) {
  77                 die("fork failed: %s\n",
  78                         strerror(errno));
  79         }
  80         if (child != 0) { /* parent */
  81                 pid_t pid;
  82                 int status;
  83
  84                 pid = waitpid(child, &status, 0);
  85                 if (pid == -1) {
  86                         die("waitpid failed: %s\n",
  87                                 strerror(errno));
  88                 }
  89                 if (pid != child) {
  90                         die("waited for %d got %d\n",
  91                                 child, pid);
  92                 }
  93                 if (!WIFEXITED(status)) {
  94                         die("child did not terminate cleanly\n");
  95                 }
  96                 if (block_fw_in_parent_ns)
  97                         umount("/lib/firmware");
  98                 return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;
  99         }
 100
 101         if (unshare(CLONE_NEWNS) != 0) {
 102                 die("unshare(CLONE_NEWNS) failed: %s\n",
 103                         strerror(errno));
 104         }
 105         if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) == -1)
 106                 die("remount root in child ns failed\n");
 107
 108         if (!block_fw_in_parent_ns) {
 109                 if (mount("test", "/lib/firmware", "tmpfs", MS_RDONLY, NULL) == -1)
 110                         die("blocking firmware in child ns failed\n");
 111         } else
 112                 umount("/lib/firmware");
 113
 114         trigger_fw(fw_name, sys_path);
 115
 116         exit(EXIT_SUCCESS);
 117 }
 118
 119 int main(int argc, char **argv)
 120 {
 121         const char *fw_name = "test-firmware.bin";
 122         char *sys_path;
 123         if (argc != 2)
 124                 die("usage: %s sys_path\n", argv[0]);
 125
 126         /* Mount tmpfs to /lib/firmware so we don't have to assume
 127            that it is writable for us.*/
 128         if (mount("test", "/lib/firmware", "tmpfs", 0, NULL) == -1)
 129                 die("mounting tmpfs to /lib/firmware failed\n");
 130
 131         sys_path = argv[1];
 132         asprintf(&fw_path, "/lib/firmware/%s", fw_name);
 133
 134         setup_fw(fw_path);
 135
 136         setvbuf(stdout, NULL, _IONBF, 0);
 137         /* Positive case: firmware in PID1 mount namespace */
 138         printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
 139         if (!test_fw_in_ns(fw_name, sys_path, false))
 140                 die("error: failed to access firmware\n");
 141
 142         /* Negative case: firmware in child mount namespace, expected to fail */
 143         printf("Testing with firmware in child namespace\n");
 144         if (test_fw_in_ns(fw_name, sys_path, true))
 145                 die("error: firmware access did not fail\n");
 146
 147         unlink(fw_path);
 148         free(fw_path);
 149         umount("/lib/firmware");
 150         exit(EXIT_SUCCESS);
 151 }