LXR linux/tools/testing/selftests/firmware/fw

   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
  24static char *fw_path = NULL;
  25
  26static 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
  39static 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
  52static 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
  67static 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;
  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
 119int 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        if (asprintf(&fw_path, "/lib/firmware/%s", fw_name) < 0)
 133                die("error: failed to build full fw_path\n");
 134
 135        setup_fw(fw_path);
 136
 137        setvbuf(stdout, NULL, _IONBF, 0);
 138        /* Positive case: firmware in PID1 mount namespace */
 139        printf("Testing with firmware in parent namespace (assumed to be same file system as PID1)\n");
 140        if (!test_fw_in_ns(fw_name, sys_path, false))
 141                die("error: failed to access firmware\n");
 142
 143        /* Negative case: firmware in child mount namespace, expected to fail */
 144        printf("Testing with firmware in child namespace\n");
 145        if (test_fw_in_ns(fw_name, sys_path, true))
 146                die("error: firmware access did not fail\n");
 147
 148        unlink(fw_path);
 149        free(fw_path);
 150        umount("/lib/firmware");
 151        exit(EXIT_SUCCESS);
 152}
 153