1 // SPDX-License-Identifier: GPL-2.0 2 #define _GNU_SOURCE 3 #define __SANE_USERSPACE_TYPES__ // Use ll64 4 5 #include <inttypes.h> 6 #include <unistd.h> 7 #include <stdio.h> 8 9 #include <linux/unistd.h> 10 #include <linux/types.h> 11 #include <linux/mount.h> 12 #include <sys/syscall.h> 13 #include <sys/stat.h> 14 #include <sys/mman.h> 15 #include <sched.h> 16 #include <fcntl.h> 17 18 #include "../../kselftest.h" 19 #include "log.h" 20 #include "wrappers.h" 21 22 static long get_file_dev_and_inode(void *addr, struct statx *stx) 23 { 24 char buf[4096]; 25 FILE *mapf; 26 27 mapf = fopen("/proc/self/maps", "r"); 28 if (mapf == NULL) 29 return pr_perror("fopen(/proc/self/maps)"); 30 31 while (fgets(buf, sizeof(buf), mapf)) { 32 unsigned long start, end; 33 uint32_t maj, min; 34 __u64 ino; 35 36 if (sscanf(buf, "%lx-%lx %*s %*s %x:%x %llu", 37 &start, &end, &maj, &min, &ino) != 5) 38 return pr_perror("unable to parse: %s", buf); 39 if (start == (unsigned long)addr) { 40 stx->stx_dev_major = maj; 41 stx->stx_dev_minor = min; 42 stx->stx_ino = ino; 43 return 0; 44 } 45 } 46 47 return pr_err("unable to find the mapping"); 48 } 49 50 static int ovl_mount(void) 51 { 52 int tmpfs, fsfd, ovl; 53 54 fsfd = sys_fsopen("tmpfs", 0); 55 if (fsfd == -1) 56 return pr_perror("fsopen(tmpfs)"); 57 58 if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) 59 return pr_perror("FSCONFIG_CMD_CREATE"); 60 61 tmpfs = sys_fsmount(fsfd, 0, 0); 62 if (tmpfs == -1) 63 return pr_perror("fsmount"); 64 65 close(fsfd); 66 67 /* overlayfs can't be constructed on top of a detached mount. */ 68 if (sys_move_mount(tmpfs, "", AT_FDCWD, "/tmp", MOVE_MOUNT_F_EMPTY_PATH)) 69 return pr_perror("move_mount"); 70 close(tmpfs); 71 72 if (mkdir("/tmp/w", 0755) == -1 || 73 mkdir("/tmp/u", 0755) == -1 || 74 mkdir("/tmp/l", 0755) == -1) 75 return pr_perror("mkdir"); 76 77 fsfd = sys_fsopen("overlay", 0); 78 if (fsfd == -1) 79 return pr_perror("fsopen(overlay)"); 80 if (sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "test", 0) == -1 || 81 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "lowerdir", "/tmp/l", 0) == -1 || 82 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "upperdir", "/tmp/u", 0) == -1 || 83 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "workdir", "/tmp/w", 0) == -1) 84 return pr_perror("fsconfig"); 85 if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) 86 return pr_perror("fsconfig"); 87 ovl = sys_fsmount(fsfd, 0, 0); 88 if (ovl == -1) 89 return pr_perror("fsmount"); 90 91 return ovl; 92 } 93 94 /* 95 * Check that the file device and inode shown in /proc/pid/maps match values 96 * returned by stat(2). 97 */ 98 static int test(void) 99 { 100 struct statx stx, mstx; 101 int ovl, fd; 102 void *addr; 103 104 ovl = ovl_mount(); 105 if (ovl == -1) 106 return -1; 107 108 fd = openat(ovl, "test", O_RDWR | O_CREAT, 0644); 109 if (fd == -1) 110 return pr_perror("openat"); 111 112 addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0); 113 if (addr == MAP_FAILED) 114 return pr_perror("mmap"); 115 116 if (get_file_dev_and_inode(addr, &mstx)) 117 return -1; 118 if (statx(fd, "", AT_EMPTY_PATH | AT_STATX_SYNC_AS_STAT, STATX_INO, &stx)) 119 return pr_perror("statx"); 120 121 if (stx.stx_dev_major != mstx.stx_dev_major || 122 stx.stx_dev_minor != mstx.stx_dev_minor || 123 stx.stx_ino != mstx.stx_ino) 124 return pr_fail("unmatched dev:ino %x:%x:%llx (expected %x:%x:%llx)\n", 125 mstx.stx_dev_major, mstx.stx_dev_minor, mstx.stx_ino, 126 stx.stx_dev_major, stx.stx_dev_minor, stx.stx_ino); 127 128 ksft_test_result_pass("devices are matched\n"); 129 return 0; 130 } 131 132 int main(int argc, char **argv) 133 { 134 int fsfd; 135 136 fsfd = sys_fsopen("overlay", 0); 137 if (fsfd == -1) { 138 ksft_test_result_skip("unable to create overlay mount\n"); 139 return 1; 140 } 141 close(fsfd); 142 143 /* Create a new mount namespace to not care about cleaning test mounts. */ 144 if (unshare(CLONE_NEWNS) == -1) { 145 ksft_test_result_skip("unable to create a new mount namespace\n"); 146 return 1; 147 } 148 if (sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) == -1) { 149 pr_perror("mount"); 150 return 1; 151 } 152 153 ksft_set_plan(1); 154 155 if (test()) 156 return 1; 157 158 ksft_exit_pass(); 159 return 0; 160 } 161