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 21 static int sys_fsopen(const char *fsname, unsigned int flags) 22 { 23 return syscall(__NR_fsopen, fsname, flags); 24 } 25 26 static int sys_fsconfig(int fd, unsigned int cmd, const char *key, const char *value, int aux) 27 { 28 return syscall(__NR_fsconfig, fd, cmd, key, value, aux); 29 } 30 31 static int sys_fsmount(int fd, unsigned int flags, unsigned int attr_flags) 32 { 33 return syscall(__NR_fsmount, fd, flags, attr_flags); 34 } 35 static int sys_mount(const char *src, const char *tgt, const char *fst, 36 unsigned long flags, const void *data) 37 { 38 return syscall(__NR_mount, src, tgt, fst, flags, data); 39 } 40 static int sys_move_mount(int from_dfd, const char *from_pathname, 41 int to_dfd, const char *to_pathname, 42 unsigned int flags) 43 { 44 return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd, to_pathname, flags); 45 } 46 47 static long get_file_dev_and_inode(void *addr, struct statx *stx) 48 { 49 char buf[4096]; 50 FILE *mapf; 51 52 mapf = fopen("/proc/self/maps", "r"); 53 if (mapf == NULL) 54 return pr_perror("fopen(/proc/self/maps)"); 55 56 while (fgets(buf, sizeof(buf), mapf)) { 57 unsigned long start, end; 58 uint32_t maj, min; 59 __u64 ino; 60 61 if (sscanf(buf, "%lx-%lx %*s %*s %x:%x %llu", 62 &start, &end, &maj, &min, &ino) != 5) 63 return pr_perror("unable to parse: %s", buf); 64 if (start == (unsigned long)addr) { 65 stx->stx_dev_major = maj; 66 stx->stx_dev_minor = min; 67 stx->stx_ino = ino; 68 return 0; 69 } 70 } 71 72 return pr_err("unable to find the mapping"); 73 } 74 75 static int ovl_mount(void) 76 { 77 int tmpfs, fsfd, ovl; 78 79 fsfd = sys_fsopen("tmpfs", 0); 80 if (fsfd == -1) 81 return pr_perror("fsopen(tmpfs)"); 82 83 if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) 84 return pr_perror("FSCONFIG_CMD_CREATE"); 85 86 tmpfs = sys_fsmount(fsfd, 0, 0); 87 if (tmpfs == -1) 88 return pr_perror("fsmount"); 89 90 close(fsfd); 91 92 /* overlayfs can't be constructed on top of a detached mount. */ 93 if (sys_move_mount(tmpfs, "", AT_FDCWD, "/tmp", MOVE_MOUNT_F_EMPTY_PATH)) 94 return pr_perror("move_mount"); 95 close(tmpfs); 96 97 if (mkdir("/tmp/w", 0755) == -1 || 98 mkdir("/tmp/u", 0755) == -1 || 99 mkdir("/tmp/l", 0755) == -1) 100 return pr_perror("mkdir"); 101 102 fsfd = sys_fsopen("overlay", 0); 103 if (fsfd == -1) 104 return pr_perror("fsopen(overlay)"); 105 if (sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "test", 0) == -1 || 106 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "lowerdir", "/tmp/l", 0) == -1 || 107 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "upperdir", "/tmp/u", 0) == -1 || 108 sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "workdir", "/tmp/w", 0) == -1) 109 return pr_perror("fsconfig"); 110 if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) 111 return pr_perror("fsconfig"); 112 ovl = sys_fsmount(fsfd, 0, 0); 113 if (ovl == -1) 114 return pr_perror("fsmount"); 115 116 return ovl; 117 } 118 119 /* 120 * Check that the file device and inode shown in /proc/pid/maps match values 121 * returned by stat(2). 122 */ 123 static int test(void) 124 { 125 struct statx stx, mstx; 126 int ovl, fd; 127 void *addr; 128 129 ovl = ovl_mount(); 130 if (ovl == -1) 131 return -1; 132 133 fd = openat(ovl, "test", O_RDWR | O_CREAT, 0644); 134 if (fd == -1) 135 return pr_perror("openat"); 136 137 addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0); 138 if (addr == MAP_FAILED) 139 return pr_perror("mmap"); 140 141 if (get_file_dev_and_inode(addr, &mstx)) 142 return -1; 143 if (statx(fd, "", AT_EMPTY_PATH | AT_STATX_SYNC_AS_STAT, STATX_INO, &stx)) 144 return pr_perror("statx"); 145 146 if (stx.stx_dev_major != mstx.stx_dev_major || 147 stx.stx_dev_minor != mstx.stx_dev_minor || 148 stx.stx_ino != mstx.stx_ino) 149 return pr_fail("unmatched dev:ino %x:%x:%llx (expected %x:%x:%llx)\n", 150 mstx.stx_dev_major, mstx.stx_dev_minor, mstx.stx_ino, 151 stx.stx_dev_major, stx.stx_dev_minor, stx.stx_ino); 152 153 ksft_test_result_pass("devices are matched\n"); 154 return 0; 155 } 156 157 int main(int argc, char **argv) 158 { 159 int fsfd; 160 161 fsfd = sys_fsopen("overlay", 0); 162 if (fsfd == -1) { 163 ksft_test_result_skip("unable to create overlay mount\n"); 164 return 1; 165 } 166 close(fsfd); 167 168 /* Create a new mount namespace to not care about cleaning test mounts. */ 169 if (unshare(CLONE_NEWNS) == -1) { 170 ksft_test_result_skip("unable to create a new mount namespace\n"); 171 return 1; 172 } 173 if (sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) == -1) { 174 pr_perror("mount"); 175 return 1; 176 } 177 178 ksft_set_plan(1); 179 180 if (test()) 181 return 1; 182 183 ksft_exit_pass(); 184 return 0; 185 } 186