diff options
Diffstat (limited to 'tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c')
| -rw-r--r-- | tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c new file mode 100644 index 000000000000..759f86e7d263 --- /dev/null +++ b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include <inttypes.h> +#include <unistd.h> +#include <stdio.h> + +#include <linux/unistd.h> +#include <linux/types.h> +#include <linux/mount.h> +#include <sys/syscall.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <sched.h> +#include <fcntl.h> + +#include "../../kselftest.h" +#include "log.h" + +static int sys_fsopen(const char *fsname, unsigned int flags) +{ + return syscall(__NR_fsopen, fsname, flags); +} + +static int sys_fsconfig(int fd, unsigned int cmd, const char *key, const char *value, int aux) +{ + return syscall(__NR_fsconfig, fd, cmd, key, value, aux); +} + +static int sys_fsmount(int fd, unsigned int flags, unsigned int attr_flags) +{ + return syscall(__NR_fsmount, fd, flags, attr_flags); +} +static int sys_mount(const char *src, const char *tgt, const char *fst, + unsigned long flags, const void *data) +{ + return syscall(__NR_mount, src, tgt, fst, flags, data); +} +static int sys_move_mount(int from_dfd, const char *from_pathname, + int to_dfd, const char *to_pathname, + unsigned int flags) +{ + return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd, to_pathname, flags); +} + +static long get_file_dev_and_inode(void *addr, struct statx *stx) +{ + char buf[4096]; + FILE *mapf; + + mapf = fopen("/proc/self/maps", "r"); + if (mapf == NULL) + return pr_perror("fopen(/proc/self/maps)"); + + while (fgets(buf, sizeof(buf), mapf)) { + unsigned long start, end; + uint32_t maj, min; + __u64 ino; + + if (sscanf(buf, "%lx-%lx %*s %*s %x:%x %llu", + &start, &end, &maj, &min, &ino) != 5) + return pr_perror("unable to parse: %s", buf); + if (start == (unsigned long)addr) { + stx->stx_dev_major = maj; + stx->stx_dev_minor = min; + stx->stx_ino = ino; + return 0; + } + } + + return pr_err("unable to find the mapping"); +} + +static int ovl_mount(void) +{ + int tmpfs, fsfd, ovl; + + fsfd = sys_fsopen("tmpfs", 0); + if (fsfd == -1) + return pr_perror("fsopen(tmpfs)"); + + if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) + return pr_perror("FSCONFIG_CMD_CREATE"); + + tmpfs = sys_fsmount(fsfd, 0, 0); + if (tmpfs == -1) + return pr_perror("fsmount"); + + close(fsfd); + + /* overlayfs can't be constructed on top of a detached mount. */ + if (sys_move_mount(tmpfs, "", AT_FDCWD, "/tmp", MOVE_MOUNT_F_EMPTY_PATH)) + return pr_perror("move_mount"); + close(tmpfs); + + if (mkdir("/tmp/w", 0755) == -1 || + mkdir("/tmp/u", 0755) == -1 || + mkdir("/tmp/l", 0755) == -1) + return pr_perror("mkdir"); + + fsfd = sys_fsopen("overlay", 0); + if (fsfd == -1) + return pr_perror("fsopen(overlay)"); + if (sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "test", 0) == -1 || + sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "lowerdir", "/tmp/l", 0) == -1 || + sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "upperdir", "/tmp/u", 0) == -1 || + sys_fsconfig(fsfd, FSCONFIG_SET_STRING, "workdir", "/tmp/w", 0) == -1) + return pr_perror("fsconfig"); + if (sys_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) == -1) + return pr_perror("fsconfig"); + ovl = sys_fsmount(fsfd, 0, 0); + if (ovl == -1) + return pr_perror("fsmount"); + + return ovl; +} + +/* + * Check that the file device and inode shown in /proc/pid/maps match values + * returned by stat(2). + */ +static int test(void) +{ + struct statx stx, mstx; + int ovl, fd; + void *addr; + + ovl = ovl_mount(); + if (ovl == -1) + return -1; + + fd = openat(ovl, "test", O_RDWR | O_CREAT, 0644); + if (fd == -1) + return pr_perror("openat"); + + addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0); + if (addr == MAP_FAILED) + return pr_perror("mmap"); + + if (get_file_dev_and_inode(addr, &mstx)) + return -1; + if (statx(fd, "", AT_EMPTY_PATH | AT_STATX_SYNC_AS_STAT, STATX_INO, &stx)) + return pr_perror("statx"); + + if (stx.stx_dev_major != mstx.stx_dev_major || + stx.stx_dev_minor != mstx.stx_dev_minor || + stx.stx_ino != mstx.stx_ino) + return pr_fail("unmatched dev:ino %x:%x:%llx (expected %x:%x:%llx)\n", + mstx.stx_dev_major, mstx.stx_dev_minor, mstx.stx_ino, + stx.stx_dev_major, stx.stx_dev_minor, stx.stx_ino); + + ksft_test_result_pass("devices are matched\n"); + return 0; +} + +int main(int argc, char **argv) +{ + int fsfd; + + fsfd = sys_fsopen("overlay", 0); + if (fsfd == -1) { + ksft_test_result_skip("unable to create overlay mount\n"); + return 1; + } + close(fsfd); + + /* Create a new mount namespace to not care about cleaning test mounts. */ + if (unshare(CLONE_NEWNS) == -1) { + ksft_test_result_skip("unable to create a new mount namespace\n"); + return 1; + } + if (sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) == -1) { + pr_perror("mount"); + return 1; + } + + ksft_set_plan(1); + + if (test()) + return 1; + + ksft_exit_pass(); + return 0; +} |