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// 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;
}
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