On Fri, Oct 11, 2024 at 11:46 PM Christian Brauner <brauner@xxxxxxxxxx> wrote:
>
> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Very cool!
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> .../selftests/filesystems/overlayfs/.gitignore | 1 +
> .../selftests/filesystems/overlayfs/Makefile | 2 +-
> .../filesystems/overlayfs/set_layers_via_fds.c | 122 +++++++++++++++++++++
> .../selftests/filesystems/overlayfs/wrappers.h | 4 +
> 4 files changed, 128 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/filesystems/overlayfs/.gitignore b/tools/testing/selftests/filesystems/overlayfs/.gitignore
> index 52ae618fdd980ee22424d35d79f077077b132401..e23a18c8b37f2cdbb121496b1df1faffd729ad79 100644
> --- a/tools/testing/selftests/filesystems/overlayfs/.gitignore
> +++ b/tools/testing/selftests/filesystems/overlayfs/.gitignore
> @@ -1,2 +1,3 @@
> # SPDX-License-Identifier: GPL-2.0-only
> dev_in_maps
> +set_layers_via_fds
> diff --git a/tools/testing/selftests/filesystems/overlayfs/Makefile b/tools/testing/selftests/filesystems/overlayfs/Makefile
> index 56b2b48a765b1d6706faee14616597ed0315f267..e8d1adb021af44588dd7af1049de66833bb584ce 100644
> --- a/tools/testing/selftests/filesystems/overlayfs/Makefile
> +++ b/tools/testing/selftests/filesystems/overlayfs/Makefile
> @@ -1,6 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
>
> -TEST_GEN_PROGS := dev_in_maps
> +TEST_GEN_PROGS := dev_in_maps set_layers_via_fds
>
> CFLAGS := -Wall -Werror
>
> diff --git a/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..d3b497eea5e5c9f718caa4957f7fec7c40970502
> --- /dev/null
> +++ b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c
> @@ -0,0 +1,122 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE
> +#define __SANE_USERSPACE_TYPES__ // Use ll64
> +
> +#include <fcntl.h>
> +#include <sched.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <sys/stat.h>
> +#include <sys/mount.h>
> +#include <unistd.h>
> +
> +#include "../../kselftest_harness.h"
> +#include "log.h"
> +#include "wrappers.h"
> +
> +FIXTURE(set_layers_via_fds) {
> +};
> +
> +FIXTURE_SETUP(set_layers_via_fds)
> +{
> + ASSERT_EQ(mkdir("/set_layers_via_fds", 0755), 0);
> +}
> +
> +FIXTURE_TEARDOWN(set_layers_via_fds)
> +{
> + umount2("/set_layers_via_fds", 0);
> + ASSERT_EQ(rmdir("/set_layers_via_fds"), 0);
> +}
> +
> +TEST_F(set_layers_via_fds, set_layers_via_fds)
> +{
> + int fd_context, fd_tmpfs, fd_overlay;
> + int layer_fds[5] = { -EBADF, -EBADF, -EBADF, -EBADF, -EBADF };
> + bool layers_found[5] = { false, false, false, false, false };
> + size_t len = 0;
> + char *line = NULL;
> + FILE *f_mountinfo;
> +
> + ASSERT_EQ(unshare(CLONE_NEWNS), 0);
> + ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0);
> +
> + fd_context = sys_fsopen("tmpfs", 0);
> + ASSERT_GE(fd_context, 0);
> +
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
> + fd_tmpfs = sys_fsmount(fd_context, 0, 0);
> + ASSERT_GE(fd_tmpfs, 0);
> + ASSERT_EQ(close(fd_context), 0);
> +
> + ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0);
> + ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0);
> + ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0);
> + ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0);
> + ASSERT_EQ(mkdirat(fd_tmpfs, "l3", 0755), 0);
> +
> + layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY);
> + ASSERT_GE(layer_fds[0], 0);
> +
> + layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY);
> + ASSERT_GE(layer_fds[1], 0);
> +
> + layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY);
> + ASSERT_GE(layer_fds[2], 0);
> +
> + layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY);
> + ASSERT_GE(layer_fds[3], 0);
> +
> + layer_fds[4] = openat(fd_tmpfs, "l3", O_DIRECTORY);
> + ASSERT_GE(layer_fds[4], 0);
> +
> + ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0);
> + ASSERT_EQ(close(fd_tmpfs), 0);
> +
> + fd_context = sys_fsopen("overlay", 0);
> + ASSERT_GE(fd_context, 0);
> +
> + ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0);
> +
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir", NULL, layer_fds[0]), 0);
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir", NULL, layer_fds[1]), 0);
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0);
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0);
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[4]), 0);
> +
> + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0);
> +
> + fd_overlay = sys_fsmount(fd_context, 0, 0);
> + ASSERT_GE(fd_overlay, 0);
> +
> + ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0);
> +
> + f_mountinfo = fopen("/proc/self/mountinfo", "r");
> + ASSERT_NE(f_mountinfo, NULL);
> +
> + while (getline(&line, &len, f_mountinfo) != -1) {
> + char *haystack = line;
> +
> + if (strstr(haystack, "workdir=/tmp/w"))
> + layers_found[0] = true;
> + if (strstr(haystack, "upperdir=/tmp/u"))
> + layers_found[1] = true;
> + if (strstr(haystack, "lowerdir+=/tmp/l1"))
> + layers_found[2] = true;
> + if (strstr(haystack, "lowerdir+=/tmp/l2"))
> + layers_found[3] = true;
> + if (strstr(haystack, "lowerdir+=/tmp/l3"))
> + layers_found[4] = true;
> + }
> + free(line);
> +
> + for (int i = 0; i < 5; i++) {
> + ASSERT_EQ(layers_found[i], true);
> + ASSERT_EQ(close(layer_fds[i]), 0);
> + }
> +
> + ASSERT_EQ(close(fd_context), 0);
> + ASSERT_EQ(close(fd_overlay), 0);
> + ASSERT_EQ(fclose(f_mountinfo), 0);
> +}
> +
> +TEST_HARNESS_MAIN
> diff --git a/tools/testing/selftests/filesystems/overlayfs/wrappers.h b/tools/testing/selftests/filesystems/overlayfs/wrappers.h
> index 4f99e10f7f018fd9a7be5263f68d34807da4c53c..071b95fd2ac0ad7b02d90e8e89df73fd27be69c3 100644
> --- a/tools/testing/selftests/filesystems/overlayfs/wrappers.h
> +++ b/tools/testing/selftests/filesystems/overlayfs/wrappers.h
> @@ -32,6 +32,10 @@ static inline int sys_mount(const char *src, const char *tgt, const char *fst,
> return syscall(__NR_mount, src, tgt, fst, flags, data);
> }
>
> +#ifndef MOVE_MOUNT_F_EMPTY_PATH
> +#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
> +#endif
> +
> static inline int sys_move_mount(int from_dfd, const char *from_pathname,
> int to_dfd, const char *to_pathname,
> unsigned int flags)
>
> --
> 2.45.2
>
