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Message-ID: <20231211193048.580691-2-avagin@google.com>
Date: Mon, 11 Dec 2023 11:30:48 -0800
From: Andrei Vagin <avagin@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Andrei Vagin <avagin@...gle.com>,
Amir Goldstein <amir73il@...il.com>,
Alexander Mikhalitsyn <alexander@...alicyn.com>
Subject: [PATCH 2/2] selftests/overlayfs: verify device and inode numbers in /proc/pid/maps
When mapping a file on overlayfs, the file stored in ->vm_file is a
backing file whose f_inode is on the underlying filesystem. We need to
verify that /proc/pid/maps contains numbers of the overlayfs file, but
not its backing file.
Cc: Amir Goldstein <amir73il@...il.com>
Cc: Alexander Mikhalitsyn <alexander@...alicyn.com>
Signed-off-by: Andrei Vagin <avagin@...gle.com>
---
tools/testing/selftests/Makefile | 1 +
.../filesystems/overlayfs/.gitignore | 2 +
.../selftests/filesystems/overlayfs/Makefile | 7 +
.../filesystems/overlayfs/dev_in_maps.c | 182 ++++++++++++++++++
.../selftests/filesystems/overlayfs/log.h | 26 +++
5 files changed, 218 insertions(+)
create mode 100644 tools/testing/selftests/filesystems/overlayfs/.gitignore
create mode 100644 tools/testing/selftests/filesystems/overlayfs/Makefile
create mode 100644 tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
create mode 100644 tools/testing/selftests/filesystems/overlayfs/log.h
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 3b2061d1c1a5..0939a40abb28 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -26,6 +26,7 @@ TARGETS += filesystems
TARGETS += filesystems/binderfs
TARGETS += filesystems/epoll
TARGETS += filesystems/fat
+TARGETS += filesystems/overlayfs
TARGETS += firmware
TARGETS += fpu
TARGETS += ftrace
diff --git a/tools/testing/selftests/filesystems/overlayfs/.gitignore b/tools/testing/selftests/filesystems/overlayfs/.gitignore
new file mode 100644
index 000000000000..52ae618fdd98
--- /dev/null
+++ b/tools/testing/selftests/filesystems/overlayfs/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+dev_in_maps
diff --git a/tools/testing/selftests/filesystems/overlayfs/Makefile b/tools/testing/selftests/filesystems/overlayfs/Makefile
new file mode 100644
index 000000000000..56b2b48a765b
--- /dev/null
+++ b/tools/testing/selftests/filesystems/overlayfs/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_GEN_PROGS := dev_in_maps
+
+CFLAGS := -Wall -Werror
+
+include ../../lib.mk
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..08497c2e10a3
--- /dev/null
+++ b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
@@ -0,0 +1,182 @@
+// 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/mount.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_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 %llx",
+ &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 (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;
+}
diff --git a/tools/testing/selftests/filesystems/overlayfs/log.h b/tools/testing/selftests/filesystems/overlayfs/log.h
new file mode 100644
index 000000000000..db64df2a8483
--- /dev/null
+++ b/tools/testing/selftests/filesystems/overlayfs/log.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __SELFTEST_TIMENS_LOG_H__
+#define __SELFTEST_TIMENS_LOG_H__
+
+#define pr_msg(fmt, lvl, ...) \
+ ksft_print_msg("[%s] (%s:%d)\t" fmt "\n", \
+ lvl, __FILE__, __LINE__, ##__VA_ARGS__)
+
+#define pr_p(func, fmt, ...) func(fmt ": %m", ##__VA_ARGS__)
+
+#define pr_err(fmt, ...) \
+ ({ \
+ ksft_test_result_error(fmt "\n", ##__VA_ARGS__); \
+ -1; \
+ })
+
+#define pr_fail(fmt, ...) \
+ ({ \
+ ksft_test_result_fail(fmt, ##__VA_ARGS__); \
+ -1; \
+ })
+
+#define pr_perror(fmt, ...) pr_p(pr_err, fmt, ##__VA_ARGS__)
+
+#endif
--
2.43.0.472.g3155946c3a-goog
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