From 781091f3f59456e881170570b2304ec11e9ce7e0 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 9 May 2025 15:32:40 +0200 Subject: [PATCH] selftests/fs/mount-notify: add a test variant running inside userns unshare userns in addition to mntns and verify that: 1. watching tmpfs mounted inside userns is allowed with any mark type 2. watching orig root with filesystem mark type is not allowed 3. watching mntns of orig userns is not allowed 4. watching mntns in userns where fanotify_init was called is allowed mount events are only tested with the last case of mntns mark. Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/20250509133240.529330-9-amir73il@gmail.com Reviewed-by: Christian Brauner Signed-off-by: Christian Brauner --- .../filesystems/mount-notify/.gitignore | 1 + .../filesystems/mount-notify/Makefile | 3 +- .../mount-notify/mount-notify_test_ns.c | 557 ++++++++++++++++++ 3 files changed, 560 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c diff --git a/tools/testing/selftests/filesystems/mount-notify/.gitignore b/tools/testing/selftests/filesystems/mount-notify/.gitignore index 82a4846cbc4b2..124339ea78451 100644 --- a/tools/testing/selftests/filesystems/mount-notify/.gitignore +++ b/tools/testing/selftests/filesystems/mount-notify/.gitignore @@ -1,2 +1,3 @@ # SPDX-License-Identifier: GPL-2.0-only /*_test +/*_test_ns diff --git a/tools/testing/selftests/filesystems/mount-notify/Makefile b/tools/testing/selftests/filesystems/mount-notify/Makefile index 55a2e5399e8a3..836a4eb7be062 100644 --- a/tools/testing/selftests/filesystems/mount-notify/Makefile +++ b/tools/testing/selftests/filesystems/mount-notify/Makefile @@ -3,8 +3,9 @@ CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS += -lcap -TEST_GEN_PROGS := mount-notify_test +TEST_GEN_PROGS := mount-notify_test mount-notify_test_ns include ../../lib.mk $(OUTPUT)/mount-notify_test: ../utils.c +$(OUTPUT)/mount-notify_test_ns: ../utils.c diff --git a/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c new file mode 100644 index 0000000000000..090a5ca65004a --- /dev/null +++ b/tools/testing/selftests/filesystems/mount-notify/mount-notify_test_ns.c @@ -0,0 +1,557 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +// Copyright (c) 2025 Miklos Szeredi + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../../kselftest_harness.h" +#include "../../pidfd/pidfd.h" +#include "../statmount/statmount.h" +#include "../utils.h" + +// Needed for linux/fanotify.h +#ifndef __kernel_fsid_t +typedef struct { + int val[2]; +} __kernel_fsid_t; +#endif + +#include + +static const char root_mntpoint_templ[] = "/tmp/mount-notify_test_root.XXXXXX"; + +static const int mark_types[] = { + FAN_MARK_FILESYSTEM, + FAN_MARK_MOUNT, + FAN_MARK_INODE +}; + +static const int mark_cmds[] = { + FAN_MARK_ADD, + FAN_MARK_REMOVE, + FAN_MARK_FLUSH +}; + +#define NUM_FAN_FDS ARRAY_SIZE(mark_cmds) + +FIXTURE(fanotify) { + int fan_fd[NUM_FAN_FDS]; + char buf[256]; + unsigned int rem; + void *next; + char root_mntpoint[sizeof(root_mntpoint_templ)]; + int orig_root; + int orig_ns_fd; + int ns_fd; + uint64_t root_id; +}; + +FIXTURE_SETUP(fanotify) +{ + int i, ret; + + self->orig_ns_fd = open("/proc/self/ns/mnt", O_RDONLY); + ASSERT_GE(self->orig_ns_fd, 0); + + ret = setup_userns(); + ASSERT_EQ(ret, 0); + + self->ns_fd = open("/proc/self/ns/mnt", O_RDONLY); + ASSERT_GE(self->ns_fd, 0); + + strcpy(self->root_mntpoint, root_mntpoint_templ); + ASSERT_NE(mkdtemp(self->root_mntpoint), NULL); + + self->orig_root = open("/", O_PATH | O_CLOEXEC); + ASSERT_GE(self->orig_root, 0); + + ASSERT_EQ(mount("tmpfs", self->root_mntpoint, "tmpfs", 0, NULL), 0); + + ASSERT_EQ(chroot(self->root_mntpoint), 0); + + ASSERT_EQ(chdir("/"), 0); + + ASSERT_EQ(mkdir("a", 0700), 0); + + ASSERT_EQ(mkdir("b", 0700), 0); + + self->root_id = get_unique_mnt_id("/"); + ASSERT_NE(self->root_id, 0); + + for (i = 0; i < NUM_FAN_FDS; i++) { + int fan_fd = fanotify_init(FAN_REPORT_FID, 0); + // Verify that watching tmpfs mounted inside userns is allowed + ret = fanotify_mark(fan_fd, FAN_MARK_ADD | mark_types[i], + FAN_OPEN, AT_FDCWD, "/"); + ASSERT_EQ(ret, 0); + // ...but watching entire orig root filesystem is not allowed + ret = fanotify_mark(fan_fd, FAN_MARK_ADD | FAN_MARK_FILESYSTEM, + FAN_OPEN, self->orig_root, "."); + ASSERT_NE(ret, 0); + close(fan_fd); + + self->fan_fd[i] = fanotify_init(FAN_REPORT_MNT | FAN_NONBLOCK, + 0); + ASSERT_GE(self->fan_fd[i], 0); + // Verify that watching mntns where group was created is allowed + ret = fanotify_mark(self->fan_fd[i], FAN_MARK_ADD | + FAN_MARK_MNTNS, + FAN_MNT_ATTACH | FAN_MNT_DETACH, + self->ns_fd, NULL); + ASSERT_EQ(ret, 0); + // ...but watching orig mntns is not allowed + ret = fanotify_mark(self->fan_fd[i], FAN_MARK_ADD | + FAN_MARK_MNTNS, + FAN_MNT_ATTACH | FAN_MNT_DETACH, + self->orig_ns_fd, NULL); + ASSERT_NE(ret, 0); + // On fd[0] we do an extra ADD that changes nothing. + // On fd[1]/fd[2] we REMOVE/FLUSH which removes the mark. + ret = fanotify_mark(self->fan_fd[i], mark_cmds[i] | + FAN_MARK_MNTNS, + FAN_MNT_ATTACH | FAN_MNT_DETACH, + self->ns_fd, NULL); + ASSERT_EQ(ret, 0); + } + + self->rem = 0; +} + +FIXTURE_TEARDOWN(fanotify) +{ + int i; + + ASSERT_EQ(self->rem, 0); + for (i = 0; i < NUM_FAN_FDS; i++) + close(self->fan_fd[i]); + + ASSERT_EQ(fchdir(self->orig_root), 0); + + ASSERT_EQ(chroot("."), 0); + + EXPECT_EQ(umount2(self->root_mntpoint, MNT_DETACH), 0); + EXPECT_EQ(chdir(self->root_mntpoint), 0); + EXPECT_EQ(chdir("/"), 0); + EXPECT_EQ(rmdir(self->root_mntpoint), 0); +} + +static uint64_t expect_notify(struct __test_metadata *const _metadata, + FIXTURE_DATA(fanotify) *self, + uint64_t *mask) +{ + struct fanotify_event_metadata *meta; + struct fanotify_event_info_mnt *mnt; + unsigned int thislen; + + if (!self->rem) { + ssize_t len; + int i; + + for (i = NUM_FAN_FDS - 1; i >= 0; i--) { + len = read(self->fan_fd[i], self->buf, + sizeof(self->buf)); + if (i > 0) { + // Groups 1,2 should get EAGAIN + ASSERT_EQ(len, -1); + ASSERT_EQ(errno, EAGAIN); + } else { + // Group 0 should get events + ASSERT_GT(len, 0); + } + } + + self->rem = len; + self->next = (void *) self->buf; + } + + meta = self->next; + ASSERT_TRUE(FAN_EVENT_OK(meta, self->rem)); + + thislen = meta->event_len; + self->rem -= thislen; + self->next += thislen; + + *mask = meta->mask; + thislen -= sizeof(*meta); + + mnt = ((void *) meta) + meta->event_len - thislen; + + ASSERT_EQ(thislen, sizeof(*mnt)); + + return mnt->mnt_id; +} + +static void expect_notify_n(struct __test_metadata *const _metadata, + FIXTURE_DATA(fanotify) *self, + unsigned int n, uint64_t mask[], uint64_t mnts[]) +{ + unsigned int i; + + for (i = 0; i < n; i++) + mnts[i] = expect_notify(_metadata, self, &mask[i]); +} + +static uint64_t expect_notify_mask(struct __test_metadata *const _metadata, + FIXTURE_DATA(fanotify) *self, + uint64_t expect_mask) +{ + uint64_t mntid, mask; + + mntid = expect_notify(_metadata, self, &mask); + ASSERT_EQ(expect_mask, mask); + + return mntid; +} + + +static void expect_notify_mask_n(struct __test_metadata *const _metadata, + FIXTURE_DATA(fanotify) *self, + uint64_t mask, unsigned int n, uint64_t mnts[]) +{ + unsigned int i; + + for (i = 0; i < n; i++) + mnts[i] = expect_notify_mask(_metadata, self, mask); +} + +static void verify_mount_ids(struct __test_metadata *const _metadata, + const uint64_t list1[], const uint64_t list2[], + size_t num) +{ + unsigned int i, j; + + // Check that neither list has any duplicates + for (i = 0; i < num; i++) { + for (j = 0; j < num; j++) { + if (i != j) { + ASSERT_NE(list1[i], list1[j]); + ASSERT_NE(list2[i], list2[j]); + } + } + } + // Check that all list1 memebers can be found in list2. Together with + // the above it means that the list1 and list2 represent the same sets. + for (i = 0; i < num; i++) { + for (j = 0; j < num; j++) { + if (list1[i] == list2[j]) + break; + } + ASSERT_NE(j, num); + } +} + +static void check_mounted(struct __test_metadata *const _metadata, + const uint64_t mnts[], size_t num) +{ + ssize_t ret; + uint64_t *list; + + list = malloc((num + 1) * sizeof(list[0])); + ASSERT_NE(list, NULL); + + ret = listmount(LSMT_ROOT, 0, 0, list, num + 1, 0); + ASSERT_EQ(ret, num); + + verify_mount_ids(_metadata, mnts, list, num); + + free(list); +} + +static void setup_mount_tree(struct __test_metadata *const _metadata, + int log2_num) +{ + int ret, i; + + ret = mount("", "/", NULL, MS_SHARED, NULL); + ASSERT_EQ(ret, 0); + + for (i = 0; i < log2_num; i++) { + ret = mount("/", "/", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + } +} + +TEST_F(fanotify, bind) +{ + int ret; + uint64_t mnts[2] = { self->root_id }; + + ret = mount("/", "/", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + mnts[1] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + ASSERT_NE(mnts[0], mnts[1]); + + check_mounted(_metadata, mnts, 2); + + // Cleanup + uint64_t detach_id; + ret = umount("/"); + ASSERT_EQ(ret, 0); + + detach_id = expect_notify_mask(_metadata, self, FAN_MNT_DETACH); + ASSERT_EQ(detach_id, mnts[1]); + + check_mounted(_metadata, mnts, 1); +} + +TEST_F(fanotify, move) +{ + int ret; + uint64_t mnts[2] = { self->root_id }; + uint64_t move_id; + + ret = mount("/", "/a", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + mnts[1] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + ASSERT_NE(mnts[0], mnts[1]); + + check_mounted(_metadata, mnts, 2); + + ret = move_mount(AT_FDCWD, "/a", AT_FDCWD, "/b", 0); + ASSERT_EQ(ret, 0); + + move_id = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH | FAN_MNT_DETACH); + ASSERT_EQ(move_id, mnts[1]); + + // Cleanup + ret = umount("/b"); + ASSERT_EQ(ret, 0); + + check_mounted(_metadata, mnts, 1); +} + +TEST_F(fanotify, propagate) +{ + const unsigned int log2_num = 4; + const unsigned int num = (1 << log2_num); + uint64_t mnts[num]; + + setup_mount_tree(_metadata, log2_num); + + expect_notify_mask_n(_metadata, self, FAN_MNT_ATTACH, num - 1, mnts + 1); + + mnts[0] = self->root_id; + check_mounted(_metadata, mnts, num); + + // Cleanup + int ret; + uint64_t mnts2[num]; + ret = umount2("/", MNT_DETACH); + ASSERT_EQ(ret, 0); + + ret = mount("", "/", NULL, MS_PRIVATE, NULL); + ASSERT_EQ(ret, 0); + + mnts2[0] = self->root_id; + expect_notify_mask_n(_metadata, self, FAN_MNT_DETACH, num - 1, mnts2 + 1); + verify_mount_ids(_metadata, mnts, mnts2, num); + + check_mounted(_metadata, mnts, 1); +} + +TEST_F(fanotify, fsmount) +{ + int ret, fs, mnt; + uint64_t mnts[2] = { self->root_id }; + + fs = fsopen("tmpfs", 0); + ASSERT_GE(fs, 0); + + ret = fsconfig(fs, FSCONFIG_CMD_CREATE, 0, 0, 0); + ASSERT_EQ(ret, 0); + + mnt = fsmount(fs, 0, 0); + ASSERT_GE(mnt, 0); + + close(fs); + + ret = move_mount(mnt, "", AT_FDCWD, "/a", MOVE_MOUNT_F_EMPTY_PATH); + ASSERT_EQ(ret, 0); + + close(mnt); + + mnts[1] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + ASSERT_NE(mnts[0], mnts[1]); + + check_mounted(_metadata, mnts, 2); + + // Cleanup + uint64_t detach_id; + ret = umount("/a"); + ASSERT_EQ(ret, 0); + + detach_id = expect_notify_mask(_metadata, self, FAN_MNT_DETACH); + ASSERT_EQ(detach_id, mnts[1]); + + check_mounted(_metadata, mnts, 1); +} + +TEST_F(fanotify, reparent) +{ + uint64_t mnts[6] = { self->root_id }; + uint64_t dmnts[3]; + uint64_t masks[3]; + unsigned int i; + int ret; + + // Create setup with a[1] -> b[2] propagation + ret = mount("/", "/a", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + ret = mount("", "/a", NULL, MS_SHARED, NULL); + ASSERT_EQ(ret, 0); + + ret = mount("/a", "/b", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + ret = mount("", "/b", NULL, MS_SLAVE, NULL); + ASSERT_EQ(ret, 0); + + expect_notify_mask_n(_metadata, self, FAN_MNT_ATTACH, 2, mnts + 1); + + check_mounted(_metadata, mnts, 3); + + // Mount on a[3], which is propagated to b[4] + ret = mount("/", "/a", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + expect_notify_mask_n(_metadata, self, FAN_MNT_ATTACH, 2, mnts + 3); + + check_mounted(_metadata, mnts, 5); + + // Mount on b[5], not propagated + ret = mount("/", "/b", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + mnts[5] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + + check_mounted(_metadata, mnts, 6); + + // Umount a[3], which is propagated to b[4], but not b[5] + // This will result in b[5] "falling" on b[2] + ret = umount("/a"); + ASSERT_EQ(ret, 0); + + expect_notify_n(_metadata, self, 3, masks, dmnts); + verify_mount_ids(_metadata, mnts + 3, dmnts, 3); + + for (i = 0; i < 3; i++) { + if (dmnts[i] == mnts[5]) { + ASSERT_EQ(masks[i], FAN_MNT_ATTACH | FAN_MNT_DETACH); + } else { + ASSERT_EQ(masks[i], FAN_MNT_DETACH); + } + } + + mnts[3] = mnts[5]; + check_mounted(_metadata, mnts, 4); + + // Cleanup + ret = umount("/b"); + ASSERT_EQ(ret, 0); + + ret = umount("/a"); + ASSERT_EQ(ret, 0); + + ret = umount("/b"); + ASSERT_EQ(ret, 0); + + expect_notify_mask_n(_metadata, self, FAN_MNT_DETACH, 3, dmnts); + verify_mount_ids(_metadata, mnts + 1, dmnts, 3); + + check_mounted(_metadata, mnts, 1); +} + +TEST_F(fanotify, rmdir) +{ + uint64_t mnts[3] = { self->root_id }; + int ret; + + ret = mount("/", "/a", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + ret = mount("/", "/a/b", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + expect_notify_mask_n(_metadata, self, FAN_MNT_ATTACH, 2, mnts + 1); + + check_mounted(_metadata, mnts, 3); + + ret = chdir("/a"); + ASSERT_EQ(ret, 0); + + ret = fork(); + ASSERT_GE(ret, 0); + + if (ret == 0) { + chdir("/"); + unshare(CLONE_NEWNS); + mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); + umount2("/a", MNT_DETACH); + // This triggers a detach in the other namespace + rmdir("/a"); + exit(0); + } + wait(NULL); + + expect_notify_mask_n(_metadata, self, FAN_MNT_DETACH, 2, mnts + 1); + check_mounted(_metadata, mnts, 1); + + // Cleanup + ret = chdir("/"); + ASSERT_EQ(ret, 0); +} + +TEST_F(fanotify, pivot_root) +{ + uint64_t mnts[3] = { self->root_id }; + uint64_t mnts2[3]; + int ret; + + ret = mount("tmpfs", "/a", "tmpfs", 0, NULL); + ASSERT_EQ(ret, 0); + + mnts[2] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + + ret = mkdir("/a/new", 0700); + ASSERT_EQ(ret, 0); + + ret = mkdir("/a/old", 0700); + ASSERT_EQ(ret, 0); + + ret = mount("/a", "/a/new", NULL, MS_BIND, NULL); + ASSERT_EQ(ret, 0); + + mnts[1] = expect_notify_mask(_metadata, self, FAN_MNT_ATTACH); + check_mounted(_metadata, mnts, 3); + + ret = syscall(SYS_pivot_root, "/a/new", "/a/new/old"); + ASSERT_EQ(ret, 0); + + expect_notify_mask_n(_metadata, self, FAN_MNT_ATTACH | FAN_MNT_DETACH, 2, mnts2); + verify_mount_ids(_metadata, mnts, mnts2, 2); + check_mounted(_metadata, mnts, 3); + + // Cleanup + ret = syscall(SYS_pivot_root, "/old", "/old/a/new"); + ASSERT_EQ(ret, 0); + + ret = umount("/a/new"); + ASSERT_EQ(ret, 0); + + ret = umount("/a"); + ASSERT_EQ(ret, 0); + + check_mounted(_metadata, mnts, 1); +} + +TEST_HARNESS_MAIN