diff --git a/fs/dcache.c b/fs/dcache.c index a66be85f9d01..f44c7b39c3b3 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1583,6 +1583,8 @@ EXPORT_SYMBOL(path_has_submounts); * * Only one of d_invalidate() and d_set_mounted() must succeed. For * this reason take rename_lock and d_lock on dentry and ancestors. + * Likewise for dont_mount() which marks a dentry that is being removed + * under d_lock. */ int d_set_mounted(struct dentry *dentry) { @@ -1599,7 +1601,7 @@ int d_set_mounted(struct dentry *dentry) spin_unlock(&p->d_lock); } spin_lock(&dentry->d_lock); - if (!d_unlinked(dentry)) { + if (!d_unlinked(dentry) && !cant_mount(dentry)) { ret = -EBUSY; if (!d_mountpoint(dentry)) { dentry->d_flags |= DCACHE_MOUNTED; diff --git a/fs/fs_context.c b/fs/fs_context.c index 23ad66cd94e1..a50584df97be 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -315,6 +315,10 @@ struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, unsigned int sb_flags, unsigned int sb_flags_mask) { + /* kernel-internal superblocks are nobody's to reconfigure */ + if (dentry->d_sb->s_flags & SB_NOUSER) + return ERR_PTR(-EINVAL); + return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags, sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE); } diff --git a/fs/fsopen.c b/fs/fsopen.c index 9d5a7a22b529..ae19e5136598 100644 --- a/fs/fsopen.c +++ b/fs/fsopen.c @@ -190,9 +190,6 @@ SYSCALL_DEFINE3(fspick, int, dfd, const char __user *, path, unsigned int, flags ret = -EINVAL; if (target.mnt->mnt_root != target.dentry) goto err_path; - /* kernel-internal superblocks are nobody's to reconfigure */ - if (target.dentry->d_sb->s_flags & SB_NOUSER) - goto err_path; fc = fs_context_for_reconfigure(target.dentry, 0, 0); if (IS_ERR(fc)) { diff --git a/fs/mount.h b/fs/mount.h index 85f136786bbc..2223fb141499 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -234,6 +234,9 @@ static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns) #ifdef CONFIG_FSNOTIFY static inline void mnt_notify_add(struct mount *m) { + /* queued already under this namespace_sem hold */ + if (!list_empty(&m->to_notify)) + return; /* Optimize the case where there are no watches */ if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) || (m->prev_ns && m->prev_ns->n_fsnotify_marks)) diff --git a/fs/namespace.c b/fs/namespace.c index 5b44eee28f39..fcf42f192aae 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -130,7 +130,6 @@ static void mnt_ns_release(struct mnt_namespace *ns) { /* keep alive for {list,stat}mount() */ if (ns && refcount_dec_and_test(&ns->passive)) { - fsnotify_mntns_delete(ns); put_user_ns(ns->user_ns); kfree(ns); } @@ -333,6 +332,9 @@ static struct mount *alloc_vfsmnt(const char *name) INIT_HLIST_NODE(&mnt->mnt_mp_list); INIT_HLIST_HEAD(&mnt->mnt_stuck_children); INIT_HLIST_NODE(&mnt->mnt_ns_visible); +#ifdef CONFIG_FSNOTIFY + INIT_LIST_HEAD(&mnt->to_notify); +#endif RB_CLEAR_NODE(&mnt->mnt_node); mnt->mnt.mnt_idmap = &nop_mnt_idmap; } @@ -2366,6 +2368,18 @@ bool has_locked_children(struct mount *mnt, struct dentry *dentry) return __has_locked_children(mnt, dentry); } +/* locks: namespace_shared && pinned(mnt) || mount_locked_reader */ +static bool __has_children(struct mount *mnt, struct dentry *dentry) +{ + struct mount *child; + + list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { + if (is_subdir(child->mnt_mountpoint, dentry)) + return true; + } + return false; +} + /* * Check that there aren't references to earlier/same mount namespaces in the * specified subtree. Such references can act as pins for mount namespaces @@ -2602,9 +2616,11 @@ static int attach_recursive_mnt(struct mount *source_mnt, * Preallocate a mountpoint in case the new mounts need to be * mounted beneath mounts on the same mountpoint. */ - for (top = source_mnt; unlikely(top->overmount); top = top->overmount) { + for (top = source_mnt; ; top = top->overmount) { if (!shorter && is_mnt_ns_file(top->mnt.mnt_root)) shorter = top->mnt_mp; + if (likely(!top->overmount)) + break; } err = get_mountpoint(top->mnt.mnt_root, &root); if (err) @@ -3010,6 +3026,10 @@ static struct mount *__do_loopback(const struct path *old_path, if (!may_copy_tree(old_path)) return ERR_PTR(-EINVAL); + /* a pseudo dentry is freed without an RCU delay, no walk may find it */ + if (old_path->dentry->d_flags & DCACHE_NORCU) + return ERR_PTR(-EINVAL); + if (recurse && !old->mnt_ns) return ERR_PTR(-EINVAL); @@ -3052,7 +3072,11 @@ static int do_loopback(const struct path *path, const char *old_name, if (IS_ERR(mnt)) return PTR_ERR(mnt); - err = graft_tree(mnt, &mp); + /* the copy may carry mount namespace files from below the source */ + if (recurse && !check_for_nsfs_mounts(mnt)) + err = -EINVAL; + else + err = graft_tree(mnt, &mp); if (err) { lock_mount_hash(); umount_tree(mnt, UMOUNT_SYNC); @@ -3134,12 +3158,18 @@ static struct mnt_namespace *create_new_namespace(struct path *path, struct mount *mnt; unsigned int copy_flags = 0; bool locked = false, recurse = flags & MOUNT_COPY_RECURSIVE; + bool foreign = user_ns != ns->user_ns; if (unlikely(!d_can_lookup(path->dentry))) return ERR_PTR(-ENOTDIR); - if (user_ns != ns->user_ns) - copy_flags |= CL_SLAVE; + /* + * Without privileges over the mount namespace the copy is made from + * nothing mounted below @path may be left out. It would reveal what + * it covers. That's what unshare() gives such a caller as well. + */ + if (foreign) + copy_flags |= CL_SLAVE | CL_COPY_UNBINDABLE; new_ns = alloc_mnt_ns(user_ns, false); if (IS_ERR(new_ns)) @@ -3173,10 +3203,14 @@ static struct mnt_namespace *create_new_namespace(struct path *path, /* * We don't emulate unshare()ing a mount namespace. We stick to * the restrictions of creating detached bind-mounts. It has a - * lot saner and simpler semantics. + * lot saner and simpler semantics. A caller without privileges + * over the mount namespace can't leave out any child though. */ if (flags & MOUNT_COPY_NEW) mnt = clone_mnt(real_mount(path->mnt), path->dentry, copy_flags); + else if (foreign && !recurse && + __has_children(real_mount(path->mnt), path->dentry)) + mnt = ERR_PTR(-EINVAL); else mnt = __do_loopback(path, recurse, copy_flags); scoped_guard(mount_writer) { @@ -3193,7 +3227,7 @@ static struct mnt_namespace *create_new_namespace(struct path *path, * of the real rootfs we created. */ attach_mnt(mnt, new_ns_root, mp.mp); - if (user_ns != ns->user_ns) + if (foreign) lock_mnt_tree(new_ns_root); } @@ -3984,6 +4018,11 @@ void mark_mounts_for_expiry(struct list_head *mounts) } while (!list_empty(&graveyard)) { mnt = list_first_entry(&graveyard, struct mount, mnt_expire); + /* an earlier umount_tree() may have moved a busy mount here */ + if (propagate_mount_busy(mnt, 1)) { + list_move(&mnt->mnt_expire, mounts); + continue; + } touch_mnt_namespace(mnt->mnt_ns); umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); } @@ -3991,17 +4030,37 @@ void mark_mounts_for_expiry(struct list_head *mounts) EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); +/* + * Unmount @mnt if it's a shrinkable mount without children that nobody uses. + * + * mount_lock must be held for write + */ +static bool shrink_submount(struct mount *mnt) +{ + if (propagate_mount_busy(mnt, 1)) + return false; + touch_mnt_namespace(mnt->mnt_ns); + umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); + return true; +} + /* * Ripoff of 'select_parent()' * - * search the list of submounts for a given mountpoint, and move any - * shrinkable submounts to the 'graveyard' list. + * unmount the shrinkable submounts of @parent that aren't busy, children + * before their parent, and say whether anything went + * + * The cursor into the children of @this_parent survives the umount of a + * child mount without child mounts. The mounts that get umounted together with + * it are located under receiving mounts of @this_parent and never under + * @this_parent itself. The one exception is @this_parent getting unmounted + * then the walk starts over. */ -static int select_submounts(struct mount *parent, struct list_head *graveyard) +static bool __shrink_submounts(struct mount *parent) { struct mount *this_parent = parent; struct list_head *next; - int found = 0; + bool shrunk = false; repeat: next = this_parent->mnt_mounts.next; @@ -4020,42 +4079,45 @@ resume: this_parent = mnt; goto repeat; } - - if (!propagate_mount_busy(mnt, 1)) { - list_move_tail(&mnt->mnt_expire, graveyard); - found++; - } + if (!shrink_submount(mnt)) + continue; + shrunk = true; + if (unlikely(this_parent->mnt.mnt_flags & MNT_UMOUNT)) + return true; } /* * All done at this level ... ascend and resume the search */ if (this_parent != parent) { - next = this_parent->mnt_child.next; - this_parent = this_parent->mnt_parent; + struct mount *mnt = this_parent; + + next = mnt->mnt_child.next; + this_parent = mnt->mnt_parent; + /* its children are gone, maybe it can go as well */ + if (shrink_submount(mnt)) { + shrunk = true; + if (unlikely(this_parent->mnt.mnt_flags & MNT_UMOUNT)) + return true; + } goto resume; } - return found; + return shrunk; } /* - * process a list of expirable mountpoints with the intent of discarding any - * submounts of a specific parent mountpoint + * unmount the shrinkable submounts of @mnt that aren't busy + * + * The busy check and the umount of a mount are adjacent. An umount can + * still empty or move a mount in a part of the tree that was walked + * already, so walk again until nothing goes. * * mount_lock must be held for write */ static void shrink_submounts(struct mount *mnt) { - LIST_HEAD(graveyard); - struct mount *m; - - /* extract submounts of 'mountpoint' from the expiration list */ - while (select_submounts(mnt, &graveyard)) { - while (!list_empty(&graveyard)) { - m = list_first_entry(&graveyard, struct mount, - mnt_expire); - touch_mnt_namespace(m->mnt_ns); - umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); - } + for (;;) { + if (!__shrink_submounts(mnt)) + break; } } @@ -4220,6 +4282,8 @@ static void free_mnt_ns(struct mnt_namespace *ns) if (!is_anon_ns(ns)) ns_common_free(ns); dec_mnt_namespaces(ns->ucounts); + /* the last active reference is gone, no mark can show up anymore */ + fsnotify_mntns_delete(ns); mnt_ns_tree_remove(ns); } @@ -4721,14 +4785,15 @@ int path_pivot_root(struct path *new, struct path *old) new_mnt = real_mount(new->mnt); root_mnt = real_mount(root.mnt); + /* only a mounted mount has a parent that namespace_sem pins */ + if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) + return -EINVAL; ex_parent = new_mnt->mnt_parent; root_parent = root_mnt->mnt_parent; if (IS_MNT_SHARED(old_mnt) || IS_MNT_SHARED(ex_parent) || IS_MNT_SHARED(root_parent)) return -EINVAL; - if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) - return -EINVAL; if (new_mnt->mnt.mnt_flags & MNT_LOCKED) return -EINVAL; if (d_unlinked(new->dentry)) diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 5a67648721c7..dc2447f5f092 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -100,6 +100,7 @@ void exit_cred_namespaces(struct task_struct *tsk); void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); int exec_task_namespaces(void); void deactivate_nsproxy(struct nsproxy *ns); +void nsproxy_free(struct nsproxy *ns); int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, struct cred *, struct fs_struct *); int __init nsproxy_cache_init(void); diff --git a/kernel/fork.c b/kernel/fork.c index da48168c504f..d442cd68a37a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -3338,8 +3338,9 @@ int ksys_unshare(unsigned long unshare_flags) perf_event_namespaces(current); bad_unshare_cleanup_nsproxy: + /* never installed, so no active references to drop */ if (new_nsproxy) - put_nsproxy(new_nsproxy); + nsproxy_free(new_nsproxy); bad_unshare_cleanup_cred: if (new_cred) put_cred(new_cred); diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index d9d3d5973bf5..3fb1595a4a59 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -61,7 +61,7 @@ static inline struct nsproxy *create_nsproxy(void) return nsproxy; } -static inline void nsproxy_free(struct nsproxy *ns) +void nsproxy_free(struct nsproxy *ns) { put_mnt_ns(ns->mnt_ns); put_uts_ns(ns->uts_ns); diff --git a/tools/testing/selftests/filesystems/empty_mntns/.gitignore b/tools/testing/selftests/filesystems/empty_mntns/.gitignore index 99f89d329db2..32125b3eaa80 100644 --- a/tools/testing/selftests/filesystems/empty_mntns/.gitignore +++ b/tools/testing/selftests/filesystems/empty_mntns/.gitignore @@ -2,3 +2,4 @@ clone3_empty_mntns_test empty_mntns_test overmount_chroot_test +internal_sb_reconfigure_test diff --git a/tools/testing/selftests/filesystems/empty_mntns/Makefile b/tools/testing/selftests/filesystems/empty_mntns/Makefile index 22e3fb915e81..b64818b962ca 100644 --- a/tools/testing/selftests/filesystems/empty_mntns/Makefile +++ b/tools/testing/selftests/filesystems/empty_mntns/Makefile @@ -4,9 +4,11 @@ CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS += -lcap TEST_GEN_PROGS := empty_mntns_test overmount_chroot_test clone3_empty_mntns_test +TEST_GEN_PROGS += internal_sb_reconfigure_test include ../../lib.mk $(OUTPUT)/empty_mntns_test: ../utils.c $(OUTPUT)/overmount_chroot_test: ../utils.c $(OUTPUT)/clone3_empty_mntns_test: ../utils.c +$(OUTPUT)/internal_sb_reconfigure_test: ../utils.c diff --git a/tools/testing/selftests/filesystems/empty_mntns/internal_sb_reconfigure_test.c b/tools/testing/selftests/filesystems/empty_mntns/internal_sb_reconfigure_test.c new file mode 100644 index 000000000000..cb645d1e5a9a --- /dev/null +++ b/tools/testing/selftests/filesystems/empty_mntns/internal_sb_reconfigure_test.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * The root of an empty mount namespace is a nullfs mount. Its superblock is + * kernel-internal and shared by every mount namespace. It can't be + * reconfigured, neither through fspick() nor through mount(MS_REMOUNT) nor + * through umount() of the root which remounts it read-only. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../utils.h" +#include "../wrappers.h" +#include "empty_mntns.h" +#include "kselftest_harness.h" + +#ifndef __NR_fspick +#define __NR_fspick 433 +#endif + +static int sys_fspick(int dfd, const char *path, unsigned int flags) +{ + return syscall(__NR_fspick, dfd, path, flags); +} + +/* Child exit codes. */ +enum { + CHILD_OK, + CHILD_USERNS, /* could not create the user namespace */ + CHILD_UNSHARE, /* could not create the empty mount namespace */ + CHILD_FSPICK, /* fspick() of the root was not refused with EINVAL */ + CHILD_REMOUNT, /* mount(MS_REMOUNT) was not refused with EINVAL */ + CHILD_UMOUNT, /* umount() of the root succeeded */ + CHILD_STATFS, /* statfs() of the root failed */ + CHILD_RDONLY, /* the root ended up read-only */ +}; + +static int empty_mntns_child(void) +{ + struct statfs st; + + if (enter_userns()) + return CHILD_USERNS; + if (unshare(UNSHARE_EMPTY_MNTNS)) + return CHILD_UNSHARE; + + if (sys_fspick(AT_FDCWD, "/", 0) >= 0 || errno != EINVAL) + return CHILD_FSPICK; + if (!mount(NULL, "/", NULL, MS_REMOUNT | MS_RDONLY, NULL) || + errno != EINVAL) + return CHILD_REMOUNT; + if (!umount2("/", 0)) + return CHILD_UMOUNT; + if (statfs("/", &st)) + return CHILD_STATFS; + if (st.f_flags & ST_RDONLY) + return CHILD_RDONLY; + return CHILD_OK; +} + +FIXTURE(internal_sb_reconfigure) {}; + +FIXTURE_SETUP(internal_sb_reconfigure) +{ + pid_t pid; + int status; + + pid = fork(); + ASSERT_GE(pid, 0); + if (pid == 0) { + if (enter_userns()) + _exit(1); + if (unshare(UNSHARE_EMPTY_MNTNS)) + _exit(1); + _exit(0); + } + ASSERT_EQ(waitpid(pid, &status, 0), pid); + if (!WIFEXITED(status) || WEXITSTATUS(status)) + SKIP(return, "UNSHARE_EMPTY_MNTNS not supported"); +} + +FIXTURE_TEARDOWN(internal_sb_reconfigure) {} + +TEST_F(internal_sb_reconfigure, nullfs_root) +{ + pid_t pid; + int status; + + pid = fork(); + ASSERT_GE(pid, 0); + if (pid == 0) + _exit(empty_mntns_child()); + ASSERT_EQ(waitpid(pid, &status, 0), pid); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), CHILD_OK); +} + +TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/filesystems/mount_cycle/.gitignore b/tools/testing/selftests/filesystems/mount_cycle/.gitignore index 03ca95de7765..d11f5b720d5b 100644 --- a/tools/testing/selftests/filesystems/mount_cycle/.gitignore +++ b/tools/testing/selftests/filesystems/mount_cycle/.gitignore @@ -1,3 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only unmounted_tree_test overmount_reparent_test +nsfs_rbind_loop_test +overmount_ns_file_test diff --git a/tools/testing/selftests/filesystems/mount_cycle/Makefile b/tools/testing/selftests/filesystems/mount_cycle/Makefile index 88271c82d1c1..49a8402ca858 100644 --- a/tools/testing/selftests/filesystems/mount_cycle/Makefile +++ b/tools/testing/selftests/filesystems/mount_cycle/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0 TEST_GEN_PROGS := unmounted_tree_test overmount_reparent_test +TEST_GEN_PROGS += nsfs_rbind_loop_test overmount_ns_file_test CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES) diff --git a/tools/testing/selftests/filesystems/mount_cycle/nsfs_rbind_loop_test.c b/tools/testing/selftests/filesystems/mount_cycle/nsfs_rbind_loop_test.c new file mode 100644 index 000000000000..0928a584eddc --- /dev/null +++ b/tools/testing/selftests/filesystems/mount_cycle/nsfs_rbind_loop_test.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A recursive bind mount of a namespace file that lives in another mount + * namespace copies whatever is stacked on top of it there. If that includes + * the file of the caller's own mount namespace, or of an older one, the copy + * would pin the namespace it is put in forever. The bind mount has to be + * refused, a plain bind mount of the file itself still works. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../../kselftest_harness.h" + +#define DIR_LEN 64 +#define PATH_LEN 128 + +/* Child exit codes. */ +enum { + CHILD_OK, + CHILD_UNSHARE, /* could not create the newer mount namespace */ + CHILD_PIPE, /* the parent went away */ + CHILD_TMPFS, /* could not mount the tmpfs in the new namespace */ + CHILD_REC_ALLOWED, /* the recursive bind mount was not refused */ + CHILD_REC_ERRNO, /* it was refused with the wrong error */ + CHILD_PLAIN_REFUSED, /* the plain bind mount of the file was refused */ +}; + +static int write_file(const char *path, const char *s) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_WRONLY | O_CLOEXEC); + if (fd >= 0) { + n = write(fd, s, strlen(s)); + close(fd); + } + return n == (ssize_t)strlen(s) ? 0 : -1; +} + +static int create_file(const char *path) +{ + int fd = open(path, O_WRONLY | O_CREAT | O_CLOEXEC, 0644); + + if (fd < 0) + return -1; + close(fd); + return 0; +} + +/* Become root in a new user namespace with a private mount namespace. */ +static int enter_userns(void) +{ + uid_t uid = getuid(); + gid_t gid = getgid(); + char map[32]; + + if (unshare(CLONE_NEWUSER | CLONE_NEWNS)) + return -1; + if (write_file("/proc/self/setgroups", "deny") && errno != ENOENT) + return -1; + snprintf(map, sizeof(map), "0 %d 1", uid); + if (write_file("/proc/self/uid_map", map)) + return -1; + snprintf(map, sizeof(map), "0 %d 1", gid); + if (write_file("/proc/self/gid_map", map)) + return -1; + if (setgid(0) || setuid(0)) + return -1; + return mount("", "/", NULL, MS_REC | MS_PRIVATE, NULL); +} + +static int send_msg(int fd, char msg) +{ + return write(fd, &msg, 1) == 1 ? 0 : -1; +} + +static char recv_msg(int fd) +{ + char msg; + + if (read(fd, &msg, 1) != 1) + return 0; + return msg; +} + +FIXTURE(nsfs_rbind_loop) { + char dir[DIR_LEN]; + char x[PATH_LEN]; +}; + +FIXTURE_SETUP(nsfs_rbind_loop) +{ + snprintf(self->dir, sizeof(self->dir), "/tmp/nsfs_rbind_loop.XXXXXX"); + ASSERT_NE(mkdtemp(self->dir), NULL); + if (enter_userns()) { + rmdir(self->dir); + SKIP(return, "test requires user namespaces"); + } + ASSERT_EQ(mount("tmpfs", self->dir, "tmpfs", 0, NULL), 0); + snprintf(self->x, sizeof(self->x), "%s/x", self->dir); + ASSERT_EQ(create_file(self->x), 0); +} + +FIXTURE_TEARDOWN(nsfs_rbind_loop) +{ + umount2(self->dir, MNT_DETACH); + rmdir(self->dir); +} + +/* + * The child in the newer mount namespace binds the network namespace file + * mount of the parent through @fd. Recursively that would copy the mount of + * its own mount namespace file that the parent stacked on top. + */ +static int newer_ns_child(const char *dir, int fd, int to_parent, int from_parent) +{ + char src[32], y[PATH_LEN]; + + if (unshare(CLONE_NEWNS)) + return CHILD_UNSHARE; + if (send_msg(to_parent, 'r') || recv_msg(from_parent) != 'g') + return CHILD_PIPE; + + snprintf(y, sizeof(y), "%s/y", dir); + if (mount("tmpfs", y, "tmpfs", 0, NULL)) + return CHILD_TMPFS; + snprintf(src, sizeof(src), "/proc/self/fd/%d", fd); + snprintf(y, sizeof(y), "%s/y/f", dir); + if (create_file(y)) + return CHILD_TMPFS; + + if (!mount(src, y, NULL, MS_BIND | MS_REC, NULL)) + return CHILD_REC_ALLOWED; + if (errno != EINVAL) + return CHILD_REC_ERRNO; + if (mount(src, y, NULL, MS_BIND, NULL)) + return CHILD_PLAIN_REFUSED; + umount2(y, MNT_DETACH); + return CHILD_OK; +} + +TEST_F(nsfs_rbind_loop, own_ns_file_below_foreign_source) +{ + int to_child[2], to_parent[2], fd, status; + char p[PATH_LEN]; + pid_t pid; + + snprintf(p, sizeof(p), "%s/y", self->dir); + ASSERT_EQ(mkdir(p, 0755), 0); + + /* M, a mount of our network namespace file, held by a descriptor */ + ASSERT_EQ(mount("/proc/self/ns/net", self->x, NULL, MS_BIND, NULL), 0); + fd = open(self->x, O_PATH | O_CLOEXEC); + ASSERT_GE(fd, 0); + + ASSERT_EQ(pipe(to_child), 0); + ASSERT_EQ(pipe(to_parent), 0); + pid = fork(); + ASSERT_GE(pid, 0); + if (pid == 0) { + close(to_child[1]); + close(to_parent[0]); + _exit(newer_ns_child(self->dir, fd, to_parent[1], to_child[0])); + } + close(to_child[0]); + close(to_parent[1]); + ASSERT_EQ(recv_msg(to_parent[0]), 'r'); + + /* the child's mount namespace file on top of M */ + snprintf(p, sizeof(p), "/proc/%d/ns/mnt", pid); + ASSERT_EQ(mount(p, self->x, NULL, MS_BIND, NULL), 0); + + ASSERT_EQ(send_msg(to_child[1], 'g'), 0); + ASSERT_EQ(waitpid(pid, &status, 0), pid); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), CHILD_OK); + + close(fd); + ASSERT_EQ(umount2(self->x, MNT_DETACH), 0); + ASSERT_EQ(umount2(self->x, MNT_DETACH), 0); +} + +TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/filesystems/mount_cycle/overmount_ns_file_test.c b/tools/testing/selftests/filesystems/mount_cycle/overmount_ns_file_test.c new file mode 100644 index 000000000000..ea1b33fa0bf8 --- /dev/null +++ b/tools/testing/selftests/filesystems/mount_cycle/overmount_ns_file_test.c @@ -0,0 +1,190 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A mount namespace file bind-mounted on top of the mount that is moved + * onto a shared mount isn't copied to the peers and slaves. The mount that + * already sits at the destination in a slave has to end up on top of the + * propagated copy, not below the root of the mount namespace file where no + * path walk ever finds it. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../wrappers.h" +#include "../../kselftest_harness.h" + +#define DIR_LEN 64 +#define PATH_LEN 128 + +static int write_file(const char *path, const char *s) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_WRONLY | O_CLOEXEC); + if (fd >= 0) { + n = write(fd, s, strlen(s)); + close(fd); + } + return n == (ssize_t)strlen(s) ? 0 : -1; +} + +static int create_file(const char *path, const char *s) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644); + if (fd >= 0) { + n = write(fd, s, strlen(s)); + close(fd); + } + return n == (ssize_t)strlen(s) ? 0 : -1; +} + +/* the first bytes of the file at @path, "" if it can't be read */ +static const char *read_file(const char *path, char *buf, size_t len) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_RDONLY | O_CLOEXEC); + if (fd >= 0) { + n = read(fd, buf, len - 1); + close(fd); + } + buf[n > 0 ? n : 0] = '\0'; + return buf; +} + +/* Become root in a new user namespace with a private mount namespace. */ +static int enter_userns(void) +{ + uid_t uid = getuid(); + gid_t gid = getgid(); + char map[32]; + + if (unshare(CLONE_NEWUSER | CLONE_NEWNS)) + return -1; + if (write_file("/proc/self/setgroups", "deny") && errno != ENOENT) + return -1; + snprintf(map, sizeof(map), "0 %d 1", uid); + if (write_file("/proc/self/uid_map", map)) + return -1; + snprintf(map, sizeof(map), "0 %d 1", gid); + if (write_file("/proc/self/gid_map", map)) + return -1; + if (setgid(0) || setuid(0)) + return -1; + return mount("", "/", NULL, MS_REC | MS_PRIVATE, NULL); +} + +FIXTURE(overmount_ns_file) { + char dir[DIR_LEN]; + pid_t child; +}; + +FIXTURE_SETUP(overmount_ns_file) +{ + self->child = -1; + snprintf(self->dir, sizeof(self->dir), "/tmp/overmount_ns_file.XXXXXX"); + ASSERT_NE(mkdtemp(self->dir), NULL); + if (enter_userns()) { + rmdir(self->dir); + SKIP(return, "test requires user namespaces"); + } + ASSERT_EQ(mount("tmpfs", self->dir, "tmpfs", 0, NULL), 0); +} + +FIXTURE_TEARDOWN(overmount_ns_file) +{ + if (self->child > 0) { + kill(self->child, SIGKILL); + waitpid(self->child, NULL, 0); + } + umount2(self->dir, MNT_DETACH); + rmdir(self->dir); +} + +/* + * A is a shared tmpfs and B its slave with Q, a bind mount of a file, on + * B/file. S is a bind mount of a file with N, a bind mount of a newer mount + * namespace's file, on top of it. S is moved onto A/file. Its copy S' lands + * on B/file below Q, without N. B/file keeps reading Q and once Q is + * unmounted it reads S'. + */ +TEST_F(overmount_ns_file, existing_mount_stays_on_top) +{ + char a[PATH_LEN], b[PATH_LEN], s[PATH_LEN], p[PATH_LEN], buf[16]; + int fd, pfd[2]; + char c; + + snprintf(a, sizeof(a), "%s/A", self->dir); + snprintf(b, sizeof(b), "%s/B", self->dir); + snprintf(s, sizeof(s), "%s/s", self->dir); + ASSERT_EQ(mkdir(a, 0755), 0); + ASSERT_EQ(mkdir(b, 0755), 0); + ASSERT_EQ(mkdir(s, 0755), 0); + + /* A shared, B its slave, Q on B/file */ + ASSERT_EQ(mount("tmpfs", a, "tmpfs", 0, NULL), 0); + ASSERT_EQ(mount(NULL, a, NULL, MS_SHARED, NULL), 0); + snprintf(p, sizeof(p), "%s/A/file", self->dir); + ASSERT_EQ(create_file(p, "A"), 0); + ASSERT_EQ(mount(a, b, NULL, MS_BIND, NULL), 0); + ASSERT_EQ(mount(NULL, b, NULL, MS_SLAVE, NULL), 0); + snprintf(p, sizeof(p), "%s/Q", self->dir); + ASSERT_EQ(create_file(p, "Q"), 0); + snprintf(b, sizeof(b), "%s/B/file", self->dir); + ASSERT_EQ(mount(p, b, NULL, MS_BIND, NULL), 0); + + /* S on s/f, pinned by a file descriptor before N goes on top */ + ASSERT_EQ(mount("tmpfs", s, "tmpfs", 0, NULL), 0); + snprintf(p, sizeof(p), "%s/s/f", self->dir); + ASSERT_EQ(create_file(p, "f"), 0); + snprintf(s, sizeof(s), "%s/s/S", self->dir); + ASSERT_EQ(create_file(s, "S"), 0); + ASSERT_EQ(mount(s, p, NULL, MS_BIND, NULL), 0); + fd = open(p, O_PATH | O_CLOEXEC); + ASSERT_GE(fd, 0); + + /* a newer mount namespace whose file can be bound */ + ASSERT_EQ(pipe(pfd), 0); + self->child = fork(); + ASSERT_GE(self->child, 0); + if (self->child == 0) { + close(pfd[0]); + if (unshare(CLONE_NEWNS) || write(pfd[1], "r", 1) != 1) + _exit(1); + pause(); + _exit(0); + } + close(pfd[1]); + ASSERT_EQ(read(pfd[0], &c, 1), 1); + close(pfd[0]); + snprintf(s, sizeof(s), "/proc/%d/ns/mnt", self->child); + ASSERT_EQ(mount(s, p, NULL, MS_BIND, NULL), 0); + + ASSERT_STREQ(read_file(b, buf, sizeof(buf)), "Q"); + + snprintf(a, sizeof(a), "%s/A/file", self->dir); + ASSERT_EQ(sys_move_mount(fd, "", AT_FDCWD, a, MOVE_MOUNT_F_EMPTY_PATH), 0); + close(fd); + + /* Q is still on top of the copy in B and can be unmounted */ + EXPECT_STREQ(read_file(b, buf, sizeof(buf)), "Q"); + EXPECT_EQ(umount2(b, 0), 0); + EXPECT_STREQ(read_file(b, buf, sizeof(buf)), "S"); +} + +TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/filesystems/open_tree_ns/.gitignore b/tools/testing/selftests/filesystems/open_tree_ns/.gitignore index fb12b93fbcaa..76f95c0ae5ef 100644 --- a/tools/testing/selftests/filesystems/open_tree_ns/.gitignore +++ b/tools/testing/selftests/filesystems/open_tree_ns/.gitignore @@ -1 +1,2 @@ open_tree_ns_test +open_tree_ns_covered_test diff --git a/tools/testing/selftests/filesystems/open_tree_ns/Makefile b/tools/testing/selftests/filesystems/open_tree_ns/Makefile index 4976ed1d7d4a..fb2aa77b6edb 100644 --- a/tools/testing/selftests/filesystems/open_tree_ns/Makefile +++ b/tools/testing/selftests/filesystems/open_tree_ns/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 -TEST_GEN_PROGS := open_tree_ns_test +TEST_GEN_PROGS := open_tree_ns_test open_tree_ns_covered_test CFLAGS += -Wall -O0 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS := -lcap diff --git a/tools/testing/selftests/filesystems/open_tree_ns/open_tree_ns_covered_test.c b/tools/testing/selftests/filesystems/open_tree_ns/open_tree_ns_covered_test.c new file mode 100644 index 000000000000..27f5cddfb9ef --- /dev/null +++ b/tools/testing/selftests/filesystems/open_tree_ns/open_tree_ns_covered_test.c @@ -0,0 +1,195 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * open_tree(OPEN_TREE_NAMESPACE) by a caller that isn't privileged over the + * mount namespace it copies from must not reveal what the mounts below the + * copied mount cover. Without AT_RECURSIVE the copy is refused when there's + * anything mounted below the requested directory. With AT_RECURSIVE + * unbindable mounts are copied as well. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../wrappers.h" +#include "../../kselftest_harness.h" + +#ifndef OPEN_TREE_NAMESPACE +#define OPEN_TREE_NAMESPACE (1 << 1) +#endif + +#define DIR_LEN 64 +#define PATH_LEN 128 + +/* Child exit codes. */ +enum { + CHILD_OK, + CHILD_USERNS, /* could not create the child user namespace */ + CHILD_NONREC_ALLOWED, /* the non-recursive copy was not refused */ + CHILD_NONREC_ERRNO, /* it was refused with the wrong error */ + CHILD_REC_REFUSED, /* the recursive copy failed */ + CHILD_SETNS, /* could not enter the new mount namespace */ + CHILD_NO_COVER, /* the covering mount is missing in the copy */ + CHILD_REVEALED, /* the covered file is visible in the copy */ +}; + +static int write_file(const char *path, const char *s) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_WRONLY | O_CLOEXEC); + if (fd >= 0) { + n = write(fd, s, strlen(s)); + close(fd); + } + return n == (ssize_t)strlen(s) ? 0 : -1; +} + +static int create_file(const char *path, const char *s) +{ + ssize_t n = -1; + int fd; + + fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644); + if (fd >= 0) { + n = write(fd, s, strlen(s)); + close(fd); + } + return n == (ssize_t)strlen(s) ? 0 : -1; +} + +/* Become root in a new user namespace, the uid @uid is mapped to 0. */ +static int enter_userns(uid_t uid, gid_t gid) +{ + char map[32]; + + if (unshare(CLONE_NEWUSER)) + return -1; + if (write_file("/proc/self/setgroups", "deny") && errno != ENOENT) + return -1; + snprintf(map, sizeof(map), "0 %d 1", uid); + if (write_file("/proc/self/uid_map", map)) + return -1; + snprintf(map, sizeof(map), "0 %d 1", gid); + if (write_file("/proc/self/gid_map", map)) + return -1; + return setgid(0) || setuid(0) ? -1 : 0; +} + +FIXTURE(open_tree_ns_covered) { + char dir[DIR_LEN]; + char cover[PATH_LEN]; +}; + +FIXTURE_VARIANT(open_tree_ns_covered) { + int propagation; +}; + +FIXTURE_VARIANT_ADD(open_tree_ns_covered, private_cover) { + .propagation = MS_PRIVATE, +}; + +FIXTURE_VARIANT_ADD(open_tree_ns_covered, unbindable_cover) { + .propagation = MS_UNBINDABLE, +}; + +/* + * Root in a user namespace owns a private mount namespace with a tmpfs + * on @dir and a second tmpfs covering @dir/covered/under.txt. + */ +FIXTURE_SETUP(open_tree_ns_covered) +{ + char p[PATH_LEN]; + int fd; + + snprintf(self->dir, sizeof(self->dir), "/tmp/open_tree_ns_covered.XXXXXX"); + ASSERT_NE(mkdtemp(self->dir), NULL); + if (enter_userns(getuid(), getgid()) || unshare(CLONE_NEWNS)) { + rmdir(self->dir); + SKIP(return, "test requires user namespaces"); + } + ASSERT_EQ(mount("", "/", NULL, MS_REC | MS_PRIVATE, NULL), 0); + ASSERT_EQ(mount("tmpfs", self->dir, "tmpfs", 0, NULL), 0); + + /* the flag has to exist before its rules can be checked */ + fd = sys_open_tree(AT_FDCWD, self->dir, + OPEN_TREE_NAMESPACE | OPEN_TREE_CLOEXEC); + if (fd < 0 && (errno == EINVAL || errno == ENOSYS)) { + umount2(self->dir, MNT_DETACH); + rmdir(self->dir); + SKIP(return, "OPEN_TREE_NAMESPACE not supported"); + } + ASSERT_GE(fd, 0); + close(fd); + + snprintf(self->cover, sizeof(self->cover), "%s/covered", self->dir); + ASSERT_EQ(mkdir(self->cover, 0755), 0); + snprintf(p, sizeof(p), "%s/covered/under.txt", self->dir); + ASSERT_EQ(create_file(p, "hidden"), 0); + ASSERT_EQ(mount("tmpfs", self->cover, "tmpfs", 0, NULL), 0); + ASSERT_EQ(mount(NULL, self->cover, NULL, variant->propagation, NULL), 0); +} + +FIXTURE_TEARDOWN(open_tree_ns_covered) +{ + umount2(self->dir, MNT_DETACH); + rmdir(self->dir); +} + +/* A caller in a new user namespace that doesn't own the mount namespace. */ +static int foreign_child(const char *dir) +{ + struct stat st; + int fd; + + if (enter_userns(0, 0)) + return CHILD_USERNS; + + fd = sys_open_tree(AT_FDCWD, dir, OPEN_TREE_NAMESPACE | OPEN_TREE_CLOEXEC); + if (fd >= 0) + return CHILD_NONREC_ALLOWED; + if (errno != EINVAL) + return CHILD_NONREC_ERRNO; + + fd = sys_open_tree(AT_FDCWD, dir, + OPEN_TREE_NAMESPACE | OPEN_TREE_CLOEXEC | AT_RECURSIVE); + if (fd < 0) + return CHILD_REC_REFUSED; + if (setns(fd, CLONE_NEWNS)) + return CHILD_SETNS; + if (stat("/covered", &st)) + return CHILD_NO_COVER; + if (!access("/covered/under.txt", F_OK) || errno != ENOENT) + return CHILD_REVEALED; + return CHILD_OK; +} + +TEST_F(open_tree_ns_covered, foreign_user_namespace) +{ + int status, fd; + pid_t pid; + + pid = fork(); + ASSERT_GE(pid, 0); + if (pid == 0) + _exit(foreign_child(self->dir)); + ASSERT_EQ(waitpid(pid, &status, 0), pid); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), CHILD_OK); + + /* the owner of the mount namespace keeps bind mount semantics */ + fd = sys_open_tree(AT_FDCWD, self->dir, + OPEN_TREE_NAMESPACE | OPEN_TREE_CLOEXEC); + ASSERT_GE(fd, 0); + close(fd); +} + +TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/filesystems/umount_propagation/Makefile b/tools/testing/selftests/filesystems/umount_propagation/Makefile index fc0a0783018b..eb85612abf8d 100644 --- a/tools/testing/selftests/filesystems/umount_propagation/Makefile +++ b/tools/testing/selftests/filesystems/umount_propagation/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 -TEST_GEN_PROGS := umount_propagation_test +TEST_GEN_PROGS := umount_propagation_test shrink_submounts_test CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES) diff --git a/tools/testing/selftests/filesystems/umount_propagation/shrink_submounts_test.c b/tools/testing/selftests/filesystems/umount_propagation/shrink_submounts_test.c new file mode 100644 index 000000000000..b024ae3417ce --- /dev/null +++ b/tools/testing/selftests/filesystems/umount_propagation/shrink_submounts_test.c @@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A synchronous umount first unmounts the shrinkable submounts of the + * victim that aren't busy. Every one of them has to be checked right + * before it is unmounted: unmounting one can slide a busy mount to where + * the propagated copy of the next one is looked up. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../../kselftest_harness.h" + +#ifndef FAN_REPORT_MNT +#define FAN_REPORT_MNT 0x00004000 +#endif +#ifndef FAN_MARK_MNTNS +#define FAN_MARK_MNTNS 0x00000110 +#endif +#ifndef FAN_MNT_ATTACH +#define FAN_MNT_ATTACH 0x01000000 +#endif +#ifndef FAN_MNT_DETACH +#define FAN_MNT_DETACH 0x02000000 +#endif + +#define DIR_LEN 64 +#define PATH_LEN 128 + +FIXTURE(shrink_submounts) { + char base[DIR_LEN]; + char automount[PATH_LEN]; + bool mounted; + int fan; +}; + +/* + * Shrinkable mounts come from an automount. The tracefs mount below debugfs + * is one and bind mounts inherit the flag. + */ +FIXTURE_SETUP(shrink_submounts) +{ + struct stat st; + char p[PATH_LEN]; + + self->mounted = false; + self->fan = -1; + + if (geteuid() != 0) + SKIP(return, "test requires CAP_SYS_ADMIN"); + + ASSERT_EQ(unshare(CLONE_NEWNS), 0); + ASSERT_EQ(mount("", "/", NULL, MS_REC | MS_PRIVATE, NULL), 0); + + snprintf(self->base, sizeof(self->base), "/tmp/shrink_submounts.XXXXXX"); + ASSERT_NE(mkdtemp(self->base), NULL); + ASSERT_EQ(mount("tmpfs", self->base, "tmpfs", 0, NULL), 0); + self->mounted = true; + ASSERT_EQ(mount(NULL, self->base, NULL, MS_PRIVATE, NULL), 0); + + snprintf(p, sizeof(p), "%s/dbg", self->base); + ASSERT_EQ(mkdir(p, 0755), 0); + if (mount("debugfs", p, "debugfs", 0, NULL)) { + umount2(self->base, MNT_DETACH); + rmdir(self->base); + SKIP(return, "test requires debugfs"); + } + snprintf(self->automount, sizeof(self->automount), "%s/dbg/tracing", + self->base); + snprintf(p, sizeof(p), "%s/dbg/tracing/.", self->base); + if (stat(p, &st)) { + umount2(self->base, MNT_DETACH); + rmdir(self->base); + SKIP(return, "test requires the tracefs automount"); + } +} + +FIXTURE_TEARDOWN(shrink_submounts) +{ + if (self->fan >= 0) + close(self->fan); + chdir("/"); + if (self->mounted) + umount2(self->base, MNT_DETACH); + rmdir(self->base); +} + +static bool mounted_tmpfs(const char *path) +{ + struct statfs st; + + return !statfs(path, &st) && st.f_type == TMPFS_MAGIC; +} + +/* + * P is a shared bind mount of the automount, P1 a slave of P that is shared + * in turn and P2 its peer. B, another bind mount of the automount, goes on + * P/options and propagates copies Bc1 and Bc2 onto P1/options and + * P2/options. R, a tmpfs and our working directory, sits on top of Bc2 which + * is made private first. P, with B on it, is moved to P1/instances. + * + * A synchronous umount of P1 unmounts the shrinkable submounts Bc1 and B + * first. Unmounting Bc1 takes Bc2 along and slides R to P2/options where + * the propagated copy of B is looked up next. R is busy, so B has to stay + * and the umount fails with EBUSY. + */ +TEST_F(shrink_submounts, busy_mount_moved_into_reach) +{ + char p[PATH_LEN], p1[PATH_LEN], p2[PATH_LEN], r[PATH_LEN], cwd[PATH_LEN]; + int nsfd; + + snprintf(p, sizeof(p), "%s/p", self->base); + snprintf(p1, sizeof(p1), "%s/p1", self->base); + snprintf(p2, sizeof(p2), "%s/p2", self->base); + ASSERT_EQ(mkdir(p, 0755), 0); + ASSERT_EQ(mkdir(p1, 0755), 0); + ASSERT_EQ(mkdir(p2, 0755), 0); + + /* watch the mount namespace so that the detached mounts get queued */ + self->fan = fanotify_init(FAN_REPORT_MNT, O_RDONLY); + if (self->fan >= 0) { + nsfd = open("/proc/self/ns/mnt", O_RDONLY | O_CLOEXEC); + ASSERT_GE(nsfd, 0); + EXPECT_EQ(fanotify_mark(self->fan, FAN_MARK_ADD | FAN_MARK_MNTNS, + FAN_MNT_ATTACH | FAN_MNT_DETACH, nsfd, NULL), 0); + close(nsfd); + } + + ASSERT_EQ(mount(self->automount, p, NULL, MS_BIND, NULL), 0); + ASSERT_EQ(mount(NULL, p, NULL, MS_SHARED, NULL), 0); + ASSERT_EQ(mount(p, p1, NULL, MS_BIND, NULL), 0); + ASSERT_EQ(mount(NULL, p1, NULL, MS_SLAVE, NULL), 0); + ASSERT_EQ(mount(NULL, p1, NULL, MS_SHARED, NULL), 0); + ASSERT_EQ(mount(p1, p2, NULL, MS_BIND, NULL), 0); + + /* B on P/options, copies on P1/options and P2/options */ + snprintf(r, sizeof(r), "%s/p/options", self->base); + ASSERT_EQ(mount(self->automount, r, NULL, MS_BIND, NULL), 0); + + /* R on top of Bc2 */ + snprintf(r, sizeof(r), "%s/p2/options", self->base); + ASSERT_EQ(mount(NULL, r, NULL, MS_PRIVATE, NULL), 0); + ASSERT_EQ(mount("R", r, "tmpfs", 0, NULL), 0); + ASSERT_EQ(chdir(r), 0); + + /* P, with B on it, below the victim */ + snprintf(cwd, sizeof(cwd), "%s/p1/instances", self->base); + ASSERT_EQ(mount(p, cwd, NULL, MS_MOVE, NULL), 0); + + ASSERT_TRUE(mounted_tmpfs(r)); + ASSERT_EQ(umount2(p1, 0), -1); + EXPECT_EQ(errno, EBUSY); + + /* R is still mounted and still our working directory */ + EXPECT_TRUE(mounted_tmpfs(r)); + ASSERT_NE(getcwd(cwd, sizeof(cwd)), NULL); + EXPECT_STREQ(cwd, r); +} + +/* + * T is shared and Q, a slave of T, has T moved into it, so Q receives + * propagation from its own child. M, another bind mount of the automount, is + * on T/options and that is the dentry T sits on in Q. Unmounting M makes T + * the propagated victim at that dentry in Q and takes T along. The shrink + * walk of V has just unmounted M and continues in the children of T. + */ +TEST_F(shrink_submounts, parent_goes_with_child) +{ + char v[PATH_LEN], t[PATH_LEN], q[PATH_LEN], p[PATH_LEN]; + struct stat before, after; + + snprintf(v, sizeof(v), "%s/v", self->base); + snprintf(t, sizeof(t), "%s/v/t", self->base); + snprintf(q, sizeof(q), "%s/v/q", self->base); + ASSERT_EQ(mkdir(v, 0755), 0); + ASSERT_EQ(mount("V", v, "tmpfs", 0, NULL), 0); + ASSERT_EQ(mount(NULL, v, NULL, MS_PRIVATE, NULL), 0); + ASSERT_EQ(stat(v, &before), 0); + ASSERT_EQ(mkdir(t, 0755), 0); + ASSERT_EQ(mkdir(q, 0755), 0); + + /* T shared, M on T/options before anything receives from T */ + ASSERT_EQ(mount(self->automount, t, NULL, MS_BIND, NULL), 0); + ASSERT_EQ(mount(NULL, t, NULL, MS_SHARED, NULL), 0); + snprintf(p, sizeof(p), "%s/v/t/options", self->base); + ASSERT_EQ(mount(self->automount, p, NULL, MS_BIND, NULL), 0); + + /* Q, a slave of T, and T moved into Q at the dentry M sits on */ + ASSERT_EQ(mount(t, q, NULL, MS_BIND, NULL), 0); + ASSERT_EQ(mount(NULL, q, NULL, MS_SLAVE, NULL), 0); + snprintf(p, sizeof(p), "%s/v/q/options", self->base); + ASSERT_EQ(mount(t, p, NULL, MS_MOVE, NULL), 0); + + /* M, T and then Q go, V is empty and can be unmounted */ + ASSERT_EQ(umount2(v, 0), 0); + ASSERT_EQ(stat(v, &after), 0); + EXPECT_NE(before.st_dev, after.st_dev); +} + +TEST_HARNESS_MAIN