diff options
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 114 |
1 files changed, 88 insertions, 26 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1b9e11167bae..2b8aa15fd6df 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -590,24 +590,35 @@ static void delayed_free_vfsmnt(struct rcu_head *head) } /* call under rcu_read_lock */ -bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) +int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) { struct mount *mnt; if (read_seqretry(&mount_lock, seq)) - return false; + return 1; if (bastard == NULL) - return true; + return 0; mnt = real_mount(bastard); mnt_add_count(mnt, 1); if (likely(!read_seqretry(&mount_lock, seq))) - return true; + return 0; if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { mnt_add_count(mnt, -1); - return false; + return 1; + } + return -1; +} + +/* call under rcu_read_lock */ +bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) +{ + int res = __legitimize_mnt(bastard, seq); + if (likely(!res)) + return true; + if (unlikely(res < 0)) { + rcu_read_unlock(); + mntput(bastard); + rcu_read_lock(); } - rcu_read_unlock(); - mntput(bastard); - rcu_read_lock(); return false; } @@ -1215,7 +1226,7 @@ EXPORT_SYMBOL(replace_mount_options); /* iterator; we want it to have access to namespace_sem, thus here... */ static void *m_start(struct seq_file *m, loff_t *pos) { - struct proc_mounts *p = proc_mounts(m); + struct proc_mounts *p = m->private; down_read(&namespace_sem); if (p->cached_event == p->ns->event) { @@ -1236,7 +1247,7 @@ static void *m_start(struct seq_file *m, loff_t *pos) static void *m_next(struct seq_file *m, void *v, loff_t *pos) { - struct proc_mounts *p = proc_mounts(m); + struct proc_mounts *p = m->private; p->cached_mount = seq_list_next(v, &p->ns->list, pos); p->cached_index = *pos; @@ -1250,7 +1261,7 @@ static void m_stop(struct seq_file *m, void *v) static int m_show(struct seq_file *m, void *v) { - struct proc_mounts *p = proc_mounts(m); + struct proc_mounts *p = m->private; struct mount *r = list_entry(v, struct mount, mnt_list); return p->show(m, &r->mnt); } @@ -1350,6 +1361,36 @@ enum umount_tree_flags { UMOUNT_PROPAGATE = 2, UMOUNT_CONNECTED = 4, }; + +static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) +{ + /* Leaving mounts connected is only valid for lazy umounts */ + if (how & UMOUNT_SYNC) + return true; + + /* A mount without a parent has nothing to be connected to */ + if (!mnt_has_parent(mnt)) + return true; + + /* Because the reference counting rules change when mounts are + * unmounted and connected, umounted mounts may not be + * connected to mounted mounts. + */ + if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) + return true; + + /* Has it been requested that the mount remain connected? */ + if (how & UMOUNT_CONNECTED) + return false; + + /* Is the mount locked such that it needs to remain connected? */ + if (IS_MNT_LOCKED(mnt)) + return false; + + /* By default disconnect the mount */ + return true; +} + /* * mount_lock must be held * namespace_sem must be held for write @@ -1387,10 +1428,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) if (how & UMOUNT_SYNC) p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; - disconnect = !(((how & UMOUNT_CONNECTED) && - mnt_has_parent(p) && - (p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) || - IS_MNT_LOCKED_AND_LAZY(p)); + disconnect = disconnect_mount(p, how); pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, disconnect ? &unmounted : NULL); @@ -1527,11 +1565,8 @@ void __detach_mounts(struct dentry *dentry) while (!hlist_empty(&mp->m_list)) { mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); if (mnt->mnt.mnt_flags & MNT_UMOUNT) { - struct mount *p, *tmp; - list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { - hlist_add_head(&p->mnt_umount.s_list, &unmounted); - umount_mnt(p); - } + hlist_add_head(&mnt->mnt_umount.s_list, &unmounted); + umount_mnt(mnt); } else umount_tree(mnt, UMOUNT_CONNECTED); } @@ -2332,6 +2367,8 @@ unlock: return err; } +static bool fs_fully_visible(struct file_system_type *fs_type, int *new_mnt_flags); + /* * create a new mount for userspace and request it to be added into the * namespace's tree @@ -2363,6 +2400,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, flags |= MS_NODEV; mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } + if (type->fs_flags & FS_USERNS_VISIBLE) { + if (!fs_fully_visible(type, &mnt_flags)) + return -EPERM; + } } mnt = vfs_kern_mount(type, flags, name, data); @@ -3164,9 +3205,10 @@ bool current_chrooted(void) return chrooted; } -bool fs_fully_visible(struct file_system_type *type) +static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) { struct mnt_namespace *ns = current->nsproxy->mnt_ns; + int new_flags = *new_mnt_flags; struct mount *mnt; bool visible = false; @@ -3185,16 +3227,36 @@ bool fs_fully_visible(struct file_system_type *type) if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) continue; - /* This mount is not fully visible if there are any child mounts - * that cover anything except for empty directories. + /* Verify the mount flags are equal to or more permissive + * than the proposed new mount. + */ + if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && + !(new_flags & MNT_READONLY)) + continue; + if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && + !(new_flags & MNT_NODEV)) + continue; + if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && + ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) + continue; + + /* This mount is not fully visible if there are any + * locked child mounts that cover anything except for + * empty directories. */ list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { struct inode *inode = child->mnt_mountpoint->d_inode; - if (!S_ISDIR(inode->i_mode)) - goto next; - if (inode->i_nlink > 2) + /* Only worry about locked mounts */ + if (!(mnt->mnt.mnt_flags & MNT_LOCKED)) + continue; + /* Is the directory permanetly empty? */ + if (!is_empty_dir_inode(inode)) goto next; } + /* Preserve the locked attributes */ + *new_mnt_flags |= mnt->mnt.mnt_flags & (MNT_LOCK_READONLY | \ + MNT_LOCK_NODEV | \ + MNT_LOCK_ATIME); visible = true; goto found; next: ; |