#include #include #include #include #include #include /* UINT_MAX */ #include #include #include #include static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) { pr_debug("%s: old=%p new=%p\n", __func__, old, new); if (old->to_tell == new->to_tell && old->data_type == new->data_type && old->tgid == new->tgid) { switch (old->data_type) { case (FSNOTIFY_EVENT_PATH): if ((old->path.mnt == new->path.mnt) && (old->path.dentry == new->path.dentry)) return true; case (FSNOTIFY_EVENT_NONE): return true; default: BUG(); }; } return false; } /* Note, if we return an event in *arg that a reference is being held... */ static int fanotify_merge(struct list_head *list, struct fsnotify_event *event, void **arg) { struct fsnotify_event_holder *test_holder; struct fsnotify_event *test_event; struct fsnotify_event *new_event; struct fsnotify_event **return_event = (struct fsnotify_event **)arg; int ret = 0; pr_debug("%s: list=%p event=%p\n", __func__, list, event); *return_event = NULL; /* and the list better be locked by something too! */ list_for_each_entry_reverse(test_holder, list, event_list) { test_event = test_holder->event; if (should_merge(test_event, event)) { fsnotify_get_event(test_event); *return_event = test_event; ret = -EEXIST; /* if they are exactly the same we are done */ if (test_event->mask == event->mask) goto out; /* * if the refcnt == 1 this is the only queue * for this event and so we can update the mask * in place. */ if (atomic_read(&test_event->refcnt) == 1) { test_event->mask |= event->mask; goto out; } /* can't allocate memory, merge was no possible */ new_event = fsnotify_clone_event(test_event); if (unlikely(!new_event)) { ret = 0; goto out; } /* we didn't return the test_event, so drop that ref */ fsnotify_put_event(test_event); /* the reference we return on new_event is from clone */ *return_event = new_event; /* build new event and replace it on the list */ new_event->mask = (test_event->mask | event->mask); fsnotify_replace_event(test_holder, new_event); break; } } out: return ret; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS static int fanotify_get_response_from_access(struct fsnotify_group *group, struct fsnotify_event *event) { int ret; pr_debug("%s: group=%p event=%p\n", __func__, group, event); wait_event(group->fanotify_data.access_waitq, event->response); /* userspace responded, convert to something usable */ spin_lock(&event->lock); switch (event->response) { case FAN_ALLOW: ret = 0; break; case FAN_DENY: default: ret = -EPERM; } event->response = 0; spin_unlock(&event->lock); pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, group, event, ret); return ret; } #endif static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) { int ret; struct fsnotify_event *notify_event = NULL; BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); BUILD_BUG_ON(FAN_OPEN != FS_OPEN); BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); pr_debug("%s: group=%p event=%p\n", __func__, group, event); ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge, (void **)¬ify_event); /* -EEXIST means this event was merged with another, not that it was an error */ if (ret == -EEXIST) ret = 0; if (ret) goto out; #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS if (event->mask & FAN_ALL_PERM_EVENTS) { /* if we merged we need to wait on the new event */ if (notify_event) event = notify_event; ret = fanotify_get_response_from_access(group, event); } #endif out: if (notify_event) fsnotify_put_event(notify_event); return ret; } static bool should_send_vfsmount_event(struct fsnotify_group *group, struct vfsmount *mnt, struct inode *inode, __u32 mask) { struct fsnotify_mark *mnt_mark; struct fsnotify_mark *inode_mark; pr_debug("%s: group=%p vfsmount=%p mask=%x\n", __func__, group, mnt, mask); mnt_mark = fsnotify_find_vfsmount_mark(group, mnt); if (!mnt_mark) return false; mask &= mnt_mark->mask; mask &= ~mnt_mark->ignored_mask; if (mask) { inode_mark = fsnotify_find_inode_mark(group, inode); if (inode_mark) { mask &= ~inode_mark->ignored_mask; fsnotify_put_mark(inode_mark); } } /* find took a reference */ fsnotify_put_mark(mnt_mark); return mask; } static bool should_send_inode_event(struct fsnotify_group *group, struct inode *inode, __u32 mask) { struct fsnotify_mark *fsn_mark; pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, mask); fsn_mark = fsnotify_find_inode_mark(group, inode); if (!fsn_mark) return false; /* if the event is for a child and this inode doesn't care about * events on the child, don't send it! */ if ((mask & FS_EVENT_ON_CHILD) && !(fsn_mark->mask & FS_EVENT_ON_CHILD)) { mask = 0; } else { /* * We care about children, but do we care about this particular * type of event? */ mask &= ~FS_EVENT_ON_CHILD; mask &= fsn_mark->mask; mask &= ~fsn_mark->ignored_mask; } /* find took a reference */ fsnotify_put_mark(fsn_mark); return mask; } static bool fanotify_should_send_event(struct fsnotify_group *group, struct inode *to_tell, struct vfsmount *mnt, __u32 mask, void *data, int data_type) { pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n", __func__, group, to_tell, mnt, mask, data, data_type); /* sorry, fanotify only gives a damn about files and dirs */ if (!S_ISREG(to_tell->i_mode) && !S_ISDIR(to_tell->i_mode)) return false; /* if we don't have enough info to send an event to userspace say no */ if (data_type != FSNOTIFY_EVENT_PATH) return false; if (mnt) return should_send_vfsmount_event(group, mnt, to_tell, mask); else return should_send_inode_event(group, to_tell, mask); } const struct fsnotify_ops fanotify_fsnotify_ops = { .handle_event = fanotify_handle_event, .should_send_event = fanotify_should_send_event, .free_group_priv = NULL, .free_event_priv = NULL, .freeing_mark = NULL, };