diff options
Diffstat (limited to 'fs/notify/fanotify/fanotify.c')
| -rw-r--r-- | fs/notify/fanotify/fanotify.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c new file mode 100644 index 00000000000..85366c78cc3 --- /dev/null +++ b/fs/notify/fanotify/fanotify.c @@ -0,0 +1,209 @@ +#include <linux/fanotify.h> +#include <linux/fdtable.h> +#include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/kernel.h> /* UINT_MAX */ +#include <linux/mount.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/wait.h> + +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; +} + +/* and the list better be locked by something too! */ +static struct fsnotify_event *fanotify_merge(struct list_head *list, + struct fsnotify_event *event) +{ + struct fsnotify_event_holder *test_holder; + struct fsnotify_event *test_event = NULL; + struct fsnotify_event *new_event; + + pr_debug("%s: list=%p event=%p\n", __func__, list, event); + + + list_for_each_entry_reverse(test_holder, list, event_list) { + if (should_merge(test_holder->event, event)) { + test_event = test_holder->event; + break; + } + } + + if (!test_event) + return NULL; + + fsnotify_get_event(test_event); + + /* if they are exactly the same we are done */ + if (test_event->mask == event->mask) + return test_event; + + /* + * if the refcnt == 2 this is the only queue + * for this event and so we can update the mask + * in place. + */ + if (atomic_read(&test_event->refcnt) == 2) { + test_event->mask |= event->mask; + return test_event; + } + + new_event = fsnotify_clone_event(test_event); + + /* done with test_event */ + fsnotify_put_event(test_event); + + /* couldn't allocate memory, merge was not possible */ + if (unlikely(!new_event)) + return ERR_PTR(-ENOMEM); + + /* build new event and replace it on the list */ + new_event->mask = (test_event->mask | event->mask); + fsnotify_replace_event(test_holder, new_event); + + /* we hold a reference on new_event from clone_event */ + return new_event; +} + +#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_mark *inode_mark, + struct fsnotify_mark *fanotify_mark, + struct fsnotify_event *event) +{ + int ret = 0; + 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); + + notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge); + if (IS_ERR(notify_event)) + return PTR_ERR(notify_event); + +#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 + + if (notify_event) + fsnotify_put_event(notify_event); + + return ret; +} + +static bool fanotify_should_send_event(struct fsnotify_group *group, + struct inode *to_tell, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmnt_mark, + __u32 event_mask, void *data, int data_type) +{ + __u32 marks_mask, marks_ignored_mask; + + pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p " + "mask=%x data=%p data_type=%d\n", __func__, group, to_tell, + inode_mark, vfsmnt_mark, event_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 (inode_mark && vfsmnt_mark) { + marks_mask = (vfsmnt_mark->mask | inode_mark->mask); + marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); + } else if (inode_mark) { + /* + * if the event is for a child and this inode doesn't care about + * events on the child, don't send it! + */ + if ((event_mask & FS_EVENT_ON_CHILD) && + !(inode_mark->mask & FS_EVENT_ON_CHILD)) + return false; + marks_mask = inode_mark->mask; + marks_ignored_mask = inode_mark->ignored_mask; + } else if (vfsmnt_mark) { + marks_mask = vfsmnt_mark->mask; + marks_ignored_mask = vfsmnt_mark->ignored_mask; + } else { + BUG(); + } + + if (event_mask & marks_mask & ~marks_ignored_mask) + return true; + + return false; +} + +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, +}; |