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ff8d6e9831
This reminded me... you have two pr_debugs in fanotify_should_send_event which output redundant information. Maybe you intended it like that so it is selectable how much log spam you want, or if not you may want to apply this patch. Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@sophos.com> Signed-off-by: Eric Paris <eparis@redhat.com>
210 lines
5.6 KiB
C
210 lines
5.6 KiB
C
#include <linux/fanotify.h>
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#include <linux/fdtable.h>
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#include <linux/fsnotify_backend.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/kernel.h> /* UINT_MAX */
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#include <linux/mount.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/wait.h>
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static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
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{
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pr_debug("%s: old=%p new=%p\n", __func__, old, new);
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if (old->to_tell == new->to_tell &&
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old->data_type == new->data_type &&
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old->tgid == new->tgid) {
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switch (old->data_type) {
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case (FSNOTIFY_EVENT_PATH):
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if ((old->path.mnt == new->path.mnt) &&
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(old->path.dentry == new->path.dentry))
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return true;
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case (FSNOTIFY_EVENT_NONE):
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return true;
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default:
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BUG();
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};
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}
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return false;
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}
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/* and the list better be locked by something too! */
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static struct fsnotify_event *fanotify_merge(struct list_head *list,
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struct fsnotify_event *event)
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{
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struct fsnotify_event_holder *test_holder;
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struct fsnotify_event *test_event = NULL;
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struct fsnotify_event *new_event;
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pr_debug("%s: list=%p event=%p\n", __func__, list, event);
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list_for_each_entry_reverse(test_holder, list, event_list) {
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if (should_merge(test_holder->event, event)) {
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test_event = test_holder->event;
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break;
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}
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}
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if (!test_event)
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return NULL;
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fsnotify_get_event(test_event);
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/* if they are exactly the same we are done */
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if (test_event->mask == event->mask)
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return test_event;
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/*
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* if the refcnt == 2 this is the only queue
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* for this event and so we can update the mask
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* in place.
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*/
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if (atomic_read(&test_event->refcnt) == 2) {
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test_event->mask |= event->mask;
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return test_event;
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}
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new_event = fsnotify_clone_event(test_event);
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/* done with test_event */
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fsnotify_put_event(test_event);
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/* couldn't allocate memory, merge was not possible */
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if (unlikely(!new_event))
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return ERR_PTR(-ENOMEM);
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/* build new event and replace it on the list */
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new_event->mask = (test_event->mask | event->mask);
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fsnotify_replace_event(test_holder, new_event);
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/* we hold a reference on new_event from clone_event */
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return new_event;
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}
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#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
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static int fanotify_get_response_from_access(struct fsnotify_group *group,
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struct fsnotify_event *event)
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{
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int ret;
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pr_debug("%s: group=%p event=%p\n", __func__, group, event);
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wait_event(group->fanotify_data.access_waitq, event->response);
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/* userspace responded, convert to something usable */
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spin_lock(&event->lock);
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switch (event->response) {
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case FAN_ALLOW:
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ret = 0;
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break;
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case FAN_DENY:
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default:
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ret = -EPERM;
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}
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event->response = 0;
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spin_unlock(&event->lock);
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pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
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group, event, ret);
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return ret;
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}
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#endif
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static int fanotify_handle_event(struct fsnotify_group *group,
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struct fsnotify_mark *inode_mark,
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struct fsnotify_mark *fanotify_mark,
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struct fsnotify_event *event)
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{
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int ret = 0;
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struct fsnotify_event *notify_event = NULL;
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BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
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BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
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BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
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BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
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BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
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BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
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BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
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BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
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BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
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pr_debug("%s: group=%p event=%p\n", __func__, group, event);
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notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
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if (IS_ERR(notify_event))
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return PTR_ERR(notify_event);
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#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
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if (event->mask & FAN_ALL_PERM_EVENTS) {
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/* if we merged we need to wait on the new event */
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if (notify_event)
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event = notify_event;
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ret = fanotify_get_response_from_access(group, event);
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}
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#endif
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if (notify_event)
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fsnotify_put_event(notify_event);
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return ret;
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}
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static bool fanotify_should_send_event(struct fsnotify_group *group,
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struct inode *to_tell,
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struct fsnotify_mark *inode_mark,
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struct fsnotify_mark *vfsmnt_mark,
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__u32 event_mask, void *data, int data_type)
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{
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__u32 marks_mask, marks_ignored_mask;
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pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p "
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"mask=%x data=%p data_type=%d\n", __func__, group, to_tell,
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inode_mark, vfsmnt_mark, event_mask, data, data_type);
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/* sorry, fanotify only gives a damn about files and dirs */
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if (!S_ISREG(to_tell->i_mode) &&
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!S_ISDIR(to_tell->i_mode))
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return false;
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/* if we don't have enough info to send an event to userspace say no */
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if (data_type != FSNOTIFY_EVENT_PATH)
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return false;
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if (inode_mark && vfsmnt_mark) {
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marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
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marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
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} else if (inode_mark) {
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/*
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* if the event is for a child and this inode doesn't care about
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* events on the child, don't send it!
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*/
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if ((event_mask & FS_EVENT_ON_CHILD) &&
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!(inode_mark->mask & FS_EVENT_ON_CHILD))
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return false;
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marks_mask = inode_mark->mask;
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marks_ignored_mask = inode_mark->ignored_mask;
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} else if (vfsmnt_mark) {
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marks_mask = vfsmnt_mark->mask;
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marks_ignored_mask = vfsmnt_mark->ignored_mask;
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} else {
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BUG();
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}
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if (event_mask & marks_mask & ~marks_ignored_mask)
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return true;
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return false;
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}
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const struct fsnotify_ops fanotify_fsnotify_ops = {
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.handle_event = fanotify_handle_event,
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.should_send_event = fanotify_should_send_event,
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.free_group_priv = NULL,
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.free_event_priv = NULL,
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.freeing_mark = NULL,
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};
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