Release 4.18 fs/notify/fanotify/fanotify.c

// SPDX-License-Identifier: GPL-2.0
#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/sched/user.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/audit.h>

#include "fanotify.h"



static bool should_merge(struct fsnotify_event *old_fsn,
			 struct fsnotify_event *new_fsn)
{
	struct fanotify_event_info *old, *new;

	pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
	old = FANOTIFY_E(old_fsn);
	new = FANOTIFY_E(new_fsn);

	if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
	    old->path.mnt == new->path.mnt &&
	    old->path.dentry == new->path.dentry)
		return true;
	return false;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Jan Kara
49
50.52%
1
25.00%
Eric Paris
42
43.30%
1
25.00%
Linus Torvalds
4
4.12%
1
25.00%
Andreas Gruenbacher
2
2.06%
1
25.00%
Total
97
100.00%
4
100.00%

/* and the list better be locked by something too! */


static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
{
	struct fsnotify_event *test_event;

	pr_debug("%s: list=%p event=%p\n", __func__, list, event);

	/*
         * Don't merge a permission event with any other event so that we know
         * the event structure we have created in fanotify_handle_event() is the
         * one we should check for permission response.
         */
	if (fanotify_is_perm_event(event->mask))
		return 0;

	list_for_each_entry_reverse(test_event, list, list) {
		if (should_merge(test_event, event)) {
			test_event->mask |= event->mask;
			return 1;
		}
	}

	return 0;
}

Contributors
Person
Tokens
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Commits
CommitProp
Eric Paris
57
71.25%
3
37.50%
Jan Kara
15
18.75%
3
37.50%
Kinglong Mee
5
6.25%
1
12.50%
Miklos Szeredi
3
3.75%
1
12.50%
Total
80
100.00%
8
100.00%



static int fanotify_get_response(struct fsnotify_group *group,
				 struct fanotify_perm_event_info *event,
				 struct fsnotify_iter_info *iter_info)
{
	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 */
	switch (event->response & ~FAN_AUDIT) {
	case FAN_ALLOW:
		ret = 0;
		break;
	case FAN_DENY:
	default:
		ret = -EPERM;
	}

	/* Check if the response should be audited */
	if (event->response & FAN_AUDIT)
		audit_fanotify(event->response & ~FAN_AUDIT);

	event->response = 0;

	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
		 group, event, ret);
	
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric Paris
87
73.73%
2
33.33%
Steve Grubb
22
18.64%
1
16.67%
Jan Kara
9
7.63%
3
50.00%
Total
118
100.00%
6
100.00%



static bool fanotify_should_send_event(struct fsnotify_iter_info *iter_info,
				       u32 event_mask, const void *data,
				       int data_type)
{
	__u32 marks_mask = 0, marks_ignored_mask = 0;
	const struct path *path = data;
	struct fsnotify_mark *mark;
	int type;

	pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",
		 __func__, iter_info->report_mask, event_mask, data, data_type);

	/* if we don't have enough info to send an event to userspace say no */
	if (data_type != FSNOTIFY_EVENT_PATH)
		return false;

	/* sorry, fanotify only gives a damn about files and dirs */
	if (!d_is_reg(path->dentry) &&
	    !d_can_lookup(path->dentry))
		return false;

	fsnotify_foreach_obj_type(type) {
		if (!fsnotify_iter_should_report_type(iter_info, type))
			continue;
		mark = iter_info->marks[type];
		/*
                 * if the event is for a child and this inode doesn't care about
                 * events on the child, don't send it!
                 */
		if (type == FSNOTIFY_OBJ_TYPE_INODE &&
		    (event_mask & FS_EVENT_ON_CHILD) &&
		    !(mark->mask & FS_EVENT_ON_CHILD))
			continue;

		marks_mask |= mark->mask;
		marks_ignored_mask |= mark->ignored_mask;
	}

	if (d_is_dir(path->dentry) &&
	    !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
		return false;

	if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
				 ~marks_ignored_mask)
		return true;

	return false;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric Paris
110
56.12%
9
47.37%
Amir Goldstein
56
28.57%
3
15.79%
Jan Kara
18
9.18%
2
10.53%
Lino Sanfilippo
5
2.55%
1
5.26%
David Howells
3
1.53%
2
10.53%
Suzuki K. Poulose
2
1.02%
1
5.26%
Al Viro
2
1.02%
1
5.26%
Total
196
100.00%
19
100.00%



struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
						 struct inode *inode, u32 mask,
						 const struct path *path)
{
	struct fanotify_event_info *event;
	gfp_t gfp = GFP_KERNEL;

	/*
         * For queues with unlimited length lost events are not expected and
         * can possibly have security implications. Avoid losing events when
         * memory is short.
         */
	if (group->max_events == UINT_MAX)
		gfp |= __GFP_NOFAIL;

	if (fanotify_is_perm_event(mask)) {
		struct fanotify_perm_event_info *pevent;

		pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
		if (!pevent)
			return NULL;
		event = &pevent->fae;
		pevent->response = 0;
		goto init;
	}
	event = kmem_cache_alloc(fanotify_event_cachep, gfp);
	if (!event)
		return NULL;
init: __maybe_unused
	fsnotify_init_event(&event->fse, inode, mask);
	event->tgid = get_pid(task_tgid(current));
	if (path) {
		event->path = *path;
		path_get(&event->path);
	} else {
		event->path.mnt = NULL;
		event->path.dentry = NULL;
	}
	return event;
}

Contributors
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CommitProp
Jan Kara
179
97.81%
2
50.00%
Miklos Szeredi
3
1.64%
1
25.00%
Al Viro
1
0.55%
1
25.00%
Total
183
100.00%
4
100.00%



static int fanotify_handle_event(struct fsnotify_group *group,
				 struct inode *inode,
				 u32 mask, const void *data, int data_type,
				 const unsigned char *file_name, u32 cookie,
				 struct fsnotify_iter_info *iter_info)
{
	int ret = 0;
	struct fanotify_event_info *event;
	struct fsnotify_event *fsn_event;

	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);
	BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);

	if (!fanotify_should_send_event(iter_info, mask, data, data_type))
		return 0;

	pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
		 mask);

	if (fanotify_is_perm_event(mask)) {
		/*
                 * fsnotify_prepare_user_wait() fails if we race with mark
                 * deletion.  Just let the operation pass in that case.
                 */
		if (!fsnotify_prepare_user_wait(iter_info))
			return 0;
	}

	event = fanotify_alloc_event(group, inode, mask, data);
	ret = -ENOMEM;
	if (unlikely(!event)) {
		/*
                 * We don't queue overflow events for permission events as
                 * there the access is denied and so no event is in fact lost.
                 */
		if (!fanotify_is_perm_event(mask))
			fsnotify_queue_overflow(group);
		goto finish;
	}

	fsn_event = &event->fse;
	ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
	if (ret) {
		/* Permission events shouldn't be merged */
		BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS);
		/* Our event wasn't used in the end. Free it. */
		fsnotify_destroy_event(group, fsn_event);

		ret = 0;
	} else if (fanotify_is_perm_event(mask)) {
		ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event),
					    iter_info);
		fsnotify_destroy_event(group, fsn_event);
	}
finish:
	if (fanotify_is_perm_event(mask))
		fsnotify_finish_user_wait(iter_info);

	return ret;
}

Contributors
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CommitProp
Jan Kara
252
79.25%
12
70.59%
Miklos Szeredi
50
15.72%
2
11.76%
Eric Paris
14
4.40%
1
5.88%
Amir Goldstein
1
0.31%
1
5.88%
Al Viro
1
0.31%
1
5.88%
Total
318
100.00%
17
100.00%



static void fanotify_free_group_priv(struct fsnotify_group *group)
{
	struct user_struct *user;

	user = group->fanotify_data.user;
	atomic_dec(&user->fanotify_listeners);
	free_uid(user);
}

Contributors
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CommitProp
Jan Kara
32
86.49%
1
50.00%
Eric Paris
5
13.51%
1
50.00%
Total
37
100.00%
2
100.00%



static void fanotify_free_event(struct fsnotify_event *fsn_event)
{
	struct fanotify_event_info *event;

	event = FANOTIFY_E(fsn_event);
	path_put(&event->path);
	put_pid(event->tgid);
	if (fanotify_is_perm_event(fsn_event->mask)) {
		kmem_cache_free(fanotify_perm_event_cachep,
				FANOTIFY_PE(fsn_event));
		return;
	}
	kmem_cache_free(fanotify_event_cachep, event);
}

Contributors
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CommitProp
Jan Kara
64
95.52%
2
66.67%
Miklos Szeredi
3
4.48%
1
33.33%
Total
67
100.00%
3
100.00%



static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
{
	kmem_cache_free(fanotify_mark_cache, fsn_mark);
}

Contributors
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CommitProp
Jan Kara
18
100.00%
1
100.00%
Total
18
100.00%
1
100.00%


const struct fsnotify_ops fanotify_fsnotify_ops = {
	.handle_event = fanotify_handle_event,
	.free_group_priv = fanotify_free_group_priv,
	.free_event = fanotify_free_event,
	.free_mark = fanotify_free_mark,
};
Overall Contributors
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CommitProp
Jan Kara
646
54.61%
15
32.61%
Eric Paris
364
30.77%
14
30.43%
Miklos Szeredi
59
4.99%
2
4.35%
Amir Goldstein
57
4.82%
3
6.52%
Steve Grubb
25
2.11%
1
2.17%
Kinglong Mee
5
0.42%
1
2.17%
Andreas Gruenbacher
5
0.42%
2
4.35%
Lino Sanfilippo
5
0.42%
1
2.17%
Linus Torvalds
4
0.34%
1
2.17%
Al Viro
4
0.34%
1
2.17%
Ingo Molnar
3
0.25%
1
2.17%
David Howells
3
0.25%
2
4.35%
Suzuki K. Poulose
2
0.17%
1
2.17%
Greg Kroah-Hartman
1
0.08%
1
2.17%
Total
1183
100.00%
46
100.00%
Directory: fs/notify/fanotify

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