1 files changed, 60 insertions, 1 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index cf176fc7086b..67c0b5e4a488 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1,13 +1,72 @@
 #include <linux/fcntl.h>
 #include <linux/fs.h>
+#include <linux/anon_inodes.h>
 #include <linux/fsnotify_backend.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
 
 #include "fanotify.h"
 
+static int fanotify_release(struct inode *ignored, struct file *file)
+{
+	struct fsnotify_group *group = file->private_data;
+
+	pr_debug("%s: file=%p group=%p\n", __func__, file, group);
+
+	/* matches the fanotify_init->fsnotify_alloc_group */
+	fsnotify_put_group(group);
+
+	return 0;
+}
+
+static const struct file_operations fanotify_fops = {
+	.poll		= NULL,
+	.read		= NULL,
+	.fasync		= NULL,
+	.release	= fanotify_release,
+	.unlocked_ioctl	= NULL,
+	.compat_ioctl	= NULL,
+};
+
+/* fanotify syscalls */
 SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags,
 		unsigned int, priority)
 {
-	return -ENOSYS;
+	struct fsnotify_group *group;
+	int f_flags, fd;
+
+	pr_debug("%s: flags=%d event_f_flags=%d priority=%d\n",
+		__func__, flags, event_f_flags, priority);
+
+	if (event_f_flags)
+		return -EINVAL;
+	if (priority)
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (flags & ~FAN_ALL_INIT_FLAGS)
+		return -EINVAL;
+
+	f_flags = (O_RDONLY | FMODE_NONOTIFY);
+	if (flags & FAN_CLOEXEC)
+		f_flags |= O_CLOEXEC;
+	if (flags & FAN_NONBLOCK)
+		f_flags |= O_NONBLOCK;
+
+	/* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
+	group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
+	if (IS_ERR(group))
+		return PTR_ERR(group);
+
+	fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
+	if (fd < 0)
+		goto out_put_group;
+
+	return fd;
+
+out_put_group:
+	fsnotify_put_group(group);
+	return fd;
 }