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;
 }