3 files changed, 27 insertions, 10 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 8a652404eef6..e57174d43683 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -336,11 +336,11 @@ struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
  */
 static unsigned int kernfs_name_hash(const char *name, const void *ns)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(ns);
 	unsigned int len = strlen(name);
 	while (len--)
 		hash = partial_name_hash(*name++, hash);
-	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
+	hash = end_name_hash(hash);
 	hash &= 0x7fffffffU;
 	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
 	if (hash < 2)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e1574008adc9..2bcb86e6e6ca 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -840,21 +840,35 @@ repeat:
 	mutex_lock(&kernfs_mutex);
 
 	list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
+		struct kernfs_node *parent;
 		struct inode *inode;
-		struct dentry *dentry;
 
+		/*
+		 * We want fsnotify_modify() on @kn but as the
+		 * modifications aren't originating from userland don't
+		 * have the matching @file available.  Look up the inodes
+		 * and generate the events manually.
+		 */
 		inode = ilookup(info->sb, kn->ino);
 		if (!inode)
 			continue;
 
-		dentry = d_find_any_alias(inode);
-		if (dentry) {
-			fsnotify_parent(NULL, dentry, FS_MODIFY);
-			fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
-				 NULL, 0);
-			dput(dentry);
+		parent = kernfs_get_parent(kn);
+		if (parent) {
+			struct inode *p_inode;
+
+			p_inode = ilookup(info->sb, parent->ino);
+			if (p_inode) {
+				fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD,
+					 inode, FSNOTIFY_EVENT_INODE, kn->name, 0);
+				iput(p_inode);
+			}
+
+			kernfs_put(parent);
 		}
 
+		fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
+			 kn->name, 0);
 		iput(inode);
 	}
 
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 63534f5f9073..b3d73ad52b22 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -152,6 +152,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
 	struct dentry *root;
 
 	info->sb = sb;
+	/* Userspace would break if executables or devices appear on sysfs */
+	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
 	sb->s_blocksize = PAGE_SIZE;
 	sb->s_blocksize_bits = PAGE_SHIFT;
 	sb->s_magic = magic;
@@ -241,7 +243,8 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
 	info->root = root;
 	info->ns = ns;
 
-	sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info);
+	sb = sget_userns(fs_type, kernfs_test_super, kernfs_set_super, flags,
+			 &init_user_ns, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
 		kfree(info);
 	if (IS_ERR(sb))