1 files changed, 39 insertions, 6 deletions

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 1ed8473ec537..2565809fbb34 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -87,6 +87,7 @@ static struct inode *bpf_get_inode(struct super_block *sb,
 	switch (mode & S_IFMT) {
 	case S_IFDIR:
 	case S_IFREG:
+	case S_IFLNK:
 		break;
 	default:
 		return ERR_PTR(-EINVAL);
@@ -119,6 +120,16 @@ static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
 	return 0;
 }
 
+static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode,
+				struct inode *dir)
+{
+	d_instantiate(dentry, inode);
+	dget(dentry);
+
+	dir->i_mtime = current_time(dir);
+	dir->i_ctime = dir->i_mtime;
+}
+
 static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
@@ -133,9 +144,7 @@ static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	inc_nlink(inode);
 	inc_nlink(dir);
 
-	d_instantiate(dentry, inode);
-	dget(dentry);
-
+	bpf_dentry_finalize(dentry, inode, dir);
 	return 0;
 }
 
@@ -151,9 +160,7 @@ static int bpf_mkobj_ops(struct inode *dir, struct dentry *dentry,
 	inode->i_op = iops;
 	inode->i_private = dentry->d_fsdata;
 
-	d_instantiate(dentry, inode);
-	dget(dentry);
-
+	bpf_dentry_finalize(dentry, inode, dir);
 	return 0;
 }
 
@@ -181,13 +188,37 @@ bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags)
 {
 	if (strchr(dentry->d_name.name, '.'))
 		return ERR_PTR(-EPERM);
+
 	return simple_lookup(dir, dentry, flags);
 }
 
+static int bpf_symlink(struct inode *dir, struct dentry *dentry,
+		       const char *target)
+{
+	char *link = kstrdup(target, GFP_USER | __GFP_NOWARN);
+	struct inode *inode;
+
+	if (!link)
+		return -ENOMEM;
+
+	inode = bpf_get_inode(dir->i_sb, dir, S_IRWXUGO | S_IFLNK);
+	if (IS_ERR(inode)) {
+		kfree(link);
+		return PTR_ERR(inode);
+	}
+
+	inode->i_op = &simple_symlink_inode_operations;
+	inode->i_link = link;
+
+	bpf_dentry_finalize(dentry, inode, dir);
+	return 0;
+}
+
 static const struct inode_operations bpf_dir_iops = {
 	.lookup		= bpf_lookup,
 	.mknod		= bpf_mkobj,
 	.mkdir		= bpf_mkdir,
+	.symlink	= bpf_symlink,
 	.rmdir		= simple_rmdir,
 	.rename		= simple_rename,
 	.link		= simple_link,
@@ -324,6 +355,8 @@ static void bpf_evict_inode(struct inode *inode)
 	truncate_inode_pages_final(&inode->i_data);
 	clear_inode(inode);
 
+	if (S_ISLNK(inode->i_mode))
+		kfree(inode->i_link);
 	if (!bpf_inode_type(inode, &type))
 		bpf_any_put(inode->i_private, type);
 }