fix(generate): Ensure files are created instead output directory (#3195)

* fix(generate): First pass at fixing path traversal vuln

* Add test

Author: kyleconroy

internal/cmd/generate.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime/trace"
+	"strings"
 	"sync"
 
 	"google.golang.org/grpc"
@@ -208,8 +209,21 @@ func (g *generator) ProcessResult(ctx context.Context, combo config.CombinedSett
 		files[file.Name] = string(file.Contents)
 	}
 	g.m.Lock()
+
+	// out is specified by the user, not a plugin
+	absout := filepath.Join(g.dir, out)
+
 	for n, source := range files {
 		filename := filepath.Join(g.dir, out, n)
+		// filepath.Join calls filepath.Clean which should remove all "..", but
+		// double check to make sure
+		if strings.Contains(filename, "..") {
+			return fmt.Errorf("invalid file output path: %s", filename)
+		}
+		// The output file must be contained inside the output directory
+		if !strings.HasPrefix(filename, absout) {
+			return fmt.Errorf("invalid file output path: %s", filename)
+		}
 		g.output[filename] = source
 	}
 	g.m.Unlock()

internal/endtoend/testdata/wasm_plugin_sqlc_gen_unsafe_paths/query.sql

@@ -0,0 +1,19 @@
+-- name: GetAuthor :one
+SELECT * FROM authors
+WHERE id = $1 LIMIT 1;
+
+-- name: ListAuthors :many
+SELECT * FROM authors
+ORDER BY name;
+
+-- name: CreateAuthor :one
+INSERT INTO authors (
+          name, bio
+) VALUES (
+  $1, $2
+)
+RETURNING *;
+
+-- name: DeleteAuthor :exec
+DELETE FROM authors
+WHERE id = $1;

internal/endtoend/testdata/wasm_plugin_sqlc_gen_unsafe_paths/schema.sql

@@ -0,0 +1,5 @@
+CREATE TABLE authors (
+          id   BIGSERIAL PRIMARY KEY,
+          name text      NOT NULL,
+          bio  text
+);

internal/endtoend/testdata/wasm_plugin_sqlc_gen_unsafe_paths/sqlc.json

@@ -0,0 +1,25 @@
+{
+  "version": "2",
+  "sql": [
+    {
+      "schema": "schema.sql",
+      "queries": "query.sql",
+      "engine": "postgresql",
+      "codegen": [
+        {
+          "out": "gen",
+          "plugin": "test"
+        }
+      ]
+    }
+  ],
+  "plugins": [
+    {
+      "name": "test",
+      "wasm": {
+        "url": "https://github.com/sqlc-dev/sqlc-gen-unsafe-paths/releases/download/v0.1.1/sqlc-gen-unsafe-paths.wasm",
+        "sha256": "e53ac951dd41b1e4c365e757d9735886f7c8e92f2056ce0be9a5cfcf677c45d9"
+      }
+    }
+  ]
+}

internal/endtoend/testdata/wasm_plugin_sqlc_gen_unsafe_paths/stderr.txt

@@ -0,0 +1,2 @@
+# package test
+error generating code: invalid file output path: /tmp/unsafe.txt