From 396a921b1265b5a38dd3293c67139afc5a750510 Mon Sep 17 00:00:00 2001
From: Dmitry Salakhov <to@dimasalakhov.com>
Date: Mon, 13 Sep 2021 11:11:22 +1200
Subject: [PATCH] fix(stacks): allow root based compose file paths (#5564)

---
 api/exec/compose_stack.go      | 35 +++++++++++++++++++++++++++++-----
 api/exec/compose_stack_test.go | 18 +++++++++++++++++
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/api/exec/compose_stack.go b/api/exec/compose_stack.go
index 087274fe9..c3296e37d 100644
--- a/api/exec/compose_stack.go
+++ b/api/exec/compose_stack.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"path/filepath"
 	"regexp"
 	"strings"
 
@@ -58,8 +59,8 @@ func (manager *ComposeStackManager) Up(ctx context.Context, stack *portainer.Sta
 		return errors.Wrap(err, "failed to create env file")
 	}
 
-	filePaths := append([]string{stack.EntryPoint}, stack.AdditionalFiles...)
-	return manager.deployer.Deploy(ctx, stack.ProjectPath, url, stack.Name, filePaths, envFilePath)
+	filePaths := getStackFiles(stack)
+	err = manager.deployer.Deploy(ctx, stack.ProjectPath, url, stack.Name, filePaths, envFilePath)
 	return errors.Wrap(err, "failed to deploy a stack")
 }
 
@@ -73,9 +74,9 @@ func (manager *ComposeStackManager) Down(ctx context.Context, stack *portainer.S
 		defer proxy.Close()
 	}
 
-	filePaths := append([]string{stack.EntryPoint}, stack.AdditionalFiles...)
-
-	return manager.deployer.Remove(ctx, stack.ProjectPath, url, stack.Name, filePaths)
+	filePaths := getStackFiles(stack)
+	err = manager.deployer.Remove(ctx, stack.ProjectPath, url, stack.Name, filePaths)
+	return errors.Wrap(err, "failed to remove a stack")
 }
 
 // NormalizeStackName returns a new stack name with unsupported characters replaced
@@ -116,3 +117,27 @@ func createEnvFile(stack *portainer.Stack) (string, error) {
 
 	return "stack.env", nil
 }
+
+// getStackFiles returns list of stack's confile file paths.
+// items in the list would be sanitized according to following criterias:
+// 1. no empty paths
+// 2. no "../xxx" paths that are trying to escape stack folder
+// 3. no dir paths
+// 4. root paths would be made relative
+func getStackFiles(stack *portainer.Stack) []string {
+	paths := make([]string, 0, len(stack.AdditionalFiles)+1)
+
+	for _, p := range append([]string{stack.EntryPoint}, stack.AdditionalFiles...) {
+		if strings.HasPrefix(p, "/") {
+			p = `.` + p
+		}
+
+		if p == `` || p == `.` || strings.HasPrefix(p, `..`) || strings.HasSuffix(p, string(filepath.Separator)) {
+			continue
+		}
+
+		paths = append(paths, p)
+	}
+
+	return paths
+}
diff --git a/api/exec/compose_stack_test.go b/api/exec/compose_stack_test.go
index c61285ebd..0b5dec2a3 100644
--- a/api/exec/compose_stack_test.go
+++ b/api/exec/compose_stack_test.go
@@ -64,3 +64,21 @@ func Test_createEnvFile(t *testing.T) {
 		})
 	}
 }
+
+func Test_getStackFiles(t *testing.T) {
+	stack := &portainer.Stack{
+		EntryPoint: "./file", // picks entry point
+		AdditionalFiles: []string{
+			``,                  // ignores empty string
+			`.`,                 // ignores .
+			`..`,                // ignores ..
+			`./dir/`,            // ignrores paths that end with trailing /
+			`/with-root-prefix`, // replaces "root" based paths with relative
+			`./relative`,        // keeps relative paths
+			`../escape`,         // prevents dir escape
+		},
+	}
+
+	filePaths := getStackFiles(stack)
+	assert.ElementsMatch(t, filePaths, []string{`./file`, `./with-root-prefix`, `./relative`})
+}