feat: checksum pinning

Author: pd93

errors/errors.go

@@ -26,6 +26,7 @@ const (
 	CodeTaskfileNetworkTimeout
 	CodeTaskfileInvalid
 	CodeTaskfileCycle
+	CodeTaskfileDoesNotMatchChecksum
 )
 
 // Task related exit codes

errors/errors_taskfile.go

@@ -187,3 +187,24 @@ func (err TaskfileCycleError) Error() string {
 func (err TaskfileCycleError) Code() int {
 	return CodeTaskfileCycle
 }
+
+// TaskfileDoesNotMatchChecksum is returned when a Taskfile's checksum does not
+// match the one pinned in the parent Taskfile.
+type TaskfileDoesNotMatchChecksum struct {
+	URI              string
+	ExpectedChecksum string
+	ActualChecksum   string
+}
+
+func (err *TaskfileDoesNotMatchChecksum) Error() string {
+	return fmt.Sprintf(
+		"task: The checksum of the Taskfile at %q does not match!\ngot: %q\nwant: %q",
+		err.URI,
+		err.ActualChecksum,
+		err.ExpectedChecksum,
+	)
+}
+
+func (err *TaskfileDoesNotMatchChecksum) Code() int {
+	return CodeTaskfileDoesNotMatchChecksum
+}

executor_test.go

@@ -958,3 +958,22 @@ func TestFuzzyModel(t *testing.T) {
 		WithTask("install"),
 	)
 }
+
+func TestIncludeChecksum(t *testing.T) {
+	t.Parallel()
+
+	NewExecutorTest(t,
+		WithName("correct"),
+		WithExecutorOptions(
+			task.WithDir("testdata/includes_checksum/correct"),
+		),
+	)
+
+	NewExecutorTest(t,
+		WithName("incorrect"),
+		WithExecutorOptions(
+			task.WithDir("testdata/includes_checksum/incorrect"),
+		),
+		WithSetupError(),
+	)
+}

taskfile/ast/include.go

@@ -24,6 +24,7 @@ type (
 		AdvancedImport bool
 		Vars           *Vars
 		Flatten        bool
+		Checksum       string
 	}
 	// Includes is an ordered map of namespaces to includes.
 	Includes struct {
@@ -165,6 +166,7 @@ func (include *Include) UnmarshalYAML(node *yaml.Node) error {
 			Aliases  []string
 			Excludes []string
 			Vars     *Vars
+			Checksum string
 		}
 		if err := node.Decode(&includedTaskfile); err != nil {
 			return errors.NewTaskfileDecodeError(err, node)
@@ -178,6 +180,7 @@ func (include *Include) UnmarshalYAML(node *yaml.Node) error {
 		include.AdvancedImport = true
 		include.Vars = includedTaskfile.Vars
 		include.Flatten = includedTaskfile.Flatten
+		include.Checksum = includedTaskfile.Checksum
 		return nil
 	}
 
@@ -200,5 +203,7 @@ func (include *Include) DeepCopy() *Include {
 		AdvancedImport: include.AdvancedImport,
 		Vars:           include.Vars.DeepCopy(),
 		Flatten:        include.Flatten,
+		Aliases:        deepcopy.Slice(include.Aliases),
+		Checksum:       include.Checksum,
 	}
 }

taskfile/node.go

@@ -17,6 +17,8 @@ type Node interface {
 	Parent() Node
 	Location() string
 	Dir() string
+	Checksum() string
+	Verify(checksum string) bool
 	ResolveEntrypoint(entrypoint string) (string, error)
 	ResolveDir(dir string) (string, error)
 }

taskfile/node_base.go

@@ -7,8 +7,9 @@ type (
 	// designed to be embedded in other node types so that this boilerplate code
 	// does not need to be repeated.
 	BaseNode struct {
-		parent Node
-		dir    string
+		parent   Node
+		dir      string
+		checksum string
 	}
 )
 
@@ -32,10 +33,24 @@ func WithParent(parent Node) NodeOption {
 	}
 }
 
+func WithChecksum(checksum string) NodeOption {
+	return func(node *BaseNode) {
+		node.checksum = checksum
+	}
+}
+
 func (node *BaseNode) Parent() Node {
 	return node.parent
 }
 
 func (node *BaseNode) Dir() string {
 	return node.dir
 }
+
+func (node *BaseNode) Checksum() string {
+	return node.checksum
+}
+
+func (node *BaseNode) Verify(checksum string) bool {
+	return node.checksum == "" || node.checksum == checksum
+}

taskfile/reader.go

@@ -250,6 +250,7 @@ func (r *Reader) include(ctx context.Context, node Node) error {
 				AdvancedImport: include.AdvancedImport,
 				Excludes:       include.Excludes,
 				Vars:           include.Vars,
+				Checksum:       include.Checksum,
 			}
 			if err := cache.Err(); err != nil {
 				return err
@@ -267,6 +268,7 @@ func (r *Reader) include(ctx context.Context, node Node) error {
 
 			includeNode, err := NewNode(entrypoint, include.Dir, r.insecure,
 				WithParent(node),
+				WithChecksum(include.Checksum),
 			)
 			if err != nil {
 				if include.Optional {
@@ -362,7 +364,24 @@ func (r *Reader) readNodeContent(ctx context.Context, node Node) ([]byte, error)
 	if node, isRemote := node.(RemoteNode); isRemote {
 		return r.readRemoteNodeContent(ctx, node)
 	}
-	return node.Read()
+
+	// Read the Taskfile
+	b, err := node.Read()
+	if err != nil {
+		return nil, err
+	}
+
+	// If the given checksum doesn't match the sum pinned in the Taskfile
+	checksum := checksum(b)
+	if !node.Verify(checksum) {
+		return nil, &errors.TaskfileDoesNotMatchChecksum{
+			URI:              node.Location(),
+			ExpectedChecksum: node.Checksum(),
+			ActualChecksum:   checksum,
+		}
+	}
+
+	return b, nil
 }
 
 func (r *Reader) readRemoteNodeContent(ctx context.Context, node RemoteNode) ([]byte, error) {
@@ -427,17 +446,29 @@ func (r *Reader) readRemoteNodeContent(ctx context.Context, node RemoteNode) ([]
 	}
 
 	r.debugf("found remote file at %q\n", node.Location())
+
+	// If the given checksum doesn't match the sum pinned in the Taskfile
 	checksum := checksum(downloadedBytes)
-	prompt := cache.ChecksumPrompt(checksum)
-
-	// Prompt the user if required
-	if prompt != "" {
-		if err := func() error {
-			r.promptMutex.Lock()
-			defer r.promptMutex.Unlock()
-			return r.promptf(prompt, node.Location())
-		}(); err != nil {
-			return nil, &errors.TaskfileNotTrustedError{URI: node.Location()}
+	if !node.Verify(checksum) {
+		return nil, &errors.TaskfileDoesNotMatchChecksum{
+			URI:              node.Location(),
+			ExpectedChecksum: node.Checksum(),
+			ActualChecksum:   checksum,
+		}
+	}
+
+	// If there is no manual checksum pin, run the automatic checks
+	if node.Checksum() == "" {
+		// Prompt the user if required
+		prompt := cache.ChecksumPrompt(checksum)
+		if prompt != "" {
+			if err := func() error {
+				r.promptMutex.Lock()
+				defer r.promptMutex.Unlock()
+				return r.promptf(prompt, node.Location())
+			}(); err != nil {
+				return nil, &errors.TaskfileNotTrustedError{URI: node.Location()}
+			}
 		}
 	}
 

testdata/includes_checksum/correct/Taskfile.yml

@@ -0,0 +1,12 @@
+version: '3'
+
+includes:
+  included:
+    taskfile: ../included.yml
+    internal: true
+    checksum: c97f39eb96fe3fa5fe2a610d244b8449897b06f0c93821484af02e0999781bf5
+
+tasks:
+  default:
+    cmds:
+      - task: included:default

testdata/includes_checksum/correct/testdata/TestIncludeChecksum-correct.golden

@@ -0,0 +1,2 @@
+task: [included:default] echo "Hello, World!"
+Hello, World!

testdata/includes_checksum/correct_remote/Taskfile.yml

@@ -0,0 +1,12 @@
+version: '3'
+
+includes:
+  included:
+    taskfile: https://taskfile.dev
+    internal: true
+    checksum: c153e97e0b3a998a7ed2e61064c6ddaddd0de0c525feefd6bba8569827d8efe9
+
+tasks:
+  default:
+    cmds:
+      - task: included:default

testdata/includes_checksum/included.yml

@@ -0,0 +1,6 @@
+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - echo "Hello, World!"

testdata/includes_checksum/incorrect/Taskfile.yml

@@ -0,0 +1,12 @@
+version: '3'
+
+includes:
+  included:
+    taskfile: ../included.yml
+    internal: true
+    checksum: foo
+
+tasks:
+  default:
+    cmds:
+      - task: included:default

testdata/includes_checksum/incorrect/testdata/TestIncludeChecksum-incorrect-err-setup.golden

@@ -0,0 +1,3 @@
+task: The checksum of the Taskfile at "/home/pete/dev/github.com/go-task/task/testdata/includes_checksum/included.yml" does not match!
+got: "c97f39eb96fe3fa5fe2a610d244b8449897b06f0c93821484af02e0999781bf5"
+want: "foo"

testdata/includes_checksum/incorrect/testdata/TestIncludeChecksum-incorrect.golden

@@ -182,9 +182,11 @@ includes:
 
 ## Security
 
+### Automatic checksums
+
 Running commands from sources that you do not control is always a potential
-security risk. For this reason, we have added some checks when using remote
-Taskfiles:
+security risk. For this reason, we have added some automatic checks when using
+remote Taskfiles:
 
 1. When running a task from a remote Taskfile for the first time, Task will
    print a warning to the console asking you to check that you are sure that you
@@ -209,6 +211,38 @@ flag. Before enabling this flag, you should:
    containing a commit hash) to prevent Task from automatically accepting a
    prompt that says a remote Taskfile has changed.
 
+### Manual checksum pinning
+
+Alternatively, if you expect the contents of your remote files to be a constant
+value, you can pin the checksum of the included file instead:
+
+```yaml
+version: '3'
+
+includes:
+  included:
+    taskfile: https://taskfile.dev
+    checksum: c153e97e0b3a998a7ed2e61064c6ddaddd0de0c525feefd6bba8569827d8efe9
+```
+
+This will disable the automatic checksum prompts discussed above. However, if
+the checksums do not match, Task will exit immediately with an error. When
+setting this up for the first time, you may not know the correct value of the
+checksum. There are a couple of ways you can obtain this:
+
+1. Add the include normally without the `checksum` key. The first time you run
+   the included Taskfile, a `.task/remote` temporary directory is created. Find
+   the correct set of files for your included Taskfile and open the file that
+   ends with `.checksum`. You can copy the contents of this file and paste it
+   into the `checksum` key of your include. This method is safest as it allows
+   you to inspect the downloaded Taskfile before you pin it.
+2. Alternatively, add the include with a temporary random value in the
+   `checksum` key. When you try to run the Taskfile, you will get an error that
+   will report the incorrect expected checksum and the actual checksum. You can
+   copy the actual checksum and replace your temporary random value.
+
+### TLS
+
 Task currently supports both `http` and `https` URLs. However, the `http`
 requests will not execute by default unless you run the task with the
 `--insecure` flag. This is to protect you from accidentally running a remote

website/docs/experiments/remote_taskfiles.mdx

@@ -34,6 +34,7 @@ toc_max_heading_level: 5
 | `internal` | `bool`                | `false`                       | Stops any task in the included Taskfile from being callable on the command line. These commands will also be omitted from the output when used with `--list`.                                                                                            |
 | `aliases`  | `[]string`            |                               | Alternative names for the namespace of the included Taskfile.                                                                                                                                                                                            |
 | `vars`     | `map[string]Variable` |                               | A set of variables to apply to the included Taskfile.                                                                                                                                                                                                    |
+| `checksum` | `string`              |                               | The checksum of the file you expect to include. If the checksum does not match, the file will not be included.                                                                                                                                           |
 
 :::info
 

website/docs/reference/schema.mdx

@@ -684,6 +684,10 @@
                     "vars": {
                       "description": "A set of variables to apply to the included Taskfile.",
                       "$ref": "#/definitions/vars"
+                    },
+                    "checksum": {
+                      "description": "The checksum of the file you expect to include. If the checksum does not match, the file will not be included.",
+                      "type": "string"
                     }
                   }
                 }