macOS CIS: Use find command (exposed as fleetd table) instead of relying on the osquery core file table (#12560)

#10292, #12554 When scanning tens of thousands of files for permissions, using the `find` command exposed as a fleetd table is more performant than trying to use the `file` table. This change caused the watchdog to *stop* killing osquery because of exceeding memory or CPU limit. - [X] Changes file added for user-visible changes in `changes/` or `orbit/changes/`. See [Changes files](https://fleetdm.com/docs/contributing/committing-changes#changes-files) for more information. - ~[ ] Documented any API changes (docs/Using-Fleet/REST-API.md or docs/Contributing/API-for-contributors.md)~ - ~[ ] Documented any permissions changes~ - ~[ ] Input data is properly validated, `SELECT *` is avoided, SQL injection is prevented (using placeholders for values in statements)~ - ~[ ] Added support on fleet's osquery simulator `cmd/osquery-perf` for new osquery data ingestion features.~ - [X] Added/updated tests - [X] Manual QA for all new/changed functionality - For Orbit and Fleet Desktop changes: - [X] Manual QA must be performed in the three main OSs, macOS, Windows and Linux. - ~[ ] Auto-update manual QA, from released version of component to new version (see [tools/tuf/test](../tools/tuf/test/README.md)).~
2023-06-29 16:22:41 -03:00
parent 9f3331ef94
commit 810eb58b95
8 changed files with 2522 additions and 879 deletions
@@ -9,6 +9,7 @@ import (
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/diskutil/corestorage"
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/dscl"
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/filevault_prk"
+	"github.com/fleetdm/fleet/v4/orbit/pkg/table/find_cmd"
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/firmware_eficheck_integrity_check"
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/nvram_info"
 	"github.com/fleetdm/fleet/v4/orbit/pkg/table/pmset"
@@ -46,6 +47,7 @@ func PlatformTables() []osquery.OsqueryPlugin {
 		table.NewPlugin("corestorage_logical_volumes", corestorage.LogicalVolumesColumns(), corestorage.LogicalVolumesGenerate),
 		table.NewPlugin("corestorage_logical_volume_families", corestorage.LogicalVolumeFamiliesColumns(), corestorage.LogicalVolumeFamiliesGenerate),
 		table.NewPlugin("filevault_prk", filevault_prk.Columns(), filevault_prk.Generate),
+		table.NewPlugin("find_cmd", find_cmd.Columns(), find_cmd.Generate),

 		// Macadmins extension tables
 		table.NewPlugin("filevault_users", filevaultusers.FileVaultUsersColumns(), filevaultusers.FileVaultUsersGenerate),
@@ -0,0 +1,146 @@
+//go:build darwin
+// +build darwin
+
+// Package find_cmd implements a table that executes the /usr/bin/find command.
+// This table provides only a subset of the find functionality. Currently only
+// allows setting the -perm and -type arguments.
+//
+// NOTE(lucas): Why does this table exist?
+// Initially we implemented queries that used the osquery core `file` table,
+// but when processing a high number (10k+) of files it exceeded osquery
+// default CPU and memory limits.
+package find_cmd
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/osquery/osquery-go/plugin/table"
+	"github.com/rs/zerolog/log"
+)
+
+// Columns is the schema of the table.
+func Columns() []table.ColumnDefinition {
+	return []table.ColumnDefinition{
+		// directory is the first argument of the find command (basically
+		// where to search for files).
+		table.TextColumn("directory"),
+		// type allows setting find's '-type' argument.
+		table.TextColumn("type"),
+		// perm allows setting find's '-perm' argument.
+		table.TextColumn("perm"),
+		// path are the found directories.
+		table.TextColumn("path"),
+	}
+}
+
+var permRegexp = regexp.MustCompile("[-+]*\\d+")
+
+// Generate is called to return the results for the table at query time.
+//
+// Constraints for generating can be retrieved from the queryContext.
+func Generate(ctx context.Context, queryContext table.QueryContext) ([]map[string]string, error) {
+	getArgumentOpEqual := func(argName string) string {
+		argValue := ""
+		if constraints, ok := queryContext.Constraints[argName]; ok {
+			for _, constraint := range constraints.Constraints {
+				if constraint.Operator == table.OperatorEquals {
+					argValue = constraint.Expression
+				}
+			}
+		}
+		return argValue
+	}
+
+	directory := getArgumentOpEqual("directory")
+	if directory == "" {
+		return nil, errors.New("missing directory argument")
+	}
+	if !filepath.IsAbs(directory) {
+		return nil, errors.New("directory must be an absolute path")
+	}
+
+	findType := getArgumentOpEqual("type")
+	if findType != "" {
+		switch findType {
+		case "b", "c", "d", "f", "l", "p", "s":
+			// OK
+		default:
+			return nil, errors.New("type must be one of: 'b', 'c', 'd', 'f', 'l', 'p' or 's'")
+		}
+	}
+
+	perm := getArgumentOpEqual("perm")
+	if perm != "" {
+		if !permRegexp.Match([]byte(perm)) {
+			return nil, fmt.Errorf("perm must be of the form: %s", permRegexp)
+		}
+	}
+
+	args := []string{directory}
+	if findType != "" {
+		args = append(args, "-type", findType)
+	}
+	if perm != "" {
+		args = append(args, "-perm", perm)
+	}
+
+	cmd := exec.Command("/usr/bin/find", args...)
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("create stdout pipe: %w", err)
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return nil, fmt.Errorf("create stderr pipe: %w", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		return nil, fmt.Errorf("command start failed: %w", err)
+	}
+
+	var outDirs []string
+	reader := bufio.NewReader(stdoutPipe)
+	line, err := reader.ReadString('\n')
+	for err == nil {
+		line = strings.TrimSuffix(line, "\n")
+		if line == "" {
+			continue
+		}
+		outDirs = append(outDirs, line)
+		line, err = reader.ReadString('\n')
+	}
+	if err != io.EOF {
+		return nil, fmt.Errorf("unexpected error: %w", err)
+	}
+
+	stderr, err := io.ReadAll(stderrPipe)
+	if err != nil {
+		log.Debug().Err(err).Msg("failed to read find stderr")
+	}
+
+	if err := cmd.Wait(); err != nil {
+		// We ignore error as these could be of the form:
+		// 'find: /System/Volumes/Data/Library/Caches/com.apple.aned: Operation not permitted'
+		// which are files unaccessible even for root.
+		log.Debug().Err(err).Bytes("stderr", stderr).Msg("find failed")
+	}
+
+	rows := make([]map[string]string, 0, len(outDirs))
+	for _, outDir := range outDirs {
+		rows = append(rows, map[string]string{
+			"directory": directory,
+			"perm":      perm,
+			"type":      findType,
+			"path":      outDir,
+		})
+	}
+	return rows, nil
+}
@@ -0,0 +1,188 @@
+//go:build darwin
+// +build darwin
+
+package find_cmd
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/osquery/osquery-go/plugin/table"
+	"github.com/stretchr/testify/require"
+	"golang.org/x/net/context"
+)
+
+// TestGenerate tests the find_cmd table generation.
+func TestGenerate(t *testing.T) {
+	// Test not setting required column directory.
+	_, err := Generate(context.Background(), table.QueryContext{})
+	require.Error(t, err)
+
+	testDir := t.TempDir()
+
+	// Test with an empty directory.
+	rows, err := Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+	require.Len(t, rows, 1)
+	require.Equal(t, rows[0]["path"], testDir)
+
+	// Test with invalid type argument.
+	_, err = Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+			"type": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: "z",
+					},
+				},
+			},
+		},
+	})
+	require.Error(t, err)
+
+	// Test with invalid perm argument.
+	_, err = Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+			"perm": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: "foobar",
+					},
+				},
+			},
+		},
+	})
+	require.Error(t, err)
+
+	// Populate the directory.
+	f, err := os.Create(filepath.Join(testDir, "foo.txt"))
+	require.NoError(t, err)
+	err = f.Close()
+	require.NoError(t, err)
+	err = os.Chmod(filepath.Join(testDir, "foo.txt"), os.ModePerm)
+	require.NoError(t, err)
+	require.NoError(t, err)
+	err = os.Mkdir(filepath.Join(testDir, "zoo"), os.ModePerm)
+	require.NoError(t, err)
+	err = os.Chmod(filepath.Join(testDir, "zoo"), os.ModePerm)
+	require.NoError(t, err)
+
+	// Test directory with a few entries.
+	rows, err = Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+	require.Len(t, rows, 3)
+	require.Equal(t, rows[0]["path"], testDir)
+	require.Equal(t, rows[1]["path"], filepath.Join(testDir, "zoo"))
+	require.Equal(t, rows[2]["path"], filepath.Join(testDir, "foo.txt"))
+
+	// Test directory with a few entries and setting the perm column.
+	rows, err = Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+			"perm": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: "-2",
+					},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+	require.Len(t, rows, 2)
+	require.Equal(t, rows[0]["path"], filepath.Join(testDir, "zoo"))
+	require.Equal(t, rows[1]["path"], filepath.Join(testDir, "foo.txt"))
+
+	// Test directory with a few entries and setting the perm and type column.
+	rows, err = Generate(context.Background(), table.QueryContext{
+		Constraints: map[string]table.ConstraintList{
+			"directory": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: testDir,
+					},
+				},
+			},
+			"perm": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: "-2",
+					},
+				},
+			},
+			"type": {
+				Affinity: table.ColumnTypeText,
+				Constraints: []table.Constraint{
+					{
+						Operator:   table.OperatorEquals,
+						Expression: "d",
+					},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+	require.Len(t, rows, 1)
+	require.Equal(t, rows[0]["path"], filepath.Join(testDir, "zoo"))
+}