new(pkg/driver,cmd/driver): implemented kmod modprobe/insmod.

Signed-off-by: Federico Di Pierro <[email protected]>

cmd/driver/prepare/prepare.go

@@ -86,6 +86,7 @@ func (o *driverPrepareOptions) RunDriverPrepare(_ context.Context, _ []string) e
 	o.Printer.Logger.Info("Running falcoctl driver prepare", o.Printer.Logger.Args(
 		"driver version", o.DriverVersion,
 		"driver type", driver.Type,
+		"driver name", o.Name,
 		"arch", info.Architecture,
 		"kernel release", info.KernelRelease,
 		"kernel version", info.KernelVersion))
@@ -111,12 +112,15 @@ func (o *driverPrepareOptions) RunDriverPrepare(_ context.Context, _ []string) e
 		return err
 	}
 
+	var dest string
 	if o.Download {
 		// Fixup kernel information before attempting to download
 		downloadInfo := d.FixupKernel(info)
 
-		err = d.Download(downloadInfo, o.Driver, driver.Type, o.DriverVersion, o.DriverRepos)
+		dest, err = d.Download(downloadInfo, o.Driver, driver.Type, o.DriverVersion, o.DriverRepos)
 		if err == nil {
+			// We don't care about errors at this stage
+			_ = driver.Type.Load(o.Printer, dest, false)
 			return nil
 		}
 		// Print the error but go on
@@ -125,7 +129,20 @@ func (o *driverPrepareOptions) RunDriverPrepare(_ context.Context, _ []string) e
 	}
 
 	if o.Build {
-		err = d.Build()
+		dest, err = d.Build()
+		if err == nil {
+			// We don't care about errors
+			_ = driver.Type.Load(o.Printer, dest, false)
+		}
+	}
+
+	if err != nil {
+		o.Printer.Logger.Error(err.Error())
+		// Fallback: try to load any available driver.
+		// It is only useful for kmod, as it will try to
+		// modprobe a pre-existent version of the driver,
+		// hoping it will be compatible.
+		_ = driver.Type.Load(o.Printer, o.Name, true)
 	}
-	return err
+	return fmt.Errorf("last error: %w", err)
 }

pkg/driver/distro/distro.go

@@ -43,8 +43,8 @@ type Distro interface {
 	init(printer *output.Printer, id string, cfg *ini.File) error // private
 	GetTargetID(i driverkernel.Info) string
 	FixupKernel(i driverkernel.Info) driverkernel.Info
-	Download(i driverkernel.Info, opts *options.Driver, driverType drivertype.DriverType, driverVer string, repos []string) error
-	Build() error
+	Download(i driverkernel.Info, opts *options.Driver, driverType drivertype.DriverType, driverVer string, repos []string) (string, error)
+	Build() (string, error)
 	PreferredDriver(i driverkernel.Info) drivertype.DriverType
 }
 

pkg/driver/distro/generic.go

@@ -49,23 +49,23 @@ func (g *generic) FixupKernel(i driverkernel.Info) driverkernel.Info {
 	return i
 }
 
-func (g *generic) Build() error {
+func (g *generic) Build() (string, error) {
 	// TODO compile
 	// flatcar specific: flatcar_relocate_tools
 	// cos specific...
 	// minikube specific...
-	return fmt.Errorf("build unimplemented")
+	return "", fmt.Errorf("build unimplemented")
 }
 
-func (g *generic) Download(i driverkernel.Info, opts *options.Driver, driverType drivertype.DriverType, driverVer string, repos []string) error {
+func (g *generic) Download(i driverkernel.Info, opts *options.Driver, driverType drivertype.DriverType, driverVer string, repos []string) (string, error) {
 	// Skip if existent
 	driverFileName := g.toFilename(i, opts, driverType)
 	destination := fmt.Sprintf("%s/.falco/%s/%s/%s", homedir.Get(), driverVer, i.Architecture, driverFileName)
 	f, err := os.Open(destination) //nolint:gosec
 	if err == nil {
 		_ = f.Close()
 		g.printer.Logger.Info("Skipping download, driver already present.", g.printer.Logger.Args("path", destination))
-		return nil
+		return destination, nil
 	}
 
 	// Try to download from any specified repository,
@@ -81,16 +81,16 @@ func (g *generic) Download(i driverkernel.Info, opts *options.Driver, driverType
 
 		out, err := os.Create(destination) //nolint:gosec
 		if err != nil {
-			return err
+			return destination, err
 		}
 		_, err = io.Copy(out, resp.Body)
 		if err != nil {
-			return err
+			return destination, err
 		}
 		_ = resp.Body.Close()
-		return nil
+		return destination, nil
 	}
-	return fmt.Errorf("unable to find a prebuilt %s driver", opts.Name)
+	return destination, fmt.Errorf("unable to find a prebuilt %s driver", opts.Name)
 }
 
 func (g *generic) PreferredDriver(_ driverkernel.Info) drivertype.DriverType {

pkg/driver/type/bpf.go

@@ -41,6 +41,10 @@ func (b *bpf) Prepare(printer *output.Printer, _ string) error {
 	return mounter.Mount("debugfs", "/sys/kernel/debug", "debugfs", []string{"nodev"})
 }
 
+func (b *bpf) Load(_ *output.Printer, _ string, _ bool) error {
+	return nil
+}
+
 func (b *bpf) Extension() string {
 	return ".o"
 }

pkg/driver/type/kmod.go

@@ -62,66 +62,91 @@ func (k *kmod) Prepare(printer *output.Printer, driverName string) error {
 	}
 
 	kmodName := strings.ReplaceAll(driverName, "-", "_")
-	args := printer.Logger.Args("kmod", kmodName)
-
-	printer.Logger.Info("Check if kernel module is still loaded.", args)
+	printer.Logger.Info("Check if kernel module is still loaded.")
 	lsmodCmdArgs := fmt.Sprintf(`lsmod | cut -d' ' -f1 | grep -qx %q`, kmodName)
 	_, err = exec.Command("bash", "-c", lsmodCmdArgs).Output() //nolint:gosec
 	if err == nil {
 		unloaded := false
 		// Module is still loaded, try to remove it
 		for i := 0; i < maxRmmodWait; i++ {
-			printer.Logger.Info("Kernel module is still loaded.", args)
-			printer.Logger.Info("Trying to unload it with 'rmmod'.", args)
+			printer.Logger.Info("Kernel module is still loaded.")
+			printer.Logger.Info("Trying to unload it with 'rmmod'.")
 			if _, err = exec.Command("rmmod", kmodName).Output(); err == nil { //nolint:gosec
-				printer.Logger.Info("OK! Unloading module succeeded.", args)
+				printer.Logger.Info("OK! Unloading module succeeded.")
 				unloaded = true
 				break
 			}
-			printer.Logger.Info("Nothing to do...'falcoctl' will wait until you remove the kernel module to have a clean termination.", args)
-			printer.Logger.Info("Check that no process is using the kernel module with 'lsmod'.", args)
-			printer.Logger.Info("Sleep 5 seconds...", args)
+			printer.Logger.Info("Nothing to do...'falcoctl' will wait until you remove the kernel module to have a clean termination.")
+			printer.Logger.Info("Check that no process is using the kernel module with 'lsmod'.")
+			printer.Logger.Info("Sleep 5 seconds...")
 			time.Sleep(rmmodWaitTime)
 		}
 		if !unloaded {
-			printer.Logger.Warn("Kernel module is still loaded, you could have incompatibility issues.", args)
+			printer.Logger.Warn("Kernel module is still loaded, you could have incompatibility issues.")
 		}
 	} else {
-		printer.Logger.Info("OK! There is no module loaded.", args)
+		printer.Logger.Info("OK! There is no module loaded.")
 	}
 
 	_, err = exec.Command("bash", "-c", "hash dkms").Output()
 	if err != nil {
-		printer.Logger.Info("Skipping dkms remove (dkms not found).", args)
+		printer.Logger.Info("Skipping dkms remove (dkms not found).")
 		return nil
 	}
 
-	printer.Logger.Info("Check all versions of kernel module in dkms.", args)
+	printer.Logger.Info("Check all versions of kernel module in dkms.")
 	dkmsLsCmdArgs := fmt.Sprintf(`dkms status -m %q | tr -d "," | tr -d ":" | tr "/" " " | cut -d' ' -f2`, kmodName)
 	out, err := exec.Command("bash", "-c", dkmsLsCmdArgs).Output() //nolint:gosec
 	if err != nil {
-		printer.Logger.Warn("Listing kernel module versions failed.", args, printer.Logger.Args("reason", err))
+		printer.Logger.Warn("Listing kernel module versions failed.", printer.Logger.Args("reason", err))
 		return nil
 	}
 	if len(out) == 0 {
-		printer.Logger.Info("OK! There are no module versions in dkms.", args)
+		printer.Logger.Info("OK! There are no module versions in dkms.")
 	} else {
 		driverVersions := strings.Split(string(out), "\n")
-		printer.Logger.Info("There are some module versions in dkms.", args)
-		printer.Logger.Info("Removing all the following versions from dkms.", args, printer.Logger.Args("versions", driverVersions))
+		printer.Logger.Info("There are some module versions in dkms.")
+		printer.Logger.Info("Removing all the following versions from dkms.", printer.Logger.Args("versions", driverVersions))
 		for _, dVer := range driverVersions {
 			dkmsRmCmdArgs := fmt.Sprintf(`dkms remove -m %s -v %q --all`, kmodName, dVer)
 			_, err = exec.Command("bash", "-c", dkmsRmCmdArgs).Output() //nolint:gosec
 			if err == nil {
-				printer.Logger.Info("OK! Removing succeeded.", args, printer.Logger.Args("version", dVer))
+				printer.Logger.Info("OK! Removing succeeded.", printer.Logger.Args("version", dVer))
 			} else {
-				printer.Logger.Warn("Removing failed.", args, printer.Logger.Args("version", dVer))
+				printer.Logger.Warn("Removing failed.", printer.Logger.Args("version", dVer))
 			}
 		}
 	}
 	return nil
 }
 
+func (k *kmod) Load(printer *output.Printer, driverName string, fallback bool) error {
+	if fallback {
+		// Try to modprobe any existent version of the kmod; this is a fallback
+		// when both download and build of kmod fail.
+		printer.Logger.Info("Trying to load a pre existent system module, if present.")
+		_, err := exec.Command("modprobe", driverName).Output() //nolint:gosec
+		if err == nil {
+			printer.Logger.Info("Success: module found and loaded with modprobe.")
+		} else {
+			printer.Logger.Error("Consider compiling your own driver and loading it or getting in touch with the Falco community.")
+		}
+		return err
+	}
+
+	chconCmdArgs := fmt.Sprintf(`chcon -t modules_object_t %q`, driverName)
+	// We don't want to catch any error from this call
+	// chcon(1): change file SELinux security context
+	_, _ = exec.Command("bash", "-c", chconCmdArgs).Output() //nolint:gosec
+	_, err := exec.Command("insmod", driverName).Output()    //nolint:gosec
+	if err == nil {
+		printer.Logger.Info("Success: module found and loaded in dkms.")
+	} else {
+		printer.Logger.Warn("Unable to insmod module.")
+	}
+	return err
+}
+
 func (k *kmod) Extension() string {
 	return ".ko"
 }

pkg/driver/type/modernbpf.go

@@ -31,6 +31,10 @@ func (m *modernBpf) Prepare(_ *output.Printer, _ string) error {
 	return nil
 }
 
+func (m *modernBpf) Load(_ *output.Printer, _ string, _ bool) error {
+	return nil
+}
+
 func (m *modernBpf) Extension() string {
 	return ""
 }

pkg/driver/type/type.go

@@ -27,6 +27,7 @@ var driverTypes = map[string]DriverType{}
 type DriverType interface {
 	String() string
 	Prepare(printer *output.Printer, driverName string) error
+	Load(printer *output.Printer, driverName string, fallback bool) error
 	Extension() string
 	HasArtifacts() bool
 }