feat: start enabling SELinux

Part of: #9127 Label executables and processes, build, load and manage SELinux policy, enable audit support. Labeling filesystems, devices and runtime files will be done in further changes, see the full PR. Signed-off-by: Dmitry Sharshakov <[email protected]>
siderolabs · Nov 4, 2024 · 960a040 · 960a040
1 parent 7f3aaa2
commit 960a040
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diff --git a/.dockerignore b/.dockerignore
@@ -1,5 +1,6 @@
 **
 !api
+!selinux
 !cmd
 !docs
 !hack

diff --git a/Dockerfile b/Dockerfile
@@ -375,6 +375,13 @@ COPY --from=embed-abbrev-generate /src/pkg/machinery/gendata/data /pkg/machinery
 COPY --from=embed-abbrev-generate /src/_out/talos-metadata /_out/talos-metadata
 COPY --from=embed-abbrev-generate /src/_out/signing_key.x509 /_out/signing_key.x509
 
+FROM tools AS selinux
+COPY ./internal/pkg/selinux/policy/* /selinux/
+RUN mkdir /policy; secilc -o /policy/policy.33 -f /policy/file_contexts -c 33 /selinux/**/*.cil -vvvvv -O
+
+FROM scratch AS selinux-generate
+COPY --from=selinux /policy /policy
+
 FROM scratch AS ipxe-generate
 COPY --from=pkg-ipxe-amd64 /usr/libexec/snp.efi /amd64/snp.efi
 COPY --from=pkg-ipxe-arm64 /usr/libexec/snp.efi /arm64/snp.efi
@@ -412,6 +419,7 @@ COPY --from=go-generate /src/pkg/machinery/config/types/ /pkg/machinery/config/t
 COPY --from=go-generate /src/pkg/machinery/nethelpers/ /pkg/machinery/nethelpers/
 COPY --from=go-generate /src/pkg/machinery/extensions/ /pkg/machinery/extensions/
 COPY --from=ipxe-generate / /pkg/provision/providers/vm/internal/ipxe/data/ipxe/
+COPY --from=selinux-generate / /internal/pkg/selinux/
 COPY --from=embed-abbrev / /
 COPY --from=pkg-ca-certificates /etc/ssl/certs/ca-certificates /internal/app/machined/pkg/controllers/secrets/data/
 COPY --from=microsoft-key-keys / /internal/pkg/secureboot/database/certs/
@@ -429,6 +437,7 @@ COPY --from=generate /pkg/imager/ ./pkg/imager/
 COPY --from=generate /pkg/machinery/ ./pkg/machinery/
 COPY --from=generate /internal/app/machined/pkg/controllers/secrets/data/ ./internal/app/machined/pkg/controllers/secrets/data/
 COPY --from=generate /internal/pkg/secureboot/database/certs/ ./internal/pkg/secureboot/database/certs/
+COPY --from=generate /internal/pkg/selinux/ ./internal/pkg/selinux/
 COPY --from=embed / ./
 RUN --mount=type=cache,target=/.cache go list all >/dev/null
 WORKDIR /src/pkg/machinery
@@ -809,13 +818,19 @@ FROM rootfs-base-arm64 AS rootfs-squashfs-arm64
 ARG ZSTD_COMPRESSION_LEVEL
 RUN find /rootfs -print0 \
     | xargs -0r touch --no-dereference --date="@${SOURCE_DATE_EPOCH}"
-RUN mksquashfs /rootfs /rootfs.sqsh -all-root -noappend -comp zstd -Xcompression-level ${ZSTD_COMPRESSION_LEVEL} -no-progress
+COPY --from=selinux-generate /policy/file_contexts /file_contexts
+COPY ./hack/labeled-squashfs.sh /
+ENV SHELL=/toolchain/bin/bash
+RUN fakeroot /labeled-squashfs.sh /rootfs /rootfs.sqsh /file_contexts ${ZSTD_COMPRESSION_LEVEL}
 
 FROM rootfs-base-amd64 AS rootfs-squashfs-amd64
 ARG ZSTD_COMPRESSION_LEVEL
 RUN find /rootfs -print0 \
     | xargs -0r touch --no-dereference --date="@${SOURCE_DATE_EPOCH}"
-RUN mksquashfs /rootfs /rootfs.sqsh -all-root -noappend -comp zstd -Xcompression-level ${ZSTD_COMPRESSION_LEVEL} -no-progress
+COPY --from=selinux-generate /policy/file_contexts /file_contexts
+COPY ./hack/labeled-squashfs.sh /
+ENV SHELL=/toolchain/bin/bash
+RUN fakeroot /labeled-squashfs.sh /rootfs /rootfs.sqsh /file_contexts ${ZSTD_COMPRESSION_LEVEL}
 
 FROM scratch AS squashfs-arm64
 COPY --from=rootfs-squashfs-arm64 /rootfs.sqsh /

diff --git a/hack/labeled-squashfs.sh b/hack/labeled-squashfs.sh
@@ -0,0 +1,6 @@
+#!/toolchain/bin/bash
+
+set -e
+# set SELinux labels for files according to file_contexts supplied
+/toolchain/sbin/setfiles -r $1 -F -vv $3 $1
+mksquashfs $1 $2 -all-root -noappend -comp zstd -Xcompression-level $4 -no-progress
diff --git a/internal/app/machined/pkg/runtime/v1alpha1/v1alpha1_sequencer_tasks.go b/internal/app/machined/pkg/runtime/v1alpha1/v1alpha1_sequencer_tasks.go
@@ -63,6 +63,7 @@ import (
 	"github.com/siderolabs/talos/internal/pkg/partition"
 	"github.com/siderolabs/talos/internal/pkg/secureboot"
 	"github.com/siderolabs/talos/internal/pkg/secureboot/tpm2"
+	"github.com/siderolabs/talos/internal/pkg/selinux"
 	"github.com/siderolabs/talos/internal/pkg/zboot"
 	"github.com/siderolabs/talos/pkg/conditions"
 	"github.com/siderolabs/talos/pkg/images"
@@ -620,6 +621,10 @@ func WriteUdevRules(runtime.Sequence, any) (runtime.TaskExecutionFunc, string) {
 			return fmt.Errorf("failed writing custom udev rules: %w", err)
 		}
 
+		if err = selinux.SetLabel(constants.UdevRulesPath, constants.UdevRulesLabel); err != nil {
+			return fmt.Errorf("failed labeling custom udev rules: %w", err)
+		}
+
 		if len(rules) > 0 {
 			if _, err := cmd.RunContext(ctx, "/sbin/udevadm", "control", "--reload"); err != nil {
 				return err

diff --git a/internal/app/machined/pkg/system/runner/containerd/containerd.go b/internal/app/machined/pkg/system/runner/containerd/containerd.go
@@ -23,6 +23,8 @@ import (
 	"github.com/siderolabs/talos/internal/app/machined/pkg/system/events"
 	"github.com/siderolabs/talos/internal/app/machined/pkg/system/runner"
 	"github.com/siderolabs/talos/internal/pkg/cgroup"
+	"github.com/siderolabs/talos/internal/pkg/selinux"
+	"github.com/siderolabs/talos/pkg/machinery/constants"
 )
 
 // containerdRunner is a runner.Runner that runs container in containerd.
@@ -341,6 +343,20 @@ func (c *containerdRunner) newOCISpecOpts(image oci.Image) []oci.SpecOpts {
 		)
 	}
 
+	if selinux.IsEnabled() {
+		if c.opts.SelinuxLabel != "" {
+			specOpts = append(
+				specOpts,
+				oci.WithSelinuxLabel(c.opts.SelinuxLabel),
+			)
+		} else {
+			specOpts = append(
+				specOpts,
+				oci.WithSelinuxLabel(constants.SelinuxLabelUnconfinedSysContainer),
+			)
+		}
+	}
+
 	return specOpts
 }
 

diff --git a/internal/app/machined/pkg/system/runner/process/process.go b/internal/app/machined/pkg/system/runner/process/process.go
@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"log"
 	"os"
 	"path"
 	"slices"
@@ -30,6 +31,7 @@ import (
 	"github.com/siderolabs/talos/internal/app/machined/pkg/system/events"
 	"github.com/siderolabs/talos/internal/app/machined/pkg/system/runner"
 	"github.com/siderolabs/talos/internal/pkg/cgroup"
+	"github.com/siderolabs/talos/internal/pkg/selinux"
 	"github.com/siderolabs/talos/pkg/machinery/constants"
 )
 
@@ -92,6 +94,7 @@ func (p *processRunner) Close() error {
 type commandWrapper struct {
 	launcher         *cap.Launcher
 	ctty             optional.Optional[int]
+	selinuxLabel     string
 	cgroupFile       *os.File
 	stdin            *os.File
 	stdout           *os.File
@@ -159,6 +162,22 @@ func beforeExecCallback(pa *syscall.ProcAttr, data any) error {
 		pa.Sys.CgroupFD = int(wrapper.cgroupFile.Fd())
 	}
 
+	// Use /proc/thread-self (Linux 3.17+) to avoid races between current
+	// process threads leading to loss of the domain transition
+	if selinux.IsEnabled() {
+		if wrapper.selinuxLabel != "" {
+			err := os.WriteFile("/proc/thread-self/attr/exec", []byte(wrapper.selinuxLabel), 0o777)
+			if err != nil {
+				log.Fatalf("%s", err)
+			}
+		} else {
+			err := os.WriteFile("/proc/thread-self/attr/exec", []byte(constants.SelinuxLabelUnconfinedService), 0o777)
+			if err != nil {
+				log.Fatalf("%s", err)
+			}
+		}
+	}
+
 	return nil
 }
 
@@ -266,6 +285,7 @@ func (p *processRunner) build() (commandWrapper, error) {
 	wrapper.afterStart = func() { xslices.Map(afterStartClosers, io.Closer.Close) }
 	wrapper.afterTermination = closeLogging
 	wrapper.ctty = p.opts.Ctty
+	wrapper.selinuxLabel = p.opts.SelinuxLabel
 
 	cgroupFdSupported := false
 

diff --git a/internal/app/machined/pkg/system/runner/runner.go b/internal/app/machined/pkg/system/runner/runner.go
@@ -70,6 +70,8 @@ type Options struct {
 	OverrideSeccompProfile func(*specs.LinuxSeccomp)
 	// DroppedCapabilities is the list of capabilities to drop.
 	DroppedCapabilities []string
+	// SelinuxLabel is the SELinux label to be assigned
+	SelinuxLabel string
 	// StdinFile is the path to the file to use as stdin.
 	StdinFile string
 	// StdoutFile is the path to the file to use as stdout.
@@ -175,6 +177,13 @@ func WithCgroupPath(path string) Option {
 	}
 }
 
+// WithSelinuxLabel sets the SELinux label.
+func WithSelinuxLabel(label string) Option {
+	return func(args *Options) {
+		args.SelinuxLabel = label
+	}
+}
+
 // WithCustomSeccompProfile sets the function to override seccomp profile.
 func WithCustomSeccompProfile(override func(*specs.LinuxSeccomp)) Option {
 	return func(args *Options) {

diff --git a/internal/app/machined/pkg/system/services/apid.go b/internal/app/machined/pkg/system/services/apid.go
@@ -196,6 +196,7 @@ func (o *APID) Runner(r runtime.Runtime) (runner.Runner, error) {
 		runner.WithContainerdAddress(constants.SystemContainerdAddress),
 		runner.WithEnv(env),
 		runner.WithCgroupPath(constants.CgroupApid),
+		runner.WithSelinuxLabel(constants.SelinuxLabelApid),
 		runner.WithOCISpecOpts(
 			oci.WithDroppedCapabilities(cap.Known()),
 			oci.WithHostNamespace(specs.NetworkNamespace),

diff --git a/internal/app/machined/pkg/system/services/containerd.go b/internal/app/machined/pkg/system/services/containerd.go
@@ -112,6 +112,7 @@ func (c *Containerd) Runner(r runtime.Runtime) (runner.Runner, error) {
 		)),
 		runner.WithOOMScoreAdj(-999),
 		runner.WithCgroupPath(constants.CgroupSystemRuntime),
+		runner.WithSelinuxLabel(constants.SelinuxLabelSystemRuntime),
 		runner.WithDroppedCapabilities(constants.DefaultDroppedCapabilities),
 	),
 		restart.WithType(restart.Forever),

diff --git a/internal/app/machined/pkg/system/services/cri.go b/internal/app/machined/pkg/system/services/cri.go
@@ -106,6 +106,7 @@ func (c *CRI) Runner(r runtime.Runtime) (runner.Runner, error) {
 		)),
 		runner.WithOOMScoreAdj(-500),
 		runner.WithCgroupPath(constants.CgroupPodRuntime),
+		runner.WithSelinuxLabel(constants.SelinuxLabelPodRuntime),
 		runner.WithDroppedCapabilities(constants.DefaultDroppedCapabilities),
 	),
 		restart.WithType(restart.Forever),

diff --git a/internal/app/machined/pkg/system/services/dashboard.go b/internal/app/machined/pkg/system/services/dashboard.go
@@ -69,6 +69,7 @@ func (d *Dashboard) Runner(r runtime.Runtime) (runner.Runner, error) {
 		runner.WithCtty(0),
 		runner.WithOOMScoreAdj(-400),
 		runner.WithDroppedCapabilities(capability.AllCapabilitiesSetLowercase()),
+		runner.WithSelinuxLabel(constants.SelinuxLabelDashboard),
 		runner.WithCgroupPath(constants.CgroupDashboard),
 		runner.WithUID(constants.DashboardUserID),
 	),

diff --git a/internal/app/machined/pkg/system/services/etcd.go b/internal/app/machined/pkg/system/services/etcd.go
@@ -220,6 +220,7 @@ func (e *Etcd) Runner(r runtime.Runtime) (runner.Runner, error) {
 		runner.WithContainerImage(e.imgRef),
 		runner.WithEnv(env),
 		runner.WithCgroupPath(constants.CgroupEtcd),
+		runner.WithSelinuxLabel(constants.SELinuxLabelEtcd),
 		runner.WithOCISpecOpts(
 			oci.WithDroppedCapabilities(cap.Known()),
 			oci.WithHostNamespace(specs.NetworkNamespace),

diff --git a/internal/app/machined/pkg/system/services/kubelet.go b/internal/app/machined/pkg/system/services/kubelet.go
@@ -164,6 +164,7 @@ func (k *Kubelet) Runner(r runtime.Runtime) (runner.Runner, error) {
 		runner.WithContainerImage(k.imgRef),
 		runner.WithEnv(environment.Get(r.Config())),
 		runner.WithCgroupPath(constants.CgroupKubelet),
+		runner.WithSelinuxLabel(constants.SelinuxLabelKubelet),
 		runner.WithOCISpecOpts(
 			containerd.WithRootfsPropagation("shared"),
 			oci.WithMounts(mounts),
@@ -174,7 +175,6 @@ func (k *Kubelet) Runner(r runtime.Runtime) (runner.Runner, error) {
 			oci.WithReadonlyPaths(nil),
 			oci.WithWriteableSysfs,
 			oci.WithWriteableCgroupfs,
-			oci.WithSelinuxLabel(""),
 			oci.WithApparmorProfile(""),
 			oci.WithAllDevicesAllowed,
 			oci.WithCapabilities(capability.AllGrantableCapabilities()), // TODO: kubelet doesn't need all of these, we should consider limiting capabilities

diff --git a/internal/app/machined/pkg/system/services/trustd.go b/internal/app/machined/pkg/system/services/trustd.go
@@ -159,6 +159,7 @@ func (t *Trustd) Runner(r runtime.Runtime) (runner.Runner, error) {
 		runner.WithContainerdAddress(constants.SystemContainerdAddress),
 		runner.WithEnv(env),
 		runner.WithCgroupPath(constants.CgroupTrustd),
+		runner.WithSelinuxLabel(constants.SelinuxLabelTrustd),
 		runner.WithOCISpecOpts(
 			oci.WithDroppedCapabilities(cap.Known()),
 			oci.WithHostNamespace(specs.NetworkNamespace),

diff --git a/internal/app/machined/pkg/system/services/udevd.go b/internal/app/machined/pkg/system/services/udevd.go
@@ -88,6 +88,7 @@ func (c *Udevd) Runner(r runtime.Runtime) (runner.Runner, error) {
 		args,
 		runner.WithLoggingManager(r.Logging()),
 		runner.WithCgroupPath(constants.CgroupUdevd),
+		runner.WithSelinuxLabel(constants.SelinuxLabelUdevd),
 		runner.WithDroppedCapabilities(constants.UdevdDroppedCapabilities),
 		runner.WithEnv([]string{
 			// append a default value for XDG_RUNTIME_DIR for the services running on the host