feat: Add support for Landlock based Sandbox for Linux (#238)

* feat: Initial implementation of landlock based sandbox driver

* fix: Handle seccom probe failure

* fix: Remove unnecessary seccomp probe

* fix: Use file based policy load

* fix: Keep bpf filter in memory

* fix: Use TSYNC for seccom filter

* fix: Use TSYNC for seccom filter

* fix: Update landlock translator

* fix: Landlock sandbox implementation

* fix: Landlock + seccomp based sandboxing on Linux

* fix: Misc fixes

* fix: Cleanup sandbox files

* fix: Handle mandatory deny API change post merge

* fix: Landlock write access translation

* chore: Fix linter issues

* ci: Use /tmp for npm cache for landlock

cmd/landlock/landlock_sandbox_exec_linux.go

@@ -0,0 +1,33 @@
+//go:build linux
+
+package landlock
+
+import (
+	"github.com/safedep/pmg/sandbox/platform"
+	"github.com/spf13/cobra"
+)
+
+// NewLandlockSandboxExecCommand returns the hidden Cobra command used as the
+// helper process entry point for the Landlock sandbox driver.
+func NewLandlockSandboxExecCommand() *cobra.Command {
+	var policyFile string
+	var auditSocket string
+
+	cmd := &cobra.Command{
+		Use:    "__landlock_sandbox_exec",
+		Hidden: true,
+		// Skip parent pmg initialization (config, event log, analytics) —
+		// RunLandlockHelper sets up its own minimal logger.
+		PersistentPreRun: func(cmd *cobra.Command, args []string) {},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return platform.RunLandlockHelper(policyFile, auditSocket, args)
+		},
+	}
+
+	cmd.Flags().StringVar(&policyFile, "policy-file", "", "Path to policy JSON file")
+	cmd.Flags().StringVar(&auditSocket, "audit-socket", "", "Path to audit unix socket")
+	_ = cmd.MarkFlagRequired("policy-file")
+	_ = cmd.MarkFlagRequired("audit-socket")
+
+	return cmd
+}

cmd/landlock/landlock_sandbox_exec_other.go

@@ -0,0 +1,9 @@
+//go:build !linux
+
+package landlock
+
+import "github.com/spf13/cobra"
+
+// NewLandlockSandboxExecCommand returns nil on non-Linux platforms where
+// Landlock is not available.
+func NewLandlockSandboxExecCommand() *cobra.Command { return nil }

cmd/landlock/landlock_shim_linux.go

@@ -0,0 +1,38 @@
+//go:build linux
+
+package landlock
+
+import (
+	"github.com/safedep/pmg/sandbox/platform"
+	"github.com/spf13/cobra"
+)
+
+// NewLandlockShimCommand returns the hidden Cobra command used as the
+// inside-user-namespace shim. The helper process (pmg __landlock_sandbox_exec)
+// clones a child with CLONE_NEWUSER + uid/gid mapping (0 -> host uid) so the
+// shim boots as uid 0 inside the ns with CAP_SYS_ADMIN. The shim installs the
+// seccomp filter WITHOUT PR_SET_NO_NEW_PRIVS (allowed by CAP_SYS_ADMIN in the
+// ns) and applies Landlock; this keeps the shim (and every descendant) with
+// dumpable=1, so the helper can open /proc/<pid>/mem to resolve openat(2)
+// path arguments for seccomp-notify.
+func NewLandlockShimCommand() *cobra.Command {
+	var policyFile string
+	var notifySocketFd int
+
+	cmd := &cobra.Command{
+		Use:                "__landlock_shim",
+		Hidden:             true,
+		DisableFlagParsing: false,
+		// Skip parent pmg initialization — the shim re-execs almost
+		// immediately and does not need config/analytics/etc.
+		PersistentPreRun: func(cmd *cobra.Command, args []string) {},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return platform.RunLandlockShim(policyFile, notifySocketFd, args)
+		},
+	}
+	cmd.Flags().StringVar(&policyFile, "policy-file", "", "Path to policy JSON file")
+	cmd.Flags().IntVar(&notifySocketFd, "notify-socket-fd", 0, "FD of socketpair end used to send the seccomp notify fd to the supervisor")
+	_ = cmd.MarkFlagRequired("policy-file")
+	_ = cmd.MarkFlagRequired("notify-socket-fd")
+	return cmd
+}

cmd/landlock/landlock_shim_other.go

@@ -0,0 +1,8 @@
+//go:build !linux
+
+package landlock
+
+import "github.com/spf13/cobra"
+
+// NewLandlockShimCommand returns nil on non-Linux platforms.
+func NewLandlockShimCommand() *cobra.Command { return nil }