package roothelper import ( "os" "path/filepath" "testing" "banger/internal/daemon/dmsnap" "banger/internal/firecracker" "banger/internal/paths" ) func TestValidateDMDevicePath(t *testing.T) { t.Parallel() for _, tc := range []struct { name string path string ok bool }{ {name: "valid", path: "/dev/mapper/fc-rootfs-test", ok: true}, {name: "wrong_prefix", path: "/dev/mapper/not-banger", ok: false}, {name: "wrong_dir", path: "/tmp/fc-rootfs-test", ok: false}, {name: "relative", path: "fc-rootfs-test", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateDMDevicePath(tc.path) if tc.ok && err != nil { t.Fatalf("validateDMDevicePath(%q) = %v, want nil", tc.path, err) } if !tc.ok && err == nil { t.Fatalf("validateDMDevicePath(%q) succeeded, want error", tc.path) } }) } } func TestValidateFirecrackerPID(t *testing.T) { t.Parallel() if err := validateFirecrackerPID(0); err == nil { t.Fatal("validateFirecrackerPID(0) succeeded, want error") } if err := validateFirecrackerPID(-1); err == nil { t.Fatal("validateFirecrackerPID(-1) succeeded, want error") } // Self pid points at the go test binary, whose cmdline does not // contain "firecracker" — rejection proves the helper would refuse // to kill arbitrary host processes. if err := validateFirecrackerPID(os.Getpid()); err == nil { t.Fatal("validateFirecrackerPID(test pid) succeeded, want error") } // PID 1 is init/systemd on Linux — a juicy target for a compromised // daemon, and definitely not firecracker. Make sure we'd refuse. if err := validateFirecrackerPID(1); err == nil { t.Fatal("validateFirecrackerPID(1) succeeded, want error") } } // TestValidateRootExecutableRejectsSymlink pins the O_NOFOLLOW // guarantee: even if the path string passes a textual check, a symlink // at the leaf is refused before we ever stat the target. func TestValidateRootExecutableRejectsSymlink(t *testing.T) { t.Parallel() dir := t.TempDir() regular := filepath.Join(dir, "real") if err := os.WriteFile(regular, []byte{}, 0o755); err != nil { t.Fatalf("write regular: %v", err) } link := filepath.Join(dir, "link") if err := os.Symlink(regular, link); err != nil { t.Fatalf("symlink: %v", err) } if err := validateRootExecutable(link); err == nil { t.Fatal("validateRootExecutable(symlink) succeeded, want error") } } // TestValidateRootExecutableRejectsNonRootOwned exercises the Fstat // uid check on a file the test user just created: it can't possibly // be uid 0, so the validator must refuse it. This is the regression // guard against the previous os.Stat code path drifting back in. func TestValidateRootExecutableRejectsNonRootOwned(t *testing.T) { t.Parallel() if os.Getuid() == 0 { t.Skip("test runs as root; cannot construct a non-root-owned file in a tempdir we can write") } path := filepath.Join(t.TempDir(), "binary") if err := os.WriteFile(path, []byte{}, 0o755); err != nil { t.Fatalf("write: %v", err) } err := validateRootExecutable(path) if err == nil { t.Fatal("validateRootExecutable(user-owned) succeeded, want error") } if !contains(err.Error(), "root-owned") { t.Fatalf("err = %v, want root-owned rejection", err) } } func TestValidateRootExecutableRejectsGroupWritable(t *testing.T) { t.Parallel() if os.Getuid() == 0 { t.Skip("test runs as root; can't construct a non-root-owned file") } path := filepath.Join(t.TempDir(), "binary") if err := os.WriteFile(path, []byte{}, 0o775); err != nil { t.Fatalf("write: %v", err) } err := validateRootExecutable(path) if err == nil { t.Fatal("validateRootExecutable(group-writable) succeeded, want error") } } // contains is a local substring helper that mirrors strings.Contains // without pulling in the package — kept tiny so the test file's // dependency surface stays close to the thing being tested. func contains(s, sub string) bool { for i := 0; i+len(sub) <= len(s); i++ { if s[i:i+len(sub)] == sub { return true } } return false } func TestValidateSignalName(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "TERM", arg: "TERM", ok: true}, {name: "SIGTERM", arg: "SIGTERM", ok: true}, {name: "lowercase_kill", arg: "kill", ok: true}, {name: "with_whitespace", arg: " HUP ", ok: true}, {name: "USR1", arg: "USR1", ok: true}, {name: "ABRT", arg: "ABRT", ok: true}, {name: "empty", arg: "", ok: false}, {name: "numeric_9", arg: "9", ok: false}, {name: "STOP_DoS", arg: "STOP", ok: false}, {name: "CONT", arg: "CONT", ok: false}, {name: "realtime", arg: "RTMIN+1", ok: false}, {name: "garbage", arg: "FOOBAR", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateSignalName(tc.arg) if tc.ok && err != nil { t.Fatalf("validateSignalName(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateSignalName(%q) succeeded, want error", tc.arg) } }) } } func TestExtractFirecrackerAPISock(t *testing.T) { t.Parallel() for _, tc := range []struct { name string cmdline string want string }{ {name: "long_form_space", cmdline: "firecracker --api-sock /run/banger/fc-abc.sock --id abc", want: "/run/banger/fc-abc.sock"}, {name: "long_form_equals", cmdline: "firecracker --api-sock=/run/banger/fc-abc.sock --id abc", want: "/run/banger/fc-abc.sock"}, {name: "short_form", cmdline: "firecracker -a /run/banger/fc-abc.sock --id abc", want: "/run/banger/fc-abc.sock"}, {name: "absent", cmdline: "firecracker --id abc", want: ""}, {name: "trailing_flag", cmdline: "firecracker --api-sock", want: ""}, {name: "empty", cmdline: "", want: ""}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() got := extractFirecrackerAPISock(tc.cmdline) if got != tc.want { t.Fatalf("extractFirecrackerAPISock(%q) = %q, want %q", tc.cmdline, got, tc.want) } }) } } func TestPathIsUnder(t *testing.T) { t.Parallel() for _, tc := range []struct { name string p string root string want bool }{ {name: "exact", p: "/var/lib/banger", root: "/var/lib/banger", want: true}, {name: "nested", p: "/var/lib/banger/jail/x", root: "/var/lib/banger", want: true}, {name: "sibling", p: "/var/lib/banger-other", root: "/var/lib/banger", want: false}, {name: "outside", p: "/etc/passwd", root: "/var/lib/banger", want: false}, {name: "empty_root", p: "/anywhere", root: "", want: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() if got := pathIsUnder(tc.p, tc.root); got != tc.want { t.Fatalf("pathIsUnder(%q, %q) = %v, want %v", tc.p, tc.root, got, tc.want) } }) } } func TestValidateLoopDevicePath(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "loop0", arg: "/dev/loop0", ok: true}, {name: "loop12", arg: "/dev/loop12", ok: true}, {name: "no_index", arg: "/dev/loop", ok: false}, {name: "non_numeric", arg: "/dev/loop-x", ok: false}, {name: "wrong_prefix", arg: "/dev/sda1", ok: false}, {name: "empty", arg: "", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateLoopDevicePath(tc.arg) if tc.ok && err != nil { t.Fatalf("validateLoopDevicePath(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateLoopDevicePath(%q) succeeded, want error", tc.arg) } }) } } func TestValidateDMRemoveTarget(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "dm_name", arg: "fc-rootfs-abc", ok: true}, {name: "dm_device_path", arg: "/dev/mapper/fc-rootfs-abc", ok: true}, {name: "wrong_prefix", arg: "not-banger", ok: false}, {name: "device_wrong_prefix", arg: "/dev/mapper/not-banger", ok: false}, {name: "empty", arg: "", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateDMRemoveTarget(tc.arg) if tc.ok && err != nil { t.Fatalf("validateDMRemoveTarget(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateDMRemoveTarget(%q) succeeded, want error", tc.arg) } }) } } func TestValidateDMSnapshotHandles(t *testing.T) { t.Parallel() // Empty handles are tolerated — the dmsnap layer treats every // missing field as a no-op for that step. if err := validateDMSnapshotHandles(dmsnap.Handles{}); err != nil { t.Fatalf("validateDMSnapshotHandles(empty) = %v, want nil", err) } good := dmsnap.Handles{ BaseLoop: "/dev/loop0", COWLoop: "/dev/loop1", DMName: "fc-rootfs-abc", DMDev: "/dev/mapper/fc-rootfs-abc", } if err := validateDMSnapshotHandles(good); err != nil { t.Fatalf("validateDMSnapshotHandles(good) = %v, want nil", err) } for _, tc := range []struct { name string mutate func(dmsnap.Handles) dmsnap.Handles wantErr bool }{ {name: "bad_dm_name", mutate: func(h dmsnap.Handles) dmsnap.Handles { h.DMName = "rogue" return h }, wantErr: true}, {name: "bad_dm_device", mutate: func(h dmsnap.Handles) dmsnap.Handles { h.DMDev = "/dev/sda1" return h }, wantErr: true}, {name: "bad_base_loop", mutate: func(h dmsnap.Handles) dmsnap.Handles { h.BaseLoop = "/dev/sda1" return h }, wantErr: true}, {name: "bad_cow_loop", mutate: func(h dmsnap.Handles) dmsnap.Handles { h.COWLoop = "/etc/shadow" return h }, wantErr: true}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateDMSnapshotHandles(tc.mutate(good)) if tc.wantErr && err == nil { t.Fatalf("validateDMSnapshotHandles(%s) succeeded, want error", tc.name) } if !tc.wantErr && err != nil { t.Fatalf("validateDMSnapshotHandles(%s) = %v, want nil", tc.name, err) } }) } } // TestValidateManagedPathRejectsSymlinkLeaf pins the leaf-symlink // rejection: even when the path string sits inside a managed root, a // symlink at the final component must be refused. Otherwise a // daemon-UID attacker could plant `/foo -> /etc/shadow` and // get the helper to drive privileged tooling against host files. func TestValidateManagedPathRejectsSymlinkLeaf(t *testing.T) { t.Parallel() srv := &Server{} root := t.TempDir() target := filepath.Join(t.TempDir(), "outside") if err := os.WriteFile(target, []byte("secret"), 0o600); err != nil { t.Fatalf("write target: %v", err) } link := filepath.Join(root, "leak") if err := os.Symlink(target, link); err != nil { t.Fatalf("symlink: %v", err) } err := srv.validateManagedPath(link, root) if err == nil { t.Fatal("validateManagedPath(symlink leaf) succeeded, want error") } } // TestValidateManagedPathRejectsSymlinkIntermediate pins ancestor // symlink rejection. Without the walk, an attacker plants // `/dir -> /etc` and a path like `/dir/passwd` // passes the textual prefix check but resolves to /etc/passwd at op // time. func TestValidateManagedPathRejectsSymlinkIntermediate(t *testing.T) { t.Parallel() srv := &Server{} root := t.TempDir() target := t.TempDir() link := filepath.Join(root, "redirect") if err := os.Symlink(target, link); err != nil { t.Fatalf("symlink: %v", err) } err := srv.validateManagedPath(filepath.Join(link, "passwd"), root) if err == nil { t.Fatal("validateManagedPath(symlink intermediate) succeeded, want error") } } // TestValidateManagedPathToleratesMissingLeaf confirms ENOENT does // not flip the validator into a fail. Several callers pass paths // firecracker (or the helper's own staging) creates AFTER validation // — sockets, log files, kernel hard-link targets — and a strict // existence check would break those flows. func TestValidateManagedPathToleratesMissingLeaf(t *testing.T) { t.Parallel() srv := &Server{} root := t.TempDir() missing := filepath.Join(root, "deeper", "not-yet") if err := srv.validateManagedPath(missing, root); err != nil { t.Fatalf("validateManagedPath(missing leaf) = %v, want nil", err) } } // TestValidateManagedPathPassesPlainSubpath is the happy path: a // regular file inside a real subdir should sail through the new walk. func TestValidateManagedPathPassesPlainSubpath(t *testing.T) { t.Parallel() srv := &Server{} root := t.TempDir() subdir := filepath.Join(root, "vms", "abc") if err := os.MkdirAll(subdir, 0o755); err != nil { t.Fatalf("mkdir: %v", err) } leaf := filepath.Join(subdir, "rootfs.ext4") if err := os.WriteFile(leaf, []byte("data"), 0o644); err != nil { t.Fatalf("write leaf: %v", err) } if err := srv.validateManagedPath(leaf, root); err != nil { t.Fatalf("validateManagedPath(plain subpath) = %v, want nil", err) } } func TestValidateBangerBridgeName(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "default", arg: "br-fc", ok: true}, {name: "suffixed", arg: "br-fc-alt", ok: true}, {name: "with_whitespace", arg: " br-fc ", ok: true}, {name: "wrong_prefix", arg: "br0", ok: false}, {name: "host_iface", arg: "eth0", ok: false}, {name: "docker", arg: "docker0", ok: false}, {name: "loopback", arg: "lo", ok: false}, {name: "empty", arg: "", ok: false}, {name: "br_dash_only", arg: "br-", ok: false}, // not "br-fc" exactly {name: "almost_match", arg: "br-fcx", ok: false}, {name: "with_slash", arg: "br-fc/x", ok: false}, {name: "too_long", arg: "br-fc-aaaaaaaaaa", ok: false}, // 16 chars } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateBangerBridgeName(tc.arg) if tc.ok && err != nil { t.Fatalf("validateBangerBridgeName(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateBangerBridgeName(%q) succeeded, want error", tc.arg) } }) } } func TestValidateCIDRPrefix(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "default_24", arg: "24", ok: true}, {name: "min_8", arg: "8", ok: true}, {name: "max_32", arg: "32", ok: true}, {name: "with_whitespace", arg: " 16 ", ok: true}, {name: "below_min", arg: "7", ok: false}, {name: "above_max", arg: "33", ok: false}, {name: "non_numeric", arg: "abc", ok: false}, {name: "ipv6_prefix", arg: "64", ok: false}, // outside [8, 32] {name: "with_slash", arg: "/24", ok: false}, {name: "empty", arg: "", ok: false}, {name: "negative", arg: "-1", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateCIDRPrefix(tc.arg) if tc.ok && err != nil { t.Fatalf("validateCIDRPrefix(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateCIDRPrefix(%q) succeeded, want error", tc.arg) } }) } } func TestValidateNetworkConfig(t *testing.T) { t.Parallel() good := NetworkConfig{ BridgeName: "br-fc", BridgeIP: "172.16.0.1", CIDR: "24", } if err := validateNetworkConfig(good); err != nil { t.Fatalf("validateNetworkConfig(default) = %v, want nil", err) } for _, tc := range []struct { name string mutate func(NetworkConfig) NetworkConfig }{ {name: "bad_bridge", mutate: func(c NetworkConfig) NetworkConfig { c.BridgeName = "eth0"; return c }}, {name: "bad_ip", mutate: func(c NetworkConfig) NetworkConfig { c.BridgeIP = "::1"; return c }}, {name: "bad_cidr", mutate: func(c NetworkConfig) NetworkConfig { c.CIDR = "/24"; return c }}, {name: "missing_ip", mutate: func(c NetworkConfig) NetworkConfig { c.BridgeIP = ""; return c }}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() if err := validateNetworkConfig(tc.mutate(good)); err == nil { t.Fatalf("validateNetworkConfig(%s) succeeded, want error", tc.name) } }) } } func TestValidateLinuxIfaceName(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "typical_bridge", arg: "br-banger", ok: true}, {name: "uplink", arg: "enp5s0", ok: true}, {name: "max_len", arg: "a234567890abcde", ok: true}, // 15 chars {name: "empty", arg: "", ok: false}, {name: "too_long", arg: "a234567890abcdef", ok: false}, {name: "with_slash", arg: "br/0", ok: false}, {name: "with_space", arg: "br 0", ok: false}, {name: "with_colon", arg: "br:0", ok: false}, {name: "dot", arg: ".", ok: false}, {name: "dotdot", arg: "..", ok: false}, {name: "control_char", arg: "br\x01", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateLinuxIfaceName(tc.arg) if tc.ok && err != nil { t.Fatalf("validateLinuxIfaceName(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateLinuxIfaceName(%q) succeeded, want error", tc.arg) } }) } } func TestValidateIPv4(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "valid", arg: "172.16.0.2", ok: true}, {name: "with_whitespace", arg: " 10.0.0.1 ", ok: true}, {name: "empty", arg: "", ok: false}, {name: "ipv6", arg: "::1", ok: false}, {name: "garbage", arg: "not-an-ip", ok: false}, {name: "with_cidr", arg: "10.0.0.1/24", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateIPv4(tc.arg) if tc.ok && err != nil { t.Fatalf("validateIPv4(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateIPv4(%q) succeeded, want error", tc.arg) } }) } } func TestValidateResolverAddr(t *testing.T) { t.Parallel() for _, tc := range []struct { name string arg string ok bool }{ {name: "ipv4", arg: "192.168.1.1", ok: true}, {name: "ipv6", arg: "fe80::1", ok: true}, {name: "empty", arg: "", ok: false}, {name: "garbage", arg: "resolver.example", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := validateResolverAddr(tc.arg) if tc.ok && err != nil { t.Fatalf("validateResolverAddr(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateResolverAddr(%q) succeeded, want error", tc.arg) } }) } } func TestValidateExt4ImagePath(t *testing.T) { t.Parallel() srv := &Server{} stateDir := paths.ResolveSystem().StateDir for _, tc := range []struct { name string arg string ok bool }{ {name: "managed_image", arg: filepath.Join(stateDir, "vms", "abc", "rootfs.ext4"), ok: true}, {name: "managed_dm_device", arg: "/dev/mapper/fc-rootfs-test", ok: true}, {name: "outside_state", arg: "/etc/shadow", ok: false}, {name: "wrong_dm", arg: "/dev/mapper/not-banger", ok: false}, {name: "relative", arg: "rootfs.ext4", ok: false}, {name: "empty", arg: "", ok: false}, } { tc := tc t.Run(tc.name, func(t *testing.T) { t.Parallel() err := srv.validateExt4ImagePath(tc.arg) if tc.ok && err != nil { t.Fatalf("validateExt4ImagePath(%q) = %v, want nil", tc.arg, err) } if !tc.ok && err == nil { t.Fatalf("validateExt4ImagePath(%q) succeeded, want error", tc.arg) } }) } } func TestValidateNotSymlink(t *testing.T) { t.Parallel() dir := t.TempDir() regular := filepath.Join(dir, "real") if err := os.WriteFile(regular, []byte("ok"), 0o600); err != nil { t.Fatalf("write regular: %v", err) } link := filepath.Join(dir, "link") if err := os.Symlink(regular, link); err != nil { t.Fatalf("symlink: %v", err) } if err := validateNotSymlink(regular); err != nil { t.Fatalf("validateNotSymlink(real) = %v, want nil", err) } if err := validateNotSymlink(link); err == nil { t.Fatal("validateNotSymlink(symlink) succeeded, want error") } if err := validateNotSymlink(filepath.Join(dir, "missing")); err == nil { t.Fatal("validateNotSymlink(missing) succeeded, want error") } // Symlink pointing into the system tree is the threat we care about. // A daemon-uid attacker plants this kind of link and hopes the helper // follows it; this test pins the rejection. hostileLink := filepath.Join(dir, "hostile") if err := os.Symlink("/etc/shadow", hostileLink); err != nil { t.Fatalf("symlink: %v", err) } if err := validateNotSymlink(hostileLink); err == nil { t.Fatal("validateNotSymlink(symlink-to-/etc/shadow) succeeded, want error") } } func TestValidateLaunchDrivePathAllowsManagedRootDMDevice(t *testing.T) { t.Parallel() srv := &Server{} if err := srv.validateLaunchDrivePath(firecracker.DriveConfig{ ID: "rootfs", Path: "/dev/mapper/fc-rootfs-test", IsRoot: true, }, "/var/lib/banger"); err != nil { t.Fatalf("validateLaunchDrivePath(root dm) = %v, want nil", err) } if err := srv.validateLaunchDrivePath(firecracker.DriveConfig{ ID: "work", Path: "/dev/mapper/fc-rootfs-test", IsRoot: false, }, "/var/lib/banger"); err == nil { t.Fatal("validateLaunchDrivePath(non-root dm) succeeded, want error") } }