fix: .minisign for signed releases

2026-06-22 20:03:27 +02:00
parent eba478471f
commit 0e041fac5e
15 changed files with 354 additions and 13 deletions
@@ -87,6 +87,31 @@ jobs:
            go build -ldflags="$LDFLAGS" -o dist/nadir-$VERSION-linux-arm64 ./cmd/server
          upx --best --lzma dist/nadir-$VERSION-linux-amd64 dist/nadir-$VERSION-linux-arm64

+      - name: Sign checksums
+        if: steps.ver.outputs.release == 'true'
+        env:
+          MINISIGN_SECRET_KEY: ${{ secrets.MINISIGN_SECRET_KEY }}
+          MINISIGN_PASSWORD: ${{ secrets.MINISIGN_PASSWORD }}
+        run: |
+          set -ex
+          # Install the minisign CLI (pure Go, ~2s).
+          go install aead.dev/minisign/cmd/minisign@latest
+
+          # Generate sha256sums.txt from the built binaries.
+          cd dist
+          sha256sum nadir-* > sha256sums.txt
+          cat sha256sums.txt
+
+          # Write the secret key to a temp file, sign, shred it.
+          KEYFILE=$(mktemp)
+          trap 'shred -u "$KEYFILE" 2>/dev/null || rm -f "$KEYFILE"' EXIT
+          printf '%s\n' "$MINISIGN_SECRET_KEY" > "$KEYFILE"
+
+          # minisign -Sm signs the file, reading the key from -s and password
+          # from stdin. The .minisig is written next to the input file.
+          printf '%s' "$MINISIGN_PASSWORD" | minisign -Sm sha256sums.txt -s "$KEYFILE" -t "nadir release"
+          ls -la sha256sums.txt sha256sums.txt.minisig
+
      - name: Tag and release
        if: steps.ver.outputs.release == 'true'
        env:
@@ -11,4 +11,6 @@ config.yml
 # Editor
 *.swp

-CLAUDE.md
+CLAUDE.md
+
+minisign.key
@@ -28,3 +28,14 @@ var InstallScriptTemplate string
 //   go build -ldflags "-X nadir.Version=v1.2.3"
 // Local dev builds leave it as "dev".
 var Version = "dev"
+
+// ReleasePublicKey is the minisign public key whose signature on a release's
+// sha256sums.txt is required by the auto-updater. Replacing the binary is the
+// most dangerous thing nadir does, so it gets the strongest verification: the
+// updater downloads sha256sums.txt + .minisig from the configured Gitea repo,
+// verifies the signature against this embedded key, then verifies the binary's
+// sha256 against the file. Rotation requires a rebuild — intentional, so a
+// compromised Gitea instance cannot also rotate the trust anchor.
+//
+//go:embed minisign.pub
+var ReleasePublicKey string
@@ -272,12 +272,24 @@ func runServer() {
 	})

 	mux.HandleFunc("GET /docs", func(w http.ResponseWriter, _ *http.Request) {
+		// /docs needs to execute the Scalar bundle, so loosen the strict CSP set
+		// by secHeaders for this one page: allow scripts/styles from the jsdelivr
+		// CDN plus inline (Scalar uses inline <script> + inline styles). The CDN
+		// host is the supply-chain trust boundary; pinning a version + SRI here
+		// is the follow-up (M5 partial).
+		w.Header().Set("Content-Security-Policy",
+			"default-src 'self'; "+
+				"script-src 'self' 'unsafe-inline' https://cdn.jsdelivr.net; "+
+				"style-src 'self' 'unsafe-inline' https://cdn.jsdelivr.net; "+
+				"img-src 'self' data: https:; "+
+				"connect-src 'self'; "+
+				"font-src 'self' data: https://cdn.jsdelivr.net")
 		w.Header().Set("Content-Type", "text/html")
 		w.Write([]byte(`<!doctype html><html><head><title>API</title>
 <meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
 <link rel="icon" type="image/svg+xml" href="/favicon.svg"></head>
 <body><script id="api-reference" data-url="/openapi.json" data-configuration='{"layout":"classic"}'></script>
-<script src="https://cdn.jsdelivr.net/npm/@scalar/api-reference"></script></body></html>`))
+<script src="https://cdn.jsdelivr.net/npm/@scalar/api-reference" crossorigin="anonymous"></script></body></html>`))
 	})

 	addr := cfg.Server.Hostname + ":" + cfg.Server.Port
@@ -286,7 +298,7 @@ func runServer() {
 		Addr: addr,
 		// WithClientIP records the source IP for the login throttle (H1); behind a
 		// trusted proxy it reads X-Forwarded-For instead of the proxy's address.
-		Handler:           auth.WithClientIP(cfg.Server.TrustProxy, mux),
+		Handler:           secHeaders(auth.WithClientIP(cfg.Server.TrustProxy, mux)),
 		ReadHeaderTimeout: 10 * time.Second,
 		ReadTimeout:       30 * time.Second,
 		WriteTimeout:      0, // unset: SSE endpoints stream indefinitely
@@ -343,6 +355,27 @@ func runServer() {
 	}
 }

+// secHeaders sets defensive response headers on every HTTP response. The
+// default Content-Security-Policy denies everything (`default-src 'none'`) —
+// correct for the JSON API and the tiny landing/favicon endpoints. /docs
+// overrides it with a CDN-permissive policy because the Scalar bundle needs
+// to execute.
+//
+// HSTS is set unconditionally: nadir always serves TLS directly or sits behind
+// a TLS-terminating proxy (config rejects any other shape), so a browser
+// receiving this header is on an HTTPS connection.
+func secHeaders(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		h := w.Header()
+		h.Set("X-Content-Type-Options", "nosniff")
+		h.Set("X-Frame-Options", "DENY")
+		h.Set("Referrer-Policy", "no-referrer")
+		h.Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
+		h.Set("Content-Security-Policy", "default-src 'none'; frame-ancestors 'none'")
+		next.ServeHTTP(w, r)
+	})
+}
+
 func ensureRoot() {
 	if os.Getuid() != 0 {
 		fatalIf(fmt.Errorf("nadir must run as root"))
@@ -1,6 +1,8 @@
 package main

 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"flag"
 	"fmt"
@@ -15,10 +17,13 @@ import (

 	"nadir"
 	"nadir/internal/config"
+
+	"github.com/jedisct1/go-minisign"
 )

 // updateCmd implements `nadir update`: hit the configured Gitea repo's
-// releases/latest, pick the asset for the host's GOARCH, atomically replace
+// releases/latest, pick the asset for the host's GOARCH, verify the release
+// signature (minisign) and checksum (SHA-256), atomically replace
 // /usr/local/bin/nadir (or wherever the running binary lives), and restart
 // the systemd unit so the new code takes effect.
 func updateCmd(args []string) error {
@@ -66,16 +71,25 @@ func updateCmd(args []string) error {
 		return nil
 	}

+	// Locate the binary asset and the two verification assets in the release.
 	var assetURL, assetName string
+	var sumsURL, sigURL string
 	for _, a := range rel.Assets {
-		if strings.HasSuffix(a.Name, suffix) {
+		switch {
+		case strings.HasSuffix(a.Name, suffix):
 			assetURL, assetName = a.URL, a.Name
-			break
+		case a.Name == "sha256sums.txt":
+			sumsURL = a.URL
+		case a.Name == "sha256sums.txt.minisig":
+			sigURL = a.URL
 		}
 	}
 	if assetURL == "" {
 		return fmt.Errorf("no %s asset in release %s", suffix, rel.TagName)
 	}
+	if sumsURL == "" || sigURL == "" {
+		return fmt.Errorf("release %s is missing sha256sums.txt or sha256sums.txt.minisig — cannot verify; refusing to install an unverified binary", rel.TagName)
+	}

 	exe, err := os.Executable()
 	if err != nil {
@@ -88,6 +102,15 @@ func updateCmd(args []string) error {
 		os.Remove(tmp)
 		return err
 	}
+
+	// Verify: download checksums + signature, check minisign, check SHA-256.
+	fmt.Println("verifying release signature ...")
+	if err := verifyRelease(tmp, assetName, sumsURL, sigURL); err != nil {
+		os.Remove(tmp)
+		return fmt.Errorf("verification failed: %w", err)
+	}
+	fmt.Println("signature and checksum OK.")
+
 	// Atomic on the same filesystem; replaces the on-disk file without
 	// disturbing the still-running process (its inode stays alive).
 	if err := os.Rename(tmp, exe); err != nil {
@@ -103,6 +126,113 @@ func updateCmd(args []string) error {
 	return nil
 }

+// verifyRelease downloads sha256sums.txt + its minisig from the release,
+// verifies the signature against the embedded public key, then checks the
+// downloaded binary's SHA-256 against the matching line in the checksums file.
+func verifyRelease(binaryPath, assetName, sumsURL, sigURL string) error {
+	// Parse the embedded public key. The placeholder file will fail here
+	// (no valid base64 line), which is the desired behavior: updates are
+	// disabled until a real key is committed.
+	pubKey, err := minisign.DecodePublicKey(nadir.ReleasePublicKey)
+	if err != nil {
+		return fmt.Errorf("embedded minisign public key is invalid (is minisign.pub still the placeholder?): %w", err)
+	}
+
+	// Download the checksums file and its signature.
+	sumsBody, err := downloadBytes(sumsURL)
+	if err != nil {
+		return fmt.Errorf("download sha256sums.txt: %w", err)
+	}
+	sigBody, err := downloadBytes(sigURL)
+	if err != nil {
+		return fmt.Errorf("download sha256sums.txt.minisig: %w", err)
+	}
+
+	// Verify the minisign signature on the checksums file.
+	sig, err := minisign.DecodeSignature(string(sigBody))
+	if err != nil {
+		return fmt.Errorf("decode minisig: %w", err)
+	}
+	ok, err := pubKey.Verify(sumsBody, sig)
+	if err != nil {
+		return fmt.Errorf("minisign verify: %w", err)
+	}
+	if !ok {
+		return fmt.Errorf("minisign signature is not valid for this sha256sums.txt")
+	}
+
+	// Find the expected hash for our binary in the signed checksums file.
+	expectedHash, err := findChecksum(string(sumsBody), assetName)
+	if err != nil {
+		return err
+	}
+
+	// Hash the downloaded binary and compare.
+	actualHash, err := sha256File(binaryPath)
+	if err != nil {
+		return fmt.Errorf("hash downloaded binary: %w", err)
+	}
+	if actualHash != expectedHash {
+		return fmt.Errorf("SHA-256 mismatch for %s: expected %s, got %s", assetName, expectedHash, actualHash)
+	}
+	return nil
+}
+
+// findChecksum parses a sha256sums.txt body (one "hash  filename\n" per line)
+// and returns the hex hash for the named asset.
+func findChecksum(sums, assetName string) (string, error) {
+	for _, line := range strings.Split(sums, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		// Standard sha256sum output: "<hex>  <filename>" (two spaces).
+		parts := strings.SplitN(line, "  ", 2)
+		if len(parts) != 2 {
+			// Also accept single-space separation.
+			parts = strings.SplitN(line, " ", 2)
+		}
+		if len(parts) == 2 && strings.TrimSpace(parts[1]) == assetName {
+			h := strings.TrimSpace(parts[0])
+			if len(h) != 64 {
+				return "", fmt.Errorf("sha256sums.txt: invalid hash length for %s: %q", assetName, h)
+			}
+			return strings.ToLower(h), nil
+		}
+	}
+	return "", fmt.Errorf("sha256sums.txt does not contain a hash for %s", assetName)
+}
+
+// sha256File returns the lowercase hex SHA-256 of the file at path.
+func sha256File(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	h := sha256.New()
+	if _, err := io.Copy(h, f); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+// downloadBytes fetches a URL and returns its body as a byte slice (for small
+// files like sha256sums.txt and .minisig).
+func downloadBytes(srcURL string) ([]byte, error) {
+	c := &http.Client{Timeout: 30 * time.Second}
+	resp, err := c.Get(srcURL)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET %s: %s", srcURL, resp.Status)
+	}
+	// Cap read to 1 MB — sha256sums.txt and .minisig are tiny.
+	return io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+}
+
 type giteaRelease struct {
 	TagName string `json:"tag_name"`
 	Assets  []struct {
@@ -136,6 +266,9 @@ func releaseAPIURL(repoURL string) (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("release_repo: %w", err)
 	}
+	if u.Scheme != "https" {
+		return "", fmt.Errorf("release_repo must use https:// (got %q) — auto-update downloads and executes the binary, plaintext would let any on-path attacker replace it", repoURL)
+	}
 	parts := strings.Split(strings.Trim(u.Path, "/"), "/")
 	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
 		return "", fmt.Errorf("release_repo must look like https://host/owner/repo, got %q", repoURL)
@@ -7,19 +7,21 @@ require github.com/msteinert/pam v1.2.0
 require github.com/danielgtaylor/huma/v2 v2.38.0

 require (
-	gopkg.in/yaml.v3 v3.0.1
-	modernc.org/sqlite v1.52.0
 	github.com/coder/websocket v1.8.15
 	github.com/creack/pty v1.1.24
+	gopkg.in/yaml.v3 v3.0.1
+	modernc.org/sqlite v1.52.0
 )

 require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/jedisct1/go-minisign v0.0.0-20260527172527-a09352b57a22 // indirect
 	github.com/mattn/go-isatty v0.0.21 // indirect
 	github.com/ncruces/go-strftime v1.0.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
-	golang.org/x/sys v0.43.0 // indirect
+	golang.org/x/crypto v0.52.0 // indirect
+	golang.org/x/sys v0.45.0 // indirect
 	modernc.org/libc v1.72.3 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect
@@ -16,6 +16,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
 github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
+github.com/jedisct1/go-minisign v0.0.0-20260527172527-a09352b57a22 h1:C68TAi+k12EKJCAmsdaERzQ22ZxVE6n+CuB3kOkhQ7c=
+github.com/jedisct1/go-minisign v0.0.0-20260527172527-a09352b57a22/go.mod h1:vYVVh81Lqe/TP0sPLjiNYcX9Hxy/YSfkUx96lYJeyKo=
 github.com/mattn/go-isatty v0.0.21 h1:xYae+lCNBP7QuW4PUnNG61ffM4hVIfm+zUzDuSzYLGs=
 github.com/mattn/go-isatty v0.0.21/go.mod h1:ZXfXG4SQHsB/w3ZeOYbR0PrPwLy+n6xiMrJlRFqopa4=
 github.com/msteinert/pam v1.2.0 h1:mYfjlvN2KYs2Pb9G6nb/1f/nPfAttT/Jee5Sq9r3bGE=
@@ -30,12 +32,16 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
+golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
+golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
 golang.org/x/mod v0.33.0 h1:tHFzIWbBifEmbwtGz65eaWyGiGZatSrT9prnU8DbVL8=
 golang.org/x/mod v0.33.0/go.mod h1:swjeQEj+6r7fODbD2cqrnje9PnziFuw4bmLbBZFrQ5w=
 golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
 golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
 golang.org/x/sys v0.43.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
+golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.6.0 h1:clScbb1cHjoCkyRbWwBEUZ5H/tIFu5TAXIqaZD0Gcjw=
 golang.org/x/term v0.6.0/go.mod h1:m6U89DPEgQRMq3DNkDClhWw02AUbt2daBVO4cn4Hv9U=
 golang.org/x/tools v0.42.0 h1:uNgphsn75Tdz5Ji2q36v/nsFSfR/9BRFvqhGBaJGd5k=
@@ -60,6 +60,40 @@ do_install() {

  echo "downloading $asset_url ..."
  curl -f --progress-bar -L "$asset_url" -o /usr/local/bin/nadir.tmp
+
+  asset_name=$(basename "$asset_url")
+
+  # Verify SHA-256: download the checksums file published alongside the binary
+  # and confirm the hash matches. This catches CDN corruption and (together with
+  # the HTTPS transport) makes tampered binaries detectable.
+  sums_url="$host/api/v1/repos/$path/releases/latest"
+  sums_asset_url=$(curl -fsSL "$sums_url" \
+    | grep -o '"browser_download_url":"[^"]*sha256sums\.txt"' \
+    | head -n1 \
+    | cut -d'"' -f4)
+
+  if [ -n "$sums_asset_url" ]; then
+    echo "verifying checksum ..."
+    curl -fsSL "$sums_asset_url" -o /tmp/nadir-sha256sums.txt
+    # Extract the expected hash for our asset and compare.
+    expected=$(grep "$asset_name" /tmp/nadir-sha256sums.txt | awk '{print $1}')
+    actual=$(sha256sum /usr/local/bin/nadir.tmp | awk '{print $1}')
+    rm -f /tmp/nadir-sha256sums.txt
+    if [ -z "$expected" ]; then
+      echo "warning: sha256sums.txt does not contain a hash for $asset_name" >&2
+      echo "proceeding without verification" >&2
+    elif [ "$expected" != "$actual" ]; then
+      echo "SHA-256 MISMATCH: expected $expected, got $actual" >&2
+      echo "the downloaded binary may be corrupted or tampered with — aborting" >&2
+      rm -f /usr/local/bin/nadir.tmp
+      exit 1
+    else
+      echo "checksum OK ($actual)"
+    fi
+  else
+    echo "warning: no sha256sums.txt in release — skipping verification" >&2
+  fi
+
  mv /usr/local/bin/nadir.tmp /usr/local/bin/nadir
  chmod +x /usr/local/bin/nadir

@@ -3,6 +3,7 @@ package auth
 import (
 	"context"
 	"net/http"
+	"regexp"
 	"time"

 	"nadir/internal/auditlog"
@@ -10,6 +11,11 @@ import (
 	"github.com/danielgtaylor/huma/v2"
 )

+// loginNameRe is the useradd default NAME_REGEX. Validating at this trust
+// boundary keeps a flag-like name (e.g. "-c", "--help") from reaching `su` in
+// the terminal handler or showing up verbatim in audit logs / throttle keys.
+var loginNameRe = regexp.MustCompile(`^[a-z_][a-z0-9_-]{0,31}\$?$`)
+
 // authenticator verifies a username/password (PAM in production). It's a field
 // of the login handler rather than a package global so tests can inject a stub
 // without mutating shared state.
@@ -53,6 +59,11 @@ func registerLogin(api huma.API, sessions *SessionStore, auditor *auditlog.Store
 		Tags:   []string{"Authentication"},
 		Errors: []int{401, 429},
 	}, func(ctx context.Context, in *LoginInput) (*LoginOutput, error) {
+		// Reject malformed usernames at the trust boundary so PAM, su, and the
+		// audit log never see flag-like or shell-metacharacter input.
+		if !loginNameRe.MatchString(in.Body.Username) {
+			return nil, huma.Error401Unauthorized("invalid credentials")
+		}
 		// Throttle brute force: too many recent failures for this account/source
 		// put it in a short cooldown before the password is even checked.
 		throttleKey := in.Body.Username + "|" + ClientIP(ctx)
@@ -2,6 +2,7 @@ package config

 import (
 	"fmt"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -108,6 +109,15 @@ func Load(path string) (*File, error) {
 	if err := yaml.Unmarshal(data, &f); err != nil {
 		return nil, fmt.Errorf("parse config %s: %w", path, err)
 	}
+	// release_repo, when set, is downloaded over the wire and (for /api/update)
+	// executed. Reject http:// at the boundary so /install.sh and the updater
+	// never have to re-check.
+	if f.Server.ReleaseRepo != "" {
+		u, err := url.Parse(f.Server.ReleaseRepo)
+		if err != nil || u.Scheme != "https" {
+			return nil, fmt.Errorf("server.release_repo must use https:// (got %q)", f.Server.ReleaseRepo)
+		}
+	}
 	return &f, nil
 }

@@ -2,6 +2,7 @@ package system

 import (
 	"context"
+	"regexp"
 	"strings"

 	"nadir/internal/oscmd"
@@ -9,6 +10,11 @@ import (
 	"github.com/danielgtaylor/huma/v2"
 )

+// hostnameRe matches RFC-1123 labels joined by dots, max 253 chars total. Anchored
+// so a leading "-" can't be read as a hostnamectl flag and shell metacharacters
+// can't survive — same pattern the other modules use (CLAUDE.md §5).
+var hostnameRe = regexp.MustCompile(`^[a-zA-Z0-9]([a-zA-Z0-9-]{0,62})(\.[a-zA-Z0-9]([a-zA-Z0-9-]{0,62}))*$`)
+
 type HostnameBody struct {
 	Hostname string `json:"hostname" example:"server01" doc:"System hostname"`
 }
@@ -49,7 +55,10 @@ func registerHostname(api huma.API) {
 		if name == "" {
 			return nil, huma.Error400BadRequest("empty hostname")
 		}
-		if _, err := oscmd.Run("hostnamectl", "set-hostname", name); err != nil {
+		if len(name) > 253 || !hostnameRe.MatchString(name) {
+			return nil, huma.Error400BadRequest("invalid hostname: " + name)
+		}
+		if _, err := oscmd.Run("hostnamectl", "set-hostname", "--", name); err != nil {
 			return nil, huma.Error500InternalServerError("hostnamectl failed", err)
 		}
 		return oscmd.OK(), nil
@@ -5,6 +5,7 @@ import (
 	"math"
 	"net"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strconv"
@@ -161,7 +162,19 @@ func cpuInfo() CPUInfo {
 	// ponytail: cpufreq sysfs is absent on many VMs and stock Ubuntu server
 	// kernels; fall back to /proc/cpuinfo "cpu MHz" — VMs have a fixed clock,
 	// so min == max == cur is the honest answer.
-	if mhz := cpuinfoMaxMHz(string(data)); mhz > 0 {
+	mhz := cpuinfoMaxMHz(string(data))
+	// ponytail: ARM /proc/cpuinfo has no "cpu MHz" and often no "model name";
+	// lscpu decodes the ARM part-id table and reads DMI, so use it as last resort.
+	if c.Model == "" || mhz == 0 {
+		model, lscpuMHz := lscpuFallback()
+		if c.Model == "" {
+			c.Model = model
+		}
+		if mhz == 0 {
+			mhz = lscpuMHz
+		}
+	}
+	if mhz > 0 {
 		if c.CurrentMHz == 0 {
 			c.CurrentMHz = mhz
 		}
@@ -175,6 +188,56 @@ func cpuInfo() CPUInfo {
 	return c
 }

+// lscpuFallback parses `lscpu` for "Model name" and any embedded "@ X.X GHz"
+// or "CPU max MHz:" value. Returns zeros when lscpu is missing or silent.
+func lscpuFallback() (model string, mhz int) {
+	out, err := exec.Command("lscpu").Output()
+	if err != nil {
+		return "", 0
+	}
+	for line := range strings.SplitSeq(string(out), "\n") {
+		k, v, ok := strings.Cut(line, ":")
+		if !ok {
+			continue
+		}
+		k, v = strings.TrimSpace(k), strings.TrimSpace(v)
+		switch k {
+		case "Model name":
+			if model == "" {
+				model = v
+			}
+		case "BIOS Model name":
+			if model == "" {
+				model = v
+			}
+		case "CPU max MHz", "CPU MHz":
+			if f, err := strconv.ParseFloat(v, 64); err == nil && int(f) > mhz {
+				mhz = int(math.Round(f))
+			}
+		}
+	}
+	if mhz == 0 {
+		mhz = parseGHzSuffix(model)
+	}
+	return model, mhz
+}
+
+// parseGHzSuffix pulls "2.0GHz" / "@ 2.0 GHz" out of a model string.
+func parseGHzSuffix(s string) int {
+	i := strings.LastIndex(s, "@")
+	if i < 0 {
+		return 0
+	}
+	rest := strings.TrimSpace(s[i+1:])
+	rest = strings.TrimSuffix(strings.TrimSuffix(rest, "GHz"), "Ghz")
+	rest = strings.TrimSpace(strings.TrimSuffix(rest, "G"))
+	f, err := strconv.ParseFloat(strings.TrimSpace(rest), 64)
+	if err != nil {
+		return 0
+	}
+	return int(math.Round(f * 1000))
+}
+
 // cpuinfoMaxMHz returns the highest "cpu MHz" value across all cores in
 // /proc/cpuinfo, rounded to an int. Returns 0 when no such line exists.
 func cpuinfoMaxMHz(cpuinfo string) int {
@@ -46,7 +46,7 @@ func TestSystemHandlers(t *testing.T) {
 		if reflect.DeepEqual(args, []string{"hostname"}) {
 			return oscmd.MockCommand{Stdout: "server01\n", ExitCode: 0}
 		}
-		if reflect.DeepEqual(args, []string{"set-hostname", "server02"}) {
+		if reflect.DeepEqual(args, []string{"set-hostname", "--", "server02"}) {
 			return oscmd.MockCommand{ExitCode: 0}
 		}
 		return oscmd.MockCommand{ExitCode: 1}
@@ -126,7 +126,7 @@ func (m *terminalModule) Register(api huma.API) {

 		// Launch the user's login shell via su.
 		// "su - <username>" ensures we get their actual environment and shell.
-		cmd := exec.CommandContext(req.Context(), "su", "-", sess.Username)
+		cmd := exec.CommandContext(req.Context(), "su", "-", "--", sess.Username)

 		// Start the command with a PTY.
 		ptmx, err := pty.Start(cmd)
@@ -0,0 +1,2 @@
+untrusted comment: minisign public key: 702ABD7F45200669
+RWRpBiBFf70qcEXS0cOS+8tZ1hpoLj9mX0V5OiE8qYIIZsetU8hNA4Ou