Address several security issues (13870b14) · Commits · Personal Projects / bulletin

batch/batch.go

+2 −2

Original line number	Diff line number	Diff line
		@@ -217,13 +217,13 @@ Match User %s
		X11Forwarding no
		AllowTcpForwarding no
		PermitTunnel no
		ForceCommand %s --ssh
		ForceCommand /usr/sbin/nologin
		AuthorizedKeysCommand %s authorized-keys %%u %%t %%k
		AuthorizedKeysCommandUser %s

		--- Then run: sudo systemctl reload sshd ---

		`, os.Getenv("USER"), bulletin, bulletin, os.Getenv("USER"))
		`, os.Getenv("USER"), bulletin, os.Getenv("USER"))
		_, _ = ask.GetLine("Press Enter to continue after configuring sshd...")
		}

key/key.go

+1 −1

Original line number	Diff line number	Diff line
		@@ -20,7 +20,7 @@ import (
		"golang.org/x/sys/unix"
		)

		var keytemplate = `command="%s -u %s",no-port-forwarding,no-X11-forwarding,no-agent-forwarding %s`
		var keytemplate = `command="%s --user %s",restrict %s`

		// Add adds an ssh key to the `authorized_keys` file.
		func Add(login, public string) error {

onboard/onboard.go

+22 −19

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@ import (
		"fmt"
		"os"
		"strings"
		"time"

		"git.lyda.ie/pp/bulletin/ask"
		"git.lyda.ie/pp/bulletin/authorized"
		@@ -48,13 +49,16 @@ func Run(fingerprint, pubkeyStr string) int {
		if len(shibboleths) > 0 {
		fmt.Println("Before proceeding, please answer the following questions:")
		fmt.Println()
		for _, s := range shibboleths {
		for i, s := range shibboleths {
		answer, err := ask.GetLine(s.Question + " ")
		if err != nil {
		fmt.Println("Aborted.")
		return 1
		}
		if !strings.EqualFold(strings.TrimSpace(answer), strings.TrimSpace(s.Answer)) {
		// Rate limit: increasing delay on wrong answers.
		delay := time.Duration(i+1) * 2 * time.Second
		time.Sleep(delay)
		fmt.Println("Incorrect answer. Access denied.")
		return 1
		}
		@@ -140,38 +144,37 @@ func createAccount(q *storage.Queries, fingerprint, pubkeyStr string) int {
		func linkAccount(q *storage.Queries, fingerprint, pubkeyStr string) int {
		ctx := storage.Context()

		login, err := ask.GetLine("Enter your existing login: ")
		code, err := ask.GetLine("Enter your link code (from SSH LINK command): ")
		if err != nil {
		fmt.Println("Aborted.")
		return 1
		}
		login = strings.ToUpper(strings.TrimSpace(login))

		// Check user exists.
		existing, err := q.GetUser(ctx, login)
		if err != nil \|\| existing.Login == "" {
		fmt.Println("ERROR: User not found.")
		code = strings.TrimSpace(code)
		if code == "" {
		fmt.Println("ERROR: No link code provided.")
		return 1
		}

		// Simple verification: ask for user's name.
		name, err := ask.GetLine("Enter the name on the account to verify: ")
		if err != nil {
		fmt.Println("Aborted.")
		return 1
		}
		if !strings.EqualFold(strings.TrimSpace(name), strings.TrimSpace(existing.Name)) {
		fmt.Println("ERROR: Name does not match. Access denied.")
		// Clean up expired codes first.
		_ = q.DeleteExpiredLinkCodes(ctx)

		// Look up the link code.
		linkCode, err := q.GetLinkCode(ctx, code)
		if err != nil \|\| linkCode.Code == "" {
		fmt.Println("ERROR: Invalid or expired link code.")
		return 1
		}

		// Store the SSH key.
		if err := storeKey(q, fingerprint, pubkeyStr, login); err != nil {
		// Delete the code so it can't be reused.
		_ = q.DeleteLinkCode(ctx, code)

		// Store the SSH key for the linked account.
		if err := storeKey(q, fingerprint, pubkeyStr, linkCode.Login); err != nil {
		fmt.Printf("ERROR: Failed to store SSH key: %s\n", err)
		return 1
		}

		fmt.Printf("Key linked to account %s. Reconnect to start using BULLETIN.\n", login)
		fmt.Printf("Key linked to account %s. Reconnect to start using BULLETIN.\n", linkCode.Login)
		return 0
		}

pager/pager.go

+20 −0

Original line number	Diff line number	Diff line
		@@ -34,8 +34,28 @@ func readKey() (byte, error) {
		return buf[0], nil
		}

		// SanitizeText removes terminal escape sequences and dangerous control
		// characters from text, while preserving UTF-8 and normal whitespace.
		func SanitizeText(s string) string {
		var b strings.Builder
		b.Grow(len(s))
		for _, r := range s {
		// Block ESC and other C0/C1 control characters except safe whitespace.
		if r == '\t' \|\| r == '\n' \|\| r == '\r' {
		b.WriteRune(r)
		continue
		}
		if r < 0x20 \|\| (r >= 0x7f && r <= 0x9f) {
		continue
		}
		b.WriteRune(r)
		}
		return b.String()
		}

		// Pager pages through a string.
		func Pager(content string) bool {
		content = SanitizeText(content)
		lines := strings.Split(content, "\n")
		totalLines := len(lines)

repl/accounts.go

+29 −0

Original line number	Diff line number	Diff line
		package repl

		import (
		"crypto/rand"
		"encoding/hex"
		"errors"
		"fmt"
		"strings"
		@@ -369,6 +371,33 @@ func ActionSSHDelete(cmd *dclish.Command) error {
		return nil
		}

		// ActionSSHLink handles the `SSH LINK` command. It generates a random
		// link code that can be used during onboarding to link a new SSH key
		// to the current user's account.
		func ActionSSHLink(_ *dclish.Command) error {
		ctx := storage.Context()

		// Clean up expired codes first.
		_ = this.Q.DeleteExpiredLinkCodes(ctx)

		// Generate a random code.
		b := make([]byte, 10)
		if _, err := rand.Read(b); err != nil {
		return fmt.Errorf("failed to generate link code: %w", err)
		}
		code := hex.EncodeToString(b)

		// Store it.
		if err := this.Q.CreateLinkCode(ctx, code, this.User.Login); err != nil {
		return fmt.Errorf("failed to create link code: %w", err)
		}

		fmt.Printf("Your link code is: %s\n", code)
		fmt.Println("Use this code during onboarding to link a new SSH key to your account.")
		fmt.Println("This code expires in 15 minutes.")
		return nil
		}

		// ActionSSHFetch handles the `SSH FETCH` command. This command pulls
		// public keys from code sites. It's the quickest way to
		// add a number of keys for a user. An admin can do this