Monorepo for Tangled
guard: add secure-mode sandboxing for SSH git operations
authored by
Anirudh Oppiliappan
and committed by
Tangled
(Jun 12, 2026, 12:22 PM +0300)
b33f1326
388e28a4
+28
+28
guard/guard.go
+28
guard/guard.go
···
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11
"os"
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"os/exec"
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"strings"
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+
"syscall"
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securejoin "github.com/cyphar/filepath-securejoin"
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"github.com/urfave/cli/v3"
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+
"tangled.org/core/knotserver/sandbox"
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"tangled.org/core/log"
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)
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···
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Usage: "path to message of the day file",
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Value: "/home/git/motd",
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},
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&cli.BoolFlag{
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Name: "secure-mode",
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Usage: "isolate git subprocesses to their own repository directory",
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},
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},
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}
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}
···
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logPath := cmd.String("log-path")
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endpoint := cmd.String("internal-api")
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motdFile := cmd.String("motd-file")
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secureMode := cmd.Bool("secure-mode")
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logFile, err := os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
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if err != nil {
···
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gitCmd.Env = append(os.Environ(),
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fmt.Sprintf("GIT_USER_DID=%s", incomingUser),
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)
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+
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if secureMode {
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sb, warn := sandbox.New(func(repoPath string) (uint32, uint32, error) {
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return sandbox.LookupUIDForRepoPath(gitDir, repoPath)
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})
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if warn != "" {
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l.Warn("secure-mode: sandbox degraded", "reason", warn)
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} else {
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l.Info("secure-mode: wrapping git command", "backend", sb.Name())
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}
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wrapped, wrapErr := sb.Wrap(fullPath, gitCmd)
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if wrapErr != nil {
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l.Error("sandbox wrap failed", "error", wrapErr)
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} else {
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gitCmd = wrapped
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}
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}
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+
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if gitCmd.SysProcAttr == nil {
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gitCmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
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}
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if err := gitCmd.Run(); err != nil {
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l.Error("command failed", "error", err)