Files
pmg/internal/ui/sandbox_violation.go
Sahil BansalandGitHub 47dd859756 feat(sandbox): report landlock seccomp denials via pmg sandbox violations (#389)
* feat(sandbox): report landlock seccomp denials via pmg sandbox violations

The landlock driver's seccomp supervisor already emitted structured deny
events over the audit socket, but the driver drained them to io.Discard, so
the violation cache was never populated on Linux and violations list /
explain always came up empty.

Capture the events at the driver, enrich them with access mode and process
name, and implement BestEffortViolation mirroring the seatbelt reporter:
failure-only collection, seccomp_deny events only, (kind, target) dedupe.
The platform-neutral cache/list/explain pipeline picks it up unchanged.

Only the seccomp deny-list layer is observable; denials made by the
Landlock LSM itself (allow-list boundary, delete/rename, network) fail
in-kernel with no userspace signal and are documented as out of scope.

Also make the explain renderer driver-neutral: the raw-log label was
hardcoded as "Seatbelt log" and an empty correlation ID printed a blank
value.

* fix: address review findings on landlock violation reporting

Report the deny rule that fired, not the requested access: an O_RDWR open
denied by a read-only rule now surfaces as a read denial with an effective
override suggestion (allow write= prunes only deny_write). The matched rule
path is emitted as rule_path and mapped to RuleTarget, bringing the
"Matched rule:" line to parity with seatbelt.

Dedupe deny events by (kind, path) at capture time so a retry loop on one
denied path cannot fill the buffer and evict a later distinct denial; the
cap now bounds distinct denials.

Stamp deny events with a timestamp (they rendered "ts":0 in the raw log)
and default unknown syscalls to generic_deny instead of fs_write.

* refactor: single source for the deny dedupe key

Capture-time and extract-time dedupe must agree on what identifies a
denial; building the key in two places risks them drifting apart.

* fix: bound the capture dedupe map by marking keys only on append

seen grew for every distinct deny key even after the buffer was full,
and keys carry attacker-chosen path bytes — a hostile process looping
over crafted unique denied paths could grow the pmg parent's memory for
the run's duration, defeating the cap. Marking keys only when the event
is appended bounds the map at the cap and keeps the one-time drop
warning reachable for distinct denials past it.

* docs(sandbox): AppArmor userns fix for the Landlock driver on Ubuntu 23.10+

The shim fails with "install seccomp: ... permission denied" when
kernel.apparmor_restrict_unprivileged_userns=1. Document the per-binary
AppArmor profile as the recommended fix and the sysctl as the blunt
alternative.

* docs(sandbox): drop em dashes from the landlock sections

* fix(doctor): cover landlock in the AppArmor userns probe

The warn detail only named the bwrap failure and the only suggested fix
was the system-wide sysctl. Name the landlock shim error too and suggest
the per-binary AppArmor profile first, pointing at the new docs section.
2026-07-25 12:38:27 +00:00

200 lines
5.7 KiB
Go

package ui
import (
"fmt"
"io"
"strings"
"time"
pmgsandbox "github.com/safedep/pmg/sandbox"
)
// FormatSandboxOverrideFlag renders an OverrideSuggestion as a `--sandbox-allow`
// CLI flag invocation. Returns "" when there is nothing safe to suggest.
//
// The flag name lives here (not in sandbox/) because it is CLI-surface owned
// by the cmd layer; the sandbox package only knows kind + target.
func FormatSandboxOverrideFlag(o *pmgsandbox.OverrideSuggestion) string {
if o == nil {
return ""
}
quoted := shellQuote(o.Target)
switch o.Kind {
case pmgsandbox.ViolationKindFSRead:
return "--sandbox-allow read=" + quoted
case pmgsandbox.ViolationKindFSWrite, pmgsandbox.ViolationKindFSDeleteOrRename:
return "--sandbox-allow write=" + quoted
case pmgsandbox.ViolationKindExec:
return "--sandbox-allow exec=" + quoted
default:
return ""
}
}
// FormatSandboxHint produces the short, one-line "Reason: ... Override: ..."
// summary shown above the detail block.
func FormatSandboxHint(primary *pmgsandbox.Violation, override *pmgsandbox.OverrideSuggestion) string {
if primary == nil {
return "Reason: sandbox denied an operation"
}
hint := "Reason: " + primary.RuleLabel
if flag := FormatSandboxOverrideFlag(override); flag != "" {
hint += ". Override: " + flag
}
return hint
}
// FormatSandboxDetails produces the multi-line detail block shown beneath the
// hint. Each line is "Label: value"; callers indent as they see fit.
func FormatSandboxDetails(report *pmgsandbox.ViolationReport, primary *pmgsandbox.Violation) string {
if primary == nil || report == nil {
return ""
}
process := primary.Process
if process == "" {
process = "unknown"
}
lines := []string{
"Sandbox: " + string(report.SandboxName),
"Policy: " + report.PolicyName,
}
if report.CorrelationID != "" {
lines = append(lines, "Correlation: "+report.CorrelationID)
}
lines = append(lines,
"Process: "+process,
"Violation: "+primary.RuleLabel,
)
if primary.RuleTarget != "" && primary.RuleTarget != primary.Target {
lines = append(lines, "Matched rule: "+primary.RuleTarget)
}
if primary.RawLog != "" {
lines = append(lines, "Raw log: "+primary.RawLog)
}
if len(report.Violations) > 1 {
lines = append(lines, fmt.Sprintf("Additional denials observed: %d", len(report.Violations)-1))
}
return strings.Join(lines, "\n")
}
// RenderSandboxViolation writes the full human-readable explanation for a
// cached violation record to out. cmd handlers should prefer this over
// re-implementing the layout — it owns the section ordering, colors, and
// separator conventions.
func RenderSandboxViolation(out io.Writer, rec *pmgsandbox.ViolationCacheRecord) error {
if rec == nil || rec.Report == nil {
return fmt.Errorf("render sandbox violation: empty record")
}
exp := pmgsandbox.BuildExplanation(rec.Report)
recordedAt := ""
if !rec.RecordedAt.IsZero() {
recordedAt = rec.RecordedAt.UTC().Format(time.RFC3339)
}
header := fmt.Sprintf("%s %s %s %s",
Colors.Dim("Sandbox:"), Colors.Bold(string(rec.Report.SandboxName)),
Colors.Dim("Profile:"), Colors.Bold(rec.Report.PolicyName),
)
if recordedAt != "" {
header = fmt.Sprintf("%s %s %s", header, Colors.Dim("Recorded:"), Colors.Normal(recordedAt))
}
if _, err := fmt.Fprintln(out, header); err != nil {
return err
}
if _, err := fmt.Fprintln(out, Colors.Normal("--------------------------------------------------------")); err != nil {
return err
}
if _, err := fmt.Fprintln(out); err != nil {
return err
}
hint := FormatSandboxHint(exp.Primary, exp.Override)
if hint != "" {
if _, err := fmt.Fprintln(out, hint); err != nil {
return err
}
if _, err := fmt.Fprintln(out); err != nil {
return err
}
}
details := FormatSandboxDetails(rec.Report, exp.Primary)
if details != "" {
if _, err := fmt.Fprintln(out, Colors.Bold("Details:")); err != nil {
return err
}
for _, line := range strings.Split(details, "\n") {
if _, err := fmt.Fprintf(out, " %s\n", line); err != nil {
return err
}
}
if _, err := fmt.Fprintln(out); err != nil {
return err
}
}
if flag := FormatSandboxOverrideFlag(exp.Override); flag != "" {
if _, err := fmt.Fprintln(out, Colors.Bold("Suggested override:")); err != nil {
return err
}
if _, err := fmt.Fprintf(out, " %s\n", Colors.Cyan(flag)); err != nil {
return err
}
if _, err := fmt.Fprintln(out); err != nil {
return err
}
// `pmg sandbox allow` refuses sensitive targets without --force, so
// do not suggest a command that would immediately fail.
if !pmgsandbox.IsSensitiveProjectTarget(exp.Override.Target) {
if _, err := fmt.Fprintln(out, Colors.Dim("Remember for this project: pmg sandbox allow --last --all")); err != nil {
return err
}
if _, err := fmt.Fprintln(out); err != nil {
return err
}
}
}
if exp.Primary != nil {
if _, err := fmt.Fprintln(out, Colors.Bold("Primary violation:")); err != nil {
return err
}
if _, err := fmt.Fprintf(out, " %s %s\n", Colors.Dim("Kind:"), string(exp.Primary.Kind)); err != nil {
return err
}
if _, err := fmt.Fprintf(out, " %s %s\n", Colors.Dim("Target:"), exp.Primary.Target); err != nil {
return err
}
if _, err := fmt.Fprintf(out, " %s %s\n", Colors.Dim("Rule:"), exp.Primary.RuleLabel); err != nil {
return err
}
if exp.Primary.Process != "" {
if _, err := fmt.Fprintf(out, " %s %s\n", Colors.Dim("Process:"), exp.Primary.Process); err != nil {
return err
}
}
}
return nil
}
// shellQuote wraps value in single quotes, escaping any embedded single
// quotes. Used so suggested override flags can be copy-pasted into a POSIX
// shell verbatim regardless of spaces or quotes in the target.
func shellQuote(value string) string {
return "'" + strings.ReplaceAll(value, "'", `'\''`) + "'"
}