feat(track-c-mvp): C3 data-exfil guard + C6 sandbox scaffold + Phase 2 suite
C3 (V19) data-exfil-guard.sh: destination-aware egress checkpoint built on the H4 detectors. cloud/artifact boundaries fail closed on any secret; audit boundary emits a PII-masked copy (fail closed on an unmaskable secret). Covers secret-to-cloud, artifact-leaks-env, and PII-in-audit. C6 (V22) sandbox-run.sh: static policy pre-check (BLOCK on reading ~/.ssh/creds, network egress, fork bomb, writes outside workspace, huge-file/disk-fill) plus ulimit file-size/CPU backstops and the wall-clock timeout. HONEST SCOPE: this is not kernel isolation — the production target (docker --network=none --read-only --pids-limit / nsjail) is documented as TODO(C6-prod). Process cap is opt-in so it never breaks legitimate commands on a busy host. phase2-track-c-tests.sh: 29 adversarial checks (C1 13, C2 6, C3 4, C6 6). Baselines preserved: run-casan4 35/35, adversarial 44/44. Running total: 35 + 44 + 25 + 29 = 133 checks. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
thanhnv
co-authored by
Claude Opus 4.8
Claude Opus 4.8
parent
c51e0f88a3
commit
dbeb8e89d2
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#!/usr/bin/env bash
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set -uo pipefail
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# CASAN Track C-MVP — Data-exfiltration guard (C3, V19).
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#
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# Content leaving the trusted boundary must not carry secrets/PII. This guard
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# is the checkpoint for three egress destinations, each with its own policy:
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#
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# cloud — content about to be sent to a CLOUD model (OpenAI/Anthropic).
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# A secret => BLOCK (fail closed); PII => masked copy emitted.
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# Critical once Plan-03 wires a real cloud backend.
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# audit — content about to be written to an audit/log record.
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# PII/secret => masked copy emitted (BLOCK if masking impossible).
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# artifact — a generated artifact about to be persisted/shared.
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# Any secret / env-token => BLOCK.
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#
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# It reuses security-check.sh's secret/PII detection + masking (single source of
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# truth) and applies the destination policy on top. Deterministic; no model call.
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#
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# Usage: data-exfil-guard.sh <file> <cloud|audit|artifact> [masked-output-file]
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# Exit: 0 allowed (possibly masked), 2 blocked (secret at a fail-closed boundary),
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# 64 usage.
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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# shellcheck source=casan-log.sh
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source "$SCRIPT_DIR/casan-log.sh"
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FILE="${1:-}"
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DEST="${2:-}"
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MASKED_OUT="${3:-}"
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if [[ -z "$FILE" || ! -f "$FILE" || -z "$DEST" ]]; then
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echo "Usage: data-exfil-guard.sh <file> <cloud|audit|artifact> [masked-output-file]" >&2
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exit 64
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fi
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case "$DEST" in cloud|audit|artifact) ;; *) echo "unknown destination: $DEST" >&2; exit 64 ;; esac
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SCAN_OUT="$(mktemp)"
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trap 'rm -f "$SCAN_OUT"' EXIT
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# Deterministic detection: security-check input-mode (semantic OFF). rc==2 means
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# a secret/critical pattern was found; on rc==0 SCAN_OUT holds the PII-masked copy.
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CASAN_SECURITY_STRICT=0 CASAN_SEMANTIC_CLASSIFY=0 \
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bash "$SCRIPT_DIR/security-check.sh" "$FILE" "$SCAN_OUT" input >/dev/null 2>&1
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SC_RC=$?
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if [[ "$SC_RC" -eq 2 ]]; then
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# A secret / private key / connection string / card was detected.
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case "$DEST" in
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cloud)
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casan_log error data-exfil "DATA_EXFIL_BLOCKED destination=cloud reason=secret_would_leave_org"
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echo "DATA_EXFIL_BLOCKED destination=cloud reason=secret_in_content" >&2
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exit 2 ;;
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artifact)
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casan_log error data-exfil "DATA_EXFIL_BLOCKED destination=artifact reason=secret_or_env_token"
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echo "DATA_EXFIL_BLOCKED destination=artifact reason=secret_or_env_token" >&2
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exit 2 ;;
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audit)
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# Audit must never store a raw secret and must never lose the record; if we
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# cannot safely mask a hard secret we fail closed rather than log it raw.
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casan_log error data-exfil "DATA_EXFIL_BLOCKED destination=audit reason=unmaskable_secret"
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echo "DATA_EXFIL_BLOCKED destination=audit reason=unmaskable_secret" >&2
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exit 2 ;;
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esac
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elif [[ "$SC_RC" -ne 0 ]]; then
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echo "DATA_EXFIL_SCAN_ERROR destination=$DEST rc=$SC_RC" >&2
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exit 2 # fail closed on scan error
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fi
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# rc==0: content is safe; SCAN_OUT is the PII-masked copy.
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if [[ -n "$MASKED_OUT" ]]; then
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cp "$SCAN_OUT" "$MASKED_OUT"
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fi
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if ! cmp -s "$FILE" "$SCAN_OUT"; then
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casan_log info data-exfil "DATA_EXFIL_MASKED destination=$DEST (PII redacted before egress)"
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echo "DATA_EXFIL_MASKED destination=$DEST"
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else
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echo "DATA_EXFIL_CLEAN destination=$DEST"
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fi
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exit 0
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+104
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#!/usr/bin/env bash
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set -uo pipefail
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# CASAN Track C-MVP — Runtime sandbox scaffold (C6, V22).
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#
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# Generated code/tests must not read secrets, reach the network, fork-bomb, write
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# outside the workspace, or fill the disk. Full isolation needs a container with
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# namespaces/seccomp/network-off (documented below as the production target).
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# This scaffold provides two enforceable layers WITHOUT root/Docker:
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# 1. Static policy pre-check — refuse to launch a command that matches a known
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# dangerous operation (BLOCK before anything runs). This is the deterministic
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# gate the tests assert on.
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# 2. Runtime rlimits (ulimit) — file-size, CPU, and process caps as a backstop,
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# plus the existing wall-clock timeout (tool-exec.sh).
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#
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# HONEST SCOPE — this is NOT kernel isolation. A determined payload using a
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# syscall the static check doesn't model can still act within the rlimits. The
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# production requirement is: run inside `docker run --network=none --read-only
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# --pids-limit ... --memory ... -v <workspace>:/work:rw`. Do not present this as
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# a full sandbox. See TODO(C6-prod) below.
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#
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# Usage:
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# sandbox-run.sh --workspace <dir> [--max-file-kb N] [--cpu-seconds N]
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# [--max-procs N] [--timeout N] -- <command...>
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# Exit: 2 policy-blocked, 124 timeout, else the command's own exit code.
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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# shellcheck source=casan-log.sh
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source "$SCRIPT_DIR/casan-log.sh"
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WORKSPACE="$PWD"
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MAX_FILE_KB="${CASAN_SANDBOX_MAX_FILE_KB:-51200}" # 50 MB default
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CPU_SECONDS="${CASAN_SANDBOX_CPU_SECONDS:-30}"
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# Process cap is OPT-IN: `ulimit -u` is a per-USER limit, so forcing a low value
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# on a busy host makes legitimate commands fail to fork. The fork-bomb static
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# check is the real gate; a container --pids-limit is the production backstop.
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MAX_PROCS="${CASAN_SANDBOX_MAX_PROCS:-}"
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TIMEOUT="${CASAN_SANDBOX_TIMEOUT:-30}"
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while [[ "$#" -gt 0 ]]; do
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case "$1" in
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--workspace) WORKSPACE="${2:-}"; shift 2 ;;
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--max-file-kb) MAX_FILE_KB="${2:-}"; shift 2 ;;
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--cpu-seconds) CPU_SECONDS="${2:-}"; shift 2 ;;
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--max-procs) MAX_PROCS="${2:-}"; shift 2 ;;
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--timeout) TIMEOUT="${2:-}"; shift 2 ;;
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--) shift; break ;;
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*) echo "sandbox-run.sh: unknown arg $1" >&2; exit 64 ;;
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esac
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done
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if [[ "$#" -eq 0 ]]; then
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echo "Usage: sandbox-run.sh --workspace <dir> -- <command...>" >&2
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exit 64
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fi
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CMD_STR="$*"
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low="$(printf '%s' "$CMD_STR" | tr '[:upper:]' '[:lower:]')"
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# ── 1. Static policy pre-check ──────────────────────────────────────────────
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block() {
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casan_log error sandbox "SANDBOX_BLOCKED reason=$1 cmd=${CMD_STR:0:120}"
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echo "SANDBOX_BLOCKED reason=$1" >&2
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exit 2
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}
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# Read of SSH / credential material.
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printf '%s' "$low" | grep -Eq '(\.ssh/|id_rsa|id_ed25519|authorized_keys|known_hosts|/etc/shadow|/etc/passwd|\.aws/credentials|\.netrc)' \
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&& block "read_sensitive_credentials"
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# Network egress of any kind (sandboxed code should be offline).
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printf '%s' "$low" | grep -Eq '(\bcurl\b|\bwget\b|\bnc\b|\bncat\b|\bscp\b|\bsftp\b|\bssh\b|\btelnet\b|\bftp\b|/dev/tcp/|\bnslookup\b|\bdig\b)' \
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&& block "network_egress"
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# Fork bomb / uncontrolled process spawning.
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printf '%s' "$CMD_STR" | grep -Eq ':\(\)\s*\{\s*:?\s*\|?\s*:?\s*&?\s*\}|\bfork\s*\(\)\s*while|while\s*\(\s*true\s*\)\s*\{\s*fork' \
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&& block "fork_bomb"
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# Huge-file / disk-fill.
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printf '%s' "$low" | grep -Eq '\bdd\b[^\n]*of=|truncate\s+-s\s*[0-9]+\s*[gt]|fallocate\s+-l\s*[0-9]+\s*[gt]|head\s+-c\s*[0-9]+\s*[gt]|\byes\b[^\n]*>' \
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&& block "huge_file_or_disk_fill"
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# Writes outside the workspace: redirection to an absolute path not under $WORKSPACE, or path traversal.
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WS_ABS="$(cd "$WORKSPACE" 2>/dev/null && pwd || echo "$WORKSPACE")"
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while read -r target; do
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[[ -z "$target" ]] && continue
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case "$target" in
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/*) [[ "$target" == "$WS_ABS"* || "$target" == /tmp/* || "$target" == /var/folders/* || "$target" == /dev/null ]] || block "write_outside_workspace:$target" ;;
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*"../"*) block "path_traversal_write:$target" ;;
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esac
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done < <(printf '%s\n' "$CMD_STR" | grep -oE '>>?[[:space:]]*[^[:space:];|&]+' | sed -E 's/^>>?[[:space:]]*//')
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# ── 2. Runtime rlimits + wall-clock timeout ─────────────────────────────────
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casan_log debug sandbox "SANDBOX_RUN workspace=$WS_ABS file_kb=$MAX_FILE_KB cpu=$CPU_SECONDS procs=$MAX_PROCS timeout=$TIMEOUT"
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(
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ulimit -f "$((MAX_FILE_KB * 2))" 2>/dev/null || true # ulimit -f is in 512-byte blocks
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ulimit -t "$CPU_SECONDS" 2>/dev/null || true
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[[ -n "$MAX_PROCS" ]] && { ulimit -u "$MAX_PROCS" 2>/dev/null || true; }
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cd "$WS_ABS" 2>/dev/null || true
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exec "$SCRIPT_DIR/tool-exec.sh" "$TIMEOUT" -- "$@"
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)
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rc=$?
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exit "$rc"
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# TODO(C6-prod): replace the rlimit backstop with true isolation:
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# docker run --rm --network=none --read-only --pids-limit=$MAX_PROCS \
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# --memory=512m --cpus=1 -v "$WORKSPACE":/work:rw -w /work <image> <cmd>
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# and/or bubblewrap/nsjail on Linux CI. Track as a Track-C production task.
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