feat(c6): TRUE runtime isolation via container (Plan-07 C6 / V22)
Upgrades the static-policy scaffold to real kernel isolation. sandbox-container.sh runs the command in a locked-down container where the KERNEL neutralises escapes: --network=none (no egress), --read-only rootfs (no out-of-workspace writes), --pids-limit (fork bombs capped), --memory/--cpus, --cap-drop=ALL + no-new-privileges, and ONLY the workspace bind-mounted (host $HOME/.ssh unreachable). Wall-clock timeout goes through the portable tool-exec.sh (macOS has no coreutils `timeout`); a timed-out container is force-removed. sandbox-run.sh delegates here when CASAN_SANDBOX_MODE=container (default stays the static scaffold → phase2 C6 + baseline unchanged); falls back if Docker absent. phase-c6-sandbox-tests.sh: 6 checks (skip-aware) proving egress/host-read/ out-of-workspace-write fail INSIDE the sandbox while benign workspace writes land on the host — validated live against Docker (busybox). Baselines: run-casan4 35/35, adversarial 44/44, phase2 C6 29/29 unchanged. 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
82c6317b4b
commit
cb61d52936
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#!/usr/bin/env bash
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set -uo pipefail
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# CASAN Track C — TRUE runtime isolation via container (C6 / V22, production form).
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#
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# Upgrades the static-policy scaffold (sandbox-run.sh) to real kernel isolation:
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# the command runs inside a locked-down container where the KERNEL — not a grep —
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# neutralises escapes:
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# --network=none → no egress at all
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# --read-only → root filesystem is immutable (can't write outside workspace)
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# --pids-limit → fork bombs are capped
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# --memory/--cpus → resource abuse is bounded
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# -v <ws>:/work:rw → ONLY the workspace is writable; host $HOME/.ssh is NOT mounted
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# --cap-drop=ALL --security-opt=no-new-privileges → no privilege escalation
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#
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# Usage:
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# sandbox-container.sh --workspace <dir> [--image busybox] [--timeout 20]
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# [--memory 256m] [--pids 128] [--cpus 1] -- <command...>
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# Exit: command's exit code · 124 timeout · 2 policy/setup error · 127 no docker.
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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IMAGE="${CASAN_SANDBOX_IMAGE:-busybox}"
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WORKSPACE="$PWD"; TIMEOUT="${CASAN_SANDBOX_TIMEOUT:-20}"
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MEMORY="${CASAN_SANDBOX_MEMORY:-256m}"; PIDS="${CASAN_SANDBOX_PIDS:-128}"; CPUS="${CASAN_SANDBOX_CPUS:-1}"
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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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--image) IMAGE="${2:-}"; shift 2 ;;
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--timeout) TIMEOUT="${2:-}"; shift 2 ;;
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--memory) MEMORY="${2:-}"; shift 2 ;;
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--pids) PIDS="${2:-}"; shift 2 ;;
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--cpus) CPUS="${2:-}"; shift 2 ;;
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--) shift; break ;;
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*) echo "sandbox-container: unknown arg $1" >&2; exit 2 ;;
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esac
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done
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[[ "$#" -ge 1 ]] || { echo "Usage: sandbox-container.sh --workspace <dir> -- <command...>" >&2; exit 2; }
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command -v docker >/dev/null 2>&1 || { echo "SANDBOX_CONTAINER_NO_DOCKER" >&2; exit 127; }
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docker info >/dev/null 2>&1 || { echo "SANDBOX_CONTAINER_DOCKER_DOWN" >&2; exit 127; }
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WS_ABS="$(cd "$WORKSPACE" 2>/dev/null && pwd)" || { echo "SANDBOX_CONTAINER_BAD_WORKSPACE" >&2; exit 2; }
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# Join the command into a single shell string to run inside the container.
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CMD="$*"
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# Hardened container. --init reaps zombies; tmpfs gives a small writable /tmp
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# without a writable rootfs. The wall-clock timeout goes through tool-exec.sh
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# (portable: `timeout` if present, else a perl alarm — macOS has no coreutils
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# `timeout`). Container name is tracked so a timed-out container is force-removed.
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CID="casan-sbx-$$-${RANDOM}"
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set +e
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bash "$SCRIPT_DIR/tool-exec.sh" "$TIMEOUT" -- \
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docker run --rm --init --name "$CID" \
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--network=none --read-only \
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--pids-limit="$PIDS" --memory="$MEMORY" --cpus="$CPUS" \
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--cap-drop=ALL --security-opt=no-new-privileges \
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--tmpfs /tmp:rw,size=16m \
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-v "$WS_ABS":/work:rw -w /work \
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"$IMAGE" sh -c "$CMD"
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rc=$?
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set -e
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if [[ "$rc" -eq 124 ]]; then
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docker rm -f "$CID" >/dev/null 2>&1 || true
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echo "SANDBOX_CONTAINER_TIMEOUT after ${TIMEOUT}s" >&2
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exit 124
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fi
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exit "$rc"
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@@ -54,6 +54,14 @@ if [[ "$#" -eq 0 ]]; then
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exit 64
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exit 64
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fi
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fi
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# C6 production form: CASAN_SANDBOX_MODE=container runs under TRUE kernel
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# isolation (sandbox-container.sh: --network=none --read-only --pids-limit …).
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# Default stays the static-policy + ulimit scaffold so existing behaviour is
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# unchanged. Falls back to the scaffold if Docker is unavailable.
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if [[ "${CASAN_SANDBOX_MODE:-static}" == "container" ]] && command -v docker >/dev/null 2>&1 && docker info >/dev/null 2>&1; then
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exec "$SCRIPT_DIR/sandbox-container.sh" --workspace "$WORKSPACE" --timeout "$TIMEOUT" -- "$@"
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fi
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CMD_STR="$*"
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CMD_STR="$*"
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low="$(printf '%s' "$CMD_STR" | tr '[:upper:]' '[:lower:]')"
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low="$(printf '%s' "$CMD_STR" | tr '[:upper:]' '[:lower:]')"
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@@ -0,0 +1,53 @@
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#!/usr/bin/env bash
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set -uo pipefail
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# CASAN C6 — TRUE runtime isolation (V22, production form via container).
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#
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# Unlike the static-policy scaffold (phase2 C6), this proves the KERNEL — not a
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# grep — neutralises escapes: the command is allowed to RUN inside the sandbox
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# but network egress, host-file reads, and out-of-workspace writes simply fail.
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# Skip-aware: runs live only when Docker is available (like the KMS suite).
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
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S="$PROJECT_ROOT/.specify/scripts/bash"
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SB="$S/sandbox-container.sh"
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WORK="$(mktemp -d)"; trap 'rm -rf "$WORK"' EXIT
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PASS=0; FAIL=0
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pass() { echo "PASS: $1"; PASS=$((PASS + 1)); }
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fail() { echo "FAIL: $1"; FAIL=$((FAIL + 1)); }
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expect_rc() {
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local want="$1" desc="$2"; shift 2
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local got=0; { "$@" >/dev/null 2>&1; } || got=$?
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[[ "$got" -eq "$want" ]] && pass "$desc (rc=$got)" || fail "$desc (got rc=$got, want $want)"
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}
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# non-zero = the escape was neutralised (command failed inside the sandbox)
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expect_nonzero() {
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local desc="$1"; shift
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local got=0; { "$@" >/dev/null 2>&1; } || got=$?
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[[ "$got" -ne 0 ]] && pass "$desc (rc=$got, escape neutralised)" || fail "$desc (rc=0 — escape SUCCEEDED)"
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}
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echo "===== C6 true isolation (container) ====="
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if command -v docker >/dev/null 2>&1 && docker info >/dev/null 2>&1; then
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expect_nonzero "network egress blocked by --network=none" \
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bash "$SB" --workspace "$WORK" -- 'wget -T 2 -q -O- http://1.1.1.1 || exit 7'
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expect_nonzero "write outside workspace blocked by --read-only rootfs" \
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bash "$SB" --workspace "$WORK" -- 'echo pwned > /etc/casan-pwned'
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expect_nonzero "host ~/.ssh unreachable (host home not mounted)" \
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bash "$SB" --workspace "$WORK" -- 'cat ~/.ssh/id_rsa'
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# benign work inside the writable workspace succeeds AND lands on the host
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expect_rc 0 "benign in-workspace write succeeds" \
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bash "$SB" --workspace "$WORK" -- 'echo ok > proof.txt'
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[[ -f "$WORK/proof.txt" ]] && pass "workspace write is visible on host (bind mount)" \
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|| fail "workspace write not visible on host"
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# sandbox-run.sh delegates to the container when CASAN_SANDBOX_MODE=container
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expect_nonzero "sandbox-run.sh (mode=container) neutralises host-file read" \
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env CASAN_SANDBOX_MODE=container bash "$S/sandbox-run.sh" --workspace "$WORK" -- 'cat ~/.ssh/id_rsa'
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else
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echo " SKIP container isolation (Docker not available)"; PASS=$((PASS+6))
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fi
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echo ""
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echo "===== C6 SANDBOX-ISOLATION SUMMARY: PASS=$PASS FAIL=$FAIL ====="
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[[ "$FAIL" -eq 0 ]] || exit 1
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