fix(security): confine CRI localhostProfile seccomp path to the seccomp root (LOW) - #143
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…mp root LOW. `parse_localhost_seccomp_deny` did `std::fs::read_to_string(localhost_ref)` with no path confinement. `localhost_ref` is the pod's `securityContext.seccompProfile.localhostProfile` — attacker-settable through the CRI by anyone who can create pods — so it was an arbitrary host-file OPEN primitive (a path-traversal / file-existence oracle). Information disclosure is limited (the parse error is only warn-logged, never returned to the gRPC caller, and content only escapes as syscall names from valid OCI-seccomp JSON into the attacker's own container), hence LOW — but the missing guard is real. Fix: `confined_seccomp_path(localhost_ref, root)` rejects any `..` component and requires an absolute ref to lie within the seccomp root; a relative ref resolves under it. The root is injected (default /var/lib/kubelet/seccomp via `seccomp_profile_root()`, override A3S_BOX_SECCOMP_PROFILE_ROOT) so the check is testable without process-global env. An out-of-root/traversing ref is rejected and the caller falls back to RuntimeDefault (never unconfined). Tests: new confines_localhost_profile_to_root_and_rejects_traversal (rejects `../../etc/passwd`, `/etc/passwd`, prefix-confusion, etc.); the two existing parse_localhost_seccomp_deny tests now pass their tempdir as the root. Full a3s-box-cri lib suite (250) green; neuter-verified (disabling the root check makes the new test FAIL on /etc/passwd); fmt + clippy clean. Completes the untrusted-input security audit (4/4): after #141 (CRITICAL digest traversal), #142 (HIGH/MED bombs), #140 (HIGH whiteout deletion).
ZhiXiao-Lin
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Severity: LOW (arbitrary host-file open oracle via CRI)
parse_localhost_seccomp_denyreadlocalhost_refoff the host disk with no path confinement.localhost_refis a pod'ssecurityContext.seccompProfile.localhostProfile— attacker-settable by anyone who can create pods — so it was an arbitrary host-file open primitive (path-traversal / file-existence oracle).Rated LOW (not the HIGH the finder first proposed): information disclosure is refuted — the parse error is only
tracing::warn-logged, never returned to the gRPC caller, and content only escapes as syscall names from valid OCI-seccomp JSON into the attacker's own container. But the missing guard is real.Fix
confined_seccomp_pathmirrors kubelet/containerd semantics:/var/lib/kubelet/seccomp, overrideA3S_BOX_SECCOMP_PROFILE_ROOT),..component,An out-of-root or traversing ref is rejected and the caller falls back to RuntimeDefault (never unconfined).
Test (TDD + neuter-verified)
confines_localhost_profile_to_root_and_rejects_traversal— accepts in-root relative/absolute refs; rejects../../etc/passwd,sub/../../escape,/etc/passwd,/etc/shadow,/var/lib/kubelet/seccomp-evil/x(prefix-confusion). Neuter-verified on the KVM server (disabling the root check makes it FAIL on/etc/passwd); fmt + clippy clean.Completes the untrusted-input security audit (4/4)
After #141 (CRITICAL digest path-traversal), #142 (HIGH/MED decompression bombs), #140 (HIGH whiteout host-file deletion).