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actornet: pin the sysctls a sandbox namespace inherits from the node - #3310
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Eitan Yarmush (EItanya) merged 1 commit intoOct 27, 2026
Merged
Eitan Yarmush (EItanya) merged 1 commit into
Eitan Yarmush (EItanya) merged 1 commit into
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besides forwarding, a new namespace picks up the node's accept_redirects, route_localnet, rp_filter, accept_local and accept_source_route, and its links take IPv6 router advertisements and redirects from the actor. pin them SetSysctls now writes every key, since turning forwarding off sets conf/all/accept_redirects back to 1 the sysctls are set before any link is added, a conf/default write doesn't reach existing links for keys the node set explicitly Signed-off-by: Benjamin Elder <[email protected]>
Benjamin Elder (BenTheElder)
requested review from
Eitan Yarmush (EItanya) and
Bowei Du (bowei)
October 27, 2026 14:56
Benjamin Elder (BenTheElder)
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Eitan Yarmush (EItanya)
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Oct 27, 2026
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me as well
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🔵 Needs a closer look
Security-sensitive, kernel-dependent networking changes need human review and privileged test validation on supported kernels for both runtime paths.
No open issues 🎉
What changed in this PR
Hardens actor sandbox networking by explicitly setting inherited namespace sysctls before creating links, covering both gVisor and microVM paths.
Changes:
- Pins forwarding, redirect, source-validation, and IPv6 settings before link creation.
- Makes
SetSysctlswrite every key in order so earlier writes cannot invalidate skipped settings. - Adds tests for explicit writes and per-link settings, including links added after setup.
| File | Description |
|---|---|
internal/netns/sysctl.go |
Writes all requested sysctls in order while preserving remount handling. |
internal/netns/sysctl_linux_test.go |
Updates batch-write tests and checks writes of already-matching values. |
internal/ateworker/actornet/sandbox.go |
Applies sandbox sysctls before creating network links. |
internal/ateworker/actornet/sandbox_linux_test.go |
Checks namespace and per-link settings for both sandbox layouts. |
Review effort: Balanced
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Why is this needed? (Or link the issue. Open one first for features, API, install or CI changes.)
FYI Greg Castle (@destijl), follow-up on #2939 (comment)
Besides forwarding, a new namespace picks up the node's:
accept_redirectsroute_localnetrp_filteraccept_localaccept_source_routeaccept_ra=1.NOTE:
SetSysctlsnow writes every key, since turning forwarding off setsconf/all/accept_redirectsback to 1.The sysctls are set before any link is added, a conf/default write doesn't reach existing links for keys the node set explicitly.
Fixes #2939
AI use: Assisted with identifying the gaps (with upstream sources cited), drafting the change and testing. I read through this before submitting and iterated a bit.