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fix(sandbox2): strip IPv6 /etc/hosts entries when the kernel has no IPv6 stack - #1830
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…Pv6 stack On a VM host the guest kernel boots with ipv6.disable=1, but the base image's /etc/hosts still ships IPv6 entries. Resolvers then hand out ::1 for localhost, and programs that try to bind ::1 or :: fail with EAFNOSUPPORT. Detect the disabled stack via an absent or empty /proc/net/if_inet6 and strip the IPv6 entries before writing the plan's static hosts entries, leaving native Linux boxes unchanged. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Limit details: You’ve used all 2 included reviews currently available. 📝 WalkthroughWalkthroughOn Linux, the sandbox checks whether IPv6 is available. When IPv6 is disabled, ChangesHosts File Filtering
Priority: ➖ Normal Estimated code review effort: 2 (Simple) | ~10 minutes Change: Bug fix Suggested reviewers: Merge Risk: ⚪ Minimal · up to The previously identified hosts-file failures are addressed. No actionable merge-blocking risk remains after normal checks. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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A rabbit checks the hosts file at night. Comment |
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- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @crates/sandbox2/src/lib.rs:
- Around line 2947-2948: Update the IPv6 detection in the resolver line parser
to parse fields[0] as an Ipv6Addr instead of requiring it to start with a
hexadecimal digit. This must recognize addresses such as ::1 and remove their
matching localhost entry.
- Around line 2952-2954: Update the IPv4-line handling near the
`fields.iter().any` predicate to filter out only `ip6-*` aliases while retaining
the address and all other names, including `localhost`; do not discard the
entire line when an IPv6 alias is present.
- Around line 2896-2898: Update write_hosts so the empty-static-entry check does
not bypass IPv6 filtering: apply strip_ipv6_hosts_entries when ipv6_disabled()
is true, then return without writing only if the plan is empty and filtering
left the content unchanged. Write the hosts file when filtering removes shipped
entries, while preserving the existing behavior for non-empty plans.
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crates/sandbox2/src/lib.rs
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Recognise ::1 and zoned addresses by parsing the address field as Ipv6Addr rather than by its first character, drop only the ip6-* alias from an IPv4 line instead of the whole line, and apply the strip even when the plan carries no static entries. write_hosts takes the probe result as a parameter so tests can drive both paths, and leaves an unchanged file alone.
…s-strip-80c37e44e7b4dcb1
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# Conflicts: # crates/sandbox2/src/lib.rs
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Routing-Key: inbox-route/I_kwDOSUhdos8AAAABUsm-xQ
On a VM host the guest kernel boots with
ipv6.disable=1(set inBASE_KERNEL_CMDLINEincrates/minvmd/src/vm.rs), but the baseimage's
/etc/hostsstill ships IPv6 entries:Resolvers then hand out
::1forlocalhost, and programs that try tobind
::1or::fail withEAFNOSUPPORT.Fix
In
write_hosts(), after reading the shipped/etc/hostsand beforeappending the plan's static entries, detect whether the kernel has no
IPv6 stack (absent or empty
/proc/net/if_inet6) and strip linescontaining IPv6 addresses or
ip6-*aliases. Native Linux boxes areunchanged — the probe returns
falsewhen/proc/net/if_inet6hascontent.
Changes
write_hosts(): callipv6_disabled()andstrip_ipv6_hosts_entries()before appending plan entries
ipv6_disabled(): probe/proc/net/if_inet6on Linux; alwaysfalseon other platforms
strip_ipv6_hosts_entries(): filter out lines with IPv6 addresses(hex digit +
:) andip6-*name aliases; preserve comments, blanklines, and all IPv4 entries
strip_ipv6_hosts_entries_drops_only_ipv6verifies thestripping logic against a representative shipped file
Summary by CodeRabbit