[dpd, mcast] Tighten multicast group and source validation - #364
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This work constrains group and SSM source validation based on a variety of specs, linked throughout the PR. Previously, DPD was accepting groups and (S, G) sources that no packet could actually exercise, including ones that can never leave a host/link or, worse, sources a switch can't forward. Here's the list (the first classifier one was the most obvious): | address | verdict | spec | |--------------------------------|---------|-------------------------------| | ff3x::/32 in ff30::/12 only | is SSM | RFC 4607 §1; RFC 3306 is ASM | | ff3x:: group ID > 0x40000000 | accept | RFC 4607 §4.3 | | v6 scopes other than 4/5/8/e | reject | RFC 7346; no Ethernet realm | | class E (240.0.0.0/4) source | reject | RFC 6890 "Source: False" | | 0.0.0.0/8 source | reject | RFC 6890 "Forwardable: False" | | 100.64.0.0/10 source | accept | RFC 6598, operator-internal | | source/group family mismatch | reject | (local choice) | | 232.0.0.0 (SSM null) | reject | RFC 4607 §4.3 | | v4-mapped/compat v6 source | reject | RFC 4291 §2.5.5, aliases IPv4 |
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This work constrains group and SSM source validation based on a variety of specs, linked throughout the PR. Previously, DPD was accepting groups and (S, G) sources that no packet could actually exercise, including ones that can never leave a host/link or, worse, sources a switch can't forward.
Here's the list (the first classifier one was the most obvious):