Existing nftables set implementations allow matching entries with interval expressions (rbtree), e.g. 192.0.2.1-192.0.2.4, entries specifying field concatenation (hash, rhash), e.g. 192.0.2.1:22, but not both. In other words, none of the set types allows matching on range expressions for more than one packet field at a time, such as ipset does with types bitmap:ip,mac, and, to a more limited extent (netmasks, not arbitrary ranges), with types hash:net,net, hash:net,port, hash:ip,port,net, and hash:net,port,net. As a pure hash-based approach is unsuitable for matching on ranges, and "proxying" the existing red-black tree type looks impractical as elements would need to be shared and managed across all employed trees, this new set implementation intends to fill the functionality gap by employing a relatively novel approach. The fundamental idea, illustrated in deeper detail in patch 3/8, is to use lookup tables classifying a small number of grouped bits from each field, and map the lookup results in a way that yields a verdict for the full set of specified fields. The grouping bit aspect is loosely inspired by the Grouper algorithm, by Jay Ligatti, Josh Kuhn, and Chris Gage (see patch 3/8 for the full reference). A reference, stand-alone implementation of the algorithm itself is available at: https://pipapo.lameexcu.se Some notes about possible future optimisations are also mentioned there. This algorithm reduces the matching problem to, essentially, a repetitive sequence of simple bitwise operations, and is particularly suitable to be optimised by leveraging SIMD instruction sets. An AVX2-based implementation is also presented in this series. I plan to post the adaptation of the existing AVX2 vectorised implementation for (at least) NEON at a later time. Patch 1/8 implements the needed UAPI bits: additions to the existing interface are kept to a minimum by recycling existing concepts for both ranging and concatenation, as suggested by Florian. Patch 2/8 adds a new bitmap operation that copies the source bitmap onto the destination while removing a given region, and is needed to delete regions of arrays mapping between lookup tables. Patch 3/8 is the actual set implementation. Patch 4/8 introduces selftests for the new implementation. Patch 5/8 provides an easy optimisation with substantial gain on matching rates. Patches 6/8 and 7/8 are preparatory work to add an alternative, vectorised lookup implementation. Patch 8/8 contains the AVX2-based implementation of the lookup routines. The nftables and libnftnl counterparts depend on changes to the UAPI header file included in patch 1/8. Credits go to Jay Ligatti, Josh Kuhn, and Chris Gage for their original Grouper implementation and article from ICCCN proceedings (see reference in patch 3/8), and to Daniel Lemire for his public domain implementation of a fast iterator on set bits using built-in implementations of the CTZL operation, also included in patch 3/8. Special thanks go to Florian Westphal for all the nftables consulting and the original interface idea, to Sabrina Dubroca for support with RCU and bit manipulation topics, to Eric Garver for an early review, and to Phil Sutter for reaffirming the need for the use case covered here. v2: changes listed in messages for 3/8 and 8/8 Stefano Brivio (8): netfilter: nf_tables: Support for subkeys, set with multiple ranged fields bitmap: Introduce bitmap_cut(): cut bits and shift remaining nf_tables: Add set type for arbitrary concatenation of ranges selftests: netfilter: Introduce tests for sets with range concatenation nft_set_pipapo: Provide unrolled lookup loops for common field sizes nft_set_pipapo: Prepare for vectorised implementation: alignment nft_set_pipapo: Prepare for vectorised implementation: helpers nft_set_pipapo: Introduce AVX2-based lookup implementation include/linux/bitmap.h | 4 + include/net/netfilter/nf_tables_core.h | 2 + include/uapi/linux/netfilter/nf_tables.h | 16 + lib/bitmap.c | 66 + net/netfilter/Makefile | 6 +- net/netfilter/nf_tables_api.c | 4 +- net/netfilter/nf_tables_set_core.c | 8 + net/netfilter/nft_set_pipapo.c | 2165 +++++++++++++++++ net/netfilter/nft_set_pipapo.h | 236 ++ net/netfilter/nft_set_pipapo_avx2.c | 838 +++++++ net/netfilter/nft_set_pipapo_avx2.h | 14 + tools/testing/selftests/netfilter/Makefile | 3 +- .../selftests/netfilter/nft_concat_range.sh | 1481 +++++++++++ 13 files changed, 4839 insertions(+), 4 deletions(-) create mode 100644 net/netfilter/nft_set_pipapo.c create mode 100644 net/netfilter/nft_set_pipapo.h create mode 100644 net/netfilter/nft_set_pipapo_avx2.c create mode 100644 net/netfilter/nft_set_pipapo_avx2.h create mode 100755 tools/testing/selftests/netfilter/nft_concat_range.sh -- 2.20.1
