net/netfilter/nft_set_pipapo.h

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #ifndef _NFT_SET_PIPAPO_H
   4
   5 #include <linux/log2.h>
   6 #include <net/ipv6.h>                   /* For the maximum length of a field */
   7
   8 /* Count of concatenated fields depends on count of 32-bit nftables registers */
   9 #define NFT_PIPAPO_MAX_FIELDS           NFT_REG32_COUNT
  10
  11 /* Restrict usage to multiple fields, make sure rbtree is used otherwise */
  12 #define NFT_PIPAPO_MIN_FIELDS           2
  13
  14 /* Largest supported field size */
  15 #define NFT_PIPAPO_MAX_BYTES            (sizeof(struct in6_addr))
  16 #define NFT_PIPAPO_MAX_BITS             (NFT_PIPAPO_MAX_BYTES * BITS_PER_BYTE)
  17
  18 /* Bits to be grouped together in table buckets depending on set size */
  19 #define NFT_PIPAPO_GROUP_BITS_INIT      NFT_PIPAPO_GROUP_BITS_SMALL_SET
  20 #define NFT_PIPAPO_GROUP_BITS_SMALL_SET 8
  21 #define NFT_PIPAPO_GROUP_BITS_LARGE_SET 4
  22 #define NFT_PIPAPO_GROUP_BITS_ARE_8_OR_4                                \
  23         BUILD_BUG_ON((NFT_PIPAPO_GROUP_BITS_SMALL_SET != 8) ||          \
  24                      (NFT_PIPAPO_GROUP_BITS_LARGE_SET != 4))
  25 #define NFT_PIPAPO_GROUPS_PER_BYTE(f)   (BITS_PER_BYTE / (f)->bb)
  26
  27 /* If a lookup table gets bigger than NFT_PIPAPO_LT_SIZE_HIGH, switch to the
  28  * small group width, and switch to the big group width if the table gets
  29  * smaller than NFT_PIPAPO_LT_SIZE_LOW.
  30  *
  31  * Picking 2MiB as threshold (for a single table) avoids as much as possible
  32  * crossing page boundaries on most architectures (x86-64 and MIPS huge pages,
  33  * ARMv7 supersections, POWER "large" pages, SPARC Level 1 regions, etc.), which
  34  * keeps performance nice in case kvmalloc() gives us non-contiguous areas.
  35  */
  36 #define NFT_PIPAPO_LT_SIZE_THRESHOLD    (1 << 21)
  37 #define NFT_PIPAPO_LT_SIZE_HYSTERESIS   (1 << 16)
  38 #define NFT_PIPAPO_LT_SIZE_HIGH         NFT_PIPAPO_LT_SIZE_THRESHOLD
  39 #define NFT_PIPAPO_LT_SIZE_LOW          NFT_PIPAPO_LT_SIZE_THRESHOLD -  \
  40                                         NFT_PIPAPO_LT_SIZE_HYSTERESIS
  41
  42 /* Fields are padded to 32 bits in input registers */
  43 #define NFT_PIPAPO_GROUPS_PADDED_SIZE(f)                                \
  44         (round_up((f)->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f), sizeof(u32)))
  45 #define NFT_PIPAPO_GROUPS_PADDING(f)                                    \
  46         (NFT_PIPAPO_GROUPS_PADDED_SIZE(f) - (f)->groups /               \
  47                                             NFT_PIPAPO_GROUPS_PER_BYTE(f))
  48
  49 /* Number of buckets given by 2 ^ n, with n bucket bits */
  50 #define NFT_PIPAPO_BUCKETS(bb)          (1 << (bb))
  51
  52 /* Each n-bit range maps to up to n * 2 rules */
  53 #define NFT_PIPAPO_MAP_NBITS            (const_ilog2(NFT_PIPAPO_MAX_BITS * 2))
  54
  55 /* Use the rest of mapping table buckets for rule indices, but it makes no sense
  56  * to exceed 32 bits
  57  */
  58 #if BITS_PER_LONG == 64
  59 #define NFT_PIPAPO_MAP_TOBITS           32
  60 #else
  61 #define NFT_PIPAPO_MAP_TOBITS           (BITS_PER_LONG - NFT_PIPAPO_MAP_NBITS)
  62 #endif
  63
  64 /* ...which gives us the highest allowed index for a rule */
  65 #define NFT_PIPAPO_RULE0_MAX            ((1UL << (NFT_PIPAPO_MAP_TOBITS - 1)) \
  66                                         - (1UL << NFT_PIPAPO_MAP_NBITS))
  67
  68 /* Definitions for vectorised implementations */
  69 #ifdef NFT_PIPAPO_ALIGN
  70 #define NFT_PIPAPO_ALIGN_HEADROOM                                       \
  71         (NFT_PIPAPO_ALIGN - ARCH_KMALLOC_MINALIGN)
  72 #define NFT_PIPAPO_LT_ALIGN(lt)         (PTR_ALIGN((lt), NFT_PIPAPO_ALIGN))
  73 #define NFT_PIPAPO_LT_ASSIGN(field, x)                                  \
  74         do {                                                            \
  75                 (field)->lt_aligned = NFT_PIPAPO_LT_ALIGN(x);           \
  76                 (field)->lt = (x);                                      \
  77         } while (0)
  78 #else
  79 #define NFT_PIPAPO_ALIGN_HEADROOM       0
  80 #define NFT_PIPAPO_LT_ALIGN(lt)         (lt)
  81 #define NFT_PIPAPO_LT_ASSIGN(field, x)  ((field)->lt = (x))
  82 #endif /* NFT_PIPAPO_ALIGN */
  83
  84 #define nft_pipapo_for_each_field(field, index, match)          \
  85         for ((field) = (match)->f, (index) = 0;                 \
  86              (index) < (match)->field_count;                    \
  87              (index)++, (field)++)
  88
  89 /**
  90  * union nft_pipapo_map_bucket - Bucket of mapping table
  91  * @to:         First rule number (in next field) this rule maps to
  92  * @n:          Number of rules (in next field) this rule maps to
  93  * @e:          If there's no next field, pointer to element this rule maps to
  94  */
  95 union nft_pipapo_map_bucket {
  96         struct {
  97 #if BITS_PER_LONG == 64
  98                 static_assert(NFT_PIPAPO_MAP_TOBITS <= 32);
  99                 u32 to;
 100
 101                 static_assert(NFT_PIPAPO_MAP_NBITS <= 32);
 102                 u32 n;
 103 #else
 104                 unsigned long to:NFT_PIPAPO_MAP_TOBITS;
 105                 unsigned long  n:NFT_PIPAPO_MAP_NBITS;
 106 #endif
 107         };
 108         struct nft_pipapo_elem *e;
 109 };
 110
 111 /**
 112  * struct nft_pipapo_field - Lookup, mapping tables and related data for a field
 113  * @groups:     Amount of bit groups
 114  * @rules:      Number of inserted rules
 115  * @bsize:      Size of each bucket in lookup table, in longs
 116  * @bb:         Number of bits grouped together in lookup table buckets
 117  * @lt:         Lookup table: 'groups' rows of buckets
 118  * @lt_aligned: Version of @lt aligned to NFT_PIPAPO_ALIGN bytes
 119  * @mt:         Mapping table: one bucket per rule
 120  */
 121 struct nft_pipapo_field {
 122         int groups;
 123         unsigned long rules;
 124         size_t bsize;
 125         int bb;
 126 #ifdef NFT_PIPAPO_ALIGN
 127         unsigned long *lt_aligned;
 128 #endif
 129         unsigned long *lt;
 130         union nft_pipapo_map_bucket *mt;
 131 };
 132
 133 /**
 134  * struct nft_pipapo_match - Data used for lookup and matching
 135  * @field_count         Amount of fields in set
 136  * @scratch:            Preallocated per-CPU maps for partial matching results
 137  * @scratch_aligned:    Version of @scratch aligned to NFT_PIPAPO_ALIGN bytes
 138  * @bsize_max:          Maximum lookup table bucket size of all fields, in longs
 139  * @rcu                 Matching data is swapped on commits
 140  * @f:                  Fields, with lookup and mapping tables
 141  */
 142 struct nft_pipapo_match {
 143         int field_count;
 144 #ifdef NFT_PIPAPO_ALIGN
 145         unsigned long * __percpu *scratch_aligned;
 146 #endif
 147         unsigned long * __percpu *scratch;
 148         size_t bsize_max;
 149         struct rcu_head rcu;
 150         struct nft_pipapo_field f[];
 151 };
 152
 153 /**
 154  * struct nft_pipapo - Representation of a set
 155  * @match:      Currently in-use matching data
 156  * @clone:      Copy where pending insertions and deletions are kept
 157  * @width:      Total bytes to be matched for one packet, including padding
 158  * @dirty:      Working copy has pending insertions or deletions
 159  * @last_gc:    Timestamp of last garbage collection run, jiffies
 160  */
 161 struct nft_pipapo {
 162         struct nft_pipapo_match __rcu *match;
 163         struct nft_pipapo_match *clone;
 164         int width;
 165         bool dirty;
 166         unsigned long last_gc;
 167 };
 168
 169 struct nft_pipapo_elem;
 170
 171 /**
 172  * struct nft_pipapo_elem - API-facing representation of single set element
 173  * @ext:        nftables API extensions
 174  */
 175 struct nft_pipapo_elem {
 176         struct nft_set_ext ext;
 177 };
 178
 179 int pipapo_refill(unsigned long *map, int len, int rules, unsigned long *dst,
 180                   union nft_pipapo_map_bucket *mt, bool match_only);
 181
 182 /**
 183  * pipapo_and_field_buckets_4bit() - Intersect 4-bit buckets
 184  * @f:          Field including lookup table
 185  * @dst:        Area to store result
 186  * @data:       Input data selecting table buckets
 187  */
 188 static inline void pipapo_and_field_buckets_4bit(struct nft_pipapo_field *f,
 189                                                  unsigned long *dst,
 190                                                  const u8 *data)
 191 {
 192         unsigned long *lt = NFT_PIPAPO_LT_ALIGN(f->lt);
 193         int group;
 194
 195         for (group = 0; group < f->groups; group += BITS_PER_BYTE / 4, data++) {
 196                 u8 v;
 197
 198                 v = *data >> 4;
 199                 __bitmap_and(dst, dst, lt + v * f->bsize,
 200                              f->bsize * BITS_PER_LONG);
 201                 lt += f->bsize * NFT_PIPAPO_BUCKETS(4);
 202
 203                 v = *data & 0x0f;
 204                 __bitmap_and(dst, dst, lt + v * f->bsize,
 205                              f->bsize * BITS_PER_LONG);
 206                 lt += f->bsize * NFT_PIPAPO_BUCKETS(4);
 207         }
 208 }
 209
 210 /**
 211  * pipapo_and_field_buckets_8bit() - Intersect 8-bit buckets
 212  * @f:          Field including lookup table
 213  * @dst:        Area to store result
 214  * @data:       Input data selecting table buckets
 215  */
 216 static inline void pipapo_and_field_buckets_8bit(struct nft_pipapo_field *f,
 217                                                  unsigned long *dst,
 218                                                  const u8 *data)
 219 {
 220         unsigned long *lt = NFT_PIPAPO_LT_ALIGN(f->lt);
 221         int group;
 222
 223         for (group = 0; group < f->groups; group++, data++) {
 224                 __bitmap_and(dst, dst, lt + *data * f->bsize,
 225                              f->bsize * BITS_PER_LONG);
 226                 lt += f->bsize * NFT_PIPAPO_BUCKETS(8);
 227         }
 228 }
 229
 230 /**
 231  * pipapo_estimate_size() - Estimate worst-case for set size
 232  * @desc:       Set description, element count and field description used here
 233  *
 234  * The size for this set type can vary dramatically, as it depends on the number
 235  * of rules (composing netmasks) the entries expand to. We compute the worst
 236  * case here.
 237  *
 238  * In general, for a non-ranged entry or a single composing netmask, we need
 239  * one bit in each of the sixteen NFT_PIPAPO_BUCKETS, for each 4-bit group (that
 240  * is, each input bit needs four bits of matching data), plus a bucket in the
 241  * mapping table for each field.
 242  *
 243  * Return: worst-case set size in bytes, 0 on any overflow
 244  */
 245 static u64 pipapo_estimate_size(const struct nft_set_desc *desc)
 246 {
 247         unsigned long entry_size;
 248         u64 size;
 249         int i;
 250
 251         for (i = 0, entry_size = 0; i < desc->field_count; i++) {
 252                 unsigned long rules;
 253
 254                 if (desc->field_len[i] > NFT_PIPAPO_MAX_BYTES)
 255                         return 0;
 256
 257                 /* Worst-case ranges for each concatenated field: each n-bit
 258                  * field can expand to up to n * 2 rules in each bucket, and
 259                  * each rule also needs a mapping bucket.
 260                  */
 261                 rules = ilog2(desc->field_len[i] * BITS_PER_BYTE) * 2;
 262                 entry_size += rules *
 263                               NFT_PIPAPO_BUCKETS(NFT_PIPAPO_GROUP_BITS_INIT) /
 264                               BITS_PER_BYTE;
 265                 entry_size += rules * sizeof(union nft_pipapo_map_bucket);
 266         }
 267
 268         /* Rules in lookup and mapping tables are needed for each entry */
 269         size = desc->size * entry_size;
 270         if (size && div_u64(size, desc->size) != entry_size)
 271                 return 0;
 272
 273         size += sizeof(struct nft_pipapo) + sizeof(struct nft_pipapo_match) * 2;
 274
 275         size += sizeof(struct nft_pipapo_field) * desc->field_count;
 276
 277         return size;
 278 }
 279
 280 #endif /* _NFT_SET_PIPAPO_H */