/* * Copyright (c) 2017 Pablo Neira Ayuso * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include /* This bitmap uses two bits to represent one element. These two bits determine * the element state in the current and the future generation. * * An element can be in three states. The generation cursor is represented using * the ^ character, note that this cursor shifts on every succesful transaction. * If no transaction is going on, we observe all elements are in the following * state: * * 11 = this element is active in the current generation. In case of no updates, * ^ it stays active in the next generation. * 00 = this element is inactive in the current generation. In case of no * ^ updates, it stays inactive in the next generation. * * On transaction handling, we observe these two temporary states: * * 01 = this element is inactive in the current generation and it becomes active * ^ in the next one. This happens when the element is inserted but commit * path has not yet been executed yet, so activation is still pending. On * transaction abortion, the element is removed. * 10 = this element is active in the current generation and it becomes inactive * ^ in the next one. This happens when the element is deactivated but commit * path has not yet been executed yet, so removal is still pending. On * transation abortion, the next generation bit is reset to go back to * restore its previous state. */ struct nft_bitmap { u16 bitmap_size; u8 bitmap[]; }; static inline void nft_bitmap_location(u32 key, u32 *idx, u32 *off) { u32 k = (key << 1); *idx = k / BITS_PER_BYTE; *off = k % BITS_PER_BYTE; } /* Fetch the two bits that represent the element and check if it is active based * on the generation mask. */ static inline bool nft_bitmap_active(const u8 *bitmap, u32 idx, u32 off, u8 genmask) { return (bitmap[idx] & (0x3 << off)) & (genmask << off); } static bool nft_bitmap_lookup(const struct net *net, const struct nft_set *set, const u32 *key, const struct nft_set_ext **ext) { const struct nft_bitmap *priv = nft_set_priv(set); u8 genmask = nft_genmask_cur(net); u32 idx, off; nft_bitmap_location(*key, &idx, &off); return nft_bitmap_active(priv->bitmap, idx, off, genmask); } static int nft_bitmap_insert(const struct net *net, const struct nft_set *set, const struct nft_set_elem *elem, struct nft_set_ext **_ext) { struct nft_bitmap *priv = nft_set_priv(set); struct nft_set_ext *ext = elem->priv; u8 genmask = nft_genmask_next(net); u32 idx, off; nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off); if (nft_bitmap_active(priv->bitmap, idx, off, genmask)) return -EEXIST; /* Enter 01 state. */ priv->bitmap[idx] |= (genmask << off); return 0; } static void nft_bitmap_remove(const struct net *net, const struct nft_set *set, const struct nft_set_elem *elem) { struct nft_bitmap *priv = nft_set_priv(set); struct nft_set_ext *ext = elem->priv; u8 genmask = nft_genmask_next(net); u32 idx, off; nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off); /* Enter 00 state. */ priv->bitmap[idx] &= ~(genmask << off); } static void nft_bitmap_activate(const struct net *net, const struct nft_set *set, const struct nft_set_elem *elem) { struct nft_bitmap *priv = nft_set_priv(set); struct nft_set_ext *ext = elem->priv; u8 genmask = nft_genmask_next(net); u32 idx, off; nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off); /* Enter 11 state. */ priv->bitmap[idx] |= (genmask << off); } static bool nft_bitmap_flush(const struct net *net, const struct nft_set *set, void *ext) { struct nft_bitmap *priv = nft_set_priv(set); u8 genmask = nft_genmask_next(net); u32 idx, off; nft_bitmap_location(nft_set_ext_key(ext)->data[0], &idx, &off); /* Enter 10 state, similar to deactivation. */ priv->bitmap[idx] &= ~(genmask << off); return true; } static struct nft_set_ext *nft_bitmap_ext_alloc(const struct nft_set *set, const struct nft_set_elem *elem) { struct nft_set_ext_tmpl tmpl; struct nft_set_ext *ext; nft_set_ext_prepare(&tmpl); nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen); ext = kzalloc(tmpl.len, GFP_KERNEL); if (!ext) return NULL; nft_set_ext_init(ext, &tmpl); memcpy(nft_set_ext_key(ext), elem->key.val.data, set->klen); return ext; } static void *nft_bitmap_deactivate(const struct net *net, const struct nft_set *set, const struct nft_set_elem *elem) { struct nft_bitmap *priv = nft_set_priv(set); u8 genmask = nft_genmask_next(net); struct nft_set_ext *ext; u32 idx, off, key = 0; memcpy(&key, elem->key.val.data, set->klen); nft_bitmap_location(key, &idx, &off); if (!nft_bitmap_active(priv->bitmap, idx, off, genmask)) return NULL; /* We have no real set extension since this is a bitmap, allocate this * dummy object that is released from the commit/abort path. */ ext = nft_bitmap_ext_alloc(set, elem); if (!ext) return NULL; /* Enter 10 state. */ priv->bitmap[idx] &= ~(genmask << off); return ext; } static void nft_bitmap_walk(const struct nft_ctx *ctx, struct nft_set *set, struct nft_set_iter *iter) { const struct nft_bitmap *priv = nft_set_priv(set); struct nft_set_ext_tmpl tmpl; struct nft_set_elem elem; struct nft_set_ext *ext; int idx, off; u16 key; nft_set_ext_prepare(&tmpl); nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen); for (idx = 0; idx < priv->bitmap_size; idx++) { for (off = 0; off < BITS_PER_BYTE; off += 2) { if (iter->count < iter->skip) goto cont; if (!nft_bitmap_active(priv->bitmap, idx, off, iter->genmask)) goto cont; ext = kzalloc(tmpl.len, GFP_KERNEL); if (!ext) { iter->err = -ENOMEM; return; } nft_set_ext_init(ext, &tmpl); key = ((idx * BITS_PER_BYTE) + off) >> 1; memcpy(nft_set_ext_key(ext), &key, set->klen); elem.priv = ext; iter->err = iter->fn(ctx, set, iter, &elem); /* On set flush, this dummy extension object is released * from the commit/abort path. */ if (!iter->flush) kfree(ext); if (iter->err < 0) return; cont: iter->count++; } } } /* The bitmap size is pow(2, key length in bits) / bits per byte. This is * multiplied by two since each element takes two bits. For 8 bit keys, the * bitmap consumes 66 bytes. For 16 bit keys, 16388 bytes. */ static inline u32 nft_bitmap_size(u32 klen) { return ((2 << ((klen * BITS_PER_BYTE) - 1)) / BITS_PER_BYTE) << 1; } static inline u32 nft_bitmap_total_size(u32 klen) { return sizeof(struct nft_bitmap) + nft_bitmap_size(klen); } static unsigned int nft_bitmap_privsize(const struct nlattr * const nla[]) { u32 klen = ntohl(nla_get_be32(nla[NFTA_SET_KEY_LEN])); return nft_bitmap_total_size(klen); } static int nft_bitmap_init(const struct nft_set *set, const struct nft_set_desc *desc, const struct nlattr * const nla[]) { struct nft_bitmap *priv = nft_set_priv(set); priv->bitmap_size = nft_bitmap_size(set->klen); return 0; } static void nft_bitmap_destroy(const struct nft_set *set) { } static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features, struct nft_set_estimate *est) { /* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */ if (desc->klen > 2) return false; est->size = nft_bitmap_total_size(desc->klen); est->lookup = NFT_SET_CLASS_O_1; est->space = NFT_SET_CLASS_O_1; return true; } static struct nft_set_ops nft_bitmap_ops __read_mostly = { .privsize = nft_bitmap_privsize, .estimate = nft_bitmap_estimate, .init = nft_bitmap_init, .destroy = nft_bitmap_destroy, .insert = nft_bitmap_insert, .remove = nft_bitmap_remove, .deactivate = nft_bitmap_deactivate, .flush = nft_bitmap_flush, .activate = nft_bitmap_activate, .lookup = nft_bitmap_lookup, .walk = nft_bitmap_walk, .owner = THIS_MODULE, }; static int __init nft_bitmap_module_init(void) { return nft_register_set(&nft_bitmap_ops); } static void __exit nft_bitmap_module_exit(void) { nft_unregister_set(&nft_bitmap_ops); } module_init(nft_bitmap_module_init); module_exit(nft_bitmap_module_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Pablo Neira Ayuso "); MODULE_ALIAS_NFT_SET();