expr: hash: support of symmetric hash

This patch provides symmetric hash support according to source
ip address and port, and destination ip address and port.

The new attribute NFTA_HASH_TYPE has been included to support
different types of hashing functions. Currently supported
NFT_HASH_JENKINS through jhash and NFT_HASH_SYM through symhash.

The main difference between both types are:
 - jhash requires an expression with sreg, symhash doesn't.
 - symhash supports modulus and offset, but not seed.

Examples:

 nft add rule ip nat prerouting ct mark set jhash ip saddr mod 2
 nft add rule ip nat prerouting ct mark set symhash mod 2

Signed-off-by: Laura Garcia Liebana <laura.garcia@zevenet.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 7d327eaf457d0c5de893dd024d00c7e06e3489cc..b06d1b176578a679a7c5e0edaaa86c296b6ac2c8 100644 (file)
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -229,6 +229,7 @@ enum {
        NFTNL_EXPR_HASH_MODULUS,
        NFTNL_EXPR_HASH_SEED,
        NFTNL_EXPR_HASH_OFFSET,
+       NFTNL_EXPR_HASH_TYPE,
 };
 
 enum {

diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index 05215d30fe5c9853b7871e799ccdce4878a04ef1..4f7d75682c5917cf9b26e70d9ac09b2e02d8ed7c 100644 (file)
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -815,6 +815,17 @@ enum nft_rt_keys {
        NFT_RT_NEXTHOP6,
 };
 
+/**
+ * enum nft_hash_types - nf_tables hash expression types
+ *
+ * @NFT_HASH_JENKINS: Jenkins Hash
+ * @NFT_HASH_SYM: Symmetric Hash
+ */
+enum nft_hash_types {
+       NFT_HASH_JENKINS,
+       NFT_HASH_SYM,
+};
+
 /**
  * enum nft_hash_attributes - nf_tables hash expression netlink attributes
  *
@@ -824,6 +835,7 @@ enum nft_rt_keys {
  * @NFTA_HASH_MODULUS: modulus value (NLA_U32)
  * @NFTA_HASH_SEED: seed value (NLA_U32)
  * @NFTA_HASH_OFFSET: add this offset value to hash result (NLA_U32)
+ * @NFTA_HASH_TYPE: hash operation (NLA_U32: nft_hash_types)
  */
 enum nft_hash_attributes {
        NFTA_HASH_UNSPEC,
@@ -833,6 +845,7 @@ enum nft_hash_attributes {
        NFTA_HASH_MODULUS,
        NFTA_HASH_SEED,
        NFTA_HASH_OFFSET,
+       NFTA_HASH_TYPE,
        __NFTA_HASH_MAX,
 };
 #define NFTA_HASH_MAX  (__NFTA_HASH_MAX - 1)

diff --git a/src/expr/hash.c b/src/expr/hash.c
index 83f93179c26dae7a0775213db825b0499439ebd5..d870510790642db7595ee77b32c8531cb8dfd0a3 100644 (file)
--- a/src/expr/hash.c
+++ b/src/expr/hash.c
@@ -21,6 +21,7 @@
 #include <libnftnl/rule.h>
 
 struct nftnl_expr_hash {
+       enum nft_hash_types     type;
        enum nft_registers      sreg;
        enum nft_registers      dreg;
        unsigned int            len;
@@ -34,7 +35,6 @@ nftnl_expr_hash_set(struct nftnl_expr *e, uint16_t type,
                    const void *data, uint32_t data_len)
 {
        struct nftnl_expr_hash *hash = nftnl_expr_data(e);
-
        switch (type) {
        case NFTNL_EXPR_HASH_SREG:
                hash->sreg = *((uint32_t *)data);
@@ -54,6 +54,9 @@ nftnl_expr_hash_set(struct nftnl_expr *e, uint16_t type,
        case NFTNL_EXPR_HASH_OFFSET:
                hash->offset = *((uint32_t *)data);
                break;
+       case NFTNL_EXPR_HASH_TYPE:
+               hash->type = *((uint32_t *)data);
+               break;
        default:
                return -1;
        }
@@ -85,6 +88,9 @@ nftnl_expr_hash_get(const struct nftnl_expr *e, uint16_t type,
        case NFTNL_EXPR_HASH_OFFSET:
                *data_len = sizeof(hash->offset);
                return &hash->offset;
+       case NFTNL_EXPR_HASH_TYPE:
+               *data_len = sizeof(hash->type);
+               return &hash->type;
        }
        return NULL;
 }
@@ -104,6 +110,7 @@ static int nftnl_expr_hash_cb(const struct nlattr *attr, void *data)
        case NFTA_HASH_MODULUS:
        case NFTA_HASH_SEED:
        case NFTA_HASH_OFFSET:
+       case NFTA_HASH_TYPE:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        abi_breakage();
                break;
@@ -130,6 +137,8 @@ nftnl_expr_hash_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
                mnl_attr_put_u32(nlh, NFTA_HASH_SEED, htonl(hash->seed));
        if (e->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
                mnl_attr_put_u32(nlh, NFTA_HASH_OFFSET, htonl(hash->offset));
+       if (e->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+               mnl_attr_put_u32(nlh, NFTA_HASH_TYPE, htonl(hash->type));
 }
 
 static int
@@ -166,6 +175,10 @@ nftnl_expr_hash_parse(struct nftnl_expr *e, struct nlattr *attr)
                hash->offset = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_OFFSET]));
                e->flags |= (1 << NFTNL_EXPR_HASH_OFFSET);
        }
+       if (tb[NFTA_HASH_TYPE]) {
+               hash->type = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_TYPE]));
+               e->flags |= (1 << NFTNL_EXPR_HASH_TYPE);
+       }
 
        return ret;
 }
@@ -174,7 +187,7 @@ static int nftnl_expr_hash_json_parse(struct nftnl_expr *e, json_t *root,
                                      struct nftnl_parse_err *err)
 {
 #ifdef JSON_PARSING
-       uint32_t sreg, dreg, len, modulus, seed, offset;
+       uint32_t sreg, dreg, len, modulus, seed, offset, type;
 
        if (nftnl_jansson_parse_reg(root, "sreg", NFTNL_TYPE_U32,
                                    &sreg, err) == 0)
@@ -200,6 +213,10 @@ static int nftnl_expr_hash_json_parse(struct nftnl_expr *e, json_t *root,
                                    &offset, err) == 0)
                nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_OFFSET, offset);
 
+       if (nftnl_jansson_parse_val(root, "type", NFTNL_TYPE_U32,
+                                   &type, err) == 0)
+               nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_TYPE, type);
+
        return 0;
 #else
        errno = EOPNOTSUPP;
@@ -214,10 +231,23 @@ nftnl_expr_hash_snprintf_default(char *buf, size_t size,
        struct nftnl_expr_hash *hash = nftnl_expr_data(e);
        int len = size, offset = 0, ret;
 
-       ret = snprintf(buf, len, "reg %u = jhash(reg %u, %u, 0x%x) %% mod %u ",
-                      hash->dreg, hash->sreg, hash->len, hash->seed,
-                      hash->modulus);
-       SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       switch (hash->type) {
+       case NFT_HASH_SYM:
+               ret =
+               snprintf(buf, len, "reg %u = symhash() %% mod %u ", hash->dreg,
+                        hash->modulus);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+               break;
+       case NFT_HASH_JENKINS:
+       default:
+               ret =
+               snprintf(buf, len,
+                        "reg %u = jhash(reg %u, %u, 0x%x) %% mod %u ",
+                        hash->dreg, hash->sreg, hash->len, hash->seed,
+                        hash->modulus);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+               break;
+       }
 
        if (hash->offset) {
                ret = snprintf(buf + offset, len, "offset %u ", hash->offset);
@@ -246,6 +276,8 @@ static int nftnl_expr_hash_export(char *buf, size_t size,
                nftnl_buf_u32(&b, type, hash->seed, SEED);
        if (e->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
                nftnl_buf_u32(&b, type, hash->offset, OFFSET);
+       if (e->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+               nftnl_buf_u32(&b, type, hash->type, TYPE);
 
        return nftnl_buf_done(&b);
 }
@@ -285,6 +317,8 @@ static bool nftnl_expr_hash_cmp(const struct nftnl_expr *e1,
                eq &= (h1->seed == h2->seed);
        if (e1->flags & (1 << NFTNL_EXPR_HASH_OFFSET))
                eq &= (h1->offset == h2->offset);
+       if (e1->flags & (1 << NFTNL_EXPR_HASH_TYPE))
+               eq &= (h1->type == h2->type);
 
        return eq;
 }

diff --git a/tests/nft-expr_hash-test.c b/tests/nft-expr_hash-test.c
index d92823460943c4e8bd801d96f94a5ca9ee168aee..7be6e9efd8c3579e5732ecfb930337e65a5b8a6e 100644 (file)
--- a/tests/nft-expr_hash-test.c
+++ b/tests/nft-expr_hash-test.c
@@ -45,6 +45,9 @@ static void cmp_nftnl_expr(struct nftnl_expr *rule_a,
        if (nftnl_expr_get_u32(rule_a, NFTNL_EXPR_HASH_OFFSET) !=
            nftnl_expr_get_u32(rule_b, NFTNL_EXPR_HASH_OFFSET))
                print_err("Expr NFTNL_EXPR_HASH_OFFSET mismatches");
+       if (nftnl_expr_get_u32(rule_a, NFTNL_EXPR_HASH_TYPE) !=
+           nftnl_expr_get_u32(rule_b, NFTNL_EXPR_HASH_TYPE))
+               print_err("Expr NFTNL_EXPR_HASH_TYPE mismatches");
 }
 
 int main(int argc, char *argv[])
@@ -69,6 +72,7 @@ int main(int argc, char *argv[])
        nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_MODULUS, 0x78123456);
        nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_SEED, 0x78123456);
        nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_OFFSET, 0x3612845);
+       nftnl_expr_set_u32(ex, NFTNL_EXPR_HASH_TYPE, NFT_HASH_JENKINS);
 
        nftnl_rule_add_expr(a, ex);