Message ID | 20190730122818.2032-1-bmastbergen@untangle.com |
---|---|
State | Changes Requested |
Delegated to: | Pablo Neira |
Headers | show |
Series | [nft,v2] src: Support maps as left side expressions | expand |
Hi brett, On Tue, Jul 30, 2019 at 08:28:18AM -0400, Brett Mastbergen wrote: > This change allows map expressions on the left side of comparisons: > > nft add rule foo bar ip saddr map @map_a == 22 counter > > It also allows map expressions as the left side expression of other > map expressions: > > nft add rule foo bar ip saddr map @map_a map @map_b == 22 counter This is an interesting usage of the maps from the left-hand side of an expression. I have a fundamental question, that is, how this will be used from rulesets? My impression is that this will result in many rules, e.g. ip saddr map @map_a map @map_b == 22 accept ip saddr map @map_a map @map_b == 21 drop ip saddr map @map_a map @map_b == 20 jump chain_0 ... This means that we need one rule per map lookup. I think this feature will be more useful if this can be combined with verdict maps, so the right hand side could be used to look up for an action. Thanks.
On 08-08-19, Pablo Neira Ayuso wrote: > Hi brett, > > On Tue, Jul 30, 2019 at 08:28:18AM -0400, Brett Mastbergen wrote: > > This change allows map expressions on the left side of comparisons: > > > > nft add rule foo bar ip saddr map @map_a == 22 counter > > > > It also allows map expressions as the left side expression of other > > map expressions: > > > > nft add rule foo bar ip saddr map @map_a map @map_b == 22 counter > > This is an interesting usage of the maps from the left-hand side of an > expression. > > I have a fundamental question, that is, how this will be used from > rulesets? My impression is that this will result in many rules, e.g. > > ip saddr map @map_a map @map_b == 22 accept > ip saddr map @map_a map @map_b == 21 drop > ip saddr map @map_a map @map_b == 20 jump chain_0 > ... > > This means that we need one rule per map lookup. > > I think this feature will be more useful if this can be combined with > verdict maps, so the right hand side could be used to look up for an > action. > Thats a good point. I bet a map expression could feed into a verdict map without too much trouble. I'll take a look. > Thanks.
diff --git a/src/evaluate.c b/src/evaluate.c index 48c65cd2..59538f27 100644 --- a/src/evaluate.c +++ b/src/evaluate.c @@ -1385,6 +1385,7 @@ static int expr_evaluate_map(struct eval_ctx *ctx, struct expr **expr) !set_is_datamap(map->mappings->set->flags)) return expr_error(ctx->msgs, map->mappings, "Expression is not a map"); + expr_set_context(&ctx->ectx, map->mappings->set->datatype, map->mappings->set->datalen); break; default: BUG("invalid mapping expression %s\n", @@ -1399,7 +1400,6 @@ static int expr_evaluate_map(struct eval_ctx *ctx, struct expr **expr) map->map->dtype->desc); datatype_set(map, map->mappings->set->datatype); - map->flags |= EXPR_F_CONSTANT; /* Data for range lookups needs to be in big endian order */ if (map->mappings->set->flags & NFT_SET_INTERVAL && diff --git a/src/expression.c b/src/expression.c index cb49e0b7..e5979394 100644 --- a/src/expression.c +++ b/src/expression.c @@ -1067,8 +1067,18 @@ static const struct expr_ops set_ref_expr_ops = { struct expr *set_ref_expr_alloc(const struct location *loc, struct set *set) { struct expr *expr; + const struct datatype *dtype; + unsigned int len; - expr = expr_alloc(loc, EXPR_SET_REF, set->key->dtype, 0, 0); + if (set->flags & NFT_SET_MAP) { + dtype = set->datatype; + len = set->datalen; + } else { + dtype = set->key->dtype; + len = set->key->len; + } + + expr = expr_alloc(loc, EXPR_SET_REF, dtype, 0, len); expr->set = set_get(set); expr->flags |= EXPR_F_CONSTANT; return expr; diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c index fc2574b1..b70433f0 100644 --- a/src/netlink_delinearize.c +++ b/src/netlink_delinearize.c @@ -341,6 +341,8 @@ static void netlink_parse_lookup(struct netlink_parse_ctx *ctx, if (nftnl_expr_is_set(nle, NFTNL_EXPR_LOOKUP_DREG)) { dreg = netlink_parse_register(nle, NFTNL_EXPR_LOOKUP_DREG); expr = map_expr_alloc(loc, left, right); + expr_set_type(expr, right->dtype, right->byteorder); + expr->len = right->len; if (dreg != NFT_REG_VERDICT) return netlink_set_register(ctx, dreg, expr); } else { diff --git a/src/parser_bison.y b/src/parser_bison.y index 53e66952..9b998d65 100644 --- a/src/parser_bison.y +++ b/src/parser_bison.y @@ -668,8 +668,8 @@ int nft_lex(void *, void *, void *); %type <expr> concat_expr %destructor { expr_free($$); } concat_expr -%type <expr> map_expr -%destructor { expr_free($$); } map_expr +%type <expr> map_expr map_lhs_expr +%destructor { expr_free($$); } map_expr map_lhs_expr %type <expr> verdict_map_stmt %destructor { expr_free($$); } verdict_map_stmt @@ -3378,7 +3378,11 @@ multiton_rhs_expr : prefix_rhs_expr | wildcard_expr ; -map_expr : concat_expr MAP rhs_expr +map_lhs_expr : concat_expr + | map_expr + ; + +map_expr : map_lhs_expr MAP rhs_expr { $$ = map_expr_alloc(&@$, $1, $3); } diff --git a/tests/shell/testcases/maps/dumps/left_side_map_0.nft b/tests/shell/testcases/maps/dumps/left_side_map_0.nft new file mode 100644 index 00000000..b93948fc --- /dev/null +++ b/tests/shell/testcases/maps/dumps/left_side_map_0.nft @@ -0,0 +1,10 @@ +table ip x { + map y { + type ipv4_addr : inet_service + } + + chain z { + type filter hook output priority filter; policy accept; + ip saddr map @y 22 counter packets 0 bytes 0 + } +} diff --git a/tests/shell/testcases/maps/dumps/map_to_map_0.nft b/tests/shell/testcases/maps/dumps/map_to_map_0.nft new file mode 100644 index 00000000..fd7339f9 --- /dev/null +++ b/tests/shell/testcases/maps/dumps/map_to_map_0.nft @@ -0,0 +1,14 @@ +table ip x { + map y { + type ipv4_addr : mark + } + + map yy { + type mark : inet_service + } + + chain z { + type filter hook output priority filter; policy accept; + ip saddr map @y map @yy 22 counter packets 0 bytes 0 + } +} diff --git a/tests/shell/testcases/maps/left_side_map_0 b/tests/shell/testcases/maps/left_side_map_0 new file mode 100755 index 00000000..93c721b7 --- /dev/null +++ b/tests/shell/testcases/maps/left_side_map_0 @@ -0,0 +1,8 @@ +#!/bin/bash + +set -e + +$NFT add table x +$NFT add map x y { type ipv4_addr : inet_service\; } +$NFT add chain ip x z { type filter hook output priority 0 \; } +$NFT add rule x z ip saddr map @y 22 counter diff --git a/tests/shell/testcases/maps/map_to_map_0 b/tests/shell/testcases/maps/map_to_map_0 new file mode 100755 index 00000000..95a45f62 --- /dev/null +++ b/tests/shell/testcases/maps/map_to_map_0 @@ -0,0 +1,9 @@ +#!/bin/bash + +set -e + +$NFT add table x +$NFT add map x y { type ipv4_addr : mark\; } +$NFT add map x yy { type mark : inet_service\; } +$NFT add chain ip x z { type filter hook output priority 0 \; } +$NFT add rule x z ip saddr map @y map@yy 22 counter
This change allows map expressions on the left side of comparisons: nft add rule foo bar ip saddr map @map_a == 22 counter It also allows map expressions as the left side expression of other map expressions: nft add rule foo bar ip saddr map @map_a map @map_b == 22 counter To accomplish this, some additional context needs to be set during evaluation and delinearization. A tweak is also make to the parser logic to allow map expressions as the left hand expression to other map expressions. By allowing maps as left side comparison expressions one can map information in the packet to some arbitrary piece of data and use the equality (or inequality) to make some decision about the traffic, unlike today where the result of a map lookup is only usable as the right side of a statement (like dnat or snat) that actually uses the value as input. v2: Add testcases Signed-off-by: Brett Mastbergen <bmastbergen@untangle.com> --- src/evaluate.c | 2 +- src/expression.c | 12 +++++++++++- src/netlink_delinearize.c | 2 ++ src/parser_bison.y | 10 +++++++--- .../shell/testcases/maps/dumps/left_side_map_0.nft | 10 ++++++++++ tests/shell/testcases/maps/dumps/map_to_map_0.nft | 14 ++++++++++++++ tests/shell/testcases/maps/left_side_map_0 | 8 ++++++++ tests/shell/testcases/maps/map_to_map_0 | 9 +++++++++ 8 files changed, 62 insertions(+), 5 deletions(-) create mode 100644 tests/shell/testcases/maps/dumps/left_side_map_0.nft create mode 100644 tests/shell/testcases/maps/dumps/map_to_map_0.nft create mode 100755 tests/shell/testcases/maps/left_side_map_0 create mode 100755 tests/shell/testcases/maps/map_to_map_0