netlink_linearize: use NFT_REG32 values internally

Prepare netlink_linearize for 32 bit register usage:

Switch to use 16 data registers of 32 bit each. A helper function takes
care of mapping the registers to the NFT_REG32 values and, if the
register refers to the beginning of an 128 bit area, the old NFT_REG_1-4
values for compatibility.

New register reservation and release helper function take the size into
account and reserve the required amount of registers.

The reservation and release functions will so far still always allocate
128 bit. If no other expression in a rule uses a 32 bit register directly,
these will be mapped to the old register values, meaning everything
continues to work with old kernel versions.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 39 insertions, 4 deletions

diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index beeb0c22..6930b39d 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -27,21 +27,54 @@ struct netlink_linearize_ctx {
 static void netlink_put_register(struct nft_rule_expr *nle,
 				 uint32_t attr, uint32_t reg)
 {
+	/* Convert to 128 bit register numbers if possible for compatibility */
+	if (reg != NFT_REG_VERDICT) {
+		reg -= NFT_REG_1;
+		if (reg % (NFT_REG_SIZE / NFT_REG32_SIZE) == 0)
+			reg = NFT_REG_1 + reg / (NFT_REG_SIZE / NFT_REG32_SIZE);
+		else
+			reg += NFT_REG32_00;
+	}
+
 	nft_rule_expr_set_u32(nle, attr, reg);
 }
 
+static enum nft_registers __get_register(struct netlink_linearize_ctx *ctx,
+					 unsigned int size)
+{
+	unsigned int reg, n;
+
+	n = netlink_register_space(size);
+	if (ctx->reg_low + n > NFT_REG_1 + NFT_REG32_15 - NFT_REG32_00 + 1)
+		BUG("register reg_low %u invalid\n", ctx->reg_low);
+
+	reg = ctx->reg_low;
+	ctx->reg_low += n;
+	return reg;
+}
+
+static void __release_register(struct netlink_linearize_ctx *ctx,
+			       unsigned int size)
+{
+	unsigned int n;
+
+	n = netlink_register_space(size);
+	if (ctx->reg_low < NFT_REG_1 + n)
+		BUG("register reg_low %u invalid\n", ctx->reg_low);
+
+	ctx->reg_low -= n;
+}
+
 static enum nft_registers get_register(struct netlink_linearize_ctx *ctx,
 				       const struct expr *expr)
 {
-	if (ctx->reg_low > NFT_REG_MAX)
-		BUG("register reg_low %u invalid\n", ctx->reg_low);
-	return ctx->reg_low++;
+	return __get_register(ctx, NFT_REG_SIZE * BITS_PER_BYTE);
 }
 
 static void release_register(struct netlink_linearize_ctx *ctx,
 			     const struct expr *expr)
 {
-	ctx->reg_low--;
+	__release_register(ctx, NFT_REG_SIZE * BITS_PER_BYTE);
 }
 
 static void netlink_gen_expr(struct netlink_linearize_ctx *ctx,
@@ -509,6 +542,8 @@ static void netlink_gen_expr(struct netlink_linearize_ctx *ctx,
 			     const struct expr *expr,
 			     enum nft_registers dreg)
 {
+	assert(dreg < ctx->reg_low);
+
 	switch (expr->ops->type) {
 	case EXPR_VERDICT:
 	case EXPR_VALUE: