proto: track full stack of seen l2 protocols, not just cumulative offset

For input, a cumulative size counter of all pushed l2 headers is enough,
because we have the full expression tree available to us.

For delinearization we need to track all seen l2 headers, else we lose
information that we might need at a later time.

Consider:

rule netdev nt nc set update ether saddr . vlan id

during delinearization, the vlan proto_desc replaces the ethernet one,
and by the time we try to split the concatenation apart we will search
the ether saddr offset vs. the templates for proto_vlan.

This replaces the offset with an array that stores the protocol
descriptions seen.

Then, if the payload offset is larger than our description, search the
l2 stack and adjust the offset until we're within the expected offset
boundary.

Reported-by: Eric Garver <eric@garver.life>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 0 insertions, 5 deletions

diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 42221f8c..8851043b 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -1977,11 +1977,6 @@ static void payload_match_postprocess(struct rule_pp_ctx *ctx,
 				      struct expr *expr,
 				      struct expr *payload)
 {
-	enum proto_bases base = payload->payload.base;
-
-	assert(payload->payload.offset >= ctx->pctx.protocol[base].offset);
-	payload->payload.offset -= ctx->pctx.protocol[base].offset;
-
 	switch (expr->op) {
 	case OP_EQ:
 	case OP_NEQ: