netfilter: nf_tables: don't store chain address on jump

Now that the rule trailer/end marker and the rcu head reside in the
same structure, we no longer need to save/restore the chain pointer
when performing/returning from a jump.

We can simply let the trace infra walk the evaluated rule until it
hits the end marker and then fetch the chain pointer from there.

When the rule is NULL (policy tracing), then chain and basechain
pointers were already identical, so just use the basechain.

This cuts size of jumpstack in half, from 256 to 128 bytes in 64bit,
scripts/stackusage says:

nf_tables_core.c:251 nft_do_chain    328     static

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 1b8e305bb54aec82f71a79755ae166ed64387838..f476fd030626de355bc55f7864a0c918141274be 100644 (file)
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1046,6 +1046,18 @@ struct nft_rule_dp {
                __attribute__((aligned(__alignof__(struct nft_expr))));
 };
 
+struct nft_rule_dp_last {
+       struct nft_rule_dp end;         /* end of nft_rule_blob marker */
+       struct rcu_head h;              /* call_rcu head */
+       struct nft_rule_blob *blob;     /* ptr to free via call_rcu */
+       const struct nft_chain *chain;  /* for nftables tracing */
+};
+
+static inline const struct nft_rule_dp *nft_rule_next(const struct nft_rule_dp *rule)
+{
+       return (void *)rule + sizeof(*rule) + rule->dlen;
+}
+
 struct nft_rule_blob {
        unsigned long                   size;
        unsigned char                   data[]
@@ -1396,7 +1408,6 @@ void nft_unregister_flowtable_type(struct nf_flowtable_type *type);
  *     @packet_dumped: packet headers sent in a previous traceinfo message
  *     @pkt: pktinfo currently processed
  *     @basechain: base chain currently processed
- *     @chain: chain currently processed
  *     @rule:  rule that was evaluated
  *     @verdict: verdict given by rule
  */
@@ -1408,7 +1419,6 @@ struct nft_traceinfo {
        u32                             skbid;
        const struct nft_pktinfo        *pkt;
        const struct nft_base_chain     *basechain;
-       const struct nft_chain          *chain;
        const struct nft_rule_dp        *rule;
        const struct nft_verdict        *verdict;
 };

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 79848a27e640d033512bb7b1bb1f1b9743926cd2..0e1c86bb51a2c193d43f4b920aed91f9a0b77f3a 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2110,13 +2110,6 @@ static void nft_chain_release_hook(struct nft_chain_hook *hook)
        module_put(hook->type->owner);
 }
 
-struct nft_rule_dp_last {
-       struct nft_rule_dp end; /* end of nft_rule_blob marker */
-       struct rcu_head h;
-       struct nft_rule_blob *blob;
-       const struct nft_chain *chain;  /* for tracing */
-};
-
 static void nft_last_rule(const struct nft_chain *chain, const void *ptr)
 {
        struct nft_rule_dp_last *lrule;

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index ec3bab75109289bc5e651a5dc9c6f449d8766d06..89c05b64c2a25e96a8f420fd58c895139196a283 100644 (file)
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -42,13 +42,11 @@ static inline void nf_skip_indirect_calls_enable(void) { }
 #endif
 
 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
-                                       const struct nft_chain *chain,
                                        enum nft_trace_types type)
 {
        if (!info->trace || !info->nf_trace)
                return;
 
-       info->chain = chain;
        info->type = type;
 
        nft_trace_notify(info);
@@ -56,14 +54,13 @@ static noinline void __nft_trace_packet(struct nft_traceinfo *info,
 
 static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
                                    struct nft_traceinfo *info,
-                                   const struct nft_chain *chain,
                                    const struct nft_rule_dp *rule,
                                    enum nft_trace_types type)
 {
        if (static_branch_unlikely(&nft_trace_enabled)) {
                info->nf_trace = pkt->skb->nf_trace;
                info->rule = rule;
-               __nft_trace_packet(info, chain, type);
+               __nft_trace_packet(info, type);
        }
 }
 
@@ -111,7 +108,6 @@ static void nft_cmp16_fast_eval(const struct nft_expr *expr,
 }
 
 static noinline void __nft_trace_verdict(struct nft_traceinfo *info,
-                                        const struct nft_chain *chain,
                                         const struct nft_regs *regs)
 {
        enum nft_trace_types type;
@@ -133,17 +129,16 @@ static noinline void __nft_trace_verdict(struct nft_traceinfo *info,
                break;
        }
 
-       __nft_trace_packet(info, chain, type);
+       __nft_trace_packet(info, type);
 }
 
 static inline void nft_trace_verdict(struct nft_traceinfo *info,
-                                    const struct nft_chain *chain,
                                     const struct nft_rule_dp *rule,
                                     const struct nft_regs *regs)
 {
        if (static_branch_unlikely(&nft_trace_enabled)) {
                info->rule = rule;
-               __nft_trace_verdict(info, chain, regs);
+               __nft_trace_verdict(info, regs);
        }
 }
 
@@ -203,7 +198,6 @@ static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 }
 
 struct nft_jumpstack {
-       const struct nft_chain *chain;
        const struct nft_rule_dp *rule;
 };
 
@@ -247,7 +241,6 @@ indirect_call:
 #define nft_rule_expr_first(rule)      (struct nft_expr *)&rule->data[0]
 #define nft_rule_expr_next(expr)       ((void *)expr) + expr->ops->size
 #define nft_rule_expr_last(rule)       (struct nft_expr *)&rule->data[rule->dlen]
-#define nft_rule_next(rule)            (void *)rule + sizeof(*rule) + rule->dlen
 
 #define nft_rule_dp_for_each_expr(expr, last, rule) \
         for ((expr) = nft_rule_expr_first(rule), (last) = nft_rule_expr_last(rule); \
@@ -302,14 +295,14 @@ next_rule:
                        nft_trace_copy_nftrace(pkt, &info);
                        continue;
                case NFT_CONTINUE:
-                       nft_trace_packet(pkt, &info, chain, rule,
+                       nft_trace_packet(pkt, &info, rule,
                                         NFT_TRACETYPE_RULE);
                        continue;
                }
                break;
        }
 
-       nft_trace_verdict(&info, chain, rule, &regs);
+       nft_trace_verdict(&info, rule, &regs);
 
        switch (regs.verdict.code & NF_VERDICT_MASK) {
        case NF_ACCEPT:
@@ -323,7 +316,6 @@ next_rule:
        case NFT_JUMP:
                if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
                        return NF_DROP;
-               jumpstack[stackptr].chain = chain;
                jumpstack[stackptr].rule = nft_rule_next(rule);
                stackptr++;
                fallthrough;
@@ -339,12 +331,11 @@ next_rule:
 
        if (stackptr > 0) {
                stackptr--;
-               chain = jumpstack[stackptr].chain;
                rule = jumpstack[stackptr].rule;
                goto next_rule;
        }
 
-       nft_trace_packet(pkt, &info, basechain, NULL, NFT_TRACETYPE_POLICY);
+       nft_trace_packet(pkt, &info, NULL, NFT_TRACETYPE_POLICY);
 
        if (static_branch_unlikely(&nft_counters_enabled))
                nft_update_chain_stats(basechain, pkt);

diff --git a/net/netfilter/nf_tables_trace.c b/net/netfilter/nf_tables_trace.c
index 1163ba9c140119771f4ff7b120d60bf266d20c86..3d9b83d84a8422c156ab811449e902e345f42edb 100644 (file)
--- a/net/netfilter/nf_tables_trace.c
+++ b/net/netfilter/nf_tables_trace.c
@@ -164,9 +164,29 @@ static bool nft_trace_have_verdict_chain(struct nft_traceinfo *info)
        return true;
 }
 
+static const struct nft_chain *nft_trace_get_chain(const struct nft_traceinfo *info)
+{
+       const struct nft_rule_dp *rule = info->rule;
+       const struct nft_rule_dp_last *last;
+
+       if (!rule)
+               return &info->basechain->chain;
+
+       while (!rule->is_last)
+               rule = nft_rule_next(rule);
+
+       last = (const struct nft_rule_dp_last *)rule;
+
+       if (WARN_ON_ONCE(!last->chain))
+               return &info->basechain->chain;
+
+       return last->chain;
+}
+
 void nft_trace_notify(struct nft_traceinfo *info)
 {
        const struct nft_pktinfo *pkt = info->pkt;
+       const struct nft_chain *chain;
        struct nlmsghdr *nlh;
        struct sk_buff *skb;
        unsigned int size;
@@ -176,9 +196,11 @@ void nft_trace_notify(struct nft_traceinfo *info)
        if (!nfnetlink_has_listeners(nft_net(pkt), NFNLGRP_NFTRACE))
                return;
 
+       chain = nft_trace_get_chain(info);
+
        size = nlmsg_total_size(sizeof(struct nfgenmsg)) +
-               nla_total_size(strlen(info->chain->table->name)) +
-               nla_total_size(strlen(info->chain->name)) +
+               nla_total_size(strlen(chain->table->name)) +
+               nla_total_size(strlen(chain->name)) +
                nla_total_size_64bit(sizeof(__be64)) +  /* rule handle */
                nla_total_size(sizeof(__be32)) +        /* trace type */
                nla_total_size(0) +                     /* VERDICT, nested */
@@ -217,10 +239,10 @@ void nft_trace_notify(struct nft_traceinfo *info)
        if (nla_put_u32(skb, NFTA_TRACE_ID, info->skbid))
                goto nla_put_failure;
 
-       if (nla_put_string(skb, NFTA_TRACE_CHAIN, info->chain->name))
+       if (nla_put_string(skb, NFTA_TRACE_CHAIN, chain->name))
                goto nla_put_failure;
 
-       if (nla_put_string(skb, NFTA_TRACE_TABLE, info->chain->table->name))
+       if (nla_put_string(skb, NFTA_TRACE_TABLE, chain->table->name))
                goto nla_put_failure;
 
        if (nf_trace_fill_rule_info(skb, info))