audit: log nftables configuration change events once per table

Reduce logging of nftables events to a level similar to iptables.
Restore the table field to list the table, adding the generation.

Indicate the op as the most significant operation in the event.

A couple of sample events:

type=PROCTITLE msg=audit(2021-03-18 09:30:49.801:143) : proctitle=/usr/bin/python3 -s /usr/sbin/firewalld --nofork --nopid
type=SYSCALL msg=audit(2021-03-18 09:30:49.801:143) : arch=x86_64 syscall=sendmsg success=yes exit=172 a0=0x6 a1=0x7ffdcfcbe650 a2=0x0 a3=0x7ffdcfcbd52c items=0 ppid=1 pid=367 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=roo
t sgid=root fsgid=root tty=(none) ses=unset comm=firewalld exe=/usr/bin/python3.9 subj=system_u:system_r:firewalld_t:s0 key=(null)
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.801:143) : table=firewalld:2 family=ipv6 entries=1 op=nft_register_table pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.801:143) : table=firewalld:2 family=ipv4 entries=1 op=nft_register_table pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.801:143) : table=firewalld:2 family=inet entries=1 op=nft_register_table pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld

type=PROCTITLE msg=audit(2021-03-18 09:30:49.839:144) : proctitle=/usr/bin/python3 -s /usr/sbin/firewalld --nofork --nopid
type=SYSCALL msg=audit(2021-03-18 09:30:49.839:144) : arch=x86_64 syscall=sendmsg success=yes exit=22792 a0=0x6 a1=0x7ffdcfcbe650 a2=0x0 a3=0x7ffdcfcbd52c items=0 ppid=1 pid=367 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=r
oot sgid=root fsgid=root tty=(none) ses=unset comm=firewalld exe=/usr/bin/python3.9 subj=system_u:system_r:firewalld_t:s0 key=(null)
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.839:144) : table=firewalld:3 family=ipv6 entries=30 op=nft_register_chain pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.839:144) : table=firewalld:3 family=ipv4 entries=30 op=nft_register_chain pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
type=NETFILTER_CFG msg=audit(2021-03-18 09:30:49.839:144) : table=firewalld:3 family=inet entries=165 op=nft_register_chain pid=367 subj=system_u:system_r:firewalld_t:s0 comm=firewalld

The issue was originally documented in
https://github.com/linux-audit/audit-kernel/issues/124

Signed-off-by: Richard Guy Briggs <[e-mail]>
Acked-by: Paul Moore <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nf_tables_api.c

···
 	.automatic_shrinking	= true,
 };
 
+struct nft_audit_data {
+	struct nft_table *table;
+	int entries;
+	int op;
+	struct list_head list;
+};
+
+static const u8 nft2audit_op[NFT_MSG_MAX] = { // enum nf_tables_msg_types
+	[NFT_MSG_NEWTABLE]	= AUDIT_NFT_OP_TABLE_REGISTER,
+	[NFT_MSG_GETTABLE]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELTABLE]	= AUDIT_NFT_OP_TABLE_UNREGISTER,
+	[NFT_MSG_NEWCHAIN]	= AUDIT_NFT_OP_CHAIN_REGISTER,
+	[NFT_MSG_GETCHAIN]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELCHAIN]	= AUDIT_NFT_OP_CHAIN_UNREGISTER,
+	[NFT_MSG_NEWRULE]	= AUDIT_NFT_OP_RULE_REGISTER,
+	[NFT_MSG_GETRULE]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELRULE]	= AUDIT_NFT_OP_RULE_UNREGISTER,
+	[NFT_MSG_NEWSET]	= AUDIT_NFT_OP_SET_REGISTER,
+	[NFT_MSG_GETSET]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELSET]	= AUDIT_NFT_OP_SET_UNREGISTER,
+	[NFT_MSG_NEWSETELEM]	= AUDIT_NFT_OP_SETELEM_REGISTER,
+	[NFT_MSG_GETSETELEM]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELSETELEM]	= AUDIT_NFT_OP_SETELEM_UNREGISTER,
+	[NFT_MSG_NEWGEN]	= AUDIT_NFT_OP_GEN_REGISTER,
+	[NFT_MSG_GETGEN]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_TRACE]		= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_NEWOBJ]	= AUDIT_NFT_OP_OBJ_REGISTER,
+	[NFT_MSG_GETOBJ]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELOBJ]	= AUDIT_NFT_OP_OBJ_UNREGISTER,
+	[NFT_MSG_GETOBJ_RESET]	= AUDIT_NFT_OP_OBJ_RESET,
+	[NFT_MSG_NEWFLOWTABLE]	= AUDIT_NFT_OP_FLOWTABLE_REGISTER,
+	[NFT_MSG_GETFLOWTABLE]	= AUDIT_NFT_OP_INVALID,
+	[NFT_MSG_DELFLOWTABLE]	= AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
+};
+
 static void nft_validate_state_update(struct net *net, u8 new_validate_state)
 {
 	switch (net->nft.validate_state) {
···
 {
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;?:0",
-			      ctx->table->name, ctx->table->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			ctx->table->use,
-			event == NFT_MSG_NEWTABLE ?
-				AUDIT_NFT_OP_TABLE_REGISTER :
-				AUDIT_NFT_OP_TABLE_UNREGISTER,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
···
 {
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
-			      ctx->table->name, ctx->table->handle,
-			      ctx->chain->name, ctx->chain->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			ctx->chain->use,
-			event == NFT_MSG_NEWCHAIN ?
-				AUDIT_NFT_OP_CHAIN_REGISTER :
-				AUDIT_NFT_OP_CHAIN_UNREGISTER,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
···
 {
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
-			      ctx->table->name, ctx->table->handle,
-			      ctx->chain->name, ctx->chain->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			rule->handle,
-			event == NFT_MSG_NEWRULE ?
-				AUDIT_NFT_OP_RULE_REGISTER :
-				AUDIT_NFT_OP_RULE_UNREGISTER,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
···
 	struct sk_buff *skb;
 	u32 portid = ctx->portid;
 	int err;
-	char *buf = kasprintf(gfp_flags, "%s:%llu;%s:%llu",
-			      ctx->table->name, ctx->table->handle,
-			      set->name, set->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			set->field_count,
-			event == NFT_MSG_NEWSET ?
-				AUDIT_NFT_OP_SET_REGISTER :
-				AUDIT_NFT_OP_SET_UNREGISTER,
-			gfp_flags);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
···
 	u32 portid = ctx->portid;
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
-			      ctx->table->name, ctx->table->handle,
-			      set->name, set->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			set->handle,
-			event == NFT_MSG_NEWSETELEM ?
-				AUDIT_NFT_OP_SETELEM_REGISTER :
-				AUDIT_NFT_OP_SETELEM_UNREGISTER,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report && !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
 		return;
···
 			    filter->type != NFT_OBJECT_UNSPEC &&
 			    obj->ops->type->type != filter->type)
 				goto cont;
-
 			if (reset) {
 				char *buf = kasprintf(GFP_ATOMIC,
-						      "%s:%llu;?:0",
+						      "%s:%u",
 						      table->name,
-						      table->handle);
+						      net->nft.base_seq);
 
 				audit_log_nfcfg(buf,
 						family,
···
 		reset = true;
 
 	if (reset) {
-		char *buf = kasprintf(GFP_ATOMIC, "%s:%llu;?:0",
-				      table->name, table->handle);
+		char *buf = kasprintf(GFP_ATOMIC, "%s:%u",
+				      table->name, net->nft.base_seq);
 
 		audit_log_nfcfg(buf,
 				family,
···
 {
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(gfp, "%s:%llu;?:0",
-			      table->name, table->handle);
+	char *buf = kasprintf(gfp, "%s:%u",
+			      table->name, net->nft.base_seq);
 
 	audit_log_nfcfg(buf,
 			family,
 			obj->handle,
 			event == NFT_MSG_NEWOBJ ?
-				AUDIT_NFT_OP_OBJ_REGISTER :
-				AUDIT_NFT_OP_OBJ_UNREGISTER,
+				 AUDIT_NFT_OP_OBJ_REGISTER :
+				 AUDIT_NFT_OP_OBJ_UNREGISTER,
 			gfp);
 	kfree(buf);
 
···
 {
 	struct sk_buff *skb;
 	int err;
-	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
-			      flowtable->table->name, flowtable->table->handle,
-			      flowtable->name, flowtable->handle);
-
-	audit_log_nfcfg(buf,
-			ctx->family,
-			flowtable->hooknum,
-			event == NFT_MSG_NEWFLOWTABLE ?
-				AUDIT_NFT_OP_FLOWTABLE_REGISTER :
-				AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
···
 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 	struct sk_buff *skb2;
 	int err;
-
-	audit_log_nfcfg("?:0;?:0", 0, net->nft.base_seq,
-			AUDIT_NFT_OP_GEN_REGISTER, GFP_KERNEL);
 
 	if (!nlmsg_report(nlh) &&
 	    !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
···
 	WARN_ON_ONCE(!list_empty(&net->nft.notify_list));
 }
 
+static int nf_tables_commit_audit_alloc(struct list_head *adl,
+					struct nft_table *table)
+{
+	struct nft_audit_data *adp;
+
+	list_for_each_entry(adp, adl, list) {
+		if (adp->table == table)
+			return 0;
+	}
+	adp = kzalloc(sizeof(*adp), GFP_KERNEL);
+	if (!adp)
+		return -ENOMEM;
+	adp->table = table;
+	list_add(&adp->list, adl);
+	return 0;
+}
+
+static void nf_tables_commit_audit_collect(struct list_head *adl,
+					   struct nft_table *table, u32 op)
+{
+	struct nft_audit_data *adp;
+
+	list_for_each_entry(adp, adl, list) {
+		if (adp->table == table)
+			goto found;
+	}
+	WARN_ONCE("table=%s not expected in commit list", table->name);
+	return;
+found:
+	adp->entries++;
+	if (!adp->op || adp->op > op)
+		adp->op = op;
+}
+
+#define AUNFTABLENAMELEN (NFT_TABLE_MAXNAMELEN + 22)
+
+static void nf_tables_commit_audit_log(struct list_head *adl, u32 generation)
+{
+	struct nft_audit_data *adp, *adn;
+	char aubuf[AUNFTABLENAMELEN];
+
+	list_for_each_entry_safe(adp, adn, adl, list) {
+		snprintf(aubuf, AUNFTABLENAMELEN, "%s:%u", adp->table->name,
+			 generation);
+		audit_log_nfcfg(aubuf, adp->table->family, adp->entries,
+				nft2audit_op[adp->op], GFP_KERNEL);
+		list_del(&adp->list);
+		kfree(adp);
+	}
+}
+
 static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 {
 	struct nft_trans *trans, *next;
 	struct nft_trans_elem *te;
 	struct nft_chain *chain;
 	struct nft_table *table;
+	LIST_HEAD(adl);
 	int err;
 
 	if (list_empty(&net->nft.commit_list)) {
···
 	list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
 		int ret;
 
+		ret = nf_tables_commit_audit_alloc(&adl, trans->ctx.table);
+		if (ret) {
+			nf_tables_commit_chain_prepare_cancel(net);
+			return ret;
+		}
 		if (trans->msg_type == NFT_MSG_NEWRULE ||
 		    trans->msg_type == NFT_MSG_DELRULE) {
 			chain = trans->ctx.chain;
···
 	net->nft.gencursor = nft_gencursor_next(net);
 
 	list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
+		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
+					       trans->msg_type);
 		switch (trans->msg_type) {
 		case NFT_MSG_NEWTABLE:
 			if (nft_trans_table_update(trans)) {
···
 
 	nft_commit_notify(net, NETLINK_CB(skb).portid);
 	nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
+	nf_tables_commit_audit_log(&adl, net->nft.base_seq);
 	nf_tables_commit_release(net);
 
 	return 0;