audit: log nftables configuration change events

iptables, ip6tables, arptables and ebtables table registration,
replacement and unregistration configuration events are logged for the
native (legacy) iptables setsockopt api, but not for the
nftables netlink api which is used by the nft-variant of iptables in
addition to nftables itself.

Add calls to log the configuration actions in the nftables netlink api.

This uses the same NETFILTER_CFG record format but overloads the table
field.

  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.878:162) : table=?:0;?:0 family=unspecified entries=2 op=nft_register_gen pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
  ...
  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.878:162) : table=firewalld:1;?:0 family=inet entries=0 op=nft_register_table pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
  ...
  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.911:163) : table=firewalld:1;filter_FORWARD:85 family=inet entries=8 op=nft_register_chain pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
  ...
  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.911:163) : table=firewalld:1;filter_FORWARD:85 family=inet entries=101 op=nft_register_rule pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
  ...
  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.911:163) : table=firewalld:1;__set0:87 family=inet entries=87 op=nft_register_setelem pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld
  ...
  type=NETFILTER_CFG msg=audit(2020-05-28 17:46:41.911:163) : table=firewalld:1;__set0:87 family=inet entries=0 op=nft_register_set pid=396 subj=system_u:system_r:firewalld_t:s0 comm=firewalld

For further information please see issue
linux-audit/audit-kernel#124

Signed-off-by: Richard Guy Briggs <[email protected]>
Signed-off-by: Paul Moore <[email protected]>

Author: rgbriggs

include/linux/audit.h

@@ -12,6 +12,7 @@
 #include <linux/sched.h>
 #include <linux/ptrace.h>
 #include <uapi/linux/audit.h>
+#include <uapi/linux/netfilter/nf_tables.h>
 
 #define AUDIT_INO_UNSET ((unsigned long)-1)
 #define AUDIT_DEV_UNSET ((dev_t)-1)
@@ -98,6 +99,23 @@ enum audit_nfcfgop {
 	AUDIT_XT_OP_REGISTER,
 	AUDIT_XT_OP_REPLACE,
 	AUDIT_XT_OP_UNREGISTER,
+	AUDIT_NFT_OP_TABLE_REGISTER,
+	AUDIT_NFT_OP_TABLE_UNREGISTER,
+	AUDIT_NFT_OP_CHAIN_REGISTER,
+	AUDIT_NFT_OP_CHAIN_UNREGISTER,
+	AUDIT_NFT_OP_RULE_REGISTER,
+	AUDIT_NFT_OP_RULE_UNREGISTER,
+	AUDIT_NFT_OP_SET_REGISTER,
+	AUDIT_NFT_OP_SET_UNREGISTER,
+	AUDIT_NFT_OP_SETELEM_REGISTER,
+	AUDIT_NFT_OP_SETELEM_UNREGISTER,
+	AUDIT_NFT_OP_GEN_REGISTER,
+	AUDIT_NFT_OP_OBJ_REGISTER,
+	AUDIT_NFT_OP_OBJ_UNREGISTER,
+	AUDIT_NFT_OP_OBJ_RESET,
+	AUDIT_NFT_OP_FLOWTABLE_REGISTER,
+	AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
+	AUDIT_NFT_OP_INVALID,
 };
 
 extern int is_audit_feature_set(int which);

kernel/auditsc.c

@@ -75,6 +75,7 @@
 #include <linux/uaccess.h>
 #include <linux/fsnotify_backend.h>
 #include <uapi/linux/limits.h>
+#include <uapi/linux/netfilter/nf_tables.h>
 
 #include "audit.h"
 
@@ -136,9 +137,26 @@ struct audit_nfcfgop_tab {
 };
 
 static const struct audit_nfcfgop_tab audit_nfcfgs[] = {
-	{ AUDIT_XT_OP_REGISTER,		"register"	},
-	{ AUDIT_XT_OP_REPLACE,		"replace"	},
-	{ AUDIT_XT_OP_UNREGISTER,	"unregister"	},
+	{ AUDIT_XT_OP_REGISTER,			"xt_register"		   },
+	{ AUDIT_XT_OP_REPLACE,			"xt_replace"		   },
+	{ AUDIT_XT_OP_UNREGISTER,		"xt_unregister"		   },
+	{ AUDIT_NFT_OP_TABLE_REGISTER,		"nft_register_table"	   },
+	{ AUDIT_NFT_OP_TABLE_UNREGISTER,	"nft_unregister_table"	   },
+	{ AUDIT_NFT_OP_CHAIN_REGISTER,		"nft_register_chain"	   },
+	{ AUDIT_NFT_OP_CHAIN_UNREGISTER,	"nft_unregister_chain"	   },
+	{ AUDIT_NFT_OP_RULE_REGISTER,		"nft_register_rule"	   },
+	{ AUDIT_NFT_OP_RULE_UNREGISTER,		"nft_unregister_rule"	   },
+	{ AUDIT_NFT_OP_SET_REGISTER,		"nft_register_set"	   },
+	{ AUDIT_NFT_OP_SET_UNREGISTER,		"nft_unregister_set"	   },
+	{ AUDIT_NFT_OP_SETELEM_REGISTER,	"nft_register_setelem"	   },
+	{ AUDIT_NFT_OP_SETELEM_UNREGISTER,	"nft_unregister_setelem"   },
+	{ AUDIT_NFT_OP_GEN_REGISTER,		"nft_register_gen"	   },
+	{ AUDIT_NFT_OP_OBJ_REGISTER,		"nft_register_obj"	   },
+	{ AUDIT_NFT_OP_OBJ_UNREGISTER,		"nft_unregister_obj"	   },
+	{ AUDIT_NFT_OP_OBJ_RESET,		"nft_reset_obj"		   },
+	{ AUDIT_NFT_OP_FLOWTABLE_REGISTER,	"nft_register_flowtable"   },
+	{ AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,	"nft_unregister_flowtable" },
+	{ AUDIT_NFT_OP_INVALID,			"nft_invalid"		   },
 };
 
 static int audit_match_perm(struct audit_context *ctx, int mask)

net/netfilter/nf_tables_api.c

@@ -12,6 +12,7 @@
 #include <linux/netlink.h>
 #include <linux/vmalloc.h>
 #include <linux/rhashtable.h>
+#include <linux/audit.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nf_tables.h>
@@ -693,6 +694,16 @@ static void nf_tables_table_notify(const struct nft_ctx *ctx, int event)
 {
 	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);
+	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -1428,6 +1439,17 @@ static void nf_tables_chain_notify(const struct nft_ctx *ctx, int event)
 {
 	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);
+	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -2693,6 +2715,17 @@ static void nf_tables_rule_notify(const struct nft_ctx *ctx,
 {
 	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);
+	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -3695,6 +3728,17 @@ static void nf_tables_set_notify(const struct nft_ctx *ctx,
 	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);
+	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -4811,6 +4855,17 @@ static void nf_tables_setelem_notify(const struct nft_ctx *ctx,
 	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);
+	kfree(buf);
 
 	if (!ctx->report && !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
 		return;
@@ -5892,6 +5947,19 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 			    obj->ops->type->type != filter->type)
 				goto cont;
 
+			if (reset) {
+				char *buf = kasprintf(GFP_KERNEL,
+						      "%s:%llu;?:0",
+						      table->name,
+						      table->handle);
+
+				audit_log_nfcfg(buf,
+						family,
+						obj->handle,
+						AUDIT_NFT_OP_OBJ_RESET);
+				kfree(buf);
+			}
+
 			if (nf_tables_fill_obj_info(skb, net, NETLINK_CB(cb->skb).portid,
 						    cb->nlh->nlmsg_seq,
 						    NFT_MSG_NEWOBJ,
@@ -6002,6 +6070,17 @@ static int nf_tables_getobj(struct net *net, struct sock *nlsk,
 	if (NFNL_MSG_TYPE(nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET)
 		reset = true;
 
+	if (reset) {
+		char *buf = kasprintf(GFP_KERNEL, "%s:%llu;?:0",
+				      table->name, table->handle);
+
+		audit_log_nfcfg(buf,
+				family,
+				obj->handle,
+				AUDIT_NFT_OP_OBJ_RESET);
+		kfree(buf);
+	}
+
 	err = nf_tables_fill_obj_info(skb2, net, NETLINK_CB(skb).portid,
 				      nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0,
 				      family, table, obj, reset);
@@ -6077,6 +6156,16 @@ void nft_obj_notify(struct net *net, const struct nft_table *table,
 {
 	struct sk_buff *skb;
 	int err;
+	char *buf = kasprintf(GFP_KERNEL, "%s:%llu;?:0",
+			      table->name, table->handle);
+
+	audit_log_nfcfg(buf,
+			family,
+			obj->handle,
+			event == NFT_MSG_NEWOBJ ?
+				AUDIT_NFT_OP_OBJ_REGISTER :
+				AUDIT_NFT_OP_OBJ_UNREGISTER);
+	kfree(buf);
 
 	if (!report &&
 	    !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
@@ -6856,6 +6945,17 @@ static void nf_tables_flowtable_notify(struct nft_ctx *ctx,
 {
 	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);
+	kfree(buf);
 
 	if (ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -6977,6 +7077,9 @@ static void nf_tables_gen_notify(struct net *net, struct sk_buff *skb,
 	struct sk_buff *skb2;
 	int err;
 
+	audit_log_nfcfg("?:0;?:0", 0, net->nft.base_seq,
+			AUDIT_NFT_OP_GEN_REGISTER);
+
 	if (nlmsg_report(nlh) &&
 	    !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
 		return;