Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 4 Jun 2020 13:57:56 -0400
From:   Richard Guy Briggs <rgb@redhat.com>
To:     Steve Grubb <sgrubb@redhat.com>
Cc:     Linux-Audit Mailing List <linux-audit@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netfilter-devel@vger.kernel.org, Paul Moore <paul@paul-moore.com>,
        omosnace@redhat.com, fw@strlen.de, twoerner@redhat.com,
        eparis@parisplace.org, tgraf@infradead.org
Subject: Re: [PATCH ghak124 v3] audit: log nftables configuration change
 events
Message-ID: <20200604175756.d3x5fy4k4urilgbp@madcap2.tricolour.ca>
References: <f9da8b5dbf2396b621c77c17b5b1123be5aa484e.1591275439.git.rgb@redhat.com>
 <530434533.t1QJnzVmUA@x2>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <530434533.t1QJnzVmUA@x2>
User-Agent: NeoMutt/20180716
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2020-06-04 13:03, Steve Grubb wrote:
> On Thursday, June 4, 2020 9:20:49 AM EDT Richard Guy Briggs wrote:
> > 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
> > https://github.com/linux-audit/audit-kernel/issues/124
> > 
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> > Changelog:
> > v3:
> > - inline message type rather than table
> > 
> > v2:
> > - differentiate between xtables and nftables
> > - add set, setelem, obj, flowtable, gen
> > - use nentries field as appropriate per type
> > - overload the "tables" field with table handle and chain/set/flowtable
> > 
> >  include/linux/audit.h         |  18 ++++++++
> >  kernel/auditsc.c              |  24 ++++++++--
> >  net/netfilter/nf_tables_api.c | 103
> > ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 142
> > insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 3fcd9ee49734..604ede630580 100644
> > --- a/include/linux/audit.h
> > +++ b/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);
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index 468a23390457..3a9100e95fda 100644
> > --- a/kernel/auditsc.c
> > +++ b/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"		   
> },
> >  };
> 
> I still don't like the event format because it doesn't give complete subject 
> information. However, I thought I'd comment on this string table. Usually 
> it's sufficient to log the number and then have the string table in user space 
> which looks it up during interpretation.

That is a good idea that would help reduce kernel cycles and netlink
bandwidth, but the format was set in 2011 so it is a bit late to change
that now:
	fbabf31e4d48 ("netfilter: create audit records for x_tables replaces")

> -Steve
> 
> >  static int audit_match_perm(struct audit_context *ctx, int mask)
> > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> > index 3558e76e2733..b9e7440cc87d 100644
> > --- a/net/netfilter/nf_tables_api.c
> > +++ b/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))
> > @@ -2691,6 +2713,17 @@ 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))
> > @@ -3693,6 +3726,17 @@ 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))
> > @@ -4809,6 +4853,17 @@ 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;
> > @@ -5890,6 +5945,19 @@ 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,
> > @@ -6000,6 +6068,17 @@ 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);
> > @@ -6075,6 +6154,16 @@ 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))
> > @@ -6701,6 +6790,17 @@ 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))
> > @@ -6822,6 +6922,9 @@ 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;
> 
> 
> 
> 

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635