[PATCH v5] audit: log nftables configuration change events once per table

[PATCH v5] audit: log nftables configuration change events once per table

[Richard Guy Briggs]

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 <rgb@redhat.com>
---
Changelog:
v5:
(sorry for all the noise...)
- fix kbuild missing prototype warning in nf_tables_commit_audit_{alloc,collect,log}() <lkp@intel.com>

v4:
- move nf_tables_commit_audit_log() before nf_tables_commit_release() [fw]
- move nft2audit_op[] from audit.h to nf_tables_api.c

v3:
- fix function braces, reduce parameter scope [pna]
- pre-allocate nft_audit_data per table in step 1, bail on ENOMEM [pna]

v2:
- convert NFT ops to array indicies in nft2audit_op[] [ps]
- use linux lists [pna]
- use functions for each of collection and logging of audit data [pna]
---
 net/netfilter/nf_tables_api.c | 187 +++++++++++++++++++---------------
 1 file changed, 104 insertions(+), 83 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index c1eb5cdb3033..ef51abe3a6d7 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -66,6 +66,41 @@ static const struct rhashtable_params nft_objname_ht_params = {
 	.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) {
@@ -717,17 +752,6 @@ 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,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -1491,18 +1515,6 @@ 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,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -2855,18 +2867,6 @@ 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,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -3901,18 +3901,6 @@ 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,
-			gfp_flags);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -5097,18 +5085,6 @@ 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,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report && !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
 		return;
@@ -6310,12 +6286,11 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 			    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,
@@ -6436,8 +6411,8 @@ static int nf_tables_getobj(struct net *net, struct sock *nlsk,
 		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,
@@ -6525,15 +6500,15 @@ void nft_obj_notify(struct net *net, const struct nft_table *table,
 {
 	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);
 
@@ -7333,18 +7308,6 @@ 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,
-			GFP_KERNEL);
-	kfree(buf);
 
 	if (!ctx->report &&
 	    !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
@@ -7465,9 +7428,6 @@ 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, GFP_KERNEL);
-
 	if (!nlmsg_report(nlh) &&
 	    !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
 		return;
@@ -8006,12 +7966,65 @@ static void nft_commit_notify(struct net *net, u32 portid)
 	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;
+	INIT_LIST_HEAD(&adp->list);
+	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)) {
@@ -8031,6 +8044,11 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 	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;
@@ -8206,10 +8224,13 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 			}
 			break;
 		}
+		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
+					       trans->msg_type);
 	}
 
 	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;
-- 
2.27.0

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Paul Moore]

On Fri, Mar 26, 2021 at 1:39 PM Richard Guy Briggs <rgb@redhat.com> wrote:
>
> 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 <rgb@redhat.com>
> ---
> Changelog:
> v5:
> (sorry for all the noise...)
> - fix kbuild missing prototype warning in nf_tables_commit_audit_{alloc,collect,log}() <lkp@intel.com>
>
> v4:
> - move nf_tables_commit_audit_log() before nf_tables_commit_release() [fw]
> - move nft2audit_op[] from audit.h to nf_tables_api.c
>
> v3:
> - fix function braces, reduce parameter scope [pna]
> - pre-allocate nft_audit_data per table in step 1, bail on ENOMEM [pna]
>
> v2:
> - convert NFT ops to array indicies in nft2audit_op[] [ps]
> - use linux lists [pna]
> - use functions for each of collection and logging of audit data [pna]
> ---
>  net/netfilter/nf_tables_api.c | 187 +++++++++++++++++++---------------
>  1 file changed, 104 insertions(+), 83 deletions(-)

Netfilter folks, were you planning to pull this via your tree/netdev
or would you like me to merge this via the audit tree?  If the latter,
I would appreciate it if I could get an ACK from one of you; if the
former, my ACK is below.

Acked-by: Paul Moore <paul@paul-moore.com>

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Pablo Neira Ayuso]

On Sun, Mar 28, 2021 at 08:50:45PM -0400, Paul Moore wrote:
[...]
> Netfilter folks, were you planning to pull this via your tree/netdev
> or would you like me to merge this via the audit tree?  If the latter,
> I would appreciate it if I could get an ACK from one of you; if the
> former, my ACK is below.
> 
> Acked-by: Paul Moore <paul@paul-moore.com>

I'll merge this one into nf-next, this might simplify possible
conflict resolution later on.

Thanks for acking.

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Paul Moore]

On Tue, Mar 30, 2021 at 6:53 PM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> On Sun, Mar 28, 2021 at 08:50:45PM -0400, Paul Moore wrote:
> [...]
> > Netfilter folks, were you planning to pull this via your tree/netdev
> > or would you like me to merge this via the audit tree?  If the latter,
> > I would appreciate it if I could get an ACK from one of you; if the
> > former, my ACK is below.
> >
> > Acked-by: Paul Moore <paul@paul-moore.com>
>
> I'll merge this one into nf-next, this might simplify possible
> conflict resolution later on.

Yep, I think that's the best choice.  Thanks.

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Pablo Neira Ayuso]

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On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> 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.

There's a UAF, Florian reported. I'm attaching an incremental fix.

nf_tables_commit_audit_collect() refers to the trans object which
might have been already released.

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commit e4d272948d25b66d86fc241cefd95281bfb1079e
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Wed Mar 31 22:19:51 2021 +0200

    netfilter: nf_tables: use-after-free
    
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 5dd4bb7cabf5..01674c0d9103 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8063,6 +8063,8 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 	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)) {
@@ -8211,8 +8213,6 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 			}
 			break;
 		}
-		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
-					       trans->msg_type);
 	}
 
 	nft_commit_notify(net, NETLINK_CB(skb).portid);

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Pablo Neira Ayuso]

On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> @@ -8006,12 +7966,65 @@ static void nft_commit_notify(struct net *net, u32 portid)
>  	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;
> +	INIT_LIST_HEAD(&adp->list);

This INIT_LIST_HEAD is not required for an object that is going to be
inserted into the 'adl' list.

> +	list_add(&adp->list, adl);

If no objections, I'll amend this patch. I'll include the UAF fix and
remove this unnecessary INIT_LIST_HEAD.

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Richard Guy Briggs]

On 2021-03-31 22:22, Pablo Neira Ayuso wrote:
> On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> > 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.
> 
> There's a UAF, Florian reported. I'm attaching an incremental fix.
> 
> nf_tables_commit_audit_collect() refers to the trans object which
> might have been already released.

Got it.  Thanks Pablo.  I didn't see it when running nft-test.py Where
was it reported?  Here I tried to stay out of the way by putting that
call at the end of the loop but that was obviously a mistake in
hindsight.  :-)

> commit e4d272948d25b66d86fc241cefd95281bfb1079e
> Author: Pablo Neira Ayuso <pablo@netfilter.org>
> Date:   Wed Mar 31 22:19:51 2021 +0200
> 
>     netfilter: nf_tables: use-after-free
>     
>     Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> 
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index 5dd4bb7cabf5..01674c0d9103 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -8063,6 +8063,8 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
>  	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)) {
> @@ -8211,8 +8213,6 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
>  			}
>  			break;
>  		}
> -		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
> -					       trans->msg_type);
>  	}
>  
>  	nft_commit_notify(net, NETLINK_CB(skb).portid);


- RGB

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Richard Guy Briggs]

On 2021-03-31 22:46, Pablo Neira Ayuso wrote:
> On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> > @@ -8006,12 +7966,65 @@ static void nft_commit_notify(struct net *net, u32 portid)
> >  	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;
> > +	INIT_LIST_HEAD(&adp->list);
> 
> This INIT_LIST_HEAD is not required for an object that is going to be
> inserted into the 'adl' list.
> 
> > +	list_add(&adp->list, adl);
> 
> If no objections, I'll amend this patch. I'll include the UAF fix and
> remove this unnecessary INIT_LIST_HEAD.

Ok, so it is harmless other than being code noise and overhead, thanks again.

- RGB

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Pablo Neira Ayuso]

On Wed, Mar 31, 2021 at 04:53:10PM -0400, Richard Guy Briggs wrote:
> On 2021-03-31 22:22, Pablo Neira Ayuso wrote:
> > On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> > > 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.
> > 
> > There's a UAF, Florian reported. I'm attaching an incremental fix.
> > 
> > nf_tables_commit_audit_collect() refers to the trans object which
> > might have been already released.
> 
> Got it.  Thanks Pablo.  I didn't see it when running nft-test.py Where
> was it reported?

CONFIG_KASAN.

> Here I tried to stay out of the way by putting that
> call at the end of the loop but that was obviously a mistake in
> hindsight.  :-)

No problem, I'll squash this incremental fix into your audit patch.

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Phil Sutter]

On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> 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 <rgb@redhat.com>

Tested this patch to make sure it eliminates the slowdown of
iptables-nft when auditd is running. With this applied, neither
iptables-nft-restore nor 'iptables-nft -F' show a significant
difference in run-time between running or stopped auditd, at least for
large rulesets. Individual calls suffer from added audit logging, but
that's expected of course.

Tested-by: Phil Sutter <phil@nwl.cc>

Thanks, Phil

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Re: [PATCH v5] audit: log nftables configuration change events once per table

[Richard Guy Briggs]

On 2021-04-01 15:24, Phil Sutter wrote:
> On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> > 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 <rgb@redhat.com>
> 
> Tested this patch to make sure it eliminates the slowdown of
> iptables-nft when auditd is running. With this applied, neither
> iptables-nft-restore nor 'iptables-nft -F' show a significant
> difference in run-time between running or stopped auditd, at least for
> large rulesets. Individual calls suffer from added audit logging, but
> that's expected of course.
> 
> Tested-by: Phil Sutter <phil@nwl.cc>

Excellent, thanks Phil for helping nail this one down and confirming the
fix.

> Thanks, Phil

- RGB

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