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audit: log nftables configuration change events once per table
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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>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Richard Guy Briggs authored and Pablo Neira Ayuso committed Mar 31, 2021
1 parent cefa31a commit c520292
Showing 1 changed file with 103 additions and 83 deletions.
186 changes: 103 additions & 83 deletions net/netfilter/nf_tables_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand Down Expand Up @@ -718,17 +753,6 @@ 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))
Expand Down Expand Up @@ -1502,18 +1526,6 @@ 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))
Expand Down Expand Up @@ -2866,18 +2878,6 @@ 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))
Expand Down Expand Up @@ -3912,18 +3912,6 @@ 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))
Expand Down Expand Up @@ -5108,18 +5096,6 @@ 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;
Expand Down Expand Up @@ -6321,12 +6297,11 @@ 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,
Expand Down Expand Up @@ -6447,8 +6422,8 @@ 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,
Expand Down Expand Up @@ -6536,15 +6511,15 @@ 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);

Expand Down Expand Up @@ -7362,18 +7337,6 @@ 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))
Expand Down Expand Up @@ -7494,9 +7457,6 @@ 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;
Expand Down Expand Up @@ -8035,12 +7995,64 @@ 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;
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)) {
Expand All @@ -8060,6 +8072,11 @@ 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;
Expand Down Expand Up @@ -8088,6 +8105,8 @@ 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)) {
Expand Down Expand Up @@ -8240,6 +8259,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)

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;
Expand Down

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