Re: [PATCH ghak124 v2] audit: log nftables configuration change events

On Thu, May 28, 2020 at 9:44 PM Richard Guy Briggs <rgb(a)redhat.com&gt; 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(a)redhat.com&gt; > --- > Changelog: > 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 | 52 +++++++++++++++++++++++++ > kernel/auditsc.c | 24 ++++++++++-- > net/netfilter/nf_tables_api.c | 89 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 162 insertions(+), 3 deletions(-) > > diff --git a/include/linux/audit.h b/include/linux/audit.h > index 3fcd9ee49734..d79866a38505 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 +99,57 @@ 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, > +}; > + > +struct audit_nftcfgop_tab { > + enum nf_tables_msg_types nftop; > + enum audit_nfcfgop op; > +}; > + > +static const struct audit_nftcfgop_tab audit_nftcfgs[] = { > + { 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 }, > + { NFT_MSG_MAX, AUDIT_NFT_OP_INVALID }, > }; I didn't check every "op" defined above to match with the changes in nf_tables_api.c, but is there a reason why we can't simply hardcode the AUDIT_NFT_OP_* values in the audit_log_nfcfg() calls in nf_tables_api.c? If we can, let's do that.

If we can't do that, we need to add some build-time protection to catch if NFT_MSG_MAX increases without this table being updated.

> 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 4471393da6d8..7a386eca6e04 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 +694,14 @@ 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, > + audit_nftcfgs[event].op); As an example, the below would work, yes? audit_log_nfcfg(..., (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)) paul moore