[PATCH ghak124 v2] audit: log nftables configuration change events
Paul Moore
paul at paul-moore.com
Mon Jun 1 16:10:44 UTC 2020
On Thu, May 28, 2020 at 9:44 PM Richard Guy Briggs <rgb at redhat.com> 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 at redhat.com>
> ---
> 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
www.paul-moore.com
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