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    SubjectRe: [PATCH ghak124 v3] audit: log nftables configuration change events
    Date
    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.

    -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;




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