linux-kernel - Re: [PATCH ghak124 v3] audit: log nftables configuration change events

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Message-ID: <2190308.cDvYnDs5iT@x2>
Date:   Thu, 04 Jun 2020 14:51:54 -0400
From:   Steve Grubb <sgrubb@...hat.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        netfilter-devel@...r.kernel.org, Paul Moore <paul@...l-moore.com>,
        omosnace@...hat.com, fw@...len.de, twoerner@...hat.com,
        eparis@...isplace.org, tgraf@...radead.org
Subject: Re: [PATCH ghak124 v3] audit: log nftables configuration change events

On Thursday, June 4, 2020 1:57:56 PM EDT Richard Guy Briggs wrote:
> > > 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.
> 
> That is a good idea that would help reduce kernel cycles and netlink
> bandwidth, but the format was set in 2011 so it is a bit late to change
> that now:
>         fbabf31e4d48 ("netfilter: create audit records for x_tables
> replaces")

Nothing searches/interprets that field name. So, you can redefine it by 
renaming it. Or just go with what you have. My preference is push that to 
user space. But not a showstopper "as is".

-Steve