[nf PATCH 1/2] netfilter: nf_tables: Audit log setelem reset

[Phil Sutter]

On Tue, Aug 29, 2023 at 08:02:30PM +0200, Pablo Neira Ayuso wrote:
> On Tue, Aug 29, 2023 at 07:51:57PM +0200, Phil Sutter wrote:
> > Since set element reset is not integrated into nf_tables' transaction
> > logic, an explicit log call is needed, similar to NFT_MSG_GETOBJ_RESET
> > handling.
> > 
> > For the sake of simplicity, catchall element reset will always generate
> > a dedicated log entry. This relieves nf_tables_dump_set() from having to
> > adjust the logged element count depending on whether a catchall element
> > was found or not.
> > 
> > Cc: Richard Guy Briggs <rgb at redhat.com>
> > Fixes: 079cd633219d7 ("netfilter: nf_tables: Introduce NFT_MSG_GETSETELEM_RESET")
> > Signed-off-by: Phil Sutter <phil at nwl.cc>
> > ---
> >  include/linux/audit.h         |  1 +
> >  kernel/auditsc.c              |  1 +
> >  net/netfilter/nf_tables_api.c | 31 ++++++++++++++++++++++++++++---
> >  3 files changed, 30 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 6a3a9e122bb5e..192bf03aacc52 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -117,6 +117,7 @@ enum audit_nfcfgop {
> >  	AUDIT_NFT_OP_OBJ_RESET,
> >  	AUDIT_NFT_OP_FLOWTABLE_REGISTER,
> >  	AUDIT_NFT_OP_FLOWTABLE_UNREGISTER,
> > +	AUDIT_NFT_OP_SETELEM_RESET,
> >  	AUDIT_NFT_OP_INVALID,
> >  };
> >  
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index addeed3df15d3..38481e3181975 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -143,6 +143,7 @@ static const struct audit_nfcfgop_tab audit_nfcfgs[] = {
> >  	{ 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_SETELEM_RESET,		"nft_reset_setelem"        },
> >  	{ AUDIT_NFT_OP_INVALID,			"nft_invalid"		   },
> >  };
> >  
> > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> > index 1ddbdca4e47d6..a1218ea4e0c3d 100644
> > --- a/net/netfilter/nf_tables_api.c
> > +++ b/net/netfilter/nf_tables_api.c
> > @@ -102,6 +102,7 @@ static const u8 nft2audit_op[NFT_MSG_MAX] = { // enum nf_tables_msg_types
> >  	[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_GETSETELEM_RESET] = AUDIT_NFT_OP_SETELEM_RESET,
> >  };
> >  
> >  static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
> > @@ -5661,13 +5662,25 @@ static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
> >  	return nf_tables_fill_setelem(args->skb, set, elem, args->reset);
> >  }
> >  
> > +static void audit_log_nft_set_reset(const struct nft_table *table,
> > +				    unsigned int base_seq,
> > +				    unsigned int nentries)
> > +{
> > +	char *buf = kasprintf(GFP_ATOMIC, "%s:%u", table->name, base_seq);
> 
> No check for NULL?
> 
> I can see we have more like this in the tree.

Well, I merely copy-pasted that bit. (No excuse, I know.) The pointer is
passed on to audit_log_format() as a string argument and will end at
vsnprintf(), which detects and sanitizes NULL string args.

Cheers, Phil