Re: [userspace PATCH v2 2/2] Check exclude filter cred extension fields available in kernel

[Richard Guy Briggs <rgb@redhat.com>]

On 2016-10-10 13:47, Steve Grubb wrote:
> On Thursday, August 18, 2016 2:33:20 PM EDT Richard Guy Briggs wrote:
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > ---
> >  trunk/lib/errormsg.h |    2 +-
> >  trunk/lib/libaudit.c |   39 ++++++++++++++++++++++-----------------
> >  trunk/lib/libaudit.h |    3 +++
> >  3 files changed, 26 insertions(+), 18 deletions(-)
> > 
> > diff --git a/trunk/lib/errormsg.h b/trunk/lib/errormsg.h
> > index 84bfdb3..4a897be 100644
> > --- a/trunk/lib/errormsg.h
> > +++ b/trunk/lib/errormsg.h
> > @@ -47,7 +47,7 @@ static const struct msg_tab err_msgtab[] = {
> >      { -9,    0,    "msgtype field can only be used with exclude filter
> > list" }, { -10,    0,    "Failed upgrading rule" },
> >      { -11,    0,    "String value too long" },
> > -    { -12,    0,    "Only msgtype field can be used with exclude filter" },
> > +    { -12,    0,    "Only msgtype, uid, gid, auid*, subj* fields can be
> > used with exclude filter" }, { -13,    1,    "only takes = or != operators"
> > },
> >      { -14,    0,    "Permission can only contain  \'rwxa\'" },
> >      { -15,    2,    "-F unknown errno -"},
> > diff --git a/trunk/lib/libaudit.c b/trunk/lib/libaudit.c
> > index 798b3c8..5ffc38c 100644
> > --- a/trunk/lib/libaudit.c
> > +++ b/trunk/lib/libaudit.c
> > @@ -1401,23 +1401,28 @@ int audit_rule_fieldpair_data(struct audit_rule_data
> > **rulep, const char *pair, return -2;
> > 
> >  	/* Exclude filter can be used only with MSGTYPE and cred fields */
> > -	if (flags == AUDIT_FILTER_EXCLUDE)
> > -		switch(field) {
> > -			case AUDIT_PID:
> > -			case AUDIT_UID:
> > -			case AUDIT_GID:
> > -			case AUDIT_LOGINUID:
> > -			case AUDIT_LOGINUID_SET:
> > -			case AUDIT_MSGTYPE:
> > -			case AUDIT_SUBJ_USER:
> > -			case AUDIT_SUBJ_ROLE:
> > -			case AUDIT_SUBJ_TYPE:
> > -			case AUDIT_SUBJ_SEN:
> > -			case AUDIT_SUBJ_CLR:
> > -				break;
> > -			default:
> > -				return -12;
> > -		}
> > +	if (flags == AUDIT_FILTER_EXCLUDE) {
> > +		if ((features & AUDIT_FEATURE_BITMAP_EXCLUDE_EXTEND) == 0) {
> 
> One question, why is this being and'ed directly? I was told that we have to go 
> through AUDIT_FEATURE_TO_MASK() to convert the value to a mask which can then 
> be and'ed. Is this macro now deprecated?

I was going to congratulate you on a nice catch, but
AUDIT_GET/SET_FEATURE and AUDIT_FEATURE_BITMAP are two different things.

The former gets and sets the state of features while the latter replaced
AUDIT_VERSION and simply checks for the presence of a backported
feature.

> -Steve
> 
> > +			if (field != AUDIT_MSGTYPE)
> > +				return -30;
> > +		} else
> > +			switch(field) {
> > +				case AUDIT_PID:
> > +				case AUDIT_UID:
> > +				case AUDIT_GID:
> > +				case AUDIT_LOGINUID:
> > +				case AUDIT_LOGINUID_SET:
> > +				case AUDIT_MSGTYPE:
> > +				case AUDIT_SUBJ_USER:
> > +				case AUDIT_SUBJ_ROLE:
> > +				case AUDIT_SUBJ_TYPE:
> > +				case AUDIT_SUBJ_SEN:
> > +				case AUDIT_SUBJ_CLR:
> > +					break;
> > +				default:
> > +					return -12;
> > +			}
> > +	}
> > 
> >  	rule->fields[rule->field_count] = field;
> >  	rule->fieldflags[rule->field_count] = op;
> > diff --git a/trunk/lib/libaudit.h b/trunk/lib/libaudit.h
> > index 0852bcc..f77691f 100644
> > --- a/trunk/lib/libaudit.h
> > +++ b/trunk/lib/libaudit.h
> > @@ -278,6 +278,9 @@ extern "C" {
> >  #ifndef AUDIT_FEATURE_BITMAP_EXECUTABLE_PATH
> >  #define AUDIT_FEATURE_BITMAP_EXECUTABLE_PATH    0x00000004
> >  #endif
> > +#ifndef AUDIT_FEATURE_BITMAP_EXCLUDE_EXTEND
> > +#define AUDIT_FEATURE_BITMAP_EXCLUDE_EXTEND	0x00000008
> > +#endif
> > 
> >  /* Defines for interfield comparison update */
> >  #ifndef AUDIT_OBJ_UID
> 
> 

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Kernel Security Engineering, Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635