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Date:   Mon, 18 Mar 2019 19:47:16 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Ondrej Mosnacek <omosnace@...hat.com>
Cc:     containers@...ts.linux-foundation.org, linux-api@...r.kernel.org,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
        Paul Moore <paul@...l-moore.com>,
        Steve Grubb <sgrubb@...hat.com>,
        David Howells <dhowells@...hat.com>, simo@...hat.com,
        Eric Paris <eparis@...isplace.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>, nhorman@...driver.com
Subject: Re: [PATCH ghak90 V5 08/10] audit: add containerid filtering

On 2019-03-18 21:02, Ondrej Mosnacek wrote:
> On Fri, Mar 15, 2019 at 7:35 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> >
> > Implement audit container identifier filtering using the AUDIT_CONTID
> > field name to send an 8-character string representing a u64 since the
> > value field is only u32.
> >
> > Sending it as two u32 was considered, but gathering and comparing two
> > fields was more complex.
> >
> > The feature indicator is AUDIT_FEATURE_BITMAP_CONTAINERID.
> >
> > See: https://github.com/linux-audit/audit-kernel/issues/91
> > See: https://github.com/linux-audit/audit-userspace/issues/40
> > See: https://github.com/linux-audit/audit-testsuite/issues/64
> > See: https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID
> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > Acked-by: Serge Hallyn <serge@...lyn.com>
> > ---
> >  include/linux/audit.h      |  1 +
> >  include/uapi/linux/audit.h |  5 ++++-
> >  kernel/audit.h             |  1 +
> >  kernel/auditfilter.c       | 47 ++++++++++++++++++++++++++++++++++++++++++++++
> >  kernel/auditsc.c           |  3 +++
> >  5 files changed, 56 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 6db5aba7cc01..fa19fa408931 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -77,6 +77,7 @@ struct audit_field {
> >         u32                             type;
> >         union {
> >                 u32                     val;
> > +               u64                     val64;
> >                 kuid_t                  uid;
> >                 kgid_t                  gid;
> >                 struct {
> > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > index a6383e28b2c8..741ab6f38294 100644
> > --- a/include/uapi/linux/audit.h
> > +++ b/include/uapi/linux/audit.h
> > @@ -265,6 +265,7 @@
> >  #define AUDIT_LOGINUID_SET     24
> >  #define AUDIT_SESSIONID        25      /* Session ID */
> >  #define AUDIT_FSTYPE   26      /* FileSystem Type */
> > +#define AUDIT_CONTID   27      /* Container ID */
> >
> >                                 /* These are ONLY useful when checking
> >                                  * at syscall exit time (AUDIT_AT_EXIT). */
> > @@ -345,6 +346,7 @@ enum {
> >  #define AUDIT_FEATURE_BITMAP_SESSIONID_FILTER  0x00000010
> >  #define AUDIT_FEATURE_BITMAP_LOST_RESET                0x00000020
> >  #define AUDIT_FEATURE_BITMAP_FILTER_FS         0x00000040
> > +#define AUDIT_FEATURE_BITMAP_CONTAINERID       0x00000080
> >
> >  #define AUDIT_FEATURE_BITMAP_ALL (AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT | \
> >                                   AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME | \
> > @@ -352,7 +354,8 @@ enum {
> >                                   AUDIT_FEATURE_BITMAP_EXCLUDE_EXTEND | \
> >                                   AUDIT_FEATURE_BITMAP_SESSIONID_FILTER | \
> >                                   AUDIT_FEATURE_BITMAP_LOST_RESET | \
> > -                                 AUDIT_FEATURE_BITMAP_FILTER_FS)
> > +                                 AUDIT_FEATURE_BITMAP_FILTER_FS | \
> > +                                 AUDIT_FEATURE_BITMAP_CONTAINERID)
> >
> >  /* deprecated: AUDIT_VERSION_* */
> >  #define AUDIT_VERSION_LATEST           AUDIT_FEATURE_BITMAP_ALL
> > diff --git a/kernel/audit.h b/kernel/audit.h
> > index 2a1a8b8a8019..3a40b608bf8d 100644
> > --- a/kernel/audit.h
> > +++ b/kernel/audit.h
> > @@ -230,6 +230,7 @@ static inline int audit_hash_ino(u32 ino)
> >
> >  extern int audit_match_class(int class, unsigned syscall);
> >  extern int audit_comparator(const u32 left, const u32 op, const u32 right);
> > +extern int audit_comparator64(const u64 left, const u32 op, const u64 right);
> >  extern int audit_uid_comparator(kuid_t left, u32 op, kuid_t right);
> >  extern int audit_gid_comparator(kgid_t left, u32 op, kgid_t right);
> >  extern int parent_len(const char *path);
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index add360b46b38..516b8e58959e 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -410,6 +410,7 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
> >         /* FALL THROUGH */
> >         case AUDIT_ARCH:
> >         case AUDIT_FSTYPE:
> > +       case AUDIT_CONTID:
> >                 if (f->op != Audit_not_equal && f->op != Audit_equal)
> >                         return -EINVAL;
> >                 break;
> > @@ -582,6 +583,14 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
> >                         }
> >                         entry->rule.exe = audit_mark;
> >                         break;
> > +               case AUDIT_CONTID:
> > +                       if (f->val != sizeof(u64))
> > +                               goto exit_free;
> > +                       str = audit_unpack_string(&bufp, &remain, f->val);
> > +                       if (IS_ERR(str))
> > +                               goto exit_free;
> > +                       f->val64 = ((u64 *)str)[0];
> > +                       break;
> >                 }
> >         }
> >
> > @@ -664,6 +673,11 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
> >                         data->buflen += data->values[i] =
> >                                 audit_pack_string(&bufp, audit_mark_path(krule->exe));
> >                         break;
> > +               case AUDIT_CONTID:
> > +                       data->buflen += data->values[i] = sizeof(u64);
> > +                       for (i = 0; i < sizeof(u64); i++)
> > +                               ((char *)bufp)[i] = ((char *)&f->val64)[i];
> 
> How about just:
> 
> memcpy(bufp, &f->val64, sizeof(u64));
> 
> instead of the awkward for loop? It is simpler and also more in line
> with the code in audit_pack_string().

I'll grant you that.  I'll use that instead.

> Also, doesn't this loop interfere with the outer loop that also uses
> 'i' as the control variable?

Yes, it does.  Thank you for catching that.  Doing a auditctl -l reveals
this.

> > +                       break;
> >                 case AUDIT_LOGINUID_SET:
> >                         if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) {
> >                                 data->fields[i] = AUDIT_LOGINUID;
> > @@ -750,6 +764,10 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
> >                         if (!gid_eq(a->fields[i].gid, b->fields[i].gid))
> >                                 return 1;
> >                         break;
> > +               case AUDIT_CONTID:
> > +                       if (a->fields[i].val64 != b->fields[i].val64)
> > +                               return 1;
> > +                       break;
> >                 default:
> >                         if (a->fields[i].val != b->fields[i].val)
> >                                 return 1;
> > @@ -1206,6 +1224,31 @@ int audit_comparator(u32 left, u32 op, u32 right)
> >         }
> >  }
> >
> > +int audit_comparator64(u64 left, u32 op, u64 right)
> > +{
> > +       switch (op) {
> > +       case Audit_equal:
> > +               return (left == right);
> > +       case Audit_not_equal:
> > +               return (left != right);
> > +       case Audit_lt:
> > +               return (left < right);
> > +       case Audit_le:
> > +               return (left <= right);
> > +       case Audit_gt:
> > +               return (left > right);
> > +       case Audit_ge:
> > +               return (left >= right);
> > +       case Audit_bitmask:
> > +               return (left & right);
> > +       case Audit_bittest:
> > +               return ((left & right) == right);
> > +       default:
> > +               BUG();
> > +               return 0;
> > +       }
> > +}
> > +
> >  int audit_uid_comparator(kuid_t left, u32 op, kuid_t right)
> >  {
> >         switch (op) {
> > @@ -1344,6 +1387,10 @@ int audit_filter(int msgtype, unsigned int listtype)
> >                                 result = audit_comparator(audit_loginuid_set(current),
> >                                                           f->op, f->val);
> >                                 break;
> > +                       case AUDIT_CONTID:
> > +                               result = audit_comparator64(audit_get_contid(current),
> > +                                                             f->op, f->val64);
> > +                               break;
> >                         case AUDIT_MSGTYPE:
> >                                 result = audit_comparator(msgtype, f->op, f->val);
> >                                 break;
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index aa5d13b4fbbb..2d74238e9638 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -616,6 +616,9 @@ static int audit_filter_rules(struct task_struct *tsk,
> >                 case AUDIT_LOGINUID_SET:
> >                         result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val);
> >                         break;
> > +               case AUDIT_CONTID:
> > +                       result = audit_comparator64(audit_get_contid(tsk), f->op, f->val64);
> > +                       break;
> >                 case AUDIT_SUBJ_USER:
> >                 case AUDIT_SUBJ_ROLE:
> >                 case AUDIT_SUBJ_TYPE:
> > --
> > 1.8.3.1
> >
> 
> 
> -- 
> Ondrej Mosnacek <omosnace at redhat dot com>
> Associate Software Engineer, Security Technologies
> Red Hat, Inc.

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635

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