Re: [PATCH v4 3/3] audit: add OPENAT2 record to list how

[Paul Moore]

On Thu, May 20, 2021 at 4:03 AM Christian Brauner
<christian.brauner@xxxxxxxxxx> wrote:
> On Wed, May 19, 2021 at 04:00:22PM -0400, Richard Guy Briggs wrote:
> > Since the openat2(2) syscall uses a struct open_how pointer to communicate
> > its parameters they are not usefully recorded by the audit SYSCALL record's
> > four existing arguments.
> >
> > Add a new audit record type OPENAT2 that reports the parameters in its
> > third argument, struct open_how with fields oflag, mode and resolve.
> >
> > The new record in the context of an event would look like:
> > time->Wed Mar 17 16:28:53 2021
> > type=PROCTITLE msg=audit(1616012933.531:184): proctitle=73797363616C6C735F66696C652F6F70656E617432002F746D702F61756469742D7465737473756974652D737641440066696C652D6F70656E617432
> > type=PATH msg=audit(1616012933.531:184): item=1 name="file-openat2" inode=29 dev=00:1f mode=0100600 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=CREATE cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
> > type=PATH msg=audit(1616012933.531:184): item=0 name="/root/rgb/git/audit-testsuite/tests" inode=25 dev=00:1f mode=040700 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:user_tmp_t:s0 nametype=PARENT cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
> > type=CWD msg=audit(1616012933.531:184): cwd="/root/rgb/git/audit-testsuite/tests"
> > type=OPENAT2 msg=audit(1616012933.531:184): oflag=0100302 mode=0600 resolve=0xa
> > type=SYSCALL msg=audit(1616012933.531:184): arch=c000003e syscall=437 success=yes exit=4 a0=3 a1=7ffe315f1c53 a2=7ffe315f1550 a3=18 items=2 ppid=528 pid=540 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=1 comm="openat2" exe="/root/rgb/git/audit-testsuite/tests/syscalls_file/openat2" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key="testsuite-1616012933-bjAUcEPO"
> >
> > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > Link: https://lore.kernel.org/r/d23fbb89186754487850367224b060e26f9b7181.1621363275.git.rgb@xxxxxxxxxx
> > ---
> >  fs/open.c                  |  2 ++
> >  include/linux/audit.h      | 10 ++++++++++
> >  include/uapi/linux/audit.h |  1 +
> >  kernel/audit.h             |  2 ++
> >  kernel/auditsc.c           | 18 +++++++++++++++++-
> >  5 files changed, 32 insertions(+), 1 deletion(-)

...

> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index 3f59ab209dfd..faf2485323a9 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -76,7 +76,7 @@
> >  #include <linux/fsnotify_backend.h>
> >  #include <uapi/linux/limits.h>
> >  #include <uapi/linux/netfilter/nf_tables.h>
> > -#include <uapi/linux/openat2.h>
> > +#include <uapi/linux/openat2.h> // struct open_how
> >
> >  #include "audit.h"
> >
> > @@ -1319,6 +1319,12 @@ static void show_special(struct audit_context *context, int *call_panic)
> >               audit_log_format(ab, "fd=%d flags=0x%x", context->mmap.fd,
> >                                context->mmap.flags);
> >               break;
> > +     case AUDIT_OPENAT2:
> > +             audit_log_format(ab, "oflag=0%llo mode=0%llo resolve=0x%llx",
>
> Hm, should we maybe follow the struct member names for all entries, i.e.
> replace s/oflag/flags?

There is some precedence for using "oflags" to refer to "open" flags,
my guess is Richard is trying to be consistent here.  I agree it's a
little odd, but it looks like the right thing to me from an audit
perspective; the audit perspective is a little odd after all :)

-- 
paul moore
www.paul-moore.com