On Tue, Oct 16, 2018 at 02:04:20PM +0200, Jan Kara wrote:
> On Thu 11-10-18 21:43:09, Matthew Bobrowski wrote:
> > A new event type FAN_OPEN_EXEC_PERM has been defined. This allows users
> > to receive and grant access to files that are intending to be opened for
> > execution.
>
> The same note here as for FAN_OPEN_EXEC.
Updated.
I will include the updates to this within the updated patch series.
> > This acts in the same manor as previous permission event types, meaning
> > that a access response is required from the application to permit
> > further operations on the file. The event flag is set specifically when
> > the __FMODE_EXEC flag is set within file->f_flags in the fsnotify_perm()
> > hook.
> >
> > Signed-off-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
>
> And a general question: Do I understand right that your audit application
> needs this event type?
Yes, your understanding is correct. The application we're developing
requires this event type.
> I'm asking because so far what Steve wrote me was about pattern matching
> of fanotify events to detect when something happens. So it's not clear
> to me how permission event fits into that.
That detection for when "something happens", is precisely to do with
understanding when a file is opened for execution. We use permission
events within the application we're developing to either ALLOW or DENY a
particular action being performed against an object. At the moment, we
don't have any way to determine what actually caused a watched object to
be opened, so this is to aid with that, and also help us make a better
judgment how we're to respond to a particular action.
> > ---
> > fs/notify/fanotify/fanotify.c | 3 ++-
> > fs/notify/fsnotify.c | 2 +-
> > include/linux/fanotify.h | 3 ++-
> > include/linux/fsnotify.h | 10 ++++++----
> > include/linux/fsnotify_backend.h | 7 ++++---
> > include/uapi/linux/fanotify.h | 1 +
> > 6 files changed, 16 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> > index 9da334d343b8..bae9a312d772 100644
> > --- a/fs/notify/fanotify/fanotify.c
> > +++ b/fs/notify/fanotify/fanotify.c
> > @@ -212,8 +212,9 @@ static int fanotify_handle_event(struct fsnotify_group *group,
> > BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
> > BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
> > BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
> > + BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
> >
> > - BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 11);
> > + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 12);
> >
> > event_mask = fanotify_group_event_mask(iter_info, mask, data,
> > data_type);
> > diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> > index 051e5fc0dba1..40ed97aede29 100644
> > --- a/fs/notify/fsnotify.c
> > +++ b/fs/notify/fsnotify.c
> > @@ -402,7 +402,7 @@ static __init int fsnotify_init(void)
> > {
> > int ret;
> >
> > - BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 24);
> > + BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25);
> >
> > ret = init_srcu_struct(&fsnotify_mark_srcu);
> > if (ret)
> > diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
> > index 0e07d23b6c17..614943153596 100644
> > --- a/include/linux/fanotify.h
> > +++ b/include/linux/fanotify.h
> > @@ -42,7 +42,8 @@
> > FAN_CLOSE | FAN_OPEN | FAN_OPEN_EXEC)
> >
> > /* Events that require a permission response from user */
> > -#define FANOTIFY_PERM_EVENTS (FAN_OPEN_PERM | FAN_ACCESS_PERM)
> > +#define FANOTIFY_PERM_EVENTS (FAN_OPEN_PERM | FAN_ACCESS_PERM | \
> > + FAN_OPEN_EXEC_PERM)
> >
> > /* Extra flags that may be reported with event or control handling of events */
> > #define FANOTIFY_EVENT_FLAGS (FAN_EVENT_ON_CHILD | FAN_ONDIR)
> > diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
> > index 1fe5ac93b252..6fb8d1fcfeaf 100644
> > --- a/include/linux/fsnotify.h
> > +++ b/include/linux/fsnotify.h
> > @@ -38,12 +38,14 @@ static inline int fsnotify_perm(struct file *file, int mask)
> > return 0;
> > if (!(mask & (MAY_READ | MAY_OPEN)))
> > return 0;
> > - if (mask & MAY_OPEN)
> > + if (mask & MAY_OPEN) {
> > fsnotify_mask = FS_OPEN_PERM;
> > - else if (mask & MAY_READ)
> > +
> > + if (file->f_flags & __FMODE_EXEC)
> > + fsnotify_mask |= FS_OPEN_EXEC_PERM;
> > + } else if (mask & MAY_READ) {
> > fsnotify_mask = FS_ACCESS_PERM;
> > - else
> > - BUG();
> > + }
> >
> > ret = fsnotify_parent(path, NULL, fsnotify_mask);
> > if (ret)
> > diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> > index 329ac6684326..96616651220c 100644
> > --- a/include/linux/fsnotify_backend.h
> > +++ b/include/linux/fsnotify_backend.h
> > @@ -44,8 +44,9 @@
> > #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
> > #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
> >
> > -#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
> > +#define FS_OPEN_PERM 0x00010000 /* open event in a permission hook */
> > #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
> > +#define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec in a permission hook */
> >
> > #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
> > #define FS_ISDIR 0x40000000 /* event occurred against dir */
> > @@ -64,7 +65,7 @@
> > FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
> > FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
> > FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM |\
> > - FS_OPEN_EXEC)
> > + FS_OPEN_EXEC | FS_OPEN_EXEC_PERM)
> >
> > #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
> >
> > @@ -77,7 +78,7 @@
> > FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
> > FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
> > FS_OPEN_PERM | FS_ACCESS_PERM | FS_DN_RENAME |\
> > - FS_OPEN_EXEC)
> > + FS_OPEN_EXEC | FS_OPEN_EXEC_PERM)
> >
> > /* Extra flags that may be reported with event or control handling of events */
> > #define ALL_FSNOTIFY_FLAGS (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
> > diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
> > index da278f11ab29..e2df10c61cb1 100644
> > --- a/include/uapi/linux/fanotify.h
> > +++ b/include/uapi/linux/fanotify.h
> > @@ -16,6 +16,7 @@
> >
> > #define FAN_OPEN_PERM 0x00010000 /* File open in perm check */
> > #define FAN_ACCESS_PERM 0x00020000 /* File accessed in perm check */
> > +#define FAN_OPEN_EXEC_PERM 0x00040000 /* File open/exec in perm check */
> >
> > #define FAN_ONDIR 0x40000000 /* event occurred against dir */
> >
> > --
> > 2.17.2
> >
> --
> Jan Kara <jack@xxxxxxxx>
> SUSE Labs, CR
