git: b34127064fde - stable/12 - pf: Set the pfik_group for userspace

[Kristof Provost]

The branch stable/12 has been updated by kp:

URL: https://cgit.FreeBSD.org/src/commit/?id=b34127064fde4d144b6d63dce0eada01563bc562

commit b34127064fde4d144b6d63dce0eada01563bc562
Author:     Kristof Provost <kp at FreeBSD.org>
AuthorDate: 2021-05-16 06:50:17 +0000
Commit:     Kristof Provost <kp at FreeBSD.org>
CommitDate: 2021-05-24 15:40:28 +0000

    pf: Set the pfik_group for userspace
    
    Userspace relies on this pointer to work out if the kif is a group or
    not. It can't use it for anything else, because it's a pointer to a
    kernel address. Substitute 0xfeedc0de for 'true', so that we don't leak
    kernel memory addresses to userspace.
    
    PR:             255852
    Reviewed by:    donner
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D30284
    
    (cherry picked from commit d69cc040147284c414dfd1c9f498dcc7c8291a8b)
---
 sys/netpfil/pf/pf_if.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sys/netpfil/pf/pf_if.c b/sys/netpfil/pf/pf_if.c
index 656cdfab6018..9c10be3b3b77 100644
--- a/sys/netpfil/pf/pf_if.c
+++ b/sys/netpfil/pf/pf_if.c
@@ -817,6 +817,14 @@ pf_kkif_to_kif(const struct pfi_kkif *kkif, struct pfi_kif *kif)
 	kif->pfik_flags = kkif->pfik_flags;
 	kif->pfik_tzero = kkif->pfik_tzero;
 	kif->pfik_rulerefs = kkif->pfik_rulerefs;
+	/*
+	 * Userspace relies on this pointer to decide if this is a group or
+	 * not. We don't want to share the actual pointer, because it's
+	 * useless to userspace and leaks kernel memory layout information.
+	 * So instead we provide 0xfeedcode as 'true' and NULL as 'false'.
+	 */
+	kif->pfik_group =
+	    kkif->pfik_group ? (struct ifg_group *)0xfeedc0de : NULL;
 }
 
 void