This is a note to let you know that I've just added the patch titled
debugfs: fix security_locked_down() call for SELinux
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 5881fa8dc2de9697a89451f6518e8b3a796c09c6 Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Date: Fri, 7 May 2021 14:53:04 +0200
Subject: debugfs: fix security_locked_down() call for SELinux
When (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) is zero, then
the SELinux implementation of the locked_down hook might report a denial
even though the operation would actually be allowed.
To fix this, make sure that security_locked_down() is called only when
the return value will be taken into account (i.e. when changing one of
the problematic attributes).
Note: this was introduced by commit 5496197f9b08 ("debugfs: Restrict
debugfs when the kernel is locked down"), but it didn't matter at that
time, as the SELinux support came in later.
Fixes: 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210507125304.144394-1-omosnace@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/debugfs/inode.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 1d252164d97b..8129a430d789 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -45,10 +45,13 @@ static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS;
static int debugfs_setattr(struct user_namespace *mnt_userns,
struct dentry *dentry, struct iattr *ia)
{
- int ret = security_locked_down(LOCKDOWN_DEBUGFS);
+ int ret;
- if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
- return ret;
+ if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) {
+ ret = security_locked_down(LOCKDOWN_DEBUGFS);
+ if (ret)
+ return ret;
+ }
return simple_setattr(&init_user_ns, dentry, ia);
}
--
2.31.1
