From 5881fa8dc2de9697a89451f6518e8b3a796c09c6 Mon Sep 17 00:00:00 2001 From: Ondrej Mosnacek 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 Signed-off-by: Ondrej Mosnacek Link: https://lore.kernel.org/r/20210507125304.144394-1-omosnace@redhat.com Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'fs') 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); } -- cgit v1.2.3