@@ -45,10 +45,13 @@ static unsigned int debugfs_allow = 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);
}
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") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> --- v2: try to explain the problem better in the description fs/debugfs/inode.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)