From: Ondrej Mosnacek <omosnace@redhat.com> mainline inclusion from mainline-5.13-rc4 commit 5881fa8dc2de9697a89451f6518e8b3a796c09c6 category: bugfix issue: #I3ZXZF CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------------- 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@vger.kernel.org> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Link: https://lore.kernel.org/r/20210507125304.144394-1-omosnace@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: fs/debugfs/inode.c Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> Signed-off-by: Yu Changchun <yuchangchun1@huawei.com> --- 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 720d65f224f0..dc3ea2833a9e 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -44,10 +44,13 @@ static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS; */ static int debugfs_setattr(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(dentry, ia); } -- 2.22.0