From patchwork Thu Aug 29 18:30:14 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Salyzyn X-Patchwork-Id: 11122251 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8518F1395 for ; Thu, 29 Aug 2019 18:30:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60AD7233FF for ; Thu, 29 Aug 2019 18:30:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="isJCPHV3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729137AbfH2Sab (ORCPT ); Thu, 29 Aug 2019 14:30:31 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:33493 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729197AbfH2Saa (ORCPT ); Thu, 29 Aug 2019 14:30:30 -0400 Received: by mail-pf1-f194.google.com with SMTP id g2so2654535pfq.0 for ; Thu, 29 Aug 2019 11:30:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=t7rGaqUzAk36ILWcKr/jrH6Y9v6WlXTDUlDGIYS/FWg=; b=isJCPHV3UCx5mYklMoclrNYYLuiDQl8rOsozhV+AOuvC+A2RL6Of1dXi59VVYyJ8Yh nbEhIdofSeqRVf4HCfoE6ntd1M93ZOHul+nGhedXl4X/3a2yARQ0GOzfEQ15nzNgQYPB 1qKP8GgA9JnCgMRJQUtSXxcy4vfrkx21r3RNVe3qyvObBnL8kD7niQLjxUF4okFXNipE xH4SbLpar4QTNbuR639sRK9Rl7AjtvDaXh7RxA2QQ5TQMMwH7Jvn/lt+jb0pKjCbx2kA nIW6xVEvasZpHC5rUvv6GxUt4FvYgKMyRkjbLb/Yai1SwPEGGgtc9v1G/s23AMVOJplX pIfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=t7rGaqUzAk36ILWcKr/jrH6Y9v6WlXTDUlDGIYS/FWg=; b=IBgBbqcRlz1JXvK+F8MasSnZH9VoUrzlSXWb74idfSysyq/KRArG9vv8q2vfhz+z6X vap/aebyrD/h1gnGmMyn4jVacF6arFyIYDahBTE3FMG+5xej1a5l+Rqr/EDPdfEjDYRj tjPO7rlrrSr4Du7I/zgLMtgXV4xh6oZSTU9/71trSo33Zp2aUOjrdZ8efnqi0jc9ZuQA 32/Y2for1XFq1qqTZBj+9Ajba/u1Z6QguZYskW4B+ikpZqOUHeb6lg5Wx8WwH7fZL1Uv rQqfYNN2PQ3pN0SgqN9vFlW+BxUDbVBwHc4em8pzi6nnelmEMoAIpC7MpPihcxk8a3h5 DapQ== X-Gm-Message-State: APjAAAUJkosABRqSxHgskR2pb75XWazWX/WgWH3pmO7+MVX2OWl+i752 nYVZuJehFpEBCf3BtOh8R820gw== X-Google-Smtp-Source: APXvYqw/vXkr0PEX/jzpgnhtbh7cvLECq0WihqgmP+dtE4STT7/cXn7PqLsTujfn/flbDd+wdX6iYg== X-Received: by 2002:a63:c84d:: with SMTP id l13mr9620053pgi.154.1567103429436; Thu, 29 Aug 2019 11:30:29 -0700 (PDT) Received: from nebulus.mtv.corp.google.com ([2620:15c:211:200:5404:91ba:59dc:9400]) by smtp.gmail.com with ESMTPSA id y16sm4090168pfc.36.2019.08.29.11.30.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Aug 2019 11:30:28 -0700 (PDT) From: Mark Salyzyn To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Mark Salyzyn , linux-kernel@vger.kernel.orga, linux-security-module@vger.kernel.org, stable@vger.kernel.org, Miklos Szeredi , linux-unionfs@vger.kernel.org Subject: [PATCH] overlayfs: filter of trusted xattr results in audit. Date: Thu, 29 Aug 2019 11:30:14 -0700 Message-Id: <20190829183021.87586-1-salyzyn@android.com> X-Mailer: git-send-email 2.23.0.187.g17f5b7556c-goog MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present. Switch to ns_capable_noaudit to reflect a more appropriate check. Signed-off-by: Mark Salyzyn Cc: linux-kernel@vger.kernel.orga Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: stable@vger.kernel.org # 4.4, 4.9, 4.14 & 4.19 --- fs/overlayfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 7663aeb85fa3..bc14781886bf 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -383,7 +383,8 @@ static bool ovl_can_list(const char *s) return true; /* Never list trusted.overlay, list other trusted for superuser only */ - return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); + return !ovl_is_private_xattr(s) && + ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN); } ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)