From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A07AC41621 for ; Mon, 8 Feb 2021 18:08:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2E2164E28 for ; Mon, 8 Feb 2021 18:08:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232317AbhBHSIa (ORCPT ); Mon, 8 Feb 2021 13:08:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:46602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235029AbhBHSDf (ORCPT ); Mon, 8 Feb 2021 13:03:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 950A264EF6; Mon, 8 Feb 2021 17:59:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612807173; bh=rVJgB9uoEMske98CMdEnJ6XPfiY1kyWyMRA678gkH4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Uwx5WuD06ppaAUZmlQdPgnbspP6E75C4fboJdMUxCQO3jsdXXE2NwyU6ZevRYxRaq d8ISXrtXq3sZIdBzwlrSnxoVCaaGea74/4SZGrkiAgLoxWU//hepvu8WVctpnwYdg/ mUuas1NZq0UVbURRN19kujqHWsmfpZy7Xh0IqflAmNFeg4b956hmk3hEpGvyA1+0b5 hTmdFFgt9sE4DUwg88vdOQmN0uVQ6GjoTKx1tqiOxIZh9jNYk9Ckg+K/7H+t0UOA8K 0RgUVaxiWn2YsjVRTGbfa0sZ3wZqg4zeRIaUmvMhZrE0WoY30T1d5tJ/vIKJdrMxUr NFAyLLg5wR6Rg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miklos Szeredi , "Eric W. Biederman" , Sasha Levin , linux-security-module@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 05/14] cap: fix conversions on getxattr Date: Mon, 8 Feb 2021 12:59:17 -0500 Message-Id: <20210208175926.2092211-5-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210208175926.2092211-1-sashal@kernel.org> References: <20210208175926.2092211-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: From: Miklos Szeredi [ Upstream commit f2b00be488730522d0fb7a8a5de663febdcefe0a ] If a capability is stored on disk in v2 format cap_inode_getsecurity() will currently return in v2 format unconditionally. This is wrong: v2 cap should be equivalent to a v3 cap with zero rootid, and so the same conversions performed on it. If the rootid cannot be mapped, v3 is returned unconverted. Fix this so that both v2 and v3 return -EOVERFLOW if the rootid (or the owner of the fs user namespace in case of v2) cannot be mapped into the current user namespace. Signed-off-by: Miklos Szeredi Acked-by: "Eric W. Biederman" Signed-off-by: Sasha Levin --- security/commoncap.c | 67 ++++++++++++++++++++++++++++---------------- 1 file changed, 43 insertions(+), 24 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index f86557a8e43f6..a1dee0ab345a2 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -377,10 +377,11 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, { int size, ret; kuid_t kroot; + u32 nsmagic, magic; uid_t root, mappedroot; char *tmpbuf = NULL; struct vfs_cap_data *cap; - struct vfs_ns_cap_data *nscap; + struct vfs_ns_cap_data *nscap = NULL; struct dentry *dentry; struct user_namespace *fs_ns; @@ -402,46 +403,61 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, fs_ns = inode->i_sb->s_user_ns; cap = (struct vfs_cap_data *) tmpbuf; if (is_v2header((size_t) ret, cap)) { - /* If this is sizeof(vfs_cap_data) then we're ok with the - * on-disk value, so return that. */ - if (alloc) - *buffer = tmpbuf; - else - kfree(tmpbuf); - return ret; - } else if (!is_v3header((size_t) ret, cap)) { - kfree(tmpbuf); - return -EINVAL; + root = 0; + } else if (is_v3header((size_t) ret, cap)) { + nscap = (struct vfs_ns_cap_data *) tmpbuf; + root = le32_to_cpu(nscap->rootid); + } else { + size = -EINVAL; + goto out_free; } - nscap = (struct vfs_ns_cap_data *) tmpbuf; - root = le32_to_cpu(nscap->rootid); kroot = make_kuid(fs_ns, root); /* If the root kuid maps to a valid uid in current ns, then return * this as a nscap. */ mappedroot = from_kuid(current_user_ns(), kroot); if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { + size = sizeof(struct vfs_ns_cap_data); if (alloc) { - *buffer = tmpbuf; + if (!nscap) { + /* v2 -> v3 conversion */ + nscap = kzalloc(size, GFP_ATOMIC); + if (!nscap) { + size = -ENOMEM; + goto out_free; + } + nsmagic = VFS_CAP_REVISION_3; + magic = le32_to_cpu(cap->magic_etc); + if (magic & VFS_CAP_FLAGS_EFFECTIVE) + nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; + memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); + nscap->magic_etc = cpu_to_le32(nsmagic); + } else { + /* use allocated v3 buffer */ + tmpbuf = NULL; + } nscap->rootid = cpu_to_le32(mappedroot); - } else - kfree(tmpbuf); - return size; + *buffer = nscap; + } + goto out_free; } if (!rootid_owns_currentns(kroot)) { - kfree(tmpbuf); - return -EOPNOTSUPP; + size = -EOVERFLOW; + goto out_free; } /* This comes from a parent namespace. Return as a v2 capability */ size = sizeof(struct vfs_cap_data); if (alloc) { - *buffer = kmalloc(size, GFP_ATOMIC); - if (*buffer) { - struct vfs_cap_data *cap = *buffer; - __le32 nsmagic, magic; + if (nscap) { + /* v3 -> v2 conversion */ + cap = kzalloc(size, GFP_ATOMIC); + if (!cap) { + size = -ENOMEM; + goto out_free; + } magic = VFS_CAP_REVISION_2; nsmagic = le32_to_cpu(nscap->magic_etc); if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) @@ -449,9 +465,12 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); cap->magic_etc = cpu_to_le32(magic); } else { - size = -ENOMEM; + /* use unconverted v2 */ + tmpbuf = NULL; } + *buffer = cap; } +out_free: kfree(tmpbuf); return size; } -- 2.27.0