From: Paul Moore <paul@paul-moore.com>
To: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, Seth Forshee <sforshee@kernel.org>,
Christoph Hellwig <hch@lst.de>, Al Viro <viro@zeniv.linux.org.uk>,
Mimi Zohar <zohar@linux.ibm.com>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH v5 12/30] integrity: implement get and set acl hook
Date: Tue, 18 Oct 2022 15:17:55 -0400 [thread overview]
Message-ID: <CAHC9VhSWymFrrV2Zu3isAivuZMvgBxagkoDg3vLGDOww=Y8t_Q@mail.gmail.com> (raw)
In-Reply-To: <20221018115700.166010-13-brauner@kernel.org>
On Tue, Oct 18, 2022 at 7:59 AM Christian Brauner <brauner@kernel.org> wrote:
>
> The current way of setting and getting posix acls through the generic
> xattr interface is error prone and type unsafe. The vfs needs to
> interpret and fixup posix acls before storing or reporting it to
> userspace. Various hacks exist to make this work. The code is hard to
> understand and difficult to maintain in it's current form. Instead of
> making this work by hacking posix acls through xattr handlers we are
> building a dedicated posix acl api around the get and set inode
> operations. This removes a lot of hackiness and makes the codepaths
> easier to maintain. A lot of background can be found in [1].
>
> So far posix acls were passed as a void blob to the security and
> integrity modules. Some of them like evm then proceed to interpret the
> void pointer and convert it into the kernel internal struct posix acl
> representation to perform their integrity checking magic. This is
> obviously pretty problematic as that requires knowledge that only the
> vfs is guaranteed to have and has lead to various bugs. Add a proper
> security hook for setting posix acls and pass down the posix acls in
> their appropriate vfs format instead of hacking it through a void
> pointer stored in the uapi format.
>
> I spent considerate time in the security module and integrity
> infrastructure and audited all codepaths. EVM is the only part that
> really has restrictions based on the actual posix acl values passed
> through it (e.g., i_mode). Before this dedicated hook EVM used to translate
> from the uapi posix acl format sent to it in the form of a void pointer
> into the vfs format. This is not a good thing. Instead of hacking around in
> the uapi struct give EVM the posix acls in the appropriate vfs format and
> perform sane permissions checks that mirror what it used to to in the
> generic xattr hook.
>
> IMA doesn't have any restrictions on posix acls. When posix acls are
> changed it just wants to update its appraisal status to trigger an EVM
> revalidation.
>
> The removal of posix acls is equivalent to passing NULL to the posix set
> acl hooks. This is the same as before through the generic xattr api.
>
> Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
> ---
>
> Notes:
> /* v2 */
> unchanged
>
> /* v3 */
> Paul Moore <paul@paul-moore.com>:
> - Add get, and remove acl hook
>
> /* v4 */
> unchanged
>
> /* v5 */
> Paul Moore <paul@paul-moore.com>:
> - Move ifdef out of function body.
>
> Mimi Zohar <zohar@linux.ibm.com>:
> - Fix details in commit message.
> - Add more details to kernel-doc for evm_inode_set_acl().
>
> include/linux/evm.h | 23 ++++++++
> include/linux/ima.h | 24 ++++++++
> security/integrity/evm/evm_main.c | 83 ++++++++++++++++++++++++++-
> security/integrity/ima/ima_appraise.c | 9 +++
> security/security.c | 21 ++++++-
> 5 files changed, 157 insertions(+), 3 deletions(-)
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
--
paul-moore.com
next prev parent reply other threads:[~2022-10-18 19:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 11:56 [PATCH v5 00/30] acl: add vfs posix acl api Christian Brauner
2022-10-18 11:56 ` [PATCH v5 01/30] orangefs: rework posix acl handling when creating new filesystem objects Christian Brauner
2022-10-18 11:56 ` [PATCH v5 02/30] fs: pass dentry to set acl method Christian Brauner
2022-11-18 10:09 ` Mickaël Salaün
2022-11-18 10:33 ` Christian Brauner
2022-11-18 12:32 ` Mickaël Salaün
2022-10-18 11:56 ` [PATCH v5 03/30] fs: rename current get " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 04/30] fs: add new " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 05/30] cifs: implement " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 06/30] cifs: implement set " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 07/30] 9p: implement get " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 08/30] 9p: implement set " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 09/30] security: add get, remove and set acl hook Christian Brauner
2022-10-18 11:56 ` [PATCH v5 10/30] selinux: implement get, set and remove " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 11/30] smack: " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 12/30] integrity: implement get and set " Christian Brauner
2022-10-18 19:17 ` Paul Moore [this message]
2022-10-18 11:56 ` [PATCH v5 13/30] evm: add post " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 14/30] internal: add may_write_xattr() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 15/30] acl: add vfs_set_acl() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 16/30] acl: add vfs_get_acl() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 17/30] acl: add vfs_remove_acl() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 18/30] ksmbd: use vfs_remove_acl() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 19/30] ecryptfs: implement get acl method Christian Brauner
2022-10-18 11:56 ` [PATCH v5 20/30] ecryptfs: implement set " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 21/30] ovl: implement get " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 22/30] ovl: implement set " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 23/30] ovl: use posix acl api Christian Brauner
2022-10-18 11:56 ` [PATCH v5 24/30] xattr: " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 25/30] evm: remove evm_xattr_acl_change() Christian Brauner
2022-10-18 11:56 ` [PATCH v5 26/30] ecryptfs: use stub posix acl handlers Christian Brauner
2022-10-18 11:56 ` [PATCH v5 27/30] ovl: " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 28/30] cifs: " Christian Brauner
2022-10-18 11:56 ` [PATCH v5 29/30] 9p: " Christian Brauner
2022-10-18 11:57 ` [PATCH v5 30/30] acl: remove a slew of now unused helpers Christian Brauner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAHC9VhSWymFrrV2Zu3isAivuZMvgBxagkoDg3vLGDOww=Y8t_Q@mail.gmail.com' \
--to=paul@paul-moore.com \
--cc=brauner@kernel.org \
--cc=hch@lst.de \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=sforshee@kernel.org \
--cc=viro@zeniv.linux.org.uk \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).