linux-kernel - Re: [PATCH v5 17/23] security: Introduce inode_post_remove

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f79bb72356ca062d3f3b6b00c3694d8f.paul@paul-moore.com>
Date:   Wed, 15 Nov 2023 23:33:50 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Roberto Sassu <roberto.sassu@...weicloud.com>,
        viro@...iv.linux.org.uk, brauner@...nel.org,
        chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de,
        kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com,
        jmorris@...ei.org, serge@...lyn.com, zohar@...ux.ibm.com,
        dmitry.kasatkin@...il.com, dhowells@...hat.com, jarkko@...nel.org,
        stephen.smalley.work@...il.com, eparis@...isplace.org,
        casey@...aufler-ca.com, mic@...ikod.net
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nfs@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        selinux@...r.kernel.org, Roberto Sassu <roberto.sassu@...wei.com>,
        Stefan Berger <stefanb@...ux.ibm.com>
Subject: Re: [PATCH v5 17/23] security: Introduce inode_post_remove_acl hook

On Nov  7, 2023 Roberto Sassu <roberto.sassu@...weicloud.com> wrote:
> 
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the inode_post_remove_acl hook.
> 
> At inode_remove_acl hook, EVM verifies the file's existing HMAC value. At
> inode_post_remove_acl, EVM re-calculates the file's HMAC with the passed
> POSIX ACL removed and other file metadata.
> 
> Other LSMs could similarly take some action after successful POSIX ACL
> removal.
> 
> The new hook cannot return an error and cannot cause the operation to be
> reverted.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
> Acked-by: Casey Schaufler <casey@...aufler-ca.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
>  fs/posix_acl.c                |  1 +
>  include/linux/lsm_hook_defs.h |  2 ++
>  include/linux/security.h      |  8 ++++++++
>  security/security.c           | 17 +++++++++++++++++
>  4 files changed, 28 insertions(+)

...

> diff --git a/security/security.c b/security/security.c
> index d2dbea54a63a..6eb7c9cff1e5 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2413,6 +2413,23 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
>  	return evm_inode_remove_acl(idmap, dentry, acl_name);
>  }
>  
> +/**
> + * security_inode_post_remove_acl() - Update inode security after rm posix acls
> + * @idmap: idmap of the mount
> + * @dentry: file
> + * @acl_name: acl name
> + *
> + * Update inode security data after successfully removing posix acls on
> + * @dentry in @idmap. The posix acls are identified by @acl_name.
> + */
> +void security_inode_post_remove_acl(struct mnt_idmap *idmap,
> +				    struct dentry *dentry, const char *acl_name)
> +{
> +	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +		return;

See previous comments regaring S_PRIVATE checks.

> +	call_void_hook(inode_post_remove_acl, idmap, dentry, acl_name);
> +}
> +
>  /**
>   * security_inode_post_setxattr() - Update the inode after a setxattr operation
>   * @dentry: file
> -- 
> 2.34.1

--
paul-moore.com