linux-kernel - Re: [PATCH v2 4/6] LSM: lsm_context in security_dentry_init

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Message-ID: <b94aa34a25a19ea729faa1c8240ebf5b@paul-moore.com>
Date: Mon, 21 Oct 2024 19:39:49 -0400
From: Paul Moore <paul@...l-moore.com>
To: Casey Schaufler <casey@...aufler-ca.com>, casey@...aufler-ca.com, linux-security-module@...r.kernel.org
Cc: jmorris@...ei.org, serge@...lyn.com, keescook@...omium.org, john.johansen@...onical.com, penguin-kernel@...ove.sakura.ne.jp, stephen.smalley.work@...il.com, linux-kernel@...r.kernel.org, selinux@...r.kernel.org, mic@...ikod.net, ceph-devel@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [PATCH v2 4/6] LSM: lsm_context in security_dentry_init_security

On Oct 14, 2024 Casey Schaufler <casey@...aufler-ca.com> wrote:
> 
> Replace the (secctx,seclen) pointer pair with a single lsm_context
> pointer to allow return of the LSM identifier along with the context
> and context length. This allows security_release_secctx() to know how
> to release the context. Callers have been modified to use or save the
> returned data from the new structure.
> 
> Special care is taken in the NFS code, which uses the same data structure
> for its own copied labels as it does for the data which comes from
> security_dentry_init_security().  In the case of copied labels the data
> has to be freed, not released.
> 
> The scaffolding funtion lsmcontext_init() is no longer needed and is
> removed.
> 
> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
> Cc: ceph-devel@...r.kernel.org
> Cc: linux-nfs@...r.kernel.org
> ---
>  fs/ceph/super.h               |  3 +--
>  fs/ceph/xattr.c               | 16 ++++++----------
>  fs/fuse/dir.c                 | 35 ++++++++++++++++++-----------------
>  fs/nfs/dir.c                  |  2 +-
>  fs/nfs/inode.c                | 17 ++++++++++-------
>  fs/nfs/internal.h             |  8 +++++---
>  fs/nfs/nfs4proc.c             | 22 +++++++++-------------
>  fs/nfs/nfs4xdr.c              | 22 ++++++++++++----------
>  include/linux/lsm_hook_defs.h |  2 +-
>  include/linux/nfs4.h          |  8 ++++----
>  include/linux/nfs_fs.h        |  2 +-
>  include/linux/security.h      | 26 +++-----------------------
>  security/security.c           |  9 ++++-----
>  security/selinux/hooks.c      |  9 +++++----
>  14 files changed, 80 insertions(+), 101 deletions(-)

...

> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 039898d70954..47652d217d05 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -457,7 +457,7 @@ static inline void nfs4_label_free(struct nfs4_label *label)
>  {
>  #ifdef CONFIG_NFS_V4_SECURITY_LABEL
>  	if (label) {
> -		kfree(label->label);
> +		kfree(label->lsmctx.context);

Shouldn't this be a call to security_release_secctx() instead of a raw
kfree()?

>  		kfree(label);
>  	}
>  #endif

--
paul-moore.com