linux-kernel - Re: [PATCH v5 1/6] reiserfs: Switch to security_inode_init

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Date:   Wed, 23 Nov 2022 08:12:27 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...weicloud.com>, mark@...heh.com,
        jlbec@...lplan.org, joseph.qi@...ux.alibaba.com,
        dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, stephen.smalley.work@...il.com,
        eparis@...isplace.org, casey@...aufler-ca.com
Cc:     ocfs2-devel@....oracle.com, reiserfs-devel@...r.kernel.org,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
        linux-kernel@...r.kernel.org, keescook@...omium.org,
        nicolas.bouchinet@...p-os.org,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [PATCH v5 1/6] reiserfs: Switch to
 security_inode_init_security()

On Wed, 2022-11-23 at 10:51 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
> 
> In preparation for removing security_old_inode_init_security(), switch to
> security_inode_init_security().
> 
> Define the initxattrs callback reiserfs_initxattrs(), to populate the
> name/value/len triple in the reiserfs_security_handle() with the first
> xattr provided by LSMs. Multiple xattrs are currently not supported, as the
> reiserfs_security_handle structure is exported to user space.

The security_old_inode_init_security() hook doesn't support EVM. 
Missing from this patch description is whether the move to the
security_inode_init_security() hook changes security.evm.  FYI, I'm not
suggesting it should.  Please update the patch description accordingly.

Mimi

> 
> In reiserfs_initxattrs(), make a copy of the first xattr value, as
> security_inode_init_security() frees it.
> 
> After the call to security_inode_init_security(), remove the check for
> returning -EOPNOTSUPP, as security_inode_init_security() changes it to
> zero.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> ---
>  fs/reiserfs/xattr_security.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/reiserfs/xattr_security.c b/fs/reiserfs/xattr_security.c
> index 857a65b05726..0ba96757681d 100644
> --- a/fs/reiserfs/xattr_security.c
> +++ b/fs/reiserfs/xattr_security.c
> @@ -39,6 +39,22 @@ static bool security_list(struct dentry *dentry)
>  	return !IS_PRIVATE(d_inode(dentry));
>  }
>  
> +static int
> +reiserfs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
> +		    void *fs_info)
> +{
> +	struct reiserfs_security_handle *sec = fs_info;
> +
> +	sec->value = kmemdup(xattr_array->value, xattr_array->value_len,
> +			     GFP_KERNEL);
> +	if (!sec->value)
> +		return -ENOMEM;
> +
> +	sec->name = xattr_array->name;
> +	sec->length = xattr_array->value_len;
> +	return 0;
> +}
> +
>  /* Initializes the security context for a new inode and returns the number
>   * of blocks needed for the transaction. If successful, reiserfs_security
>   * must be released using reiserfs_security_free when the caller is done. */
> @@ -56,12 +72,9 @@ int reiserfs_security_init(struct inode *dir, struct inode *inode,
>  	if (IS_PRIVATE(dir))
>  		return 0;
>  
> -	error = security_old_inode_init_security(inode, dir, qstr, &sec->name,
> -						 &sec->value, &sec->length);
> +	error = security_inode_init_security(inode, dir, qstr,
> +					     &reiserfs_initxattrs, sec);
>  	if (error) {
> -		if (error == -EOPNOTSUPP)
> -			error = 0;
> -
>  		sec->name = NULL;
>  		sec->value = NULL;
>  		sec->length = 0;