[PATCH 3/5] smack: deduplicate xattr setting in smack_inode_init_security()

[Roberto Sassu]

On Mon, 2025-06-16 at 04:07 +0300, Konstantin Andreev wrote:
> Signed-off-by: Konstantin Andreev <andreev at swemel.ru>
> ---
>  security/smack/smack_lsm.c | 54 ++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 26 deletions(-)
> 
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 2d3186e50c62..2b46a2867226 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -981,6 +981,24 @@ smk_rule_transmutes(struct smack_known *subject,
>  	return (may > 0) && (may & MAY_TRANSMUTE);
>  }
>  
> +static int
> +xattr_dupval(struct xattr *xattrs, int *xattr_count,
> +	     const char *name, const void *value, unsigned int vallen)
> +{
> +	struct xattr * const xattr = lsm_get_xattr_slot(xattrs, xattr_count);
> +
> +	if (!xattr)
> +		return 0;
> +
> +	xattr->value = kmemdup(value, vallen, GFP_NOFS);
> +	if (!xattr->value)
> +		return -ENOMEM;
> +
> +	xattr->value_len = vallen;
> +	xattr->name = name;
> +	return 0;
> +}
> +
>  /**
>   * smack_inode_init_security - copy out the smack from an inode
>   * @inode: the newly created inode
> @@ -998,7 +1016,6 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
>  	struct task_smack *tsp = smack_cred(current_cred());
>  	struct inode_smack * const issp = smack_inode(inode);
>  	struct smack_known *dsp = smk_of_inode(dir);
> -	struct xattr *xattr = lsm_get_xattr_slot(xattrs, xattr_count);
>  	bool trans_cred;
>  	bool trans_rule;
>  
> @@ -1017,8 +1034,6 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
>  	 * Mark the inode as changed.
>  	 */
>  	if (trans_cred || (trans_rule && smk_inode_transmutable(dir))) {
> -		struct xattr *xattr_transmute;
> -
>  		/*
>  		 * The caller of smack_dentry_create_files_as()
>  		 * should have overridden the current cred, so the
> @@ -1030,35 +1045,22 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
>  
>  		if (S_ISDIR(inode->i_mode)) {
>  			issp->smk_flags |= SMK_INODE_TRANSMUTE;
> -			xattr_transmute = lsm_get_xattr_slot(xattrs,
> -							     xattr_count);
> -			if (xattr_transmute) {
> -				xattr_transmute->value = kmemdup(TRANS_TRUE,
> -								 TRANS_TRUE_SIZE,
> -								 GFP_NOFS);
> -				if (!xattr_transmute->value)
> -					return -ENOMEM;
>  
> -				xattr_transmute->value_len = TRANS_TRUE_SIZE;
> -				xattr_transmute->name = XATTR_SMACK_TRANSMUTE;
> -			}
> +			if (xattr_dupval(xattrs, xattr_count,
> +				XATTR_SMACK_TRANSMUTE,
> +				TRANS_TRUE,
> +				TRANS_TRUE_SIZE
> +			))

Ok, can also be optimized that way...

Roberto

> +				return -ENOMEM;
>  		}
>  	}
>  
>  	issp->smk_flags |= SMK_INODE_INSTANT;
>  
> -	if (xattr) {
> -		const char *inode_label = issp->smk_inode->smk_known;
> -
> -		xattr->value = kstrdup(inode_label, GFP_NOFS);
> -		if (!xattr->value)
> -			return -ENOMEM;
> -
> -		xattr->value_len = strlen(inode_label);
> -		xattr->name = XATTR_SMACK_SUFFIX;
> -	}
> -
> -	return 0;
> +	return xattr_dupval(xattrs, xattr_count,
> +			    XATTR_SMACK_SUFFIX,
> +			    issp->smk_inode->smk_known,
> +		     strlen(issp->smk_inode->smk_known));
>  }
>  
>  /**