linux-kernel - Re: [PATCH 3/7] SLIM main patch

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]

Date:	Wed, 23 Aug 2006 15:27:33 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Kylene Jo Hall <kjhall@...ibm.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	LSM ML <linux-security-module@...r.kernel.org>,
	Dave Safford <safford@...ibm.com>,
	Mimi Zohar <zohar@...ibm.com>, Serge Hallyn <sergeh@...ibm.com>
Subject: Re: [PATCH 3/7] SLIM main patch

On Wed, Aug 23, 2006 at 12:05:37PM -0700, Kylene Jo Hall wrote:
> +/* 
> + * Called with current->files->file_lock. There is not a great lock to grab
> + * for demotion of this type.  The only place f_mode is changed after install
> + * is in mark_files_ro in the filesystem code.  That function is also changing
> + * taking away write rights so even if we race the outcome is the same.
> + */
> +static inline void do_revoke_file_wperm(struct file *file,
> +					struct slm_file_xattr *cur_level)
> +{
> +	struct inode *inode;
> +	struct slm_isec_data *isec;
> +
> +	inode = file->f_dentry->d_inode;
> +	if (!S_ISREG(inode->i_mode) || !(file->f_mode && FMODE_WRITE))
> +		return;
> +
> +	isec = inode->i_security;
> +	spin_lock(&isec->lock);
> +	if (is_lower_integrity(cur_level, &isec->level))
> +		file->f_mode &= ~FMODE_WRITE;
> +	spin_unlock(&isec->lock);
> +}

This function does not do what you claim or hope it is supposed to do.  
Looking at the races (you do nothing to shoot down writes that are in 
progress) present, this does not instill confidence in the rest of the 
code (as always seems to be the case with new security frameworks or 
patches).  Cheers,

		-ben
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/