linux-kernel - Re: [PATCH V6 4/4] audit: avoid double copying the audit

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Message-ID: <20150717020128.GF32473@madcap2.tricolour.ca>
Date:	Thu, 16 Jul 2015 22:01:28 -0400
From:	Richard Guy Briggs <rgb@...hat.com>
To:	Paul Moore <pmoore@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	sgrubb@...hat.com, eparis@...hat.com, pmoody@...gle.com
Subject: Re: [PATCH V6 4/4] audit: avoid double copying the audit_exe path
 string

On 15/07/16, Paul Moore wrote:
> On Tuesday, July 14, 2015 11:50:26 AM Richard Guy Briggs wrote:
> > Make this interface consistent with watch and filter key, avoiding the extra
> > string copy and simply consume the new string pointer.
> > 
> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > ---
> >  kernel/audit_exe.c      |    8 ++++++--
> >  kernel/audit_fsnotify.c |    9 +--------
> >  kernel/auditfilter.c    |    2 +-
> >  3 files changed, 8 insertions(+), 11 deletions(-)
> 
> Merge this patch too, there is no reason why these needs to be its own patch.

I wanted to keep this patch seperate until it is well understood and
accepted rather than mix it in.

I'm fine merging it if you prefer.

> > diff --git a/kernel/audit_exe.c b/kernel/audit_exe.c
> > index 75ad4f2..09e4eb4 100644
> > --- a/kernel/audit_exe.c
> > +++ b/kernel/audit_exe.c
> > @@ -27,11 +27,15 @@ int audit_dupe_exe(struct audit_krule *new, struct
> > audit_krule *old) struct audit_fsnotify_mark *audit_mark;
> >  	char *pathname;
> > 
> > -	pathname = audit_mark_path(old->exe);
> > +	pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL);
> > +	if (!pathname)
> > +		return -ENOMEM;
> > 
> >  	audit_mark = audit_alloc_mark(new, pathname, strlen(pathname));
> > -	if (IS_ERR(audit_mark))
> > +	if (IS_ERR(audit_mark)) {
> > +		kfree(pathname);
> >  		return PTR_ERR(audit_mark);
> > +	}
> >  	new->exe = audit_mark;
> > 
> >  	return 0;
> > diff --git a/kernel/audit_fsnotify.c b/kernel/audit_fsnotify.c
> > index a4e7b16..e57e08a 100644
> > --- a/kernel/audit_fsnotify.c
> > +++ b/kernel/audit_fsnotify.c
> > @@ -94,7 +94,6 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct
> > audit_krule *krule, char *pa struct dentry *dentry;
> >  	struct inode *inode;
> >  	unsigned long ino;
> > -	char *local_pathname;
> >  	dev_t dev;
> >  	int ret;
> > 
> > @@ -115,21 +114,15 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct
> > audit_krule *krule, char *pa ino = dentry->d_inode->i_ino;
> >  	}
> > 
> > -	audit_mark = ERR_PTR(-ENOMEM);
> > -	local_pathname = kstrdup(pathname, GFP_KERNEL);
> > -	if (!local_pathname)
> > -		goto out;
> > -
> >  	audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
> >  	if (unlikely(!audit_mark)) {
> > -		kfree(local_pathname);
> >  		audit_mark = ERR_PTR(-ENOMEM);
> >  		goto out;
> >  	}
> > 
> >  	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_free_mark);
> >  	audit_mark->mark.mask = AUDIT_FS_EVENTS;
> > -	audit_mark->path = local_pathname;
> > +	audit_mark->path = pathname;
> >  	audit_mark->ino = ino;
> >  	audit_mark->dev = dev;
> >  	audit_mark->rule = krule;
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index f65c97f..f46ed69 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -559,8 +559,8 @@ static struct audit_entry *audit_data_to_entry(struct
> > audit_rule_data *data, entry->rule.buflen += f->val;
> > 
> >  			audit_mark = audit_alloc_mark(&entry->rule, str, f->val);
> > -			kfree(str);
> >  			if (IS_ERR(audit_mark)) {
> > +				kfree(str);
> >  				err = PTR_ERR(audit_mark);
> >  				goto exit_free;
> >  			}
> 
> -- 
> paul moore
> security @ redhat
> 

- RGB

--
Richard Guy Briggs <rbriggs@...hat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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