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From: Richard Guy Briggs <rgb@redhat.com>
To: Paul Moore <pmoore@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-audit@redhat.com,
	sd@queasysnail.net, linux-kernel@vger.kernel.org,
	linux@roeck-us.net, viro@zeniv.linux.org.uk
Subject: Re: [PATCH v2 1/5] fs: rework getname_kernel to handle up to PATH_MAX sized filenames
Date: Thu, 22 Jan 2015 10:53:16 -0500	[thread overview]
Message-ID: <20150122155316.GH18752@madcap2.tricolour.ca> (raw)
In-Reply-To: <20150122045956.1347.11508.stgit@localhost>

On 15/01/21, Paul Moore wrote:
> In preparation for expanded use in the kernel, make getname_kernel()
> more useful by allowing it to handle any legal filename length.
> 
> Thanks to Guenter Roeck for his suggestion to substitute memcpy() for
> strlcpy().
> 
> CC: linux@roeck-us.net
> CC: viro@zeniv.linux.org.uk
> CC: linux-fsdevel@vger.kernel.org
> Signed-off-by: Paul Moore <pmoore@redhat.com>

Noted memcpy() difference (I assume to avoid races).

Reviewed-by: Richard Guy Briggs <rgb@redhat.com>

> ---
>  fs/namei.c |   34 ++++++++++++++++++++--------------
>  1 file changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 9eb787e..63eaaf6 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -211,32 +211,38 @@ getname(const char __user * filename)
>  	return getname_flags(filename, 0, NULL);
>  }
>  
> -/*
> - * The "getname_kernel()" interface doesn't do pathnames longer
> - * than EMBEDDED_NAME_MAX. Deal with it - you're a kernel user.
> - */
>  struct filename *
>  getname_kernel(const char * filename)
>  {
>  	struct filename *result;
> -	char *kname;
> -	int len;
> -
> -	len = strlen(filename);
> -	if (len >= EMBEDDED_NAME_MAX)
> -		return ERR_PTR(-ENAMETOOLONG);
> +	int len = strlen(filename) + 1;
>  
>  	result = __getname();
>  	if (unlikely(!result))
>  		return ERR_PTR(-ENOMEM);
>  
> -	kname = (char *)result + sizeof(*result);
> -	result->name = kname;
> +	if (len <= EMBEDDED_NAME_MAX) {
> +		result->name = (char *)(result) + sizeof(*result);
> +		result->separate = false;
> +	} else if (len <= PATH_MAX) {
> +		struct filename *tmp;
> +
> +		tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
> +		if (unlikely(!tmp)) {
> +			__putname(result);
> +			return ERR_PTR(-ENOMEM);
> +		}
> +		tmp->name = (char *)result;
> +		tmp->separate = true;
> +		result = tmp;
> +	} else {
> +		__putname(result);
> +		return ERR_PTR(-ENAMETOOLONG);
> +	}
> +	memcpy((char *)result->name, filename, len);
>  	result->uptr = NULL;
>  	result->aname = NULL;
> -	result->separate = false;
>  
> -	strlcpy(kname, filename, EMBEDDED_NAME_MAX);
>  	return result;
>  }
>  
> 

- RGB

--
Richard Guy Briggs <rbriggs@redhat.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

  reply	other threads:[~2015-01-22 15:53 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-22  4:59 [PATCH v2 0/5] Overhaul the audit filename handling Paul Moore
2015-01-22  4:59 ` [PATCH v2 1/5] fs: rework getname_kernel to handle up to PATH_MAX sized filenames Paul Moore
2015-01-22 15:53   ` Richard Guy Briggs [this message]
2015-01-22 16:56     ` Guenter Roeck
2015-01-22  5:00 ` [PATCH v2 2/5] fs: create proper filename objects using getname_kernel() Paul Moore
2015-01-22 15:54   ` Richard Guy Briggs
2015-01-22  5:00 ` [PATCH v2 3/5] audit: enable filename recording via getname_kernel() Paul Moore
2015-01-22  5:00 ` [PATCH v2 4/5] audit: fix filename matching in __audit_inode() and __audit_inode_child() Paul Moore
2015-01-22 16:04   ` Richard Guy Briggs
2015-01-22  5:00 ` [PATCH v2 5/5] audit: replace getname()/putname() hacks with reference counters Paul Moore
2015-01-22 16:09   ` Richard Guy Briggs
2015-01-22 16:24     ` Paul Moore
2015-01-22  5:36 ` [PATCH v2 0/5] Overhaul the audit filename handling Guenter Roeck
2015-01-22  7:54   ` Al Viro
2015-01-22 16:23     ` Paul Moore
2015-01-22 21:25       ` Paul Moore
2015-01-22 21:29         ` Al Viro
2015-01-22 21:40           ` Al Viro
2015-01-22 22:05             ` Paul Moore
2015-01-23  5:30             ` Al Viro
2015-01-23 16:15               ` Paul Moore
2015-01-24  9:03               ` Sedat Dilek
2015-01-24 22:54                 ` Stephen Rothwell
2015-01-26 15:52                 ` Paul Moore
2015-01-22 17:13     ` Guenter Roeck
2015-01-22 16:22   ` Paul Moore
2015-01-22 16:58     ` Guenter Roeck

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