[lxc-devel] [PATCH] lxc.rootfs: support multiple lower layers

Serge Hallyn serge.hallyn at ubuntu.com
Sat Jan 23 07:13:11 UTC 2016


Quoting Christian Brauner (christianvanbrauner at gmail.com):
> Do it in a safe way by using strstr() to check for the substring ":/" should
> ':' be part of a pathname. This should be a safer implementation than the one
> originally suggested in #547.
> 
> Signed-off-by: Christian Brauner <christian.brauner at mailbox.org>

Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

> ---
>  src/lxc/bdev/lxcoverlay.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/src/lxc/bdev/lxcoverlay.c b/src/lxc/bdev/lxcoverlay.c
> index d06d24f..5ffc289 100644
> --- a/src/lxc/bdev/lxcoverlay.c
> +++ b/src/lxc/bdev/lxcoverlay.c
> @@ -309,7 +309,7 @@ char *ovl_getlower(char *p)
>  
>  int ovl_mount(struct bdev *bdev)
>  {
> -	char *options, *dup, *lower, *upper;
> +	char *tmp, *options, *dup, *lower, *upper;
>  	char *options_work, *work, *lastslash;
>  	int lastslashidx;
>  	int len, len2;
> @@ -331,9 +331,15 @@ int ovl_mount(struct bdev *bdev)
>  	 */
>  	dup = alloca(strlen(bdev->src) + 1);
>  	strcpy(dup, bdev->src);
> -	if (!(lower = strchr(dup, ':')))
> -		return -22;
> -	if (!(upper = strchr(++lower, ':')))
> +	/* support multiple lower layers */
> +	if (!(lower = strstr(dup, ":/")))
> +			return -22;
> +	lower++;
> +	upper = lower;
> +	while ((tmp = strstr(++upper, ":/"))) {
> +		upper = tmp;
> +	}
> +	if (--upper == lower)
>  		return -22;
>  	*upper = '\0';
>  	upper++;
> -- 
> 2.7.0
> 
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