[libvirt] [PATCH]lxc: don't mount dir if ownership couldn't be known

[Daniel P. Berrange]

On Tue, Nov 12, 2013 at 07:38:02PM +0800, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> 
> We bind mount some dir from host to guest.
> With userns enabled, if we couldn't know
> the dir's ownership, don't mount it.
> 
> Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> ---
>  src/lxc/lxc_container.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
> index 255c711..92d0a39 100644
> --- a/src/lxc/lxc_container.c
> +++ b/src/lxc/lxc_container.c
> @@ -96,6 +96,8 @@
>  typedef char lxc_message_t;
>  #define LXC_CONTINUE_MSG 'c'
>  
> +#define OVERFLOWUID 65534
> +
>  typedef struct __lxc_child_argv lxc_child_argv_t;
>  struct __lxc_child_argv {
>      virDomainDefPtr config;
> @@ -1073,6 +1075,18 @@ static int lxcContainerMountFSBind(virDomainFSDefPtr fs,
>      if (virAsprintf(&src, "%s%s", srcprefix, fs->src) < 0)
>          goto cleanup;
>  
> +    if (stat(src, &st) < 0) {
> +        virReportSystemError(errno, _("Unable to stat bind source %s"),
> +                             src);
> +        goto cleanup;
> +    } else {
> +        if (OVERFLOWUID == st.st_uid || OVERFLOWUID == st.st_gid)
> +            errno = EPERM;
> +            virReportSystemError(errno, _("Unknown st_uid/st_gid for %s"),
> +                                 fs->src);
> +        goto cleanup;
> +    }
> +
>      if (stat(fs->dst, &st) < 0) {
>          if (errno != ENOENT) {
>              virReportSystemError(errno, _("Unable to stat bind target %s"),

I'm still not clear what actual problem you're trying to solve here.

What is the current behaviour without this patch & why does it need to
be changed ?


Daniel
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