On Fri, Aug 09, 2013 at 04:05:58PM +0800, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx>
>
> If we enable userns, the ownership of dir we provided for containers
> should match the uid/gid in idmap.
> Currently, the debug log is very implicit or misleading sometimes.
> This patch will help clarify this for us when using
> debug log or virsh.
>
> v2: syntax-check clean
>
> Signed-off-by: Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx>
> ---
> src/lxc/lxc_container.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 46 insertions(+), 0 deletions(-)
>
> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
> index b910b10..2ccdc61 100644
> --- a/src/lxc/lxc_container.c
> +++ b/src/lxc/lxc_container.c
> @@ -1815,6 +1815,49 @@ lxcNeedNetworkNamespace(virDomainDefPtr def)
> return false;
> }
>
> +/*
> + * Helper function for helping check
> + * whether we have enough privilege
> + * to operate the source dir when userns enabled
> + * @vmDef: pointer to vm definition structure
> + * Returns 0 on success or -1 in case of error
> + */
> +static int
> +lxcContainerUsernsSrcOwnershipCheck(virDomainDefPtr vmDef)
> +{
> + struct stat buf;
> + size_t i;
> + uid_t uid;
> + gid_t gid;
> +
> + VIR_DEBUG("vmDef->nfss %d", (int)vmDef->nfss);
> + for (i = 0; i < vmDef->nfss; i++) {
> + VIR_DEBUG("dst is %s, src is %s",
> + vmDef->fss[i]->dst,
> + vmDef->fss[i]->src);
> +
> + uid = vmDef->idmap.uidmap[0].target;
> + gid = vmDef->idmap.gidmap[0].target;
> +
> + if (lstat(vmDef->fss[i]->src, &buf) < 0) {
> + virReportSystemError(errno, _("Cannot access '%s'"),
> + vmDef->fss[i]->src);
> + return -1;
> + } else if (uid != buf.st_uid || gid != buf.st_gid) {
Comparing the uid/gid owner of a file is not an accurate check.
For example, a file could have ACLs set which allow access even
when the uid/gid do not match.
I think we should focus on improving the error messages reported
when we hit the actual problem rather than trying to pre-guess the
problem and potentially get it wrong.
Daniel
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