On Fri, May 10, 2013 at 05:58:13PM +0800, Gao feng wrote:
> This patch introduces new helper function
> virLXCControllerSetupUserns, in this function,
> we set the files uid_map and gid_map of the init
> task of container.
>
> lxcContainerSetUserns is used for creating cred for
> tasks running in container. Since after setuid/setgid,
> we may be a new user. This patch calls lxcContainerSetUserns
> at first to make sure the new created files belong to
> right user.
>
> Signed-off-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
> ---
> src/lxc/lxc_container.c | 59 +++++++++++++++++++++++++++-------------
> src/lxc/lxc_controller.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 111 insertions(+), 18 deletions(-)
>
> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
> index 094f205..eabaa34 100644
> --- a/src/lxc/lxc_container.c
> +++ b/src/lxc/lxc_container.c
> @@ -331,6 +331,26 @@ int lxcContainerWaitForContinue(int control)
>
>
> /**
> + * lxcContainerSetUserns:
> + *
> + * This function calls setuid and setgid to create proper
> + * cred for tasks running in container.
> + *
> + * Returns 0 on success or -1 in case of error
> + */
> +static int lxcContainerSetUserns(virDomainDefPtr def)
I think it'd be better named as s/lxcContainerSetUserns/lxcContainerSetID/
> +{
> + if (def->idmap.nuidmap && def->idmap.ngidmap && virSetUIDGID(0, 0) < 0) {
This doesn't do the right thing if "nuidmap > 0 && ngidmap == 0"
or vica-verca. Better to write it as
uid_t uid = (uid_t)-1;
gid_t gid = (gid_t)-1;
if (def->idmap.nuidmap)
uid = 0;
if (def->idmap.ngidmap)
gid = 0;
if ((def->idmap.nuidmap || def->idmap.ngidmap) &&
virSetUIDGID(uid, gid) < 0) {
...error...
}
(virSetUIDGID accepts -1 as meaning don't change that id)
> diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
> index 8c358c3..e9b90bf 100644
> --- a/src/lxc/lxc_controller.c
> +++ b/src/lxc/lxc_controller.c
> @@ -1036,6 +1036,73 @@ cleanup2:
> }
>
>
> +static int virLXCControllerSetupUsernsMap(struct idmap *map,
> + char *path,
> + int num)
> +{
> + char *map_value = NULL;
> + int i, ret = -1;
> +
> + for (i = 0; i < num; i++) {
> + if (virAsprintf(&map_value, "%s %u %u %u\n",
> + map_value ? map_value : "",
> + map[i].start, map[i].target, map[i].count) < 0)
> + goto cleanup;
> + }
You're leaking memory on every iteration of this loop by ovewriting
the map_value pointer each time. You should use the virBuffer APIs
to build up a string incrementally.
> +
> + if (virFileWriteStr(path, map_value, 0) < 0) {
> + if (errno == -ENOENT)
> + virReportSystemError(errno,
> + _("%s doesn't exist, please disable userns"),
> + path);
This special errno check shouldn't be required if your earlier
check for existance of user ns is correctly called.
> + virReportSystemError(errno, _("unable write to %s"), path);
> + goto cleanup;
> + }
> + ret = 0;
> +
> +cleanup:
> + VIR_FREE(map_value);
> + return ret;
> +}
> +
> +/**
> + * virLXCControllerSetupUserns
> + *
> + * Set proc files for user namespace
> + *
> + * Returns 0 on success or -1 in case of error
> + */
> +static int virLXCControllerSetupUserns(virLXCControllerPtr ctrl)
> +{
> + char *uid_map = NULL;
> + char *gid_map = NULL;
> + int ret = -1;
> +
> + if (ctrl->def->idmap.nuidmap == 0 || ctrl->def->idmap.ngidmap == 0)
> + return 0;
This implies that the user must supply both a UID map and a GID map
or neither. If it is an error to provide one and not the other, then
this is something you should enforce during parsing.
> +
> + if (virAsprintf(&uid_map, "/proc/%d/uid_map", ctrl->initpid) < 0)
> + goto cleanup;
> +
> + if (virLXCControllerSetupUsernsMap(ctrl->def->idmap.uidmap, uid_map,
> + ctrl->def->idmap.nuidmap) < 0)
> + goto cleanup;
> +
> + if (virAsprintf(&gid_map, "/proc/%d/gid_map", ctrl->initpid) < 0)
> + goto cleanup;
> +
> + if (virLXCControllerSetupUsernsMap(ctrl->def->idmap.gidmap, gid_map,
> + ctrl->def->idmap.ngidmap) < 0)
> + goto cleanup;
> +
> + ret = 0;
> +cleanup:
> + VIR_FREE(uid_map);
> + VIR_FREE(gid_map);
> + return ret;
> +}
Daniel
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