Re: [PATCH v1 1/4] xsm/libxl/xen_version: Add XSM for some of the xen_version commands.

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 09/10/15 03:56, Konrad Rzeszutek Wilk wrote:
> The XENVER_[compile_info|changeset|commandline] are now
> guarded by an XSM check.
>
> The rest: XENVER_[version|extraversion|capabilities|
> parameters|get_features|page_size|guest_handle] behave
> as before (no XSM check).
>
> We allow the initial domain to see these while the other
> guests are not permitted.
>
> As such we also modify the toolstack such that if we fail
> to get any data instead of printing (null) we just print "".
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  tools/flask/policy/policy/modules/xen/xen.te |  2 +-
>  tools/libxl/libxl.c                          |  3 +++
>  xen/common/kernel.c                          | 11 ++++++++++-
>  xen/include/xsm/dummy.h                      | 24 ++++++++++++++++++++++++
>  xen/include/xsm/xsm.h                        |  6 ++++++
>  xen/xsm/dummy.c                              |  1 +
>  xen/xsm/flask/hooks.c                        | 25 +++++++++++++++++++++++++
>  xen/xsm/flask/policy/access_vectors          |  2 ++
>  8 files changed, 72 insertions(+), 2 deletions(-)
>
> diff --git a/tools/flask/policy/policy/modules/xen/xen.te b/tools/flask/policy/policy/modules/xen/xen.te
> index d35ae22..d0ad758 100644
> --- a/tools/flask/policy/policy/modules/xen/xen.te
> +++ b/tools/flask/policy/policy/modules/xen/xen.te
> @@ -86,7 +86,7 @@ allow dom0_t dom0_t:domain {
>  };
>  allow dom0_t dom0_t:domain2 {
>  	set_cpuid gettsc settsc setscheduler set_max_evtchn set_vnumainfo
> -	get_vnumainfo psr_cmt_op psr_cat_op
> +	get_vnumainfo psr_cmt_op psr_cat_op version_use
>  };
>  allow dom0_t dom0_t:resource { add remove };
>  
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 22bbc29..efa6462 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -5272,6 +5272,7 @@ const libxl_version_info* libxl_get_version_info(libxl_ctx *ctx)
>      xc_version(ctx->xch, XENVER_extraversion, &u.xen_extra);
>      info->xen_version_extra = strdup(u.xen_extra);
>  
> +    memset(&u.xen_cc, 0, sizeof(xen_compile_info_t));

FILLZERO()

>      xc_version(ctx->xch, XENVER_compile_info, &u.xen_cc);
>      info->compiler = strdup(u.xen_cc.compiler);
>      info->compile_by = strdup(u.xen_cc.compile_by);
> @@ -5281,6 +5282,7 @@ const libxl_version_info* libxl_get_version_info(libxl_ctx *ctx)
>      xc_version(ctx->xch, XENVER_capabilities, &u.xen_caps);
>      info->capabilities = strdup(u.xen_caps);
>  
> +    memset(&u.xen_cc, 0, sizeof(xen_changeset_info_t));
>      xc_version(ctx->xch, XENVER_changeset, &u.xen_chgset);
>      info->changeset = strdup(u.xen_chgset);
>  
> @@ -5289,6 +5291,7 @@ const libxl_version_info* libxl_get_version_info(libxl_ctx *ctx)
>  
>      info->pagesize = xc_version(ctx->xch, XENVER_pagesize, NULL);
>  
> +    memset(&u.xen_commandline, 0, sizeof(xen_commandline_t));
>      xc_version(ctx->xch, XENVER_commandline, &u.xen_commandline);
>      info->commandline = strdup(u.xen_commandline);
>  
> diff --git a/xen/common/kernel.c b/xen/common/kernel.c
> index 6a3196a..210ec99 100644
> --- a/xen/common/kernel.c
> +++ b/xen/common/kernel.c
> @@ -13,6 +13,7 @@
>  #include <xen/nmi.h>
>  #include <xen/guest_access.h>
>  #include <xen/hypercall.h>
> +#include <xsm/xsm.h>
>  #include <asm/current.h>
>  #include <public/nmi.h>
>  #include <public/version.h>
> @@ -226,9 +227,17 @@ void __init do_initcalls(void)
>  /*
>   * Simple hypercalls.
>   */
> -
> +#define XENVER_CMD_XSM_CHECK    ( (1U << XENVER_compile_info) | \
> +                                  (1U << XENVER_changeset) | \
> +                                  (1U << XENVER_commandline) )
>  DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
>  {
> +    if ( ( 1 << cmd ) & XENVER_CMD_XSM_CHECK )
> +    {
> +        int rc = xsm_version_op(XSM_PRIV, cmd);
> +        if ( rc )
> +            return rc;

This call should be unconditional.  It is not going to make a
measureable difference on XENVER_version latency.

~Andrew