[PATCH] libmbim-glib, proxy: add a configure flag to set the UID of MBIM proxy

[Prathmesh Prabhu]

+aleksander, +dcbw

This is in response to
http://lists.freedesktop.org/archives/libqmi-devel/2014-October/000956.html

On Wed, Nov 5, 2014 at 10:01 AM, Roshan Pius <rpius at chromium.org> wrote:

> Currently, the MBIM proxy process assumes that it is run as root UID and
> that all incoming client connection UIDs are also root.
> However, it's not always preferable to run the MBIM proxy as root for
> security reasons. On some platforms, the MBIM proxy could be constrained
> to run as a less-privileged user and specially granted the permission to
> access the MBIM device. So, adding a compile time flag in libmbim to check
> for the specified UID, rather than assume it to be the root UID. If the
> flag is
> not sent, it'll revert to the existing behaviour of checking for UID=0(i.e
> root)
>
> ---
>  configure.ac                  | 11 +++++++++++
>  src/libmbim-glib/mbim-proxy.c | 11 ++++++-----
>  2 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 27f82c9..132a0d7 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -96,6 +96,17 @@ AC_SUBST(GLIB_MKENUMS)
>  dnl Documentation
>  GTK_DOC_CHECK(1.0)
>
> +# MBIM proxy UID
> +AC_ARG_ENABLE(mbim-proxy-uid,
> +              AS_HELP_STRING([--enable-mbim-proxy-uid=UID], [where mbim
> proxy uid is]),
> +              mbim_proxy_uid=$enableval,
> +              mbim_proxy_uid="")
> +if ! test x"$mbim_proxy_uid" = x""; then
> +  AC_DEFINE_UNQUOTED(MBIM_PROXY_UID, $mbim_proxy_uid, [Define the MBIM
> Proxy UID])
> +else
> +  AC_DEFINE(MBIM_PROXY_UID, 0, [Define the MBIM Proxy UID])
> +fi
> +
>  dnl Man page
>  AC_PATH_PROG(HELP2MAN, help2man, false)
>  AM_CONDITIONAL(BUILDOPT_MAN, test x$HELP2MAN != xfalse)
> diff --git a/src/libmbim-glib/mbim-proxy.c b/src/libmbim-glib/mbim-proxy.c
> index 7677cc6..0cdb05b 100644
> --- a/src/libmbim-glib/mbim-proxy.c
> +++ b/src/libmbim-glib/mbim-proxy.c
> @@ -31,6 +31,7 @@
>  #include <glib/gstdio.h>
>  #include <gio/gunixsocketaddress.h>
>
> +#include "config.h"
>  #include "mbim-device.h"
>  #include "mbim-utils.h"
>  #include "mbim-proxy.h"
> @@ -1060,8 +1061,8 @@ incoming_cb (GSocketService *service,
>          return;
>      }
>
> -    if (uid != 0) {
> -        g_warning ("Client not allowed: Not enough privileges");
> +    if (uid != MBIM_PROXY_UID) {
> +        g_warning ("Client not allowed: Not the expected UID: %u",
> MBIM_PROXY_UID);
>          return;
>      }
>
> @@ -1214,12 +1215,12 @@ mbim_proxy_new (GError **error)
>  {
>      MbimProxy *self;
>
> -    /* Only root can run the mbim-proxy */
> -    if (getuid () != 0) {
> +    /* Only the specified UID can run the mbim-proxy */
> +    if (getuid () != MBIM_PROXY_UID) {
>          g_set_error (error,
>                       MBIM_CORE_ERROR,
>                       MBIM_CORE_ERROR_FAILED,
> -                     "Not enough privileges");
> +                     "Not started with the expected UID: %u",
> MBIM_PROXY_UID);
>          return NULL;
>      }
>
> --
> 2.1.0.rc2.206.gedb03e5
>
> _______________________________________________
> ModemManager-devel mailing list
> ModemManager-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/modemmanager-devel
>



-- 
Regards,
Prathmesh
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