libxc: Provide access to internal handles

In order to support auditing of qemu depriv, my audit tool wants to
know the fd of a privcmd handle on which it can easily make
hypercalls.  xencall provides such a handle, but has no cooked
facilities for making hypercalls.  So I open a libxc handle.  That
means I need to get the privcmd fd out of the libxc handle.

ISTM that it is best to do this by providing an interface to get the
underlying library handles for a libxc handle.  This kind of interface
is quite common elsewhere and has not caused problems.

libxc is not a stable API so the downside risk of providing this
access is not significant.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 580d2cdb0692274fd43af4ea1468b26d5106885f..5520c942d104370bad954c4f43084f23abef8ac3 100644 (file)
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -183,6 +183,16 @@ enum xc_open_flags {
  */
 int xc_interface_close(xc_interface *xch);
 
+/**
+ * Return the handles which xch has opened and will use for
+ * hypercalls, foreign memory accesses and device model operations.
+ * These may be used with the corresponding libraries so long as the
+ * xch itself remains open.
+ */
+struct xencall_handle *xc_interface_xcall_handle(xc_interface *xch);
+struct xenforeignmemory_handle *xc_interface_fmem_handle(xc_interface *xch);
+struct xendevicemodel_handle *xc_interface_dmod_handle(xc_interface *xch);
+
 /*
  * HYPERCALL SAFE MEMORY BUFFER
  *

diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index e6e3d9913c132ba326098b149f2ed56006f782c8..90974d572e27956268ee8e51b25bbafa05432f90 100644 (file)
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -104,6 +104,21 @@ int xc_interface_close(xc_interface *xch)
     return rc;
 }
 
+xencall_handle *xc_interface_xcall_handle(xc_interface *xch)
+{
+    return xch->xcall;
+}
+
+struct xenforeignmemory_handle *xc_interface_fmem_handle(xc_interface *xch)
+{
+    return xch->fmem;
+}
+
+struct xendevicemodel_handle *xc_interface_dmod_handle(xc_interface *xch)
+{
+    return xch->dmod;
+}
+
 static pthread_key_t errbuf_pkey;
 static pthread_once_t errbuf_pkey_once = PTHREAD_ONCE_INIT;