xen: add hypercall for setting parameters at runtime

Add a sysctl hypercall to support setting parameters similar to
command line parameters, but at runtime. The parameters to set are
specified as a string, just like the boot parameters.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/flask/policy/modules/dom0.te b/tools/flask/policy/modules/dom0.te
index d0a4d91ac09f4425b53641862b78f1396933d82c..338caaf41e448ff3409814a3027655d3ac7e9b30 100644 (file)
--- a/tools/flask/policy/modules/dom0.te
+++ b/tools/flask/policy/modules/dom0.te
@@ -16,7 +16,7 @@ allow dom0_t xen_t:xen {
 allow dom0_t xen_t:xen2 {
        resource_op psr_cmt_op psr_cat_op pmu_ctrl get_symbol
        get_cpu_levelling_caps get_cpu_featureset livepatch_op
-       gcov_op
+       gcov_op set_parameter
 };
 
 # Allow dom0 to use all XENVER_ subops that have checks.

diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index ae58a0f65076f8d58206f541e1ce8d8eee1ee05f..a6882d1c9decfb65fd2a222ababd5039eebff0eb 100644 (file)
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -467,6 +467,42 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
             copyback = 1;
         break;
 
+    case XEN_SYSCTL_set_parameter:
+    {
+#define XEN_SET_PARAMETER_MAX_SIZE 1023
+        char *params;
+
+        if ( op->u.set_parameter.pad[0] || op->u.set_parameter.pad[1] ||
+             op->u.set_parameter.pad[2] )
+        {
+            ret = -EINVAL;
+            break;
+        }
+        if ( op->u.set_parameter.size > XEN_SET_PARAMETER_MAX_SIZE )
+        {
+            ret = -E2BIG;
+            break;
+        }
+        params = xmalloc_bytes(op->u.set_parameter.size + 1);
+        if ( !params )
+        {
+            ret = -ENOMEM;
+            break;
+        }
+        if ( copy_from_guest(params, op->u.set_parameter.params,
+                             op->u.set_parameter.size) )
+            ret = -EFAULT;
+        else
+        {
+            params[op->u.set_parameter.size] = 0;
+            ret = runtime_parse(params);
+        }
+
+        xfree(params);
+
+        break;
+    }
+
     default:
         ret = arch_do_sysctl(op, u_sysctl);
         copyback = 0;

diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 9e51af61e1493b15e832af463bc9ea07c26b95f0..7830b987da1e33b4eefe06ccb7c8d90017d9f3f7 100644 (file)
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -1096,6 +1096,24 @@ struct xen_sysctl_livepatch_op {
 typedef struct xen_sysctl_livepatch_op xen_sysctl_livepatch_op_t;
 DEFINE_XEN_GUEST_HANDLE(xen_sysctl_livepatch_op_t);
 
+/*
+ * XEN_SYSCTL_set_parameter
+ *
+ * Change hypervisor parameters at runtime.
+ * The input string is parsed similar to the boot parameters.
+ * Parameters are a single string terminated by a NUL byte of max. size
+ * characters. Multiple settings can be specified by separating them
+ * with blanks.
+ */
+
+struct xen_sysctl_set_parameter {
+    XEN_GUEST_HANDLE_64(char) params;       /* IN: pointer to parameters. */
+    uint16_t size;                          /* IN: size of parameters. */
+    uint16_t pad[3];                        /* IN: MUST be zero. */
+};
+typedef struct xen_sysctl_set_parameter xen_sysctl_set_parameter_t;
+DEFINE_XEN_GUEST_HANDLE(xen_sysctl_set_parameter_t);
+
 struct xen_sysctl {
     uint32_t cmd;
 #define XEN_SYSCTL_readconsole                    1
@@ -1124,6 +1142,7 @@ struct xen_sysctl {
 #define XEN_SYSCTL_get_cpu_levelling_caps        25
 #define XEN_SYSCTL_get_cpu_featureset            26
 #define XEN_SYSCTL_livepatch_op                  27
+#define XEN_SYSCTL_set_parameter                 28
     uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
     union {
         struct xen_sysctl_readconsole       readconsole;
@@ -1152,6 +1171,7 @@ struct xen_sysctl {
         struct xen_sysctl_cpu_levelling_caps cpu_levelling_caps;
         struct xen_sysctl_cpu_featureset    cpu_featureset;
         struct xen_sysctl_livepatch_op      livepatch;
+        struct xen_sysctl_set_parameter     set_parameter;
         uint8_t                             pad[128];
     } u;
 };

diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 61cd98533b1e3a905a8673be8773de314b174a55..56dc5b0ab947d6ccbaf9f5a8501350b3a4c60d02 100644 (file)
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -828,6 +828,9 @@ static int flask_sysctl(int cmd)
     case XEN_SYSCTL_gcov_op:
         return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
                                     XEN2__GCOV_OP, NULL);
+    case XEN_SYSCTL_set_parameter:
+        return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
+                                    XEN2__SET_PARAMETER, NULL);
 
     default:
         return avc_unknown_permission("sysctl", cmd);

diff --git a/xen/xsm/flask/policy/access_vectors b/xen/xsm/flask/policy/access_vectors
index f276f04e29752ea54473c67e71d2e2fbec78fa89..da9f3dfb2ecb6247e2a49397abf7c7c647de3844 100644 (file)
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -101,6 +101,8 @@ class xen2
     livepatch_op
 # XEN_SYSCTL_gcov_op
     gcov_op
+# XEN_SYSCTL_set_parameter
+    set_parameter
 }
 
 # Classes domain and domain2 consist of operations that a domain performs on