[PATCH 1/2] xen/xsm: Introduce new boot parameter xsm

* [PATCH 1/2] xen/xsm: Introduce new boot parameter xsm
@ 2018-09-29  9:22 Xin Li
  2018-09-29  9:22 ` [PATCH 2/2] xen/xsm: Add new SILO mode for XSM Xin Li
                   ` (2 more replies)
  0 siblings, 3 replies; 27+ messages in thread
From: Xin Li @ 2018-09-29  9:22 UTC (permalink / raw)
  To: xen-devel
  Cc: Sergey Dyasli, Stefano Stabellini, Wei Liu,
	Konrad Rzeszutek Wilk, George Dunlap, Xin Li, Tim Deegan,
	Jan Beulich, Andrew Cooper, Ming Lu, Daniel De Graaf

Introduce new boot parameter xsm to choose which xsm module is enabled,
and set default to dummy.

Signed-off-by: Xin Li <xin.li@citrix.com>

---
CC: Daniel De Graaf <dgdegra@tycho.nsa.gov>
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Jan Beulich <JBeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Tim Deegan <tim@xen.org>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Sergey Dyasli <sergey.dyasli@citrix.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ming Lu <ming.lu@citrix.com>

v4: 
1. change the default XSM boot parameter name from "default" to "dummy".
2. Kconfig, remove XSM_FLASK from EXPERT.
3. Kconfig, add new choice to select the default XSM module.

---
 docs/misc/xen-command-line.markdown | 13 ++++++++
 xen/common/Kconfig                  | 13 +++++++-
 xen/xsm/xsm_core.c                  | 46 ++++++++++++++++++++++++++++-
 3 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index 1ffd586224..cf9924f53f 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -899,6 +899,19 @@ hardware domain is architecture dependent.
 Note that specifying zero as domU value means zero, while for dom0 it means
 to use the default.
 
+### xsm
+> `= dummy | flask`
+
+> Default: `dummy`
+
+Specify which XSM module should be enabled.  This option is only available if
+the hypervisor was compiled with XSM support.
+
+* `dummy`: this is the default choice.  Basic restriction for common deployment
+  (the dummy module) will be applied.  it's also used when XSM is compiled out.
+* `flask`: this is the policy based access control.  To choose this, the
+  separated option in kconfig must also be enabled.
+
 ### flask
 > `= permissive | enforcing | late | disabled`
 
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index 1a6d6281c1..f802efb625 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -116,7 +116,7 @@ config XSM
 
 config XSM_FLASK
 	def_bool y
-	prompt "FLux Advanced Security Kernel support" if EXPERT = "y"
+	prompt "FLux Advanced Security Kernel support"
 	depends on XSM
 	---help---
 	  Enables FLASK (FLux Advanced Security Kernel) as the access control
@@ -154,6 +154,17 @@ config XSM_FLASK_POLICY
 
 	  If unsure, say Y.
 
+choice
+	prompt "Default XSM implementation"
+	depends on XSM
+	default XSM_FLASK_DEFAULT if XSM_FLASK
+	default XSM_DUMMY_DEFAULT
+	config XSM_DUMMY_DEFAULT
+		bool "Match non-XSM behavior"
+	config XSM_FLASK_DEFAULT
+		bool "FLux Advanced Security Kernel" if XSM_FLASK
+endchoice
+
 config LATE_HWDOM
 	bool "Dedicated hardware domain"
 	default n
diff --git a/xen/xsm/xsm_core.c b/xen/xsm/xsm_core.c
index 9645e244c3..df284ec463 100644
--- a/xen/xsm/xsm_core.c
+++ b/xen/xsm/xsm_core.c
@@ -31,6 +31,37 @@
 
 struct xsm_operations *xsm_ops;
 
+enum xsm_bootparam {
+    XSM_BOOTPARAM_DUMMY,
+    XSM_BOOTPARAM_FLASK,
+};
+
+static enum xsm_bootparam __initdata xsm_bootparam =
+#ifdef CONFIG_XSM_FLASK_DEFAULT
+    XSM_BOOTPARAM_FLASK;
+#else
+    XSM_BOOTPARAM_DUMMY;
+#endif
+
+static int __init parse_xsm_param(const char *s)
+{
+    int rc = 0;
+
+    if ( !strcmp(s, "dummy") )
+        xsm_bootparam = XSM_BOOTPARAM_DUMMY;
+#ifdef CONFIG_XSM_FLASK
+    else if ( !strcmp(s, "flask") )
+        xsm_bootparam = XSM_BOOTPARAM_FLASK;
+#endif
+    else {
+        printk("XSM: can't parse boot parameter xsm=%s\n", s);
+        rc = -EINVAL;
+    }
+
+    return rc;
+}
+custom_param("xsm", parse_xsm_param);
+
 static inline int verify(struct xsm_operations *ops)
 {
     /* verify the security_operations structure exists */
@@ -57,7 +88,20 @@ static int __init xsm_core_init(const void *policy_buffer, size_t policy_size)
     }
 
     xsm_ops = &dummy_xsm_ops;
-    flask_init(policy_buffer, policy_size);
+
+    switch ( xsm_bootparam )
+    {
+    case XSM_BOOTPARAM_DUMMY:
+        break;
+
+    case XSM_BOOTPARAM_FLASK:
+        flask_init(policy_buffer, policy_size);
+        break;
+
+    default:
+        printk("XSM: Invalid value for xsm= boot parameter\n");
+        break;
+    }
 
     return 0;
 }
-- 
2.18.0


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