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linux: prevent non-Xen modules from loading in Xen kernel

PATCH In review Jan Beulich 3 participants 6 messages Jan 18, 2008 Xen hypervisor interface

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Jan Beulich

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#0 lore raw

PATCH 1/1 linux: prevent non-Xen modules from loading in Xen kernel

.. and vice versa.

Inspired by Zach Amsden's functionally similar VMI patch.

As usual, written and tested on 2.6.24-rc7 and made apply to the 2.6.18 tree without further testing.

Signed-off-by Jan Beulich <[email protected]>
drivers/xen/Kconfig +1 -1
Index: head-2008-01-08/drivers/xen/Kconfig
===================================================================
@@ -13,7 +13,7 @@ config XEN
 if XEN
 config XEN_INTERFACE_VERSION
 	hex
-	default 0x00030207
+	default 0x30207
 
 menu "XEN"
include/linux/vermagic.h +7 -1
Index: head-2008-01-08/include/linux/vermagic.h
===================================================================
@@ -17,6 +17,11 @@
 #else
 #define MODULE_VERMAGIC_MODULE_UNLOAD ""
 #endif
+#ifdef CONFIG_XEN
+#define MODULE_VERMAGIC_XEN "Xen:" __stringify(CONFIG_XEN_INTERFACE_VERSION) " "
+#else
+#define MODULE_VERMAGIC_XEN
+#endif
 #ifndef MODULE_ARCH_VERMAGIC
 #define MODULE_ARCH_VERMAGIC ""
 #endif

@@ -24,5 +29,6 @@
 #define VERMAGIC_STRING 						\
 	UTS_RELEASE " "							\
 	MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT 			\
-	MODULE_VERMAGIC_MODULE_UNLOAD MODULE_ARCH_VERMAGIC 		\
+	MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_XEN		\
+	MODULE_ARCH_VERMAGIC						\
 	"gcc-" __stringify(__GNUC__) "." __stringify(__GNUC_MINOR__)
#1 lore raw

Does the XEN_INTERFACE_VERSION add anything? It has not much to do with the module<->Linux-core interface. Seems a pretty random thing to stuff into the module magic version string.

-- Keir

Quoted 58 lines · Jan Beulich

.. and vice versa.

Inspired by Zach Amsden's functionally similar VMI patch.

As usual, written and tested on 2.6.24-rc7 and made apply to the 2.6.18 tree without further testing.

Signed-off-by Jan Beulich <[email protected]>

Index: head-2008-01-08/drivers/xen/Kconfig
===================================================================
--- head-2008-01-08.orig/drivers/xen/Kconfig 2008-01-08 12:26:03.000000000 +0100
+++ head-2008-01-08/drivers/xen/Kconfig 2008-01-08 14:56:58.000000000 +0100

drivers/xen/Kconfig +0 -0
@@ -13,7 +13,7 @@ config XEN
 if XEN
 config XEN_INTERFACE_VERSION

hex
- default 0x00030207
+ default 0x30207

menu "XEN"

Index: head-2008-01-08/include/linux/vermagic.h
===================================================================
--- head-2008-01-08.orig/include/linux/vermagic.h 2006-11-29 22:57:37.000000000 +0100
+++ head-2008-01-08/include/linux/vermagic.h 2008-01-08 15:01:52.000000000 +0100

include/linux/vermagic.h +2 -0
@@ -17,6 +17,11 @@
 #else
 #define MODULE_VERMAGIC_MODULE_UNLOAD ""
 #endif
+#ifdef CONFIG_XEN
+#define MODULE_VERMAGIC_XEN "Xen:" __stringify(CONFIG_XEN_INTERFACE_VERSION)

" "

include/linux/vermagic.h +5 -1
+#else
+#define MODULE_VERMAGIC_XEN
+#endif
 #ifndef MODULE_ARCH_VERMAGIC
 #define MODULE_ARCH_VERMAGIC ""
 #endif

@@ -24,5 +29,6 @@
 #define VERMAGIC_STRING       \
 UTS_RELEASE " "       \
 MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT    \
- MODULE_VERMAGIC_MODULE_UNLOAD MODULE_ARCH_VERMAGIC   \
+ MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_XEN  \
+ MODULE_ARCH_VERMAGIC      \
 "gcc-" __stringify(__GNUC__) "." __stringify(__GNUC_MINOR__)

_______________________________________________
Xen-devel mailing list
[email protected]
http://lists.xensource.com/xen-devel

author
#2 lore raw

Re: [PATCH] linux: prevent non-Xen modules fromloading in Xen kernel

It's intended to disallow cross-version loading of modules (i.e. a module compiled against a kernel built with a different [lower or higher] Xen interface) - allowing such can be as dangerous as loading a module that was compiled against native I believe.

Jan

Quoted 1 line
Quoted 1 line
Quoted 1 line

Keir Fraser <[email protected]> 18.01.08 16:35 >>>

Does the XEN_INTERFACE_VERSION add anything? It has not much to do with the module<->Linux-core interface. Seems a pretty random thing to stuff into the module magic version string.

-- Keir

Quoted 58 lines · Jan Beulich

.. and vice versa.

Inspired by Zach Amsden's functionally similar VMI patch.

As usual, written and tested on 2.6.24-rc7 and made apply to the 2.6.18 tree without further testing.

Signed-off-by Jan Beulich <[email protected]>

Index: head-2008-01-08/drivers/xen/Kconfig
===================================================================
--- head-2008-01-08.orig/drivers/xen/Kconfig 2008-01-08 12:26:03.000000000 +0100
+++ head-2008-01-08/drivers/xen/Kconfig 2008-01-08 14:56:58.000000000 +0100

drivers/xen/Kconfig +0 -0
@@ -13,7 +13,7 @@ config XEN
 if XEN
 config XEN_INTERFACE_VERSION

hex
- default 0x00030207
+ default 0x30207

menu "XEN"

Index: head-2008-01-08/include/linux/vermagic.h
===================================================================
--- head-2008-01-08.orig/include/linux/vermagic.h 2006-11-29 22:57:37.000000000 +0100
+++ head-2008-01-08/include/linux/vermagic.h 2008-01-08 15:01:52.000000000 +0100

include/linux/vermagic.h +2 -0
@@ -17,6 +17,11 @@
 #else
 #define MODULE_VERMAGIC_MODULE_UNLOAD ""
 #endif
+#ifdef CONFIG_XEN
+#define MODULE_VERMAGIC_XEN "Xen:" __stringify(CONFIG_XEN_INTERFACE_VERSION)

" "

include/linux/vermagic.h +5 -1
+#else
+#define MODULE_VERMAGIC_XEN
+#endif
 #ifndef MODULE_ARCH_VERMAGIC
 #define MODULE_ARCH_VERMAGIC ""
 #endif

@@ -24,5 +29,6 @@
 #define VERMAGIC_STRING       \
 UTS_RELEASE " "       \
 MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT    \
- MODULE_VERMAGIC_MODULE_UNLOAD MODULE_ARCH_VERMAGIC   \
+ MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_XEN  \
+ MODULE_ARCH_VERMAGIC      \
 "gcc-" __stringify(__GNUC__) "." __stringify(__GNUC_MINOR__)

_______________________________________________
Xen-devel mailing list
[email protected]
http://lists.xensource.com/xen-devel

#3 lore raw

Re: [PATCH] linux: prevent non-Xen modules fromloading in Xen kernel

I disagree. The xen interface version number is simply to allow downgrading of the API exposed by the Xen public headers. And it *is* specifically the source API; *not* the ABI. Xen's ABIs are always backward compatible (old guest driver; new Xen will always work), and for forward compatibility (new guest driver; old Xen) we expect the guest driver to gracefully degrade its functionality.

This is orthogonal to what you are trying to achieve. So, can we just add "Xen " to the magic string?

-- Keir

Quoted 77 lines · Jan Beulich

It's intended to disallow cross-version loading of modules (i.e. a module compiled against a kernel built with a different [lower or higher] Xen interface) - allowing such can be as dangerous as loading a module that was compiled against native I believe.

Jan

Quoted 1 line
Quoted 1 line
Quoted 1 line

Keir Fraser <[email protected]> 18.01.08 16:35 >>>

Does the XEN_INTERFACE_VERSION add anything? It has not much to do with the module<->Linux-core interface. Seems a pretty random thing to stuff into the module magic version string.

-- Keir

Quoted 58 lines · Jan Beulich

.. and vice versa.

Inspired by Zach Amsden's functionally similar VMI patch.

As usual, written and tested on 2.6.24-rc7 and made apply to the 2.6.18 tree without further testing.

Signed-off-by Jan Beulich <[email protected]>

Index: head-2008-01-08/drivers/xen/Kconfig
===================================================================
--- head-2008-01-08.orig/drivers/xen/Kconfig 2008-01-08 12:26:03.000000000 +0100
+++ head-2008-01-08/drivers/xen/Kconfig 2008-01-08 14:56:58.000000000 +0100

drivers/xen/Kconfig +0 -0
@@ -13,7 +13,7 @@ config XEN
 if XEN
 config XEN_INTERFACE_VERSION

hex
- default 0x00030207
+ default 0x30207

menu "XEN"

Index: head-2008-01-08/include/linux/vermagic.h
===================================================================
--- head-2008-01-08.orig/include/linux/vermagic.h 2006-11-29 22:57:37.000000000 +0100
+++ head-2008-01-08/include/linux/vermagic.h 2008-01-08 15:01:52.000000000 +0100

include/linux/vermagic.h +2 -0
@@ -17,6 +17,11 @@
 #else
 #define MODULE_VERMAGIC_MODULE_UNLOAD ""
 #endif
+#ifdef CONFIG_XEN
+#define MODULE_VERMAGIC_XEN "Xen:" __stringify(CONFIG_XEN_INTERFACE_VERSION)

" "

include/linux/vermagic.h +5 -1
+#else
+#define MODULE_VERMAGIC_XEN
+#endif
 #ifndef MODULE_ARCH_VERMAGIC
 #define MODULE_ARCH_VERMAGIC ""
 #endif

@@ -24,5 +29,6 @@
 #define VERMAGIC_STRING       \
 UTS_RELEASE " "       \
 MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT    \
- MODULE_VERMAGIC_MODULE_UNLOAD MODULE_ARCH_VERMAGIC   \
+ MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_XEN  \
+ MODULE_ARCH_VERMAGIC      \
 "gcc-" __stringify(__GNUC__) "." __stringify(__GNUC_MINOR__)

_______________________________________________
Xen-devel mailing list
[email protected]
http://lists.xensource.com/xen-devel

author
#4 lore raw

Re: [PATCH] linux: prevent non-Xen modulesfromloading in Xen kernel

Quoted 7 lines
Quoted 1 line
Quoted 1 line

Keir Fraser <[email protected]> 18.01.08 17:07 >>>

I disagree. The xen interface version number is simply to allow downgrading of the API exposed by the Xen public headers. And it *is* specifically the source API; *not* the ABI. Xen's ABIs are always backward compatible (old guest driver; new Xen will always work), and for forward compatibility (new guest driver; old Xen) we expect the guest driver to gracefully degrade its functionality.

Yeah, it really wasn't meant to cover that (which I know has been stable enough during a reasonably long time now), but rather to have a little less coarse separation than with just "Xen ", but

Quoted 2 lines

This is orthogonal to what you are trying to achieve. So, can we just add "Xen " to the magic string?

... sure we can.

Jan