diff mbox series

[v8,1/7] mseal sysmap: kernel config and header change

Message ID 20250303050921.3033083-2-jeffxu@google.com (mailing list archive)
State New
Headers show
Series mseal system mappings | expand

Commit Message

Jeff Xu March 3, 2025, 5:09 a.m. UTC 
From: Jeff Xu <jeffxu@chromium.org>

Provide infrastructure to mseal system mappings. Establish
two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS,
ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP
macro for future patches.

Signed-off-by: Jeff Xu <jeffxu@chromium.org>
---
 include/linux/mm.h | 10 ++++++++++
 init/Kconfig       | 22 ++++++++++++++++++++++
 security/Kconfig   | 21 +++++++++++++++++++++
 3 files changed, 53 insertions(+)

Comments

Lorenzo Stoakes March 3, 2025, 11:51 a.m. UTC | #1 
On Mon, Mar 03, 2025 at 05:09:15AM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@chromium.org>
>
> Provide infrastructure to mseal system mappings. Establish
> two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS,
> ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP
> macro for future patches.
>
> Signed-off-by: Jeff Xu <jeffxu@chromium.org>

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
>  include/linux/mm.h | 10 ++++++++++
>  init/Kconfig       | 22 ++++++++++++++++++++++
>  security/Kconfig   | 21 +++++++++++++++++++++
>  3 files changed, 53 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7b1068ddcbb7..8b800941678d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4155,4 +4155,14 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st
>  int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status);
>  int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
>
> +
> +/*
> + * mseal of userspace process's system mappings.
> + */
> +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
> +#define VM_SEALED_SYSMAP	VM_SEALED
> +#else
> +#define VM_SEALED_SYSMAP	VM_NONE
> +#endif
> +

Thanks.

>  #endif /* _LINUX_MM_H */
> diff --git a/init/Kconfig b/init/Kconfig
> index d0d021b3fa3b..c90dd8778993 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1882,6 +1882,28 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS
>  config ARCH_HAS_MEMBARRIER_SYNC_CORE
>  	bool
>
> +config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	bool
> +	help
> +	  Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  To enable this feature, the architecture needs to update their
> +	  special mappings calls to include the sealing flag and confirm
> +	  that it doesn't unmap/remap system mappings during the life
> +	  time of the process. The existence of this flag for an architecture
> +	  implies that it does not require the remapping of thest system
> +	  mappings during process lifetime, so sealing these mappings is safe
> +	  from a kernel perspective.

Great, perfect thanks!

> +
> +	  After the architecture enables this, a distribution can set
> +	  CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config HAVE_PERF_EVENTS
>  	bool
>  	help
> diff --git a/security/Kconfig b/security/Kconfig
> index f10dbf15c294..5311f4a6786c 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -51,6 +51,27 @@ config PROC_MEM_NO_FORCE
>
>  endchoice
>
> +config MSEAL_SYSTEM_MAPPINGS
> +	bool "mseal system mappings"
> +	depends on 64BIT
> +	depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	depends on !CHECKPOINT_RESTORE
> +	help
> +	  Apply mseal on system mappings.
> +	  The system mappings includes vdso, vvar, vvar_vclock,
> +	  vectors (arm compact-mode), sigpage (arm compact-mode), uprobes.
> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  WARNING: This feature breaks programs which rely on relocating
> +	  or unmapping system mappings. Known broken software at the time
> +	  of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore
> +	  this config can't be enabled universally.

Perfect thanks!

> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config SECURITY
>  	bool "Enable different security models"
>  	depends on SYSFS
> --
> 2.48.1.711.g2feabab25a-goog
>
Liam R. Howlett March 3, 2025, 3:02 p.m. UTC | #2 
* jeffxu@chromium.org <jeffxu@chromium.org> [250303 00:09]:
> From: Jeff Xu <jeffxu@chromium.org>
> 
> Provide infrastructure to mseal system mappings. Establish
> two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS,
> ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP
> macro for future patches.
> 
> Signed-off-by: Jeff Xu <jeffxu@chromium.org>

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>


> ---
>  include/linux/mm.h | 10 ++++++++++
>  init/Kconfig       | 22 ++++++++++++++++++++++
>  security/Kconfig   | 21 +++++++++++++++++++++
>  3 files changed, 53 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7b1068ddcbb7..8b800941678d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4155,4 +4155,14 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st
>  int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status);
>  int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
>  
> +
> +/*
> + * mseal of userspace process's system mappings.
> + */
> +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
> +#define VM_SEALED_SYSMAP	VM_SEALED
> +#else
> +#define VM_SEALED_SYSMAP	VM_NONE
> +#endif
> +
>  #endif /* _LINUX_MM_H */
> diff --git a/init/Kconfig b/init/Kconfig
> index d0d021b3fa3b..c90dd8778993 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1882,6 +1882,28 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS
>  config ARCH_HAS_MEMBARRIER_SYNC_CORE
>  	bool
>  
> +config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	bool
> +	help
> +	  Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  To enable this feature, the architecture needs to update their
> +	  special mappings calls to include the sealing flag and confirm
> +	  that it doesn't unmap/remap system mappings during the life
> +	  time of the process. The existence of this flag for an architecture
> +	  implies that it does not require the remapping of thest system
> +	  mappings during process lifetime, so sealing these mappings is safe
> +	  from a kernel perspective.
> +
> +	  After the architecture enables this, a distribution can set
> +	  CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config HAVE_PERF_EVENTS
>  	bool
>  	help
> diff --git a/security/Kconfig b/security/Kconfig
> index f10dbf15c294..5311f4a6786c 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -51,6 +51,27 @@ config PROC_MEM_NO_FORCE
>  
>  endchoice
>  
> +config MSEAL_SYSTEM_MAPPINGS
> +	bool "mseal system mappings"
> +	depends on 64BIT
> +	depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	depends on !CHECKPOINT_RESTORE
> +	help
> +	  Apply mseal on system mappings.
> +	  The system mappings includes vdso, vvar, vvar_vclock,
> +	  vectors (arm compact-mode), sigpage (arm compact-mode), uprobes.
> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  WARNING: This feature breaks programs which rely on relocating
> +	  or unmapping system mappings. Known broken software at the time
> +	  of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore
> +	  this config can't be enabled universally.
> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config SECURITY
>  	bool "Enable different security models"
>  	depends on SYSFS
> -- 
> 2.48.1.711.g2feabab25a-goog
>
Kees Cook March 3, 2025, 4:37 p.m. UTC | #3 
On Mon, Mar 03, 2025 at 05:09:15AM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@chromium.org>
> 
> Provide infrastructure to mseal system mappings. Establish
> two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS,
> ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP
> macro for future patches.
> 
> Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> ---
>  include/linux/mm.h | 10 ++++++++++
>  init/Kconfig       | 22 ++++++++++++++++++++++
>  security/Kconfig   | 21 +++++++++++++++++++++
>  3 files changed, 53 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7b1068ddcbb7..8b800941678d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4155,4 +4155,14 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st
>  int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status);
>  int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
>  
> +
> +/*
> + * mseal of userspace process's system mappings.
> + */
> +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
> +#define VM_SEALED_SYSMAP	VM_SEALED
> +#else
> +#define VM_SEALED_SYSMAP	VM_NONE
> +#endif
> +
>  #endif /* _LINUX_MM_H */
> diff --git a/init/Kconfig b/init/Kconfig
> index d0d021b3fa3b..c90dd8778993 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1882,6 +1882,28 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS
>  config ARCH_HAS_MEMBARRIER_SYNC_CORE
>  	bool
>  
> +config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	bool
> +	help
> +	  Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  To enable this feature, the architecture needs to update their
> +	  special mappings calls to include the sealing flag and confirm
> +	  that it doesn't unmap/remap system mappings during the life
> +	  time of the process. The existence of this flag for an architecture
> +	  implies that it does not require the remapping of thest system

typo nit: "the" instead of "thest"

> +	  mappings during process lifetime, so sealing these mappings is safe
> +	  from a kernel perspective.
> +
> +	  After the architecture enables this, a distribution can set
> +	  CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config HAVE_PERF_EVENTS
>  	bool
>  	help
> diff --git a/security/Kconfig b/security/Kconfig
> index f10dbf15c294..5311f4a6786c 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -51,6 +51,27 @@ config PROC_MEM_NO_FORCE
>  
>  endchoice
>  
> +config MSEAL_SYSTEM_MAPPINGS
> +	bool "mseal system mappings"
> +	depends on 64BIT
> +	depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> +	depends on !CHECKPOINT_RESTORE
> +	help
> +	  Apply mseal on system mappings.
> +	  The system mappings includes vdso, vvar, vvar_vclock,
> +	  vectors (arm compact-mode), sigpage (arm compact-mode), uprobes.

typo nits: "compat" instead of "compact".

> +
> +	  A 64-bit kernel is required for the memory sealing feature.
> +	  No specific hardware features from the CPU are needed.
> +
> +	  WARNING: This feature breaks programs which rely on relocating
> +	  or unmapping system mappings. Known broken software at the time
> +	  of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore
> +	  this config can't be enabled universally.
> +
> +	  For complete descriptions of memory sealing, please see
> +	  Documentation/userspace-api/mseal.rst
> +
>  config SECURITY
>  	bool "Enable different security models"
>  	depends on SYSFS
> -- 
> 2.48.1.711.g2feabab25a-goog
> 

Perhaps akpm can fix these up directly instead of a v9 spin?

But otherwise, yes, reads well to me:

Reviewed-by: Kees Cook <kees@kernel.org>
Jeff Xu March 3, 2025, 7:29 p.m. UTC | #4 
On Mon, Mar 3, 2025 at 8:37 AM Kees Cook <kees@kernel.org> wrote:
>
> On Mon, Mar 03, 2025 at 05:09:15AM +0000, jeffxu@chromium.org wrote:
> > From: Jeff Xu <jeffxu@chromium.org>
> >
> > Provide infrastructure to mseal system mappings. Establish
> > two kernel configs (CONFIG_MSEAL_SYSTEM_MAPPINGS,
> > ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS) and VM_SEALED_SYSMAP
> > macro for future patches.
> >
> > Signed-off-by: Jeff Xu <jeffxu@chromium.org>
> > ---
> >  include/linux/mm.h | 10 ++++++++++
> >  init/Kconfig       | 22 ++++++++++++++++++++++
> >  security/Kconfig   | 21 +++++++++++++++++++++
> >  3 files changed, 53 insertions(+)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 7b1068ddcbb7..8b800941678d 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -4155,4 +4155,14 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st
> >  int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status);
> >  int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
> >
> > +
> > +/*
> > + * mseal of userspace process's system mappings.
> > + */
> > +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
> > +#define VM_SEALED_SYSMAP     VM_SEALED
> > +#else
> > +#define VM_SEALED_SYSMAP     VM_NONE
> > +#endif
> > +
> >  #endif /* _LINUX_MM_H */
> > diff --git a/init/Kconfig b/init/Kconfig
> > index d0d021b3fa3b..c90dd8778993 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1882,6 +1882,28 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS
> >  config ARCH_HAS_MEMBARRIER_SYNC_CORE
> >       bool
> >
> > +config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> > +     bool
> > +     help
> > +       Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
> > +
> > +       A 64-bit kernel is required for the memory sealing feature.
> > +       No specific hardware features from the CPU are needed.
> > +
> > +       To enable this feature, the architecture needs to update their
> > +       special mappings calls to include the sealing flag and confirm
> > +       that it doesn't unmap/remap system mappings during the life
> > +       time of the process. The existence of this flag for an architecture
> > +       implies that it does not require the remapping of thest system
>
> typo nit: "the" instead of "thest"
>
> > +       mappings during process lifetime, so sealing these mappings is safe
> > +       from a kernel perspective.
> > +
> > +       After the architecture enables this, a distribution can set
> > +       CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
> > +
> > +       For complete descriptions of memory sealing, please see
> > +       Documentation/userspace-api/mseal.rst
> > +
> >  config HAVE_PERF_EVENTS
> >       bool
> >       help
> > diff --git a/security/Kconfig b/security/Kconfig
> > index f10dbf15c294..5311f4a6786c 100644
> > --- a/security/Kconfig
> > +++ b/security/Kconfig
> > @@ -51,6 +51,27 @@ config PROC_MEM_NO_FORCE
> >
> >  endchoice
> >
> > +config MSEAL_SYSTEM_MAPPINGS
> > +     bool "mseal system mappings"
> > +     depends on 64BIT
> > +     depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
> > +     depends on !CHECKPOINT_RESTORE
> > +     help
> > +       Apply mseal on system mappings.
> > +       The system mappings includes vdso, vvar, vvar_vclock,
> > +       vectors (arm compact-mode), sigpage (arm compact-mode), uprobes.
>
> typo nits: "compat" instead of "compact".
>
Got it, I will change everywhere for this (mseal.rst, coverletter)


> > +
> > +       A 64-bit kernel is required for the memory sealing feature.
> > +       No specific hardware features from the CPU are needed.
> > +
> > +       WARNING: This feature breaks programs which rely on relocating
> > +       or unmapping system mappings. Known broken software at the time
> > +       of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore
> > +       this config can't be enabled universally.
> > +
> > +       For complete descriptions of memory sealing, please see
> > +       Documentation/userspace-api/mseal.rst
> > +
> >  config SECURITY
> >       bool "Enable different security models"
> >       depends on SYSFS
> > --
> > 2.48.1.711.g2feabab25a-goog
> >
>
> Perhaps akpm can fix these up directly instead of a v9 spin?
>
V9 is relatively easy for me. I probably need a good version for
backporting to chromeOS/Android.

If all goes well, I'll follow up with a V10 based on Thomas
Weißschuh's vdso refactor branch [1] [2].

[1] https://lore.kernel.org/all/CABi2SkXwaJ=s3XqHKu1aFVfcacgxpQ5Ji1_BqaN+ch2i_RnA9Q@mail.gmail.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=timers/vdso


> But otherwise, yes, reads well to me:
>
> Reviewed-by: Kees Cook <kees@kernel.org>
>
> --
> Kees Cook
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7b1068ddcbb7..8b800941678d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4155,4 +4155,14 @@  int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st
 int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status);
 int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status);
 
+
+/*
+ * mseal of userspace process's system mappings.
+ */
+#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS
+#define VM_SEALED_SYSMAP	VM_SEALED
+#else
+#define VM_SEALED_SYSMAP	VM_NONE
+#endif
+
 #endif /* _LINUX_MM_H */
diff --git a/init/Kconfig b/init/Kconfig
index d0d021b3fa3b..c90dd8778993 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1882,6 +1882,28 @@  config ARCH_HAS_MEMBARRIER_CALLBACKS
 config ARCH_HAS_MEMBARRIER_SYNC_CORE
 	bool
 
+config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
+	bool
+	help
+	  Control MSEAL_SYSTEM_MAPPINGS access based on architecture.
+
+	  A 64-bit kernel is required for the memory sealing feature.
+	  No specific hardware features from the CPU are needed.
+
+	  To enable this feature, the architecture needs to update their
+	  special mappings calls to include the sealing flag and confirm
+	  that it doesn't unmap/remap system mappings during the life
+	  time of the process. The existence of this flag for an architecture
+	  implies that it does not require the remapping of thest system
+	  mappings during process lifetime, so sealing these mappings is safe
+	  from a kernel perspective.
+
+	  After the architecture enables this, a distribution can set
+	  CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature.
+
+	  For complete descriptions of memory sealing, please see
+	  Documentation/userspace-api/mseal.rst
+
 config HAVE_PERF_EVENTS
 	bool
 	help
diff --git a/security/Kconfig b/security/Kconfig
index f10dbf15c294..5311f4a6786c 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -51,6 +51,27 @@  config PROC_MEM_NO_FORCE
 
 endchoice
 
+config MSEAL_SYSTEM_MAPPINGS
+	bool "mseal system mappings"
+	depends on 64BIT
+	depends on ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
+	depends on !CHECKPOINT_RESTORE
+	help
+	  Apply mseal on system mappings.
+	  The system mappings includes vdso, vvar, vvar_vclock,
+	  vectors (arm compact-mode), sigpage (arm compact-mode), uprobes.
+
+	  A 64-bit kernel is required for the memory sealing feature.
+	  No specific hardware features from the CPU are needed.
+
+	  WARNING: This feature breaks programs which rely on relocating
+	  or unmapping system mappings. Known broken software at the time
+	  of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore
+	  this config can't be enabled universally.
+
+	  For complete descriptions of memory sealing, please see
+	  Documentation/userspace-api/mseal.rst
+
 config SECURITY
 	bool "Enable different security models"
 	depends on SYSFS