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From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@kernel.org>,
	Balbir Singh <bsingharora@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H . J . Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Weijiang Yang <weijiang.yang@intel.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	John Allen <john.allen@amd.com>,
	kcc@google.com, eranian@google.com, rppt@kernel.org,
	jamorris@linux.microsoft.com, dethoma@microsoft.com,
	akpm@linux-foundation.org, Andrew.Cooper3@citrix.com,
	christina.schimpe@intel.com
Cc: rick.p.edgecombe@intel.com
Subject: [PATCH v5 39/39] x86/shstk: Add ARCH_SHSTK_STATUS
Date: Thu, 19 Jan 2023 13:23:17 -0800	[thread overview]
Message-ID: <20230119212317.8324-40-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20230119212317.8324-1-rick.p.edgecombe@intel.com>

CRIU and GDB need to get the current shadow stack and WRSS enablement
status. This information is already available via /proc/pid/status, but
this is inconvenient for CRIU because it involves parsing the text output
in an area of the code where this is difficult. Provide a status
arch_prctl(), ARCH_SHSTK_STATUS for retrieving the status. Have arg2 be a
userspace address, and make the new arch_prctl simply copy the features
out to userspace.

Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---

v5:
 - Fix typo in commit log

v4:
 - New patch

 Documentation/x86/shstk.rst       | 6 ++++++
 arch/x86/include/asm/shstk.h      | 4 ++--
 arch/x86/include/uapi/asm/prctl.h | 1 +
 arch/x86/kernel/process_64.c      | 1 +
 arch/x86/kernel/shstk.c           | 8 +++++++-
 5 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/Documentation/x86/shstk.rst b/Documentation/x86/shstk.rst
index e8ed5fc0f7ae..7f4af798794e 100644
--- a/Documentation/x86/shstk.rst
+++ b/Documentation/x86/shstk.rst
@@ -77,6 +77,11 @@ arch_prctl(ARCH_SHSTK_UNLOCK, unsigned long features)
     Unlock features. 'features' is a mask of all features to unlock. All
     bits set are processed, unset bits are ignored. Only works via ptrace.
 
+arch_prctl(ARCH_SHSTK_STATUS, unsigned long addr)
+    Copy the currently enabled features to the address passed in addr. The
+    features are described using the bits passed into the others in
+    'features'.
+
 The return values are as follows. On success, return 0. On error, errno can
 be::
 
@@ -84,6 +89,7 @@ be::
         -ENOTSUPP if the feature is not supported by the hardware or
          kernel.
         -EINVAL arguments (non existing feature, etc)
+        -EFAULT if could not copy information back to userspace
 
 The feature's bits supported are::
 
diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h
index 746c040f7cb6..73de995f55ca 100644
--- a/arch/x86/include/asm/shstk.h
+++ b/arch/x86/include/asm/shstk.h
@@ -14,7 +14,7 @@ struct thread_shstk {
 	u64	size;
 };
 
-long shstk_prctl(struct task_struct *task, int option, unsigned long features);
+long shstk_prctl(struct task_struct *task, int option, unsigned long arg2);
 void reset_thread_features(void);
 int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags,
 			     unsigned long stack_size,
@@ -24,7 +24,7 @@ int setup_signal_shadow_stack(struct ksignal *ksig);
 int restore_signal_shadow_stack(void);
 #else
 static inline long shstk_prctl(struct task_struct *task, int option,
-			     unsigned long features) { return -EINVAL; }
+			     unsigned long arg2) { return -EINVAL; }
 static inline void reset_thread_features(void) {}
 static inline int shstk_alloc_thread_stack(struct task_struct *p,
 					   unsigned long clone_flags,
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 200efbbe5809..1b85bc876c2d 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -26,6 +26,7 @@
 #define ARCH_SHSTK_DISABLE		0x5002
 #define ARCH_SHSTK_LOCK			0x5003
 #define ARCH_SHSTK_UNLOCK		0x5004
+#define ARCH_SHSTK_STATUS		0x5005
 
 /* ARCH_SHSTK_ features bits */
 #define ARCH_SHSTK_SHSTK		(1ULL <<  0)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d368854fa9c4..dde43caf196e 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -836,6 +836,7 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
 	case ARCH_SHSTK_DISABLE:
 	case ARCH_SHSTK_LOCK:
 	case ARCH_SHSTK_UNLOCK:
+	case ARCH_SHSTK_STATUS:
 		return shstk_prctl(task, option, arg2);
 	default:
 		ret = -EINVAL;
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index a639119a21c5..3b1433bd63c7 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -445,8 +445,14 @@ SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsi
 	return alloc_shstk(addr, aligned_size, size, set_tok);
 }
 
-long shstk_prctl(struct task_struct *task, int option, unsigned long features)
+long shstk_prctl(struct task_struct *task, int option, unsigned long arg2)
 {
+	unsigned long features = arg2;
+
+	if (option == ARCH_SHSTK_STATUS) {
+		return put_user(task->thread.features, (unsigned long __user *)arg2);
+	}
+
 	if (option == ARCH_SHSTK_LOCK) {
 		task->thread.features_locked |= features;
 		return 0;
-- 
2.17.1



  parent reply	other threads:[~2023-01-19 21:24 UTC|newest]

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-19 21:22 [PATCH v5 00/39] Shadow stacks for userspace Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 01/39] Documentation/x86: Add CET shadow stack description Rick Edgecombe
2023-01-20  0:38   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 02/39] x86/shstk: Add Kconfig option for shadow stack Rick Edgecombe
2023-01-20  0:40   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 03/39] x86/cpufeatures: Add CPU feature flags for shadow stacks Rick Edgecombe
2023-01-20  0:44   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 04/39] x86/cpufeatures: Enable CET CR4 bit for shadow stack Rick Edgecombe
2023-01-20  0:46   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 05/39] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Rick Edgecombe
2023-01-20  0:46   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 06/39] x86/fpu: Add helper for modifying xstate Rick Edgecombe
2023-01-20  0:47   ` Kees Cook
2023-02-01 11:01   ` Borislav Petkov
2023-02-01 17:31     ` Edgecombe, Rick P
2023-02-01 18:18       ` Borislav Petkov
2023-01-19 21:22 ` [PATCH v5 07/39] x86: Add user control-protection fault handler Rick Edgecombe
2023-01-20  0:50   ` Kees Cook
2023-02-03 19:09   ` Borislav Petkov
2023-02-03 19:24     ` Edgecombe, Rick P
2023-02-03 19:44       ` Borislav Petkov
2023-02-03 23:01         ` Edgecombe, Rick P
2023-02-04 10:37           ` Borislav Petkov
2023-01-19 21:22 ` [PATCH v5 08/39] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Rick Edgecombe
2023-01-20  0:52   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 09/39] x86/mm: Move pmd_write(), pud_write() up in the file Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 10/39] x86/mm: Introduce _PAGE_COW Rick Edgecombe
2023-01-20  0:55   ` Kees Cook
2023-01-23  9:16   ` David Hildenbrand
2023-01-23  9:28   ` David Hildenbrand
2023-01-23 20:56     ` Edgecombe, Rick P
2023-01-24 16:28       ` David Hildenbrand
2023-01-19 21:22 ` [PATCH v5 11/39] x86/mm: Update pte_modify for _PAGE_COW Rick Edgecombe
2023-01-20  0:57   ` Kees Cook
2023-02-09 14:08   ` Borislav Petkov
2023-02-09 17:09     ` Edgecombe, Rick P
2023-02-10 13:57       ` Borislav Petkov
2023-02-10 17:00         ` Edgecombe, Rick P
2023-02-17 16:11           ` Borislav Petkov
2023-02-17 16:53             ` Edgecombe, Rick P
2023-01-19 21:22 ` [PATCH v5 12/39] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Rick Edgecombe
2023-01-20  0:58   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 13/39] x86/mm: Start actually marking _PAGE_COW Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 14/39] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 15/39] mm: Introduce VM_SHADOW_STACK for shadow stack memory Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 16/39] x86/mm: Check shadow stack page fault errors Rick Edgecombe
2023-01-20  0:59   ` Kees Cook
2023-01-19 21:22 ` [PATCH v5 17/39] x86/mm: Update maybe_mkwrite() for shadow stack Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 18/39] mm: Handle faultless write upgrades for shstk Rick Edgecombe
2023-01-23  9:50   ` David Hildenbrand
2023-01-23 20:47     ` Edgecombe, Rick P
2023-01-24 16:24       ` David Hildenbrand
2023-01-24 18:14         ` Edgecombe, Rick P
2023-01-25  9:27           ` David Hildenbrand
2023-01-25 18:43             ` Edgecombe, Rick P
2023-01-26  0:59               ` Edgecombe, Rick P
2023-01-26  8:46                 ` David Hildenbrand
2023-01-26 20:19                   ` Edgecombe, Rick P
2023-01-27 16:12                     ` David Hildenbrand
2023-01-28  0:51                       ` Edgecombe, Rick P
2023-01-31  8:46                         ` David Hildenbrand
2023-01-31 23:33                           ` Edgecombe, Rick P
2023-02-01  9:03                             ` David Hildenbrand
2023-02-01 17:32                               ` Edgecombe, Rick P
2023-02-01 18:03                                 ` David Hildenbrand
2023-01-26  8:57               ` David Hildenbrand
2023-01-26 20:16                 ` Edgecombe, Rick P
2023-01-27 16:19                   ` David Hildenbrand
2023-01-19 21:22 ` [PATCH v5 19/39] mm: Fixup places that call pte_mkwrite() directly Rick Edgecombe
2023-01-20  1:01   ` Kees Cook
2023-02-14  0:09   ` Deepak Gupta
2023-02-14  1:07     ` Edgecombe, Rick P
2023-02-14  6:10       ` Deepak Gupta
2023-02-14 18:24         ` Edgecombe, Rick P
2023-02-15  6:37           ` Deepak Gupta
2023-01-19 21:22 ` [PATCH v5 20/39] mm: Add guard pages around a shadow stack Rick Edgecombe
2023-01-19 21:22 ` [PATCH v5 21/39] mm/mmap: Add shadow stack pages to memory accounting Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 22/39] mm: Re-introduce vm_flags to do_mmap() Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 23/39] mm: Don't allow write GUPs to shadow stack memory Rick Edgecombe
2023-01-23  9:10   ` David Hildenbrand
2023-01-23 10:45     ` Florian Weimer
2023-01-23 20:46       ` Edgecombe, Rick P
2023-01-24 16:26         ` David Hildenbrand
2023-01-24 18:42           ` Edgecombe, Rick P
2023-01-24 23:08             ` Kees Cook
2023-01-24 23:41               ` Edgecombe, Rick P
2023-01-25  9:29                 ` David Hildenbrand
2023-01-25 15:23                   ` Kees Cook
2023-01-25 15:36             ` Schimpe, Christina
2023-01-25 16:43               ` Schimpe, Christina
2023-01-19 21:23 ` [PATCH v5 24/39] x86/mm: Introduce MAP_ABOVE4G Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 25/39] mm: Warn on shadow stack memory in wrong vma Rick Edgecombe
2023-01-20  1:01   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 26/39] x86: Introduce userspace API for shadow stack Rick Edgecombe
2023-01-20  1:04   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 27/39] x86/shstk: Add user-mode shadow stack support Rick Edgecombe
2023-01-20  1:05   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 28/39] x86/shstk: Handle thread shadow stack Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 29/39] x86/shstk: Introduce routines modifying shstk Rick Edgecombe
2023-01-20  1:05   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 30/39] x86/shstk: Handle signals for shadow stack Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 31/39] x86/shstk: Introduce map_shadow_stack syscall Rick Edgecombe
2023-01-20  1:07   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 32/39] x86/shstk: Support WRSS for userspace Rick Edgecombe
2023-01-20  1:06   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 33/39] x86: Expose thread features in /proc/$PID/status Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 34/39] x86/shstk: Wire in shadow stack interface Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 35/39] selftests/x86: Add shadow stack test Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 36/39] x86/fpu: Add helper for initing features Rick Edgecombe
2023-01-19 21:23 ` [PATCH v5 37/39] x86: Add PTRACE interface for shadow stack Rick Edgecombe
2023-01-20  1:08   ` Kees Cook
2023-01-19 21:23 ` [PATCH v5 38/39] x86/shstk: Add ARCH_SHSTK_UNLOCK Rick Edgecombe
2023-01-19 21:23 ` Rick Edgecombe [this message]
2023-01-20  1:08   ` [PATCH v5 39/39] x86/shstk: Add ARCH_SHSTK_STATUS Kees Cook
2023-01-19 22:26 ` [PATCH v5 00/39] Shadow stacks for userspace Andrew Morton
2023-01-20 17:27   ` Edgecombe, Rick P
2023-01-20 19:19     ` Kees Cook
2023-01-25 19:46       ` Edgecombe, Rick P
2023-01-20 17:48 ` John Allen
2023-01-22  8:20 ` Mike Rapoport

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