From: jeffxu@chromium.org
To: dave.hansen@intel.com, luto@kernel.org, jorgelo@chromium.org,
keescook@chromium.org, groeck@chromium.org, jannh@google.com,
sroettger@google.com
Cc: akpm@linux-foundation.org, jeffxu@google.com,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: [PATCH 2/6] PKEY: Add arch_check_pkey_enforce_api()
Date: Mon, 15 May 2023 13:05:48 +0000 [thread overview]
Message-ID: <20230515130553.2311248-3-jeffxu@chromium.org> (raw)
In-Reply-To: <20230515130553.2311248-1-jeffxu@chromium.org>
From: Jeff Xu <jeffxu@google.com>
This patch adds an architecture-independent function,
arch_check_pkey_enforce_api(), that checks whether the calling thread
has write access to the PKRU for a given range of memory. If the
memory range is protected by PKEY_ENFORCE_API, then the thread must
have write access to the PKRU in order to make changes to the memory
mapping (such as mprotect/munmap).
This function is used by the kernel to enforce the
PKEY_ENFORCE_API flag.
Signed-off-by: Jeff Xu<jeffxu@google.com>
---
arch/powerpc/include/asm/pkeys.h | 8 +++++
arch/x86/include/asm/pkeys.h | 50 ++++++++++++++++++++++++++++++++
include/linux/pkeys.h | 9 ++++++
3 files changed, 67 insertions(+)
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 943333ac0fee..24c481e5e95b 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -177,5 +177,13 @@ static inline bool arch_check_pkey_alloc_flags(unsigned long flags)
return true;
}
+static inline int arch_check_pkey_enforce_api(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ /* Allow by default */
+ return 0;
+}
+
extern void pkey_mm_init(struct mm_struct *mm);
#endif /*_ASM_POWERPC_KEYS_H */
diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index ecadf04a8251..8b94ffc4ca32 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -161,4 +161,54 @@ static inline bool arch_check_pkey_alloc_flags(unsigned long flags)
return true;
}
+
+static inline int __arch_check_vma_pkey_for_write(struct vm_area_struct *vma)
+{
+ int pkey = vma_pkey(vma);
+
+ if (mm_pkey_enforce_api(vma->vm_mm, pkey)) {
+ if (!__pkru_allows_write(read_pkru(), pkey))
+ return -EACCES;
+ }
+
+ return 0;
+}
+
+/*
+ * arch_check_pkey_enforce_api is used by the kernel to enforce
+ * PKEY_ENFORCE_API flag.
+ * It checks whether the calling thread has write access to the PKRU
+ * for a given range of memory. If the memory range is protected by
+ * PKEY_ENFORCE_API, then the thread must have write access to the
+ * PKRU in order to make changes to the memory mapping, such as
+ * mprotect/munmap.
+ */
+static inline int arch_check_pkey_enforce_api(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ int error;
+ struct vm_area_struct *vma;
+
+ if (!arch_pkeys_enabled())
+ return 0;
+
+ while (true) {
+ vma = find_vma_intersection(mm, start, end);
+ if (!vma)
+ break;
+
+ error = __arch_check_vma_pkey_for_write(vma);
+ if (error)
+ return error;
+
+ if (vma->vm_end >= end)
+ break;
+
+ start = vma->vm_end;
+ }
+
+ return 0;
+}
+
#endif /*_ASM_X86_PKEYS_H */
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
index 81a482c3e051..7b00689e1c24 100644
--- a/include/linux/pkeys.h
+++ b/include/linux/pkeys.h
@@ -53,6 +53,15 @@ static inline bool arch_check_pkey_alloc_flags(unsigned long flags)
return false;
return true;
}
+
+static inline int arch_check_pkey_enforce_api(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end)
+{
+ // Allow by default.
+ return 0;
+}
+
#endif /* ! CONFIG_ARCH_HAS_PKEYS */
#endif /* _LINUX_PKEYS_H */
--
2.40.1.606.ga4b1b128d6-goog
next prev parent reply other threads:[~2023-05-15 13:06 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-15 13:05 [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1 jeffxu
2023-05-15 13:05 ` [PATCH 1/6] PKEY: Introduce PKEY_ENFORCE_API flag jeffxu
2023-05-16 23:14 ` Dave Hansen
2023-05-16 23:55 ` Jeff Xu
2023-05-17 11:07 ` Stephen Röttger
2023-05-15 13:05 ` jeffxu [this message]
2023-05-18 21:43 ` [PATCH 2/6] PKEY: Add arch_check_pkey_enforce_api() Dave Hansen
2023-05-18 22:51 ` Jeff Xu
2023-05-19 0:00 ` Dave Hansen
2023-05-19 11:22 ` Stephen Röttger
2023-05-15 13:05 ` [PATCH 3/6] PKEY: Apply PKEY_ENFORCE_API to mprotect jeffxu
2023-05-16 20:07 ` Kees Cook
2023-05-16 22:23 ` Jeff Xu
2023-05-16 23:18 ` Dave Hansen
2023-05-16 23:36 ` Jeff Xu
2023-05-17 4:50 ` Jeff Xu
2023-05-15 13:05 ` [PATCH 4/6] PKEY:selftest pkey_enforce_api for mprotect jeffxu
2023-05-15 13:05 ` [PATCH 5/6] KEY: Apply PKEY_ENFORCE_API to munmap jeffxu
2023-05-16 20:06 ` Kees Cook
2023-05-16 22:24 ` Jeff Xu
2023-05-16 23:23 ` Dave Hansen
2023-05-17 0:08 ` Jeff Xu
2023-05-15 13:05 ` [PATCH 6/6] PKEY:selftest pkey_enforce_api for munmap jeffxu
2023-05-15 14:28 ` [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1 Dave Hansen
2023-05-16 7:06 ` Stephen Röttger
2023-05-16 22:41 ` Dave Hansen
2023-05-17 10:51 ` Stephen Röttger
2023-05-17 15:07 ` Dave Hansen
2023-05-17 15:21 ` Jeff Xu
2023-05-17 15:29 ` Dave Hansen
2023-05-17 23:48 ` Jeff Xu
2023-05-18 15:37 ` Dave Hansen
2023-05-18 20:20 ` Jeff Xu
2023-05-18 21:04 ` Dave Hansen
2023-05-19 11:13 ` Stephen Röttger
2023-05-24 20:15 ` Jeff Xu
2023-06-01 1:39 ` Jeff Xu
2023-06-01 16:16 ` Dave Hansen
2023-05-31 23:02 ` Jeff Xu
2023-05-16 20:08 ` Kees Cook
2023-05-16 22:17 ` Jeff Xu
2023-05-16 22:30 ` Dave Hansen
2023-05-16 23:39 ` Jeff Xu
2023-05-17 10:49 ` Stephen Röttger
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