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From:   Yu-cheng Yu <yu-cheng.yu@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,
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        Arnd Bergmann <arnd@arndb.de>,
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        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>,
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        Randy Dunlap <rdunlap@infradead.org>,
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        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Weijiang Yang <weijiang.yang@intel.com>,
        Pengfei Xu <pengfei.xu@intel.com>,
        Haitao Huang <haitao.huang@intel.com>
Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Will Deacon <will@kernel.org>
Subject: [PATCH v24 29/30] mm: Update arch_validate_flags() to include vma anonymous
Date:   Thu,  1 Apr 2021 15:11:03 -0700
Message-Id: <20210401221104.31584-30-yu-cheng.yu@intel.com>
In-Reply-To: <20210401221104.31584-1-yu-cheng.yu@intel.com>
References: <20210401221104.31584-1-yu-cheng.yu@intel.com>
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When newer VM flags are being created, such as VM_MTE, it becomes necessary
for mmap/mprotect to verify if certain flags are being applied to an
anonymous VMA.

To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
is specified [1], and then using the flag in arch_validate_flags().

Another approach is passing vma_is_anonymous() to arch_validate_flags().
To prepare the introduction of PROT_SHSTK, which creates a shadow stack
mapping and can only be applied to an anonymous VMA, update arch_validate_
flags() to include anonymous VMA information.

[1] commit 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()"),

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/mman.h | 4 ++--
 arch/sparc/include/asm/mman.h | 4 ++--
 include/linux/mman.h          | 2 +-
 mm/mmap.c                     | 2 +-
 mm/mprotect.c                 | 2 +-
 5 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index e3e28f7daf62..44add1a09041 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h
@@ -74,7 +74,7 @@ static inline bool arch_validate_prot(unsigned long prot,
 }
 #define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr)
 
-static inline bool arch_validate_flags(unsigned long vm_flags)
+static inline bool arch_validate_flags(unsigned long vm_flags, bool is_anon)
 {
 	if (!system_supports_mte())
 		return true;
@@ -82,6 +82,6 @@ static inline bool arch_validate_flags(unsigned long vm_flags)
 	/* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */
 	return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED);
 }
-#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
+#define arch_validate_flags(vm_flags, is_anon) arch_validate_flags(vm_flags, is_anon)
 
 #endif /* ! __ASM_MMAN_H__ */
diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h
index 274217e7ed70..4a897c8a3f1a 100644
--- a/arch/sparc/include/asm/mman.h
+++ b/arch/sparc/include/asm/mman.h
@@ -60,11 +60,11 @@ static inline int sparc_validate_prot(unsigned long prot, unsigned long addr)
 	return 1;
 }
 
-#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
+#define arch_validate_flags(vm_flags, is_anon) arch_validate_flags(vm_flags, is_anon)
 /* arch_validate_flags() - Ensure combination of flags is valid for a
  *	VMA.
  */
-static inline bool arch_validate_flags(unsigned long vm_flags)
+static inline bool arch_validate_flags(unsigned long vm_flags, bool is_anon)
 {
 	/* If ADI is being enabled on this VMA, check for ADI
 	 * capability on the platform and ensure VMA is suitable
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 629cefc4ecba..a22ed4495d13 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -114,7 +114,7 @@ static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
  *
  * Returns true if the VM_* flags are valid.
  */
-static inline bool arch_validate_flags(unsigned long flags)
+static inline bool arch_validate_flags(unsigned long flags, bool is_anonymous)
 {
 	return true;
 }
diff --git a/mm/mmap.c b/mm/mmap.c
index 7b2992ef8ee0..db849e3ed9d3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1850,7 +1850,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	}
 
 	/* Allow architectures to sanity-check the vm_flags */
-	if (!arch_validate_flags(vma->vm_flags)) {
+	if (!arch_validate_flags(vma->vm_flags, vma_is_anonymous(vma))) {
 		error = -EINVAL;
 		if (file)
 			goto unmap_and_free_vma;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 550448dc5ff1..621d73e3667d 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -611,7 +611,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 		}
 
 		/* Allow architectures to sanity-check the new flags */
-		if (!arch_validate_flags(newflags)) {
+		if (!arch_validate_flags(newflags, vma_is_anonymous(vma))) {
 			error = -EINVAL;
 			goto out;
 		}
-- 
2.21.0