[PATCH 18/28] mm: enforce that vmap can't map pages executable

From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@linux-foundation.org>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>,
	x86@kernel.org, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	Laura Abbott <labbott@redhat.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	Peter Zijlstra <peterz@infradead.org>,
	linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org,
	dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 18/28] mm: enforce that vmap can't map pages executable
Date: Wed,  8 Apr 2020 13:59:16 +0200	[thread overview]
Message-ID: <20200408115926.1467567-19-hch@lst.de> (raw)
In-Reply-To: <20200408115926.1467567-1-hch@lst.de>

To help enforcing the W^X protection don't allow remapping existing
pages as executable.

Based on patch from Peter Zijlstra <peterz@infradead.org>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/include/asm/pgtable_types.h | 6 ++++++
 include/asm-generic/pgtable.h        | 4 ++++
 mm/vmalloc.c                         | 2 +-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 947867f112ea..2e7c442cc618 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -282,6 +282,12 @@ typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
 
 typedef struct { pgdval_t pgd; } pgd_t;
 
+static inline pgprot_t pgprot_nx(pgprot_t prot)
+{
+	return __pgprot(pgprot_val(prot) | _PAGE_NX);
+}
+#define pgprot_nx pgprot_nx
+
 #ifdef CONFIG_X86_PAE
 
 /*
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 329b8c8ca703..8c5f9c29698b 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -491,6 +491,10 @@ static inline int arch_unmap_one(struct mm_struct *mm,
 #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
 #endif
 
+#ifndef pgprot_nx
+#define pgprot_nx(prot)	(prot)
+#endif
+
 #ifndef pgprot_noncached
 #define pgprot_noncached(prot)	(prot)
 #endif
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7356b3f07bd8..334c75251ddb 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2390,7 +2390,7 @@ void *vmap(struct page **pages, unsigned int count,
 	if (!area)
 		return NULL;
 
-	if (map_kernel_range((unsigned long)area->addr, size, prot,
+	if (map_kernel_range((unsigned long)area->addr, size, pgprot_nx(prot),
 			pages) < 0) {
 		vunmap(area->addr);
 		return NULL;
-- 
2.25.1


