kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged

HW_TAGS KASAN relies on ARM Memory Tagging Extension (MTE).  With MTE, a
memory region must be mapped as MT_NORMAL_TAGGED to allow setting memory
tags via MTE-specific instructions.

Add proper protection bits to vmalloc() allocations.  These allocations
are always backed by page_alloc pages, so the tags will actually be
getting set on the corresponding physical memory.

Link: https://lkml.kernel.org/r/983fc33542db2f6b1e77b34ca23448d4640bbb9e.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arm64/include/asm/vmalloc.h b/arch/arm64/include/asm/vmalloc.h
index b918550..38fafff 100644 (file)
--- a/arch/arm64/include/asm/vmalloc.h
+++ b/arch/arm64/include/asm/vmalloc.h
@@ -25,4 +25,10 @@ static inline bool arch_vmap_pmd_supported(pgprot_t prot)
 
 #endif
 
+#define arch_vmap_pgprot_tagged arch_vmap_pgprot_tagged
+static inline pgprot_t arch_vmap_pgprot_tagged(pgprot_t prot)
+{
+       return pgprot_tagged(prot);
+}
+
 #endif /* _ASM_ARM64_VMALLOC_H */

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 2ca95c7..3b1df7d 100644 (file)
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -115,6 +115,13 @@ static inline int arch_vmap_pte_supported_shift(unsigned long size)
 }
 #endif
 
+#ifndef arch_vmap_pgprot_tagged
+static inline pgprot_t arch_vmap_pgprot_tagged(pgprot_t prot)
+{
+       return prot;
+}
+#endif
+
 /*
  *     Highlevel APIs for driver use
  */

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 1ab1f1b..8530d86 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3128,6 +3128,15 @@ again:
                goto fail;
        }
 
+       /*
+        * Modify protection bits to allow tagging.
+        * This must be done before mapping by __vmalloc_area_node().
+        */
+       if (kasan_hw_tags_enabled() &&
+           pgprot_val(prot) == pgprot_val(PAGE_KERNEL))
+               prot = arch_vmap_pgprot_tagged(prot);
+
+       /* Allocate physical pages and map them into vmalloc space. */
        addr = __vmalloc_area_node(area, gfp_mask, prot, shift, node);
        if (!addr)
                goto fail;