mm: kmsan: maintain KMSAN metadata for page operations

Insert KMSAN hooks that make the necessary bookkeeping changes:
 - poison page shadow and origins in alloc_pages()/free_page();
 - clear page shadow and origins in clear_page(), copy_user_highpage();
 - copy page metadata in copy_highpage(), wp_page_copy();
 - handle vmap()/vunmap()/iounmap();

Link: https://lkml.kernel.org/r/20220915150417.722975-15-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 199 insertions, 0 deletions

diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 4ac62fa67a02..040111bb9f6a 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -11,6 +11,7 @@
 
 #include <linux/cacheflush.h>
 #include <linux/gfp.h>
+#include <linux/kmsan.h>
 #include <linux/mm.h>
 #include <linux/mm_types.h>
 #include <linux/slab.h>
@@ -26,6 +27,91 @@
  * skipping effects of functions like memset() inside instrumented code.
  */
 
+static unsigned long vmalloc_shadow(unsigned long addr)
+{
+	return (unsigned long)kmsan_get_metadata((void *)addr,
+						 KMSAN_META_SHADOW);
+}
+
+static unsigned long vmalloc_origin(unsigned long addr)
+{
+	return (unsigned long)kmsan_get_metadata((void *)addr,
+						 KMSAN_META_ORIGIN);
+}
+
+void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
+{
+	__vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
+	__vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
+	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
+	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
+}
+
+/*
+ * This function creates new shadow/origin pages for the physical pages mapped
+ * into the virtual memory. If those physical pages already had shadow/origin,
+ * those are ignored.
+ */
+void kmsan_ioremap_page_range(unsigned long start, unsigned long end,
+			      phys_addr_t phys_addr, pgprot_t prot,
+			      unsigned int page_shift)
+{
+	gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;
+	struct page *shadow, *origin;
+	unsigned long off = 0;
+	int nr;
+
+	if (!kmsan_enabled || kmsan_in_runtime())
+		return;
+
+	nr = (end - start) / PAGE_SIZE;
+	kmsan_enter_runtime();
+	for (int i = 0; i < nr; i++, off += PAGE_SIZE) {
+		shadow = alloc_pages(gfp_mask, 1);
+		origin = alloc_pages(gfp_mask, 1);
+		__vmap_pages_range_noflush(
+			vmalloc_shadow(start + off),
+			vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
+			PAGE_SHIFT);
+		__vmap_pages_range_noflush(
+			vmalloc_origin(start + off),
+			vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
+			PAGE_SHIFT);
+	}
+	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
+	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
+	kmsan_leave_runtime();
+}
+
+void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
+{
+	unsigned long v_shadow, v_origin;
+	struct page *shadow, *origin;
+	int nr;
+
+	if (!kmsan_enabled || kmsan_in_runtime())
+		return;
+
+	nr = (end - start) / PAGE_SIZE;
+	kmsan_enter_runtime();
+	v_shadow = (unsigned long)vmalloc_shadow(start);
+	v_origin = (unsigned long)vmalloc_origin(start);
+	for (int i = 0; i < nr;
+	     i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
+		shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
+		origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
+		__vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
+		__vunmap_range_noflush(v_origin, vmalloc_origin(end));
+		if (shadow)
+			__free_pages(shadow, 1);
+		if (origin)
+			__free_pages(origin, 1);
+	}
+	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
+	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
+	kmsan_leave_runtime();
+}
+
 /* Functions from kmsan-checks.h follow. */
 void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
 {
diff --git a/mm/kmsan/shadow.c b/mm/kmsan/shadow.c
index acc5279acc3b..8c81a059beea 100644
--- a/mm/kmsan/shadow.c
+++ b/mm/kmsan/shadow.c
@@ -145,3 +145,116 @@ void *kmsan_get_metadata(void *address, bool is_origin)
 
 	return (is_origin ? origin_ptr_for(page) : shadow_ptr_for(page)) + off;
 }
+
+void kmsan_copy_page_meta(struct page *dst, struct page *src)
+{
+	if (!kmsan_enabled || kmsan_in_runtime())
+		return;
+	if (!dst || !page_has_metadata(dst))
+		return;
+	if (!src || !page_has_metadata(src)) {
+		kmsan_internal_unpoison_memory(page_address(dst), PAGE_SIZE,
+					       /*checked*/ false);
+		return;
+	}
+
+	kmsan_enter_runtime();
+	__memcpy(shadow_ptr_for(dst), shadow_ptr_for(src), PAGE_SIZE);
+	__memcpy(origin_ptr_for(dst), origin_ptr_for(src), PAGE_SIZE);
+	kmsan_leave_runtime();
+}
+
+void kmsan_alloc_page(struct page *page, unsigned int order, gfp_t flags)
+{
+	bool initialized = (flags & __GFP_ZERO) || !kmsan_enabled;
+	struct page *shadow, *origin;
+	depot_stack_handle_t handle;
+	int pages = 1 << order;
+
+	if (!page)
+		return;
+
+	shadow = shadow_page_for(page);
+	origin = origin_page_for(page);
+
+	if (initialized) {
+		__memset(page_address(shadow), 0, PAGE_SIZE * pages);
+		__memset(page_address(origin), 0, PAGE_SIZE * pages);
+		return;
+	}
+
+	/* Zero pages allocated by the runtime should also be initialized. */
+	if (kmsan_in_runtime())
+		return;
+
+	__memset(page_address(shadow), -1, PAGE_SIZE * pages);
+	kmsan_enter_runtime();
+	handle = kmsan_save_stack_with_flags(flags, /*extra_bits*/ 0);
+	kmsan_leave_runtime();
+	/*
+	 * Addresses are page-aligned, pages are contiguous, so it's ok
+	 * to just fill the origin pages with @handle.
+	 */
+	for (int i = 0; i < PAGE_SIZE * pages / sizeof(handle); i++)
+		((depot_stack_handle_t *)page_address(origin))[i] = handle;
+}
+
+void kmsan_free_page(struct page *page, unsigned int order)
+{
+	if (!kmsan_enabled || kmsan_in_runtime())
+		return;
+	kmsan_enter_runtime();
+	kmsan_internal_poison_memory(page_address(page),
+				     PAGE_SIZE << compound_order(page),
+				     GFP_KERNEL,
+				     KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
+	kmsan_leave_runtime();
+}
+
+void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
+				    pgprot_t prot, struct page **pages,
+				    unsigned int page_shift)
+{
+	unsigned long shadow_start, origin_start, shadow_end, origin_end;
+	struct page **s_pages, **o_pages;
+	int nr, mapped;
+
+	if (!kmsan_enabled)
+		return;
+
+	shadow_start = vmalloc_meta((void *)start, KMSAN_META_SHADOW);
+	shadow_end = vmalloc_meta((void *)end, KMSAN_META_SHADOW);
+	if (!shadow_start)
+		return;
+
+	nr = (end - start) / PAGE_SIZE;
+	s_pages = kcalloc(nr, sizeof(*s_pages), GFP_KERNEL);
+	o_pages = kcalloc(nr, sizeof(*o_pages), GFP_KERNEL);
+	if (!s_pages || !o_pages)
+		goto ret;
+	for (int i = 0; i < nr; i++) {
+		s_pages[i] = shadow_page_for(pages[i]);
+		o_pages[i] = origin_page_for(pages[i]);
+	}
+	prot = __pgprot(pgprot_val(prot) | _PAGE_NX);
+	prot = PAGE_KERNEL;
+
+	origin_start = vmalloc_meta((void *)start, KMSAN_META_ORIGIN);
+	origin_end = vmalloc_meta((void *)end, KMSAN_META_ORIGIN);
+	kmsan_enter_runtime();
+	mapped = __vmap_pages_range_noflush(shadow_start, shadow_end, prot,
+					    s_pages, page_shift);
+	KMSAN_WARN_ON(mapped);
+	mapped = __vmap_pages_range_noflush(origin_start, origin_end, prot,
+					    o_pages, page_shift);
+	KMSAN_WARN_ON(mapped);
+	kmsan_leave_runtime();
+	flush_tlb_kernel_range(shadow_start, shadow_end);
+	flush_tlb_kernel_range(origin_start, origin_end);
+	flush_cache_vmap(shadow_start, shadow_end);
+	flush_cache_vmap(origin_start, origin_end);
+
+ret:
+	kfree(s_pages);
+	kfree(o_pages);
+}