8 files changed, 310 insertions, 44 deletions

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index aaf9c0bab..da99bbb74 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -23,6 +23,10 @@ KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 GCOV_PROFILE			:= n
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
+
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT			:= n
 
 lib-y				:= efi-stub-helper.o
 
@@ -36,7 +40,7 @@ lib-$(CONFIG_EFI_ARMSTUB)	+= arm-stub.o fdt.o string.o \
 				   $(patsubst %.c,lib-%.o,$(arm-deps))
 
 lib-$(CONFIG_ARM)		+= arm32-stub.o
-lib-$(CONFIG_ARM64)		+= arm64-stub.o
+lib-$(CONFIG_ARM64)		+= arm64-stub.o random.o
 CFLAGS_arm64-stub.o 		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 #
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 3397902e4..414deb85c 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -18,6 +18,8 @@
 
 #include "efistub.h"
 
+bool __nokaslr;
+
 static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
 {
 	static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
@@ -190,6 +192,10 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 
 	pr_efi(sys_table, "Booting Linux Kernel...\n");
 
+	status = check_platform_features(sys_table);
+	if (status != EFI_SUCCESS)
+		goto fail;
+
 	/*
 	 * Get a handle to the loaded image protocol.  This is used to get
 	 * information about the running image, such as size and the command
@@ -207,14 +213,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		pr_efi_err(sys_table, "Failed to find DRAM base\n");
 		goto fail;
 	}
-	status = handle_kernel_image(sys_table, image_addr, &image_size,
-				     &reserve_addr,
-				     &reserve_size,
-				     dram_base, image);
-	if (status != EFI_SUCCESS) {
-		pr_efi_err(sys_table, "Failed to relocate kernel\n");
-		goto fail;
-	}
 
 	/*
 	 * Get the command line from EFI, using the LOADED_IMAGE
@@ -224,7 +222,28 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
 	if (!cmdline_ptr) {
 		pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
-		goto fail_free_image;
+		goto fail;
+	}
+
+	/* check whether 'nokaslr' was passed on the command line */
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		static const u8 default_cmdline[] = CONFIG_CMDLINE;
+		const u8 *str, *cmdline = cmdline_ptr;
+
+		if (IS_ENABLED(CONFIG_CMDLINE_FORCE))
+			cmdline = default_cmdline;
+		str = strstr(cmdline, "nokaslr");
+		if (str == cmdline || (str > cmdline && *(str - 1) == ' '))
+			__nokaslr = true;
+	}
+
+	status = handle_kernel_image(sys_table, image_addr, &image_size,
+				     &reserve_addr,
+				     &reserve_size,
+				     dram_base, image);
+	if (status != EFI_SUCCESS) {
+		pr_efi_err(sys_table, "Failed to relocate kernel\n");
+		goto fail_free_cmdline;
 	}
 
 	status = efi_parse_options(cmdline_ptr);
@@ -244,7 +263,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 
 		if (status != EFI_SUCCESS) {
 			pr_efi_err(sys_table, "Failed to load device tree!\n");
-			goto fail_free_cmdline;
+			goto fail_free_image;
 		}
 	}
 
@@ -286,12 +305,11 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	efi_free(sys_table, initrd_size, initrd_addr);
 	efi_free(sys_table, fdt_size, fdt_addr);
 
-fail_free_cmdline:
-	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
-
 fail_free_image:
 	efi_free(sys_table, image_size, *image_addr);
 	efi_free(sys_table, reserve_size, reserve_addr);
+fail_free_cmdline:
+	efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
 fail:
 	return EFI_ERROR;
 }
diff --git a/drivers/firmware/efi/libstub/arm32-stub.c b/drivers/firmware/efi/libstub/arm32-stub.c
index 495ebd657..6f42be4d0 100644
--- a/drivers/firmware/efi/libstub/arm32-stub.c
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -9,6 +9,23 @@
 #include <linux/efi.h>
 #include <asm/efi.h>
 
+efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
+{
+	int block;
+
+	/* non-LPAE kernels can run anywhere */
+	if (!IS_ENABLED(CONFIG_ARM_LPAE))
+		return EFI_SUCCESS;
+
+	/* LPAE kernels need compatible hardware */
+	block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0);
+	if (block < 5) {
+		pr_efi_err(sys_table_arg, "This LPAE kernel is not supported by your CPU\n");
+		return EFI_UNSUPPORTED;
+	}
+	return EFI_SUCCESS;
+}
+
 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
 				 unsigned long *image_addr,
 				 unsigned long *image_size,
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 78dfbd34b..a90f6459f 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -12,37 +12,87 @@
 #include <linux/efi.h>
 #include <asm/efi.h>
 #include <asm/sections.h>
+#include <asm/sysreg.h>
 
-efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
-					unsigned long *image_addr,
-					unsigned long *image_size,
-					unsigned long *reserve_addr,
-					unsigned long *reserve_size,
-					unsigned long dram_base,
-					efi_loaded_image_t *image)
+#include "efistub.h"
+
+extern bool __nokaslr;
+
+efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
+{
+	u64 tg;
+
+	/* UEFI mandates support for 4 KB granularity, no need to check */
+	if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
+		return EFI_SUCCESS;
+
+	tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
+	if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
+		if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
+			pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n");
+		else
+			pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n");
+		return EFI_UNSUPPORTED;
+	}
+	return EFI_SUCCESS;
+}
+
+efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg,
+				 unsigned long *image_addr,
+				 unsigned long *image_size,
+				 unsigned long *reserve_addr,
+				 unsigned long *reserve_size,
+				 unsigned long dram_base,
+				 efi_loaded_image_t *image)
 {
 	efi_status_t status;
 	unsigned long kernel_size, kernel_memsize = 0;
-	unsigned long nr_pages;
 	void *old_image_addr = (void *)*image_addr;
 	unsigned long preferred_offset;
+	u64 phys_seed = 0;
+
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		if (!__nokaslr) {
+			status = efi_get_random_bytes(sys_table_arg,
+						      sizeof(phys_seed),
+						      (u8 *)&phys_seed);
+			if (status == EFI_NOT_FOUND) {
+				pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
+			} else if (status != EFI_SUCCESS) {
+				pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n");
+				return status;
+			}
+		} else {
+			pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n");
+		}
+	}
 
 	/*
 	 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
 	 * a 2 MB aligned base, which itself may be lower than dram_base, as
 	 * long as the resulting offset equals or exceeds it.
 	 */
-	preferred_offset = round_down(dram_base, SZ_2M) + TEXT_OFFSET;
+	preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
 	if (preferred_offset < dram_base)
-		preferred_offset += SZ_2M;
+		preferred_offset += MIN_KIMG_ALIGN;
 
-	/* Relocate the image, if required. */
 	kernel_size = _edata - _text;
-	if (*image_addr != preferred_offset) {
-		kernel_memsize = kernel_size + (_end - _edata);
+	kernel_memsize = kernel_size + (_end - _edata);
+
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
+		/*
+		 * If KASLR is enabled, and we have some randomness available,
+		 * locate the kernel at a randomized offset in physical memory.
+		 */
+		*reserve_size = kernel_memsize + TEXT_OFFSET;
+		status = efi_random_alloc(sys_table_arg, *reserve_size,
+					  MIN_KIMG_ALIGN, reserve_addr,
+					  phys_seed);
 
+		*image_addr = *reserve_addr + TEXT_OFFSET;
+	} else {
 		/*
-		 * First, try a straight allocation at the preferred offset.
+		 * Else, try a straight allocation at the preferred offset.
 		 * This will work around the issue where, if dram_base == 0x0,
 		 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
 		 * address of the allocation to be mistaken for a FAIL return
@@ -52,27 +102,31 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		if (*image_addr == preferred_offset)
+			return EFI_SUCCESS;
+
 		*image_addr = *reserve_addr = preferred_offset;
-		nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
-			   EFI_PAGE_SIZE;
+		*reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
+
 		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
-					EFI_LOADER_DATA, nr_pages,
+					EFI_LOADER_DATA,
+					*reserve_size / EFI_PAGE_SIZE,
 					(efi_physical_addr_t *)reserve_addr);
-		if (status != EFI_SUCCESS) {
-			kernel_memsize += TEXT_OFFSET;
-			status = efi_low_alloc(sys_table_arg, kernel_memsize,
-					       SZ_2M, reserve_addr);
+	}
 
-			if (status != EFI_SUCCESS) {
-				pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
-				return status;
-			}
-			*image_addr = *reserve_addr + TEXT_OFFSET;
+	if (status != EFI_SUCCESS) {
+		*reserve_size = kernel_memsize + TEXT_OFFSET;
+		status = efi_low_alloc(sys_table_arg, *reserve_size,
+				       MIN_KIMG_ALIGN, reserve_addr);
+
+		if (status != EFI_SUCCESS) {
+			pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
+			*reserve_size = 0;
+			return status;
 		}
-		memcpy((void *)*image_addr, old_image_addr, kernel_size);
-		*reserve_size = kernel_memsize;
+		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-
+	memcpy((void *)*image_addr, old_image_addr, kernel_size);
 
 	return EFI_SUCCESS;
 }
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index f07d4a67f..29ed2f9b2 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -649,6 +649,10 @@ static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
 	return dst;
 }
 
+#ifndef MAX_CMDLINE_ADDRESS
+#define MAX_CMDLINE_ADDRESS	ULONG_MAX
+#endif
+
 /*
  * Convert the unicode UEFI command line to ASCII to pass to kernel.
  * Size of memory allocated return in *cmd_line_len.
@@ -684,7 +688,8 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
 
 	options_bytes++;	/* NUL termination */
 
-	status = efi_low_alloc(sys_table_arg, options_bytes, 0, &cmdline_addr);
+	status = efi_high_alloc(sys_table_arg, options_bytes, 0,
+				&cmdline_addr, MAX_CMDLINE_ADDRESS);
 	if (status != EFI_SUCCESS)
 		return NULL;
 
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 6b6548fda..ee49cd23e 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -5,6 +5,16 @@
 /* error code which can't be mistaken for valid address */
 #define EFI_ERROR	(~0UL)
 
+/*
+ * __init annotations should not be used in the EFI stub, since the code is
+ * either included in the decompressor (x86, ARM) where they have no effect,
+ * or the whole stub is __init annotated at the section level (arm64), by
+ * renaming the sections, in which case the __init annotation will be
+ * redundant, and will result in section names like .init.init.text, and our
+ * linker script does not expect that.
+ */
+#undef __init
+
 void efi_char16_printk(efi_system_table_t *, efi_char16_t *);
 
 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, void *__image,
@@ -43,4 +53,13 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
 		     int *count);
 
+efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table,
+				  unsigned long size, u8 *out);
+
+efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
+			      unsigned long size, unsigned long align,
+			      unsigned long *addr, unsigned long random_seed);
+
+efi_status_t check_platform_features(efi_system_table_t *sys_table_arg);
+
 #endif
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index cf7b7d463..6dba78aef 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -147,6 +147,20 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 	if (status)
 		goto fdt_set_fail;
 
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
+		efi_status_t efi_status;
+
+		efi_status = efi_get_random_bytes(sys_table, sizeof(fdt_val64),
+						  (u8 *)&fdt_val64);
+		if (efi_status == EFI_SUCCESS) {
+			status = fdt_setprop(fdt, node, "kaslr-seed",
+					     &fdt_val64, sizeof(fdt_val64));
+			if (status)
+				goto fdt_set_fail;
+		} else if (efi_status != EFI_NOT_FOUND) {
+			return efi_status;
+		}
+	}
 	return EFI_SUCCESS;
 
 fdt_set_fail:
diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
new file mode 100644
index 000000000..53f6d3fe6
--- /dev/null
+++ b/drivers/firmware/efi/libstub/random.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd;  <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+struct efi_rng_protocol {
+	efi_status_t (*get_info)(struct efi_rng_protocol *,
+				 unsigned long *, efi_guid_t *);
+	efi_status_t (*get_rng)(struct efi_rng_protocol *,
+				efi_guid_t *, unsigned long, u8 *out);
+};
+
+efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
+				  unsigned long size, u8 *out)
+{
+	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
+	efi_status_t status;
+	struct efi_rng_protocol *rng;
+
+	status = efi_call_early(locate_protocol, &rng_proto, NULL,
+				(void **)&rng);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	return rng->get_rng(rng, NULL, size, out);
+}
+
+/*
+ * Return the number of slots covered by this entry, i.e., the number of
+ * addresses it covers that are suitably aligned and supply enough room
+ * for the allocation.
+ */
+static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
+					 unsigned long size,
+					 unsigned long align)
+{
+	u64 start, end;
+
+	if (md->type != EFI_CONVENTIONAL_MEMORY)
+		return 0;
+
+	start = round_up(md->phys_addr, align);
+	end = round_down(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - size,
+			 align);
+
+	if (start > end)
+		return 0;
+
+	return (end - start + 1) / align;
+}
+
+/*
+ * The UEFI memory descriptors have a virtual address field that is only used
+ * when installing the virtual mapping using SetVirtualAddressMap(). Since it
+ * is unused here, we can reuse it to keep track of each descriptor's slot
+ * count.
+ */
+#define MD_NUM_SLOTS(md)	((md)->virt_addr)
+
+efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
+			      unsigned long size,
+			      unsigned long align,
+			      unsigned long *addr,
+			      unsigned long random_seed)
+{
+	unsigned long map_size, desc_size, total_slots = 0, target_slot;
+	efi_status_t status;
+	efi_memory_desc_t *memory_map;
+	int map_offset;
+
+	status = efi_get_memory_map(sys_table_arg, &memory_map, &map_size,
+				    &desc_size, NULL, NULL);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	if (align < EFI_ALLOC_ALIGN)
+		align = EFI_ALLOC_ALIGN;
+
+	/* count the suitable slots in each memory map entry */
+	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+		efi_memory_desc_t *md = (void *)memory_map + map_offset;
+		unsigned long slots;
+
+		slots = get_entry_num_slots(md, size, align);
+		MD_NUM_SLOTS(md) = slots;
+		total_slots += slots;
+	}
+
+	/* find a random number between 0 and total_slots */
+	target_slot = (total_slots * (u16)random_seed) >> 16;
+
+	/*
+	 * target_slot is now a value in the range [0, total_slots), and so
+	 * it corresponds with exactly one of the suitable slots we recorded
+	 * when iterating over the memory map the first time around.
+	 *
+	 * So iterate over the memory map again, subtracting the number of
+	 * slots of each entry at each iteration, until we have found the entry
+	 * that covers our chosen slot. Use the residual value of target_slot
+	 * to calculate the randomly chosen address, and allocate it directly
+	 * using EFI_ALLOCATE_ADDRESS.
+	 */
+	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+		efi_memory_desc_t *md = (void *)memory_map + map_offset;
+		efi_physical_addr_t target;
+		unsigned long pages;
+
+		if (target_slot >= MD_NUM_SLOTS(md)) {
+			target_slot -= MD_NUM_SLOTS(md);
+			continue;
+		}
+
+		target = round_up(md->phys_addr, align) + target_slot * align;
+		pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
+
+		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
+					EFI_LOADER_DATA, pages, &target);
+		if (status == EFI_SUCCESS)
+			*addr = target;
+		break;
+	}
+
+	efi_call_early(free_pool, memory_map);
+
+	return status;
+}