Merge tag 'x86_kdump_for_v6.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 kdump updates from Borislav Petkov:

 - Add the ability to pass early an RNG seed to the kernel from the boot
   loader

 - Add the ability to pass the IMA measurement of kernel and bootloader
   to the kexec-ed kernel

* tag 'x86_kdump_for_v6.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/setup: Use rng seeds from setup_data
  x86/kexec: Carry forward IMA measurement log on kexec

Author: torvalds

arch/x86/Kconfig

@@ -2010,6 +2010,7 @@ config KEXEC
 config KEXEC_FILE
 	bool "kexec file based system call"
 	select KEXEC_CORE
+	select HAVE_IMA_KEXEC if IMA
 	depends on X86_64
 	depends on CRYPTO=y
 	depends on CRYPTO_SHA256=y

arch/x86/include/uapi/asm/bootparam.h

@@ -11,11 +11,12 @@
 #define SETUP_APPLE_PROPERTIES		5
 #define SETUP_JAILHOUSE			6
 #define SETUP_CC_BLOB			7
+#define SETUP_IMA			8
+#define SETUP_RNG_SEED			9
+#define SETUP_ENUM_MAX			SETUP_RNG_SEED
 
 #define SETUP_INDIRECT			(1<<31)
-
-/* SETUP_INDIRECT | max(SETUP_*) */
-#define SETUP_TYPE_MAX			(SETUP_INDIRECT | SETUP_CC_BLOB)
+#define SETUP_TYPE_MAX			(SETUP_ENUM_MAX | SETUP_INDIRECT)
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK	0x07FF
@@ -172,6 +173,14 @@ struct jailhouse_setup_data {
 	} __attribute__((packed)) v2;
 } __attribute__((packed));
 
+/*
+ * IMA buffer setup data information from the previous kernel during kexec
+ */
+struct ima_setup_data {
+	__u64 addr;
+	__u64 size;
+} __attribute__((packed));
+
 /* The so-called "zeropage" */
 struct boot_params {
 	struct screen_info screen_info;			/* 0x000 */

arch/x86/kernel/e820.c

@@ -1017,10 +1017,10 @@ void __init e820__reserve_setup_data(void)
 		e820__range_update(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
 
 		/*
-		 * SETUP_EFI is supplied by kexec and does not need to be
-		 * reserved.
+		 * SETUP_EFI and SETUP_IMA are supplied by kexec and do not need
+		 * to be reserved.
 		 */
-		if (data->type != SETUP_EFI)
+		if (data->type != SETUP_EFI && data->type != SETUP_IMA)
 			e820__range_update_kexec(pa_data,
 						 sizeof(*data) + data->len,
 						 E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);

arch/x86/kernel/kexec-bzimage64.c

@@ -18,6 +18,7 @@
 #include <linux/mm.h>
 #include <linux/efi.h>
 #include <linux/verification.h>
+#include <linux/random.h>
 
 #include <asm/bootparam.h>
 #include <asm/setup.h>
@@ -110,6 +111,26 @@ static int setup_e820_entries(struct boot_params *params)
 	return 0;
 }
 
+enum { RNG_SEED_LENGTH = 32 };
+
+static void
+setup_rng_seed(struct boot_params *params, unsigned long params_load_addr,
+	       unsigned int rng_seed_setup_data_offset)
+{
+	struct setup_data *sd = (void *)params + rng_seed_setup_data_offset;
+	unsigned long setup_data_phys;
+
+	if (!rng_is_initialized())
+		return;
+
+	sd->type = SETUP_RNG_SEED;
+	sd->len = RNG_SEED_LENGTH;
+	get_random_bytes(sd->data, RNG_SEED_LENGTH);
+	setup_data_phys = params_load_addr + rng_seed_setup_data_offset;
+	sd->next = params->hdr.setup_data;
+	params->hdr.setup_data = setup_data_phys;
+}
+
 #ifdef CONFIG_EFI
 static int setup_efi_info_memmap(struct boot_params *params,
 				  unsigned long params_load_addr,
@@ -186,11 +207,38 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
 }
 #endif /* CONFIG_EFI */
 
+static void
+setup_ima_state(const struct kimage *image, struct boot_params *params,
+		unsigned long params_load_addr,
+		unsigned int ima_setup_data_offset)
+{
+#ifdef CONFIG_IMA_KEXEC
+	struct setup_data *sd = (void *)params + ima_setup_data_offset;
+	unsigned long setup_data_phys;
+	struct ima_setup_data *ima;
+
+	if (!image->ima_buffer_size)
+		return;
+
+	sd->type = SETUP_IMA;
+	sd->len = sizeof(*ima);
+
+	ima = (void *)sd + sizeof(struct setup_data);
+	ima->addr = image->ima_buffer_addr;
+	ima->size = image->ima_buffer_size;
+
+	/* Add setup data */
+	setup_data_phys = params_load_addr + ima_setup_data_offset;
+	sd->next = params->hdr.setup_data;
+	params->hdr.setup_data = setup_data_phys;
+#endif /* CONFIG_IMA_KEXEC */
+}
+
 static int
 setup_boot_parameters(struct kimage *image, struct boot_params *params,
 		      unsigned long params_load_addr,
 		      unsigned int efi_map_offset, unsigned int efi_map_sz,
-		      unsigned int efi_setup_data_offset)
+		      unsigned int setup_data_offset)
 {
 	unsigned int nr_e820_entries;
 	unsigned long long mem_k, start, end;
@@ -245,8 +293,22 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
 #ifdef CONFIG_EFI
 	/* Setup EFI state */
 	setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
-			efi_setup_data_offset);
+			setup_data_offset);
+	setup_data_offset += sizeof(struct setup_data) +
+			sizeof(struct efi_setup_data);
 #endif
+
+	if (IS_ENABLED(CONFIG_IMA_KEXEC)) {
+		/* Setup IMA log buffer state */
+		setup_ima_state(image, params, params_load_addr,
+				setup_data_offset);
+		setup_data_offset += sizeof(struct setup_data) +
+				     sizeof(struct ima_setup_data);
+	}
+
+	/* Setup RNG seed */
+	setup_rng_seed(params, params_load_addr, setup_data_offset);
+
 	/* Setup EDD info */
 	memcpy(params->eddbuf, boot_params.eddbuf,
 				EDDMAXNR * sizeof(struct edd_info));
@@ -401,7 +463,13 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
 	params_cmdline_sz = ALIGN(params_cmdline_sz, 16);
 	kbuf.bufsz = params_cmdline_sz + ALIGN(efi_map_sz, 16) +
 				sizeof(struct setup_data) +
-				sizeof(struct efi_setup_data);
+				sizeof(struct efi_setup_data) +
+				sizeof(struct setup_data) +
+				RNG_SEED_LENGTH;
+
+	if (IS_ENABLED(CONFIG_IMA_KEXEC))
+		kbuf.bufsz += sizeof(struct setup_data) +
+			      sizeof(struct ima_setup_data);
 
 	params = kzalloc(kbuf.bufsz, GFP_KERNEL);
 	if (!params)

arch/x86/kernel/setup.c

@@ -11,6 +11,7 @@
 #include <linux/dma-map-ops.h>
 #include <linux/dmi.h>
 #include <linux/efi.h>
+#include <linux/ima.h>
 #include <linux/init_ohci1394_dma.h>
 #include <linux/initrd.h>
 #include <linux/iscsi_ibft.h>
@@ -23,6 +24,7 @@
 #include <linux/usb/xhci-dbgp.h>
 #include <linux/static_call.h>
 #include <linux/swiotlb.h>
+#include <linux/random.h>
 
 #include <uapi/linux/mount.h>
 
@@ -140,6 +142,11 @@ __visible unsigned long mmu_cr4_features __ro_after_init;
 __visible unsigned long mmu_cr4_features __ro_after_init = X86_CR4_PAE;
 #endif
 
+#ifdef CONFIG_IMA
+static phys_addr_t ima_kexec_buffer_phys;
+static size_t ima_kexec_buffer_size;
+#endif
+
 /* Boot loader ID and version as integers, for the benefit of proc_dointvec */
 int bootloader_type, bootloader_version;
 
@@ -330,6 +337,60 @@ static void __init reserve_initrd(void)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+static void __init add_early_ima_buffer(u64 phys_addr)
+{
+#ifdef CONFIG_IMA
+	struct ima_setup_data *data;
+
+	data = early_memremap(phys_addr + sizeof(struct setup_data), sizeof(*data));
+	if (!data) {
+		pr_warn("setup: failed to memremap ima_setup_data entry\n");
+		return;
+	}
+
+	if (data->size) {
+		memblock_reserve(data->addr, data->size);
+		ima_kexec_buffer_phys = data->addr;
+		ima_kexec_buffer_size = data->size;
+	}
+
+	early_memunmap(data, sizeof(*data));
+#else
+	pr_warn("Passed IMA kexec data, but CONFIG_IMA not set. Ignoring.\n");
+#endif
+}
+
+#if defined(CONFIG_HAVE_IMA_KEXEC) && !defined(CONFIG_OF_FLATTREE)
+int __init ima_free_kexec_buffer(void)
+{
+	int rc;
+
+	if (!ima_kexec_buffer_size)
+		return -ENOENT;
+
+	rc = memblock_phys_free(ima_kexec_buffer_phys,
+				ima_kexec_buffer_size);
+	if (rc)
+		return rc;
+
+	ima_kexec_buffer_phys = 0;
+	ima_kexec_buffer_size = 0;
+
+	return 0;
+}
+
+int __init ima_get_kexec_buffer(void **addr, size_t *size)
+{
+	if (!ima_kexec_buffer_size)
+		return -ENOENT;
+
+	*addr = __va(ima_kexec_buffer_phys);
+	*size = ima_kexec_buffer_size;
+
+	return 0;
+}
+#endif
+
 static void __init parse_setup_data(void)
 {
 	struct setup_data *data;
@@ -355,6 +416,18 @@ static void __init parse_setup_data(void)
 		case SETUP_EFI:
 			parse_efi_setup(pa_data, data_len);
 			break;
+		case SETUP_IMA:
+			add_early_ima_buffer(pa_data);
+			break;
+		case SETUP_RNG_SEED:
+			data = early_memremap(pa_data, data_len);
+			add_bootloader_randomness(data->data, data->len);
+			/* Zero seed for forward secrecy. */
+			memzero_explicit(data->data, data->len);
+			/* Zero length in case we find ourselves back here by accident. */
+			memzero_explicit(&data->len, sizeof(data->len));
+			early_memunmap(data, data_len);
+			break;
 		default:
 			break;
 		}

drivers/of/kexec.c

@@ -9,6 +9,7 @@
  *  Copyright (C) 2016  IBM Corporation
  */
 
+#include <linux/ima.h>
 #include <linux/kernel.h>
 #include <linux/kexec.h>
 #include <linux/memblock.h>
@@ -115,23 +116,21 @@ static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
 	return 0;
 }
 
+#ifdef CONFIG_HAVE_IMA_KEXEC
 /**
  * ima_get_kexec_buffer - get IMA buffer from the previous kernel
  * @addr:	On successful return, set to point to the buffer contents.
  * @size:	On successful return, set to the buffer size.
  *
  * Return: 0 on success, negative errno on error.
  */
-int ima_get_kexec_buffer(void **addr, size_t *size)
+int __init ima_get_kexec_buffer(void **addr, size_t *size)
 {
 	int ret, len;
 	unsigned long tmp_addr;
 	size_t tmp_size;
 	const void *prop;
 
-	if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
-		return -ENOTSUPP;
-
 	prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
 	if (!prop)
 		return -ENOENT;
@@ -149,16 +148,13 @@ int ima_get_kexec_buffer(void **addr, size_t *size)
 /**
  * ima_free_kexec_buffer - free memory used by the IMA buffer
  */
-int ima_free_kexec_buffer(void)
+int __init ima_free_kexec_buffer(void)
 {
 	int ret;
 	unsigned long addr;
 	size_t size;
 	struct property *prop;
 
-	if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
-		return -ENOTSUPP;
-
 	prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
 	if (!prop)
 		return -ENOENT;
@@ -173,6 +169,7 @@ int ima_free_kexec_buffer(void)
 
 	return memblock_phys_free(addr, size);
 }
+#endif
 
 /**
  * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt

include/linux/ima.h

@@ -140,6 +140,11 @@ static inline int ima_measure_critical_data(const char *event_label,
 
 #endif /* CONFIG_IMA */
 
+#ifdef CONFIG_HAVE_IMA_KEXEC
+int __init ima_free_kexec_buffer(void);
+int __init ima_get_kexec_buffer(void **addr, size_t *size);
+#endif
+
 #ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
 extern bool arch_ima_get_secureboot(void);
 extern const char * const *arch_get_ima_policy(void);

include/linux/of.h

@@ -441,8 +441,6 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 				   unsigned long initrd_load_addr,
 				   unsigned long initrd_len,
 				   const char *cmdline, size_t extra_fdt_size);
-int ima_get_kexec_buffer(void **addr, size_t *size);
-int ima_free_kexec_buffer(void);
 #else /* CONFIG_OF */
 
 static inline void of_core_init(void)

security/integrity/ima/ima_kexec.c

@@ -137,7 +137,7 @@ void ima_add_kexec_buffer(struct kimage *image)
 /*
  * Restore the measurement list from the previous kernel.
  */
-void ima_load_kexec_buffer(void)
+void __init ima_load_kexec_buffer(void)
 {
 	void *kexec_buffer = NULL;
 	size_t kexec_buffer_size = 0;