1 files changed, 438 insertions, 0 deletions
diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
new file mode 100644
index 000000000..d59152721
--- /dev/null
+++ b/drivers/firmware/efi/esrt.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * esrt.c
+ *
+ * This module exports EFI System Resource Table (ESRT) entries into userspace
+ * through the sysfs file system. The ESRT provides a read-only catalog of
+ * system components for which the system accepts firmware upgrades via UEFI's
+ * "Capsule Update" feature. This module allows userland utilities to evaluate
+ * what firmware updates can be applied to this system, and potentially arrange
+ * for those updates to occur.
+ *
+ * Data is currently found below /sys/firmware/efi/esrt/...
+ */
+#define pr_fmt(fmt) "esrt: " fmt
+
+#include <linux/capability.h>
+#include <linux/device.h>
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/list.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include <asm/io.h>
+#include <asm/early_ioremap.h>
+
+struct efi_system_resource_entry_v1 {
+	efi_guid_t	fw_class;
+	u32		fw_type;
+	u32		fw_version;
+	u32		lowest_supported_fw_version;
+	u32		capsule_flags;
+	u32		last_attempt_version;
+	u32		last_attempt_status;
+};
+
+/*
+ * _count and _version are what they seem like.  _max is actually just
+ * accounting info for the firmware when creating the table; it should never
+ * have been exposed to us.  To wit, the spec says:
+ * The maximum number of resource array entries that can be within the
+ * table without reallocating the table, must not be zero.
+ * Since there's no guidance about what that means in terms of memory layout,
+ * it means nothing to us.
+ */
+struct efi_system_resource_table {
+	u32	fw_resource_count;
+	u32	fw_resource_count_max;
+	u64	fw_resource_version;
+	u8	entries[];
+};
+
+static phys_addr_t esrt_data;
+static size_t esrt_data_size;
+
+static struct efi_system_resource_table *esrt;
+
+struct esre_entry {
+	union {
+		struct efi_system_resource_entry_v1 *esre1;
+	} esre;
+
+	struct kobject kobj;
+	struct list_head list;
+};
+
+/* global list of esre_entry. */
+static LIST_HEAD(entry_list);
+
+/* entry attribute */
+struct esre_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct esre_entry *entry, char *buf);
+	ssize_t (*store)(struct esre_entry *entry,
+			 const char *buf, size_t count);
+};
+
+static struct esre_entry *to_entry(struct kobject *kobj)
+{
+	return container_of(kobj, struct esre_entry, kobj);
+}
+
+static struct esre_attribute *to_attr(struct attribute *attr)
+{
+	return container_of(attr, struct esre_attribute, attr);
+}
+
+static ssize_t esre_attr_show(struct kobject *kobj,
+			      struct attribute *_attr, char *buf)
+{
+	struct esre_entry *entry = to_entry(kobj);
+	struct esre_attribute *attr = to_attr(_attr);
+
+	/* Don't tell normal users what firmware versions we've got... */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	return attr->show(entry, buf);
+}
+
+static const struct sysfs_ops esre_attr_ops = {
+	.show = esre_attr_show,
+};
+
+/* Generic ESRT Entry ("ESRE") support. */
+static ssize_t fw_class_show(struct esre_entry *entry, char *buf)
+{
+	char *str = buf;
+
+	efi_guid_to_str(&entry->esre.esre1->fw_class, str);
+	str += strlen(str);
+	str += sprintf(str, "\n");
+
+	return str - buf;
+}
+
+static struct esre_attribute esre_fw_class = __ATTR_RO_MODE(fw_class, 0400);
+
+#define esre_attr_decl(name, size, fmt) \
+static ssize_t name##_show(struct esre_entry *entry, char *buf) \
+{ \
+	return sprintf(buf, fmt "\n", \
+		       le##size##_to_cpu(entry->esre.esre1->name)); \
+} \
+\
+static struct esre_attribute esre_##name = __ATTR_RO_MODE(name, 0400)
+
+esre_attr_decl(fw_type, 32, "%u");
+esre_attr_decl(fw_version, 32, "%u");
+esre_attr_decl(lowest_supported_fw_version, 32, "%u");
+esre_attr_decl(capsule_flags, 32, "0x%x");
+esre_attr_decl(last_attempt_version, 32, "%u");
+esre_attr_decl(last_attempt_status, 32, "%u");
+
+static struct attribute *esre1_attrs[] = {
+	&esre_fw_class.attr,
+	&esre_fw_type.attr,
+	&esre_fw_version.attr,
+	&esre_lowest_supported_fw_version.attr,
+	&esre_capsule_flags.attr,
+	&esre_last_attempt_version.attr,
+	&esre_last_attempt_status.attr,
+	NULL
+};
+static void esre_release(struct kobject *kobj)
+{
+	struct esre_entry *entry = to_entry(kobj);
+
+	list_del(&entry->list);
+	kfree(entry);
+}
+
+static struct kobj_type esre1_ktype = {
+	.release = esre_release,
+	.sysfs_ops = &esre_attr_ops,
+	.default_attrs = esre1_attrs,
+};
+
+
+static struct kobject *esrt_kobj;
+static struct kset *esrt_kset;
+
+static int esre_create_sysfs_entry(void *esre, int entry_num)
+{
+	struct esre_entry *entry;
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->kobj.kset = esrt_kset;
+
+	if (esrt->fw_resource_version == 1) {
+		int rc = 0;
+
+		entry->esre.esre1 = esre;
+		rc = kobject_init_and_add(&entry->kobj, &esre1_ktype, NULL,
+					  "entry%d", entry_num);
+		if (rc) {
+			kobject_put(&entry->kobj);
+			return rc;
+		}
+	}
+
+	list_add_tail(&entry->list, &entry_list);
+	return 0;
+}
+
+/* support for displaying ESRT fields at the top level */
+#define esrt_attr_decl(name, size, fmt) \
+static ssize_t name##_show(struct kobject *kobj, \
+				  struct kobj_attribute *attr, char *buf)\
+{ \
+	return sprintf(buf, fmt "\n", le##size##_to_cpu(esrt->name)); \
+} \
+\
+static struct kobj_attribute esrt_##name = __ATTR_RO_MODE(name, 0400)
+
+esrt_attr_decl(fw_resource_count, 32, "%u");
+esrt_attr_decl(fw_resource_count_max, 32, "%u");
+esrt_attr_decl(fw_resource_version, 64, "%llu");
+
+static struct attribute *esrt_attrs[] = {
+	&esrt_fw_resource_count.attr,
+	&esrt_fw_resource_count_max.attr,
+	&esrt_fw_resource_version.attr,
+	NULL,
+};
+
+static inline int esrt_table_exists(void)
+{
+	if (!efi_enabled(EFI_CONFIG_TABLES))
+		return 0;
+	if (efi.esrt == EFI_INVALID_TABLE_ADDR)
+		return 0;
+	return 1;
+}
+
+static umode_t esrt_attr_is_visible(struct kobject *kobj,
+				    struct attribute *attr, int n)
+{
+	if (!esrt_table_exists())
+		return 0;
+	return attr->mode;
+}
+
+static const struct attribute_group esrt_attr_group = {
+	.attrs = esrt_attrs,
+	.is_visible = esrt_attr_is_visible,
+};
+
+/*
+ * remap the table, validate it, mark it reserved and unmap it.
+ */
+void __init efi_esrt_init(void)
+{
+	void *va;
+	struct efi_system_resource_table tmpesrt;
+	size_t size, max, entry_size, entries_size;
+	efi_memory_desc_t md;
+	int rc;
+	phys_addr_t end;
+
+	if (!efi_enabled(EFI_MEMMAP))
+		return;
+
+	pr_debug("esrt-init: loading.\n");
+	if (!esrt_table_exists())
+		return;
+
+	rc = efi_mem_desc_lookup(efi.esrt, &md);
+	if (rc < 0 ||
+	    (!(md.attribute & EFI_MEMORY_RUNTIME) &&
+	     md.type != EFI_BOOT_SERVICES_DATA &&
+	     md.type != EFI_RUNTIME_SERVICES_DATA)) {
+		pr_warn("ESRT header is not in the memory map.\n");
+		return;
+	}
+
+	max = efi_mem_desc_end(&md);
+	if (max < efi.esrt) {
+		pr_err("EFI memory descriptor is invalid. (esrt: %p max: %p)\n",
+		       (void *)efi.esrt, (void *)max);
+		return;
+	}
+
+	size = sizeof(*esrt);
+	max -= efi.esrt;
+
+	if (max < size) {
+		pr_err("ESRT header doesn't fit on single memory map entry. (size: %zu max: %zu)\n",
+		       size, max);
+		return;
+	}
+
+	va = early_memremap(efi.esrt, size);
+	if (!va) {
+		pr_err("early_memremap(%p, %zu) failed.\n", (void *)efi.esrt,
+		       size);
+		return;
+	}
+
+	memcpy(&tmpesrt, va, sizeof(tmpesrt));
+	early_memunmap(va, size);
+
+	if (tmpesrt.fw_resource_version != 1) {
+		pr_err("Unsupported ESRT version %lld.\n",
+		       tmpesrt.fw_resource_version);
+		return;
+	}
+
+	entry_size = sizeof(struct efi_system_resource_entry_v1);
+	if (tmpesrt.fw_resource_count > 0 && max - size < entry_size) {
+		pr_err("ESRT memory map entry can only hold the header. (max: %zu size: %zu)\n",
+		       max - size, entry_size);
+		return;
+	}
+
+	/*
+	 * The format doesn't really give us any boundary to test here,
+	 * so I'm making up 128 as the max number of individually updatable
+	 * components we support.
+	 * 128 should be pretty excessive, but there's still some chance
+	 * somebody will do that someday and we'll need to raise this.
+	 */
+	if (tmpesrt.fw_resource_count > 128) {
+		pr_err("ESRT says fw_resource_count has very large value %d.\n",
+		       tmpesrt.fw_resource_count);
+		return;
+	}
+
+	/*
+	 * We know it can't be larger than N * sizeof() here, and N is limited
+	 * by the previous test to a small number, so there's no overflow.
+	 */
+	entries_size = tmpesrt.fw_resource_count * entry_size;
+	if (max < size + entries_size) {
+		pr_err("ESRT does not fit on single memory map entry (size: %zu max: %zu)\n",
+		       size, max);
+		return;
+	}
+
+	size += entries_size;
+
+	esrt_data = (phys_addr_t)efi.esrt;
+	esrt_data_size = size;
+
+	end = esrt_data + size;
+	pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
+	if (md.type == EFI_BOOT_SERVICES_DATA)
+		efi_mem_reserve(esrt_data, esrt_data_size);
+
+	pr_debug("esrt-init: loaded.\n");
+}
+
+static int __init register_entries(void)
+{
+	struct efi_system_resource_entry_v1 *v1_entries = (void *)esrt->entries;
+	int i, rc;
+
+	if (!esrt_table_exists())
+		return 0;
+
+	for (i = 0; i < le32_to_cpu(esrt->fw_resource_count); i++) {
+		void *esre = NULL;
+		if (esrt->fw_resource_version == 1) {
+			esre = &v1_entries[i];
+		} else {
+			pr_err("Unsupported ESRT version %lld.\n",
+			       esrt->fw_resource_version);
+			return -EINVAL;
+		}
+
+		rc = esre_create_sysfs_entry(esre, i);
+		if (rc < 0) {
+			pr_err("ESRT entry creation failed with error %d.\n",
+			       rc);
+			return rc;
+		}
+	}
+	return 0;
+}
+
+static void cleanup_entry_list(void)
+{
+	struct esre_entry *entry, *next;
+
+	list_for_each_entry_safe(entry, next, &entry_list, list) {
+		kobject_put(&entry->kobj);
+	}
+}
+
+static int __init esrt_sysfs_init(void)
+{
+	int error;
+
+	pr_debug("esrt-sysfs: loading.\n");
+	if (!esrt_data || !esrt_data_size)
+		return -ENOSYS;
+
+	esrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
+	if (!esrt) {
+		pr_err("memremap(%pa, %zu) failed.\n", &esrt_data,
+		       esrt_data_size);
+		return -ENOMEM;
+	}
+
+	esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
+	if (!esrt_kobj) {
+		pr_err("Firmware table registration failed.\n");
+		error = -ENOMEM;
+		goto err;
+	}
+
+	error = sysfs_create_group(esrt_kobj, &esrt_attr_group);
+	if (error) {
+		pr_err("Sysfs attribute export failed with error %d.\n",
+		       error);
+		goto err_remove_esrt;
+	}
+
+	esrt_kset = kset_create_and_add("entries", NULL, esrt_kobj);
+	if (!esrt_kset) {
+		pr_err("kset creation failed.\n");
+		error = -ENOMEM;
+		goto err_remove_group;
+	}
+
+	error = register_entries();
+	if (error)
+		goto err_cleanup_list;
+
+	pr_debug("esrt-sysfs: loaded.\n");
+
+	return 0;
+err_cleanup_list:
+	cleanup_entry_list();
+	kset_unregister(esrt_kset);
+err_remove_group:
+	sysfs_remove_group(esrt_kobj, &esrt_attr_group);
+err_remove_esrt:
+	kobject_put(esrt_kobj);
+err:
+	memunmap(esrt);
+	esrt = NULL;
+	return error;
+}
+device_initcall(esrt_sysfs_init);
+
+/*
+MODULE_AUTHOR("Peter Jones <pjones@redhat.com>");
+MODULE_DESCRIPTION("EFI System Resource Table support");
+MODULE_LICENSE("GPL");
+*/