1 files changed, 464 insertions, 0 deletions
diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
new file mode 100644
index 000000000000..401423ba477d
--- /dev/null
+++ b/kernel/crash_dump_dm_crypt.c
@@ -0,0 +1,464 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/key.h>
+#include <linux/keyctl.h>
+#include <keys/user-type.h>
+#include <linux/crash_dump.h>
+#include <linux/cc_platform.h>
+#include <linux/configfs.h>
+#include <linux/module.h>
+
+#define KEY_NUM_MAX 128	/* maximum dm crypt keys */
+#define KEY_SIZE_MAX 256	/* maximum dm crypt key size */
+#define KEY_DESC_MAX_LEN 128	/* maximum dm crypt key description size */
+
+static unsigned int key_count;
+
+struct dm_crypt_key {
+	unsigned int key_size;
+	char key_desc[KEY_DESC_MAX_LEN];
+	u8 data[KEY_SIZE_MAX];
+};
+
+static struct keys_header {
+	unsigned int total_keys;
+	struct dm_crypt_key keys[] __counted_by(total_keys);
+} *keys_header;
+
+static size_t get_keys_header_size(size_t total_keys)
+{
+	return struct_size(keys_header, keys, total_keys);
+}
+
+unsigned long long dm_crypt_keys_addr;
+EXPORT_SYMBOL_GPL(dm_crypt_keys_addr);
+
+static int __init setup_dmcryptkeys(char *arg)
+{
+	char *end;
+
+	if (!arg)
+		return -EINVAL;
+	dm_crypt_keys_addr = memparse(arg, &end);
+	if (end > arg)
+		return 0;
+
+	dm_crypt_keys_addr = 0;
+	return -EINVAL;
+}
+
+early_param("dmcryptkeys", setup_dmcryptkeys);
+
+/*
+ * Architectures may override this function to read dm crypt keys
+ */
+ssize_t __weak dm_crypt_keys_read(char *buf, size_t count, u64 *ppos)
+{
+	struct kvec kvec = { .iov_base = buf, .iov_len = count };
+	struct iov_iter iter;
+
+	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	return read_from_oldmem(&iter, count, ppos, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
+}
+
+static int add_key_to_keyring(struct dm_crypt_key *dm_key,
+			      key_ref_t keyring_ref)
+{
+	key_ref_t key_ref;
+	int r;
+
+	/* create or update the requested key and add it to the target keyring */
+	key_ref = key_create_or_update(keyring_ref, "user", dm_key->key_desc,
+				       dm_key->data, dm_key->key_size,
+				       KEY_USR_ALL, KEY_ALLOC_IN_QUOTA);
+
+	if (!IS_ERR(key_ref)) {
+		r = key_ref_to_ptr(key_ref)->serial;
+		key_ref_put(key_ref);
+		kexec_dprintk("Success adding key %s", dm_key->key_desc);
+	} else {
+		r = PTR_ERR(key_ref);
+		kexec_dprintk("Error when adding key");
+	}
+
+	key_ref_put(keyring_ref);
+	return r;
+}
+
+static void get_keys_from_kdump_reserved_memory(void)
+{
+	struct keys_header *keys_header_loaded;
+
+	arch_kexec_unprotect_crashkres();
+
+	keys_header_loaded = kmap_local_page(pfn_to_page(
+		kexec_crash_image->dm_crypt_keys_addr >> PAGE_SHIFT));
+
+	memcpy(keys_header, keys_header_loaded, get_keys_header_size(key_count));
+	kunmap_local(keys_header_loaded);
+	arch_kexec_protect_crashkres();
+}
+
+static int restore_dm_crypt_keys_to_thread_keyring(void)
+{
+	struct dm_crypt_key *key;
+	size_t keys_header_size;
+	key_ref_t keyring_ref;
+	u64 addr;
+
+	/* find the target keyring (which must be writable) */
+	keyring_ref =
+		lookup_user_key(KEY_SPEC_USER_KEYRING, 0x01, KEY_NEED_WRITE);
+	if (IS_ERR(keyring_ref)) {
+		kexec_dprintk("Failed to get the user keyring\n");
+		return PTR_ERR(keyring_ref);
+	}
+
+	addr = dm_crypt_keys_addr;
+	dm_crypt_keys_read((char *)&key_count, sizeof(key_count), &addr);
+	if (key_count < 0 || key_count > KEY_NUM_MAX) {
+		kexec_dprintk("Failed to read the number of dm-crypt keys\n");
+		return -1;
+	}
+
+	kexec_dprintk("There are %u keys\n", key_count);
+	addr = dm_crypt_keys_addr;
+
+	keys_header_size = get_keys_header_size(key_count);
+	keys_header = kzalloc(keys_header_size, GFP_KERNEL);
+	if (!keys_header)
+		return -ENOMEM;
+
+	dm_crypt_keys_read((char *)keys_header, keys_header_size, &addr);
+
+	for (int i = 0; i < keys_header->total_keys; i++) {
+		key = &keys_header->keys[i];
+		kexec_dprintk("Get key (size=%u)\n", key->key_size);
+		add_key_to_keyring(key, keyring_ref);
+	}
+
+	return 0;
+}
+
+static int read_key_from_user_keying(struct dm_crypt_key *dm_key)
+{
+	const struct user_key_payload *ukp;
+	struct key *key;
+
+	kexec_dprintk("Requesting logon key %s", dm_key->key_desc);
+	key = request_key(&key_type_logon, dm_key->key_desc, NULL);
+
+	if (IS_ERR(key)) {
+		pr_warn("No such logon key %s\n", dm_key->key_desc);
+		return PTR_ERR(key);
+	}
+
+	ukp = user_key_payload_locked(key);
+	if (!ukp)
+		return -EKEYREVOKED;
+
+	if (ukp->datalen > KEY_SIZE_MAX) {
+		pr_err("Key size %u exceeds maximum (%u)\n", ukp->datalen, KEY_SIZE_MAX);
+		return -EINVAL;
+	}
+
+	memcpy(dm_key->data, ukp->data, ukp->datalen);
+	dm_key->key_size = ukp->datalen;
+	kexec_dprintk("Get dm crypt key (size=%u) %s: %8ph\n", dm_key->key_size,
+		      dm_key->key_desc, dm_key->data);
+	return 0;
+}
+
+struct config_key {
+	struct config_item item;
+	const char *description;
+};
+
+static inline struct config_key *to_config_key(struct config_item *item)
+{
+	return container_of(item, struct config_key, item);
+}
+
+static ssize_t config_key_description_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%s\n", to_config_key(item)->description);
+}
+
+static ssize_t config_key_description_store(struct config_item *item,
+					    const char *page, size_t count)
+{
+	struct config_key *config_key = to_config_key(item);
+	size_t len;
+	int ret;
+
+	ret = -EINVAL;
+	len = strcspn(page, "\n");
+
+	if (len > KEY_DESC_MAX_LEN) {
+		pr_err("The key description shouldn't exceed %u characters", KEY_DESC_MAX_LEN);
+		return ret;
+	}
+
+	if (!len)
+		return ret;
+
+	kfree(config_key->description);
+	ret = -ENOMEM;
+	config_key->description = kmemdup_nul(page, len, GFP_KERNEL);
+	if (!config_key->description)
+		return ret;
+
+	return count;
+}
+
+CONFIGFS_ATTR(config_key_, description);
+
+static struct configfs_attribute *config_key_attrs[] = {
+	&config_key_attr_description,
+	NULL,
+};
+
+static void config_key_release(struct config_item *item)
+{
+	kfree(to_config_key(item));
+	key_count--;
+}
+
+static struct configfs_item_operations config_key_item_ops = {
+	.release = config_key_release,
+};
+
+static const struct config_item_type config_key_type = {
+	.ct_item_ops = &config_key_item_ops,
+	.ct_attrs = config_key_attrs,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_item *config_keys_make_item(struct config_group *group,
+						 const char *name)
+{
+	struct config_key *config_key;
+
+	if (key_count > KEY_NUM_MAX) {
+		pr_err("Only %u keys at maximum to be created\n", KEY_NUM_MAX);
+		return ERR_PTR(-EINVAL);
+	}
+
+	config_key = kzalloc(sizeof(struct config_key), GFP_KERNEL);
+	if (!config_key)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&config_key->item, name, &config_key_type);
+
+	key_count++;
+
+	return &config_key->item;
+}
+
+static ssize_t config_keys_count_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", key_count);
+}
+
+CONFIGFS_ATTR_RO(config_keys_, count);
+
+static bool is_dm_key_reused;
+
+static ssize_t config_keys_reuse_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", is_dm_key_reused);
+}
+
+static ssize_t config_keys_reuse_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	if (!kexec_crash_image || !kexec_crash_image->dm_crypt_keys_addr) {
+		kexec_dprintk(
+			"dm-crypt keys haven't be saved to crash-reserved memory\n");
+		return -EINVAL;
+	}
+
+	if (kstrtobool(page, &is_dm_key_reused))
+		return -EINVAL;
+
+	if (is_dm_key_reused)
+		get_keys_from_kdump_reserved_memory();
+
+	return count;
+}
+
+CONFIGFS_ATTR(config_keys_, reuse);
+
+static struct configfs_attribute *config_keys_attrs[] = {
+	&config_keys_attr_count,
+	&config_keys_attr_reuse,
+	NULL,
+};
+
+/*
+ * Note that, since no extra work is required on ->drop_item(),
+ * no ->drop_item() is provided.
+ */
+static struct configfs_group_operations config_keys_group_ops = {
+	.make_item = config_keys_make_item,
+};
+
+static const struct config_item_type config_keys_type = {
+	.ct_group_ops = &config_keys_group_ops,
+	.ct_attrs = config_keys_attrs,
+	.ct_owner = THIS_MODULE,
+};
+
+static bool restore;
+
+static ssize_t config_keys_restore_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", restore);
+}
+
+static ssize_t config_keys_restore_store(struct config_item *item,
+					  const char *page, size_t count)
+{
+	if (!restore)
+		restore_dm_crypt_keys_to_thread_keyring();
+
+	if (kstrtobool(page, &restore))
+		return -EINVAL;
+
+	return count;
+}
+
+CONFIGFS_ATTR(config_keys_, restore);
+
+static struct configfs_attribute *kdump_config_keys_attrs[] = {
+	&config_keys_attr_restore,
+	NULL,
+};
+
+static const struct config_item_type kdump_config_keys_type = {
+	.ct_attrs = kdump_config_keys_attrs,
+	.ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem config_keys_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "crash_dm_crypt_keys",
+			.ci_type = &config_keys_type,
+		},
+	},
+};
+
+static int build_keys_header(void)
+{
+	struct config_item *item = NULL;
+	struct config_key *key;
+	int i, r;
+
+	if (keys_header != NULL)
+		kvfree(keys_header);
+
+	keys_header = kzalloc(get_keys_header_size(key_count), GFP_KERNEL);
+	if (!keys_header)
+		return -ENOMEM;
+
+	keys_header->total_keys = key_count;
+
+	i = 0;
+	list_for_each_entry(item, &config_keys_subsys.su_group.cg_children,
+			    ci_entry) {
+		if (item->ci_type != &config_key_type)
+			continue;
+
+		key = to_config_key(item);
+
+		if (!key->description) {
+			pr_warn("No key description for key %s\n", item->ci_name);
+			return -EINVAL;
+		}
+
+		strscpy(keys_header->keys[i].key_desc, key->description,
+			KEY_DESC_MAX_LEN);
+		r = read_key_from_user_keying(&keys_header->keys[i]);
+		if (r != 0) {
+			kexec_dprintk("Failed to read key %s\n",
+				      keys_header->keys[i].key_desc);
+			return r;
+		}
+		i++;
+		kexec_dprintk("Found key: %s\n", item->ci_name);
+	}
+
+	return 0;
+}
+
+int crash_load_dm_crypt_keys(struct kimage *image)
+{
+	struct kexec_buf kbuf = {
+		.image = image,
+		.buf_min = 0,
+		.buf_max = ULONG_MAX,
+		.top_down = false,
+		.random = true,
+	};
+	int r;
+
+
+	if (key_count <= 0) {
+		kexec_dprintk("No dm-crypt keys\n");
+		return -ENOENT;
+	}
+
+	if (!is_dm_key_reused) {
+		image->dm_crypt_keys_addr = 0;
+		r = build_keys_header();
+		if (r)
+			return r;
+	}
+
+	kbuf.buffer = keys_header;
+	kbuf.bufsz = get_keys_header_size(key_count);
+
+	kbuf.memsz = kbuf.bufsz;
+	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
+	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+	r = kexec_add_buffer(&kbuf);
+	if (r) {
+		kvfree((void *)kbuf.buffer);
+		return r;
+	}
+	image->dm_crypt_keys_addr = kbuf.mem;
+	image->dm_crypt_keys_sz = kbuf.bufsz;
+	kexec_dprintk(
+		"Loaded dm crypt keys to kexec_buffer bufsz=0x%lx memsz=0x%lx\n",
+		kbuf.bufsz, kbuf.memsz);
+
+	return r;
+}
+
+static int __init configfs_dmcrypt_keys_init(void)
+{
+	int ret;
+
+	if (is_kdump_kernel()) {
+		config_keys_subsys.su_group.cg_item.ci_type =
+			&kdump_config_keys_type;
+	}
+
+	config_group_init(&config_keys_subsys.su_group);
+	mutex_init(&config_keys_subsys.su_mutex);
+	ret = configfs_register_subsystem(&config_keys_subsys);
+	if (ret) {
+		pr_err("Error %d while registering subsystem %s\n", ret,
+		       config_keys_subsys.su_group.cg_item.ci_namebuf);
+		goto out_unregister;
+	}
+
+	return 0;
+
+out_unregister:
+	configfs_unregister_subsystem(&config_keys_subsys);
+
+	return ret;
+}
+
+module_init(configfs_dmcrypt_keys_init);