+ crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory.patch added to mm-nonmm-unstable branch

+ crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: crash_dump: store dm crypt keys in kdump reserved memory
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Coiby Xu <coxu@redhat.com>
Subject: crash_dump: store dm crypt keys in kdump reserved memory
Date: Fri, 2 May 2025 09:12:37 +0800

When the kdump kernel image and initrd are loaded, the dm crypts keys will
be read from keyring and then stored in kdump reserved memory.

Assume a key won't exceed 256 bytes thus MAX_KEY_SIZE=256 according to
"cryptsetup benchmark".

Link: https://lkml.kernel.org/r/20250502011246.99238-4-coxu@redhat.com
Signed-off-by: Coiby Xu <coxu@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Jan Pazdziora <jpazdziora@redhat.com>
Cc: Liu Pingfan <kernelfans@gmail.com>
Cc: Milan Broz <gmazyland@gmail.com>
Cc: Ondrej Kozina <okozina@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/crash_core.h   |    6 +
 include/linux/kexec.h        |    4 
 kernel/crash_dump_dm_crypt.c |  133 +++++++++++++++++++++++++++++++++
 3 files changed, 142 insertions(+), 1 deletion(-)

--- a/include/linux/crash_core.h~crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory
+++ a/include/linux/crash_core.h
@@ -34,7 +34,11 @@ static inline void arch_kexec_protect_cr
 static inline void arch_kexec_unprotect_crashkres(void) { }
 #endif
 
-
+#ifdef CONFIG_CRASH_DM_CRYPT
+int crash_load_dm_crypt_keys(struct kimage *image);
+#else
+static inline int crash_load_dm_crypt_keys(struct kimage *image) {return 0; }
+#endif
 
 #ifndef arch_crash_handle_hotplug_event
 static inline void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) { }
--- a/include/linux/kexec.h~crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory
+++ a/include/linux/kexec.h
@@ -410,6 +410,10 @@ struct kimage {
 	void *elf_headers;
 	unsigned long elf_headers_sz;
 	unsigned long elf_load_addr;
+
+	/* dm crypt keys buffer */
+	unsigned long dm_crypt_keys_addr;
+	unsigned long dm_crypt_keys_sz;
 };
 
 /* kexec interface functions */
--- a/kernel/crash_dump_dm_crypt.c~crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory
+++ a/kernel/crash_dump_dm_crypt.c
@@ -1,14 +1,62 @@
 // 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/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);
+}
+
+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;
@@ -130,6 +178,91 @@ static struct configfs_subsystem config_
 	},
 };
 
+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;
+	}
+
+	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;
_

Patches currently in -mm which might be from coxu@redhat.com are

kexec_file-allow-to-place-kexec_buf-randomly.patch
crash_dump-make-dm-crypt-keys-persist-for-the-kdump-kernel.patch
crash_dump-store-dm-crypt-keys-in-kdump-reserved-memory.patch
crash_dump-reuse-saved-dm-crypt-keys-for-cpu-memory-hot-plugging.patch
crash_dump-retrieve-dm-crypt-keys-in-kdump-kernel.patch
revert-x86-mm-remove-unused-__set_memory_prot.patch
x86-crash-pass-dm-crypt-keys-to-kdump-kernel.patch
x86-crash-make-the-page-that-stores-the-dm-crypt-keys-inaccessible.patch