diff options
| -rw-r--r-- | Documentation/admin-guide/kdump/kdump.rst | 28 | ||||
| -rw-r--r-- | kernel/Kconfig.kexec | 11 | ||||
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/crash_dump_dm_crypt.c | 154 |
4 files changed, 194 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 1f7f14c6e184..b74d3bed8fff 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -547,6 +547,34 @@ from within add_taint() whenever the value set in this bitmask matches with the bit flag being set by add_taint(). This will cause a kdump to occur at the add_taint()->panic() call. +Write the dump file to encrypted disk volume +============================================ + +CONFIG_CRASH_DM_CRYPT can be enabled to support saving the dump file to an +encrypted disk volume. User space can interact with +/sys/kernel/config/crash_dm_crypt_keys for setup, + +1. Tell the first kernel what logon keys are needed to unlock the disk volumes, + # Add key #1 + mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720 + # Add key #1's description + echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 1 + + # Add key #2 in the same way + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 2 + +2. Load the dump-capture kernel + +3. After the dump-capture kerne get booted, restore the keys to user keyring + echo yes > /sys/kernel/crash_dm_crypt_keys/restore + Contact ======= diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec index 9fea9dca15bd..c3e180d5e4fd 100644 --- a/kernel/Kconfig.kexec +++ b/kernel/Kconfig.kexec @@ -115,6 +115,17 @@ config CRASH_DUMP For s390, this option also enables zfcpdump. See also <file:Documentation/arch/s390/zfcpdump.rst> +config CRASH_DM_CRYPT + bool "Support saving crash dump to dm-crypt encrypted volume" + depends on KEXEC_FILE + depends on CRASH_DUMP + depends on DM_CRYPT + depends on CONFIGFS_FS + help + With this option enabled, user space can intereact with + /sys/kernel/config/crash_dm_crypt_keys to make the dm crypt keys + persistent for the dump-capture kernel. + config CRASH_HOTPLUG bool "Update the crash elfcorehdr on system configuration changes" default y diff --git a/kernel/Makefile b/kernel/Makefile index 434929de17ef..c7d3793107e5 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -77,6 +77,7 @@ obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o elfcorehdr.o obj-$(CONFIG_CRASH_RESERVE) += crash_reserve.o obj-$(CONFIG_KEXEC_CORE) += kexec_core.o obj-$(CONFIG_CRASH_DUMP) += crash_core.o +obj-$(CONFIG_CRASH_DM_CRYPT) += crash_dump_dm_crypt.o obj-$(CONFIG_KEXEC) += kexec.o obj-$(CONFIG_KEXEC_FILE) += kexec_file.o obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c new file mode 100644 index 000000000000..62a3c47d8b3b --- /dev/null +++ b/kernel/crash_dump_dm_crypt.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0-only +#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_DESC_MAX_LEN 128 /* maximum dm crypt key description size */ + +static unsigned int key_count; + +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 struct configfs_attribute *config_keys_attrs[] = { + &config_keys_attr_count, + 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 struct configfs_subsystem config_keys_subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = "crash_dm_crypt_keys", + .ci_type = &config_keys_type, + }, + }, +}; + +static int __init configfs_dmcrypt_keys_init(void) +{ + int ret; + + 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); |