Messages in this thread |  | | Date | Wed, 17 Jan 2024 15:39:50 +0800 | | From | Coiby Xu <> | | Subject | Re: Re: [PATCH v2 2/5] crash_dump: save the dm crypt key temporarily |
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On Tue, Jan 16, 2024 at 11:40:53AM +0100, Ondrej Kozina wrote: >On 10/01/2024 08:15, Coiby Xu wrote: >>User space is supposed to write the key description to >>/sys/kernel/crash_dm_crypt_key so the kernel will read the key and save >>a temporary copy for later user. User space has 2 minutes at maximum to >>load the kdump initrd before the key gets wiped. And after kdump >>retrieves the key, the key will be wiped immediately. >> >>Signed-off-by: Coiby Xu <coxu@redhat.com> >>--- >> include/linux/crash_core.h | 7 +- >> include/linux/kexec.h | 4 ++ >> kernel/Makefile | 2 +- >> kernel/crash_dump_dm_crypt.c | 121 +++++++++++++++++++++++++++++++++++ >> kernel/ksysfs.c | 23 ++++++- >> 5 files changed, 153 insertions(+), 4 deletions(-) >> create mode 100644 kernel/crash_dump_dm_crypt.c >> >>diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h >>index 5126a4fecb44..7078eda6418d 100644 >>--- a/include/linux/crash_core.h >>+++ b/include/linux/crash_core.h >>@@ -125,6 +125,12 @@ static inline void __init reserve_crashkernel_generic(char *cmdline, >> {} >> #endif >>+struct kimage; >>+ >>+int crash_sysfs_dm_crypt_key_write(const char *key_des, size_t count); >>+int crash_pass_temp_dm_crypt_key(void **addr, unsigned long *sz); >>+int crash_load_dm_crypt_key(struct kimage *image); >>+ >> /* Alignment required for elf header segment */ >> #define ELF_CORE_HEADER_ALIGN 4096 >>@@ -140,7 +146,6 @@ extern int crash_exclude_mem_range(struct crash_mem *mem, >> extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map, >> void **addr, unsigned long *sz); >>-struct kimage; >> struct kexec_segment; >> #define KEXEC_CRASH_HP_NONE 0 >>diff --git a/include/linux/kexec.h b/include/linux/kexec.h >>index 6f4626490ebf..bf7ab1e927ef 100644 >>--- a/include/linux/kexec.h >>+++ b/include/linux/kexec.h >>@@ -366,6 +366,10 @@ struct kimage { >> void *elf_headers; >> unsigned long elf_headers_sz; >> unsigned long elf_load_addr; >>+ >>+ /* dm crypt key buffer */ >>+ unsigned long dm_crypt_key_addr; >>+ unsigned long dm_crypt_key_sz; >> }; >> /* kexec interface functions */ >>diff --git a/kernel/Makefile b/kernel/Makefile >>index 3947122d618b..48859bf63db5 100644 >>--- a/kernel/Makefile >>+++ b/kernel/Makefile >>@@ -119,7 +119,7 @@ obj-$(CONFIG_PERF_EVENTS) += events/ >> obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o >> obj-$(CONFIG_PADATA) += padata.o >>-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o >>+obj-$(CONFIG_CRASH_DUMP) += crash_dump.o crash_dump_dm_crypt.o >> obj-$(CONFIG_JUMP_LABEL) += jump_label.o >> obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o >> obj-$(CONFIG_TORTURE_TEST) += torture.o >>diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c >>new file mode 100644 >>index 000000000000..3a0b0b773598 >>--- /dev/null >>+++ b/kernel/crash_dump_dm_crypt.c >>@@ -0,0 +1,121 @@ >>+// SPDX-License-Identifier: GPL-2.0-only >>+#include <keys/user-type.h> >>+#include <linux/crash_dump.h> >>+ >>+static u8 *dm_crypt_key; >>+static unsigned int dm_crypt_key_size; >>+ >>+void wipe_dm_crypt_key(void) >>+{ >>+ if (dm_crypt_key) { >>+ memset(dm_crypt_key, 0, dm_crypt_key_size * sizeof(u8)); >>+ kfree(dm_crypt_key); >>+ dm_crypt_key = NULL; >>+ } >>+} >>+ >>+static void _wipe_dm_crypt_key(struct work_struct *dummy) >>+{ >>+ wipe_dm_crypt_key(); >>+} >>+ >>+static DECLARE_DELAYED_WORK(wipe_dm_crypt_key_work, _wipe_dm_crypt_key); >>+ >>+static unsigned __read_mostly wipe_key_delay = 120; /* 2 mins */ >>+ >>+static int crash_save_temp_dm_crypt_key(const char *key_desc, size_t count) >>+{ >>+ const struct user_key_payload *ukp; >>+ struct key *key; >>+ >>+ if (dm_crypt_key) { >>+ memset(dm_crypt_key, 0, dm_crypt_key_size * sizeof(u8)); >>+ kfree(dm_crypt_key); >>+ } >>+ >>+ pr_debug("Requesting key %s", key_desc); >>+ key = request_key(&key_type_user, key_desc, NULL); > >If we don't read the key copy form userspace (my reply to top level >message) you could use key_type_logon here.
I'll use key_type_logon, thanks!
-- Best regards, Coiby
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