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charset="utf-8" Currently, kexec_buf is placed in order which means for the same machine, the info in the kexec_buf is always located at the same position each time the machine is booted. This may cause a risk for sensitive information like LUKS volume key. Now struct kexec_buf has a new field random which indicates it's supposed to be placed in a random position. Suggested-by: Jan Pazdziora Signed-off-by: Coiby Xu --- include/linux/kexec.h | 2 ++ kernel/kexec_file.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index f0e9f8eda7a3..cc81b8a903ab 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -171,6 +171,7 @@ int kexec_image_post_load_cleanup_default(struct kimage= *image); * @buf_min: The buffer can't be placed below this address. * @buf_max: The buffer can't be placed above this address. * @top_down: Allocate from top of memory. + * @random: Place the buffer at a random position. */ struct kexec_buf { struct kimage *image; @@ -182,6 +183,7 @@ struct kexec_buf { unsigned long buf_min; unsigned long buf_max; bool top_down; + bool random; }; =20 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 3d64290d24c9..06b77f9ac4cc 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include "kexec_internal.h" @@ -437,6 +438,16 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, = initrd_fd, return ret; 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R. Silva" , linux-hardening@vger.kernel.org (open list:KERNEL HARDENING (not covered by other areas):Keyword:\b__counted_by\b) Subject: [PATCH v4 2/7] crash_dump: make dm crypt keys persist for the kdump kernel Date: Thu, 23 May 2024 13:04:43 +0800 Message-ID: <20240523050451.788754-3-coxu@redhat.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240523050451.788754-1-coxu@redhat.com> References: <20240523050451.788754-1-coxu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A sysfs /sys/kernel/crash_dm_crypt_keys is provided for user space to make the dm crypt keys persist for the kdump kernel. User space can send the following commands, - "init KEY_NUM" Initialize needed structures - "record KEY_DESC" Record a key description. The key must be a logon key. User space can also read this API to learn about current state. Signed-off-by: Coiby Xu --- include/linux/crash_core.h | 5 +- kernel/Kconfig.kexec | 8 +++ kernel/Makefile | 1 + kernel/crash_dump_dm_crypt.c | 113 +++++++++++++++++++++++++++++++++++ kernel/ksysfs.c | 22 +++++++ 5 files changed, 148 insertions(+), 1 deletion(-) create mode 100644 kernel/crash_dump_dm_crypt.c diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index 44305336314e..6bff1c24efa3 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -34,7 +34,10 @@ static inline void arch_kexec_protect_crashkres(void) { } static inline void arch_kexec_unprotect_crashkres(void) { } #endif =20 - +#ifdef CONFIG_CRASH_DM_CRYPT +int crash_sysfs_dm_crypt_keys_read(char *buf); +int crash_sysfs_dm_crypt_keys_write(const char *buf, size_t count); +#endif =20 #ifndef arch_crash_handle_hotplug_event static inline void arch_crash_handle_hotplug_event(struct kimage *image, v= oid *arg) { } diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec index 6c34e63c88ff..88525ad1c80a 100644 --- a/kernel/Kconfig.kexec +++ b/kernel/Kconfig.kexec @@ -116,6 +116,14 @@ config CRASH_DUMP For s390, this option also enables zfcpdump. See also =20 +config CRASH_DM_CRYPT + bool "Support saving crash dump to dm-crypt encrypted volume" + depends on CRASH_DUMP + help + With this option enabled, user space can intereact with + /sys/kernel/crash_dm_crypt_keys to make the dm crypt keys + persistent for the crash dump kernel. + config CRASH_HOTPLUG bool "Update the crash elfcorehdr on system configuration changes" default y diff --git a/kernel/Makefile b/kernel/Makefile index 3c13240dfc9f..f2e5b3e86d12 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -72,6 +72,7 @@ obj-$(CONFIG_VMCORE_INFO) +=3D vmcore_info.o elfcorehdr.o obj-$(CONFIG_CRASH_RESERVE) +=3D crash_reserve.o obj-$(CONFIG_KEXEC_CORE) +=3D kexec_core.o obj-$(CONFIG_CRASH_DUMP) +=3D crash_core.o +obj-$(CONFIG_CRASH_DM_CRYPT) +=3D crash_dump_dm_crypt.o obj-$(CONFIG_KEXEC) +=3D kexec.o obj-$(CONFIG_KEXEC_FILE) +=3D kexec_file.o obj-$(CONFIG_KEXEC_ELF) +=3D 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..78809189084a --- /dev/null +++ b/kernel/crash_dump_dm_crypt.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include + +#define KEY_NUM_MAX 128 +#define KEY_SIZE_MAX 256 + +// The key scription has the format: cryptsetup:UUID 11+36+1(NULL)=3D48 +#define KEY_DESC_LEN 48 + +static char *STATE_STR[] =3D {"fresh", "initialized", "recorded", "loaded"= }; +static enum STATE_ENUM { + FRESH =3D 0, + INITIALIZED, + RECORDED, + LOADED, +} state; + +static unsigned int key_count; +static size_t keys_header_size; + +struct dm_crypt_key { + unsigned int key_size; + char key_desc[KEY_DESC_LEN]; + u8 data[KEY_SIZE_MAX]; +}; + +static struct keys_header { + unsigned int key_count; + struct dm_crypt_key keys[] __counted_by(key_count); +} *keys_header; + +static size_t get_keys_header_size(struct keys_header *keys_header, + size_t key_count) +{ + return struct_size(keys_header, keys, key_count); +} + +static int init(const char *buf) +{ + unsigned int total_keys; + char dummy[5]; + + if (sscanf(buf, "%4s %u", dummy, &total_keys) !=3D 2) + return -EINVAL; + + if (key_count > KEY_NUM_MAX) { + pr_err("Exceed the maximum number of keys (KEY_NUM_MAX=3D%u)\n", + KEY_NUM_MAX); + return -EINVAL; + } + + keys_header_size =3D get_keys_header_size(keys_header, total_keys); + key_count =3D 0; + + keys_header =3D kzalloc(keys_header_size, GFP_KERNEL); + if (!keys_header) + return -ENOMEM; + + keys_header->key_count =3D total_keys; + state =3D INITIALIZED; + return 0; +} + +static int record_key_desc(const char *buf, struct dm_crypt_key *dm_key) +{ + char key_desc[KEY_DESC_LEN]; + char dummy[7]; + + if (state !=3D INITIALIZED) + pr_err("Please send the cmd 'init ' first\n"); + + if (sscanf(buf, "%6s %s", dummy, key_desc) !=3D 2) + return -EINVAL; + + if (key_count >=3D keys_header->key_count) { + pr_warn("Already have %u keys", key_count); + return -EINVAL; + } + + strscpy(dm_key->key_desc, key_desc, KEY_DESC_LEN); + pr_debug("Key%d (%s) recorded\n", key_count, dm_key->key_desc); + key_count++; + + if (key_count =3D=3D keys_header->key_count) + state =3D RECORDED; + + return 0; +} + +static int process_cmd(const char *buf, size_t count) +{ + if (strncmp(buf, "init ", 5) =3D=3D 0) + return init(buf); + else if (strncmp(buf, "record ", 7) =3D=3D 0) + return record_key_desc(buf, &keys_header->keys[key_count]); + + return -EINVAL; +} + +int crash_sysfs_dm_crypt_keys_write(const char *buf, size_t count) +{ + if (!is_kdump_kernel()) + return process_cmd(buf, count); + return -EINVAL; +} +EXPORT_SYMBOL(crash_sysfs_dm_crypt_keys_write); + +int crash_sysfs_dm_crypt_keys_read(char *buf) +{ + return sprintf(buf, "%s\n", STATE_STR[state]); +} +EXPORT_SYMBOL(crash_sysfs_dm_crypt_keys_read); diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 07fb5987b42b..2ba4dcbf5816 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -167,6 +167,25 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj, } KERNEL_ATTR_RO(vmcoreinfo); =20 +#ifdef CONFIG_CRASH_DM_CRYPT +static ssize_t crash_dm_crypt_keys_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return crash_sysfs_dm_crypt_keys_read(buf); +} + +static ssize_t crash_dm_crypt_keys_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int ret; + + ret =3D crash_sysfs_dm_crypt_keys_write(buf, count); + return ret < 0 ? ret : count; +} +KERNEL_ATTR_RW(crash_dm_crypt_keys); +#endif /* CONFIG_CRASH_DM_CRYPT */ + #ifdef CONFIG_CRASH_HOTPLUG static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) @@ -271,6 +290,9 @@ static struct attribute * kernel_attrs[] =3D { #endif #ifdef CONFIG_VMCORE_INFO &vmcoreinfo_attr.attr, +#ifdef CONFIG_CRASH_DM_CRYPT + &crash_dm_crypt_keys_attr.attr, +#endif #ifdef CONFIG_CRASH_HOTPLUG &crash_elfcorehdr_size_attr.attr, #endif --=20 2.45.0 From nobody Wed Feb 11 12:54:45 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1687113B59A for ; 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charset="utf-8" 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. Signed-off-by: Coiby Xu --- include/linux/crash_core.h | 3 ++ include/linux/crash_dump.h | 2 + include/linux/kexec.h | 4 ++ kernel/crash_dump_dm_crypt.c | 87 ++++++++++++++++++++++++++++++++++++ 4 files changed, 96 insertions(+) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index 6bff1c24efa3..ab20829d0bc9 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -37,6 +37,9 @@ static inline void arch_kexec_unprotect_crashkres(void) {= } #ifdef CONFIG_CRASH_DM_CRYPT int crash_sysfs_dm_crypt_keys_read(char *buf); int crash_sysfs_dm_crypt_keys_write(const char *buf, size_t count); +int crash_load_dm_crypt_keys(struct kimage *image); +#else +static inline int crash_load_dm_crypt_keys(struct kimage *image) {return 0= ; } #endif =20 #ifndef arch_crash_handle_hotplug_event diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h index acc55626afdc..dfd8e4fe6129 100644 --- a/include/linux/crash_dump.h +++ b/include/linux/crash_dump.h @@ -15,6 +15,8 @@ extern unsigned long long elfcorehdr_addr; extern unsigned long long elfcorehdr_size; =20 +extern unsigned long long dm_crypt_keys_addr; + #ifdef CONFIG_CRASH_DUMP extern int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *= size); extern void elfcorehdr_free(unsigned long long addr); diff --git a/include/linux/kexec.h b/include/linux/kexec.h index cc81b8a903ab..bd40f4208e1f 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -370,6 +370,10 @@ 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; }; =20 /* kexec interface functions */ diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 78809189084a..89fec768fba8 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -1,4 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-only +#include +#include #include #include =20 @@ -111,3 +113,88 @@ int crash_sysfs_dm_crypt_keys_read(char *buf) return sprintf(buf, "%s\n", STATE_STR[state]); } EXPORT_SYMBOL(crash_sysfs_dm_crypt_keys_read); + +static int read_key_from_user_keying(struct dm_crypt_key *dm_key) +{ + const struct user_key_payload *ukp; + struct key *key; + + pr_debug("Requesting key %s", dm_key->key_desc); + key =3D request_key(&key_type_logon, dm_key->key_desc, NULL); + + if (IS_ERR(key)) { + pr_warn("No such key %s\n", dm_key->key_desc); + return PTR_ERR(key); + } + + ukp =3D user_key_payload_locked(key); + if (!ukp) + return -EKEYREVOKED; + + memcpy(dm_key->data, ukp->data, ukp->datalen); + dm_key->key_size =3D ukp->datalen; + pr_debug("Get dm crypt key (size=3D%u) %s: %8ph\n", dm_key->key_size, + dm_key->key_desc, dm_key->data); + return 0; +} + +static int build_keys_header(void) +{ + int i, r; + + for (i =3D 0; i < key_count; i++) { + r =3D read_key_from_user_keying(&keys_header->keys[i]); + if (r !=3D 0) { + pr_err("Failed to read key %s\n", keys_header->keys[i].key_desc); + return r; + } + } + + return 0; +} + +int crash_load_dm_crypt_keys(struct kimage *image) +{ + struct kexec_buf kbuf =3D { + .image =3D image, + .buf_min =3D 0, + .buf_max =3D ULONG_MAX, + .top_down =3D false, + .random =3D true, + }; 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charset="utf-8" When there is CPU/memory hot-plugging, the kdump kernel image and initrd will be reloaded. The user space can write the "reuse" command to /sys/kernel/crash_dm_crypt_key so the stored keys can be re-saved again. Note currently only x86 (commit ea53ad9cf73b ("x86/crash: add x86 crash hotplug support")) and ppc (WIP) supports the new infrastructure (commit 247262756121 ("crash: add generic infrastructure for crash hotplug support")). If the new infrastructure get extended to all arches, this patch can be dropped. Signed-off-by: Coiby Xu --- kernel/crash_dump_dm_crypt.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 89fec768fba8..b4dc881cc867 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -10,12 +10,13 @@ // The key scription has the format: cryptsetup:UUID 11+36+1(NULL)=3D48 #define KEY_DESC_LEN 48 =20 -static char *STATE_STR[] =3D {"fresh", "initialized", "recorded", "loaded"= }; +static char *STATE_STR[] =3D {"fresh", "initialized", "recorded", "loaded"= , "reuse"}; static enum STATE_ENUM { FRESH =3D 0, INITIALIZED, RECORDED, LOADED, + REUSE, } state; =20 static unsigned int key_count; @@ -90,12 +91,31 @@ static int record_key_desc(const char *buf, struct dm_c= rypt_key *dm_key) return 0; } =20 +static void get_keys_from_kdump_reserved_memory(void) +{ + struct keys_header *keys_header_loaded; + + arch_kexec_unprotect_crashkres(); + + keys_header_loaded =3D kmap_local_page(pfn_to_page( + kexec_crash_image->dm_crypt_keys_addr >> PAGE_SHIFT)); 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charset="utf-8" Crash kernel will retrieve the dm crypt keys based on the dmcryptkeys command line parameter. When user space writes the key description to /sys/kernel/crash_dm_crypt_key, the crash kernel will save the encryption keys to the user keyring. Then user space e.g. cryptsetup's --volume-key-keyring API can use it to unlock the encrypted device. Signed-off-by: Coiby Xu --- include/linux/crash_core.h | 1 + kernel/crash_dump_dm_crypt.c | 99 +++++++++++++++++++++++++++++++++++- 2 files changed, 99 insertions(+), 1 deletion(-) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index ab20829d0bc9..d7308b6e83f4 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -38,6 +38,7 @@ static inline void arch_kexec_unprotect_crashkres(void) {= } int crash_sysfs_dm_crypt_keys_read(char *buf); int crash_sysfs_dm_crypt_keys_write(const char *buf, size_t count); int crash_load_dm_crypt_keys(struct kimage *image); +ssize_t dm_crypt_keys_read(char *buf, size_t count, u64 *ppos); #else static inline int crash_load_dm_crypt_keys(struct kimage *image) {return 0= ; } #endif diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index b4dc881cc867..dd818581858b 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -33,12 +33,67 @@ static struct keys_header { struct dm_crypt_key keys[] __counted_by(key_count); } *keys_header; =20 +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 =3D memparse(arg, &end); + if (end > arg) + return 0; + + dm_crypt_keys_addr =3D 0; + return -EINVAL; +} + +early_param("dmcryptkeys", setup_dmcryptkeys); + static size_t get_keys_header_size(struct keys_header *keys_header, size_t key_count) { return struct_size(keys_header, keys, key_count); } =20 +/* + * Architectures may override this function to read dm crypt key + */ +ssize_t __weak dm_crypt_keys_read(char *buf, size_t count, u64 *ppos) +{ + struct kvec kvec =3D { .iov_base =3D buf, .iov_len =3D count }; + struct iov_iter iter; + + iov_iter_kvec(&iter, READ, &kvec, 1, count); + return read_from_oldmem(&iter, count, ppos, false); +} + +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 =3D 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 =3D key_ref_to_ptr(key_ref)->serial; + key_ref_put(key_ref); + pr_alert("Success adding key %s", dm_key->key_desc); + } else { + r =3D PTR_ERR(key_ref); + pr_alert("Error when adding key"); + } + + key_ref_put(keyring_ref); + return r; +} + static int init(const char *buf) { unsigned int total_keys; @@ -120,11 +175,53 @@ static int process_cmd(const char *buf, size_t count) return -EINVAL; } =20 +static int restore_dm_crypt_keys_to_thread_keyring(const char *key_desc) +{ + struct dm_crypt_key *key; + key_ref_t keyring_ref; + u64 addr; + + /* find the target keyring (which must be writable) */ + keyring_ref =3D + lookup_user_key(KEY_SPEC_USER_KEYRING, 0x01, KEY_NEED_WRITE); + if (IS_ERR(keyring_ref)) { + pr_alert("Failed to get keyring"); + return PTR_ERR(keyring_ref); + } + + addr =3D dm_crypt_keys_addr; + dm_crypt_keys_read((char *)&key_count, sizeof(key_count), &addr); + if (key_count < 0 || key_count > KEY_NUM_MAX) { + pr_info("Failed to the number of dm_crypt keys\n"); 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Peter Anvin" Subject: [PATCH v4 6/7] x86/crash: pass dm crypt keys to kdump kernel Date: Thu, 23 May 2024 13:04:47 +0800 Message-ID: <20240523050451.788754-7-coxu@redhat.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240523050451.788754-1-coxu@redhat.com> References: <20240523050451.788754-1-coxu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 1st kernel will build up the kernel command parameter dmcryptkeys as similar to elfcorehdr to pass the memory address of the stored info of dm crypt key to kdump kernel. Signed-off-by: Coiby Xu --- arch/x86/kernel/crash.c | 15 ++++++++++++++- arch/x86/kernel/kexec-bzimage64.c | 7 +++++++ 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index f06501445cd9..74b3844ae53c 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -266,6 +266,7 @@ static int memmap_exclude_ranges(struct kimage *image, = struct crash_mem *cmem, unsigned long long mend) { unsigned long start, end; + int r; =20 cmem->ranges[0].start =3D mstart; cmem->ranges[0].end =3D mend; @@ -274,7 +275,19 @@ static int memmap_exclude_ranges(struct kimage *image,= struct crash_mem *cmem, /* Exclude elf header region */ start =3D image->elf_load_addr; end =3D start + image->elf_headers_sz - 1; - return crash_exclude_mem_range(cmem, start, end); + r =3D crash_exclude_mem_range(cmem, start, end); + + if (r) + return r; + + /* Exclude dm crypt keys region */ + if (image->dm_crypt_keys_addr) { + start =3D image->dm_crypt_keys_addr; + end =3D start + image->dm_crypt_keys_sz - 1; + return crash_exclude_mem_range(cmem, start, end); + } + + return r; } =20 /* Prepare memory map for crash dump kernel */ diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzim= age64.c index 68530fad05f7..9c94428927bd 100644 --- a/arch/x86/kernel/kexec-bzimage64.c +++ b/arch/x86/kernel/kexec-bzimage64.c @@ -76,6 +76,10 @@ static int setup_cmdline(struct kimage *image, struct bo= ot_params *params, if (image->type =3D=3D KEXEC_TYPE_CRASH) { len =3D sprintf(cmdline_ptr, "elfcorehdr=3D0x%lx ", image->elf_load_addr); + + if (image->dm_crypt_keys_addr !=3D 0) + len +=3D sprintf(cmdline_ptr + len, + "dmcryptkeys=3D0x%lx ", image->dm_crypt_keys_addr); } memcpy(cmdline_ptr + len, cmdline, cmdline_len); cmdline_len +=3D len; @@ -441,6 +445,9 @@ static void *bzImage64_load(struct kimage *image, char = *kernel, ret =3D crash_load_segments(image); if (ret) return ERR_PTR(ret); + ret =3D crash_load_dm_crypt_keys(image); + if (ret) + pr_debug("Either no dm crypt key or error to retrieve the dm crypt key\= n"); 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Peter Anvin" Subject: [PATCH v4 7/7] x86/crash: make the page that stores the dm crypt keys inaccessible Date: Thu, 23 May 2024 13:04:48 +0800 Message-ID: <20240523050451.788754-8-coxu@redhat.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240523050451.788754-1-coxu@redhat.com> References: <20240523050451.788754-1-coxu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This adds an addition layer of protection for the saved copy of dm crypt key. Trying to access the saved copy will cause page fault. Suggested-by: Pingfan Liu Signed-off-by: Coiby Xu --- arch/x86/kernel/machine_kexec_64.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_k= exec_64.c index b180d8e497c3..fc0a80f4254e 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -545,13 +545,34 @@ static void kexec_mark_crashkres(bool protect) kexec_mark_range(control, crashk_res.end, protect); } =20 +static void kexec_mark_dm_crypt_keys(bool protect) +{ + unsigned long start_paddr, end_paddr; + unsigned int nr_pages; + + if (kexec_crash_image->dm_crypt_keys_addr) { + start_paddr =3D kexec_crash_image->dm_crypt_keys_addr; + end_paddr =3D start_paddr + kexec_crash_image->dm_crypt_keys_sz - 1; + nr_pages =3D (PAGE_ALIGN(end_paddr) - PAGE_ALIGN_DOWN(start_paddr))/PAGE= _SIZE; + if (protect) + set_memory_np((unsigned long)phys_to_virt(start_paddr), nr_pages); + else + __set_memory_prot( + (unsigned long)phys_to_virt(start_paddr), + nr_pages, + __pgprot(_PAGE_PRESENT | _PAGE_NX | _PAGE_RW)); + } +} + void arch_kexec_protect_crashkres(void) { kexec_mark_crashkres(true); + kexec_mark_dm_crypt_keys(true); } =20 void arch_kexec_unprotect_crashkres(void) { + kexec_mark_dm_crypt_keys(false); kexec_mark_crashkres(false); } #endif --=20 2.45.0