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Tue, 09 Jan 2024 23:15:33 -0800 (PST) X-Received: by 2002:a17:90b:e0c:b0:28b:e09f:58c4 with SMTP id ge12-20020a17090b0e0c00b0028be09f58c4mr242170pjb.67.1704870933631; Tue, 09 Jan 2024 23:15:33 -0800 (PST) Received: from localhost ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id se3-20020a17090b518300b00274b035246esm434215pjb.1.2024.01.09.23.15.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jan 2024 23:15:33 -0800 (PST) From: Coiby Xu To: kexec@lists.infradead.org Cc: Ondrej Kozina , Milan Broz , Thomas Staudt , =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , Kairui Song , dm-devel@redhat.com, Jan Pazdziora , Pingfan Liu , Baoquan He , Dave Young , linux-kernel@vger.kernel.org, x86@kernel.org, Dave Hansen , Vitaly Kuznetsov , Vivek Goyal , Eric Biederman Subject: [PATCH v2 2/5] crash_dump: save the dm crypt key temporarily Date: Wed, 10 Jan 2024 15:15:17 +0800 Message-ID: <20240110071522.1308935-3-coxu@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240110071522.1308935-1-coxu@redhat.com> References: <20240110071522.1308935-1-coxu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1787686802783358578 X-GMAIL-MSGID: 1787686802783358578 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 --- 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 +#include + +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 (IS_ERR(key)) { + pr_debug("No such key %s", key_desc); + return PTR_ERR(key); + } + + ukp = user_key_payload_locked(key); + if (!ukp) + return -EKEYREVOKED; + + dm_crypt_key = kmalloc(ukp->datalen, GFP_KERNEL); + if (!dm_crypt_key) + return -ENOMEM; + memcpy(dm_crypt_key, ukp->data, ukp->datalen); + dm_crypt_key_size = ukp->datalen; + pr_debug("dm crypt key (size=%u): %8ph\n", dm_crypt_key_size, dm_crypt_key); + schedule_delayed_work(&wipe_dm_crypt_key_work, + round_jiffies_relative(wipe_key_delay * HZ)); + return 0; +} + +int crash_sysfs_dm_crypt_key_write(const char *key_desc, size_t count) +{ + if (!is_kdump_kernel()) + return crash_save_temp_dm_crypt_key(key_desc, count); + return -EINVAL; +} +EXPORT_SYMBOL(crash_sysfs_dm_crypt_key_write); + +int crash_pass_temp_dm_crypt_key(void **addr, unsigned long *sz) +{ + unsigned long dm_crypt_key_sz; + unsigned char *buf; + unsigned int *size_ptr; + + if (!dm_crypt_key) + return -EINVAL; + + dm_crypt_key_sz = sizeof(unsigned int) + dm_crypt_key_size * sizeof(u8); + + buf = vzalloc(dm_crypt_key_sz); + if (!buf) + return -ENOMEM; + + size_ptr = (unsigned int *)buf; + memcpy(size_ptr, &dm_crypt_key_size, sizeof(unsigned int)); + memcpy(size_ptr + 1, dm_crypt_key, dm_crypt_key_size * sizeof(u8)); + *addr = buf; + *sz = dm_crypt_key_sz; + wipe_dm_crypt_key(); + return 0; +} + +int crash_load_dm_crypt_key(struct kimage *image) +{ + int ret; + struct kexec_buf kbuf = { + .image = image, + .buf_min = 0, + .buf_max = ULONG_MAX, + .top_down = false, + .random = true, + }; + + image->dm_crypt_key_addr = 0; + ret = crash_pass_temp_dm_crypt_key(&kbuf.buffer, &kbuf.bufsz); + if (ret) + return ret; + + kbuf.memsz = kbuf.bufsz; + kbuf.buf_align = ELF_CORE_HEADER_ALIGN; + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; + ret = kexec_add_buffer(&kbuf); + if (ret) { + vfree((void *)kbuf.buffer); + return ret; + } + image->dm_crypt_key_addr = kbuf.mem; + image->dm_crypt_key_sz = kbuf.bufsz; + pr_debug("Loaded dm crypt key at 0x%lx bufsz=0x%lx memsz=0x%lx\n", + image->dm_crypt_key_addr, kbuf.bufsz, kbuf.bufsz); + + return ret; +} diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 1d4bc493b2f4..f3bb6bc6a604 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -165,16 +165,34 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj, } KERNEL_ATTR_RO(vmcoreinfo); +static ssize_t crash_dm_crypt_key_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return 0; +} + +static ssize_t crash_dm_crypt_key_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int ret; + + ret = crash_sysfs_dm_crypt_key_write(buf, count); + return ret < 0 ? ret : count; +} +KERNEL_ATTR_RW(crash_dm_crypt_key); + #ifdef CONFIG_CRASH_HOTPLUG static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) + struct kobj_attribute *attr, + char *buf) { unsigned int sz = crash_get_elfcorehdr_size(); return sysfs_emit(buf, "%u\n", sz); } KERNEL_ATTR_RO(crash_elfcorehdr_size); - #endif #endif /* CONFIG_CRASH_CORE */ @@ -267,6 +285,7 @@ static struct attribute * kernel_attrs[] = { #endif #ifdef CONFIG_CRASH_CORE &vmcoreinfo_attr.attr, + &crash_dm_crypt_key_attr.attr, #ifdef CONFIG_CRASH_HOTPLUG &crash_elfcorehdr_size_attr.attr, #endif