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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Crash kernel will retrieve the dm crypt volume key based on the dmcryptkey command line parameter. When user space writes the key description to /sys/kernel/crash_dm_crypt_key, the crash kernel will save the encryption key 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_dump.h | 2 + kernel/crash_dump_dm_crypt.c | 115 ++++++++++++++++++++++++++++++++++- 2 files changed, 116 insertions(+), 1 deletion(-) diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h index acc55626afdc..b44adc3962da 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; +extern unsigned long long luks_volume_key_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/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 3a0b0b773598..755017fa5c1b 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -1,7 +1,82 @@ // SPDX-License-Identifier: GPL-2.0-only +#include +#include #include #include +unsigned long long dm_crypt_key_addr; +EXPORT_SYMBOL_GPL(dm_crypt_key_addr); + +static int __init setup_dmcryptkey(char *arg) +{ + char *end; + + if (!arg) + return -EINVAL; + dm_crypt_key_addr = memparse(arg, &end); + if (end > arg) + return 0; + + dm_crypt_key_addr = 0; + return -EINVAL; +} + +early_param("dmcryptkey", setup_dmcryptkey); + +/* + * Architectures may override this function to read dm crypt key + */ +ssize_t __weak dm_crypt_key_read(char *buf, size_t count, u64 *ppos) +{ + struct kvec kvec = { .iov_base = buf, .iov_len = count }; + struct iov_iter iter; + + iov_iter_kvec(&iter, READ, &kvec, 1, count); + return read_from_oldmem(&iter, count, ppos, false); +} + +static int retrive_kdump_dm_crypt_key(u8 *buffer, unsigned int *sz) +{ + unsigned int key_size; + size_t dm_crypt_keybuf_sz; + unsigned int *size_ptr; + char *dm_crypt_keybuf; + u64 addr; + int r; + + if (dm_crypt_key_addr == 0) { + pr_debug("dm crypt key memory address inaccessible"); + return -EINVAL; + } + + addr = dm_crypt_key_addr; + + /* Read dm crypt key size */ + r = dm_crypt_key_read((char *)&key_size, sizeof(unsigned int), &addr); + + if (r < 0) + return r; + + pr_debug("Retrieve dm crypt key: size=%u\n", key_size); + /* Read in dm cryptrkey */ + dm_crypt_keybuf_sz = sizeof(unsigned int) + key_size * sizeof(u8); + dm_crypt_keybuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + get_order(dm_crypt_keybuf_sz)); + if (!dm_crypt_keybuf) + return -ENOMEM; + + addr = dm_crypt_key_addr; + r = dm_crypt_key_read((char *)dm_crypt_keybuf, dm_crypt_keybuf_sz, &addr); + + if (r < 0) + return r; + size_ptr = (unsigned int *)dm_crypt_keybuf; + memcpy(buffer, size_ptr + 1, key_size * sizeof(u8)); + pr_debug("Retrieve dm crypt key (size=%u): %48ph...\n", key_size, buffer); + *sz = key_size; + return 0; +} + static u8 *dm_crypt_key; static unsigned int dm_crypt_key_size; @@ -23,6 +98,43 @@ 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 retore_dm_crypt_key_to_thread_keyring(const char *key_desc) +{ + key_ref_t keyring_ref, key_ref; + int ret; + + /* find the target keyring (which must be writable) */ + keyring_ref = 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); + } + + dm_crypt_key = kmalloc(128, GFP_KERNEL); + ret = retrive_kdump_dm_crypt_key(dm_crypt_key, &dm_crypt_key_size); + if (ret) { + kfree(dm_crypt_key); + return ret; + } + + /* create or update the requested key and add it to the target keyring */ + key_ref = key_create_or_update(keyring_ref, "user", key_desc, + dm_crypt_key, dm_crypt_key_size, + KEY_USR_ALL, KEY_ALLOC_IN_QUOTA); + + if (!IS_ERR(key_ref)) { + ret = key_ref_to_ptr(key_ref)->serial; + key_ref_put(key_ref); + pr_alert("Success adding key %s", key_desc); + } else { + ret = PTR_ERR(key_ref); + pr_alert("Error when adding key"); + } + + key_ref_put(keyring_ref); + return ret; +} + static int crash_save_temp_dm_crypt_key(const char *key_desc, size_t count) { const struct user_key_payload *ukp; @@ -60,7 +172,8 @@ 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; + else + return retore_dm_crypt_key_to_thread_keyring(key_desc); } EXPORT_SYMBOL(crash_sysfs_dm_crypt_key_write); -- 2.43.0 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec