From 8cf3ca80680b43015971cbbf4625517ae859d50c Mon Sep 17 00:00:00 2001 From: Jan Janssen Date: Sat, 13 Jul 2013 13:19:38 +0200 Subject: [PATCH] cryptsetup: Add tcrypt support Tcrypt uses a different approach to passphrases/key files. The passphrase and all key files are incorporated into the "password" to open the volume. So, the idea of slots that provide a way to open the volume with different passphrases/key files that are independent from each other like with LUKS does not apply. Therefore, we use the key file from /etc/crypttab as the source for the passphrase. The actual key files that are combined with the passphrase into a password are provided as a new option in /etc/crypttab and can be given multiple times if more than one key file is used by a volume. --- configure.ac | 2 +- man/crypttab.xml | 300 ++++++++++++++++++++++-------------- src/cryptsetup/cryptsetup.c | 79 +++++++++- 3 files changed, 258 insertions(+), 123 deletions(-) diff --git a/configure.ac b/configure.ac index afbe8e904..6f5fee5fc 100644 --- a/configure.ac +++ b/configure.ac @@ -576,7 +576,7 @@ AC_SUBST(AUDIT_LIBS) have_libcryptsetup=no AC_ARG_ENABLE(libcryptsetup, AS_HELP_STRING([--disable-libcryptsetup], [disable libcryptsetup tools])) if test "x$enable_libcryptsetup" != "xno"; then - PKG_CHECK_MODULES(LIBCRYPTSETUP, [ libcryptsetup >= 1.4.2 ], + PKG_CHECK_MODULES(LIBCRYPTSETUP, [ libcryptsetup >= 1.6.0 ], [AC_DEFINE(HAVE_LIBCRYPTSETUP, 1, [Define if libcryptsetup is available]) have_libcryptsetup=yes], have_libcryptsetup=no) if test "x$have_libcryptsetup" = xno -a "x$enable_libcryptsetup" = xyes; then AC_MSG_ERROR([*** libcryptsetup support requested but libraries not found]) diff --git a/man/crypttab.xml b/man/crypttab.xml index e52b7e601..298f39e0e 100644 --- a/man/crypttab.xml +++ b/man/crypttab.xml @@ -75,23 +75,29 @@ fields are mandatory, the remaining two are optional. + Setting up encrypted block devices using this file + supports three encryption modes: LUKS, TrueCrypt and plain. + See cryptsetup8 + for more information about each mode. When no mode is specified + in the options field and the block device contains a LUKS + signature, it is opened as a LUKS device; otherwise, it is + assumed to be in raw dm-crypt (plain mode) format. + The first field contains the name of the resulting encrypted block device; the device is set up within /dev/mapper/. The second field contains a path to the - underlying block device, or a specification of a block + underlying block device or file, or a specification of a block device via UUID= followed by the - UUID. If the block device contains a LUKS signature, - it is opened as a LUKS encrypted partition; otherwise, - it is assumed to be a raw dm-crypt partition. + UUID. The third field specifies the encryption password. If the field is not present or the password - is set to none, the password has to be manually - entered during system boot. Otherwise, the field is - interpreted as a path to a file containing the - encryption password. For swap encryption, + is set to none or -, + the password has to be manually entered during system boot. + Otherwise, the field is interpreted as a absolute path to + a file containing the encryption password. For swap encryption, /dev/urandom or the hardware device /dev/hw_random can be used as the password file; using @@ -104,181 +110,237 @@ options are recognized: + + + allow-discards + + Allow discard requests to be + passed through the encrypted block device. This + improves performance on SSD storage but has + security implications. + + cipher= - Specifies the cipher - to use; see + Specifies the cipher to use. See cryptsetup8 - for possible values and the default - value of this option. A cipher with - unpredictable IV values, such as - aes-cbc-essiv:sha256, - is recommended. + for possible values and the default value of + this option. A cipher with unpredictable IV + values, such as aes-cbc-essiv:sha256, + is recommended. - - size= + hash= - Specifies the key size - in bits; see + Specifies the hash to use for + password hashing. See cryptsetup8 - for possible values and the default - value of this - option. + for possible values and the default value of + this option. + + keyfile-offset= + + Specifies the number of bytes to + skip at the start of the key file. See + cryptsetup8 + for possible values and the default value of + this option. + keyfile-size= Specifies the maximum number - of bytes to read from the keyfile; see + of bytes to read from the key file. See cryptsetup8 - for possible values and the default - value of this option. This option is ignored - in plain encryption mode, as the keyfile-size is then given by the key size. + for possible values and the default value of + this option. This option is ignored in plain + encryption mode, as the key file size is then + given by the key size. - - keyfile-offset= + luks - Specifies the number - of bytes to skip at the start of - the keyfile; see - cryptsetup8 - for possible values and the default - value of this option. + Force LUKS mode. When this mode + is used the following options are ignored since + they are provided by the LUKS header on the + device: cipher=, + hash=, + size=. - - hash= + noauto - Specifies the hash to - use for password hashing; see - cryptsetup8 for possible values and - the default value of this - option. + This device will not be + automatically unlocked on boot. - tries= + nofail - Specifies the maximum - number of times the user is queried - for a password. + The system will not wait for the + device to show up and be unlocked at boot, and + not fail the boot if it does not show up. - verify + plain - If the encryption - password is read from console, it has - to be entered twice (to prevent - typos). + Force plain encryption mode. read-onlyreadonly - Set up the encrypted - block device in read-only - mode. + Set up the encrypted block + device in read-only mode. - allow-discards + size= - Allow discard requests - to be passed through the encrypted - block device. This improves - performance on SSD storage but has - security - implications. + Specifies the key size + in bits. See + cryptsetup8 + for possible values and the default value of + this option. - luks + swap - Force LUKS mode. + The encrypted block device will + be used as a swap device, and will be formatted + accordingly after setting up the encrypted + block device, with + mkswap8. + This option implies plain. + + WARNING: Using the swap + option will destroy the contents of the named + partition during every boot, so make sure the + underlying block device is specified correctly. - plain + tcrypt + + Use TrueCrypt encryption mode. + When this mode is used the following options are + ignored since they are provided by the TrueCrypt + header on the device or do not apply: + cipher=, + hash=, + keyfile-offset=, + keyfile-size=, + size=. + + When this mode is used, the passphrase is + read from the key file given in the third field. + Only the first line of this file is read, + excluding the new line character. + + Note that the TrueCrypt format uses both + passphrase and key files to derive a password + for the volume. Therefore, the passphrase and + all key files need to be provided. Use + tcrypt-keyfile= to provide + the absolute path to all key files. When using + an empty passphrase in combination with one or + more key files, use /dev/null + as the password file in the third field. + - Force plain encryption - mode. + + tcrypt-hidden + + Use the hidden TrueCrypt volume. + This implies tcrypt. + + This will map the hidden volume that is + inside of the volume provided in the second + field. Please note that there is no protection + for the hidden volume if the outer volume is + mounted instead. See + cryptsetup8 + for more information on this limitation. - timeout= + tcrypt-keyfile= + + Specifies the absolute path to a + key file to use for a TrueCrypt volume. This + implies tcrypt and can be + used more than once to provide several key + files. - Specify the timeout - for querying for a password. If no - unit is specified seconds is used. - Supported units are s, ms, us, min, h, - d. A timeout of 0 waits indefinitely - (which is the - default). + See the entry for tcrypt + on the behavior of the passphrase and key files + when using TrueCrypt encryption mode. - noauto + tcrypt-system + + Use TrueCrypt in system + encryption mode. This implies + tcrypt. + + Please note that when using this mode, the + whole device needs to be given in the second + field instead of the partition. For example: if + /dev/sda2 is the system + encrypted TrueCrypt patition, /dev/sda + has to be given. + + + + timeout= - This device will not - be automatically unlocked on - boot. + Specifies the timeout for + querying for a password. If no unit is + specified, seconds is used. Supported units are + s, ms, us, min, h, d. A timeout of 0 waits + indefinitely (which is the default). - nofail + tmp + + The encrypted block device will + be prepared for using it as /tmp; + it will be formatted using + mke2fs8. + This option implies plain. - The system will not - wait for the device to show up and be - unlocked at boot, and not fail the - boot if it does not show - up. + WARNING: Using the tmp + option will destroy the contents of the named + partition during every boot, so make sure the + underlying block device is specified correctly. - swap + tries= - The encrypted block - device will be used as a swap - partition, and will be formatted as a - swap partition after setting up the - encrypted block device, with - mkswap8. - - WARNING: Using the - swap option will - destroy the contents of the named - partition during every boot, so make - sure the underlying block device is - specified - correctly. + Specifies the maximum number of + times the user is queried for a password. - tmp + verify - The encrypted block - device will be prepared for using it - as /tmp - partition: it will be formatted using - mke2fs8. - - WARNING: Using the - tmp option will - destroy the contents of the named - partition during every boot, so make - sure the underlying block device is - specified - correctly. + If the encryption password is + read from console, it has to be entered twice to + prevent typos. + At early boot and when the system manager @@ -291,12 +353,14 @@ Example /etc/crypttab example - Set up two encrypted block devices with - LUKS: one normal one for storage, and another - one for usage as swap device. - - luks-2505567a-9e27-4efe-a4d5-15ad146c258b UUID=2505567a-9e27-4efe-a4d5-15ad146c258b - timeout=0 -swap /dev/sda7 /dev/urandom swap + Set up four encrypted block devices. One using + LUKS for normal storage, another one for usage as a swap + device and two TrueCrypt volumes. + + luks UUID=2505567a-9e27-4efe-a4d5-15ad146c258b +swap /dev/sda7 /dev/urandom swap +truecrypt /dev/sda2 /etc/container_password tcrypt +hidden /mnt/tc_hidden /null tcrypt-hidden,tcrypt-keyfile=/etc/keyfile diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c index e84ebba68..3a2cfe459 100644 --- a/src/cryptsetup/cryptsetup.c +++ b/src/cryptsetup/cryptsetup.c @@ -27,6 +27,7 @@ #include #include +#include "fileio.h" #include "log.h" #include "util.h" #include "path-util.h" @@ -34,7 +35,7 @@ #include "ask-password-api.h" #include "def.h" -static const char *opt_type = NULL; /* LUKS1 or PLAIN */ +static const char *opt_type = NULL; /* CRYPT_LUKS1, CRYPT_TCRYPT or CRYPT_PLAIN */ static char *opt_cipher = NULL; static unsigned opt_key_size = 0; static unsigned opt_keyfile_size = 0; @@ -44,6 +45,9 @@ static unsigned opt_tries = 0; static bool opt_readonly = false; static bool opt_verify = false; static bool opt_discards = false; +static bool opt_tcrypt_hidden = false; +static bool opt_tcrypt_system = false; +static char **opt_tcrypt_keyfiles = NULL; static usec_t opt_timeout = 0; /* Options Debian's crypttab knows we don't: @@ -82,6 +86,14 @@ static int parse_one_option(const char *option) { return 0; } + } else if (startswith(option, "tcrypt-keyfile=")) { + + opt_type = CRYPT_TCRYPT; + if (path_is_absolute(option+15)) + opt_tcrypt_keyfiles = strv_append(opt_tcrypt_keyfiles, strdup(option+15)); + else + log_error("Key file path '%s' is not absolute. Ignoring.", option+15); + } else if (startswith(option, "keyfile-size=")) { if (safe_atou(option+13, &opt_keyfile_size) < 0) { @@ -121,7 +133,15 @@ static int parse_one_option(const char *option) { opt_discards = true; else if (streq(option, "luks")) opt_type = CRYPT_LUKS1; - else if (streq(option, "plain") || + else if (streq(option, "tcrypt")) + opt_type = CRYPT_TCRYPT; + else if (streq(option, "tcrypt-hidden")) { + opt_type = CRYPT_TCRYPT; + opt_tcrypt_hidden = true; + } else if (streq(option, "tcrypt-system")) { + opt_type = CRYPT_TCRYPT; + opt_tcrypt_system = true; + } else if (streq(option, "plain") || streq(option, "swap") || streq(option, "tmp")) opt_type = CRYPT_PLAIN; @@ -301,6 +321,53 @@ static int get_password(const char *name, usec_t until, bool accept_cached, char return 0; } +static int attach_tcrypt(struct crypt_device *cd, + const char *name, + const char *key_file, + char **passwords, + uint32_t flags) { + int r = 0; + _cleanup_free_ char *passphrase = NULL; + struct crypt_params_tcrypt params = { + .flags = CRYPT_TCRYPT_LEGACY_MODES, + .keyfiles = (const char **)opt_tcrypt_keyfiles, + .keyfiles_count = strv_length(opt_tcrypt_keyfiles) + }; + + assert(cd); + assert(name); + assert(key_file || passwords); + + if (opt_tcrypt_hidden) + params.flags |= CRYPT_TCRYPT_HIDDEN_HEADER; + + if (opt_tcrypt_system) + params.flags |= CRYPT_TCRYPT_SYSTEM_HEADER; + + if (key_file) { + r = read_one_line_file(key_file, &passphrase); + if (r < 0) { + log_error("Failed to read password file '%s': %s", key_file, strerror(-r)); + return -EAGAIN; + } + + params.passphrase = passphrase; + } else + params.passphrase = passwords[0]; + params.passphrase_size = strlen(params.passphrase); + + r = crypt_load(cd, CRYPT_TCRYPT, ¶ms); + if (r < 0) { + if (key_file && r == -EPERM) { + log_error("Failed to activate using password file '%s'.", key_file); + return -EAGAIN; + } + return r; + } + + return crypt_activate_by_volume_key(cd, name, NULL, 0, flags);; +} + static int attach_luks_or_plain(struct crypt_device *cd, const char *name, const char *key_file, @@ -450,7 +517,7 @@ int main(int argc, char *argv[]) { !streq(argv[4], "none")) { if (!path_is_absolute(argv[4])) - log_error("Password file path %s is not absolute. Ignoring.", argv[4]); + log_error("Password file path '%s' is not absolute. Ignoring.", argv[4]); else key_file = argv[4]; } @@ -532,7 +599,10 @@ int main(int argc, char *argv[]) { goto finish; } - k = attach_luks_or_plain(cd, argv[2], key_file, passwords, flags); + if (streq_ptr(opt_type, CRYPT_TCRYPT)) + k = attach_tcrypt(cd, argv[2], key_file, passwords, flags); + else + k = attach_luks_or_plain(cd, argv[2], key_file, passwords, flags); if (k >= 0) break; else if (k == -EAGAIN) { @@ -583,6 +653,7 @@ finish: free(opt_cipher); free(opt_hash); + strv_free(opt_tcrypt_keyfiles); return r; } -- 2.30.2