Commit 880a599e authored by Tom Gundersen's avatar Tom Gundersen Committed by Lennart Poettering
Browse files

cryptsetup: add keyfile-offset= support



This is useful if your keyfile is a block device, and you want to
use a specific part of it, such as an area between the MBR and the
first partition.

This feature is documented in the Arch wiki[0], and has been supported
by the Arch initscripts, so would be nice to get this into systemd.

This requires libcryptsetup >= 1.4.2 (released 12.4.2012).
Acked-by: default avatarPaul Menzel <paulepanter@users.sourceforge.net>

[0]:
<https://wiki.archlinux.org/index.php/System_Encryption_with_LUKS#
Storing_the_key_between_MBR_and_1st_partition>
parent 2be7287b
......@@ -333,7 +333,7 @@ AC_SUBST(AUDIT_LIBS)
have_libcryptsetup=no
AC_ARG_ENABLE(libcryptsetup, AS_HELP_STRING([--disable-libcryptsetup], [disable libcryptsetup tools]))
if test "x$enable_libcryptsetup" != "xno"; then
PKG_CHECK_MODULES(LIBCRYPTSETUP, [ libcryptsetup ],
PKG_CHECK_MODULES(LIBCRYPTSETUP, [ libcryptsetup >= 1.4.2 ],
[AC_DEFINE(HAVE_LIBCRYPTSETUP, 1, [Define if libcryptsetup is available]) have_libcryptsetup=yes], have_libcryptsetup=no)
if test "x$have_libcryptsetup" = xno -a "x$enable_libcryptsetup" = xyes; then
AC_MSG_ERROR([*** libcryptsetup support requested but libraries not found])
......
......@@ -130,6 +130,18 @@
</varlistentry>
<varlistentry>
<term><varname>keyfile-offset=</varname></term>
<listitem><para>Specifies the number
of bytes to skip at the start of
the keyfile; see
<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for possible values and the default
value of this option.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>hash=</varname></term>
......
......@@ -37,6 +37,7 @@
static const char *opt_type = NULL; /* LUKS1 or PLAIN */
static char *opt_cipher = NULL;
static unsigned opt_key_size = 0;
static unsigned opt_keyfile_offset = 0;
static char *opt_hash = NULL;
static unsigned opt_tries = 0;
static bool opt_readonly = false;
......@@ -79,6 +80,13 @@ static int parse_one_option(const char *option) {
return 0;
}
} else if (startswith(option, "keyfile-offset=")) {
if (safe_atou(option+15, &opt_keyfile_offset) < 0) {
log_error("keyfile-offset= parse failure, ignoring.");
return 0;
}
} else if (startswith(option, "hash=")) {
char *t;
......@@ -462,7 +470,8 @@ int main(int argc, char *argv[]) {
argv[3]);
if (key_file)
k = crypt_activate_by_keyfile(cd, argv[2], CRYPT_ANY_SLOT, key_file, keyfile_size, flags);
k = crypt_activate_by_keyfile_offset(cd, argv[2], CRYPT_ANY_SLOT, key_file, keyfile_size,
opt_keyfile_offset, flags);
else {
char **p;
......
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