This is useful e.g. if the keyfile is a raw device, where only parts of it should be read. It is typically used whenever the keyfile-offset= option is specified. --- This patch is compile-tested only, and just meant for gathering feedback. Do you guys agree that this is necessary and sufficient to cover the use-case brought up by Heiko? Cheers, Tom man/crypttab.xml | 11 +++++++++++ src/cryptsetup/cryptsetup.c | 22 +++++++++++++++------- 2 files changed, 26 insertions(+), 7 deletions(-) diff --git a/man/crypttab.xml b/man/crypttab.xml index 2fa8e89..ba3f750 100644 --- a/man/crypttab.xml +++ b/man/crypttab.xml @@ -131,6 +131,17 @@ <varlistentry> + <term><varname>keyfile-size=</varname></term> + + <listitem><para>Specifies the maximum number + of bytes to read from 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>keyfile-offset=</varname></term> <listitem><para>Specifies the number diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c index cc30e50..1035ac4 100644 --- a/src/cryptsetup/cryptsetup.c +++ b/src/cryptsetup/cryptsetup.c @@ -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_size = 0; static unsigned opt_keyfile_offset = 0; static char *opt_hash = NULL; static unsigned opt_tries = 0; @@ -80,6 +81,13 @@ static int parse_one_option(const char *option) { return 0; } + } else if (startswith(option, "keyfile-size=")) { + + if (safe_atou(option+13, &opt_keyfile_offset) < 0) { + log_error("keyfile-size= parse failure, ignoring."); + return 0; + } + } else if (startswith(option, "keyfile-offset=")) { if (safe_atou(option+15, &opt_keyfile_offset) < 0) { @@ -238,7 +246,6 @@ int main(int argc, char *argv[]) { char **passwords = NULL, *truncated_cipher = NULL; const char *cipher = NULL, *cipher_mode = NULL, *hash = NULL, *name = NULL; char *description = NULL, *name_buffer = NULL, *mount_point = NULL; - unsigned keyfile_size = 0; if (argc <= 1) { help(); @@ -437,6 +444,11 @@ int main(int argc, char *argv[]) { zero(params); params.hash = hash; + /* for CRYPT_PLAIN limit reads + * from keyfile to key length, and + * ignore keyfile-size */ + opt_keyfile_size = opt_key_size / 8; + /* In contrast to what the name * crypt_setup() might suggest this * doesn't actually format anything, @@ -448,14 +460,10 @@ int main(int argc, char *argv[]) { cipher_mode, NULL, NULL, - opt_key_size / 8, + opt_keyfile_size, ¶ms); pass_volume_key = streq(hash, "plain"); - - /* for CRYPT_PLAIN limit reads - * from keyfile to key length */ - keyfile_size = opt_key_size / 8; } if (k < 0) { @@ -470,7 +478,7 @@ int main(int argc, char *argv[]) { argv[3]); if (key_file) - k = crypt_activate_by_keyfile_offset(cd, argv[2], CRYPT_ANY_SLOT, key_file, keyfile_size, + k = crypt_activate_by_keyfile_offset(cd, argv[2], CRYPT_ANY_SLOT, key_file, opt_keyfile_size, opt_keyfile_offset, flags); else { char **p; -- 1.7.11.3