cryptsetup: support header= option

https://bugs.freedesktop.org/show_bug.cgi?id=66396

2 files changed, 53 insertions, 3 deletions

diff --git a/man/crypttab.xml b/man/crypttab.xml
index 42caf3430..737b23233 100644
--- a/man/crypttab.xml
+++ b/man/crypttab.xml
@@ -142,6 +142,18 @@
                         </varlistentry>
 
                         <varlistentry>
+                                <term><option>header=</option></term>
+
+                                <listitem><para>Use a detached (separated)
+                                metadata device or file where the LUKS header
+                                is stored. This option is only relevant for
+                                LUKS devices. See
+                                <citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                                for possible values and the default value of
+                                this option.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
                                 <term><option>keyfile-offset=</option></term>
 
                                 <listitem><para>Specifies the number of bytes to
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 21b1260f1..15dea7b65 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -43,6 +43,7 @@ static int arg_key_slot = CRYPT_ANY_SLOT;
 static unsigned arg_keyfile_size = 0;
 static unsigned arg_keyfile_offset = 0;
 static char *arg_hash = NULL;
+static char *arg_header = NULL;
 static unsigned arg_tries = 3;
 static bool arg_readonly = false;
 static bool arg_verify = false;
@@ -136,6 +137,23 @@ static int parse_one_option(const char *option) {
                 free(arg_hash);
                 arg_hash = t;
 
+        } else if (startswith(option, "header=")) {
+                arg_type = CRYPT_LUKS1;
+
+                if (!path_is_absolute(option+7)) {
+                        log_error("Header path '%s' is not absolute, refusing.", option+7);
+                        return -EINVAL;
+                }
+
+                if (arg_header) {
+                        log_error("Duplicate header= options, refusing.");
+                        return -EINVAL;
+                }
+
+                arg_header = strdup(option+7);
+                if (!arg_header)
+                        return log_oom();
+
         } else if (startswith(option, "tries=")) {
 
                 if (safe_atou(option+6, &arg_tries) < 0) {
@@ -375,6 +393,7 @@ static int attach_tcrypt(struct crypt_device *cd,
 static int attach_luks_or_plain(struct crypt_device *cd,
                                 const char *name,
                                 const char *key_file,
+                                const char *data_device,
                                 char **passwords,
                                 uint32_t flags) {
         int r = 0;
@@ -384,8 +403,16 @@ static int attach_luks_or_plain(struct crypt_device *cd,
         assert(name);
         assert(key_file || passwords);
 
-        if (!arg_type || streq(arg_type, CRYPT_LUKS1))
+        if (!arg_type || streq(arg_type, CRYPT_LUKS1)) {
                 r = crypt_load(cd, CRYPT_LUKS1, NULL);
+                if (r < 0) {
+                        log_error("crypt_load() failed on device %s.\n", crypt_get_device_name(cd));
+                        return r;
+                }
+
+                if (data_device)
+                        r = crypt_set_data_device(cd, data_device);
+        }
 
         if ((!arg_type && r < 0) || streq_ptr(arg_type, CRYPT_PLAIN)) {
                 struct crypt_params_plain params = {};
@@ -559,7 +586,12 @@ int main(int argc, char *argv[]) {
                 }
                 name = name_buffer ? name_buffer : argv[2];
 
-                k = crypt_init(&cd, argv[3]);
+                if (arg_header) {
+                        log_debug("LUKS header: %s", arg_header);
+                        k = crypt_init(&cd, arg_header);
+                } else
+                        k = crypt_init(&cd, argv[3]);
+
                 if (k) {
                         log_error_errno(k, "crypt_init() failed: %m");
                         goto finish;
@@ -610,7 +642,12 @@ int main(int argc, char *argv[]) {
                         if (streq_ptr(arg_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);
+                                k = attach_luks_or_plain(cd,
+                                                         argv[2],
+                                                         key_file,
+                                                         arg_header ? argv[3] : NULL,
+                                                         passwords,
+                                                         flags);
                         if (k >= 0)
                                 break;
                         else if (k == -EAGAIN) {
@@ -661,6 +698,7 @@ finish:
 
         free(arg_cipher);
         free(arg_hash);
+        free(arg_header);
         strv_free(arg_tcrypt_keyfiles);
 
         return r;