-
Steve McIntyre authoredSteve McIntyre authored
osdep-devmapper-getroot-set-up-cheated-luks2-cryptodisk-mount-from-dm-parameters.patch 6.30 KiB
From: Josselin Poiret <dev@jpoiret.xyz>
Date: Thu, 12 Jan 2023 17:05:09 -0600
Subject: osdep/devmapper/getroot: Set up cheated LUKS2 cryptodisk mount from
DM parameters
Origin: https://git.savannah.gnu.org/cgit/grub.git/commit/?id=aa5172a55cfabdd0bed3161ad44fc228b9d019f7
Bug-Debian: https://bugs.debian.org/1028301
This lets a LUKS2 cryptodisk have its cipher and hash filled out,
otherwise they wouldn't be initialized if cheat mounted.
Signed-off-by: Josselin Poiret <dev@jpoiret.xyz>
Tested-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/osdep/devmapper/getroot.c | 107 +++++++++++++++++++++++++++++++++++-
1 file changed, 106 insertions(+), 1 deletion(-)
diff --git a/grub-core/osdep/devmapper/getroot.c b/grub-core/osdep/devmapper/getroot.c
index 2bf4264..cc3f7da 100644
--- a/grub-core/osdep/devmapper/getroot.c
+++ b/grub-core/osdep/devmapper/getroot.c
@@ -51,6 +51,8 @@
#include <grub/emu/misc.h>
#include <grub/emu/hostdisk.h>
+#include <grub/cryptodisk.h>
+
static int
grub_util_open_dm (const char *os_dev, struct dm_tree **tree,
struct dm_tree_node **node)
@@ -186,7 +188,6 @@ grub_util_pull_devmapper (const char *os_dev)
&& lastsubdev)
{
char *grdev = grub_util_get_grub_dev (lastsubdev);
- dm_tree_free (tree);
if (grdev)
{
grub_err_t err;
@@ -194,7 +195,111 @@ grub_util_pull_devmapper (const char *os_dev)
if (err)
grub_util_error (_("can't mount encrypted volume `%s': %s"),
lastsubdev, grub_errmsg);
+ if (strncmp (uuid, "CRYPT-LUKS2-", sizeof ("CRYPT-LUKS2-") - 1) == 0)
+ {
+ /*
+ * Set LUKS2 cipher from dm parameters, since it is not
+ * possible to determine the correct one without
+ * unlocking, as there might be multiple segments.
+ */
+ grub_disk_t source;
+ grub_cryptodisk_t cryptodisk;
+ grub_uint64_t start, length;
+ char *target_type;
+ char *params;
+ const char *name;
+ char *cipher, *cipher_mode;
+ struct dm_task *dmt;
+ char *seek_head, *c;
+ unsigned int remaining;
+
+ source = grub_disk_open (grdev);
+ if (! source)
+ grub_util_error (_("cannot open grub disk `%s'"), grdev);
+ cryptodisk = grub_cryptodisk_get_by_source_disk (source);
+ if (! cryptodisk)
+ grub_util_error (_("cannot get cryptodisk from source disk `%s'"), grdev);
+ grub_disk_close (source);
+
+ /*+ * The following function always returns a non-NULL pointer,
+ * but the string may be empty if the relevant info is not present.
+ */
+ name = dm_tree_node_get_name (node);
+ if (*name == '\0')
+ grub_util_error (_("cannot get dm node name for grub dev `%s'"), grdev);
+
+ grub_util_info ("populating parameters of cryptomount `%s' from DM device `%s'",
+ uuid, name);
+
+ dmt = dm_task_create (DM_DEVICE_TABLE);
+ if (dmt == NULL)
+ grub_util_error (_("can't create dm task DM_DEVICE_TABLE"));
+ if (dm_task_set_name (dmt, name) == 0)
+ grub_util_error (_("can't set dm task name to `%s'"), name);
+ if (dm_task_run (dmt) == 0)
+ grub_util_error (_("can't run dm task for `%s'"), name);
+ /*
+ * dm_get_next_target() doesn't have any error modes, everything has
+ * been handled by dm_task_run().
+ */
+ dm_get_next_target (dmt, NULL, &start, &length,
+ &target_type, ¶ms);
+ if (strncmp (target_type, "crypt", sizeof ("crypt")) != 0)
+ grub_util_error (_("dm target of type `%s' is not `crypt'"), target_type);
+
+ /*
+ * The dm target parameters for dm-crypt are
+ * <cipher> <key> <iv_offset> <device path> <offset> [<#opt_params> <opt_param1> ...]
+ */
+ c = params;
+ remaining = grub_strlen (c);
+
+ /* First, get the cipher name from the cipher. */
+ seek_head = grub_memchr (c, '-', remaining);
+ if (seek_head == NULL)
+ grub_util_error (_("can't get cipher from dm-crypt parameters `%s'"),
+ params);
+ cipher = grub_strndup (c, seek_head - c);
+ if (cipher == NULL)
+ grub_util_error (_("could not strndup cipher of length `%u'"), seek_head - c);
+ remaining -= seek_head - c + 1;
+ c = seek_head + 1;
+
+ /* Now, the cipher mode. */
+ seek_head = grub_memchr (c, ' ', remaining);
+ if (seek_head == NULL)
+ grub_util_error (_("can't get cipher mode from dm-crypt parameters `%s'"),
+ params);
+ cipher_mode = grub_strndup (c, seek_head - c);
+ if (cipher_mode == NULL)
+ grub_util_error (_("could not strndup cipher_mode of length `%u'"), seek_head - c);
+
+ remaining -= seek_head - c + 1;
+ c = seek_head + 1;
+
+ err = grub_cryptodisk_setcipher (cryptodisk, cipher, cipher_mode);
+ if (err)
+ grub_util_error (_("can't set cipher of cryptodisk `%s' to `%s' with mode `%s'"),
+ uuid, cipher, cipher_mode);
+
+ grub_free (cipher);
+ grub_free (cipher_mode);
+
+ /*
+ * This is the only hash usable by PBKDF2, and we don't
+ * have Argon2 support yet, so set it by default,
+ * otherwise grub-probe would miss the required
+ * abstraction.
+ */+ cryptodisk->hash = grub_crypto_lookup_md_by_name ("sha256");
+ if (cryptodisk->hash == NULL)
+ grub_util_error (_("can't lookup hash sha256 by name"));
+
+ dm_task_destroy (dmt);
+ }
}
+ dm_tree_free (tree);
grub_free (grdev);
}
else
--
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