Give the user a chance to re-enter their cryptodisk passphrase after a typo,
rather than immediately failing (and likely dumping them into a grub shell).
By default, we allow 3 tries before giving up. A value in the
cryptodisk_passphrase_tries environment variable will override this default.
The user can give up early by entering an empty passphrase, just as they
could before this patch.
Signed-off-by: Forest <fores...@nom.one>
---
docs/grub.texi | 9 +++++
grub-core/disk/cryptodisk.c | 74 +++++++++++++++++++++++++++++--------
2 files changed, 67 insertions(+), 16 deletions(-)
diff --git a/docs/grub.texi b/docs/grub.texi
index a225f9a88..6ac603a32 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -3277,6 +3277,7 @@ These variables have special meaning to GRUB.
* color_normal::
* config_directory::
* config_file::
+* cryptodisk_passphrase_tries::
* debug::
* default::
* fallback::
@@ -3441,6 +3442,14 @@ processed by commands @command{configfile}
(@pxref{configfile}) or @command{norm
(@pxref{normal}). It is restored to the previous value when command completes.
+@node cryptodisk_passphrase_tries
+@subsection cryptodisk_passphrase_tries
+
+When prompting the user for a cryptodisk passphrase, allow this many attempts
+before giving up. The default is @samp{3}. (The user can give up early by
+entering an empty passphrase.)
+
+
@node debug
@subsection debug
diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 2246af51b..4fa7dc58d 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -17,6 +17,7 @@
*/
#include <grub/cryptodisk.h>
+#include <grub/env.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/dl.h>
@@ -1063,6 +1064,8 @@ grub_cryptodisk_scan_device_real (const char *name,
grub_cryptodisk_dev_t cr;
struct cryptodisk_read_hook_ctx read_hook_data = {0};
int askpass = 0;
+ unsigned long tries = 3;
+ const char *tries_env;
char *part = NULL;
dev = grub_cryptodisk_get_by_source_disk (source);
@@ -1114,32 +1117,71 @@ grub_cryptodisk_scan_device_real (const char *name,
if (!dev)
continue;
- if (!cargs->key_len)
+ if (cargs->key_len)
+ {
+ ret = cr->recover_key (source, dev, cargs);
+ if (ret != GRUB_ERR_NONE)
+ goto error;
+ }
+ else
{
/* Get the passphrase from the user, if no key data. */
askpass = 1;
- part = grub_partition_get_name (source->partition);
- grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
- source->partition != NULL ? "," : "",
- part != NULL ? part : N_("UNKNOWN"),
- dev->uuid);
- grub_free (part);
-
cargs->key_data = grub_malloc (GRUB_CRYPTODISK_MAX_PASSPHRASE);
if (cargs->key_data == NULL)
goto error_no_close;
- if (!grub_password_get ((char *) cargs->key_data,
GRUB_CRYPTODISK_MAX_PASSPHRASE))
+ tries_env = grub_env_get ("cryptodisk_passphrase_tries");
+ if (tries_env != NULL && tries_env[0] != '\0')
{
- grub_error (GRUB_ERR_BAD_ARGUMENT, "passphrase not supplied");
- goto error;
+ const char *p = NULL;
+ tries = grub_strtoul (tries_env, &p, 0);
+ if (*p != '\0')
+ {
+ /* Account for grub_strtoul() ignoring trailing text. */
+ grub_err_t err = grub_errno;
+ if (p > tries_env && tries != ~0UL)
+ err = GRUB_ERR_BAD_NUMBER;
+
+ grub_error (err,
+ N_("non-numeric or invalid value for
cryptodisk_passphrase_tries: `%s'"),
+ tries_env);
+ goto error;
+ }
}
- cargs->key_len = grub_strlen ((char *) cargs->key_data);
- }
- ret = cr->recover_key (source, dev, cargs);
- if (ret != GRUB_ERR_NONE)
- goto error;
+ for (; tries > 0; tries--)
+ {
+ part = grub_partition_get_name (source->partition);
+ grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "),
source->name,
+ source->partition != NULL ? "," : "",
+ part != NULL ? part : N_("UNKNOWN"),
+ dev->uuid);
+ grub_free (part);
+
+ if (!grub_password_get ((char *) cargs->key_data,
GRUB_CRYPTODISK_MAX_PASSPHRASE))
+ {
+ grub_error (GRUB_ERR_BAD_ARGUMENT, "passphrase not supplied");
+ goto error;
+ }
+ cargs->key_len = grub_strlen ((char *) cargs->key_data);
+
+ ret = cr->recover_key (source, dev, cargs);
+ if (ret == GRUB_ERR_NONE)
+ break;
+ if (ret != GRUB_ERR_ACCESS_DENIED || tries == 1)
+ goto error;
+ grub_puts_ (N_("Invalid passphrase."));
+
+ /*
+ * Since recover_key() calls a function that returns grub_errno,
+ * a leftover error value from a previously rejected passphrase
+ * will trigger a phantom failure. We therefore clear it before
+ * trying a new passphrase.
+ */
+ grub_errno = GRUB_ERR_NONE;
+ }
+ }
ret = grub_cryptodisk_insert (dev, name, source);
if (ret != GRUB_ERR_NONE)
--
2.39.2
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