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Re: [PATCH v3 1/3] cryptodisk: make the password getter and additional a
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From: |
Dmitry |
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Subject: |
Re: [PATCH v3 1/3] cryptodisk: make the password getter and additional argument to recover_key |
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Date: |
Thu, 31 Dec 2020 21:42:55 +0300 |
Hi,
Please see inline
чт, 31 дек. 2020 г. в 20:39, James Bottomley <jejb@linux.ibm.com>:
>
> For AMD SEV environments, the grub boot password has to be retrieved
> from a given memory location rather than prompted for. This means
> that the standard password getter needs to be replaced with one that
> gets the passphrase from the SEV area and uses that instead. Adding
> the password getter as a passed in argument to recover_key() makes
> this possible.
>
> Signed-off-by: James Bottomley <jejb@linux.ibm.com>
>
> ---
>
> v2: add conditional prompting to geli.c
> v3: make getter specify prompt requirement
> ---
> grub-core/disk/cryptodisk.c | 2 +-
> grub-core/disk/geli.c | 12 +++++++-----
> grub-core/disk/luks.c | 12 +++++++-----
> grub-core/disk/luks2.c | 12 +++++++-----
> grub-core/lib/crypto.c | 4 ++++
> grub-core/osdep/unix/password.c | 4 ++++
> grub-core/osdep/windows/password.c | 4 ++++
> include/grub/cryptodisk.h | 6 +++++-
> 8 files changed, 39 insertions(+), 17 deletions(-)
>
> diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
> index b62835acc..c51c2edb8 100644
> --- a/grub-core/disk/cryptodisk.c
> +++ b/grub-core/disk/cryptodisk.c
> @@ -1011,7 +1011,7 @@ grub_cryptodisk_scan_device_real (const char *name,
> grub_disk_t source)
> if (!dev)
> continue;
>
> - err = cr->recover_key (source, dev);
> + err = cr->recover_key (source, dev, grub_password_get);
> if (err)
> {
> cryptodisk_close (dev);
> diff --git a/grub-core/disk/geli.c b/grub-core/disk/geli.c
> index 2f34a35e6..3d826104d 100644
> --- a/grub-core/disk/geli.c
> +++ b/grub-core/disk/geli.c
> @@ -398,7 +398,8 @@ configure_ciphers (grub_disk_t disk, const char
> *check_uuid,
> }
>
> static grub_err_t
> -recover_key (grub_disk_t source, grub_cryptodisk_t dev)
> +recover_key (grub_disk_t source, grub_cryptodisk_t dev,
> + grub_passwd_cb *password_get)
> {
> grub_size_t keysize;
> grub_uint8_t digest[GRUB_CRYPTO_MAX_MDLEN];
> @@ -438,11 +439,12 @@ recover_key (grub_disk_t source, grub_cryptodisk_t dev)
> tmp = NULL;
> if (source->partition)
> tmp = grub_partition_get_name (source->partition);
> - grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
> - source->partition ? "," : "", tmp ? : "",
> - dev->uuid);
> + if (password_get (NULL, 0))
> + grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
> + source->partition ? "," : "", tmp ? : "",
> + dev->uuid);
> grub_free (tmp);
> - if (!grub_password_get (passphrase, MAX_PASSPHRASE))
> + if (!password_get (passphrase, MAX_PASSPHRASE))
> return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
>
> /* Calculate the PBKDF2 of the user supplied passphrase. */
> diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
> index 13103ea6a..13eee2a18 100644
> --- a/grub-core/disk/luks.c
> +++ b/grub-core/disk/luks.c
> @@ -152,7 +152,8 @@ configure_ciphers (grub_disk_t disk, const char
> *check_uuid,
>
> static grub_err_t
> luks_recover_key (grub_disk_t source,
> - grub_cryptodisk_t dev)
> + grub_cryptodisk_t dev,
> + grub_passwd_cb *password_get)
> {
> struct grub_luks_phdr header;
> grub_size_t keysize;
> @@ -187,11 +188,12 @@ luks_recover_key (grub_disk_t source,
> tmp = NULL;
> if (source->partition)
> tmp = grub_partition_get_name (source->partition);
> - grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
> - source->partition ? "," : "", tmp ? : "",
> - dev->uuid);
> + if (password_get (NULL, 0))
> + grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "),
> source->name,
> + source->partition ? "," : "", tmp ? : "",
> + dev->uuid);
> grub_free (tmp);
> - if (!grub_password_get (passphrase, MAX_PASSPHRASE))
> + if (!password_get (passphrase, MAX_PASSPHRASE))
> {
> grub_free (split_key);
> return grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
> diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
> index 7460d7b58..7597d8576 100644
> --- a/grub-core/disk/luks2.c
> +++ b/grub-core/disk/luks2.c
> @@ -542,7 +542,8 @@ luks2_decrypt_key (grub_uint8_t *out_key,
>
> static grub_err_t
> luks2_recover_key (grub_disk_t source,
> - grub_cryptodisk_t crypt)
> + grub_cryptodisk_t crypt,
> + grub_passwd_cb *password_get)
Do you have any thoughts for the future if we want to add luks header and
master key passing to this function?
I'm using my own branch where I added this in a trivial way:
static grub_err_t
luks2_recover_key (grub_disk_t source,
grub_cryptodisk_t crypt,
grub_file_t hdr_file, grub_file_t key_file, grub_file_t mkey_file)
https://gitlab.com/reagentoo/grub/-/blob/cryptopatch_tiny_v2/grub-core/disk/luks2.c#L571-573
But I'm at a loss to think of how this can be done in combination with
a 'grub_passwd_cb*'.
Best regards,
Dmitry
> {
> grub_uint8_t candidate_key[GRUB_CRYPTODISK_MAX_KEYLEN];
> char passphrase[MAX_PASSPHRASE], cipher[32];
> @@ -584,10 +585,11 @@ luks2_recover_key (grub_disk_t source,
> /* Get the passphrase from the user. */
> if (source->partition)
> part = grub_partition_get_name (source->partition);
> - grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
> - source->partition ? "," : "", part ? : "",
> - crypt->uuid);
> - if (!grub_password_get (passphrase, MAX_PASSPHRASE))
> + if (password_get (NULL, 0))
> + grub_printf_ (N_("Enter passphrase for %s%s%s (%s): "), source->name,
> + source->partition ? "," : "", part ? : "",
> + crypt->uuid);
> + if (!password_get (passphrase, MAX_PASSPHRASE))
> {
> ret = grub_error (GRUB_ERR_BAD_ARGUMENT, "Passphrase not supplied");
> goto err;
> diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c
> index ca334d5a4..34272a7ad 100644
> --- a/grub-core/lib/crypto.c
> +++ b/grub-core/lib/crypto.c
> @@ -456,6 +456,10 @@ grub_password_get (char buf[], unsigned buf_size)
> unsigned cur_len = 0;
> int key;
>
> + if (!buf)
> + /* want prompt */
> + return 1;
> +
> while (1)
> {
> key = grub_getkey ();
> diff --git a/grub-core/osdep/unix/password.c b/grub-core/osdep/unix/password.c
> index 9996b244b..365ac4bad 100644
> --- a/grub-core/osdep/unix/password.c
> +++ b/grub-core/osdep/unix/password.c
> @@ -34,6 +34,10 @@ grub_password_get (char buf[], unsigned buf_size)
> int tty_changed = 0;
> char *ptr;
>
> + if (!buf)
> + /* want prompt */
> + return 1;
> +
> grub_refresh ();
>
> /* Disable echoing. Based on glibc. */
> diff --git a/grub-core/osdep/windows/password.c
> b/grub-core/osdep/windows/password.c
> index 1d3af0c2c..2a6615611 100644
> --- a/grub-core/osdep/windows/password.c
> +++ b/grub-core/osdep/windows/password.c
> @@ -33,6 +33,10 @@ grub_password_get (char buf[], unsigned buf_size)
> DWORD mode = 0;
> char *ptr;
>
> + if (!buf)
> + /* want prompt */
> + return 1;
> +
> grub_refresh ();
>
> GetConsoleMode (hStdin, &mode);
> diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h
> index dcf17fbb3..737487bb4 100644
> --- a/include/grub/cryptodisk.h
> +++ b/include/grub/cryptodisk.h
> @@ -112,6 +112,9 @@ struct grub_cryptodisk
> };
> typedef struct grub_cryptodisk *grub_cryptodisk_t;
>
> +/* must match prototype for grub_password_get */
> +typedef int (grub_passwd_cb)(char buf[], unsigned buf_size);
> +
> struct grub_cryptodisk_dev
> {
> struct grub_cryptodisk_dev *next;
> @@ -119,7 +122,8 @@ struct grub_cryptodisk_dev
>
> grub_cryptodisk_t (*scan) (grub_disk_t disk, const char *check_uuid,
> int boot_only);
> - grub_err_t (*recover_key) (grub_disk_t disk, grub_cryptodisk_t dev);
> + grub_err_t (*recover_key) (grub_disk_t disk, grub_cryptodisk_t dev,
> + grub_passwd_cb *get_password);
password_get?
> };
> typedef struct grub_cryptodisk_dev *grub_cryptodisk_dev_t;
>
> --
> 2.26.2
>
>
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