Use the kernel "KEYS" subsystem to get a password for a card based on
the card's CID. This code was based on a patch set submitted by
Anderson Briglia in 2006.
Signed-off-by: Al Cooper <alcoop...@gmail.com>
---
drivers/mmc/core/Kconfig | 8 ++++
drivers/mmc/core/core.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/mmc/core/core.h | 11 ++++-
3 files changed, 123 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/core/Kconfig b/drivers/mmc/core/Kconfig
index 269d072..b0ba79d 100644
--- a/drivers/mmc/core/Kconfig
+++ b/drivers/mmc/core/Kconfig
@@ -26,3 +26,11 @@ config MMC_CLKGATE
support handling this in order for it to be of any use.
If unsure, say N.
+
+config MMC_LOCK
+ bool "MMC/SD password based card lock/unlock"
+ select KEYS
+ help
+ This will add the ability to lock/unlock SD and MMC cards.
+
+ If unsure, say N.
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 49a5bca..4954d04 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -27,6 +27,7 @@
#include <linux/fault-inject.h>
#include <linux/random.h>
#include <linux/slab.h>
+#include <linux/key-type.h>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
@@ -2705,6 +2706,104 @@ void mmc_init_context_info(struct mmc_host *host)
init_waitqueue_head(&host->context_info.wait);
}
+#ifdef CONFIG_MMC_LOCK
+
+static int mmc_key_instantiate(struct key *key,
+ struct key_preparsed_payload *prep)
+{
+ char *payload;
+
+ if (prep->datalen <= 0 || prep->datalen > MMC_PASSWORD_MAX ||
+ !prep->data) {
+ pr_warn("Invalid data\n");
+ return -EINVAL;
+ }
+
+ payload = kmalloc(prep->datalen, GFP_KERNEL);
+ if (!payload)
+ return -ENOMEM;
+ memcpy(payload, prep->data, prep->datalen);
+ key->payload.data = payload;
+ key->datalen = prep->datalen;
+ return 0;
+}
+
+static int mmc_key_match(const struct key *key, const void *description)
+{
+ pr_debug("mmc_key_match: %s, %s\n",
+ key->description, (char *)description);
+ return strcmp(key->description, description) == 0;
+}
+
+/*
+ * dispose of the data dangling from the corpse of a mmc key
+ */
+static void mmc_key_destroy(struct key *key)
+{
+ kfree(key->payload.data);
+}
+
+struct key_type key_type_mmc = {
+ .name = "mmc",
+ .instantiate = mmc_key_instantiate,
+ .match = mmc_key_match,
+ .destroy = mmc_key_destroy,
+};
+
+int mmc_get_password(struct mmc_card *card, struct mmc_password *password)
+{
+ struct key *mmc_key;
+ char key_desc[(sizeof(card->raw_cid) * 2) + 1];
+
+ /* Use the CID to uniquely identify the card */
+ snprintf(key_desc, sizeof(key_desc), "%08x%08x%08x%08x",
+ card->raw_cid[0], card->raw_cid[1],
+ card->raw_cid[2], card->raw_cid[3]);
+
+ mmc_key = request_key(&key_type_mmc, key_desc,
+ "password");
+ if (IS_ERR(mmc_key)) {
+ dev_warn(&card->dev, "Error, request_key %ld\n",
+ PTR_ERR(mmc_key));
+ return PTR_ERR(mmc_key);
+ }
+ dev_dbg(&card->dev, "Found matching key\n");
+ memcpy(&password->password, mmc_key->payload.data,
+ mmc_key->datalen);
+ password->length = mmc_key->datalen;
+ key_put(mmc_key);
+
+ return 0;
+}
+
+static inline int mmc_register_key_type(void)
+{
+ return register_key_type(&key_type_mmc);
+}
+
+static inline void mmc_unregister_key_type(void)
+{
+ unregister_key_type(&key_type_mmc);
+}
+
+#else /* CONFIG_MMC_LOCK */
+
+int mmc_get_password(struct mmc_card *card, struct mmc_password *password)
+{
+ return -ENOKEY;
+}
+
+static inline int mmc_register_key_type(void)
+{
+ return 0;
+}
+
+static inline void mmc_unregister_key_type(void)
+{
+}
+
+#endif /* CONFIG_MMC_LOCK */
+
static int __init mmc_init(void)
{
int ret;
@@ -2725,8 +2824,13 @@ static int __init mmc_init(void)
if (ret)
goto unregister_host_class;
+ ret = mmc_register_key_type();
+ if (ret)
+ goto unregister_sdio_bus;
return 0;
+unregister_sdio_bus:
+ sdio_unregister_bus();
unregister_host_class:
mmc_unregister_host_class();
unregister_bus:
@@ -2739,6 +2843,7 @@ destroy_workqueue:
static void __exit mmc_exit(void)
{
+ mmc_unregister_key_type();
sdio_unregister_bus();
mmc_unregister_host_class();
mmc_unregister_bus();
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 5345d15..c64ec12 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -81,5 +81,14 @@ void mmc_add_card_debugfs(struct mmc_card *card);
void mmc_remove_card_debugfs(struct mmc_card *card);
void mmc_init_context_info(struct mmc_host *host);
-#endif
+/* Lock/Unlock functionality */
+#define MMC_PASSWORD_MAX 16
+struct mmc_password {
+ char password[MMC_PASSWORD_MAX];
+ int length;
+};
+int mmc_unlock_card(struct mmc_card *card);
+int mmc_get_password(struct mmc_card *card, struct mmc_password *password);
+
+#endif
--
1.8.1.3
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