[patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[Anderson Briglia]

Implement MMC password force erase, remove password, change password,
unlock card and assign password operations. It uses the sysfs mechanism
to send commands to the MMC subsystem.

Signed-off-by: Carlos Eduardo Aguiar <carlos.aguiar <at> indt.org.br>
Signed-off-by: Anderson Lizardo <anderson.lizardo <at> indt.org.br>
Signed-off-by: Anderson Briglia <anderson.briglia <at> indt.org.br>

Index: linux-omap-2.6.git/drivers/mmc/mmc_sysfs.c
===================================================================
--- linux-omap-2.6.git.orig/drivers/mmc/mmc_sysfs.c	2006-11-22 09:07:23.000000000 -0400
+++ linux-omap-2.6.git/drivers/mmc/mmc_sysfs.c	2006-11-22 09:18:58.000000000 -0400
@@ -17,6 +17,7 @@
  #include <linux/idr.h>
  #include <linux/workqueue.h>
  #include <linux/key.h>
+#include <linux/err.h>

  #include <linux/mmc/card.h>
  #include <linux/mmc/host.h>
@@ -65,6 +66,94 @@ static struct device_attribute mmc_dev_a

  static struct device_attribute mmc_dev_attr_scr = MMC_ATTR_RO(scr);

+#ifdef	CONFIG_MMC_PASSWORDS
+
+static ssize_t
+mmc_lockable_show(struct device *dev, struct device_attribute *att, char *buf)
+{
+	struct mmc_card *card = dev_to_mmc_card(dev);
+
+	if (!mmc_card_lockable(card))
+		return sprintf(buf, "unsupported\n");
+	else
+		return sprintf(buf, "%slocked\n", mmc_card_locked(card) ?
+			"" : "un");
+}
+
+/*
+ * implement MMC password functions: force erase, remove password, change
+ * password, unlock card and assign password.
+ */
+static ssize_t
+mmc_lockable_store(struct device *dev, struct device_attribute *att,
+	const char *data, size_t len)
+{
+	struct mmc_card *card = dev_to_mmc_card(dev);
+
+	if (!mmc_card_lockable(card))
+		return -EINVAL;
+
+	if (mmc_card_locked(card) && !strncmp(data, "erase", 5)) {
+		/* forced erase only works while card is locked */
+		mmc_lock_unlock(card, NULL, MMC_LOCK_MODE_ERASE);
+		return len;
+	} else if (!mmc_card_locked(card) && !strncmp(data, "remove", 6)) {
+		/* remove password only works while card is unlocked */
+		struct key *mmc_key = request_key(&mmc_key_type, "mmc:key", "remove");
+
+		if (!IS_ERR(mmc_key)) {
+			int err =  mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_CLR_PWD);
+			if (!err)
+				return len;
+		} else
+			dev_dbg(&card->dev, "request_key returned error %ld\n", PTR_ERR(mmc_key));
+	} else if (!mmc_card_locked(card) && !strncmp(data, "change", 6)) {
+			/* change */
+			struct key *mmc_key = request_key(&mmc_key_type, "mmc:key", "change");
+
+			if (!IS_ERR(mmc_key)) {
+				int err =  mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_SET_PWD);
+				if (!err)
+					return len;
+			} else
+				dev_dbg(&card->dev, "request_key returned error %ld\n", PTR_ERR(mmc_key));
+	} else if (mmc_card_locked(card) && !strncmp(data, "unlock", 6)) {
+			/* unlock */
+			struct key *mmc_key = request_key(&mmc_key_type, "mmc:key", "unlock");
+
+			if (!IS_ERR(mmc_key)) {
+				int err = mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_UNLOCK);
+				if (err) {
+					dev_dbg(&card->dev, "Wrong password\n");
+				}
+				else {
+					device_release_driver(dev);
+					device_attach(dev);
+					return len;
+				}
+			} else
+				dev_dbg(&card->dev, "request_key returned error %ld\n", PTR_ERR(mmc_key));
+	} else if (!mmc_card_locked(card) && !strncmp(data, "assign", 6)) {
+			/* assign */
+			struct key *mmc_key = request_key(&mmc_key_type, "mmc:key", "assign");
+
+			if (!IS_ERR(mmc_key)) {
+				int err = mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_SET_PWD);
+				if (!err)
+					return len;
+			} else
+				dev_dbg(&card->dev, "request_key returned error %ld\n", PTR_ERR(mmc_key));
+	}
+
+	return -EINVAL;
+}
+
+static struct device_attribute mmc_dev_attr_lockable =
+	__ATTR(lockable, S_IWUSR | S_IRUGO,
+		 mmc_lockable_show, mmc_lockable_store);
+
+#endif
+

  static void mmc_release_card(struct device *dev)
  {
@@ -234,6 +323,11 @@ int mmc_register_card(struct mmc_card *c
  			if (ret)
  				device_del(&card->dev);
  		}
+#ifdef CONFIG_MMC_PASSWORDS
+		ret = device_create_file(&card->dev, &mmc_dev_attr_lockable);
+		if (ret)
+			device_del(&card->dev);
+#endif
  	}
  	return ret;
  }
@@ -248,6 +342,9 @@ void mmc_remove_card(struct mmc_card *ca
  		if (mmc_card_sd(card))
  			device_remove_file(&card->dev, &mmc_dev_attr_scr);

+#ifdef CONFIG_MMC_PASSWORDS
+		device_remove_file(&card->dev, &mmc_dev_attr_lockable);
+#endif
  		device_del(&card->dev);
  	}

Re: [patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[Pierre Ossman]

Patch looks ok. But I never got an answer what the difference between
"change" and "assign" is.

Rgds

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

Re: [patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[Anderson Briglia]

Hi Pierre,

ext Pierre Ossman wrote:
> Patch looks ok. But I never got an answer what the difference between
> "change" and "assign" is.

You're right, the command is the same, but the difference is the password's
length and password itself sent to the card.
According to MMC spec 4.1, when a password replacement is done, the length value
(PWD_LEN) shall include both passwords, the old and the new one, and the password
(PWD) shall include the old (currently) followed by the new password.

Best Regards,

Anderson Briglia

Re: [patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[Pierre Ossman]

Anderson Briglia wrote:
> Hi Pierre,
>
> ext Pierre Ossman wrote:
>> Patch looks ok. But I never got an answer what the difference between
>> "change" and "assign" is.
>
> You're right, the command is the same, but the difference is the
> password's
> length and password itself sent to the card.
> According to MMC spec 4.1, when a password replacement is done, the
> length value
> (PWD_LEN) shall include both passwords, the old and the new one, and
> the password
> (PWD) shall include the old (currently) followed by the new password.

So shouldn't this be something that userspace handles?

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

Re: [patch 4/5] [RFC] Add MMC Password Protection (lock/unlock) support V7: mmc_sysfs.diff

[Anderson Briglia]

ext Pierre Ossman wrote:
> Anderson Briglia wrote:
>> Hi Pierre,
>>
>> ext Pierre Ossman wrote:
>>> Patch looks ok. But I never got an answer what the difference between
>>> "change" and "assign" is.
>> You're right, the command is the same, but the difference is the
>> password's
>> length and password itself sent to the card.
>> According to MMC spec 4.1, when a password replacement is done, the
>> length value
>> (PWD_LEN) shall include both passwords, the old and the new one, and
>> the password
>> (PWD) shall include the old (currently) followed by the new password.
> 
> So shouldn't this be something that userspace handles?
> 

I merged the code for "change" and "assign". But the action (returned from kernel
to user space application continues as "change" and "assign" separately.

Anderson Briglia