Re: [PATCH 4/4] Add MMC Password Protection (lock/unlock) support V9: mmc_sysfs.diff

[Anderson Briglia <anderson.briglia@indt.org.br>]

Hi Pierre,

Sorry about the delay.
I changed a bit the code to align with your latest suggestions.

ext Pierre Ossman wrote:
> I've queued it up for -mm, but there a few more comments I want resolved
> before this can move to Linus...
> 
> You need to clean up mmc_lockable_store(). It had a few broken variable
> declarations that even prevented it from compiling, and after I fixed
> that I still get:
> 
> drivers/mmc/mmc_sysfs.c: In function ‘mmc_lockable_store’:
> drivers/mmc/mmc_sysfs.c:160: warning: ignoring return value of
> ‘device_attach’, declared with attribute warn_unused_result
> drivers/mmc/mmc_sysfs.c:93: warning: ‘mmc_key’ may be used uninitialized
> in this function

I'm not getting those errors anymore.
> 
> There's also no handling for an invalid string written to the sysfs node.

I believe now it is ok. If you send an invalid string to sysfs it will return -EINVAL.
> 
> And third, you're a bit excessive on the goto:s. E.g. out_unlocked is
> used in a single place, so it is completely unnecessary. Please do a
> general cleanup of the control flow.

I believe now the number of goto's is ok.

Regards,

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@indt.org.br>
Signed-off-by: Anderson Lizardo <anderson.lizardo@indt.org.br>
Signed-off-by: Anderson Briglia <anderson.briglia@indt.org.br>

Index: linux-linus-2.6/drivers/mmc/mmc_sysfs.c
===================================================================
--- linux-linus-2.6.orig/drivers/mmc/mmc_sysfs.c	2007-01-29 14:26:21.000000000 -0400
+++ linux-linus-2.6/drivers/mmc/mmc_sysfs.c	2007-01-29 14:28:19.000000000 -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 +66,102 @@ 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);
+	int ret;
+
+	ret = mmc_card_claim_host(card);
+	if ((ret != MMC_ERR_NONE) || (!mmc_card_lockable(card)))
+		return -EINVAL;
+
+	ret = -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);
+		ret = len;
+		goto out;
+	} 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)) {
+			ret =  mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_CLR_PWD);
+			if (!ret) {
+				ret = len;
+			}	goto out;
+		} 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)) ||
+					      (!strncmp(data, "change", 6)))) {
+		/* assign or change */
+		struct key *mmc_key;
+
+		if(!(strncmp(data, "assign", 6)))
+			mmc_key = request_key(&mmc_key_type, "mmc:key", "assign");
+		else
+			mmc_key = request_key(&mmc_key_type, "mmc:key", "change");
+
+		if (!IS_ERR(mmc_key)) {
+			ret =  mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_SET_PWD);
+			if (!ret) {
+				ret = len;
+				goto out;
+			}
+		} 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)) {
+			ret = mmc_lock_unlock(card, mmc_key, MMC_LOCK_MODE_UNLOCK);
+			if (ret) {
+				dev_dbg(&card->dev, "Wrong password\n");
+				ret = -EINVAL;
+				goto out;
+			}
+			else {
+				mmc_card_release_host(card);
+				device_release_driver(dev);
+				ret = device_attach(dev);
+				if(!ret)
+					return -EINVAL;
+				else
+					return len;
+			}
+		} else
+			dev_dbg(&card->dev, "request_key returned error %ld\n", PTR_ERR(mmc_key));
+	}
+out:
+	mmc_card_release_host(card);
+	return ret;
+}
+
+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 +331,11 @@ 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 +350,9 @@ 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);
 	}