There was only 2 key_type supported by dm-crypt which limits other
implementations.

This patch allows to use any key_type which is registered obtaining
the key_type from key framework.

This also remove the compilation dependency between dm-crypt and
key implementations.

Signed-off-by: Franck LENORMAND <redacted>
---
  drivers/md/dm-crypt.c    | 11 ++++++-----
  include/linux/key-type.h |  2 ++
  security/keys/key.c      | 42 ++++++++++++++++++++++++++++++++++++++++++
  3 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index dd538e6..e25efc2 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c

@@ -35,6 +35,7 @@
  #include <crypto/authenc.h>
  #include <linux/rtnetlink.h> /* for struct rtattr and RTA macros only */
  #include <keys/user-type.h>
+#include <linux/key-type.h>
  
  #include <linux/device-mapper.h>
  

@@ -2010,6 +2011,7 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
  	int ret;
  	struct key *key;
  	const struct user_key_payload *ukp;
+	struct key_type *type;
  
  	/*
  	 * Reject key_string with whitespace. dm core currently lacks code for

@@ -2025,16 +2027,15 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
  	if (!key_desc || key_desc == key_string || !strlen(key_desc + 1))
  		return -EINVAL;
  
-	if (strncmp(key_string, "logon:", key_desc - key_string + 1) &&
-	    strncmp(key_string, "user:", key_desc - key_string + 1))
-		return -EINVAL;
+	type = get_key_type(key_string, key_desc - key_string);
+	if (!type)
+		return -ENOENT;
  
  	new_key_string = kstrdup(key_string, GFP_KERNEL);
  	if (!new_key_string)
  		return -ENOMEM;
  
-	key = request_key(key_string[0] == 'l' ? &key_type_logon : &key_type_user,
-			  key_desc + 1, NULL);
+	key = request_key(type, key_desc + 1, NULL);
  	if (IS_ERR(key)) {
  		kzfree(new_key_string);
  		return PTR_ERR(key);

diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index bc9af55..2b2167b 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h

@@ -176,6 +176,8 @@ extern struct key_type key_type_keyring;
  extern int register_key_type(struct key_type *ktype);
  extern void unregister_key_type(struct key_type *ktype);
  
+extern struct key_type *get_key_type(const char *type_name, size_t string_size);
+
  extern int key_payload_reserve(struct key *key, size_t datalen);
  extern int key_instantiate_and_link(struct key *key,
  				    const void *data,

diff --git a/security/keys/key.c b/security/keys/key.c
index 44a80d6..ef76114 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c

@@ -1156,6 +1156,48 @@ void unregister_key_type(struct key_type *ktype)
  }
  EXPORT_SYMBOL(unregister_key_type);
  
+/**
+ * get_key_type - Get the type of key using its name
+ * @type_name: Name of the key type to get
+ * @string_size: Size of the string to match
+ *
+ * The functions support null ended string (string_size == 0) as well as
+ * pointer on a string matching a number of characters (string_size > 0)
+ *
+ * Returns a pointer on the key type if successful, -ENOENT if the key type
+ * is not registered.
+ */
+struct key_type *get_key_type(const char *type_name, size_t string_size)
+{
+	struct key_type *p;
+	struct key_type *ktype = ERR_PTR(-ENOENT);
+
+	if (!type_name)
+		return ktype;
+
+	down_write(&key_types_sem);