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Subject[RFC PATCH 2/2] dm-crypt: Use any key type which is registered
Date
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 <franck.lenormand@nxp.com>
---
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);
+
+ /* Search the key type in the list */
+ list_for_each_entry(p, &key_types_list, link) {
+ if (string_size) {
+ if (strncmp(p->name, type_name, string_size) == 0) {
+ ktype = p;
+ break;
+ }
+ } else {
+ if (strcmp(p->name, type_name) == 0) {
+ ktype = p;
+ break;
+ }
+ }
+ }
+
+ up_read(&key_types_sem);
+
+ return ktype;
+}
+EXPORT_SYMBOL(get_key_type);
+
/*
* Initialise the key management state.
*/
--
2.7.4
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