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[v4,4/6] KEYS: Add an optional lookup_restrict hook to key_type

Message ID 20160707205337.2061-5-mathew.j.martineau@linux.intel.com
State New, archived
Headers show

Commit Message

Mat Martineau July 7, 2016, 8:53 p.m. UTC
The restrict_link functions used to validate keys as they are linked
to a keyring can be associated with specific key types.  Each key type
may be loaded (or not) at runtime, so lookup of restrict_link
functions needs to be part of the key type implementation to ensure
that the requested keys can be examined.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
 Documentation/security/keys.txt | 8 ++++++++
 include/linux/key-type.h        | 8 ++++++++
 2 files changed, 16 insertions(+)
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diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt
index cfb86c5..45f5ff8e 100644
--- a/Documentation/security/keys.txt
+++ b/Documentation/security/keys.txt
@@ -1645,6 +1645,14 @@  The structure has a number of fields, some of which are mandatory:
      If successful, 0 will be returned.  If the key doesn't support this,
      EOPNOTSUPP will be returned.
+ (*) restrict_link_func_t (*lookup_restrict)(const char *restriction);
+     This optional method is used to enable userspace configuration of
+     keyring restrictions. The value assigned to the "restrict_by"
+     option at keyring creation is passed in, and this method returns
+     a pointer to the restrict_link function associated with that
+     name. If there is no match, -EINVAL is returned.
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 63b2a92..7b30d3a 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -158,6 +158,14 @@  struct key_type {
 	int (*asym_verify_signature)(struct kernel_pkey_params *params,
 				     const void *in, const void *in2);
+	/* Look up a keyring access restrict function (optional)
+	 *
+	 * - NULL is a valid return value (meaning the requested restriction
+	 *   is known but will never block addition of a key)
+	 * - should return -EINVAL if the restriction is unknown
+	 */
+	restrict_link_func_t (*lookup_restrict)(const char *restriction);
 	/* internal fields */
 	struct list_head	link;		/* link in types list */
 	struct lock_class_key	lock_class;	/* key->sem lock class */