3 files changed, 71 insertions, 1 deletions

diff --git a/security/keys/compat.c b/security/keys/compat.c
index e10ec995f275..c766c68a63bc 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -79,6 +79,9 @@ asmlinkage long compat_sys_keyctl(u32 option,
         case KEYCTL_ASSUME_AUTHORITY:
                 return keyctl_assume_authority(arg2);
 
+        case KEYCTL_GET_SECURITY:
+                return keyctl_get_security(arg2, compat_ptr(arg3), arg4);
+
         default:
                 return -EOPNOTSUPP;
         }
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 3cc04c2afe1c..6361d3736dbc 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -155,7 +155,8 @@ extern long keyctl_negate_key(key_serial_t, unsigned, key_serial_t);
 extern long keyctl_set_reqkey_keyring(int);
 extern long keyctl_set_timeout(key_serial_t, unsigned);
 extern long keyctl_assume_authority(key_serial_t);
-
+extern long keyctl_get_security(key_serial_t keyid, char __user *buffer,
+                                size_t buflen);
 
 /*
  * debugging key validation
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 1698bf90ee84..56e963b700b9 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -20,6 +20,7 @@
 #include <linux/string.h>
 #include <linux/err.h>
 #include <linux/vmalloc.h>
+#include <linux/security.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -1080,6 +1081,66 @@ error:
 
 } /* end keyctl_assume_authority() */
 
+/*
+ * get the security label of a key
+ * - the key must grant us view permission
+ * - if there's a buffer, we place up to buflen bytes of data into it
+ * - unless there's an error, we return the amount of information available,
+ *   irrespective of how much we may have copied (including the terminal NUL)
+ * - implements keyctl(KEYCTL_GET_SECURITY)
+ */
+long keyctl_get_security(key_serial_t keyid,
+                         char __user *buffer,
+                         size_t buflen)
+{
+        struct key *key, *instkey;
+        key_ref_t key_ref;
+        char *context;
+        long ret;
+
+        key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
+        if (IS_ERR(key_ref)) {
+                if (PTR_ERR(key_ref) != -EACCES)
+                        return PTR_ERR(key_ref);
+
+                /* viewing a key under construction is also permitted if we
+                 * have the authorisation token handy */
+                instkey = key_get_instantiation_authkey(keyid);
+                if (IS_ERR(instkey))
+                        return PTR_ERR(key_ref);
+                key_put(instkey);
+
+                key_ref = lookup_user_key(NULL, keyid, 0, 1, 0);
+                if (IS_ERR(key_ref))
+                        return PTR_ERR(key_ref);
+        }
+
+        key = key_ref_to_ptr(key_ref);
+        ret = security_key_getsecurity(key, &context);
+        if (ret == 0) {
+                /* if no information was returned, give userspace an empty
+                 * string */
+                ret = 1;
+                if (buffer && buflen > 0 &&
+                    copy_to_user(buffer, "", 1) != 0)
+                        ret = -EFAULT;
+        } else if (ret > 0) {
+                /* return as much data as there's room for */
+                if (buffer && buflen > 0) {
+                        if (buflen > ret)
+                                buflen = ret;
+
+                        if (copy_to_user(buffer, context, buflen) != 0)
+                                ret = -EFAULT;
+                }
+
+                kfree(context);
+        }
+
+        key_ref_put(key_ref);
+        return ret;
+}
+
 /*****************************************************************************/
 /*
  * the key control system call
@@ -1160,6 +1221,11 @@ asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
         case KEYCTL_ASSUME_AUTHORITY:
                 return keyctl_assume_authority((key_serial_t) arg2);
 
+        case KEYCTL_GET_SECURITY:
+                return keyctl_get_security((key_serial_t) arg2,
+                                           (char *) arg3,
+                                           (size_t) arg4);
+
         default:
                 return -EOPNOTSUPP;
         }