[PATCH] keys: Permit key expiry time to be set

Add a new keyctl function that allows the expiry time to be set on a key or
removed from a key, provided the caller has attribute modification access.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Alexander Zangerl <az@bond.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 48 insertions, 0 deletions

diff --git a/security/keys/compat.c b/security/keys/compat.c
index 3303673c636e..e8e7ef4a290c 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -74,6 +74,9 @@ asmlinkage long compat_sys_keyctl(u32 option,
         case KEYCTL_SET_REQKEY_KEYRING:
                 return keyctl_set_reqkey_keyring(arg2);
 
+        case KEYCTL_SET_TIMEOUT:
+                return keyctl_set_timeout(arg2, arg3);
+
         default:
                 return -EOPNOTSUPP;
         }
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 39cba97c5eb9..51f37c0bdb32 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -136,6 +136,7 @@ extern long keyctl_instantiate_key(key_serial_t, const void __user *,
                                    size_t, key_serial_t);
 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);
 
 
 /*
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index b7a468fabdf9..299f0ae11cf0 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -967,6 +967,46 @@ long keyctl_set_reqkey_keyring(int reqkey_defl)
 
 /*****************************************************************************/
 /*
+ * set or clear the timeout for a key
+ */
+long keyctl_set_timeout(key_serial_t id, unsigned timeout)
+{
+        struct timespec now;
+        struct key *key;
+        key_ref_t key_ref;
+        time_t expiry;
+        long ret;
+
+        key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
+        if (IS_ERR(key_ref)) {
+                ret = PTR_ERR(key_ref);
+                goto error;
+        }
+
+        key = key_ref_to_ptr(key_ref);
+
+        /* make the changes with the locks held to prevent races */
+        down_write(&key->sem);
+
+        expiry = 0;
+        if (timeout > 0) {
+                now = current_kernel_time();
+                expiry = now.tv_sec + timeout;
+        }
+
+        key->expiry = expiry;
+
+        up_write(&key->sem);
+        key_put(key);
+
+        ret = 0;
+error:
+        return ret;
+
+} /* end keyctl_set_timeout() */
+
+/*****************************************************************************/
+/*
  * the key control system call
  */
 asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
@@ -1038,6 +1078,10 @@ asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
         case KEYCTL_SET_REQKEY_KEYRING:
                 return keyctl_set_reqkey_keyring(arg2);
 
+        case KEYCTL_SET_TIMEOUT:
+                return keyctl_set_timeout((key_serial_t) arg2,
+                                          (unsigned) arg3);
+
         default:
                 return -EOPNOTSUPP;
         }