1 files changed, 271 insertions, 285 deletions

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 557500110a13..6381e616c477 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -1,6 +1,6 @@
-/* request_key.c: request a key from userspace
+/* Request a key from userspace
  *
- * Copyright (C) 2004-6 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
@@ -18,27 +18,54 @@
 #include <linux/keyctl.h>
 #include "internal.h"
 
-struct key_construction {
-        struct list_head        link;   /* link in construction queue */
-        struct key              *key;   /* key being constructed */
-};
+/*
+ * wait_on_bit() sleep function for uninterruptible waiting
+ */
+static int key_wait_bit(void *flags)
+{
+        schedule();
+        return 0;
+}
+
+/*
+ * wait_on_bit() sleep function for interruptible waiting
+ */
+static int key_wait_bit_intr(void *flags)
+{
+        schedule();
+        return signal_pending(current) ? -ERESTARTSYS : 0;
+}
+
+/*
+ * call to complete the construction of a key
+ */
+void complete_request_key(struct key_construction *cons, int error)
+{
+        kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
 
-/* when waiting for someone else's keys, you get added to this */
-DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
+        if (error < 0)
+                key_negate_and_link(cons->key, key_negative_timeout, NULL,
+                                    cons->authkey);
+        else
+                key_revoke(cons->authkey);
+
+        key_put(cons->key);
+        key_put(cons->authkey);
+        kfree(cons);
+}
+EXPORT_SYMBOL(complete_request_key);
 
-/*****************************************************************************/
 /*
  * request userspace finish the construction of a key
  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
  */
-static int call_sbin_request_key(struct key *key,
-                                 struct key *authkey,
+static int call_sbin_request_key(struct key_construction *cons,
                                  const char *op,
                                  void *aux)
 {
         struct task_struct *tsk = current;
         key_serial_t prkey, sskey;
-        struct key *keyring;
+        struct key *key = cons->key, *authkey = cons->authkey, *keyring;
         char *argv[9], *envp[3], uid_str[12], gid_str[12];
         char key_str[12], keyring_str[3][12];
         char desc[20];
@@ -82,8 +109,7 @@ static int call_sbin_request_key(struct key *key,
                 rcu_read_lock();
                 sskey = rcu_dereference(tsk->signal->session_keyring)->serial;
                 rcu_read_unlock();
-        }
-        else {
+        } else {
                 sskey = tsk->user->session_keyring->serial;
         }
 
@@ -110,228 +136,77 @@ static int call_sbin_request_key(struct key *key,
         /* do it */
         ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
                                        UMH_WAIT_PROC);
+        kdebug("usermode -> 0x%x", ret);
+        if (ret >= 0) {
+                /* ret is the exit/wait code */
+                if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
+                    key_validate(key) < 0)
+                        ret = -ENOKEY;
+                else
+                        /* ignore any errors from userspace if the key was
+                         * instantiated */
+                        ret = 0;
+        }
 
 error_link:
         key_put(keyring);
 
 error_alloc:
         kleave(" = %d", ret);
+        complete_request_key(cons, ret);
         return ret;
+}
 
-} /* end call_sbin_request_key() */
-
-/*****************************************************************************/
 /*
- * call out to userspace for the key
- * - called with the construction sem held, but the sem is dropped here
+ * call out to userspace for key construction
  * - we ignore program failure and go on key status instead
  */
-static struct key *__request_key_construction(struct key_type *type,
-                                              const char *description,
-                                              const char *callout_info,
-                                              void *aux,
-                                              unsigned long flags)
+static int construct_key(struct key *key, const char *callout_info, void *aux)
 {
+        struct key_construction *cons;
         request_key_actor_t actor;
-        struct key_construction cons;
-        struct timespec now;
-        struct key *key, *authkey;
-        int ret, negated;
+        struct key *authkey;
+        int ret;
 
-        kenter("%s,%s,%s,%lx", type->name, description, callout_info, flags);
+        kenter("%d,%s,%p", key->serial, callout_info, aux);
 
-        /* create a key and add it to the queue */
-        key = key_alloc(type, description,
-                        current->fsuid, current->fsgid, current, KEY_POS_ALL,
-                        flags);
-        if (IS_ERR(key))
-                goto alloc_failed;
-
-        set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
-
-        cons.key = key;
-        list_add_tail(&cons.link, &key->user->consq);
-
-        /* we drop the construction sem here on behalf of the caller */
-        up_write(&key_construction_sem);
+        cons = kmalloc(sizeof(*cons), GFP_KERNEL);
+        if (!cons)
+                return -ENOMEM;
 
         /* allocate an authorisation key */
         authkey = request_key_auth_new(key, callout_info);
         if (IS_ERR(authkey)) {
+                kfree(cons);
                 ret = PTR_ERR(authkey);
                 authkey = NULL;
-                goto alloc_authkey_failed;
-        }
-
-        /* make the call */
-        actor = call_sbin_request_key;
-        if (type->request_key)
-                actor = type->request_key;
-        ret = actor(key, authkey, "create", aux);
-        if (ret < 0)
-                goto request_failed;
-
-        /* if the key wasn't instantiated, then we want to give an error */
-        ret = -ENOKEY;
-        if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
-                goto request_failed;
-
-        key_revoke(authkey);
-        key_put(authkey);
-
-        down_write(&key_construction_sem);
-        list_del(&cons.link);
-        up_write(&key_construction_sem);
-
-        /* also give an error if the key was negatively instantiated */
-check_not_negative:
-        if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
-                key_put(key);
-                key = ERR_PTR(-ENOKEY);
-        }
-
-out:
-        kleave(" = %p", key);
-        return key;
-
-request_failed:
-        key_revoke(authkey);
-        key_put(authkey);
-
-alloc_authkey_failed:
-        /* it wasn't instantiated
-         * - remove from construction queue
-         * - mark the key as dead
-         */
-        negated = 0;
-        down_write(&key_construction_sem);
-
-        list_del(&cons.link);
-
-        /* check it didn't get instantiated between the check and the down */
-        if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
-                set_bit(KEY_FLAG_NEGATIVE, &key->flags);
-                set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
-                negated = 1;
-        }
-
-        clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
-
-        up_write(&key_construction_sem);
-
-        if (!negated)
-                goto check_not_negative; /* surprisingly, the key got
-                                          * instantiated */
-
-        /* set the timeout and store in the session keyring if we can */
-        now = current_kernel_time();
-        key->expiry = now.tv_sec + key_negative_timeout;
-
-        if (current->signal->session_keyring) {
-                struct key *keyring;
-
-                rcu_read_lock();
-                keyring = rcu_dereference(current->signal->session_keyring);
-                atomic_inc(&keyring->usage);
-                rcu_read_unlock();
-
-                key_link(keyring, key);
-                key_put(keyring);
-        }
-
-        key_put(key);
-
-        /* notify anyone who was waiting */
-        wake_up_all(&request_key_conswq);
-
-        key = ERR_PTR(ret);
-        goto out;
-
-alloc_failed:
-        up_write(&key_construction_sem);
-        goto out;
-
-} /* end __request_key_construction() */
-
-/*****************************************************************************/
-/*
- * call out to userspace to request the key
- * - we check the construction queue first to see if an appropriate key is
- *   already being constructed by userspace
- */
-static struct key *request_key_construction(struct key_type *type,
-                                            const char *description,
-                                            const char *callout_info,
-                                            void *aux,
-                                            struct key_user *user,
-                                            unsigned long flags)
-{
-        struct key_construction *pcons;
-        struct key *key, *ckey;
-
-        DECLARE_WAITQUEUE(myself, current);
-
-        kenter("%s,%s,{%d},%s,%lx",
-               type->name, description, user->uid, callout_info, flags);
-
-        /* see if there's such a key under construction already */
-        down_write(&key_construction_sem);
-
-        list_for_each_entry(pcons, &user->consq, link) {
-                ckey = pcons->key;
-
-                if (ckey->type != type)
-                        continue;
-
-                if (type->match(ckey, description))
-                        goto found_key_under_construction;
+        } else {
+                cons->authkey = key_get(authkey);
+                cons->key = key_get(key);
+
+                /* make the call */
+                actor = call_sbin_request_key;
+                if (key->type->request_key)
+                        actor = key->type->request_key;
+
+                ret = actor(cons, "create", aux);
+
+                /* check that the actor called complete_request_key() prior to
+                 * returning an error */
+                WARN_ON(ret < 0 &&
+                        !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
+                key_put(authkey);
         }
 
-        /* see about getting userspace to construct the key */
-        key = __request_key_construction(type, description, callout_info, aux,
-                                         flags);
- error:
-        kleave(" = %p", key);
-        return key;
-
-        /* someone else has the same key under construction
-         * - we want to keep an eye on their key
-         */
- found_key_under_construction:
-        atomic_inc(&ckey->usage);
-        up_write(&key_construction_sem);
-
-        /* wait for the key to be completed one way or another */
-        add_wait_queue(&request_key_conswq, &myself);
-
-        for (;;) {
-                set_current_state(TASK_INTERRUPTIBLE);
-                if (!test_bit(KEY_FLAG_USER_CONSTRUCT, &ckey->flags))
-                        break;
-                if (signal_pending(current))
-                        break;
-                schedule();
-        }
-
-        set_current_state(TASK_RUNNING);
-        remove_wait_queue(&request_key_conswq, &myself);
-
-        /* we'll need to search this process's keyrings to see if the key is
-         * now there since we can't automatically assume it's also available
-         * there */
-        key_put(ckey);
-        ckey = NULL;
-
-        key = NULL; /* request a retry */
-        goto error;
-
-} /* end request_key_construction() */
+        kleave(" = %d", ret);
+        return ret;
+}
 
-/*****************************************************************************/
 /*
- * link a freshly minted key to an appropriate destination keyring
+ * link a key to the appropriate destination keyring
+ * - the caller must hold a write lock on the destination keyring
  */
-static void request_key_link(struct key *key, struct key *dest_keyring)
+static void construct_key_make_link(struct key *key, struct key *dest_keyring)
 {
         struct task_struct *tsk = current;
         struct key *drop = NULL;
@@ -363,11 +238,11 @@ static void request_key_link(struct key *key, struct key *dest_keyring)
                                 break;
 
                 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
-                        dest_keyring = current->user->session_keyring;
+                        dest_keyring = tsk->user->session_keyring;
                         break;
 
                 case KEY_REQKEY_DEFL_USER_KEYRING:
-                        dest_keyring = current->user->uid_keyring;
+                        dest_keyring = tsk->user->uid_keyring;
                         break;
 
                 case KEY_REQKEY_DEFL_GROUP_KEYRING:
@@ -377,15 +252,115 @@ static void request_key_link(struct key *key, struct key *dest_keyring)
         }
 
         /* and attach the key to it */
-        key_link(dest_keyring, key);
-
+        __key_link(dest_keyring, key);
         key_put(drop);
-
         kleave("");
+}
 
-} /* end request_key_link() */
+/*
+ * allocate a new key in under-construction state and attempt to link it in to
+ * the requested place
+ * - may return a key that's already under construction instead
+ */
+static int construct_alloc_key(struct key_type *type,
+                               const char *description,
+                               struct key *dest_keyring,
+                               unsigned long flags,
+                               struct key_user *user,
+                               struct key **_key)
+{
+        struct key *key;
+        key_ref_t key_ref;
+
+        kenter("%s,%s,,,", type->name, description);
+
+        mutex_lock(&user->cons_lock);
+
+        key = key_alloc(type, description,
+                        current->fsuid, current->fsgid, current, KEY_POS_ALL,
+                        flags);
+        if (IS_ERR(key))
+                goto alloc_failed;
+
+        set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
+
+        if (dest_keyring)
+                down_write(&dest_keyring->sem);
+
+        /* attach the key to the destination keyring under lock, but we do need
+         * to do another check just in case someone beat us to it whilst we
+         * waited for locks */
+        mutex_lock(&key_construction_mutex);
+
+        key_ref = search_process_keyrings(type, description, type->match,
+                                          current);
+        if (!IS_ERR(key_ref))
+                goto key_already_present;
+
+        if (dest_keyring)
+                construct_key_make_link(key, dest_keyring);
+
+        mutex_unlock(&key_construction_mutex);
+        if (dest_keyring)
+                up_write(&dest_keyring->sem);
+        mutex_unlock(&user->cons_lock);
+        *_key = key;
+        kleave(" = 0 [%d]", key_serial(key));
+        return 0;
+
+key_already_present:
+        mutex_unlock(&key_construction_mutex);
+        if (dest_keyring)
+                up_write(&dest_keyring->sem);
+        mutex_unlock(&user->cons_lock);
+        key_put(key);
+        *_key = key = key_ref_to_ptr(key_ref);
+        kleave(" = -EINPROGRESS [%d]", key_serial(key));
+        return -EINPROGRESS;
+
+alloc_failed:
+        mutex_unlock(&user->cons_lock);
+        *_key = NULL;
+        kleave(" = %ld", PTR_ERR(key));
+        return PTR_ERR(key);
+}
+
+/*
+ * commence key construction
+ */
+static struct key *construct_key_and_link(struct key_type *type,
+                                          const char *description,
+                                          const char *callout_info,
+                                          void *aux,
+                                          struct key *dest_keyring,
+                                          unsigned long flags)
+{
+        struct key_user *user;
+        struct key *key;
+        int ret;
+
+        user = key_user_lookup(current->fsuid);
+        if (!user)
+                return ERR_PTR(-ENOMEM);
+
+        ret = construct_alloc_key(type, description, dest_keyring, flags, user,
+                                  &key);
+        key_user_put(user);
+
+        if (ret == 0) {
+                ret = construct_key(key, callout_info, aux);
+                if (ret < 0)
+                        goto construction_failed;
+        }
+
+        return key;
+
+construction_failed:
+        key_negate_and_link(key, key_negative_timeout, NULL, NULL);
+        key_put(key);
+        return ERR_PTR(ret);
+}
 
-/*****************************************************************************/
 /*
  * request a key
  * - search the process's keyrings
@@ -400,7 +375,6 @@ struct key *request_key_and_link(struct key_type *type,
                                  struct key *dest_keyring,
                                  unsigned long flags)
 {
-        struct key_user *user;
         struct key *key;
         key_ref_t key_ref;
 
@@ -412,112 +386,124 @@ struct key *request_key_and_link(struct key_type *type,
         key_ref = search_process_keyrings(type, description, type->match,
                                           current);
 
-        kdebug("search 1: %p", key_ref);
-
         if (!IS_ERR(key_ref)) {
                 key = key_ref_to_ptr(key_ref);
-        }
-        else if (PTR_ERR(key_ref) != -EAGAIN) {
+        } else if (PTR_ERR(key_ref) != -EAGAIN) {
                 key = ERR_PTR(PTR_ERR(key_ref));
-        }
-        else  {
+        } else  {
                 /* the search failed, but the keyrings were searchable, so we
                  * should consult userspace if we can */
                 key = ERR_PTR(-ENOKEY);
                 if (!callout_info)
                         goto error;
 
-                /* - get hold of the user's construction queue */
-                user = key_user_lookup(current->fsuid);
-                if (!user)
-                        goto nomem;
-
-                for (;;) {
-                        if (signal_pending(current))
-                                goto interrupted;
-
-                        /* ask userspace (returns NULL if it waited on a key
-                         * being constructed) */
-                        key = request_key_construction(type, description,
-                                                       callout_info, aux,
-                                                       user, flags);
-                        if (key)
-                                break;
-
-                        /* someone else made the key we want, so we need to
-                         * search again as it might now be available to us */
-                        key_ref = search_process_keyrings(type, description,
-                                                          type->match,
-                                                          current);
-
-                        kdebug("search 2: %p", key_ref);
-
-                        if (!IS_ERR(key_ref)) {
-                                key = key_ref_to_ptr(key_ref);
-                                break;
-                        }
-
-                        if (PTR_ERR(key_ref) != -EAGAIN) {
-                                key = ERR_PTR(PTR_ERR(key_ref));
-                                break;
-                        }
-                }
-
-                key_user_put(user);
-
-                /* link the new key into the appropriate keyring */
-                if (!IS_ERR(key))
-                        request_key_link(key, dest_keyring);
+                key = construct_key_and_link(type, description, callout_info,
+                                             aux, dest_keyring, flags);
         }
 
 error:
         kleave(" = %p", key);
         return key;
+}
 
-nomem:
-        key = ERR_PTR(-ENOMEM);
-        goto error;
-
-interrupted:
-        key_user_put(user);
-        key = ERR_PTR(-EINTR);
-        goto error;
+/*
+ * wait for construction of a key to complete
+ */
+int wait_for_key_construction(struct key *key, bool intr)
+{
+        int ret;
 
-} /* end request_key_and_link() */
+        ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
+                          intr ? key_wait_bit_intr : key_wait_bit,
+                          intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
+        if (ret < 0)
+                return ret;
+        return key_validate(key);
+}
+EXPORT_SYMBOL(wait_for_key_construction);
 
-/*****************************************************************************/
 /*
  * request a key
  * - search the process's keyrings
  * - check the list of keys being created or updated
  * - call out to userspace for a key if supplementary info was provided
+ * - waits uninterruptible for creation to complete
  */
 struct key *request_key(struct key_type *type,
                         const char *description,
                         const char *callout_info)
 {
-        return request_key_and_link(type, description, callout_info, NULL,
-                                    NULL, KEY_ALLOC_IN_QUOTA);
-
-} /* end request_key() */
-
+        struct key *key;
+        int ret;
+
+        key = request_key_and_link(type, description, callout_info, NULL,
+                                   NULL, KEY_ALLOC_IN_QUOTA);
+        if (!IS_ERR(key)) {
+                ret = wait_for_key_construction(key, false);
+                if (ret < 0) {
+                        key_put(key);
+                        return ERR_PTR(ret);
+                }
+        }
+        return key;
+}
 EXPORT_SYMBOL(request_key);
 
-/*****************************************************************************/
 /*
  * request a key with auxiliary data for the upcaller
  * - search the process's keyrings
  * - check the list of keys being created or updated
  * - call out to userspace for a key if supplementary info was provided
+ * - waits uninterruptible for creation to complete
  */
 struct key *request_key_with_auxdata(struct key_type *type,
                                      const char *description,
                                      const char *callout_info,
                                      void *aux)
 {
-        return request_key_and_link(type, description, callout_info, aux,
-                                    NULL, KEY_ALLOC_IN_QUOTA);
+        struct key *key;
+        int ret;
+
+        key = request_key_and_link(type, description, callout_info, aux,
+                                   NULL, KEY_ALLOC_IN_QUOTA);
+        if (!IS_ERR(key)) {
+                ret = wait_for_key_construction(key, false);
+                if (ret < 0) {
+                        key_put(key);
+                        return ERR_PTR(ret);
+                }
+        }
+        return key;
+}
+EXPORT_SYMBOL(request_key_with_auxdata);
 
-} /* end request_key_with_auxdata() */
+/*
+ * request a key (allow async construction)
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if supplementary info was provided
+ */
+struct key *request_key_async(struct key_type *type,
+                              const char *description,
+                              const char *callout_info)
+{
+        return request_key_and_link(type, description, callout_info, NULL,
+                                    NULL, KEY_ALLOC_IN_QUOTA);
+}
+EXPORT_SYMBOL(request_key_async);
 
-EXPORT_SYMBOL(request_key_with_auxdata);
+/*
+ * request a key with auxiliary data for the upcaller (allow async construction)
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if supplementary info was provided
+ */
+struct key *request_key_async_with_auxdata(struct key_type *type,
+                                           const char *description,
+                                           const char *callout_info,
+                                           void *aux)
+{
+        return request_key_and_link(type, description, callout_info, aux,
+                                    NULL, KEY_ALLOC_IN_QUOTA);
+}
+EXPORT_SYMBOL(request_key_async_with_auxdata);