1 files changed, 164 insertions, 169 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 70ee93406f30..df329f684a65 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -42,11 +42,15 @@ struct key_user root_key_user = {
  */
 int install_user_keyrings(void)
 {
-        struct user_struct *user = current->cred->user;
+        struct user_struct *user;
+        const struct cred *cred;
         struct key *uid_keyring, *session_keyring;
         char buf[20];
         int ret;
 
+        cred = current_cred();
+        user = cred->user;
+
         kenter("%p{%u}", user, user->uid);
 
         if (user->uid_keyring) {
@@ -67,7 +71,7 @@ int install_user_keyrings(void)
                 uid_keyring = find_keyring_by_name(buf, true);
                 if (IS_ERR(uid_keyring)) {
                         uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
-                                                    current, KEY_ALLOC_IN_QUOTA,
+                                                    cred, KEY_ALLOC_IN_QUOTA,
                                                     NULL);
                         if (IS_ERR(uid_keyring)) {
                                 ret = PTR_ERR(uid_keyring);
@@ -83,8 +87,7 @@ int install_user_keyrings(void)
                 if (IS_ERR(session_keyring)) {
                         session_keyring =
                                 keyring_alloc(buf, user->uid, (gid_t) -1,
-                                              current, KEY_ALLOC_IN_QUOTA,
-                                              NULL);
+                                              cred, KEY_ALLOC_IN_QUOTA, NULL);
                         if (IS_ERR(session_keyring)) {
                                 ret = PTR_ERR(session_keyring);
                                 goto error_release;
@@ -116,142 +119,128 @@ error:
         return ret;
 }
 
-/*****************************************************************************/
 /*
- * deal with the UID changing
+ * install a fresh thread keyring directly to new credentials
  */
-void switch_uid_keyring(struct user_struct *new_user)
+int install_thread_keyring_to_cred(struct cred *new)
 {
-#if 0 /* do nothing for now */
-        struct key *old;
-
-        /* switch to the new user's session keyring if we were running under
-         * root's default session keyring */
-        if (new_user->uid != 0 &&
-            current->session_keyring == &root_session_keyring
-            ) {
-                atomic_inc(&new_user->session_keyring->usage);
-
-                task_lock(current);
-                old = current->session_keyring;
-                current->session_keyring = new_user->session_keyring;
-                task_unlock(current);
+        struct key *keyring;
 
-                key_put(old);
-        }
-#endif
+        keyring = keyring_alloc("_tid", new->uid, new->gid, new,
+                                KEY_ALLOC_QUOTA_OVERRUN, NULL);
+        if (IS_ERR(keyring))
+                return PTR_ERR(keyring);
 
-} /* end switch_uid_keyring() */
+        new->thread_keyring = keyring;
+        return 0;
+}
 
-/*****************************************************************************/
 /*
  * install a fresh thread keyring, discarding the old one
  */
-int install_thread_keyring(void)
+static int install_thread_keyring(void)
 {
-        struct task_struct *tsk = current;
-        struct key *keyring, *old;
-        char buf[20];
+        struct cred *new;
         int ret;
 
-        sprintf(buf, "_tid.%u", tsk->pid);
+        new = prepare_creds();
+        if (!new)
+                return -ENOMEM;
 
-        keyring = keyring_alloc(buf, tsk->cred->uid, tsk->cred->gid, tsk,
-                                KEY_ALLOC_QUOTA_OVERRUN, NULL);
-        if (IS_ERR(keyring)) {
-                ret = PTR_ERR(keyring);
-                goto error;
+        BUG_ON(new->thread_keyring);
+
+        ret = install_thread_keyring_to_cred(new);
+        if (ret < 0) {
+                abort_creds(new);
+                return ret;
         }
 
-        task_lock(tsk);
-        old = tsk->cred->thread_keyring;
-        tsk->cred->thread_keyring = keyring;
-        task_unlock(tsk);
+        return commit_creds(new);
+}
 
-        ret = 0;
+/*
+ * install a process keyring directly to a credentials struct
+ * - returns -EEXIST if there was already a process keyring, 0 if one installed,
+ *   and other -ve on any other error
+ */
+int install_process_keyring_to_cred(struct cred *new)
+{
+        struct key *keyring;
+        int ret;
 
-        key_put(old);
-error:
+        if (new->tgcred->process_keyring)
+                return -EEXIST;
+
+        keyring = keyring_alloc("_pid", new->uid, new->gid,
+                                new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
+        if (IS_ERR(keyring))
+                return PTR_ERR(keyring);
+
+        spin_lock_irq(&new->tgcred->lock);
+        if (!new->tgcred->process_keyring) {
+                new->tgcred->process_keyring = keyring;
+                keyring = NULL;
+                ret = 0;
+        } else {
+                ret = -EEXIST;
+        }
+        spin_unlock_irq(&new->tgcred->lock);
+        key_put(keyring);
         return ret;
+}
 
-} /* end install_thread_keyring() */
-
-/*****************************************************************************/
 /*
  * make sure a process keyring is installed
+ * - we
  */
-int install_process_keyring(void)
+static int install_process_keyring(void)
 {
-        struct task_struct *tsk = current;
-        struct key *keyring;
-        char buf[20];
+        struct cred *new;
         int ret;
 
-        might_sleep();
-
-        if (!tsk->cred->tgcred->process_keyring) {
-                sprintf(buf, "_pid.%u", tsk->tgid);
-
-                keyring = keyring_alloc(buf, tsk->cred->uid, tsk->cred->gid, tsk,
-                                        KEY_ALLOC_QUOTA_OVERRUN, NULL);
-                if (IS_ERR(keyring)) {
-                        ret = PTR_ERR(keyring);
-                        goto error;
-                }
-
-                /* attach keyring */
-                spin_lock_irq(&tsk->cred->tgcred->lock);
-                if (!tsk->cred->tgcred->process_keyring) {
-                        tsk->cred->tgcred->process_keyring = keyring;
-                        keyring = NULL;
-                }
-                spin_unlock_irq(&tsk->cred->tgcred->lock);
+        new = prepare_creds();
+        if (!new)
+                return -ENOMEM;
 
-                key_put(keyring);
+        ret = install_process_keyring_to_cred(new);
+        if (ret < 0) {
+                abort_creds(new);
+                return ret != -EEXIST ?: 0;
         }
 
-        ret = 0;
-error:
-        return ret;
-
-} /* end install_process_keyring() */
+        return commit_creds(new);
+}
 
-/*****************************************************************************/
 /*
- * install a session keyring, discarding the old one
- * - if a keyring is not supplied, an empty one is invented
+ * install a session keyring directly to a credentials struct
  */
-static int install_session_keyring(struct key *keyring)
+static int install_session_keyring_to_cred(struct cred *cred,
+                                           struct key *keyring)
 {
-        struct task_struct *tsk = current;
         unsigned long flags;
         struct key *old;
-        char buf[20];
 
         might_sleep();
 
         /* create an empty session keyring */
         if (!keyring) {
-                sprintf(buf, "_ses.%u", tsk->tgid);
-
                 flags = KEY_ALLOC_QUOTA_OVERRUN;
-                if (tsk->cred->tgcred->session_keyring)
+                if (cred->tgcred->session_keyring)
                         flags = KEY_ALLOC_IN_QUOTA;
 
-                keyring = keyring_alloc(buf, tsk->cred->uid, tsk->cred->gid,
-                                        tsk, flags, NULL);
+                keyring = keyring_alloc("_ses", cred->uid, cred->gid,
+                                        cred, flags, NULL);
                 if (IS_ERR(keyring))
                         return PTR_ERR(keyring);
-        }
-        else {
+        } else {
                 atomic_inc(&keyring->usage);
         }
 
         /* install the keyring */
-        spin_lock_irq(&tsk->cred->tgcred->lock);
-        old = tsk->cred->tgcred->session_keyring;
-        rcu_assign_pointer(tsk->cred->tgcred->session_keyring, keyring);
-        spin_unlock_irq(&tsk->cred->tgcred->lock);
+        spin_lock_irq(&cred->tgcred->lock);
+        old = cred->tgcred->session_keyring;
+        rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
+        spin_unlock_irq(&cred->tgcred->lock);
 
         /* we're using RCU on the pointer, but there's no point synchronising
          * on it if it didn't previously point to anything */
@@ -261,38 +250,29 @@ static int install_session_keyring(struct key *keyring)
         }
 
         return 0;
+}
 
-} /* end install_session_keyring() */
-
-/*****************************************************************************/
 /*
- * copy the keys for fork
+ * install a session keyring, discarding the old one
+ * - if a keyring is not supplied, an empty one is invented
  */
-int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
+static int install_session_keyring(struct key *keyring)
 {
-        key_check(tsk->cred->thread_keyring);
-        key_check(tsk->cred->request_key_auth);
-
-        /* no thread keyring yet */
-        tsk->cred->thread_keyring = NULL;
-
-        /* copy the request_key() authorisation for this thread */
-        key_get(tsk->cred->request_key_auth);
-
-        return 0;
+        struct cred *new;
+        int ret;
 
-} /* end copy_keys() */
+        new = prepare_creds();
+        if (!new)
+                return -ENOMEM;
 
-/*****************************************************************************/
-/*
- * dispose of per-thread keys upon thread exit
- */
-void exit_keys(struct task_struct *tsk)
-{
-        key_put(tsk->cred->thread_keyring);
-        key_put(tsk->cred->request_key_auth);
+        ret = install_session_keyring_to_cred(new, NULL);
+        if (ret < 0) {
+                abort_creds(new);
+                return ret;
+        }
 
-} /* end exit_keys() */
+        return commit_creds(new);
+}
 
 /*****************************************************************************/
 /*
@@ -300,38 +280,41 @@ void exit_keys(struct task_struct *tsk)
  */
 int exec_keys(struct task_struct *tsk)
 {
-        struct key *old;
+        struct thread_group_cred *tgcred = NULL;
+        struct cred *new;
 
-        /* newly exec'd tasks don't get a thread keyring */
-        task_lock(tsk);
-        old = tsk->cred->thread_keyring;
-        tsk->cred->thread_keyring = NULL;
-        task_unlock(tsk);
+#ifdef CONFIG_KEYS
+        tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
+        if (!tgcred)
+                return -ENOMEM;
+#endif
 
-        key_put(old);
+        new = prepare_creds();
+        if (new < 0)
+                return -ENOMEM;
 
-        /* discard the process keyring from a newly exec'd task */
-        spin_lock_irq(&tsk->cred->tgcred->lock);
-        old = tsk->cred->tgcred->process_keyring;
-        tsk->cred->tgcred->process_keyring = NULL;
-        spin_unlock_irq(&tsk->cred->tgcred->lock);
+        /* newly exec'd tasks don't get a thread keyring */
+        key_put(new->thread_keyring);
+        new->thread_keyring = NULL;
 
-        key_put(old);
+        /* create a new per-thread-group creds for all this set of threads to
+         * share */
+        memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
 
-        return 0;
+        atomic_set(&tgcred->usage, 1);
+        spin_lock_init(&tgcred->lock);
 
-} /* end exec_keys() */
+        /* inherit the session keyring; new process keyring */
+        key_get(tgcred->session_keyring);
+        tgcred->process_keyring = NULL;
 
-/*****************************************************************************/
-/*
- * deal with SUID programs
- * - we might want to make this invent a new session keyring
- */
-int suid_keys(struct task_struct *tsk)
-{
+        release_tgcred(new);
+        new->tgcred = tgcred;
+
+        commit_creds(new);
         return 0;
 
-} /* end suid_keys() */
+} /* end exec_keys() */
 
 /*****************************************************************************/
 /*
@@ -376,16 +359,13 @@ void key_fsgid_changed(struct task_struct *tsk)
 key_ref_t search_process_keyrings(struct key_type *type,
                                   const void *description,
                                   key_match_func_t match,
-                                  struct task_struct *context)
+                                  const struct cred *cred)
 {
         struct request_key_auth *rka;
-        struct cred *cred;
         key_ref_t key_ref, ret, err;
 
         might_sleep();
 
-        cred = get_task_cred(context);
-
         /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
          * searchable, but we failed to find a key or we found a negative key;
          * otherwise we want to return a sample error (probably -EACCES) if
@@ -401,7 +381,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
         if (cred->thread_keyring) {
                 key_ref = keyring_search_aux(
                         make_key_ref(cred->thread_keyring, 1),
-                        context, type, description, match);
+                        cred, type, description, match);
                 if (!IS_ERR(key_ref))
                         goto found;
 
@@ -422,7 +402,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
         if (cred->tgcred->process_keyring) {
                 key_ref = keyring_search_aux(
                         make_key_ref(cred->tgcred->process_keyring, 1),
-                        context, type, description, match);
+                        cred, type, description, match);
                 if (!IS_ERR(key_ref))
                         goto found;
 
@@ -446,7 +426,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
                         make_key_ref(rcu_dereference(
                                              cred->tgcred->session_keyring),
                                      1),
-                        context, type, description, match);
+                        cred, type, description, match);
                 rcu_read_unlock();
 
                 if (!IS_ERR(key_ref))
@@ -468,7 +448,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
         else if (cred->user->session_keyring) {
                 key_ref = keyring_search_aux(
                         make_key_ref(cred->user->session_keyring, 1),
-                        context, type, description, match);
+                        cred, type, description, match);
                 if (!IS_ERR(key_ref))
                         goto found;
 
@@ -490,7 +470,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
          * - we don't permit access to request_key auth keys via this method
          */
         if (cred->request_key_auth &&
-            context == current &&
+            cred == current_cred() &&
             type != &key_type_request_key_auth
             ) {
                 /* defend against the auth key being revoked */
@@ -500,7 +480,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
                         rka = cred->request_key_auth->payload.data;
 
                         key_ref = search_process_keyrings(type, description,
-                                                          match, rka->context);
+                                                          match, rka->cred);
 
                         up_read(&cred->request_key_auth->sem);
 
@@ -527,7 +507,6 @@ key_ref_t search_process_keyrings(struct key_type *type,
         key_ref = ret ? ret : err;
 
 found:
-        put_cred(cred);
         return key_ref;
 
 } /* end search_process_keyrings() */
@@ -552,8 +531,7 @@ key_ref_t lookup_user_key(key_serial_t id, int create, int partial,
                           key_perm_t perm)
 {
         struct request_key_auth *rka;
-        struct task_struct *t = current;
-        struct cred *cred;
+        const struct cred *cred;
         struct key *key;
         key_ref_t key_ref, skey_ref;
         int ret;
@@ -608,6 +586,7 @@ try_again:
                                 goto error;
                         ret = install_session_keyring(
                                 cred->user->session_keyring);
+
                         if (ret < 0)
                                 goto error;
                         goto reget_creds;
@@ -693,7 +672,7 @@ try_again:
                 /* check to see if we possess the key */
                 skey_ref = search_process_keyrings(key->type, key,
                                                    lookup_user_key_possessed,
-                                                   current);
+                                                   cred);
 
                 if (!IS_ERR(skey_ref)) {
                         key_put(key);
@@ -725,7 +704,7 @@ try_again:
                 goto invalid_key;
 
         /* check the permissions */
-        ret = key_task_permission(key_ref, t, perm);
+        ret = key_task_permission(key_ref, cred, perm);
         if (ret < 0)
                 goto invalid_key;
 
@@ -755,21 +734,33 @@ reget_creds:
  */
 long join_session_keyring(const char *name)
 {
-        struct task_struct *tsk = current;
-        struct cred *cred = current->cred;
+        const struct cred *old;
+        struct cred *new;
         struct key *keyring;
-        long ret;
+        long ret, serial;
+
+        /* only permit this if there's a single thread in the thread group -
+         * this avoids us having to adjust the creds on all threads and risking
+         * ENOMEM */
+        if (!is_single_threaded(current))
+                return -EMLINK;
+
+        new = prepare_creds();
+        if (!new)
+                return -ENOMEM;
+        old = current_cred();
 
         /* if no name is provided, install an anonymous keyring */
         if (!name) {
-                ret = install_session_keyring(NULL);
+                ret = install_session_keyring_to_cred(new, NULL);
                 if (ret < 0)
                         goto error;
 
-                rcu_read_lock();
-                ret = rcu_dereference(cred->tgcred->session_keyring)->serial;
-                rcu_read_unlock();
-                goto error;
+                serial = new->tgcred->session_keyring->serial;
+                ret = commit_creds(new);
+                if (ret == 0)
+                        ret = serial;
+                goto okay;
         }
 
         /* allow the user to join or create a named keyring */
@@ -779,29 +770,33 @@ long join_session_keyring(const char *name)
         keyring = find_keyring_by_name(name, false);
         if (PTR_ERR(keyring) == -ENOKEY) {
                 /* not found - try and create a new one */
-                keyring = keyring_alloc(name, cred->uid, cred->gid, tsk,
+                keyring = keyring_alloc(name, old->uid, old->gid, old,
                                         KEY_ALLOC_IN_QUOTA, NULL);
                 if (IS_ERR(keyring)) {
                         ret = PTR_ERR(keyring);
                         goto error2;
                 }
-        }
-        else if (IS_ERR(keyring)) {
+        } else if (IS_ERR(keyring)) {
                 ret = PTR_ERR(keyring);
                 goto error2;
         }
 
         /* we've got a keyring - now to install it */
-        ret = install_session_keyring(keyring);
+        ret = install_session_keyring_to_cred(new, keyring);
         if (ret < 0)
                 goto error2;
 
+        commit_creds(new);
+        mutex_unlock(&key_session_mutex);
+
         ret = keyring->serial;
         key_put(keyring);
+okay:
+        return ret;
 
 error2:
         mutex_unlock(&key_session_mutex);
 error:
+        abort_creds(new);
         return ret;
-
-} /* end join_session_keyring() */
+}