--- /dev/null
+/* process_keys.c: management of a process's keyrings
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/keyctl.h>
+#include <linux/fs.h>
+#include <linux/err.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+/* session keyring create vs join semaphore */
+static DECLARE_MUTEX(key_session_sem);
+
+/* the root user's tracking struct */
+struct key_user root_key_user = {
+ .usage = ATOMIC_INIT(3),
+ .consq = LIST_HEAD_INIT(root_key_user.consq),
+ .lock = SPIN_LOCK_UNLOCKED,
+ .nkeys = ATOMIC_INIT(2),
+ .nikeys = ATOMIC_INIT(2),
+ .uid = 0,
+};
+
+/* the root user's UID keyring */
+struct key root_user_keyring = {
+ .usage = ATOMIC_INIT(1),
+ .serial = 2,
+ .type = &key_type_keyring,
+ .user = &root_key_user,
+ .lock = RW_LOCK_UNLOCKED,
+ .sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
+ .perm = KEY_USR_ALL,
+ .flags = KEY_FLAG_INSTANTIATED,
+ .description = "_uid.0",
+#ifdef KEY_DEBUGGING
+ .magic = KEY_DEBUG_MAGIC,
+#endif
+};
+
+/* the root user's default session keyring */
+struct key root_session_keyring = {
+ .usage = ATOMIC_INIT(1),
+ .serial = 1,
+ .type = &key_type_keyring,
+ .user = &root_key_user,
+ .lock = RW_LOCK_UNLOCKED,
+ .sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
+ .perm = KEY_USR_ALL,
+ .flags = KEY_FLAG_INSTANTIATED,
+ .description = "_uid_ses.0",
+#ifdef KEY_DEBUGGING
+ .magic = KEY_DEBUG_MAGIC,
+#endif
+};
+
+/*****************************************************************************/
+/*
+ * allocate the keyrings to be associated with a UID
+ */
+int alloc_uid_keyring(struct user_struct *user)
+{
+ struct key *uid_keyring, *session_keyring;
+ char buf[20];
+ int ret;
+
+ /* concoct a default session keyring */
+ sprintf(buf, "_uid_ses.%u", user->uid);
+
+ session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0, NULL);
+ if (IS_ERR(session_keyring)) {
+ ret = PTR_ERR(session_keyring);
+ goto error;
+ }
+
+ /* and a UID specific keyring, pointed to by the default session
+ * keyring */
+ sprintf(buf, "_uid.%u", user->uid);
+
+ uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0,
+ session_keyring);
+ if (IS_ERR(uid_keyring)) {
+ key_put(session_keyring);
+ ret = PTR_ERR(uid_keyring);
+ goto error;
+ }
+
+ /* install the keyrings */
+ user->uid_keyring = uid_keyring;
+ user->session_keyring = session_keyring;
+ ret = 0;
+
+ error:
+ return ret;
+
+} /* end alloc_uid_keyring() */
+
+/*****************************************************************************/
+/*
+ * deal with the UID changing
+ */
+void switch_uid_keyring(struct user_struct *new_user)
+{
+#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);
+
+ key_put(old);
+ }
+#endif
+
+} /* end switch_uid_keyring() */
+
+/*****************************************************************************/
+/*
+ * install a fresh thread keyring, discarding the old one
+ */
+int install_thread_keyring(struct task_struct *tsk)
+{
+ struct key *keyring, *old;
+ char buf[20];
+ int ret;
+
+ sprintf(buf, "_tid.%u", tsk->pid);
+
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto error;
+ }
+
+ task_lock(tsk);
+ old = tsk->thread_keyring;
+ tsk->thread_keyring = keyring;
+ task_unlock(tsk);
+
+ ret = 0;
+
+ key_put(old);
+ error:
+ return ret;
+
+} /* end install_thread_keyring() */
+
+/*****************************************************************************/
+/*
+ * install a fresh process keyring, discarding the old one
+ */
+static int install_process_keyring(struct task_struct *tsk)
+{
+ struct key *keyring, *old;
+ char buf[20];
+ int ret;
+
+ sprintf(buf, "_pid.%u", tsk->tgid);
+
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto error;
+ }
+
+ task_lock(tsk);
+ old = tsk->process_keyring;
+ tsk->process_keyring = keyring;
+ task_unlock(tsk);
+
+ ret = 0;
+
+ key_put(old);
+ error:
+ return ret;
+
+} /* end install_process_keyring() */
+
+/*****************************************************************************/
+/*
+ * install a session keyring, discarding the old one
+ * - if a keyring is not supplied, an empty one is invented
+ */
+static int install_session_keyring(struct task_struct *tsk,
+ struct key *keyring)
+{
+ struct key *old;
+ char buf[20];
+ int ret;
+
+ /* create an empty session keyring */
+ if (!keyring) {
+ sprintf(buf, "_ses.%u", tsk->tgid);
+
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto error;
+ }
+ }
+ else {
+ atomic_inc(&keyring->usage);
+ }
+
+ /* install the keyring */
+ task_lock(tsk);
+ old = tsk->session_keyring;
+ tsk->session_keyring = keyring;
+ task_unlock(tsk);
+
+ ret = 0;
+
+ key_put(old);
+ error:
+ return ret;
+
+} /* end install_session_keyring() */
+
+/*****************************************************************************/
+/*
+ * copy the keys for fork
+ */
+int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
+{
+ int ret = 0;
+
+ key_check(tsk->session_keyring);
+ key_check(tsk->process_keyring);
+ key_check(tsk->thread_keyring);
+
+ if (tsk->session_keyring)
+ atomic_inc(&tsk->session_keyring->usage);
+
+ if (tsk->process_keyring) {
+ if (clone_flags & CLONE_THREAD) {
+ atomic_inc(&tsk->process_keyring->usage);
+ }
+ else {
+ tsk->process_keyring = NULL;
+ ret = install_process_keyring(tsk);
+ }
+ }
+
+ tsk->thread_keyring = NULL;
+ return ret;
+
+} /* end copy_keys() */
+
+/*****************************************************************************/
+/*
+ * dispose of keys upon exit
+ */
+void exit_keys(struct task_struct *tsk)
+{
+ key_put(tsk->session_keyring);
+ key_put(tsk->process_keyring);
+ key_put(tsk->thread_keyring);
+
+} /* end exit_keys() */
+
+/*****************************************************************************/
+/*
+ * deal with execve()
+ */
+int exec_keys(struct task_struct *tsk)
+{
+ struct key *old;
+
+ /* newly exec'd tasks don't get a thread keyring */
+ task_lock(tsk);
+ old = tsk->thread_keyring;
+ tsk->thread_keyring = NULL;
+ task_unlock(tsk);
+
+ key_put(old);
+
+ /* newly exec'd tasks get a fresh process keyring */
+ return install_process_keyring(tsk);
+
+} /* end exec_keys() */
+
+/*****************************************************************************/
+/*
+ * deal with SUID programs
+ * - we might want to make this invent a new session keyring
+ */
+int suid_keys(struct task_struct *tsk)
+{
+ return 0;
+
+} /* end suid_keys() */
+
+/*****************************************************************************/
+/*
+ * the filesystem user ID changed
+ */
+void key_fsuid_changed(struct task_struct *tsk)
+{
+ /* update the ownership of the process keyring */
+ if (tsk->process_keyring) {
+ down_write(&tsk->process_keyring->sem);
+ write_lock(&tsk->process_keyring->lock);
+ tsk->process_keyring->uid = tsk->fsuid;
+ write_unlock(&tsk->process_keyring->lock);
+ up_write(&tsk->process_keyring->sem);
+ }
+
+ /* update the ownership of the thread keyring */
+ if (tsk->thread_keyring) {
+ down_write(&tsk->thread_keyring->sem);
+ write_lock(&tsk->thread_keyring->lock);
+ tsk->thread_keyring->uid = tsk->fsuid;
+ write_unlock(&tsk->thread_keyring->lock);
+ up_write(&tsk->thread_keyring->sem);
+ }
+
+} /* end key_fsuid_changed() */
+
+/*****************************************************************************/
+/*
+ * the filesystem group ID changed
+ */
+void key_fsgid_changed(struct task_struct *tsk)
+{
+ /* update the ownership of the process keyring */
+ if (tsk->process_keyring) {
+ down_write(&tsk->process_keyring->sem);
+ write_lock(&tsk->process_keyring->lock);
+ tsk->process_keyring->gid = tsk->fsgid;
+ write_unlock(&tsk->process_keyring->lock);
+ up_write(&tsk->process_keyring->sem);
+ }
+
+ /* update the ownership of the thread keyring */
+ if (tsk->thread_keyring) {
+ down_write(&tsk->thread_keyring->sem);
+ write_lock(&tsk->thread_keyring->lock);
+ tsk->thread_keyring->gid = tsk->fsgid;
+ write_unlock(&tsk->thread_keyring->lock);
+ up_write(&tsk->thread_keyring->sem);
+ }
+
+} /* end key_fsgid_changed() */
+
+/*****************************************************************************/
+/*
+ * search the process keyrings for the first matching key
+ * - we use the supplied match function to see if the description (or other
+ * feature of interest) matches
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we found only negative matching keys
+ */
+struct key *search_process_keyrings_aux(struct key_type *type,
+ const void *description,
+ key_match_func_t match)
+{
+ struct task_struct *tsk = current;
+ struct key *key, *ret, *err, *session;
+
+ /* 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
+ * none of the keyrings were searchable
+ *
+ * in terms of priority: success > -ENOKEY > -EAGAIN > other error
+ */
+ key = NULL;
+ ret = NULL;
+ err = ERR_PTR(-EAGAIN);
+
+ /* search the thread keyring first */
+ if (tsk->thread_keyring) {
+ key = keyring_search_aux(tsk->thread_keyring, type,
+ description, match);
+ if (!IS_ERR(key))
+ goto found;
+
+ switch (PTR_ERR(key)) {
+ case -EAGAIN: /* no key */
+ if (ret)
+ break;
+ case -ENOKEY: /* negative key */
+ ret = key;
+ break;
+ default:
+ err = key;
+ break;
+ }
+ }
+
+ /* search the process keyring second */
+ if (tsk->process_keyring) {
+ key = keyring_search_aux(tsk->process_keyring, type,
+ description, match);
+ if (!IS_ERR(key))
+ goto found;
+
+ switch (PTR_ERR(key)) {
+ case -EAGAIN: /* no key */
+ if (ret)
+ break;
+ case -ENOKEY: /* negative key */
+ ret = key;
+ break;
+ default:
+ err = key;
+ break;
+ }
+ }
+
+ /* search the session keyring last */
+ session = tsk->session_keyring;
+ if (!session)
+ session = tsk->user->session_keyring;
+
+ key = keyring_search_aux(session, type,
+ description, match);
+ if (!IS_ERR(key))
+ goto found;
+
+ switch (PTR_ERR(key)) {
+ case -EAGAIN: /* no key */
+ if (ret)
+ break;
+ case -ENOKEY: /* negative key */
+ ret = key;
+ break;
+ default:
+ err = key;
+ break;
+ }
+
+ /* no key - decide on the error we're going to go for */
+ key = ret ? ret : err;
+
+ found:
+ return key;
+
+} /* end search_process_keyrings_aux() */
+
+/*****************************************************************************/
+/*
+ * search the process keyrings for the first matching key
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we found only negative matching keys
+ */
+struct key *search_process_keyrings(struct key_type *type,
+ const char *description)
+{
+ return search_process_keyrings_aux(type, description, type->match);
+
+} /* end search_process_keyrings() */
+
+/*****************************************************************************/
+/*
+ * lookup a key given a key ID from userspace with a given permissions mask
+ * - don't create special keyrings unless so requested
+ * - partially constructed keys aren't found unless requested
+ */
+struct key *lookup_user_key(key_serial_t id, int create, int partial,
+ key_perm_t perm)
+{
+ struct task_struct *tsk = current;
+ struct key *key;
+ int ret;
+
+ key = ERR_PTR(-ENOKEY);
+
+ switch (id) {
+ case KEY_SPEC_THREAD_KEYRING:
+ if (!tsk->thread_keyring) {
+ if (!create)
+ goto error;
+
+ ret = install_thread_keyring(tsk);
+ if (ret < 0) {
+ key = ERR_PTR(ret);
+ goto error;
+ }
+ }
+
+ key = tsk->thread_keyring;
+ atomic_inc(&key->usage);
+ break;
+
+ case KEY_SPEC_PROCESS_KEYRING:
+ if (!tsk->process_keyring) {
+ if (!create)
+ goto error;
+
+ ret = install_process_keyring(tsk);
+ if (ret < 0) {
+ key = ERR_PTR(ret);
+ goto error;
+ }
+ }
+
+ key = tsk->process_keyring;
+ atomic_inc(&key->usage);
+ break;
+
+ case KEY_SPEC_SESSION_KEYRING:
+ if (!tsk->session_keyring) {
+ /* always install a session keyring upon access if one
+ * doesn't exist yet */
+ ret = install_session_keyring(
+ tsk, tsk->user->session_keyring);
+ if (ret < 0)
+ goto error;
+ }
+
+ key = tsk->session_keyring;
+ atomic_inc(&key->usage);
+ break;
+
+ case KEY_SPEC_USER_KEYRING:
+ key = tsk->user->uid_keyring;
+ atomic_inc(&key->usage);
+ break;
+
+ case KEY_SPEC_USER_SESSION_KEYRING:
+ key = tsk->user->session_keyring;
+ atomic_inc(&key->usage);
+ break;
+
+ case KEY_SPEC_GROUP_KEYRING:
+ /* group keyrings are not yet supported */
+ key = ERR_PTR(-EINVAL);
+ goto error;
+
+ default:
+ key = ERR_PTR(-EINVAL);
+ if (id < 1)
+ goto error;
+
+ key = key_lookup(id);
+ if (IS_ERR(key))
+ goto error;
+ break;
+ }
+
+ /* check the status and permissions */
+ if (perm) {
+ ret = key_validate(key);
+ if (ret < 0)
+ goto invalid_key;
+ }
+
+ ret = -EIO;
+ if (!partial && !(key->flags & KEY_FLAG_INSTANTIATED))
+ goto invalid_key;
+
+ ret = -EACCES;
+ if (!key_permission(key, perm))
+ goto invalid_key;
+
+ error:
+ return key;
+
+ invalid_key:
+ key_put(key);
+ key = ERR_PTR(ret);
+ goto error;
+
+} /* end lookup_user_key() */
+
+/*****************************************************************************/
+/*
+ * join the named keyring as the session keyring if possible, or attempt to
+ * create a new one of that name if not
+ * - if the name is NULL, an empty anonymous keyring is installed instead
+ * - named session keyring joining is done with a semaphore held
+ */
+long join_session_keyring(const char *name)
+{
+ struct task_struct *tsk = current;
+ struct key *keyring;
+ long ret;
+
+ /* if no name is provided, install an anonymous keyring */
+ if (!name) {
+ ret = install_session_keyring(tsk, NULL);
+ if (ret < 0)
+ goto error;
+
+ ret = tsk->session_keyring->serial;
+ goto error;
+ }
+
+ /* allow the user to join or create a named keyring */
+ down(&key_session_sem);
+
+ /* look for an existing keyring of this name */
+ keyring = find_keyring_by_name(name, 0);
+ if (PTR_ERR(keyring) == -ENOKEY) {
+ /* not found - try and create a new one */
+ keyring = keyring_alloc(name, tsk->uid, tsk->gid, 0, NULL);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto error;
+ }
+ }
+ else if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto error2;
+ }
+
+ /* we've got a keyring - now to install it */
+ ret = install_session_keyring(tsk, keyring);
+ if (ret < 0)
+ goto error2;
+
+ key_put(keyring);
+
+ ret = tsk->session_keyring->serial;
+
+ error2:
+ up(&key_session_sem);
+ error:
+ return ret;
+
+} /* end join_session_keyring() */
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