1 files changed, 665 insertions, 0 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
new file mode 100644
index 000000000000..2eb0e471cd40
--- /dev/null
+++ b/security/keys/process_keys.c
@@ -0,0 +1,665 @@
+/* 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() */
+
+/*****************************************************************************/
+/*
+ * make sure a process keyring is installed
+ */
+static int install_process_keyring(struct task_struct *tsk)
+{
+        unsigned long flags;
+        struct key *keyring;
+        char buf[20];
+        int ret;
+
+        if (!tsk->signal->process_keyring) {
+                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;
+                }
+
+                /* attach or swap keyrings */
+                spin_lock_irqsave(&tsk->sighand->siglock, flags);
+                if (!tsk->signal->process_keyring) {
+                        tsk->signal->process_keyring = keyring;
+                        keyring = NULL;
+                }
+                spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+                key_put(keyring);
+        }
+
+        ret = 0;
+ 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)
+{
+        unsigned long flags;
+        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 */
+        spin_lock_irqsave(&tsk->sighand->siglock, flags);
+        old = tsk->signal->session_keyring;
+        tsk->signal->session_keyring = keyring;
+        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+        ret = 0;
+
+        key_put(old);
+ error:
+        return ret;
+
+} /* end install_session_keyring() */
+
+/*****************************************************************************/
+/*
+ * copy the keys in a thread group for fork without CLONE_THREAD
+ */
+int copy_thread_group_keys(struct task_struct *tsk)
+{
+        unsigned long flags;
+
+        key_check(current->thread_group->session_keyring);
+        key_check(current->thread_group->process_keyring);
+
+        /* no process keyring yet */
+        tsk->signal->process_keyring = NULL;
+
+        /* same session keyring */
+        spin_lock_irqsave(&current->sighand->siglock, flags);
+        tsk->signal->session_keyring =
+                key_get(current->signal->session_keyring);
+        spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+        return 0;
+
+} /* end copy_thread_group_keys() */
+
+/*****************************************************************************/
+/*
+ * copy the keys for fork
+ */
+int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
+{
+        key_check(tsk->thread_keyring);
+
+        /* no thread keyring yet */
+        tsk->thread_keyring = NULL;
+        return 0;
+
+} /* end copy_keys() */
+
+/*****************************************************************************/
+/*
+ * dispose of thread group keys upon thread group destruction
+ */
+void exit_thread_group_keys(struct signal_struct *tg)
+{
+        key_put(tg->session_keyring);
+        key_put(tg->process_keyring);
+
+} /* end exit_thread_group_keys() */
+
+/*****************************************************************************/
+/*
+ * dispose of keys upon thread exit
+ */
+void exit_keys(struct task_struct *tsk)
+{
+        key_put(tsk->thread_keyring);
+
+} /* end exit_keys() */
+
+/*****************************************************************************/
+/*
+ * deal with execve()
+ */
+int exec_keys(struct task_struct *tsk)
+{
+        unsigned long flags;
+        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);
+
+        /* discard the process keyring from a newly exec'd task */
+        spin_lock_irqsave(&tsk->sighand->siglock, flags);
+        old = tsk->signal->process_keyring;
+        tsk->signal->process_keyring = NULL;
+        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+        key_put(old);
+
+        return 0;
+
+} /* 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 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 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;
+        unsigned long flags;
+        struct key *key, *ret, *err, *tmp;
+
+        /* 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->signal->process_keyring) {
+                key = keyring_search_aux(tsk->signal->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 */
+        spin_lock_irqsave(&tsk->sighand->siglock, flags);
+
+        tmp = tsk->signal->session_keyring;
+        if (!tmp)
+                tmp = tsk->user->session_keyring;
+        atomic_inc(&tmp->usage);
+
+        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+        key = keyring_search_aux(tmp, type, description, match);
+        key_put(tmp);
+        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;
+        unsigned long flags;
+        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->signal->process_keyring) {
+                        if (!create)
+                                goto error;
+
+                        ret = install_process_keyring(tsk);
+                        if (ret < 0) {
+                                key = ERR_PTR(ret);
+                                goto error;
+                        }
+                }
+
+                key = tsk->signal->process_keyring;
+                atomic_inc(&key->usage);
+                break;
+
+        case KEY_SPEC_SESSION_KEYRING:
+                if (!tsk->signal->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;
+                }
+
+                spin_lock_irqsave(&tsk->sighand->siglock, flags);
+                key = tsk->signal->session_keyring;
+                atomic_inc(&key->usage);
+                spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+                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;
+        unsigned long flags;
+        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;
+
+                spin_lock_irqsave(&tsk->sighand->siglock, flags);
+                ret = tsk->signal->session_keyring->serial;
+                spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+                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;
+
+        ret = keyring->serial;
+        key_put(keyring);
+
+ error2:
+        up(&key_session_sem);
+ error:
+        return ret;
+
+} /* end join_session_keyring() */