diff options
Diffstat (limited to 'security/keys/process_keys.c')
| -rw-r--r-- | security/keys/process_keys.c | 665 |
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 00000000000..2eb0e471cd4 --- /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(¤t->sighand->siglock, flags); + tsk->signal->session_keyring = + key_get(current->signal->session_keyring); + spin_unlock_irqrestore(¤t->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() */ |