| /* process_keys.c: management of a process's keyrings |
| * |
| * Copyright (C) 2004-5 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 <linux/mutex.h> |
| #include <asm/uaccess.h> |
| #include "internal.h" |
| |
| /* session keyring create vs join semaphore */ |
| static DEFINE_MUTEX(key_session_mutex); |
| |
| /* 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, |
| .sem = __RWSEM_INITIALIZER(root_user_keyring.sem), |
| .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
| .flags = 1 << 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, |
| .sem = __RWSEM_INITIALIZER(root_session_keyring.sem), |
| .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
| .flags = 1 << 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 task_struct *ctx) |
| { |
| 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, ctx, 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, ctx, 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, tsk, 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 |
| */ |
| int install_process_keyring(struct task_struct *tsk) |
| { |
| struct key *keyring; |
| char buf[20]; |
| int ret; |
| |
| might_sleep(); |
| |
| if (!tsk->signal->process_keyring) { |
| sprintf(buf, "_pid.%u", tsk->tgid); |
| |
| keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL); |
| if (IS_ERR(keyring)) { |
| ret = PTR_ERR(keyring); |
| goto error; |
| } |
| |
| /* attach keyring */ |
| spin_lock_irq(&tsk->sighand->siglock); |
| if (!tsk->signal->process_keyring) { |
| tsk->signal->process_keyring = keyring; |
| keyring = NULL; |
| } |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| 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) |
| { |
| struct key *old; |
| char buf[20]; |
| |
| might_sleep(); |
| |
| /* create an empty session keyring */ |
| if (!keyring) { |
| sprintf(buf, "_ses.%u", tsk->tgid); |
| |
| keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL); |
| if (IS_ERR(keyring)) |
| return PTR_ERR(keyring); |
| } |
| else { |
| atomic_inc(&keyring->usage); |
| } |
| |
| /* install the keyring */ |
| spin_lock_irq(&tsk->sighand->siglock); |
| old = tsk->signal->session_keyring; |
| rcu_assign_pointer(tsk->signal->session_keyring, keyring); |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| /* we're using RCU on the pointer, but there's no point synchronising |
| * on it if it didn't previously point to anything */ |
| if (old) { |
| synchronize_rcu(); |
| key_put(old); |
| } |
| |
| return 0; |
| |
| } /* 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) |
| { |
| 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 */ |
| rcu_read_lock(); |
| tsk->signal->session_keyring = |
| key_get(rcu_dereference(current->signal->session_keyring)); |
| rcu_read_unlock(); |
| |
| 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); |
| key_check(tsk->request_key_auth); |
| |
| /* no thread keyring yet */ |
| tsk->thread_keyring = NULL; |
| |
| /* copy the request_key() authorisation for this thread */ |
| key_get(tsk->request_key_auth); |
| |
| 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 per-thread keys upon thread exit |
| */ |
| void exit_keys(struct task_struct *tsk) |
| { |
| key_put(tsk->thread_keyring); |
| key_put(tsk->request_key_auth); |
| |
| } /* 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); |
| |
| /* discard the process keyring from a newly exec'd task */ |
| spin_lock_irq(&tsk->sighand->siglock); |
| old = tsk->signal->process_keyring; |
| tsk->signal->process_keyring = NULL; |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| 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); |
| tsk->thread_keyring->uid = tsk->fsuid; |
| 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); |
| tsk->thread_keyring->gid = tsk->fsgid; |
| 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 |
| */ |
| key_ref_t search_process_keyrings(struct key_type *type, |
| const void *description, |
| key_match_func_t match, |
| struct task_struct *context) |
| { |
| struct request_key_auth *rka; |
| key_ref_t key_ref, ret, err; |
| |
| /* 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_ref = NULL; |
| ret = NULL; |
| err = ERR_PTR(-EAGAIN); |
| |
| /* search the thread keyring first */ |
| if (context->thread_keyring) { |
| key_ref = keyring_search_aux( |
| make_key_ref(context->thread_keyring, 1), |
| context, type, description, match); |
| if (!IS_ERR(key_ref)) |
| goto found; |
| |
| switch (PTR_ERR(key_ref)) { |
| case -EAGAIN: /* no key */ |
| if (ret) |
| break; |
| case -ENOKEY: /* negative key */ |
| ret = key_ref; |
| break; |
| default: |
| err = key_ref; |
| break; |
| } |
| } |
| |
| /* search the process keyring second */ |
| if (context->signal->process_keyring) { |
| key_ref = keyring_search_aux( |
| make_key_ref(context->signal->process_keyring, 1), |
| context, type, description, match); |
| if (!IS_ERR(key_ref)) |
| goto found; |
| |
| switch (PTR_ERR(key_ref)) { |
| case -EAGAIN: /* no key */ |
| if (ret) |
| break; |
| case -ENOKEY: /* negative key */ |
| ret = key_ref; |
| break; |
| default: |
| err = key_ref; |
| break; |
| } |
| } |
| |
| /* search the session keyring */ |
| if (context->signal->session_keyring) { |
| rcu_read_lock(); |
| key_ref = keyring_search_aux( |
| make_key_ref(rcu_dereference( |
| context->signal->session_keyring), |
| 1), |
| context, type, description, match); |
| rcu_read_unlock(); |
| |
| if (!IS_ERR(key_ref)) |
| goto found; |
| |
| switch (PTR_ERR(key_ref)) { |
| case -EAGAIN: /* no key */ |
| if (ret) |
| break; |
| case -ENOKEY: /* negative key */ |
| ret = key_ref; |
| break; |
| default: |
| err = key_ref; |
| break; |
| } |
| } |
| /* or search the user-session keyring */ |
| else { |
| key_ref = keyring_search_aux( |
| make_key_ref(context->user->session_keyring, 1), |
| context, type, description, match); |
| if (!IS_ERR(key_ref)) |
| goto found; |
| |
| switch (PTR_ERR(key_ref)) { |
| case -EAGAIN: /* no key */ |
| if (ret) |
| break; |
| case -ENOKEY: /* negative key */ |
| ret = key_ref; |
| break; |
| default: |
| err = key_ref; |
| break; |
| } |
| } |
| |
| /* if this process has an instantiation authorisation key, then we also |
| * search the keyrings of the process mentioned there |
| * - we don't permit access to request_key auth keys via this method |
| */ |
| if (context->request_key_auth && |
| context == current && |
| type != &key_type_request_key_auth && |
| key_validate(context->request_key_auth) == 0 |
| ) { |
| rka = context->request_key_auth->payload.data; |
| |
| key_ref = search_process_keyrings(type, description, match, |
| rka->context); |
| |
| if (!IS_ERR(key_ref)) |
| goto found; |
| |
| switch (PTR_ERR(key_ref)) { |
| case -EAGAIN: /* no key */ |
| if (ret) |
| break; |
| case -ENOKEY: /* negative key */ |
| ret = key_ref; |
| break; |
| default: |
| err = key_ref; |
| break; |
| } |
| } |
| |
| /* no key - decide on the error we're going to go for */ |
| key_ref = ret ? ret : err; |
| |
| found: |
| return key_ref; |
| |
| } /* end search_process_keyrings() */ |
| |
| /*****************************************************************************/ |
| /* |
| * see if the key we're looking at is the target key |
| */ |
| static int lookup_user_key_possessed(const struct key *key, const void *target) |
| { |
| return key == target; |
| |
| } /* end lookup_user_key_possessed() */ |
| |
| /*****************************************************************************/ |
| /* |
| * 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 |
| */ |
| key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id, |
| int create, int partial, key_perm_t perm) |
| { |
| key_ref_t key_ref, skey_ref; |
| struct key *key; |
| int ret; |
| |
| if (!context) |
| context = current; |
| |
| key_ref = ERR_PTR(-ENOKEY); |
| |
| switch (id) { |
| case KEY_SPEC_THREAD_KEYRING: |
| if (!context->thread_keyring) { |
| if (!create) |
| goto error; |
| |
| ret = install_thread_keyring(context); |
| if (ret < 0) { |
| key = ERR_PTR(ret); |
| goto error; |
| } |
| } |
| |
| key = context->thread_keyring; |
| atomic_inc(&key->usage); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| case KEY_SPEC_PROCESS_KEYRING: |
| if (!context->signal->process_keyring) { |
| if (!create) |
| goto error; |
| |
| ret = install_process_keyring(context); |
| if (ret < 0) { |
| key = ERR_PTR(ret); |
| goto error; |
| } |
| } |
| |
| key = context->signal->process_keyring; |
| atomic_inc(&key->usage); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| case KEY_SPEC_SESSION_KEYRING: |
| if (!context->signal->session_keyring) { |
| /* always install a session keyring upon access if one |
| * doesn't exist yet */ |
| ret = install_session_keyring( |
| context, context->user->session_keyring); |
| if (ret < 0) |
| goto error; |
| } |
| |
| rcu_read_lock(); |
| key = rcu_dereference(context->signal->session_keyring); |
| atomic_inc(&key->usage); |
| rcu_read_unlock(); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| case KEY_SPEC_USER_KEYRING: |
| key = context->user->uid_keyring; |
| atomic_inc(&key->usage); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| case KEY_SPEC_USER_SESSION_KEYRING: |
| key = context->user->session_keyring; |
| atomic_inc(&key->usage); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| case KEY_SPEC_GROUP_KEYRING: |
| /* group keyrings are not yet supported */ |
| key = ERR_PTR(-EINVAL); |
| goto error; |
| |
| case KEY_SPEC_REQKEY_AUTH_KEY: |
| key = context->request_key_auth; |
| if (!key) |
| goto error; |
| |
| atomic_inc(&key->usage); |
| key_ref = make_key_ref(key, 1); |
| break; |
| |
| default: |
| key_ref = ERR_PTR(-EINVAL); |
| if (id < 1) |
| goto error; |
| |
| key = key_lookup(id); |
| if (IS_ERR(key)) { |
| key_ref = ERR_PTR(PTR_ERR(key)); |
| goto error; |
| } |
| |
| key_ref = make_key_ref(key, 0); |
| |
| /* check to see if we possess the key */ |
| skey_ref = search_process_keyrings(key->type, key, |
| lookup_user_key_possessed, |
| current); |
| |
| if (!IS_ERR(skey_ref)) { |
| key_put(key); |
| key_ref = skey_ref; |
| } |
| |
| break; |
| } |
| |
| /* check the status */ |
| if (perm) { |
| ret = key_validate(key); |
| if (ret < 0) |
| goto invalid_key; |
| } |
| |
| ret = -EIO; |
| if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) |
| goto invalid_key; |
| |
| /* check the permissions */ |
| ret = key_task_permission(key_ref, context, perm); |
| if (ret < 0) |
| goto invalid_key; |
| |
| error: |
| return key_ref; |
| |
| invalid_key: |
| key_ref_put(key_ref); |
| key_ref = 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; |
| |
| rcu_read_lock(); |
| ret = rcu_dereference(tsk->signal->session_keyring)->serial; |
| rcu_read_unlock(); |
| goto error; |
| } |
| |
| /* allow the user to join or create a named keyring */ |
| mutex_lock(&key_session_mutex); |
| |
| /* 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, tsk, 0, NULL); |
| if (IS_ERR(keyring)) { |
| ret = PTR_ERR(keyring); |
| goto error2; |
| } |
| } |
| 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: |
| mutex_unlock(&key_session_mutex); |
| error: |
| return ret; |
| |
| } /* end join_session_keyring() */ |