/* Request a key from userspace * * Copyright (C) 2004-2007 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. * * See Documentation/keys-request-key.txt */ #include <linux/module.h> #include <linux/sched.h> #include <linux/kmod.h> #include <linux/err.h> #include <linux/keyctl.h> #include <linux/slab.h> #include "internal.h" #define key_negative_timeout 60 /* default timeout on a negative key's existence */ /* * wait_on_bit() sleep function for uninterruptible waiting */ static int key_wait_bit(void *flags) { schedule(); return 0; } /* * wait_on_bit() sleep function for interruptible waiting */ static int key_wait_bit_intr(void *flags) { schedule(); return signal_pending(current) ? -ERESTARTSYS : 0; } /** * complete_request_key - Complete the construction of a key. * @cons: The key construction record. * @error: The success or failute of the construction. * * Complete the attempt to construct a key. The key will be negated * if an error is indicated. The authorisation key will be revoked * unconditionally. */ void complete_request_key(struct key_construction *cons, int error) { kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error); if (error < 0) key_negate_and_link(cons->key, key_negative_timeout, NULL, cons->authkey); else key_revoke(cons->authkey); key_put(cons->key); key_put(cons->authkey); kfree(cons); } EXPORT_SYMBOL(complete_request_key); /* * Initialise a usermode helper that is going to have a specific session * keyring. * * This is called in context of freshly forked kthread before kernel_execve(), * so we can simply install the desired session_keyring at this point. */ static int umh_keys_init(struct subprocess_info *info) { struct cred *cred = (struct cred*)current_cred(); struct key *keyring = info->data; return install_session_keyring_to_cred(cred, keyring); } /* * Clean up a usermode helper with session keyring. */ static void umh_keys_cleanup(struct subprocess_info *info) { struct key *keyring = info->data; key_put(keyring); } /* * Call a usermode helper with a specific session keyring. */ static int call_usermodehelper_keys(char *path, char **argv, char **envp, struct key *session_keyring, enum umh_wait wait) { gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; struct subprocess_info *info = call_usermodehelper_setup(path, argv, envp, gfp_mask); if (!info) return -ENOMEM; call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup, key_get(session_keyring)); return call_usermodehelper_exec(info, wait); } /* * Request userspace finish the construction of a key * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>" */ static int call_sbin_request_key(struct key_construction *cons, const char *op, void *aux) { const struct cred *cred = current_cred(); key_serial_t prkey, sskey; struct key *key = cons->key, *authkey = cons->authkey, *keyring, *session; char *argv[9], *envp[3], uid_str[12], gid_str[12]; char key_str[12], keyring_str[3][12]; char desc[20]; int ret, i; kenter("{%d},{%d},%s", key->serial, authkey->serial, op); ret = install_user_keyrings(); if (ret < 0) goto error_alloc; /* allocate a new session keyring */ sprintf(desc, "_req.%u", key->serial); cred = get_current_cred(); keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred, KEY_ALLOC_QUOTA_OVERRUN, NULL); put_cred(cred); if (IS_ERR(keyring)) { ret = PTR_ERR(keyring); goto error_alloc; } /* attach the auth key to the session keyring */ ret = key_link(keyring, authkey); if (ret < 0) goto error_link; /* record the UID and GID */ sprintf(uid_str, "%d", cred->fsuid); sprintf(gid_str, "%d", cred->fsgid); /* we say which key is under construction */ sprintf(key_str, "%d", key->serial); /* we specify the process's default keyrings */ sprintf(keyring_str[0], "%d", cred->thread_keyring ? cred->thread_keyring->serial : 0); prkey = 0; if (cred->tgcred->process_keyring) prkey = cred->tgcred->process_keyring->serial; sprintf(keyring_str[1], "%d", prkey); rcu_read_lock(); session = rcu_dereference(cred->tgcred->session_keyring); if (!session) session = cred->user->session_keyring; sskey = session->serial; rcu_read_unlock(); sprintf(keyring_str[2], "%d", sskey); /* set up a minimal environment */ i = 0; envp[i++] = "HOME=/"; envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; envp[i] = NULL; /* set up the argument list */ i = 0; argv[i++] = "/sbin/request-key"; argv[i++] = (char *) op; argv[i++] = key_str; argv[i++] = uid_str; argv[i++] = gid_str; argv[i++] = keyring_str[0]; argv[i++] = keyring_str[1]; argv[i++] = keyring_str[2]; argv[i] = NULL; /* do it */ ret = call_usermodehelper_keys(argv[0], argv, envp, keyring, UMH_WAIT_PROC); kdebug("usermode -> 0x%x", ret); if (ret >= 0) { /* ret is the exit/wait code */ if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) || key_validate(key) < 0) ret = -ENOKEY; else /* ignore any errors from userspace if the key was * instantiated */ ret = 0; } error_link: key_put(keyring); error_alloc: complete_request_key(cons, ret); kleave(" = %d", ret); return ret; } /* * Call out to userspace for key construction. * * Program failure is ignored in favour of key status. */ static int construct_key(struct key *key, const void *callout_info, size_t callout_len, void *aux, struct key *dest_keyring) { struct key_construction *cons; request_key_actor_t actor; struct key *authkey; int ret; kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux); cons = kmalloc(sizeof(*cons), GFP_KERNEL); if (!cons) return -ENOMEM; /* allocate an authorisation key */ authkey = request_key_auth_new(key, callout_info, callout_len, dest_keyring); if (IS_ERR(authkey)) { kfree(cons); ret = PTR_ERR(authkey); authkey = NULL; } else { cons->authkey = key_get(authkey); cons->key = key_get(key); /* make the call */ actor = call_sbin_request_key; if (key->type->request_key) actor = key->type->request_key; ret = actor(cons, "create", aux); /* check that the actor called complete_request_key() prior to * returning an error */ WARN_ON(ret < 0 && !test_bit(KEY_FLAG_REVOKED, &authkey->flags)); key_put(authkey); } kleave(" = %d", ret); return ret; } /* * Get the appropriate destination keyring for the request. * * The keyring selected is returned with an extra reference upon it which the * caller must release. */ static void construct_get_dest_keyring(struct key **_dest_keyring) { struct request_key_auth *rka; const struct cred *cred = current_cred(); struct key *dest_keyring = *_dest_keyring, *authkey; kenter("%p", dest_keyring); /* find the appropriate keyring */ if (dest_keyring) { /* the caller supplied one */ key_get(dest_keyring); } else { /* use a default keyring; falling through the cases until we * find one that we actually have */ switch (cred->jit_keyring) { case KEY_REQKEY_DEFL_DEFAULT: case KEY_REQKEY_DEFL_REQUESTOR_KEYRING: if (cred->request_key_auth) { authkey = cred->request_key_auth; down_read(&authkey->sem); rka = authkey->payload.data; if (!test_bit(KEY_FLAG_REVOKED, &authkey->flags)) dest_keyring = key_get(rka->dest_keyring); up_read(&authkey->sem); if (dest_keyring) break; } case KEY_REQKEY_DEFL_THREAD_KEYRING: dest_keyring = key_get(cred->thread_keyring); if (dest_keyring) break; case KEY_REQKEY_DEFL_PROCESS_KEYRING: dest_keyring = key_get(cred->tgcred->process_keyring); if (dest_keyring) break; case KEY_REQKEY_DEFL_SESSION_KEYRING: rcu_read_lock(); dest_keyring = key_get( rcu_dereference(cred->tgcred->session_keyring)); rcu_read_unlock(); if (dest_keyring) break; case KEY_REQKEY_DEFL_USER_SESSION_KEYRING: dest_keyring = key_get(cred->user->session_keyring); break; case KEY_REQKEY_DEFL_USER_KEYRING: dest_keyring = key_get(cred->user->uid_keyring); break; case KEY_REQKEY_DEFL_GROUP_KEYRING: default: BUG(); } } *_dest_keyring = dest_keyring; kleave(" [dk %d]", key_serial(dest_keyring)); return; } /* * Allocate a new key in under-construction state and attempt to link it in to * the requested keyring. * * May return a key that's already under construction instead if there was a * race between two thread calling request_key(). */ static int construct_alloc_key(struct key_type *type, const char *description, struct key *dest_keyring, unsigned long flags, struct key_user *user, struct key **_key) { const struct cred *cred = current_cred(); unsigned long prealloc; struct key *key; key_ref_t key_ref; int ret; kenter("%s,%s,,,", type->name, description); *_key = NULL; mutex_lock(&user->cons_lock); key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred, KEY_POS_ALL, flags); if (IS_ERR(key)) goto alloc_failed; set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); if (dest_keyring) { ret = __key_link_begin(dest_keyring, type, description, &prealloc); if (ret < 0) goto link_prealloc_failed; } /* attach the key to the destination keyring under lock, but we do need * to do another check just in case someone beat us to it whilst we * waited for locks */ mutex_lock(&key_construction_mutex); key_ref = search_process_keyrings(type, description, type->match, cred); if (!IS_ERR(key_ref)) goto key_already_present; if (dest_keyring) __key_link(dest_keyring, key, &prealloc); mutex_unlock(&key_construction_mutex); if (dest_keyring) __key_link_end(dest_keyring, type, prealloc); mutex_unlock(&user->cons_lock); *_key = key; kleave(" = 0 [%d]", key_serial(key)); return 0; /* the key is now present - we tell the caller that we found it by * returning -EINPROGRESS */ key_already_present: key_put(key); mutex_unlock(&key_construction_mutex); key = key_ref_to_ptr(key_ref); if (dest_keyring) { ret = __key_link_check_live_key(dest_keyring, key); if (ret == 0) __key_link(dest_keyring, key, &prealloc); __key_link_end(dest_keyring, type, prealloc); if (ret < 0) goto link_check_failed; } mutex_unlock(&user->cons_lock); *_key = key; kleave(" = -EINPROGRESS [%d]", key_serial(key)); return -EINPROGRESS; link_check_failed: mutex_unlock(&user->cons_lock); key_put(key); kleave(" = %d [linkcheck]", ret); return ret; link_prealloc_failed: mutex_unlock(&user->cons_lock); kleave(" = %d [prelink]", ret); return ret; alloc_failed: mutex_unlock(&user->cons_lock); kleave(" = %ld", PTR_ERR(key)); return PTR_ERR(key); } /* * Commence key construction. */ static struct key *construct_key_and_link(struct key_type *type, const char *description, const char *callout_info, size_t callout_len, void *aux, struct key *dest_keyring, unsigned long flags) { struct key_user *user; struct key *key; int ret; kenter(""); user = key_user_lookup(current_fsuid(), current_user_ns()); if (!user) return ERR_PTR(-ENOMEM); construct_get_dest_keyring(&dest_keyring); ret = construct_alloc_key(type, description, dest_keyring, flags, user, &key); key_user_put(user); if (ret == 0) { ret = construct_key(key, callout_info, callout_len, aux, dest_keyring); if (ret < 0) { kdebug("cons failed"); goto construction_failed; } } else if (ret == -EINPROGRESS) { ret = 0; } else { key = ERR_PTR(ret); } key_put(dest_keyring); kleave(" = key %d", key_serial(key)); return key; construction_failed: key_negate_and_link(key, key_negative_timeout, NULL, NULL); key_put(key); key_put(dest_keyring); kleave(" = %d", ret); return ERR_PTR(ret); } /** * request_key_and_link - Request a key and cache it in a keyring. * @type: The type of key we want. * @description: The searchable description of the key. * @callout_info: The data to pass to the instantiation upcall (or NULL). * @callout_len: The length of callout_info. * @aux: Auxiliary data for the upcall. * @dest_keyring: Where to cache the key. * @flags: Flags to key_alloc(). * * A key matching the specified criteria is searched for in the process's * keyrings and returned with its usage count incremented if found. Otherwise, * if callout_info is not NULL, a key will be allocated and some service * (probably in userspace) will be asked to instantiate it. * * If successfully found or created, the key will be linked to the destination * keyring if one is provided. * * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT * if insufficient key quota was available to create a new key; or -ENOMEM if * insufficient memory was available. * * If the returned key was created, then it may still be under construction, * and wait_for_key_construction() should be used to wait for that to complete. */ struct key *request_key_and_link(struct key_type *type, const char *description, const void *callout_info, size_t callout_len, void *aux, struct key *dest_keyring, unsigned long flags) { const struct cred *cred = current_cred(); struct key *key; key_ref_t key_ref; int ret; kenter("%s,%s,%p,%zu,%p,%p,%lx", type->name, description, callout_info, callout_len, aux, dest_keyring, flags); /* search all the process keyrings for a key */ key_ref = search_process_keyrings(type, description, type->match, cred); if (!IS_ERR(key_ref)) { key = key_ref_to_ptr(key_ref); if (dest_keyring) { construct_get_dest_keyring(&dest_keyring); ret = key_link(dest_keyring, key); key_put(dest_keyring); if (ret < 0) { key_put(key); key = ERR_PTR(ret); goto error; } } } else if (PTR_ERR(key_ref) != -EAGAIN) { key = ERR_CAST(key_ref); } else { /* the search failed, but the keyrings were searchable, so we * should consult userspace if we can */ key = ERR_PTR(-ENOKEY); if (!callout_info) goto error; key = construct_key_and_link(type, description, callout_info, callout_len, aux, dest_keyring, flags); } error: kleave(" = %p", key); return key; } /** * wait_for_key_construction - Wait for construction of a key to complete * @key: The key being waited for. * @intr: Whether to wait interruptibly. * * Wait for a key to finish being constructed. * * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was * revoked or expired. */ int wait_for_key_construction(struct key *key, bool intr) { int ret; ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT, intr ? key_wait_bit_intr : key_wait_bit, intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE); if (ret < 0) return ret; if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) return key->type_data.reject_error; return key_validate(key); } EXPORT_SYMBOL(wait_for_key_construction); /** * request_key - Request a key and wait for construction * @type: Type of key. * @description: The searchable description of the key. * @callout_info: The data to pass to the instantiation upcall (or NULL). * * As for request_key_and_link() except that it does not add the returned key * to a keyring if found, new keys are always allocated in the user's quota, * the callout_info must be a NUL-terminated string and no auxiliary data can * be passed. * * Furthermore, it then works as wait_for_key_construction() to wait for the * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key(struct key_type *type, const char *description, const char *callout_info) { struct key *key; size_t callout_len = 0; int ret; if (callout_info) callout_len = strlen(callout_info); key = request_key_and_link(type, description, callout_info, callout_len, NULL, NULL, KEY_ALLOC_IN_QUOTA); if (!IS_ERR(key)) { ret = wait_for_key_construction(key, false); if (ret < 0) { key_put(key); return ERR_PTR(ret); } } return key; } EXPORT_SYMBOL(request_key); /** * request_key_with_auxdata - Request a key with auxiliary data for the upcaller * @type: The type of key we want. * @description: The searchable description of the key. * @callout_info: The data to pass to the instantiation upcall (or NULL). * @callout_len: The length of callout_info. * @aux: Auxiliary data for the upcall. * * As for request_key_and_link() except that it does not add the returned key * to a keyring if found and new keys are always allocated in the user's quota. * * Furthermore, it then works as wait_for_key_construction() to wait for the * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key_with_auxdata(struct key_type *type, const char *description, const void *callout_info, size_t callout_len, void *aux) { struct key *key; int ret; key = request_key_and_link(type, description, callout_info, callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA); if (!IS_ERR(key)) { ret = wait_for_key_construction(key, false); if (ret < 0) { key_put(key); return ERR_PTR(ret); } } return key; } EXPORT_SYMBOL(request_key_with_auxdata); /* * request_key_async - Request a key (allow async construction) * @type: Type of key. * @description: The searchable description of the key. * @callout_info: The data to pass to the instantiation upcall (or NULL). * @callout_len: The length of callout_info. * * As for request_key_and_link() except that it does not add the returned key * to a keyring if found, new keys are always allocated in the user's quota and * no auxiliary data can be passed. * * The caller should call wait_for_key_construction() to wait for the * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async(struct key_type *type, const char *description, const void *callout_info, size_t callout_len) { return request_key_and_link(type, description, callout_info, callout_len, NULL, NULL, KEY_ALLOC_IN_QUOTA); } EXPORT_SYMBOL(request_key_async); /* * request a key with auxiliary data for the upcaller (allow async construction) * @type: Type of key. * @description: The searchable description of the key. * @callout_info: The data to pass to the instantiation upcall (or NULL). * @callout_len: The length of callout_info. * @aux: Auxiliary data for the upcall. * * As for request_key_and_link() except that it does not add the returned key * to a keyring if found and new keys are always allocated in the user's quota. * * The caller should call wait_for_key_construction() to wait for the * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async_with_auxdata(struct key_type *type, const char *description, const void *callout_info, size_t callout_len, void *aux) { return request_key_and_link(type, description, callout_info, callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA); } EXPORT_SYMBOL(request_key_async_with_auxdata);