/* user_defined.c: user defined key type * * 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/slab.h> #include <linux/seq_file.h> #include <linux/err.h> #include <keys/user-type.h> #include <linux/uaccess.h> #include "internal.h" static int logon_vet_description(const char *desc); /* * user defined keys take an arbitrary string as the description and an * arbitrary blob of data as the payload */ struct key_type key_type_user = { .name = "user", .preparse = user_preparse, .free_preparse = user_free_preparse, .instantiate = generic_key_instantiate, .update = user_update, .revoke = user_revoke, .destroy = user_destroy, .describe = user_describe, .read = user_read, }; EXPORT_SYMBOL_GPL(key_type_user); /* * This key type is essentially the same as key_type_user, but it does * not define a .read op. This is suitable for storing username and * password pairs in the keyring that you do not want to be readable * from userspace. */ struct key_type key_type_logon = { .name = "logon", .preparse = user_preparse, .free_preparse = user_free_preparse, .instantiate = generic_key_instantiate, .update = user_update, .revoke = user_revoke, .destroy = user_destroy, .describe = user_describe, .vet_description = logon_vet_description, }; EXPORT_SYMBOL_GPL(key_type_logon); /* * Preparse a user defined key payload */ int user_preparse(struct key_preparsed_payload *prep) { struct user_key_payload *upayload; size_t datalen = prep->datalen; if (datalen <= 0 || datalen > 32767 || !prep->data) return -EINVAL; upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); if (!upayload) return -ENOMEM; /* attach the data */ prep->quotalen = datalen; prep->payload.data[0] = upayload; upayload->datalen = datalen; memcpy(upayload->data, prep->data, datalen); return 0; } EXPORT_SYMBOL_GPL(user_preparse); /* * Free a preparse of a user defined key payload */ void user_free_preparse(struct key_preparsed_payload *prep) { kzfree(prep->payload.data[0]); } EXPORT_SYMBOL_GPL(user_free_preparse); static void user_free_payload_rcu(struct rcu_head *head) { struct user_key_payload *payload; payload = container_of(head, struct user_key_payload, rcu); kzfree(payload); } /* * update a user defined key * - the key's semaphore is write-locked */ int user_update(struct key *key, struct key_preparsed_payload *prep) { struct user_key_payload *zap = NULL; int ret; /* check the quota and attach the new data */ ret = key_payload_reserve(key, prep->datalen); if (ret < 0) return ret; /* attach the new data, displacing the old */ key->expiry = prep->expiry; if (key_is_positive(key)) zap = dereference_key_locked(key); rcu_assign_keypointer(key, prep->payload.data[0]); prep->payload.data[0] = NULL; if (zap) call_rcu(&zap->rcu, user_free_payload_rcu); return ret; } EXPORT_SYMBOL_GPL(user_update); /* * dispose of the links from a revoked keyring * - called with the key sem write-locked */ void user_revoke(struct key *key) { struct user_key_payload *upayload = user_key_payload_locked(key); /* clear the quota */ key_payload_reserve(key, 0); if (upayload) { rcu_assign_keypointer(key, NULL); call_rcu(&upayload->rcu, user_free_payload_rcu); } } EXPORT_SYMBOL(user_revoke); /* * dispose of the data dangling from the corpse of a user key */ void user_destroy(struct key *key) { struct user_key_payload *upayload = key->payload.data[0]; kzfree(upayload); } EXPORT_SYMBOL_GPL(user_destroy); /* * describe the user key */ void user_describe(const struct key *key, struct seq_file *m) { seq_puts(m, key->description); if (key_is_positive(key)) seq_printf(m, ": %u", key->datalen); } EXPORT_SYMBOL_GPL(user_describe); /* * read the key data * - the key's semaphore is read-locked */ long user_read(const struct key *key, char __user *buffer, size_t buflen) { const struct user_key_payload *upayload; long ret; upayload = user_key_payload_locked(key); ret = upayload->datalen; /* we can return the data as is */ if (buffer && buflen > 0) { if (buflen > upayload->datalen) buflen = upayload->datalen; if (copy_to_user(buffer, upayload->data, buflen) != 0) ret = -EFAULT; } return ret; } EXPORT_SYMBOL_GPL(user_read); /* Vet the description for a "logon" key */ static int logon_vet_description(const char *desc) { char *p; /* require a "qualified" description string */ p = strchr(desc, ':'); if (!p) return -EINVAL; /* also reject description with ':' as first char */ if (p == desc) return -EINVAL; return 0; }