/* 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/sched.h> #include <linux/slab.h> #include <linux/seq_file.h> #include <linux/err.h> #include <keys/user-type.h> #include <asm/uaccess.h> #include "internal.h" /* * 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", .instantiate = user_instantiate, .update = user_update, .match = user_match, .revoke = user_revoke, .destroy = user_destroy, .describe = user_describe, .read = user_read, }; EXPORT_SYMBOL_GPL(key_type_user); /*****************************************************************************/ /* * instantiate a user defined key */ int user_instantiate(struct key *key, const void *data, size_t datalen) { struct user_key_payload *upayload; int ret; ret = -EINVAL; if (datalen <= 0 || datalen > 32767 || !data) goto error; ret = key_payload_reserve(key, datalen); if (ret < 0) goto error; ret = -ENOMEM; upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); if (!upayload) goto error; /* attach the data */ upayload->datalen = datalen; memcpy(upayload->data, data, datalen); rcu_assign_pointer(key->payload.data, upayload); ret = 0; error: return ret; } /* end user_instantiate() */ EXPORT_SYMBOL_GPL(user_instantiate); /*****************************************************************************/ /* * dispose of the old data from an updated user defined key */ static void user_update_rcu_disposal(struct rcu_head *rcu) { struct user_key_payload *upayload; upayload = container_of(rcu, struct user_key_payload, rcu); kfree(upayload); } /* end user_update_rcu_disposal() */ /*****************************************************************************/ /* * update a user defined key * - the key's semaphore is write-locked */ int user_update(struct key *key, const void *data, size_t datalen) { struct user_key_payload *upayload, *zap; int ret; ret = -EINVAL; if (datalen <= 0 || datalen > 32767 || !data) goto error; /* construct a replacement payload */ ret = -ENOMEM; upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); if (!upayload) goto error; upayload->datalen = datalen; memcpy(upayload->data, data, datalen); /* check the quota and attach the new data */ zap = upayload; ret = key_payload_reserve(key, datalen); if (ret == 0) { /* attach the new data, displacing the old */ zap = key->payload.data; rcu_assign_pointer(key->payload.data, upayload); key->expiry = 0; } call_rcu(&zap->rcu, user_update_rcu_disposal); error: return ret; } /* end user_update() */ EXPORT_SYMBOL_GPL(user_update); /*****************************************************************************/ /* * match users on their name */ int user_match(const struct key *key, const void *description) { return strcmp(key->description, description) == 0; } /* end user_match() */ EXPORT_SYMBOL_GPL(user_match); /*****************************************************************************/ /* * 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 = key->payload.data; /* clear the quota */ key_payload_reserve(key, 0); if (upayload) { rcu_assign_pointer(key->payload.data, NULL); call_rcu(&upayload->rcu, user_update_rcu_disposal); } } /* end user_revoke() */ 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; kfree(upayload); } /* end user_destroy() */ 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); seq_printf(m, ": %u", key->datalen); } /* end user_describe() */ 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) { struct user_key_payload *upayload; long ret; upayload = rcu_dereference(key->payload.data); 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; } /* end user_read() */ EXPORT_SYMBOL_GPL(user_read);