1/*
  2 * Generic RPC credential
  3 *
  4 * Copyright (C) 2008, Trond Myklebust <Trond.Myklebust@netapp.com>
  5 */
  6
  7#include <linux/err.h>
  8#include <linux/slab.h>
  9#include <linux/types.h>
 10#include <linux/module.h>
 11#include <linux/sched.h>
 12#include <linux/sunrpc/auth.h>
 13#include <linux/sunrpc/clnt.h>
 14#include <linux/sunrpc/debug.h>
 15#include <linux/sunrpc/sched.h>
 16
 17#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 18# define RPCDBG_FACILITY	RPCDBG_AUTH
 19#endif
 20
 21#define RPC_MACHINE_CRED_USERID		GLOBAL_ROOT_UID
 22#define RPC_MACHINE_CRED_GROUPID	GLOBAL_ROOT_GID
 23
 24struct generic_cred {
 25	struct rpc_cred gc_base;
 26	struct auth_cred acred;
 27};
 28
 29static struct rpc_auth generic_auth;
 30static const struct rpc_credops generic_credops;
 31
 32/*
 33 * Public call interface
 34 */
 35struct rpc_cred *rpc_lookup_cred(void)
 36{
 37	return rpcauth_lookupcred(&generic_auth, 0);
 38}
 39EXPORT_SYMBOL_GPL(rpc_lookup_cred);
 40
 41struct rpc_cred *rpc_lookup_cred_nonblock(void)
 42{
 43	return rpcauth_lookupcred(&generic_auth, RPCAUTH_LOOKUP_RCU);
 44}
 45EXPORT_SYMBOL_GPL(rpc_lookup_cred_nonblock);
 46
 47/*
 48 * Public call interface for looking up machine creds.
 49 */
 50struct rpc_cred *rpc_lookup_machine_cred(const char *service_name)
 51{
 52	struct auth_cred acred = {
 53		.uid = RPC_MACHINE_CRED_USERID,
 54		.gid = RPC_MACHINE_CRED_GROUPID,
 55		.principal = service_name,
 56		.machine_cred = 1,
 57	};
 58
 59	dprintk("RPC:       looking up machine cred for service %s\n",
 60			service_name);
 61	return generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
 62}
 63EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);
 64
 65static struct rpc_cred *generic_bind_cred(struct rpc_task *task,
 66		struct rpc_cred *cred, int lookupflags)
 67{
 68	struct rpc_auth *auth = task->tk_client->cl_auth;
 69	struct auth_cred *acred = &container_of(cred, struct generic_cred, gc_base)->acred;
 70
 71	return auth->au_ops->lookup_cred(auth, acred, lookupflags);
 72}
 73
 74/*
 75 * Lookup generic creds for current process
 76 */
 77static struct rpc_cred *
 78generic_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
 79{
 80	return rpcauth_lookup_credcache(&generic_auth, acred, flags);
 81}
 82
 83static struct rpc_cred *
 84generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
 85{
 86	struct generic_cred *gcred;
 87
 88	gcred = kmalloc(sizeof(*gcred), GFP_KERNEL);
 89	if (gcred == NULL)
 90		return ERR_PTR(-ENOMEM);
 91
 92	rpcauth_init_cred(&gcred->gc_base, acred, &generic_auth, &generic_credops);
 93	gcred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
 94
 95	gcred->acred.uid = acred->uid;
 96	gcred->acred.gid = acred->gid;
 97	gcred->acred.group_info = acred->group_info;
 98	gcred->acred.ac_flags = 0;
 99	if (gcred->acred.group_info != NULL)
100		get_group_info(gcred->acred.group_info);
101	gcred->acred.machine_cred = acred->machine_cred;
102	gcred->acred.principal = acred->principal;
103
104	dprintk("RPC:       allocated %s cred %p for uid %d gid %d\n",
105			gcred->acred.machine_cred ? "machine" : "generic",
106			gcred,
107			from_kuid(&init_user_ns, acred->uid),
108			from_kgid(&init_user_ns, acred->gid));
109	return &gcred->gc_base;
110}
111
112static void
113generic_free_cred(struct rpc_cred *cred)
114{
115	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
116
117	dprintk("RPC:       generic_free_cred %p\n", gcred);
118	if (gcred->acred.group_info != NULL)
119		put_group_info(gcred->acred.group_info);
120	kfree(gcred);
121}
122
123static void
124generic_free_cred_callback(struct rcu_head *head)
125{
126	struct rpc_cred *cred = container_of(head, struct rpc_cred, cr_rcu);
127	generic_free_cred(cred);
128}
129
130static void
131generic_destroy_cred(struct rpc_cred *cred)
132{
133	call_rcu(&cred->cr_rcu, generic_free_cred_callback);
134}
135
136static int
137machine_cred_match(struct auth_cred *acred, struct generic_cred *gcred, int flags)
138{
139	if (!gcred->acred.machine_cred ||
140	    gcred->acred.principal != acred->principal ||
141	    !uid_eq(gcred->acred.uid, acred->uid) ||
142	    !gid_eq(gcred->acred.gid, acred->gid))
143		return 0;
144	return 1;
145}
146
147/*
148 * Match credentials against current process creds.
149 */
150static int
151generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
152{
153	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
154	int i;
155
156	if (acred->machine_cred)
157		return machine_cred_match(acred, gcred, flags);
158
159	if (!uid_eq(gcred->acred.uid, acred->uid) ||
160	    !gid_eq(gcred->acred.gid, acred->gid) ||
161	    gcred->acred.machine_cred != 0)
162		goto out_nomatch;
163
164	/* Optimisation in the case where pointers are identical... */
165	if (gcred->acred.group_info == acred->group_info)
166		goto out_match;
167
168	/* Slow path... */
169	if (gcred->acred.group_info->ngroups != acred->group_info->ngroups)
170		goto out_nomatch;
171	for (i = 0; i < gcred->acred.group_info->ngroups; i++) {
172		if (!gid_eq(GROUP_AT(gcred->acred.group_info, i),
173				GROUP_AT(acred->group_info, i)))
174			goto out_nomatch;
175	}
176out_match:
177	return 1;
178out_nomatch:
179	return 0;
180}
181
182int __init rpc_init_generic_auth(void)
183{
184	return rpcauth_init_credcache(&generic_auth);
185}
186
187void rpc_destroy_generic_auth(void)
188{
189	rpcauth_destroy_credcache(&generic_auth);
190}
191
192/*
193 * Test the the current time (now) against the underlying credential key expiry
194 * minus a timeout and setup notification.
195 *
196 * The normal case:
197 * If 'now' is before the key expiry minus RPC_KEY_EXPIRE_TIMEO, set
198 * the RPC_CRED_NOTIFY_TIMEOUT flag to setup the underlying credential
199 * rpc_credops crmatch routine to notify this generic cred when it's key
200 * expiration is within RPC_KEY_EXPIRE_TIMEO, and return 0.
201 *
202 * The error case:
203 * If the underlying cred lookup fails, return -EACCES.
204 *
205 * The 'almost' error case:
206 * If 'now' is within key expiry minus RPC_KEY_EXPIRE_TIMEO, but not within
207 * key expiry minus RPC_KEY_EXPIRE_FAIL, set the RPC_CRED_EXPIRE_SOON bit
208 * on the acred ac_flags and return 0.
209 */
210static int
211generic_key_timeout(struct rpc_auth *auth, struct rpc_cred *cred)
212{
213	struct auth_cred *acred = &container_of(cred, struct generic_cred,
214						gc_base)->acred;
215	struct rpc_cred *tcred;
216	int ret = 0;
217
218
219	/* Fast track for non crkey_timeout (no key) underlying credentials */
220	if (test_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags))
221		return 0;
222
223	/* Fast track for the normal case */
224	if (test_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags))
225		return 0;
226
227	/* lookup_cred either returns a valid referenced rpc_cred, or PTR_ERR */
228	tcred = auth->au_ops->lookup_cred(auth, acred, 0);
229	if (IS_ERR(tcred))
230		return -EACCES;
231
232	if (!tcred->cr_ops->crkey_timeout) {
233		set_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags);
234		ret = 0;
235		goto out_put;
236	}
237
238	/* Test for the almost error case */
239	ret = tcred->cr_ops->crkey_timeout(tcred);
240	if (ret != 0) {
241		set_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
242		ret = 0;
243	} else {
244		/* In case underlying cred key has been reset */
245		if (test_and_clear_bit(RPC_CRED_KEY_EXPIRE_SOON,
246					&acred->ac_flags))
247			dprintk("RPC:        UID %d Credential key reset\n",
248				from_kuid(&init_user_ns, tcred->cr_uid));
249		/* set up fasttrack for the normal case */
250		set_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags);
251	}
252
253out_put:
254	put_rpccred(tcred);
255	return ret;
256}
257
258static const struct rpc_authops generic_auth_ops = {
259	.owner = THIS_MODULE,
260	.au_name = "Generic",
261	.lookup_cred = generic_lookup_cred,
262	.crcreate = generic_create_cred,
263	.key_timeout = generic_key_timeout,
264};
265
266static struct rpc_auth generic_auth = {
267	.au_ops = &generic_auth_ops,
268	.au_count = ATOMIC_INIT(0),
269};
270
271static bool generic_key_to_expire(struct rpc_cred *cred)
272{
273	struct auth_cred *acred = &container_of(cred, struct generic_cred,
274						gc_base)->acred;
275	bool ret;
276
277	get_rpccred(cred);
278	ret = test_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
279	put_rpccred(cred);
280
281	return ret;
282}
283
284static const struct rpc_credops generic_credops = {
285	.cr_name = "Generic cred",
286	.crdestroy = generic_destroy_cred,
287	.crbind = generic_bind_cred,
288	.crmatch = generic_match,
289	.crkey_to_expire = generic_key_to_expire,
290};