xref: /openbmc/linux/net/sunrpc/svcauth.c (revision 78c542f9)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/net/sunrpc/svcauth.c
4  *
5  * The generic interface for RPC authentication on the server side.
6  *
7  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
8  *
9  * CHANGES
10  * 19-Apr-2000 Chris Evans      - Security fix
11  */
12 
13 #include <linux/types.h>
14 #include <linux/module.h>
15 #include <linux/sunrpc/types.h>
16 #include <linux/sunrpc/xdr.h>
17 #include <linux/sunrpc/svcsock.h>
18 #include <linux/sunrpc/svcauth.h>
19 #include <linux/err.h>
20 #include <linux/hash.h>
21 
22 #include <trace/events/sunrpc.h>
23 
24 #include "sunrpc.h"
25 
26 #define RPCDBG_FACILITY	RPCDBG_AUTH
27 
28 
29 /*
30  * Table of authenticators
31  */
32 extern struct auth_ops svcauth_null;
33 extern struct auth_ops svcauth_unix;
34 extern struct auth_ops svcauth_tls;
35 
36 static struct auth_ops __rcu *authtab[RPC_AUTH_MAXFLAVOR] = {
37 	[RPC_AUTH_NULL] = (struct auth_ops __force __rcu *)&svcauth_null,
38 	[RPC_AUTH_UNIX] = (struct auth_ops __force __rcu *)&svcauth_unix,
39 	[RPC_AUTH_TLS]  = (struct auth_ops __force __rcu *)&svcauth_tls,
40 };
41 
42 static struct auth_ops *
svc_get_auth_ops(rpc_authflavor_t flavor)43 svc_get_auth_ops(rpc_authflavor_t flavor)
44 {
45 	struct auth_ops		*aops;
46 
47 	if (flavor >= RPC_AUTH_MAXFLAVOR)
48 		return NULL;
49 	rcu_read_lock();
50 	aops = rcu_dereference(authtab[flavor]);
51 	if (aops != NULL && !try_module_get(aops->owner))
52 		aops = NULL;
53 	rcu_read_unlock();
54 	return aops;
55 }
56 
57 static void
svc_put_auth_ops(struct auth_ops * aops)58 svc_put_auth_ops(struct auth_ops *aops)
59 {
60 	module_put(aops->owner);
61 }
62 
63 /**
64  * svc_authenticate - Initialize an outgoing credential
65  * @rqstp: RPC execution context
66  *
67  * Return values:
68  *   %SVC_OK: XDR encoding of the result can begin
69  *   %SVC_DENIED: Credential or verifier is not valid
70  *   %SVC_GARBAGE: Failed to decode credential or verifier
71  *   %SVC_COMPLETE: GSS context lifetime event; no further action
72  *   %SVC_DROP: Drop this request; no further action
73  *   %SVC_CLOSE: Like drop, but also close transport connection
74  */
svc_authenticate(struct svc_rqst * rqstp)75 enum svc_auth_status svc_authenticate(struct svc_rqst *rqstp)
76 {
77 	struct auth_ops *aops;
78 	u32 flavor;
79 
80 	rqstp->rq_auth_stat = rpc_auth_ok;
81 
82 	/*
83 	 * Decode the Call credential's flavor field. The credential's
84 	 * body field is decoded in the chosen ->accept method below.
85 	 */
86 	if (xdr_stream_decode_u32(&rqstp->rq_arg_stream, &flavor) < 0)
87 		return SVC_GARBAGE;
88 
89 	aops = svc_get_auth_ops(flavor);
90 	if (aops == NULL) {
91 		rqstp->rq_auth_stat = rpc_autherr_badcred;
92 		return SVC_DENIED;
93 	}
94 
95 	rqstp->rq_auth_slack = 0;
96 	init_svc_cred(&rqstp->rq_cred);
97 
98 	rqstp->rq_authop = aops;
99 	return aops->accept(rqstp);
100 }
101 EXPORT_SYMBOL_GPL(svc_authenticate);
102 
103 /**
104  * svc_set_client - Assign an appropriate 'auth_domain' as the client
105  * @rqstp: RPC execution context
106  *
107  * Return values:
108  *   %SVC_OK: Client was found and assigned
109  *   %SVC_DENY: Client was explicitly denied
110  *   %SVC_DROP: Ignore this request
111  *   %SVC_CLOSE: Ignore this request and close the connection
112  */
svc_set_client(struct svc_rqst * rqstp)113 enum svc_auth_status svc_set_client(struct svc_rqst *rqstp)
114 {
115 	rqstp->rq_client = NULL;
116 	return rqstp->rq_authop->set_client(rqstp);
117 }
118 EXPORT_SYMBOL_GPL(svc_set_client);
119 
120 /**
121  * svc_authorise - Finalize credentials/verifier and release resources
122  * @rqstp: RPC execution context
123  *
124  * Returns zero on success, or a negative errno.
125  */
svc_authorise(struct svc_rqst * rqstp)126 int svc_authorise(struct svc_rqst *rqstp)
127 {
128 	struct auth_ops *aops = rqstp->rq_authop;
129 	int rv = 0;
130 
131 	rqstp->rq_authop = NULL;
132 
133 	if (aops) {
134 		rv = aops->release(rqstp);
135 		svc_put_auth_ops(aops);
136 	}
137 	return rv;
138 }
139 
140 int
svc_auth_register(rpc_authflavor_t flavor,struct auth_ops * aops)141 svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
142 {
143 	struct auth_ops *old;
144 	int rv = -EINVAL;
145 
146 	if (flavor < RPC_AUTH_MAXFLAVOR) {
147 		old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops);
148 		if (old == NULL || old == aops)
149 			rv = 0;
150 	}
151 	return rv;
152 }
153 EXPORT_SYMBOL_GPL(svc_auth_register);
154 
155 void
svc_auth_unregister(rpc_authflavor_t flavor)156 svc_auth_unregister(rpc_authflavor_t flavor)
157 {
158 	if (flavor < RPC_AUTH_MAXFLAVOR)
159 		rcu_assign_pointer(authtab[flavor], NULL);
160 }
161 EXPORT_SYMBOL_GPL(svc_auth_unregister);
162 
163 /**************************************************
164  * 'auth_domains' are stored in a hash table indexed by name.
165  * When the last reference to an 'auth_domain' is dropped,
166  * the object is unhashed and freed.
167  * If auth_domain_lookup fails to find an entry, it will return
168  * it's second argument 'new'.  If this is non-null, it will
169  * have been atomically linked into the table.
170  */
171 
172 #define	DN_HASHBITS	6
173 #define	DN_HASHMAX	(1<<DN_HASHBITS)
174 
175 static struct hlist_head	auth_domain_table[DN_HASHMAX];
176 static DEFINE_SPINLOCK(auth_domain_lock);
177 
auth_domain_release(struct kref * kref)178 static void auth_domain_release(struct kref *kref)
179 	__releases(&auth_domain_lock)
180 {
181 	struct auth_domain *dom = container_of(kref, struct auth_domain, ref);
182 
183 	hlist_del_rcu(&dom->hash);
184 	dom->flavour->domain_release(dom);
185 	spin_unlock(&auth_domain_lock);
186 }
187 
auth_domain_put(struct auth_domain * dom)188 void auth_domain_put(struct auth_domain *dom)
189 {
190 	kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock);
191 }
192 EXPORT_SYMBOL_GPL(auth_domain_put);
193 
194 struct auth_domain *
auth_domain_lookup(char * name,struct auth_domain * new)195 auth_domain_lookup(char *name, struct auth_domain *new)
196 {
197 	struct auth_domain *hp;
198 	struct hlist_head *head;
199 
200 	head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
201 
202 	spin_lock(&auth_domain_lock);
203 
204 	hlist_for_each_entry(hp, head, hash) {
205 		if (strcmp(hp->name, name)==0) {
206 			kref_get(&hp->ref);
207 			spin_unlock(&auth_domain_lock);
208 			return hp;
209 		}
210 	}
211 	if (new)
212 		hlist_add_head_rcu(&new->hash, head);
213 	spin_unlock(&auth_domain_lock);
214 	return new;
215 }
216 EXPORT_SYMBOL_GPL(auth_domain_lookup);
217 
auth_domain_find(char * name)218 struct auth_domain *auth_domain_find(char *name)
219 {
220 	struct auth_domain *hp;
221 	struct hlist_head *head;
222 
223 	head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
224 
225 	rcu_read_lock();
226 	hlist_for_each_entry_rcu(hp, head, hash) {
227 		if (strcmp(hp->name, name)==0) {
228 			if (!kref_get_unless_zero(&hp->ref))
229 				hp = NULL;
230 			rcu_read_unlock();
231 			return hp;
232 		}
233 	}
234 	rcu_read_unlock();
235 	return NULL;
236 }
237 EXPORT_SYMBOL_GPL(auth_domain_find);
238 
239 /**
240  * auth_domain_cleanup - check that the auth_domain table is empty
241  *
242  * On module unload the auth_domain_table must be empty.  To make it
243  * easier to catch bugs which don't clean up domains properly, we
244  * warn if anything remains in the table at cleanup time.
245  *
246  * Note that we cannot proactively remove the domains at this stage.
247  * The ->release() function might be in a module that has already been
248  * unloaded.
249  */
250 
auth_domain_cleanup(void)251 void auth_domain_cleanup(void)
252 {
253 	int h;
254 	struct auth_domain *hp;
255 
256 	for (h = 0; h < DN_HASHMAX; h++)
257 		hlist_for_each_entry(hp, &auth_domain_table[h], hash)
258 			pr_warn("svc: domain %s still present at module unload.\n",
259 				hp->name);
260 }
261