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 int
svc_authenticate(struct svc_rqst * rqstp)64 svc_authenticate(struct svc_rqst *rqstp)
65 {
66 	rpc_authflavor_t	flavor;
67 	struct auth_ops		*aops;
68 
69 	rqstp->rq_auth_stat = rpc_auth_ok;
70 
71 	flavor = svc_getnl(&rqstp->rq_arg.head[0]);
72 
73 	dprintk("svc: svc_authenticate (%d)\n", flavor);
74 
75 	aops = svc_get_auth_ops(flavor);
76 	if (aops == NULL) {
77 		rqstp->rq_auth_stat = rpc_autherr_badcred;
78 		return SVC_DENIED;
79 	}
80 
81 	rqstp->rq_auth_slack = 0;
82 	init_svc_cred(&rqstp->rq_cred);
83 
84 	rqstp->rq_authop = aops;
85 	return aops->accept(rqstp);
86 }
87 EXPORT_SYMBOL_GPL(svc_authenticate);
88 
svc_set_client(struct svc_rqst * rqstp)89 int svc_set_client(struct svc_rqst *rqstp)
90 {
91 	rqstp->rq_client = NULL;
92 	return rqstp->rq_authop->set_client(rqstp);
93 }
94 EXPORT_SYMBOL_GPL(svc_set_client);
95 
96 /* A request, which was authenticated, has now executed.
97  * Time to finalise the credentials and verifier
98  * and release and resources
99  */
svc_authorise(struct svc_rqst * rqstp)100 int svc_authorise(struct svc_rqst *rqstp)
101 {
102 	struct auth_ops *aops = rqstp->rq_authop;
103 	int rv = 0;
104 
105 	rqstp->rq_authop = NULL;
106 
107 	if (aops) {
108 		rv = aops->release(rqstp);
109 		svc_put_auth_ops(aops);
110 	}
111 	return rv;
112 }
113 
114 int
svc_auth_register(rpc_authflavor_t flavor,struct auth_ops * aops)115 svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
116 {
117 	struct auth_ops *old;
118 	int rv = -EINVAL;
119 
120 	if (flavor < RPC_AUTH_MAXFLAVOR) {
121 		old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops);
122 		if (old == NULL || old == aops)
123 			rv = 0;
124 	}
125 	return rv;
126 }
127 EXPORT_SYMBOL_GPL(svc_auth_register);
128 
129 void
svc_auth_unregister(rpc_authflavor_t flavor)130 svc_auth_unregister(rpc_authflavor_t flavor)
131 {
132 	if (flavor < RPC_AUTH_MAXFLAVOR)
133 		rcu_assign_pointer(authtab[flavor], NULL);
134 }
135 EXPORT_SYMBOL_GPL(svc_auth_unregister);
136 
137 /**************************************************
138  * 'auth_domains' are stored in a hash table indexed by name.
139  * When the last reference to an 'auth_domain' is dropped,
140  * the object is unhashed and freed.
141  * If auth_domain_lookup fails to find an entry, it will return
142  * it's second argument 'new'.  If this is non-null, it will
143  * have been atomically linked into the table.
144  */
145 
146 #define	DN_HASHBITS	6
147 #define	DN_HASHMAX	(1<<DN_HASHBITS)
148 
149 static struct hlist_head	auth_domain_table[DN_HASHMAX];
150 static DEFINE_SPINLOCK(auth_domain_lock);
151 
auth_domain_release(struct kref * kref)152 static void auth_domain_release(struct kref *kref)
153 	__releases(&auth_domain_lock)
154 {
155 	struct auth_domain *dom = container_of(kref, struct auth_domain, ref);
156 
157 	hlist_del_rcu(&dom->hash);
158 	dom->flavour->domain_release(dom);
159 	spin_unlock(&auth_domain_lock);
160 }
161 
auth_domain_put(struct auth_domain * dom)162 void auth_domain_put(struct auth_domain *dom)
163 {
164 	kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock);
165 }
166 EXPORT_SYMBOL_GPL(auth_domain_put);
167 
168 struct auth_domain *
auth_domain_lookup(char * name,struct auth_domain * new)169 auth_domain_lookup(char *name, struct auth_domain *new)
170 {
171 	struct auth_domain *hp;
172 	struct hlist_head *head;
173 
174 	head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
175 
176 	spin_lock(&auth_domain_lock);
177 
178 	hlist_for_each_entry(hp, head, hash) {
179 		if (strcmp(hp->name, name)==0) {
180 			kref_get(&hp->ref);
181 			spin_unlock(&auth_domain_lock);
182 			return hp;
183 		}
184 	}
185 	if (new)
186 		hlist_add_head_rcu(&new->hash, head);
187 	spin_unlock(&auth_domain_lock);
188 	return new;
189 }
190 EXPORT_SYMBOL_GPL(auth_domain_lookup);
191 
auth_domain_find(char * name)192 struct auth_domain *auth_domain_find(char *name)
193 {
194 	struct auth_domain *hp;
195 	struct hlist_head *head;
196 
197 	head = &auth_domain_table[hash_str(name, DN_HASHBITS)];
198 
199 	rcu_read_lock();
200 	hlist_for_each_entry_rcu(hp, head, hash) {
201 		if (strcmp(hp->name, name)==0) {
202 			if (!kref_get_unless_zero(&hp->ref))
203 				hp = NULL;
204 			rcu_read_unlock();
205 			return hp;
206 		}
207 	}
208 	rcu_read_unlock();
209 	return NULL;
210 }
211 EXPORT_SYMBOL_GPL(auth_domain_find);
212 
213 /**
214  * auth_domain_cleanup - check that the auth_domain table is empty
215  *
216  * On module unload the auth_domain_table must be empty.  To make it
217  * easier to catch bugs which don't clean up domains properly, we
218  * warn if anything remains in the table at cleanup time.
219  *
220  * Note that we cannot proactively remove the domains at this stage.
221  * The ->release() function might be in a module that has already been
222  * unloaded.
223  */
224 
auth_domain_cleanup(void)225 void auth_domain_cleanup(void)
226 {
227 	int h;
228 	struct auth_domain *hp;
229 
230 	for (h = 0; h < DN_HASHMAX; h++)
231 		hlist_for_each_entry(hp, &auth_domain_table[h], hash)
232 			pr_warn("svc: domain %s still present at module unload.\n",
233 				hp->name);
234 }
235