xref: /openbmc/linux/net/sunrpc/auth_unix.c (revision 12eb4683)
1 /*
2  * linux/net/sunrpc/auth_unix.c
3  *
4  * UNIX-style authentication; no AUTH_SHORT support
5  *
6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/slab.h>
10 #include <linux/types.h>
11 #include <linux/sched.h>
12 #include <linux/module.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/sunrpc/auth.h>
15 #include <linux/user_namespace.h>
16 
17 #define NFS_NGROUPS	16
18 
19 struct unx_cred {
20 	struct rpc_cred		uc_base;
21 	kgid_t			uc_gid;
22 	kgid_t			uc_gids[NFS_NGROUPS];
23 };
24 #define uc_uid			uc_base.cr_uid
25 
26 #define UNX_WRITESLACK		(21 + (UNX_MAXNODENAME >> 2))
27 
28 #ifdef RPC_DEBUG
29 # define RPCDBG_FACILITY	RPCDBG_AUTH
30 #endif
31 
32 static struct rpc_auth		unix_auth;
33 static const struct rpc_credops	unix_credops;
34 
35 static struct rpc_auth *
36 unx_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
37 {
38 	dprintk("RPC:       creating UNIX authenticator for client %p\n",
39 			clnt);
40 	atomic_inc(&unix_auth.au_count);
41 	return &unix_auth;
42 }
43 
44 static void
45 unx_destroy(struct rpc_auth *auth)
46 {
47 	dprintk("RPC:       destroying UNIX authenticator %p\n", auth);
48 	rpcauth_clear_credcache(auth->au_credcache);
49 }
50 
51 /*
52  * Lookup AUTH_UNIX creds for current process
53  */
54 static struct rpc_cred *
55 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
56 {
57 	return rpcauth_lookup_credcache(auth, acred, flags);
58 }
59 
60 static struct rpc_cred *
61 unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
62 {
63 	struct unx_cred	*cred;
64 	unsigned int groups = 0;
65 	unsigned int i;
66 
67 	dprintk("RPC:       allocating UNIX cred for uid %d gid %d\n",
68 			from_kuid(&init_user_ns, acred->uid),
69 			from_kgid(&init_user_ns, acred->gid));
70 
71 	if (!(cred = kmalloc(sizeof(*cred), GFP_NOFS)))
72 		return ERR_PTR(-ENOMEM);
73 
74 	rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
75 	cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
76 
77 	if (acred->group_info != NULL)
78 		groups = acred->group_info->ngroups;
79 	if (groups > NFS_NGROUPS)
80 		groups = NFS_NGROUPS;
81 
82 	cred->uc_gid = acred->gid;
83 	for (i = 0; i < groups; i++)
84 		cred->uc_gids[i] = GROUP_AT(acred->group_info, i);
85 	if (i < NFS_NGROUPS)
86 		cred->uc_gids[i] = INVALID_GID;
87 
88 	return &cred->uc_base;
89 }
90 
91 static void
92 unx_free_cred(struct unx_cred *unx_cred)
93 {
94 	dprintk("RPC:       unx_free_cred %p\n", unx_cred);
95 	kfree(unx_cred);
96 }
97 
98 static void
99 unx_free_cred_callback(struct rcu_head *head)
100 {
101 	struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
102 	unx_free_cred(unx_cred);
103 }
104 
105 static void
106 unx_destroy_cred(struct rpc_cred *cred)
107 {
108 	call_rcu(&cred->cr_rcu, unx_free_cred_callback);
109 }
110 
111 /*
112  * Match credentials against current process creds.
113  * The root_override argument takes care of cases where the caller may
114  * request root creds (e.g. for NFS swapping).
115  */
116 static int
117 unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
118 {
119 	struct unx_cred	*cred = container_of(rcred, struct unx_cred, uc_base);
120 	unsigned int groups = 0;
121 	unsigned int i;
122 
123 
124 	if (!uid_eq(cred->uc_uid, acred->uid) || !gid_eq(cred->uc_gid, acred->gid))
125 		return 0;
126 
127 	if (acred->group_info != NULL)
128 		groups = acred->group_info->ngroups;
129 	if (groups > NFS_NGROUPS)
130 		groups = NFS_NGROUPS;
131 	for (i = 0; i < groups ; i++)
132 		if (!gid_eq(cred->uc_gids[i], GROUP_AT(acred->group_info, i)))
133 			return 0;
134 	if (groups < NFS_NGROUPS && gid_valid(cred->uc_gids[groups]))
135 		return 0;
136 	return 1;
137 }
138 
139 /*
140  * Marshal credentials.
141  * Maybe we should keep a cached credential for performance reasons.
142  */
143 static __be32 *
144 unx_marshal(struct rpc_task *task, __be32 *p)
145 {
146 	struct rpc_clnt	*clnt = task->tk_client;
147 	struct unx_cred	*cred = container_of(task->tk_rqstp->rq_cred, struct unx_cred, uc_base);
148 	__be32		*base, *hold;
149 	int		i;
150 
151 	*p++ = htonl(RPC_AUTH_UNIX);
152 	base = p++;
153 	*p++ = htonl(jiffies/HZ);
154 
155 	/*
156 	 * Copy the UTS nodename captured when the client was created.
157 	 */
158 	p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
159 
160 	*p++ = htonl((u32) from_kuid(&init_user_ns, cred->uc_uid));
161 	*p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gid));
162 	hold = p++;
163 	for (i = 0; i < 16 && gid_valid(cred->uc_gids[i]); i++)
164 		*p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gids[i]));
165 	*hold = htonl(p - hold - 1);		/* gid array length */
166 	*base = htonl((p - base - 1) << 2);	/* cred length */
167 
168 	*p++ = htonl(RPC_AUTH_NULL);
169 	*p++ = htonl(0);
170 
171 	return p;
172 }
173 
174 /*
175  * Refresh credentials. This is a no-op for AUTH_UNIX
176  */
177 static int
178 unx_refresh(struct rpc_task *task)
179 {
180 	set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
181 	return 0;
182 }
183 
184 static __be32 *
185 unx_validate(struct rpc_task *task, __be32 *p)
186 {
187 	rpc_authflavor_t	flavor;
188 	u32			size;
189 
190 	flavor = ntohl(*p++);
191 	if (flavor != RPC_AUTH_NULL &&
192 	    flavor != RPC_AUTH_UNIX &&
193 	    flavor != RPC_AUTH_SHORT) {
194 		printk("RPC: bad verf flavor: %u\n", flavor);
195 		return ERR_PTR(-EIO);
196 	}
197 
198 	size = ntohl(*p++);
199 	if (size > RPC_MAX_AUTH_SIZE) {
200 		printk("RPC: giant verf size: %u\n", size);
201 		return ERR_PTR(-EIO);
202 	}
203 	task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
204 	p += (size >> 2);
205 
206 	return p;
207 }
208 
209 int __init rpc_init_authunix(void)
210 {
211 	return rpcauth_init_credcache(&unix_auth);
212 }
213 
214 void rpc_destroy_authunix(void)
215 {
216 	rpcauth_destroy_credcache(&unix_auth);
217 }
218 
219 const struct rpc_authops authunix_ops = {
220 	.owner		= THIS_MODULE,
221 	.au_flavor	= RPC_AUTH_UNIX,
222 	.au_name	= "UNIX",
223 	.create		= unx_create,
224 	.destroy	= unx_destroy,
225 	.lookup_cred	= unx_lookup_cred,
226 	.crcreate	= unx_create_cred,
227 };
228 
229 static
230 struct rpc_auth		unix_auth = {
231 	.au_cslack	= UNX_WRITESLACK,
232 	.au_rslack	= 2,			/* assume AUTH_NULL verf */
233 	.au_ops		= &authunix_ops,
234 	.au_flavor	= RPC_AUTH_UNIX,
235 	.au_count	= ATOMIC_INIT(0),
236 };
237 
238 static
239 const struct rpc_credops unix_credops = {
240 	.cr_name	= "AUTH_UNIX",
241 	.crdestroy	= unx_destroy_cred,
242 	.crbind		= rpcauth_generic_bind_cred,
243 	.crmatch	= unx_match,
244 	.crmarshal	= unx_marshal,
245 	.crrefresh	= unx_refresh,
246 	.crvalidate	= unx_validate,
247 };
248