1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/net/sunrpc/auth_unix.c
4  *
5  * UNIX-style authentication; no AUTH_SHORT support
6  *
7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
8  */
9 
10 #include <linux/slab.h>
11 #include <linux/types.h>
12 #include <linux/sched.h>
13 #include <linux/module.h>
14 #include <linux/mempool.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/sunrpc/auth.h>
17 #include <linux/user_namespace.h>
18 
19 
20 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
21 # define RPCDBG_FACILITY	RPCDBG_AUTH
22 #endif
23 
24 static struct rpc_auth		unix_auth;
25 static const struct rpc_credops	unix_credops;
26 static mempool_t		*unix_pool;
27 
28 static struct rpc_auth *
unx_create(const struct rpc_auth_create_args * args,struct rpc_clnt * clnt)29 unx_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
30 {
31 	refcount_inc(&unix_auth.au_count);
32 	return &unix_auth;
33 }
34 
35 static void
unx_destroy(struct rpc_auth * auth)36 unx_destroy(struct rpc_auth *auth)
37 {
38 }
39 
40 /*
41  * Lookup AUTH_UNIX creds for current process
42  */
43 static struct rpc_cred *
unx_lookup_cred(struct rpc_auth * auth,struct auth_cred * acred,int flags)44 unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
45 {
46 	struct rpc_cred *ret = mempool_alloc(unix_pool, GFP_NOFS);
47 
48 	rpcauth_init_cred(ret, acred, auth, &unix_credops);
49 	ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
50 	return ret;
51 }
52 
53 static void
unx_free_cred_callback(struct rcu_head * head)54 unx_free_cred_callback(struct rcu_head *head)
55 {
56 	struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
57 
58 	put_cred(rpc_cred->cr_cred);
59 	mempool_free(rpc_cred, unix_pool);
60 }
61 
62 static void
unx_destroy_cred(struct rpc_cred * cred)63 unx_destroy_cred(struct rpc_cred *cred)
64 {
65 	call_rcu(&cred->cr_rcu, unx_free_cred_callback);
66 }
67 
68 /*
69  * Match credentials against current the auth_cred.
70  */
71 static int
unx_match(struct auth_cred * acred,struct rpc_cred * cred,int flags)72 unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
73 {
74 	unsigned int groups = 0;
75 	unsigned int i;
76 
77 	if (cred->cr_cred == acred->cred)
78 		return 1;
79 
80 	if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
81 		return 0;
82 
83 	if (acred->cred->group_info != NULL)
84 		groups = acred->cred->group_info->ngroups;
85 	if (groups > UNX_NGROUPS)
86 		groups = UNX_NGROUPS;
87 	if (cred->cr_cred->group_info == NULL)
88 		return groups == 0;
89 	if (groups != cred->cr_cred->group_info->ngroups)
90 		return 0;
91 
92 	for (i = 0; i < groups ; i++)
93 		if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
94 			return 0;
95 	return 1;
96 }
97 
98 /*
99  * Marshal credentials.
100  * Maybe we should keep a cached credential for performance reasons.
101  */
102 static int
unx_marshal(struct rpc_task * task,struct xdr_stream * xdr)103 unx_marshal(struct rpc_task *task, struct xdr_stream *xdr)
104 {
105 	struct rpc_clnt	*clnt = task->tk_client;
106 	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
107 	__be32		*p, *cred_len, *gidarr_len;
108 	int		i;
109 	struct group_info *gi = cred->cr_cred->group_info;
110 	struct user_namespace *userns = clnt->cl_cred ?
111 		clnt->cl_cred->user_ns : &init_user_ns;
112 
113 	/* Credential */
114 
115 	p = xdr_reserve_space(xdr, 3 * sizeof(*p));
116 	if (!p)
117 		goto marshal_failed;
118 	*p++ = rpc_auth_unix;
119 	cred_len = p++;
120 	*p++ = xdr_zero;	/* stamp */
121 	if (xdr_stream_encode_opaque(xdr, clnt->cl_nodename,
122 				     clnt->cl_nodelen) < 0)
123 		goto marshal_failed;
124 	p = xdr_reserve_space(xdr, 3 * sizeof(*p));
125 	if (!p)
126 		goto marshal_failed;
127 	*p++ = cpu_to_be32(from_kuid_munged(userns, cred->cr_cred->fsuid));
128 	*p++ = cpu_to_be32(from_kgid_munged(userns, cred->cr_cred->fsgid));
129 
130 	gidarr_len = p++;
131 	if (gi)
132 		for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
133 			*p++ = cpu_to_be32(from_kgid_munged(userns, gi->gid[i]));
134 	*gidarr_len = cpu_to_be32(p - gidarr_len - 1);
135 	*cred_len = cpu_to_be32((p - cred_len - 1) << 2);
136 	p = xdr_reserve_space(xdr, (p - gidarr_len - 1) << 2);
137 	if (!p)
138 		goto marshal_failed;
139 
140 	/* Verifier */
141 
142 	p = xdr_reserve_space(xdr, 2 * sizeof(*p));
143 	if (!p)
144 		goto marshal_failed;
145 	*p++ = rpc_auth_null;
146 	*p   = xdr_zero;
147 
148 	return 0;
149 
150 marshal_failed:
151 	return -EMSGSIZE;
152 }
153 
154 /*
155  * Refresh credentials. This is a no-op for AUTH_UNIX
156  */
157 static int
unx_refresh(struct rpc_task * task)158 unx_refresh(struct rpc_task *task)
159 {
160 	set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
161 	return 0;
162 }
163 
164 static int
unx_validate(struct rpc_task * task,struct xdr_stream * xdr)165 unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
166 {
167 	struct rpc_auth *auth = task->tk_rqstp->rq_cred->cr_auth;
168 	__be32 *p;
169 	u32 size;
170 
171 	p = xdr_inline_decode(xdr, 2 * sizeof(*p));
172 	if (!p)
173 		return -EIO;
174 	switch (*p++) {
175 	case rpc_auth_null:
176 	case rpc_auth_unix:
177 	case rpc_auth_short:
178 		break;
179 	default:
180 		return -EIO;
181 	}
182 	size = be32_to_cpup(p);
183 	if (size > RPC_MAX_AUTH_SIZE)
184 		return -EIO;
185 	p = xdr_inline_decode(xdr, size);
186 	if (!p)
187 		return -EIO;
188 
189 	auth->au_verfsize = XDR_QUADLEN(size) + 2;
190 	auth->au_rslack = XDR_QUADLEN(size) + 2;
191 	auth->au_ralign = XDR_QUADLEN(size) + 2;
192 	return 0;
193 }
194 
rpc_init_authunix(void)195 int __init rpc_init_authunix(void)
196 {
197 	unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
198 	return unix_pool ? 0 : -ENOMEM;
199 }
200 
rpc_destroy_authunix(void)201 void rpc_destroy_authunix(void)
202 {
203 	mempool_destroy(unix_pool);
204 }
205 
206 const struct rpc_authops authunix_ops = {
207 	.owner		= THIS_MODULE,
208 	.au_flavor	= RPC_AUTH_UNIX,
209 	.au_name	= "UNIX",
210 	.create		= unx_create,
211 	.destroy	= unx_destroy,
212 	.lookup_cred	= unx_lookup_cred,
213 };
214 
215 static
216 struct rpc_auth		unix_auth = {
217 	.au_cslack	= UNX_CALLSLACK,
218 	.au_rslack	= NUL_REPLYSLACK,
219 	.au_verfsize	= NUL_REPLYSLACK,
220 	.au_ops		= &authunix_ops,
221 	.au_flavor	= RPC_AUTH_UNIX,
222 	.au_count	= REFCOUNT_INIT(1),
223 };
224 
225 static
226 const struct rpc_credops unix_credops = {
227 	.cr_name	= "AUTH_UNIX",
228 	.crdestroy	= unx_destroy_cred,
229 	.crmatch	= unx_match,
230 	.crmarshal	= unx_marshal,
231 	.crwrap_req	= rpcauth_wrap_req_encode,
232 	.crrefresh	= unx_refresh,
233 	.crvalidate	= unx_validate,
234 	.crunwrap_resp	= rpcauth_unwrap_resp_decode,
235 };
236