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 *
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
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,
44 struct auth_cred *acred, int flags)
45 {
46 struct rpc_cred *ret;
47
48 ret = kmalloc(sizeof(*ret), rpc_task_gfp_mask());
49 if (!ret) {
50 if (!(flags & RPCAUTH_LOOKUP_ASYNC))
51 return ERR_PTR(-ENOMEM);
52 ret = mempool_alloc(unix_pool, GFP_NOWAIT);
53 if (!ret)
54 return ERR_PTR(-ENOMEM);
55 }
56 rpcauth_init_cred(ret, acred, auth, &unix_credops);
57 ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
58 return ret;
59 }
60
61 static void
62 unx_free_cred_callback(struct rcu_head *head)
63 {
64 struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
65
66 put_cred(rpc_cred->cr_cred);
67 mempool_free(rpc_cred, unix_pool);
68 }
69
70 static void
71 unx_destroy_cred(struct rpc_cred *cred)
72 {
73 call_rcu(&cred->cr_rcu, unx_free_cred_callback);
74 }
75
76 /*
77 * Match credentials against current the auth_cred.
78 */
79 static int
80 unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
81 {
82 unsigned int groups = 0;
83 unsigned int i;
84
85 if (cred->cr_cred == acred->cred)
86 return 1;
87
88 if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
89 return 0;
90
91 if (acred->cred->group_info != NULL)
92 groups = acred->cred->group_info->ngroups;
93 if (groups > UNX_NGROUPS)
94 groups = UNX_NGROUPS;
95 if (cred->cr_cred->group_info == NULL)
96 return groups == 0;
97 if (groups != cred->cr_cred->group_info->ngroups)
98 return 0;
99
100 for (i = 0; i < groups ; i++)
101 if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
102 return 0;
103 return 1;
104 }
105
106 /*
107 * Marshal credentials.
108 * Maybe we should keep a cached credential for performance reasons.
109 */
110 static int
111 unx_marshal(struct rpc_task *task, struct xdr_stream *xdr)
112 {
113 struct rpc_clnt *clnt = task->tk_client;
114 struct rpc_cred *cred = task->tk_rqstp->rq_cred;
115 __be32 *p, *cred_len, *gidarr_len;
116 int i;
117 struct group_info *gi = cred->cr_cred->group_info;
118 struct user_namespace *userns = clnt->cl_cred ?
119 clnt->cl_cred->user_ns : &init_user_ns;
120
121 /* Credential */
122
123 p = xdr_reserve_space(xdr, 3 * sizeof(*p));
124 if (!p)
125 goto marshal_failed;
126 *p++ = rpc_auth_unix;
127 cred_len = p++;
128 *p++ = xdr_zero; /* stamp */
129 if (xdr_stream_encode_opaque(xdr, clnt->cl_nodename,
130 clnt->cl_nodelen) < 0)
131 goto marshal_failed;
132 p = xdr_reserve_space(xdr, 3 * sizeof(*p));
133 if (!p)
134 goto marshal_failed;
135 *p++ = cpu_to_be32(from_kuid_munged(userns, cred->cr_cred->fsuid));
136 *p++ = cpu_to_be32(from_kgid_munged(userns, cred->cr_cred->fsgid));
137
138 gidarr_len = p++;
139 if (gi)
140 for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
141 *p++ = cpu_to_be32(from_kgid_munged(userns, gi->gid[i]));
142 *gidarr_len = cpu_to_be32(p - gidarr_len - 1);
143 *cred_len = cpu_to_be32((p - cred_len - 1) << 2);
144 p = xdr_reserve_space(xdr, (p - gidarr_len - 1) << 2);
145 if (!p)
146 goto marshal_failed;
147
148 /* Verifier */
149
150 p = xdr_reserve_space(xdr, 2 * sizeof(*p));
151 if (!p)
152 goto marshal_failed;
153 *p++ = rpc_auth_null;
154 *p = xdr_zero;
155
156 return 0;
157
158 marshal_failed:
159 return -EMSGSIZE;
160 }
161
162 /*
163 * Refresh credentials. This is a no-op for AUTH_UNIX
164 */
165 static int
166 unx_refresh(struct rpc_task *task)
167 {
168 set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
169 return 0;
170 }
171
172 static int
173 unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
174 {
175 struct rpc_auth *auth = task->tk_rqstp->rq_cred->cr_auth;
176 __be32 *p;
177 u32 size;
178
179 p = xdr_inline_decode(xdr, 2 * sizeof(*p));
180 if (!p)
181 return -EIO;
182 switch (*p++) {
183 case rpc_auth_null:
184 case rpc_auth_unix:
185 case rpc_auth_short:
186 break;
187 default:
188 return -EIO;
189 }
190 size = be32_to_cpup(p);
191 if (size > RPC_MAX_AUTH_SIZE)
192 return -EIO;
193 p = xdr_inline_decode(xdr, size);
194 if (!p)
195 return -EIO;
196
197 auth->au_verfsize = XDR_QUADLEN(size) + 2;
198 auth->au_rslack = XDR_QUADLEN(size) + 2;
199 auth->au_ralign = XDR_QUADLEN(size) + 2;
200 return 0;
201 }
202
203 int __init rpc_init_authunix(void)
204 {
205 unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
206 return unix_pool ? 0 : -ENOMEM;
207 }
208
209 void rpc_destroy_authunix(void)
210 {
211 mempool_destroy(unix_pool);
212 }
213
214 const struct rpc_authops authunix_ops = {
215 .owner = THIS_MODULE,
216 .au_flavor = RPC_AUTH_UNIX,
217 .au_name = "UNIX",
218 .create = unx_create,
219 .destroy = unx_destroy,
220 .lookup_cred = unx_lookup_cred,
221 };
222
223 static
224 struct rpc_auth unix_auth = {
225 .au_cslack = UNX_CALLSLACK,
226 .au_rslack = NUL_REPLYSLACK,
227 .au_verfsize = NUL_REPLYSLACK,
228 .au_ops = &authunix_ops,
229 .au_flavor = RPC_AUTH_UNIX,
230 .au_count = REFCOUNT_INIT(1),
231 };
232
233 static
234 const struct rpc_credops unix_credops = {
235 .cr_name = "AUTH_UNIX",
236 .crdestroy = unx_destroy_cred,
237 .crmatch = unx_match,
238 .crmarshal = unx_marshal,
239 .crwrap_req = rpcauth_wrap_req_encode,
240 .crrefresh = unx_refresh,
241 .crvalidate = unx_validate,
242 .crunwrap_resp = rpcauth_unwrap_resp_decode,
243 };
244
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