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
19struct 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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
29# define RPCDBG_FACILITY	RPCDBG_AUTH
30#endif
31
32static struct rpc_auth		unix_auth;
33static const struct rpc_credops	unix_credops;
34
35static struct rpc_auth *
36unx_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
44static void
45unx_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 */
54static struct rpc_cred *
55unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
56{
57	return rpcauth_lookup_credcache(auth, acred, flags);
58}
59
60static struct rpc_cred *
61unx_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
91static void
92unx_free_cred(struct unx_cred *unx_cred)
93{
94	dprintk("RPC:       unx_free_cred %p\n", unx_cred);
95	kfree(unx_cred);
96}
97
98static void
99unx_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
105static void
106unx_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 */
116static int
117unx_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 */
143static __be32 *
144unx_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 */
177static int
178unx_refresh(struct rpc_task *task)
179{
180	set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
181	return 0;
182}
183
184static __be32 *
185unx_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
209int __init rpc_init_authunix(void)
210{
211	return rpcauth_init_credcache(&unix_auth);
212}
213
214void rpc_destroy_authunix(void)
215{
216	rpcauth_destroy_credcache(&unix_auth);
217}
218
219const 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
229static
230struct 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
238static
239const 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