gss_krb5: Added and improved code comments
[linux-3.10.git] / net / sunrpc / auth_gss / gss_mech_switch.c
1 /*
2  *  linux/net/sunrpc/gss_mech_switch.c
3  *
4  *  Copyright (c) 2001 The Regents of the University of Michigan.
5  *  All rights reserved.
6  *
7  *  J. Bruce Fields   <bfields@umich.edu>
8  *
9  *  Redistribution and use in source and binary forms, with or without
10  *  modification, are permitted provided that the following conditions
11  *  are met:
12  *
13  *  1. Redistributions of source code must retain the above copyright
14  *     notice, this list of conditions and the following disclaimer.
15  *  2. Redistributions in binary form must reproduce the above copyright
16  *     notice, this list of conditions and the following disclaimer in the
17  *     documentation and/or other materials provided with the distribution.
18  *  3. Neither the name of the University nor the names of its
19  *     contributors may be used to endorse or promote products derived
20  *     from this software without specific prior written permission.
21  *
22  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
23  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
25  *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
29  *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
30  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
31  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
32  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33  *
34  */
35
36 #include <linux/types.h>
37 #include <linux/slab.h>
38 #include <linux/module.h>
39 #include <linux/sunrpc/msg_prot.h>
40 #include <linux/sunrpc/gss_asn1.h>
41 #include <linux/sunrpc/auth_gss.h>
42 #include <linux/sunrpc/svcauth_gss.h>
43 #include <linux/sunrpc/gss_err.h>
44 #include <linux/sunrpc/sched.h>
45 #include <linux/sunrpc/gss_api.h>
46 #include <linux/sunrpc/clnt.h>
47
48 #ifdef RPC_DEBUG
49 # define RPCDBG_FACILITY        RPCDBG_AUTH
50 #endif
51
52 static LIST_HEAD(registered_mechs);
53 static DEFINE_SPINLOCK(registered_mechs_lock);
54
55 static void
56 gss_mech_free(struct gss_api_mech *gm)
57 {
58         struct pf_desc *pf;
59         int i;
60
61         for (i = 0; i < gm->gm_pf_num; i++) {
62                 pf = &gm->gm_pfs[i];
63                 kfree(pf->auth_domain_name);
64                 pf->auth_domain_name = NULL;
65         }
66 }
67
68 static inline char *
69 make_auth_domain_name(char *name)
70 {
71         static char     *prefix = "gss/";
72         char            *new;
73
74         new = kmalloc(strlen(name) + strlen(prefix) + 1, GFP_KERNEL);
75         if (new) {
76                 strcpy(new, prefix);
77                 strcat(new, name);
78         }
79         return new;
80 }
81
82 static int
83 gss_mech_svc_setup(struct gss_api_mech *gm)
84 {
85         struct pf_desc *pf;
86         int i, status;
87
88         for (i = 0; i < gm->gm_pf_num; i++) {
89                 pf = &gm->gm_pfs[i];
90                 pf->auth_domain_name = make_auth_domain_name(pf->name);
91                 status = -ENOMEM;
92                 if (pf->auth_domain_name == NULL)
93                         goto out;
94                 status = svcauth_gss_register_pseudoflavor(pf->pseudoflavor,
95                                                         pf->auth_domain_name);
96                 if (status)
97                         goto out;
98         }
99         return 0;
100 out:
101         gss_mech_free(gm);
102         return status;
103 }
104
105 int
106 gss_mech_register(struct gss_api_mech *gm)
107 {
108         int status;
109
110         status = gss_mech_svc_setup(gm);
111         if (status)
112                 return status;
113         spin_lock(&registered_mechs_lock);
114         list_add(&gm->gm_list, &registered_mechs);
115         spin_unlock(&registered_mechs_lock);
116         dprintk("RPC:       registered gss mechanism %s\n", gm->gm_name);
117         return 0;
118 }
119
120 EXPORT_SYMBOL_GPL(gss_mech_register);
121
122 void
123 gss_mech_unregister(struct gss_api_mech *gm)
124 {
125         spin_lock(&registered_mechs_lock);
126         list_del(&gm->gm_list);
127         spin_unlock(&registered_mechs_lock);
128         dprintk("RPC:       unregistered gss mechanism %s\n", gm->gm_name);
129         gss_mech_free(gm);
130 }
131
132 EXPORT_SYMBOL_GPL(gss_mech_unregister);
133
134 struct gss_api_mech *
135 gss_mech_get(struct gss_api_mech *gm)
136 {
137         __module_get(gm->gm_owner);
138         return gm;
139 }
140
141 EXPORT_SYMBOL_GPL(gss_mech_get);
142
143 struct gss_api_mech *
144 gss_mech_get_by_name(const char *name)
145 {
146         struct gss_api_mech     *pos, *gm = NULL;
147
148         spin_lock(&registered_mechs_lock);
149         list_for_each_entry(pos, &registered_mechs, gm_list) {
150                 if (0 == strcmp(name, pos->gm_name)) {
151                         if (try_module_get(pos->gm_owner))
152                                 gm = pos;
153                         break;
154                 }
155         }
156         spin_unlock(&registered_mechs_lock);
157         return gm;
158
159 }
160
161 EXPORT_SYMBOL_GPL(gss_mech_get_by_name);
162
163 static inline int
164 mech_supports_pseudoflavor(struct gss_api_mech *gm, u32 pseudoflavor)
165 {
166         int i;
167
168         for (i = 0; i < gm->gm_pf_num; i++) {
169                 if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
170                         return 1;
171         }
172         return 0;
173 }
174
175 struct gss_api_mech *
176 gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
177 {
178         struct gss_api_mech *pos, *gm = NULL;
179
180         spin_lock(&registered_mechs_lock);
181         list_for_each_entry(pos, &registered_mechs, gm_list) {
182                 if (!mech_supports_pseudoflavor(pos, pseudoflavor)) {
183                         module_put(pos->gm_owner);
184                         continue;
185                 }
186                 if (try_module_get(pos->gm_owner))
187                         gm = pos;
188                 break;
189         }
190         spin_unlock(&registered_mechs_lock);
191         return gm;
192 }
193
194 EXPORT_SYMBOL_GPL(gss_mech_get_by_pseudoflavor);
195
196 u32
197 gss_svc_to_pseudoflavor(struct gss_api_mech *gm, u32 service)
198 {
199         int i;
200
201         for (i = 0; i < gm->gm_pf_num; i++) {
202                 if (gm->gm_pfs[i].service == service) {
203                         return gm->gm_pfs[i].pseudoflavor;
204                 }
205         }
206         return RPC_AUTH_MAXFLAVOR; /* illegal value */
207 }
208 EXPORT_SYMBOL_GPL(gss_svc_to_pseudoflavor);
209
210 u32
211 gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor)
212 {
213         int i;
214
215         for (i = 0; i < gm->gm_pf_num; i++) {
216                 if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
217                         return gm->gm_pfs[i].service;
218         }
219         return 0;
220 }
221
222 EXPORT_SYMBOL_GPL(gss_pseudoflavor_to_service);
223
224 char *
225 gss_service_to_auth_domain_name(struct gss_api_mech *gm, u32 service)
226 {
227         int i;
228
229         for (i = 0; i < gm->gm_pf_num; i++) {
230                 if (gm->gm_pfs[i].service == service)
231                         return gm->gm_pfs[i].auth_domain_name;
232         }
233         return NULL;
234 }
235
236 EXPORT_SYMBOL_GPL(gss_service_to_auth_domain_name);
237
238 void
239 gss_mech_put(struct gss_api_mech * gm)
240 {
241         if (gm)
242                 module_put(gm->gm_owner);
243 }
244
245 EXPORT_SYMBOL_GPL(gss_mech_put);
246
247 /* The mech could probably be determined from the token instead, but it's just
248  * as easy for now to pass it in. */
249 int
250 gss_import_sec_context(const void *input_token, size_t bufsize,
251                        struct gss_api_mech      *mech,
252                        struct gss_ctx           **ctx_id)
253 {
254         if (!(*ctx_id = kzalloc(sizeof(**ctx_id), GFP_KERNEL)))
255                 return -ENOMEM;
256         (*ctx_id)->mech_type = gss_mech_get(mech);
257
258         return mech->gm_ops
259                 ->gss_import_sec_context(input_token, bufsize, *ctx_id);
260 }
261
262 /* gss_get_mic: compute a mic over message and return mic_token. */
263
264 u32
265 gss_get_mic(struct gss_ctx      *context_handle,
266             struct xdr_buf      *message,
267             struct xdr_netobj   *mic_token)
268 {
269          return context_handle->mech_type->gm_ops
270                 ->gss_get_mic(context_handle,
271                               message,
272                               mic_token);
273 }
274
275 /* gss_verify_mic: check whether the provided mic_token verifies message. */
276
277 u32
278 gss_verify_mic(struct gss_ctx           *context_handle,
279                struct xdr_buf           *message,
280                struct xdr_netobj        *mic_token)
281 {
282         return context_handle->mech_type->gm_ops
283                 ->gss_verify_mic(context_handle,
284                                  message,
285                                  mic_token);
286 }
287
288 /*
289  * This function is called from both the client and server code.
290  * Each makes guarantees about how much "slack" space is available
291  * for the underlying function in "buf"'s head and tail while
292  * performing the wrap.
293  *
294  * The client and server code allocate RPC_MAX_AUTH_SIZE extra
295  * space in both the head and tail which is available for use by
296  * the wrap function.
297  *
298  * Underlying functions should verify they do not use more than
299  * RPC_MAX_AUTH_SIZE of extra space in either the head or tail
300  * when performing the wrap.
301  */
302 u32
303 gss_wrap(struct gss_ctx *ctx_id,
304          int            offset,
305          struct xdr_buf *buf,
306          struct page    **inpages)
307 {
308         return ctx_id->mech_type->gm_ops
309                 ->gss_wrap(ctx_id, offset, buf, inpages);
310 }
311
312 u32
313 gss_unwrap(struct gss_ctx       *ctx_id,
314            int                  offset,
315            struct xdr_buf       *buf)
316 {
317         return ctx_id->mech_type->gm_ops
318                 ->gss_unwrap(ctx_id, offset, buf);
319 }
320
321
322 /* gss_delete_sec_context: free all resources associated with context_handle.
323  * Note this differs from the RFC 2744-specified prototype in that we don't
324  * bother returning an output token, since it would never be used anyway. */
325
326 u32
327 gss_delete_sec_context(struct gss_ctx   **context_handle)
328 {
329         dprintk("RPC:       gss_delete_sec_context deleting %p\n",
330                         *context_handle);
331
332         if (!*context_handle)
333                 return(GSS_S_NO_CONTEXT);
334         if ((*context_handle)->internal_ctx_id)
335                 (*context_handle)->mech_type->gm_ops
336                         ->gss_delete_sec_context((*context_handle)
337                                                         ->internal_ctx_id);
338         gss_mech_put((*context_handle)->mech_type);
339         kfree(*context_handle);
340         *context_handle=NULL;
341         return GSS_S_COMPLETE;
342 }