Root/security/keys/request_key_auth.c

Source at commit be977234bfb4a6dca8a39e7c52165e4cd536ad71 created 9 years 5 months ago.
By Lars-Peter Clausen, jz4740: Fix compile error
1/* Request key authorisation token key definition.
2 *
3 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * See Documentation/keys-request-key.txt
12 */
13
14#include <linux/module.h>
15#include <linux/sched.h>
16#include <linux/err.h>
17#include <linux/seq_file.h>
18#include <linux/slab.h>
19#include <asm/uaccess.h>
20#include "internal.h"
21
22static int request_key_auth_instantiate(struct key *, const void *, size_t);
23static void request_key_auth_describe(const struct key *, struct seq_file *);
24static void request_key_auth_revoke(struct key *);
25static void request_key_auth_destroy(struct key *);
26static long request_key_auth_read(const struct key *, char __user *, size_t);
27
28/*
29 * The request-key authorisation key type definition.
30 */
31struct key_type key_type_request_key_auth = {
32    .name = ".request_key_auth",
33    .def_datalen = sizeof(struct request_key_auth),
34    .instantiate = request_key_auth_instantiate,
35    .describe = request_key_auth_describe,
36    .revoke = request_key_auth_revoke,
37    .destroy = request_key_auth_destroy,
38    .read = request_key_auth_read,
39};
40
41/*
42 * Instantiate a request-key authorisation key.
43 */
44static int request_key_auth_instantiate(struct key *key,
45                    const void *data,
46                    size_t datalen)
47{
48    key->payload.data = (struct request_key_auth *) data;
49    return 0;
50}
51
52/*
53 * Describe an authorisation token.
54 */
55static void request_key_auth_describe(const struct key *key,
56                      struct seq_file *m)
57{
58    struct request_key_auth *rka = key->payload.data;
59
60    seq_puts(m, "key:");
61    seq_puts(m, key->description);
62    seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
63}
64
65/*
66 * Read the callout_info data (retrieves the callout information).
67 * - the key's semaphore is read-locked
68 */
69static long request_key_auth_read(const struct key *key,
70                  char __user *buffer, size_t buflen)
71{
72    struct request_key_auth *rka = key->payload.data;
73    size_t datalen;
74    long ret;
75
76    datalen = rka->callout_len;
77    ret = datalen;
78
79    /* we can return the data as is */
80    if (buffer && buflen > 0) {
81        if (buflen > datalen)
82            buflen = datalen;
83
84        if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
85            ret = -EFAULT;
86    }
87
88    return ret;
89}
90
91/*
92 * Handle revocation of an authorisation token key.
93 *
94 * Called with the key sem write-locked.
95 */
96static void request_key_auth_revoke(struct key *key)
97{
98    struct request_key_auth *rka = key->payload.data;
99
100    kenter("{%d}", key->serial);
101
102    if (rka->cred) {
103        put_cred(rka->cred);
104        rka->cred = NULL;
105    }
106}
107
108/*
109 * Destroy an instantiation authorisation token key.
110 */
111static void request_key_auth_destroy(struct key *key)
112{
113    struct request_key_auth *rka = key->payload.data;
114
115    kenter("{%d}", key->serial);
116
117    if (rka->cred) {
118        put_cred(rka->cred);
119        rka->cred = NULL;
120    }
121
122    key_put(rka->target_key);
123    key_put(rka->dest_keyring);
124    kfree(rka->callout_info);
125    kfree(rka);
126}
127
128/*
129 * Create an authorisation token for /sbin/request-key or whoever to gain
130 * access to the caller's security data.
131 */
132struct key *request_key_auth_new(struct key *target, const void *callout_info,
133                 size_t callout_len, struct key *dest_keyring)
134{
135    struct request_key_auth *rka, *irka;
136    const struct cred *cred = current->cred;
137    struct key *authkey = NULL;
138    char desc[20];
139    int ret;
140
141    kenter("%d,", target->serial);
142
143    /* allocate a auth record */
144    rka = kmalloc(sizeof(*rka), GFP_KERNEL);
145    if (!rka) {
146        kleave(" = -ENOMEM");
147        return ERR_PTR(-ENOMEM);
148    }
149    rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
150    if (!rka->callout_info) {
151        kleave(" = -ENOMEM");
152        kfree(rka);
153        return ERR_PTR(-ENOMEM);
154    }
155
156    /* see if the calling process is already servicing the key request of
157     * another process */
158    if (cred->request_key_auth) {
159        /* it is - use that instantiation context here too */
160        down_read(&cred->request_key_auth->sem);
161
162        /* if the auth key has been revoked, then the key we're
163         * servicing is already instantiated */
164        if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
165            goto auth_key_revoked;
166
167        irka = cred->request_key_auth->payload.data;
168        rka->cred = get_cred(irka->cred);
169        rka->pid = irka->pid;
170
171        up_read(&cred->request_key_auth->sem);
172    }
173    else {
174        /* it isn't - use this process as the context */
175        rka->cred = get_cred(cred);
176        rka->pid = current->pid;
177    }
178
179    rka->target_key = key_get(target);
180    rka->dest_keyring = key_get(dest_keyring);
181    memcpy(rka->callout_info, callout_info, callout_len);
182    rka->callout_len = callout_len;
183
184    /* allocate the auth key */
185    sprintf(desc, "%x", target->serial);
186
187    authkey = key_alloc(&key_type_request_key_auth, desc,
188                cred->fsuid, cred->fsgid, cred,
189                KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
190                KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
191    if (IS_ERR(authkey)) {
192        ret = PTR_ERR(authkey);
193        goto error_alloc;
194    }
195
196    /* construct the auth key */
197    ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
198    if (ret < 0)
199        goto error_inst;
200
201    kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
202    return authkey;
203
204auth_key_revoked:
205    up_read(&cred->request_key_auth->sem);
206    kfree(rka->callout_info);
207    kfree(rka);
208    kleave("= -EKEYREVOKED");
209    return ERR_PTR(-EKEYREVOKED);
210
211error_inst:
212    key_revoke(authkey);
213    key_put(authkey);
214error_alloc:
215    key_put(rka->target_key);
216    key_put(rka->dest_keyring);
217    kfree(rka->callout_info);
218    kfree(rka);
219    kleave("= %d", ret);
220    return ERR_PTR(ret);
221}
222
223/*
224 * See if an authorisation key is associated with a particular key.
225 */
226static int key_get_instantiation_authkey_match(const struct key *key,
227                           const void *_id)
228{
229    struct request_key_auth *rka = key->payload.data;
230    key_serial_t id = (key_serial_t)(unsigned long) _id;
231
232    return rka->target_key->serial == id;
233}
234
235/*
236 * Search the current process's keyrings for the authorisation key for
237 * instantiation of a key.
238 */
239struct key *key_get_instantiation_authkey(key_serial_t target_id)
240{
241    const struct cred *cred = current_cred();
242    struct key *authkey;
243    key_ref_t authkey_ref;
244
245    authkey_ref = search_process_keyrings(
246        &key_type_request_key_auth,
247        (void *) (unsigned long) target_id,
248        key_get_instantiation_authkey_match,
249        cred);
250
251    if (IS_ERR(authkey_ref)) {
252        authkey = ERR_CAST(authkey_ref);
253        goto error;
254    }
255
256    authkey = key_ref_to_ptr(authkey_ref);
257    if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
258        key_put(authkey);
259        authkey = ERR_PTR(-EKEYREVOKED);
260    }
261
262error:
263    return authkey;
264}
265

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