1 /*
2 * Copyright (c) 1999-2009 Apple, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/proc.h>
33 #include <sys/errno.h>
34 #include <sys/ioctl.h>
35 #include <sys/conf.h>
36 #include <sys/fcntl.h>
37 #include <string.h>
38 #include <miscfs/devfs/devfs.h>
39 #include <kern/locks.h>
40 #include <kern/clock.h>
41 #include <sys/time.h>
42 #include <sys/malloc.h>
43 #include <sys/sysproto.h>
44 #include <sys/uio_internal.h>
45
46 #include <dev/random/randomdev.h>
47
48 #include <libkern/OSByteOrder.h>
49 #include <libkern/OSAtomic.h>
50
51 #include <mach/mach_time.h>
52
53 #define RANDOM_MAJOR -1 /* let the kernel pick the device number */
54 #define RANDOM_MINOR 0
55 #define URANDOM_MINOR 1
56
57 d_ioctl_t random_ioctl;
58
59 static int
random_stop(__unused struct tty * tp,__unused int rw)60 random_stop(__unused struct tty *tp, __unused int rw)
61 {
62 return 0;
63 }
64
65 static int
random_reset(__unused int uban)66 random_reset(__unused int uban)
67 {
68 return 0;
69 }
70
71 static int
random_select(__unused dev_t dev,__unused int which,__unused void * wql,__unused struct proc * p)72 random_select(__unused dev_t dev, __unused int which, __unused void *wql,
73 __unused struct proc *p)
74 {
75 return ENODEV;
76 }
77
78 static const struct cdevsw random_cdevsw =
79 {
80 .d_open = random_open,
81 .d_close = random_close,
82 .d_read = random_read,
83 .d_write = random_write,
84 .d_ioctl = random_ioctl,
85 .d_stop = random_stop,
86 .d_reset = random_reset,
87 .d_select = random_select,
88 .d_mmap = eno_mmap,
89 .d_strategy = eno_strat,
90 .d_reserved_1 = eno_getc,
91 .d_reserved_2 = eno_putc,
92 };
93
94
95 /*
96 * Called to initialize our device,
97 * and to register ourselves with devfs
98 */
99 void
random_init(void)100 random_init(void)
101 {
102 int ret;
103
104 ret = cdevsw_add(RANDOM_MAJOR, &random_cdevsw);
105 if (ret < 0) {
106 panic("random_init: failed to allocate a major number!");
107 }
108
109 devfs_make_node(makedev(ret, RANDOM_MINOR), DEVFS_CHAR,
110 UID_ROOT, GID_WHEEL, 0666, "random");
111
112 /*
113 * also make urandom
114 * (which is exactly the same thing in our context)
115 */
116 devfs_make_node(makedev(ret, URANDOM_MINOR), DEVFS_CHAR,
117 UID_ROOT, GID_WHEEL, 0666, "urandom");
118 }
119
120 int
random_ioctl(__unused dev_t dev,u_long cmd,__unused caddr_t data,__unused int flag,__unused struct proc * p)121 random_ioctl( __unused dev_t dev, u_long cmd, __unused caddr_t data,
122 __unused int flag, __unused struct proc *p )
123 {
124 switch (cmd) {
125 case FIONBIO:
126 case FIOASYNC:
127 break;
128 default:
129 return ENODEV;
130 }
131
132 return 0;
133 }
134
135 /*
136 * Open the device. Make sure init happened, and make sure the caller is
137 * authorized.
138 */
139
140 int
random_open(__unused dev_t dev,int flags,__unused int devtype,__unused struct proc * p)141 random_open(__unused dev_t dev, int flags, __unused int devtype, __unused struct proc *p)
142 {
143 /*
144 * if we are being opened for write,
145 * make sure that we have privledges do so
146 */
147 if (flags & FWRITE) {
148 if (securelevel >= 2) {
149 return EPERM;
150 }
151 #ifndef __APPLE__
152 if ((securelevel >= 1) && proc_suser(p)) {
153 return EPERM;
154 }
155 #endif /* !__APPLE__ */
156 }
157
158 return 0;
159 }
160
161
162 /*
163 * close the device.
164 */
165
166 int
random_close(__unused dev_t dev,__unused int flags,__unused int mode,__unused struct proc * p)167 random_close(__unused dev_t dev, __unused int flags, __unused int mode, __unused struct proc *p)
168 {
169 return 0;
170 }
171
172
173 /*
174 * Get entropic data from the Security Server, and use it to reseed the
175 * prng.
176 */
177 int
random_write(dev_t dev,struct uio * uio,__unused int ioflag)178 random_write(dev_t dev, struct uio *uio, __unused int ioflag)
179 {
180 int retCode = 0;
181 char rdBuffer[256];
182
183 if (minor(dev) != RANDOM_MINOR) {
184 return EPERM;
185 }
186
187 /* Security server is sending us entropy */
188
189 while ((size_t)uio_resid(uio) > 0 && retCode == 0) {
190 /* get the user's data */
191 size_t bytesToInput = MIN((size_t)uio_resid(uio), sizeof(rdBuffer));
192 retCode = uiomove(rdBuffer, (int)bytesToInput, uio);
193 if (retCode != 0) {
194 break;
195 }
196 retCode = write_random(rdBuffer, (u_int)bytesToInput);
197 if (retCode != 0) {
198 break;
199 }
200 }
201
202 return retCode;
203 }
204
205 /*
206 * return data to the caller. Results unpredictable.
207 */
208 int
random_read(__unused dev_t dev,struct uio * uio,__unused int ioflag)209 random_read(__unused dev_t dev, struct uio *uio, __unused int ioflag)
210 {
211 int retCode = 0;
212 char buffer[512];
213
214 size_t bytes_remaining = (size_t)uio_resid(uio);
215 while (bytes_remaining > 0 && retCode == 0) {
216 size_t bytesToRead = MIN(bytes_remaining, sizeof(buffer));
217 read_random(buffer, (u_int)bytesToRead);
218
219 retCode = uiomove(buffer, (int)bytesToRead, uio);
220 if (retCode != 0) {
221 break;
222 }
223
224 bytes_remaining = (size_t)uio_resid(uio);
225 }
226
227 return retCode;
228 }
229
230 /*
231 * Return an u_int32_t pseudo-random number.
232 */
233 u_int32_t
RandomULong(void)234 RandomULong(void)
235 {
236 u_int32_t buf;
237 read_random(&buf, sizeof(buf));
238 return buf;
239 }
240
241
242 int
getentropy(__unused struct proc * p,struct getentropy_args * gap,__unused int * ret)243 getentropy(__unused struct proc * p, struct getentropy_args *gap, __unused int * ret)
244 {
245 user_addr_t user_addr;
246 user_size_t user_size;
247 char buffer[256];
248
249 user_addr = (user_addr_t)gap->buffer;
250 user_size = gap->size;
251 /* Can't request more than 256 random bytes
252 * at once. Complying with openbsd getentropy()
253 */
254 if (user_size > sizeof(buffer)) {
255 return EINVAL;
256 }
257 read_random(buffer, (u_int)user_size);
258 return copyout(buffer, user_addr, user_size);
259 }
260