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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: lmem.c,v 1.5 2004/04/02 01:03:49 mdw Exp $ |
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4 | * |
5 | * Locked memory allocation (Unix-specific) |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: lmem.c,v $ |
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33 | * Revision 1.5 2004/04/02 01:03:49 mdw |
34 | * Miscellaneous constification. |
35 | * |
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36 | * Revision 1.4 2002/01/24 22:26:11 mdw |
37 | * Fix build failure when @mlock@ not available. |
38 | * |
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39 | * Revision 1.3 2000/07/29 21:58:15 mdw |
40 | * (l_destroy): New function for destroying locked memory blocks. |
41 | * |
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42 | * Revision 1.2 2000/06/17 11:29:20 mdw |
43 | * Add arena support. |
44 | * |
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45 | * Revision 1.1 1999/12/22 16:02:52 mdw |
46 | * Interface to allocating `locked' memory (which isn't paged out). |
47 | * |
48 | */ |
49 | |
50 | /*----- Header files ------------------------------------------------------*/ |
51 | |
52 | #include "config.h" |
53 | |
54 | #include <assert.h> |
55 | #include <errno.h> |
56 | #include <stdio.h> |
57 | #include <stdlib.h> |
58 | #include <string.h> |
59 | |
60 | #include <sys/types.h> |
61 | #include <unistd.h> |
62 | |
63 | #ifdef HAVE_MLOCK |
64 | # include <sys/mman.h> |
65 | #endif |
66 | |
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67 | #include <mLib/arena.h> |
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68 | #include <mLib/dstr.h> |
69 | #include <mLib/sub.h> |
70 | |
71 | #include "lmem.h" |
72 | |
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73 | /*----- Arena operations --------------------------------------------------*/ |
74 | |
75 | static void *aalloc(arena *a, size_t sz) { return l_alloc((lmem *)a, sz); } |
76 | static void afree(arena *a, void *p) { l_free((lmem *)a, p); } |
77 | static void apurge(arena *a) { l_purge((lmem *)a); } |
78 | |
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79 | static const arena_ops l_ops = { aalloc, arena_fakerealloc, afree, apurge }; |
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80 | |
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81 | /*----- Main code ---------------------------------------------------------*/ |
82 | |
83 | /* --- @l_init@ --- * |
84 | * |
85 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
86 | * @size_t sz@ = size of locked memory area requested |
87 | * |
88 | * Returns: Zero if everything is fine, @+1@ if some insecure memory was |
89 | * allocated, and @-1@ if everything went horribly wrong. |
90 | * |
91 | * Use: Initializes the locked memory manager. This function is safe |
92 | * to call in a privileged program; privileges should usually be |
93 | * dropped after allocating the locked memory block. |
94 | * |
95 | * You must call @sub_init@ before allocating locked memory |
96 | * buffers. |
97 | */ |
98 | |
99 | int l_init(lmem *lm, size_t sz) |
100 | { |
101 | char *p; |
102 | int rc = 0; |
103 | l_node *l; |
104 | |
105 | /* --- Preliminaries --- */ |
106 | |
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107 | lm->a.ops = &l_ops; |
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108 | lm->err = 0; |
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109 | lm->f = 0; |
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110 | |
111 | /* --- Try making a secure locked passphrase buffer --- * |
112 | * |
113 | * Drop privileges before emitting diagnostic messages. |
114 | */ |
115 | |
116 | #ifdef HAVE_MLOCK |
117 | |
118 | /* --- Memory-map a page from somewhere --- */ |
119 | |
120 | # ifdef MAP_ANON |
121 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); |
122 | # else |
123 | { |
124 | int fd; |
125 | if ((fd = open("/dev/zero", O_RDWR)) >= 0) { |
126 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); |
127 | close(fd); |
128 | } |
129 | } |
130 | # endif |
131 | |
132 | /* --- Lock the page in memory --- * |
133 | * |
134 | * Why does @mmap@ return such a stupid result if it fails? |
135 | */ |
136 | |
137 | if (p == 0 || p == MAP_FAILED) { |
138 | lm->emsg = "couldn't map locked memory area: %s"; |
139 | lm->err = errno; |
140 | p = 0; |
141 | } else if (mlock(p, sz)) { |
142 | lm->emsg = "error locking memory area: %s"; |
143 | lm->err = errno; |
144 | munmap(p, sz); |
145 | p = 0; |
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146 | } else |
147 | lm->f |= LF_LOCKED; |
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148 | |
149 | #endif |
150 | |
151 | /* --- Make a standard passphrase buffer --- */ |
152 | |
153 | #ifdef HAVE_MLOCK |
154 | if (!p) |
155 | #else |
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156 | lm->err = 0; |
157 | lm->emsg = "locked memory not available on this system"; |
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158 | #endif |
159 | { |
160 | if ((p = malloc(sz)) == 0) { |
161 | lm->emsg = "not enough standard memory!"; |
162 | lm->err = ENOMEM; |
163 | return (-1); |
164 | } |
165 | rc = +1; |
166 | } |
167 | |
168 | /* --- Initialize the buffer --- */ |
169 | |
170 | lm->sz = lm->free = sz; |
171 | lm->p = p; |
172 | |
173 | /* --- Initialize the free list --- */ |
174 | |
175 | l = CREATE(l_node); |
176 | l->next = 0; |
177 | l->p = p; |
178 | l->sz = sz; |
179 | l->f = 0; |
180 | lm->l = l; |
181 | |
182 | /* --- Done --- */ |
183 | |
184 | return (rc); |
185 | } |
186 | |
187 | /* --- @l_alloc@ --- * |
188 | * |
189 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
190 | * @size_t sz@ = size requested |
191 | * |
192 | * Returns: Pointer to allocated memory. |
193 | * |
194 | * Use: Allocates @sz@ bytes of locked memory. |
195 | */ |
196 | |
197 | void *l_alloc(lmem *lm, size_t sz) |
198 | { |
199 | l_node *l; |
200 | |
201 | sz = (sz + 3u) & ~3u; |
202 | for (l = lm->l; l; l = l->next) { |
203 | if (l->f & LF_ALLOC) |
204 | continue; |
205 | if (l->sz < sz) |
206 | continue; |
207 | l->f |= LF_ALLOC; |
208 | if (l->sz > sz) { |
209 | l_node *n = CREATE(l_node); |
210 | n->next = l->next; |
211 | n->p = l->p + sz; |
212 | n->sz = l->sz - sz; |
213 | l->sz = sz; |
214 | n->f = 0; |
215 | l->next = n; |
216 | } |
217 | assert(((void)"Locked buffer space has vanished", lm->free >= sz)); |
218 | lm->free -= sz; |
219 | return (l->p); |
220 | } |
221 | return (0); |
222 | } |
223 | |
224 | /* --- @l_free@ --- * |
225 | * |
226 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
227 | * @void *p@ = pointer to block |
228 | * |
229 | * Returns: --- |
230 | * |
231 | * Use: Releases a block of locked memory. |
232 | */ |
233 | |
234 | void l_free(lmem *lm, void *p) |
235 | { |
236 | l_node *l; |
237 | l_node *ll = 0; |
238 | |
239 | for (l = lm->l; l; l = l->next) { |
240 | size_t sz; |
241 | |
242 | /* --- If this isn't the block, skip it --- */ |
243 | |
244 | if (l->p != p) { |
245 | ll = l; |
246 | continue; |
247 | } |
248 | assert(((void)"Block is already free", l->f & LF_ALLOC)); |
249 | |
250 | /* --- Coalesce with adjacent free blocks --- */ |
251 | |
252 | l->f &= ~LF_ALLOC; |
253 | sz = l->sz; |
254 | memset(p, 0, sz); |
255 | |
256 | if (ll && !(ll->f & LF_ALLOC)) { |
257 | assert(((void)"Previous block doesn't fit", ll->p + ll->sz == p)); |
258 | ll->sz += sz; |
259 | ll->next = l->next; |
260 | DESTROY(l); |
261 | l = ll; |
262 | } |
263 | |
264 | ll = l->next; |
265 | if (ll && !(ll->f & LF_ALLOC)) { |
266 | assert(((void)"Next block doesn't fit", ll->p == l->p + l->sz)); |
267 | l->sz += ll->sz; |
268 | l->next = ll->next; |
269 | DESTROY(ll); |
270 | } |
271 | |
272 | lm->free += sz; |
273 | assert(((void)"Free lunch", lm->free <= lm->sz)); |
274 | return; |
275 | } |
276 | assert(((void)"Not a locked block", 0)); |
277 | } |
278 | |
279 | /* --- @l_purge@ --- * |
280 | * |
281 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
282 | * |
283 | * Returns: --- |
284 | * |
285 | * Use: Purges all the free blocks in the buffer, and clears all of |
286 | * the locked memory. Memory is not freed back to the system. |
287 | */ |
288 | |
289 | void l_purge(lmem *lm) |
290 | { |
291 | l_node *l; |
292 | |
293 | l = lm->l; |
294 | while (l) { |
295 | l_node *ll = l->next; |
296 | DESTROY(l); |
297 | l = ll; |
298 | } |
299 | memset(lm->p, 0, lm->sz); |
300 | l = CREATE(l_node); |
301 | l->next = 0; |
302 | l->p = lm->p; |
303 | l->sz = lm->sz; |
304 | l->f = 0; |
305 | lm->l = l; |
306 | lm->free = l->sz; |
307 | } |
308 | |
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309 | /* --- @l_destroy@ --- * |
310 | * |
311 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
312 | * |
313 | * Returns: --- |
314 | * |
315 | * Use: Disposes of a locked memory arena permanently. |
316 | */ |
317 | |
318 | void l_destroy(lmem *lm) |
319 | { |
320 | l_node *l; |
321 | |
322 | l = lm->l; |
323 | while (l) { |
324 | l_node *ll = l->next; |
325 | DESTROY(l); |
326 | l = ll; |
327 | } |
328 | memset(lm->p, 0, lm->sz); |
329 | |
330 | if (lm->f & LF_LOCKED) |
331 | munmap(lm->p, lm->sz); |
332 | else |
333 | free(lm->p); |
334 | } |
335 | |
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336 | /* --- @l_report@ --- * |
337 | * |
338 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
339 | * @dstr *d@ = string to write the error message on |
340 | * |
341 | * Returns: Zero if the buffer is fine, @+1@ if there was a problem |
342 | * getting locked memory but insecure stuff could be allocated, |
343 | * and @-1@ if not even insecure memory could be found. |
344 | * |
345 | * Use: Returns a user-digestable explanation for the state of a |
346 | * locked memory buffer. If the return code is zero, no message |
347 | * is emitted to the string @d@. |
348 | */ |
349 | |
350 | int l_report(lmem *lm, dstr *d) |
351 | { |
352 | int rc; |
353 | if (lm->err) |
354 | dstr_putf(d, lm->emsg, strerror(lm->err)); |
355 | if (!lm->p) |
356 | rc = -1; |
357 | else if (lm->err) |
358 | rc = +1; |
359 | else |
360 | rc = 0; |
361 | return (rc); |
362 | } |
363 | |
364 | /*----- That's all, folks -------------------------------------------------*/ |