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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: lmem.c,v 1.4 2002/01/24 22:26:11 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 1.4 2002/01/24 22:26:11 mdw |
34 | * Fix build failure when @mlock@ not available. |
35 | * |
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36 | * Revision 1.3 2000/07/29 21:58:15 mdw |
37 | * (l_destroy): New function for destroying locked memory blocks. |
38 | * |
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39 | * Revision 1.2 2000/06/17 11:29:20 mdw |
40 | * Add arena support. |
41 | * |
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42 | * Revision 1.1 1999/12/22 16:02:52 mdw |
43 | * Interface to allocating `locked' memory (which isn't paged out). |
44 | * |
45 | */ |
46 | |
47 | /*----- Header files ------------------------------------------------------*/ |
48 | |
49 | #include "config.h" |
50 | |
51 | #include <assert.h> |
52 | #include <errno.h> |
53 | #include <stdio.h> |
54 | #include <stdlib.h> |
55 | #include <string.h> |
56 | |
57 | #include <sys/types.h> |
58 | #include <unistd.h> |
59 | |
60 | #ifdef HAVE_MLOCK |
61 | # include <sys/mman.h> |
62 | #endif |
63 | |
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64 | #include <mLib/arena.h> |
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65 | #include <mLib/dstr.h> |
66 | #include <mLib/sub.h> |
67 | |
68 | #include "lmem.h" |
69 | |
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70 | /*----- Arena operations --------------------------------------------------*/ |
71 | |
72 | static void *aalloc(arena *a, size_t sz) { return l_alloc((lmem *)a, sz); } |
73 | static void afree(arena *a, void *p) { l_free((lmem *)a, p); } |
74 | static void apurge(arena *a) { l_purge((lmem *)a); } |
75 | |
76 | static arena_ops l_ops = { aalloc, arena_fakerealloc, afree, apurge }; |
77 | |
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78 | /*----- Main code ---------------------------------------------------------*/ |
79 | |
80 | /* --- @l_init@ --- * |
81 | * |
82 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
83 | * @size_t sz@ = size of locked memory area requested |
84 | * |
85 | * Returns: Zero if everything is fine, @+1@ if some insecure memory was |
86 | * allocated, and @-1@ if everything went horribly wrong. |
87 | * |
88 | * Use: Initializes the locked memory manager. This function is safe |
89 | * to call in a privileged program; privileges should usually be |
90 | * dropped after allocating the locked memory block. |
91 | * |
92 | * You must call @sub_init@ before allocating locked memory |
93 | * buffers. |
94 | */ |
95 | |
96 | int l_init(lmem *lm, size_t sz) |
97 | { |
98 | char *p; |
99 | int rc = 0; |
100 | l_node *l; |
101 | |
102 | /* --- Preliminaries --- */ |
103 | |
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104 | lm->a.ops = &l_ops; |
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105 | lm->err = 0; |
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106 | lm->f = 0; |
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107 | |
108 | /* --- Try making a secure locked passphrase buffer --- * |
109 | * |
110 | * Drop privileges before emitting diagnostic messages. |
111 | */ |
112 | |
113 | #ifdef HAVE_MLOCK |
114 | |
115 | /* --- Memory-map a page from somewhere --- */ |
116 | |
117 | # ifdef MAP_ANON |
118 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); |
119 | # else |
120 | { |
121 | int fd; |
122 | if ((fd = open("/dev/zero", O_RDWR)) >= 0) { |
123 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); |
124 | close(fd); |
125 | } |
126 | } |
127 | # endif |
128 | |
129 | /* --- Lock the page in memory --- * |
130 | * |
131 | * Why does @mmap@ return such a stupid result if it fails? |
132 | */ |
133 | |
134 | if (p == 0 || p == MAP_FAILED) { |
135 | lm->emsg = "couldn't map locked memory area: %s"; |
136 | lm->err = errno; |
137 | p = 0; |
138 | } else if (mlock(p, sz)) { |
139 | lm->emsg = "error locking memory area: %s"; |
140 | lm->err = errno; |
141 | munmap(p, sz); |
142 | p = 0; |
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143 | } else |
144 | lm->f |= LF_LOCKED; |
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145 | |
146 | #endif |
147 | |
148 | /* --- Make a standard passphrase buffer --- */ |
149 | |
150 | #ifdef HAVE_MLOCK |
151 | if (!p) |
152 | #else |
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153 | lm->err = 0; |
154 | lm->emsg = "locked memory not available on this system"; |
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155 | #endif |
156 | { |
157 | if ((p = malloc(sz)) == 0) { |
158 | lm->emsg = "not enough standard memory!"; |
159 | lm->err = ENOMEM; |
160 | return (-1); |
161 | } |
162 | rc = +1; |
163 | } |
164 | |
165 | /* --- Initialize the buffer --- */ |
166 | |
167 | lm->sz = lm->free = sz; |
168 | lm->p = p; |
169 | |
170 | /* --- Initialize the free list --- */ |
171 | |
172 | l = CREATE(l_node); |
173 | l->next = 0; |
174 | l->p = p; |
175 | l->sz = sz; |
176 | l->f = 0; |
177 | lm->l = l; |
178 | |
179 | /* --- Done --- */ |
180 | |
181 | return (rc); |
182 | } |
183 | |
184 | /* --- @l_alloc@ --- * |
185 | * |
186 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
187 | * @size_t sz@ = size requested |
188 | * |
189 | * Returns: Pointer to allocated memory. |
190 | * |
191 | * Use: Allocates @sz@ bytes of locked memory. |
192 | */ |
193 | |
194 | void *l_alloc(lmem *lm, size_t sz) |
195 | { |
196 | l_node *l; |
197 | |
198 | sz = (sz + 3u) & ~3u; |
199 | for (l = lm->l; l; l = l->next) { |
200 | if (l->f & LF_ALLOC) |
201 | continue; |
202 | if (l->sz < sz) |
203 | continue; |
204 | l->f |= LF_ALLOC; |
205 | if (l->sz > sz) { |
206 | l_node *n = CREATE(l_node); |
207 | n->next = l->next; |
208 | n->p = l->p + sz; |
209 | n->sz = l->sz - sz; |
210 | l->sz = sz; |
211 | n->f = 0; |
212 | l->next = n; |
213 | } |
214 | assert(((void)"Locked buffer space has vanished", lm->free >= sz)); |
215 | lm->free -= sz; |
216 | return (l->p); |
217 | } |
218 | return (0); |
219 | } |
220 | |
221 | /* --- @l_free@ --- * |
222 | * |
223 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
224 | * @void *p@ = pointer to block |
225 | * |
226 | * Returns: --- |
227 | * |
228 | * Use: Releases a block of locked memory. |
229 | */ |
230 | |
231 | void l_free(lmem *lm, void *p) |
232 | { |
233 | l_node *l; |
234 | l_node *ll = 0; |
235 | |
236 | for (l = lm->l; l; l = l->next) { |
237 | size_t sz; |
238 | |
239 | /* --- If this isn't the block, skip it --- */ |
240 | |
241 | if (l->p != p) { |
242 | ll = l; |
243 | continue; |
244 | } |
245 | assert(((void)"Block is already free", l->f & LF_ALLOC)); |
246 | |
247 | /* --- Coalesce with adjacent free blocks --- */ |
248 | |
249 | l->f &= ~LF_ALLOC; |
250 | sz = l->sz; |
251 | memset(p, 0, sz); |
252 | |
253 | if (ll && !(ll->f & LF_ALLOC)) { |
254 | assert(((void)"Previous block doesn't fit", ll->p + ll->sz == p)); |
255 | ll->sz += sz; |
256 | ll->next = l->next; |
257 | DESTROY(l); |
258 | l = ll; |
259 | } |
260 | |
261 | ll = l->next; |
262 | if (ll && !(ll->f & LF_ALLOC)) { |
263 | assert(((void)"Next block doesn't fit", ll->p == l->p + l->sz)); |
264 | l->sz += ll->sz; |
265 | l->next = ll->next; |
266 | DESTROY(ll); |
267 | } |
268 | |
269 | lm->free += sz; |
270 | assert(((void)"Free lunch", lm->free <= lm->sz)); |
271 | return; |
272 | } |
273 | assert(((void)"Not a locked block", 0)); |
274 | } |
275 | |
276 | /* --- @l_purge@ --- * |
277 | * |
278 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
279 | * |
280 | * Returns: --- |
281 | * |
282 | * Use: Purges all the free blocks in the buffer, and clears all of |
283 | * the locked memory. Memory is not freed back to the system. |
284 | */ |
285 | |
286 | void l_purge(lmem *lm) |
287 | { |
288 | l_node *l; |
289 | |
290 | l = lm->l; |
291 | while (l) { |
292 | l_node *ll = l->next; |
293 | DESTROY(l); |
294 | l = ll; |
295 | } |
296 | memset(lm->p, 0, lm->sz); |
297 | l = CREATE(l_node); |
298 | l->next = 0; |
299 | l->p = lm->p; |
300 | l->sz = lm->sz; |
301 | l->f = 0; |
302 | lm->l = l; |
303 | lm->free = l->sz; |
304 | } |
305 | |
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306 | /* --- @l_destroy@ --- * |
307 | * |
308 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
309 | * |
310 | * Returns: --- |
311 | * |
312 | * Use: Disposes of a locked memory arena permanently. |
313 | */ |
314 | |
315 | void l_destroy(lmem *lm) |
316 | { |
317 | l_node *l; |
318 | |
319 | l = lm->l; |
320 | while (l) { |
321 | l_node *ll = l->next; |
322 | DESTROY(l); |
323 | l = ll; |
324 | } |
325 | memset(lm->p, 0, lm->sz); |
326 | |
327 | if (lm->f & LF_LOCKED) |
328 | munmap(lm->p, lm->sz); |
329 | else |
330 | free(lm->p); |
331 | } |
332 | |
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333 | /* --- @l_report@ --- * |
334 | * |
335 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
336 | * @dstr *d@ = string to write the error message on |
337 | * |
338 | * Returns: Zero if the buffer is fine, @+1@ if there was a problem |
339 | * getting locked memory but insecure stuff could be allocated, |
340 | * and @-1@ if not even insecure memory could be found. |
341 | * |
342 | * Use: Returns a user-digestable explanation for the state of a |
343 | * locked memory buffer. If the return code is zero, no message |
344 | * is emitted to the string @d@. |
345 | */ |
346 | |
347 | int l_report(lmem *lm, dstr *d) |
348 | { |
349 | int rc; |
350 | if (lm->err) |
351 | dstr_putf(d, lm->emsg, strerror(lm->err)); |
352 | if (!lm->p) |
353 | rc = -1; |
354 | else if (lm->err) |
355 | rc = +1; |
356 | else |
357 | rc = 0; |
358 | return (rc); |
359 | } |
360 | |
361 | /*----- That's all, folks -------------------------------------------------*/ |