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