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