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