359df778 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: lmem.c,v 1.1 1999/12/22 16:02:52 mdw Exp $ |
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 $ |
33 | * Revision 1.1 1999/12/22 16:02:52 mdw |
34 | * Interface to allocating `locked' memory (which isn't paged out). |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "config.h" |
41 | |
42 | #include <assert.h> |
43 | #include <errno.h> |
44 | #include <stdio.h> |
45 | #include <stdlib.h> |
46 | #include <string.h> |
47 | |
48 | #include <sys/types.h> |
49 | #include <unistd.h> |
50 | |
51 | #ifdef HAVE_MLOCK |
52 | # include <sys/mman.h> |
53 | #endif |
54 | |
55 | #include <mLib/dstr.h> |
56 | #include <mLib/sub.h> |
57 | |
58 | #include "lmem.h" |
59 | |
60 | /*----- Main code ---------------------------------------------------------*/ |
61 | |
62 | /* --- @l_init@ --- * |
63 | * |
64 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
65 | * @size_t sz@ = size of locked memory area requested |
66 | * |
67 | * Returns: Zero if everything is fine, @+1@ if some insecure memory was |
68 | * allocated, and @-1@ if everything went horribly wrong. |
69 | * |
70 | * Use: Initializes the locked memory manager. This function is safe |
71 | * to call in a privileged program; privileges should usually be |
72 | * dropped after allocating the locked memory block. |
73 | * |
74 | * You must call @sub_init@ before allocating locked memory |
75 | * buffers. |
76 | */ |
77 | |
78 | int l_init(lmem *lm, size_t sz) |
79 | { |
80 | char *p; |
81 | int rc = 0; |
82 | l_node *l; |
83 | |
84 | /* --- Preliminaries --- */ |
85 | |
86 | lm->err = 0; |
87 | |
88 | /* --- Try making a secure locked passphrase buffer --- * |
89 | * |
90 | * Drop privileges before emitting diagnostic messages. |
91 | */ |
92 | |
93 | #ifdef HAVE_MLOCK |
94 | |
95 | /* --- Memory-map a page from somewhere --- */ |
96 | |
97 | # ifdef MAP_ANON |
98 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); |
99 | # else |
100 | { |
101 | int fd; |
102 | if ((fd = open("/dev/zero", O_RDWR)) >= 0) { |
103 | p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); |
104 | close(fd); |
105 | } |
106 | } |
107 | # endif |
108 | |
109 | /* --- Lock the page in memory --- * |
110 | * |
111 | * Why does @mmap@ return such a stupid result if it fails? |
112 | */ |
113 | |
114 | if (p == 0 || p == MAP_FAILED) { |
115 | lm->emsg = "couldn't map locked memory area: %s"; |
116 | lm->err = errno; |
117 | p = 0; |
118 | } else if (mlock(p, sz)) { |
119 | lm->emsg = "error locking memory area: %s"; |
120 | lm->err = errno; |
121 | munmap(p, sz); |
122 | p = 0; |
123 | } |
124 | |
125 | #endif |
126 | |
127 | /* --- Make a standard passphrase buffer --- */ |
128 | |
129 | #ifdef HAVE_MLOCK |
130 | if (!p) |
131 | #else |
132 | ll->err = 0; |
133 | ll->emsg = "locked memory not available on this system"; |
134 | #endif |
135 | { |
136 | if ((p = malloc(sz)) == 0) { |
137 | lm->emsg = "not enough standard memory!"; |
138 | lm->err = ENOMEM; |
139 | return (-1); |
140 | } |
141 | rc = +1; |
142 | } |
143 | |
144 | /* --- Initialize the buffer --- */ |
145 | |
146 | lm->sz = lm->free = sz; |
147 | lm->p = p; |
148 | |
149 | /* --- Initialize the free list --- */ |
150 | |
151 | l = CREATE(l_node); |
152 | l->next = 0; |
153 | l->p = p; |
154 | l->sz = sz; |
155 | l->f = 0; |
156 | lm->l = l; |
157 | |
158 | /* --- Done --- */ |
159 | |
160 | return (rc); |
161 | } |
162 | |
163 | /* --- @l_alloc@ --- * |
164 | * |
165 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
166 | * @size_t sz@ = size requested |
167 | * |
168 | * Returns: Pointer to allocated memory. |
169 | * |
170 | * Use: Allocates @sz@ bytes of locked memory. |
171 | */ |
172 | |
173 | void *l_alloc(lmem *lm, size_t sz) |
174 | { |
175 | l_node *l; |
176 | |
177 | sz = (sz + 3u) & ~3u; |
178 | for (l = lm->l; l; l = l->next) { |
179 | if (l->f & LF_ALLOC) |
180 | continue; |
181 | if (l->sz < sz) |
182 | continue; |
183 | l->f |= LF_ALLOC; |
184 | if (l->sz > sz) { |
185 | l_node *n = CREATE(l_node); |
186 | n->next = l->next; |
187 | n->p = l->p + sz; |
188 | n->sz = l->sz - sz; |
189 | l->sz = sz; |
190 | n->f = 0; |
191 | l->next = n; |
192 | } |
193 | assert(((void)"Locked buffer space has vanished", lm->free >= sz)); |
194 | lm->free -= sz; |
195 | return (l->p); |
196 | } |
197 | return (0); |
198 | } |
199 | |
200 | /* --- @l_free@ --- * |
201 | * |
202 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
203 | * @void *p@ = pointer to block |
204 | * |
205 | * Returns: --- |
206 | * |
207 | * Use: Releases a block of locked memory. |
208 | */ |
209 | |
210 | void l_free(lmem *lm, void *p) |
211 | { |
212 | l_node *l; |
213 | l_node *ll = 0; |
214 | |
215 | for (l = lm->l; l; l = l->next) { |
216 | size_t sz; |
217 | |
218 | /* --- If this isn't the block, skip it --- */ |
219 | |
220 | if (l->p != p) { |
221 | ll = l; |
222 | continue; |
223 | } |
224 | assert(((void)"Block is already free", l->f & LF_ALLOC)); |
225 | |
226 | /* --- Coalesce with adjacent free blocks --- */ |
227 | |
228 | l->f &= ~LF_ALLOC; |
229 | sz = l->sz; |
230 | memset(p, 0, sz); |
231 | |
232 | if (ll && !(ll->f & LF_ALLOC)) { |
233 | assert(((void)"Previous block doesn't fit", ll->p + ll->sz == p)); |
234 | ll->sz += sz; |
235 | ll->next = l->next; |
236 | DESTROY(l); |
237 | l = ll; |
238 | } |
239 | |
240 | ll = l->next; |
241 | if (ll && !(ll->f & LF_ALLOC)) { |
242 | assert(((void)"Next block doesn't fit", ll->p == l->p + l->sz)); |
243 | l->sz += ll->sz; |
244 | l->next = ll->next; |
245 | DESTROY(ll); |
246 | } |
247 | |
248 | lm->free += sz; |
249 | assert(((void)"Free lunch", lm->free <= lm->sz)); |
250 | return; |
251 | } |
252 | assert(((void)"Not a locked block", 0)); |
253 | } |
254 | |
255 | /* --- @l_purge@ --- * |
256 | * |
257 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
258 | * |
259 | * Returns: --- |
260 | * |
261 | * Use: Purges all the free blocks in the buffer, and clears all of |
262 | * the locked memory. Memory is not freed back to the system. |
263 | */ |
264 | |
265 | void l_purge(lmem *lm) |
266 | { |
267 | l_node *l; |
268 | |
269 | l = lm->l; |
270 | while (l) { |
271 | l_node *ll = l->next; |
272 | DESTROY(l); |
273 | l = ll; |
274 | } |
275 | memset(lm->p, 0, lm->sz); |
276 | l = CREATE(l_node); |
277 | l->next = 0; |
278 | l->p = lm->p; |
279 | l->sz = lm->sz; |
280 | l->f = 0; |
281 | lm->l = l; |
282 | lm->free = l->sz; |
283 | } |
284 | |
285 | /* --- @l_report@ --- * |
286 | * |
287 | * Arguments: @lmem *lm@ = pointer to locked memory descriptor |
288 | * @dstr *d@ = string to write the error message on |
289 | * |
290 | * Returns: Zero if the buffer is fine, @+1@ if there was a problem |
291 | * getting locked memory but insecure stuff could be allocated, |
292 | * and @-1@ if not even insecure memory could be found. |
293 | * |
294 | * Use: Returns a user-digestable explanation for the state of a |
295 | * locked memory buffer. If the return code is zero, no message |
296 | * is emitted to the string @d@. |
297 | */ |
298 | |
299 | int l_report(lmem *lm, dstr *d) |
300 | { |
301 | int rc; |
302 | if (lm->err) |
303 | dstr_putf(d, lm->emsg, strerror(lm->err)); |
304 | if (!lm->p) |
305 | rc = -1; |
306 | else if (lm->err) |
307 | rc = +1; |
308 | else |
309 | rc = 0; |
310 | return (rc); |
311 | } |
312 | |
313 | /*----- That's all, folks -------------------------------------------------*/ |