t_mprotect.c revision 1.4
1 /* $NetBSD: t_mprotect.c,v 1.4 2016/05/28 14:34:49 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jukka Ruohonen. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include <sys/cdefs.h> 32 __RCSID("$NetBSD: t_mprotect.c,v 1.4 2016/05/28 14:34:49 christos Exp $"); 33 34 #include <sys/param.h> 35 #include <sys/mman.h> 36 #include <sys/sysctl.h> 37 #include <sys/wait.h> 38 39 #include <errno.h> 40 #include <fcntl.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include <atf-c.h> 46 47 #include "../common/exec_prot.h" 48 49 static long page = 0; 50 static int pax_global = -1; 51 static int pax_enabled = -1; 52 static char path[] = "mmap"; 53 54 static void sighandler(int); 55 static bool paxinit(void); 56 static bool paxset(int, int); 57 58 static void 59 sighandler(int signo) 60 { 61 _exit(signo); 62 } 63 64 static bool 65 paxinit(void) 66 { 67 size_t len = sizeof(int); 68 int rv; 69 70 rv = sysctlbyname("security.pax.mprotect.global", 71 &pax_global, &len, NULL, 0); 72 73 if (rv != 0) 74 return false; 75 76 rv = sysctlbyname("security.pax.mprotect.enabled", 77 &pax_enabled, &len, NULL, 0); 78 79 return rv == 0; 80 } 81 82 static bool 83 paxset(int global, int enabled) 84 { 85 size_t len = sizeof(int); 86 int rv; 87 88 rv = sysctlbyname("security.pax.mprotect.global", 89 NULL, NULL, &global, len); 90 91 if (rv != 0) 92 return false; 93 94 rv = sysctlbyname("security.pax.mprotect.enabled", 95 NULL, NULL, &enabled, len); 96 97 if (rv != 0) 98 return false; 99 100 return true; 101 } 102 103 104 ATF_TC_WITH_CLEANUP(mprotect_access); 105 ATF_TC_HEAD(mprotect_access, tc) 106 { 107 atf_tc_set_md_var(tc, "descr", "Test for EACCES from mprotect(2)"); 108 } 109 110 ATF_TC_BODY(mprotect_access, tc) 111 { 112 int prot[2] = { PROT_NONE, PROT_READ }; 113 void *map; 114 size_t i; 115 int fd; 116 117 fd = open(path, O_RDONLY | O_CREAT); 118 ATF_REQUIRE(fd >= 0); 119 120 /* 121 * The call should fail with EACCES if we try to mark 122 * a PROT_NONE or PROT_READ file/section as PROT_WRITE. 123 */ 124 for (i = 0; i < __arraycount(prot); i++) { 125 126 map = mmap(NULL, page, prot[i], MAP_SHARED, fd, 0); 127 128 if (map == MAP_FAILED) 129 continue; 130 131 errno = 0; 132 133 ATF_REQUIRE(mprotect(map, page, PROT_WRITE) != 0); 134 ATF_REQUIRE(errno == EACCES); 135 ATF_REQUIRE(munmap(map, page) == 0); 136 } 137 138 ATF_REQUIRE(close(fd) == 0); 139 } 140 141 ATF_TC_CLEANUP(mprotect_access, tc) 142 { 143 (void)unlink(path); 144 } 145 146 ATF_TC(mprotect_err); 147 ATF_TC_HEAD(mprotect_err, tc) 148 { 149 atf_tc_set_md_var(tc, "descr", "Test error conditions of mprotect(2)"); 150 } 151 152 ATF_TC_BODY(mprotect_err, tc) 153 { 154 errno = 0; 155 156 ATF_REQUIRE(mprotect((char *)-1, 1, PROT_READ) != 0); 157 ATF_REQUIRE(errno == EINVAL); 158 } 159 160 ATF_TC(mprotect_exec); 161 ATF_TC_HEAD(mprotect_exec, tc) 162 { 163 atf_tc_set_md_var(tc, "descr", 164 "Test mprotect(2) executable space protections"); 165 } 166 167 /* 168 * Trivial function -- should fit into a page 169 */ 170 ATF_TC_BODY(mprotect_exec, tc) 171 { 172 pid_t pid; 173 void *map; 174 int sta, xp_support; 175 176 xp_support = exec_prot_support(); 177 178 switch (xp_support) { 179 case NOTIMPL: 180 atf_tc_skip( 181 "Execute protection callback check not implemented"); 182 break; 183 case NO_XP: 184 atf_tc_skip( 185 "Host does not support executable space protection"); 186 break; 187 case PARTIAL_XP: case PERPAGE_XP: default: 188 break; 189 } 190 191 if (!paxinit()) 192 return; 193 if (pax_enabled == 1 && pax_global == 1) 194 atf_tc_skip("PaX MPROTECT restrictions enabled"); 195 196 197 /* 198 * Map a page read/write and copy a trivial assembly function inside. 199 * We will then change the mapping rights: 200 * - first by setting the execution right, and check that we can 201 * call the code found in the allocated page. 202 * - second by removing the execution right. This should generate 203 * a SIGSEGV on architectures that can enforce --x permissions. 204 */ 205 206 map = mmap(NULL, page, PROT_WRITE|PROT_READ, MAP_ANON, -1, 0); 207 ATF_REQUIRE(map != MAP_FAILED); 208 209 memcpy(map, (void *)return_one, 210 (uintptr_t)return_one_end - (uintptr_t)return_one); 211 212 /* give r-x rights then call code in page */ 213 ATF_REQUIRE(mprotect(map, page, PROT_EXEC|PROT_READ) == 0); 214 ATF_REQUIRE(((int (*)(void))map)() == 1); 215 216 /* remove --x right */ 217 ATF_REQUIRE(mprotect(map, page, PROT_READ) == 0); 218 219 pid = fork(); 220 ATF_REQUIRE(pid >= 0); 221 222 if (pid == 0) { 223 ATF_REQUIRE(signal(SIGSEGV, sighandler) != SIG_ERR); 224 ATF_CHECK(((int (*)(void))map)() == 1); 225 _exit(0); 226 } 227 228 (void)wait(&sta); 229 230 ATF_REQUIRE(munmap(map, page) == 0); 231 232 ATF_REQUIRE(WIFEXITED(sta) != 0); 233 234 switch (xp_support) { 235 case PARTIAL_XP: 236 /* Partial protection might fail; skip the test when it does */ 237 if (WEXITSTATUS(sta) != SIGSEGV) { 238 atf_tc_skip("Host only supports " 239 "partial executable space protection"); 240 } 241 break; 242 case PERPAGE_XP: default: 243 /* Per-page --x protection should not fail */ 244 ATF_REQUIRE(WEXITSTATUS(sta) == SIGSEGV); 245 break; 246 } 247 } 248 249 ATF_TC(mprotect_pax); 250 ATF_TC_HEAD(mprotect_pax, tc) 251 { 252 atf_tc_set_md_var(tc, "descr", "PaX restrictions and mprotect(2)"); 253 atf_tc_set_md_var(tc, "require.user", "root"); 254 } 255 256 ATF_TC_BODY(mprotect_pax, tc) 257 { 258 const int prot[4] = { PROT_NONE, PROT_READ, PROT_WRITE }; 259 const char *str = NULL; 260 void *map; 261 size_t i; 262 int rv; 263 264 if (!paxinit() || !paxset(1, 1)) 265 return; 266 267 /* 268 * As noted in the original PaX documentation [1], 269 * the following restrictions should apply: 270 * 271 * (1) creating executable anonymous mappings 272 * 273 * (2) creating executable/writable file mappings 274 * 275 * (3) making a non-executable mapping executable 276 * 277 * (4) making an executable/read-only file mapping 278 * writable except for performing relocations 279 * on an ET_DYN ELF file (non-PIC shared library) 280 * 281 * The following will test only the case (3). 282 * 283 * [1] http://pax.grsecurity.net/docs/mprotect.txt 284 * 285 * (Sun Apr 3 11:06:53 EEST 2011.) 286 */ 287 for (i = 0; i < __arraycount(prot); i++) { 288 289 map = mmap(NULL, page, prot[i], MAP_ANON, -1, 0); 290 291 if (map == MAP_FAILED) 292 continue; 293 294 rv = mprotect(map, 1, prot[i] | PROT_EXEC); 295 296 (void)munmap(map, page); 297 298 if (rv == 0) { 299 str = "non-executable mapping made executable"; 300 goto out; 301 } 302 } 303 304 out: 305 if (pax_global != -1 && pax_enabled != -1) 306 (void)paxset(pax_global, pax_enabled); 307 308 if (str != NULL) 309 atf_tc_fail("%s", str); 310 } 311 312 ATF_TC(mprotect_write); 313 ATF_TC_HEAD(mprotect_write, tc) 314 { 315 atf_tc_set_md_var(tc, "descr", "Test mprotect(2) write protections"); 316 } 317 318 ATF_TC_BODY(mprotect_write, tc) 319 { 320 pid_t pid; 321 void *map; 322 int sta; 323 324 /* 325 * Map a page read/write, change the protection 326 * to read-only with mprotect(2), and try to write 327 * to the page. This should generate a SIGSEGV. 328 */ 329 map = mmap(NULL, page, PROT_WRITE|PROT_READ, MAP_ANON, -1, 0); 330 ATF_REQUIRE(map != MAP_FAILED); 331 332 ATF_REQUIRE(strlcpy(map, "XXX", 3) == 3); 333 ATF_REQUIRE(mprotect(map, page, PROT_READ) == 0); 334 335 pid = fork(); 336 ATF_REQUIRE(pid >= 0); 337 338 if (pid == 0) { 339 ATF_REQUIRE(signal(SIGSEGV, sighandler) != SIG_ERR); 340 ATF_REQUIRE(strlcpy(map, "XXX", 3) == 0); 341 } 342 343 (void)wait(&sta); 344 345 ATF_REQUIRE(WIFEXITED(sta) != 0); 346 ATF_REQUIRE(WEXITSTATUS(sta) == SIGSEGV); 347 ATF_REQUIRE(munmap(map, page) == 0); 348 } 349 350 ATF_TP_ADD_TCS(tp) 351 { 352 page = sysconf(_SC_PAGESIZE); 353 ATF_REQUIRE(page >= 0); 354 355 ATF_TP_ADD_TC(tp, mprotect_access); 356 ATF_TP_ADD_TC(tp, mprotect_err); 357 ATF_TP_ADD_TC(tp, mprotect_exec); 358 ATF_TP_ADD_TC(tp, mprotect_pax); 359 ATF_TP_ADD_TC(tp, mprotect_write); 360 361 return atf_no_error(); 362 } 363
Indexes created Tue Sep 23 02:09:52 GMT 2025