Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 | /*
* random.c -- A strong random number generator
*
* Version 1.89, last modified 19-Sep-99
*
* Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
* rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU General Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
/*
* (now, with legal B.S. out of the way.....)
*
* This routine gathers environmental noise from device drivers, etc.,
* and returns good random numbers, suitable for cryptographic use.
* Besides the obvious cryptographic uses, these numbers are also good
* for seeding TCP sequence numbers, and other places where it is
* desirable to have numbers which are not only random, but hard to
* predict by an attacker.
*
* Theory of operation
* ===================
*
* Computers are very predictable devices. Hence it is extremely hard
* to produce truly random numbers on a computer --- as opposed to
* pseudo-random numbers, which can easily generated by using a
* algorithm. Unfortunately, it is very easy for attackers to guess
* the sequence of pseudo-random number generators, and for some
* applications this is not acceptable. So instead, we must try to
* gather "environmental noise" from the computer's environment, which
* must be hard for outside attackers to observe, and use that to
* generate random numbers. In a Unix environment, this is best done
* from inside the kernel.
*
* Sources of randomness from the environment include inter-keyboard
* timings, inter-interrupt timings from some interrupts, and other
* events which are both (a) non-deterministic and (b) hard for an
* outside observer to measure. Randomness from these sources are
* added to an "entropy pool", which is mixed using a CRC-like function.
* This is not cryptographically strong, but it is adequate assuming
* the randomness is not chosen maliciously, and it is fast enough that
* the overhead of doing it on every interrupt is very reasonable.
* As random bytes are mixed into the entropy pool, the routines keep
* an *estimate* of how many bits of randomness have been stored into
* the random number generator's internal state.
*
* When random bytes are desired, they are obtained by taking the SHA
* hash of the contents of the "entropy pool". The SHA hash avoids
* exposing the internal state of the entropy pool. It is believed to
* be computationally infeasible to derive any useful information
* about the input of SHA from its output. Even if it is possible to
* analyze SHA in some clever way, as long as the amount of data
* returned from the generator is less than the inherent entropy in
* the pool, the output data is totally unpredictable. For this
* reason, the routine decreases its internal estimate of how many
* bits of "true randomness" are contained in the entropy pool as it
* outputs random numbers.
*
* If this estimate goes to zero, the routine can still generate
* random numbers; however, an attacker may (at least in theory) be
* able to infer the future output of the generator from prior
* outputs. This requires successful cryptanalysis of SHA, which is
* not believed to be feasible, but there is a remote possibility.
* Nonetheless, these numbers should be useful for the vast majority
* of purposes.
*
* Exported interfaces ---- output
* ===============================
*
* There are three exported interfaces; the first is one designed to
* be used from within the kernel:
*
* void get_random_bytes(void *buf, int nbytes);
*
* This interface will return the requested number of random bytes,
* and place it in the requested buffer.
*
* The two other interfaces are two character devices /dev/random and
* /dev/urandom. /dev/random is suitable for use when very high
* quality randomness is desired (for example, for key generation or
* one-time pads), as it will only return a maximum of the number of
* bits of randomness (as estimated by the random number generator)
* contained in the entropy pool.
*
* The /dev/urandom device does not have this limit, and will return
* as many bytes as are requested. As more and more random bytes are
* requested without giving time for the entropy pool to recharge,
* this will result in random numbers that are merely cryptographically
* strong. For many applications, however, this is acceptable.
*
* Exported interfaces ---- input
* ==============================
*
* The current exported interfaces for gathering environmental noise
* from the devices are:
*
* void add_keyboard_randomness(unsigned char scancode);
* void add_mouse_randomness(__u32 mouse_data);
* void add_interrupt_randomness(int irq);
* void add_blkdev_randomness(int irq);
*
* add_keyboard_randomness() uses the inter-keypress timing, as well as the
* scancode as random inputs into the "entropy pool".
*
* add_mouse_randomness() uses the mouse interrupt timing, as well as
* the reported position of the mouse from the hardware.
*
* add_interrupt_randomness() uses the inter-interrupt timing as random
* inputs to the entropy pool. Note that not all interrupts are good
* sources of randomness! For example, the timer interrupts is not a
* good choice, because the periodicity of the interrupts is too
* regular, and hence predictable to an attacker. Disk interrupts are
* a better measure, since the timing of the disk interrupts are more
* unpredictable.
*
* add_blkdev_randomness() times the finishing time of block requests.
*
* All of these routines try to estimate how many bits of randomness a
* particular randomness source. They do this by keeping track of the
* first and second order deltas of the event timings.
*
* Ensuring unpredictability at system startup
* ============================================
*
* When any operating system starts up, it will go through a sequence
* of actions that are fairly predictable by an adversary, especially
* if the start-up does not involve interaction with a human operator.
* This reduces the actual number of bits of unpredictability in the
* entropy pool below the value in entropy_count. In order to
* counteract this effect, it helps to carry information in the
* entropy pool across shut-downs and start-ups. To do this, put the
* following lines an appropriate script which is run during the boot
* sequence:
*
* echo "Initializing random number generator..."
* random_seed=/var/run/random-seed
* # Carry a random seed from start-up to start-up
* # Load and then save 512 bytes, which is the size of the entropy pool
* if [ -f $random_seed ]; then
* cat $random_seed >/dev/urandom
* fi
* dd if=/dev/urandom of=$random_seed count=1
* chmod 600 $random_seed
*
* and the following lines in an appropriate script which is run as
* the system is shutdown:
*
* # Carry a random seed from shut-down to start-up
* # Save 512 bytes, which is the size of the entropy pool
* echo "Saving random seed..."
* random_seed=/var/run/random-seed
* dd if=/dev/urandom of=$random_seed count=1
* chmod 600 $random_seed
*
* For example, on most modern systems using the System V init
* scripts, such code fragments would be found in
* /etc/rc.d/init.d/random. On older Linux systems, the correct script
* location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
*
* Effectively, these commands cause the contents of the entropy pool
* to be saved at shut-down time and reloaded into the entropy pool at
* start-up. (The 'dd' in the addition to the bootup script is to
* make sure that /etc/random-seed is different for every start-up,
* even if the system crashes without executing rc.0.) Even with
* complete knowledge of the start-up activities, predicting the state
* of the entropy pool requires knowledge of the previous history of
* the system.
*
* Configuring the /dev/random driver under Linux
* ==============================================
*
* The /dev/random driver under Linux uses minor numbers 8 and 9 of
* the /dev/mem major number (#1). So if your system does not have
* /dev/random and /dev/urandom created already, they can be created
* by using the commands:
*
* mknod /dev/random c 1 8
* mknod /dev/urandom c 1 9
*
* Acknowledgements:
* =================
*
* Ideas for constructing this random number generator were derived
* from Pretty Good Privacy's random number generator, and from private
* discussions with Phil Karn. Colin Plumb provided a faster random
* number generator, which speed up the mixing function of the entropy
* pool, taken from PGPfone. Dale Worley has also contributed many
* useful ideas and suggestions to improve this driver.
*
* Any flaws in the design are solely my responsibility, and should
* not be attributed to the Phil, Colin, or any of authors of PGP.
*
* The code for SHA transform was taken from Peter Gutmann's
* implementation, which has been placed in the public domain.
* The code for MD5 transform was taken from Colin Plumb's
* implementation, which has been placed in the public domain.
* The MD5 cryptographic checksum was devised by Ronald Rivest, and is
* documented in RFC 1321, "The MD5 Message Digest Algorithm".
*
* Further background information on this topic may be obtained from
* RFC 1750, "Randomness Recommendations for Security", by Donald
* Eastlake, Steve Crocker, and Jeff Schiller.
*/
#include <linux/utsname.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
/*
* Configuration information
*/
#define DEFAULT_POOL_SIZE 512
#define SECONDARY_POOL_SIZE 128
#define BATCH_ENTROPY_SIZE 256
#define USE_SHA
/*
* The minimum number of bits of entropy before we wake up a read on
* /dev/random. Should always be at least 8, or at least 1 byte.
*/
static int random_read_wakeup_thresh = 8;
/*
* If the entropy count falls under this number of bits, then we
* should wake up processes which are selecting or polling on write
* access to /dev/random.
*/
static int random_write_wakeup_thresh = 128;
/*
* A pool of size POOLWORDS is stirred with a primitive polynomial
* of degree POOLWORDS over GF(2). The taps for various sizes are
* defined below. They are chosen to be evenly spaced (minimum RMS
* distance from evenly spaced; the numbers in the comments are a
* scaled squared error sum) except for the last tap, which is 1 to
* get the twisting happening as fast as possible.
*/
static struct poolinfo {
int poolwords;
int tap1, tap2, tap3, tap4, tap5;
} poolinfo_table[] = {
/* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
{ 2048, 1638, 1231, 819, 411, 1 },
/* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
{ 1024, 817, 615, 412, 204, 1 },
#if 0 /* Alternate polynomial */
/* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
{ 1024, 819, 616, 410, 207, 2 },
#endif
/* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
{ 512, 411, 308, 208, 104, 1 },
#if 0 /* Alternates */
/* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
{ 512, 409, 307, 206, 102, 2 },
/* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
{ 512, 409, 309, 205, 103, 2 },
#endif
/* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
{ 256, 205, 155, 101, 52, 1 },
/* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */
{ 128, 103, 76, 51, 25, 1 },
#if 0 /* Alternate polynomial */
/* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
{ 128, 103, 78, 51, 27, 2 },
#endif
/* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
{ 64, 52, 39, 26, 14, 1 },
/* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */
{ 32, 26, 20, 14, 7, 1 },
{ 0, 0, 0, 0, 0, 0 },
};
/*
* For the purposes of better mixing, we use the CRC-32 polynomial as
* well to make a twisted Generalized Feedback Shift Reigster
*
* (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM
* Transactions on Modeling and Computer Simulation 2(3):179-194.
* Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators
* II. ACM Transactions on Mdeling and Computer Simulation 4:254-266)
*
* Thanks to Colin Plumb for suggesting this.
*
* We have not analyzed the resultant polynomial to prove it primitive;
* in fact it almost certainly isn't. Nonetheless, the irreducible factors
* of a random large-degree polynomial over GF(2) are more than large enough
* that periodicity is not a concern.
*
* The input hash is much less sensitive than the output hash. All
* that we want of it is that it be a good non-cryptographic hash;
* i.e. it not produce collisions when fed "random" data of the sort
* we expect to see. As long as the pool state differs for different
* inputs, we have preserved the input entropy and done a good job.
* The fact that an intelligent attacker can construct inputs that
* will produce controlled alterations to the pool's state is not
* important because we don't consider such inputs to contribute any
* randomness. The only property we need with respect to them is that
* the attacker can't increase his/her knowledge of the pool's state.
* Since all additions are reversible (knowing the final state and the
* input, you can reconstruct the initial state), if an attacker has
* any uncertainty about the initial state, he/she can only shuffle
* that uncertainty about, but never cause any collisions (which would
* decrease the uncertainty).
*
* The chosen system lets the state of the pool be (essentially) the input
* modulo the generator polymnomial. Now, for random primitive polynomials,
* this is a universal class of hash functions, meaning that the chance
* of a collision is limited by the attacker's knowledge of the generator
* polynomail, so if it is chosen at random, an attacker can never force
* a collision. Here, we use a fixed polynomial, but we *can* assume that
* ###--> it is unknown to the processes generating the input entropy. <-###
* Because of this important property, this is a good, collision-resistant
* hash; hash collisions will occur no more often than chance.
*/
/*
* Linux 2.2 compatibility
*/
#ifndef DECLARE_WAITQUEUE
#define DECLARE_WAITQUEUE(WAIT, PTR) struct wait_queue WAIT = { PTR, NULL }
#endif
#ifndef DECLARE_WAIT_QUEUE_HEAD
#define DECLARE_WAIT_QUEUE_HEAD(WAIT) struct wait_queue *WAIT
#endif
/*
* Static global variables
*/
static struct entropy_store *random_state; /* The default global store */
static struct entropy_store *sec_random_state; /* secondary store */
static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
/*
* Forward procedure declarations
*/
#ifdef CONFIG_SYSCTL
static void sysctl_init_random(struct entropy_store *random_state);
#endif
/*****************************************************************
*
* Utility functions, with some ASM defined functions for speed
* purposes
*
*****************************************************************/
#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
/*
* Unfortunately, while the GCC optimizer for the i386 understands how
* to optimize a static rotate left of x bits, it doesn't know how to
* deal with a variable rotate of x bits. So we use a bit of asm magic.
*/
#if (!defined (__i386__))
extern inline __u32 rotate_left(int i, __u32 word)
{
return (word << i) | (word >> (32 - i));
}
#else
extern inline __u32 rotate_left(int i, __u32 word)
{
__asm__("roll %%cl,%0"
:"=r" (word)
:"0" (word),"c" (i));
return word;
}
#endif
/*
* More asm magic....
*
* For entropy estimation, we need to do an integral base 2
* logarithm.
*
* Note the "12bits" suffix - this is used for numbers between
* 0 and 4095 only. This allows a few shortcuts.
*/
#if 0 /* Slow but clear version */
static inline __u32 int_ln_12bits(__u32 word)
{
__u32 nbits = 0;
while (word >>= 1)
nbits++;
return nbits;
}
#else /* Faster (more clever) version, courtesy Colin Plumb */
static inline __u32 int_ln_12bits(__u32 word)
{
/* Smear msbit right to make an n-bit mask */
word |= word >> 8;
word |= word >> 4;
word |= word >> 2;
word |= word >> 1;
/* Remove one bit to make this a logarithm */
word >>= 1;
/* Count the bits set in the word */
word -= (word >> 1) & 0x555;
word = (word & 0x333) + ((word >> 2) & 0x333);
word += (word >> 4);
word += (word >> 8);
return word & 15;
}
#endif
/**********************************************************************
*
* OS independent entropy store. Here are the functions which handle
* storing entropy in an entropy pool.
*
**********************************************************************/
struct entropy_store {
unsigned add_ptr;
int entropy_count;
int input_rotate;
int extract_count;
struct poolinfo poolinfo;
__u32 *pool;
};
/*
* Initialize the entropy store. The input argument is the size of
* the random pool.
*
* Returns an negative error if there is a problem.
*/
static int create_entropy_store(int size, struct entropy_store **ret_bucket)
{
struct entropy_store *r;
struct poolinfo *p;
int poolwords;
poolwords = (size + 3) / 4; /* Convert bytes->words */
/* The pool size must be a multiple of 16 32-bit words */
poolwords = ((poolwords + 15) / 16) * 16;
for (p = poolinfo_table; p->poolwords; p++) {
if (poolwords == p->poolwords)
break;
}
if (p->poolwords == 0)
return -EINVAL;
r = kmalloc(sizeof(struct entropy_store), GFP_KERNEL);
if (!r)
return -ENOMEM;
memset (r, 0, sizeof(struct entropy_store));
r->poolinfo = *p;
r->pool = kmalloc(poolwords*4, GFP_KERNEL);
if (!r->pool) {
kfree(r);
return -ENOMEM;
}
memset(r->pool, 0, poolwords*4);
*ret_bucket = r;
return 0;
}
/* Clear the entropy pool and associated counters. */
static void clear_entropy_store(struct entropy_store *r)
{
r->add_ptr = 0;
r->entropy_count = 0;
r->input_rotate = 0;
r->extract_count = 0;
memset(r->pool, 0, r->poolinfo.poolwords*4);
}
static void free_entropy_store(struct entropy_store *r)
{
if (r->pool)
kfree(r->pool);
kfree(r);
}
/*
* This function adds a byte into the entropy "pool". It does not
* update the entropy estimate. The caller should call
* credit_entropy_store if this is appropriate.
*
* The pool is stirred with a primitive polynomial of the appropriate
* degree, and then twisted. We twist by three bits at a time because
* it's cheap to do so and helps slightly in the expected case where
* the entropy is concentrated in the low-order bits.
*/
static void add_entropy_words(struct entropy_store *r, const __u32 *in,
int num)
{
static __u32 const twist_table[8] = {
0, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
unsigned i;
int new_rotate;
__u32 w;
while (num--) {
w = rotate_left(r->input_rotate, *in);
i = r->add_ptr = (r->add_ptr - 1) & (r->poolinfo.poolwords-1);
/*
* Normally, we add 7 bits of rotation to the pool.
* At the beginning of the pool, add an extra 7 bits
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
new_rotate = r->input_rotate + 14;
if (i)
new_rotate = r->input_rotate + 7;
r->input_rotate = new_rotate & 31;
/* XOR in the various taps */
w ^= r->pool[(i+r->poolinfo.tap1)&(r->poolinfo.poolwords-1)];
w ^= r->pool[(i+r->poolinfo.tap2)&(r->poolinfo.poolwords-1)];
w ^= r->pool[(i+r->poolinfo.tap3)&(r->poolinfo.poolwords-1)];
w ^= r->pool[(i+r->poolinfo.tap4)&(r->poolinfo.poolwords-1)];
w ^= r->pool[(i+r->poolinfo.tap5)&(r->poolinfo.poolwords-1)];
w ^= r->pool[i];
r->pool[i] = (w >> 3) ^ twist_table[w & 7];
}
}
/*
* Credit (or debit) the entropy store with n bits of entropy
*/
static void credit_entropy_store(struct entropy_store *r, int num)
{
int max_entropy = r->poolinfo.poolwords*32;
if (r->entropy_count + num < 0)
r->entropy_count = 0;
else if (r->entropy_count + num > max_entropy)
r->entropy_count = max_entropy;
else
r->entropy_count = r->entropy_count + num;
}
/**********************************************************************
*
* Entropy batch input management
*
* We batch entropy to be added to avoid increasing interrupt latency
*
**********************************************************************/
static __u32 *batch_entropy_pool;
static int *batch_entropy_credit;
static int batch_max;
static int batch_head, batch_tail;
static struct tq_struct batch_tqueue;
static void batch_entropy_process(void *private_);
/* note: the size must be a power of 2 */
static int __init batch_entropy_init(int size, struct entropy_store *r)
{
batch_entropy_pool = kmalloc(2*size*sizeof(__u32), GFP_KERNEL);
if (!batch_entropy_pool)
return -1;
batch_entropy_credit =kmalloc(size*sizeof(int), GFP_KERNEL);
if (!batch_entropy_credit) {
kfree(batch_entropy_pool);
return -1;
}
batch_head = batch_tail = 0;
batch_max = size;
batch_tqueue.routine = batch_entropy_process;
batch_tqueue.data = r;
return 0;
}
void batch_entropy_store(u32 a, u32 b, int num)
{
int new;
if (!batch_max)
return;
batch_entropy_pool[2*batch_head] = a;
batch_entropy_pool[(2*batch_head) + 1] = b;
batch_entropy_credit[batch_head] = num;
new = (batch_head+1) & (batch_max-1);
if (new != batch_tail) {
queue_task(&batch_tqueue, &tq_timer);
batch_head = new;
} else {
#if 0
printk(KERN_NOTICE "random: batch entropy buffer full\n");
#endif
}
}
static void batch_entropy_process(void *private_)
{
int num = 0;
int max_entropy;
struct entropy_store *r = (struct entropy_store *) private_, *p;
if (!batch_max)
return;
max_entropy = r->poolinfo.poolwords*32;
while (batch_head != batch_tail) {
add_entropy_words(r, batch_entropy_pool + 2*batch_tail, 2);
p = r;
if (r->entropy_count > max_entropy && (num & 1))
r = sec_random_state;
credit_entropy_store(r, batch_entropy_credit[batch_tail]);
batch_tail = (batch_tail+1) & (batch_max-1);
num++;
}
if (r->entropy_count >= random_read_wakeup_thresh)
wake_up_interruptible(&random_read_wait);
}
/*********************************************************************
*
* Entropy input management
*
*********************************************************************/
/* There is one of these per entropy source */
struct timer_rand_state {
__u32 last_time;
__s32 last_delta,last_delta2;
int dont_count_entropy:1;
};
static struct timer_rand_state keyboard_timer_state;
static struct timer_rand_state mouse_timer_state;
static struct timer_rand_state extract_timer_state;
static struct timer_rand_state *irq_timer_state[NR_IRQS];
static struct timer_rand_state *blkdev_timer_state[MAX_BLKDEV];
/*
* This function adds entropy to the entropy "pool" by using timing
* delays. It uses the timer_rand_state structure to make an estimate
* of how many bits of entropy this call has added to the pool.
*
* The number "num" is also added to the pool - it should somehow describe
* the type of event which just happened. This is currently 0-255 for
* keyboard scan codes, and 256 upwards for interrupts.
* On the i386, this is assumed to be at most 16 bits, and the high bits
* are used for a high-resolution timer.
*
*/
static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
{
__u32 time;
__s32 delta, delta2, delta3;
int entropy = 0;
#if defined (__i386__)
if ( test_bit(X86_FEATURE_TSC, &boot_cpu_data.x86_capability) ) {
__u32 high;
__asm__(".byte 0x0f,0x31"
:"=a" (time), "=d" (high));
num ^= high;
} else {
time = jiffies;
}
#else
time = jiffies;
#endif
/*
* Calculate number of bits of randomness we probably added.
* We take into account the first, second and third-order deltas
* in order to make our estimate.
*/
if (!state->dont_count_entropy) {
delta = time - state->last_time;
state->last_time = time;
delta2 = delta - state->last_delta;
state->last_delta = delta;
delta3 = delta2 - state->last_delta2;
state->last_delta2 = delta2;
if (delta < 0)
delta = -delta;
if (delta2 < 0)
delta2 = -delta2;
if (delta3 < 0)
delta3 = -delta3;
if (delta > delta2)
delta = delta2;
if (delta > delta3)
delta = delta3;
/*
* delta is now minimum absolute delta.
* Round down by 1 bit on general principles,
* and limit entropy entimate to 12 bits.
*/
delta >>= 1;
delta &= (1 << 12) - 1;
entropy = int_ln_12bits(delta);
}
batch_entropy_store(num, time, entropy);
}
void add_keyboard_randomness(unsigned char scancode)
{
static unsigned char last_scancode;
/* ignore autorepeat (multiple key down w/o key up) */
if (scancode != last_scancode) {
last_scancode = scancode;
add_timer_randomness(&keyboard_timer_state, scancode);
}
}
void add_mouse_randomness(__u32 mouse_data)
{
add_timer_randomness(&mouse_timer_state, mouse_data);
}
void add_interrupt_randomness(int irq)
{
if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
return;
add_timer_randomness(irq_timer_state[irq], 0x100+irq);
}
void add_blkdev_randomness(int major)
{
if (major >= MAX_BLKDEV)
return;
if (blkdev_timer_state[major] == 0) {
rand_initialize_blkdev(major, GFP_ATOMIC);
if (blkdev_timer_state[major] == 0)
return;
}
add_timer_randomness(blkdev_timer_state[major], 0x200+major);
}
/******************************************************************
*
* Hash function definition
*
*******************************************************************/
/*
* This chunk of code defines a function
* void HASH_TRANSFORM(__u32 digest[HASH_BUFFER_SIZE + HASH_EXTRA_SIZE],
* __u32 const data[16])
*
* The function hashes the input data to produce a digest in the first
* HASH_BUFFER_SIZE words of the digest[] array, and uses HASH_EXTRA_SIZE
* more words for internal purposes. (This buffer is exported so the
* caller can wipe it once rather than this code doing it each call,
* and tacking it onto the end of the digest[] array is the quick and
* dirty way of doing it.)
*
* It so happens that MD5 and SHA share most of the initial vector
* used to initialize the digest[] array before the first call:
* 1) 0x67452301
* 2) 0xefcdab89
* 3) 0x98badcfe
* 4) 0x10325476
* 5) 0xc3d2e1f0 (SHA only)
*
* For /dev/random purposes, the length of the data being hashed is
* fixed in length, so appending a bit count in the usual way is not
* cryptographically necessary.
*/
#ifdef USE_SHA
#define HASH_BUFFER_SIZE 5
#define HASH_EXTRA_SIZE 80
#define HASH_TRANSFORM SHATransform
/* Various size/speed tradeoffs are available. Choose 0..3. */
#define SHA_CODE_SIZE 0
/*
* SHA transform algorithm, taken from code written by Peter Gutmann,
* and placed in the public domain.
*/
/* The SHA f()-functions. */
#define f1(x,y,z) ( z ^ (x & (y^z)) ) /* Rounds 0-19: x ? y : z */
#define f2(x,y,z) (x ^ y ^ z) /* Rounds 20-39: XOR */
#define f3(x,y,z) ( (x & y) + (z & (x ^ y)) ) /* Rounds 40-59: majority */
#define f4(x,y,z) (x ^ y ^ z) /* Rounds 60-79: XOR */
/* The SHA Mysterious Constants */
#define K1 0x5A827999L /* Rounds 0-19: sqrt(2) * 2^30 */
#define K2 0x6ED9EBA1L /* Rounds 20-39: sqrt(3) * 2^30 */
#define K3 0x8F1BBCDCL /* Rounds 40-59: sqrt(5) * 2^30 */
#define K4 0xCA62C1D6L /* Rounds 60-79: sqrt(10) * 2^30 */
#define ROTL(n,X) ( ( ( X ) << n ) | ( ( X ) >> ( 32 - n ) ) )
#define subRound(a, b, c, d, e, f, k, data) \
( e += ROTL( 5, a ) + f( b, c, d ) + k + data, b = ROTL( 30, b ) )
static void SHATransform(__u32 digest[85], __u32 const data[16])
{
__u32 A, B, C, D, E; /* Local vars */
__u32 TEMP;
int i;
#define W (digest + HASH_BUFFER_SIZE) /* Expanded data array */
/*
* Do the preliminary expansion of 16 to 80 words. Doing it
* out-of-line line this is faster than doing it in-line on
* register-starved machines like the x86, and not really any
* slower on real processors.
*/
memcpy(W, data, 16*sizeof(__u32));
for (i = 0; i < 64; i++) {
TEMP = W[i] ^ W[i+2] ^ W[i+8] ^ W[i+13];
W[i+16] = ROTL(1, TEMP);
}
/* Set up first buffer and local data buffer */
A = digest[ 0 ];
B = digest[ 1 ];
C = digest[ 2 ];
D = digest[ 3 ];
E = digest[ 4 ];
/* Heavy mangling, in 4 sub-rounds of 20 iterations each. */
#if SHA_CODE_SIZE == 0
/*
* Approximately 50% of the speed of the largest version, but
* takes up 1/16 the space. Saves about 6k on an i386 kernel.
*/
for (i = 0; i < 80; i++) {
if (i < 40) {
if (i < 20)
TEMP = f1(B, C, D) + K1;
else
TEMP = f2(B, C, D) + K2;
} else {
if (i < 60)
TEMP = f3(B, C, D) + K3;
else
TEMP = f4(B, C, D) + K4;
}
TEMP += ROTL(5, A) + E + W[i];
E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
}
#elif SHA_CODE_SIZE == 1
for (i = 0; i < 20; i++) {
TEMP = f1(B, C, D) + K1 + ROTL(5, A) + E + W[i];
E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
}
for (; i < 40; i++) {
TEMP = f2(B, C, D) + K2 + ROTL(5, A) + E + W[i];
E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
}
for (; i < 60; i++) {
TEMP = f3(B, C, D) + K3 + ROTL(5, A) + E + W[i];
E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
}
for (; i < 80; i++) {
TEMP = f4(B, C, D) + K4 + ROTL(5, A) + E + W[i];
E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;
}
#elif SHA_CODE_SIZE == 2
for (i = 0; i < 20; i += 5) {
subRound( A, B, C, D, E, f1, K1, W[ i ] );
subRound( E, A, B, C, D, f1, K1, W[ i+1 ] );
subRound( D, E, A, B, C, f1, K1, W[ i+2 ] );
subRound( C, D, E, A, B, f1, K1, W[ i+3 ] );
subRound( B, C, D, E, A, f1, K1, W[ i+4 ] );
}
for (; i < 40; i += 5) {
subRound( A, B, C, D, E, f2, K2, W[ i ] );
subRound( E, A, B, C, D, f2, K2, W[ i+1 ] );
subRound( D, E, A, B, C, f2, K2, W[ i+2 ] );
subRound( C, D, E, A, B, f2, K2, W[ i+3 ] );
subRound( B, C, D, E, A, f2, K2, W[ i+4 ] );
}
for (; i < 60; i += 5) {
subRound( A, B, C, D, E, f3, K3, W[ i ] );
subRound( E, A, B, C, D, f3, K3, W[ i+1 ] );
subRound( D, E, A, B, C, f3, K3, W[ i+2 ] );
subRound( C, D, E, A, B, f3, K3, W[ i+3 ] );
subRound( B, C, D, E, A, f3, K3, W[ i+4 ] );
}
for (; i < 80; i += 5) {
subRound( A, B, C, D, E, f4, K4, W[ i ] );
subRound( E, A, B, C, D, f4, K4, W[ i+1 ] );
subRound( D, E, A, B, C, f4, K4, W[ i+2 ] );
subRound( C, D, E, A, B, f4, K4, W[ i+3 ] );
subRound( B, C, D, E, A, f4, K4, W[ i+4 ] );
}
#elif SHA_CODE_SIZE == 3 /* Really large version */
subRound( A, B, C, D, E, f1, K1, W[ 0 ] );
subRound( E, A, B, C, D, f1, K1, W[ 1 ] );
subRound( D, E, A, B, C, f1, K1, W[ 2 ] );
subRound( C, D, E, A, B, f1, K1, W[ 3 ] );
subRound( B, C, D, E, A, f1, K1, W[ 4 ] );
subRound( A, B, C, D, E, f1, K1, W[ 5 ] );
subRound( E, A, B, C, D, f1, K1, W[ 6 ] );
subRound( D, E, A, B, C, f1, K1, W[ 7 ] );
subRound( C, D, E, A, B, f1, K1, W[ 8 ] );
subRound( B, C, D, E, A, f1, K1, W[ 9 ] );
subRound( A, B, C, D, E, f1, K1, W[ 10 ] );
subRound( E, A, B, C, D, f1, K1, W[ 11 ] );
subRound( D, E, A, B, C, f1, K1, W[ 12 ] );
subRound( C, D, E, A, B, f1, K1, W[ 13 ] );
subRound( B, C, D, E, A, f1, K1, W[ 14 ] );
subRound( A, B, C, D, E, f1, K1, W[ 15 ] );
subRound( E, A, B, C, D, f1, K1, W[ 16 ] );
subRound( D, E, A, B, C, f1, K1, W[ 17 ] );
subRound( C, D, E, A, B, f1, K1, W[ 18 ] );
subRound( B, C, D, E, A, f1, K1, W[ 19 ] );
subRound( A, B, C, D, E, f2, K2, W[ 20 ] );
subRound( E, A, B, C, D, f2, K2, W[ 21 ] );
subRound( D, E, A, B, C, f2, K2, W[ 22 ] );
subRound( C, D, E, A, B, f2, K2, W[ 23 ] );
subRound( B, C, D, E, A, f2, K2, W[ 24 ] );
subRound( A, B, C, D, E, f2, K2, W[ 25 ] );
subRound( E, A, B, C, D, f2, K2, W[ 26 ] );
subRound( D, E, A, B, C, f2, K2, W[ 27 ] );
subRound( C, D, E, A, B, f2, K2, W[ 28 ] );
subRound( B, C, D, E, A, f2, K2, W[ 29 ] );
subRound( A, B, C, D, E, f2, K2, W[ 30 ] );
subRound( E, A, B, C, D, f2, K2, W[ 31 ] );
subRound( D, E, A, B, C, f2, K2, W[ 32 ] );
subRound( C, D, E, A, B, f2, K2, W[ 33 ] );
subRound( B, C, D, E, A, f2, K2, W[ 34 ] );
subRound( A, B, C, D, E, f2, K2, W[ 35 ] );
subRound( E, A, B, C, D, f2, K2, W[ 36 ] );
subRound( D, E, A, B, C, f2, K2, W[ 37 ] );
subRound( C, D, E, A, B, f2, K2, W[ 38 ] );
subRound( B, C, D, E, A, f2, K2, W[ 39 ] );
subRound( A, B, C, D, E, f3, K3, W[ 40 ] );
subRound( E, A, B, C, D, f3, K3, W[ 41 ] );
subRound( D, E, A, B, C, f3, K3, W[ 42 ] );
subRound( C, D, E, A, B, f3, K3, W[ 43 ] );
subRound( B, C, D, E, A, f3, K3, W[ 44 ] );
subRound( A, B, C, D, E, f3, K3, W[ 45 ] );
subRound( E, A, B, C, D, f3, K3, W[ 46 ] );
subRound( D, E, A, B, C, f3, K3, W[ 47 ] );
subRound( C, D, E, A, B, f3, K3, W[ 48 ] );
subRound( B, C, D, E, A, f3, K3, W[ 49 ] );
subRound( A, B, C, D, E, f3, K3, W[ 50 ] );
subRound( E, A, B, C, D, f3, K3, W[ 51 ] );
subRound( D, E, A, B, C, f3, K3, W[ 52 ] );
subRound( C, D, E, A, B, f3, K3, W[ 53 ] );
subRound( B, C, D, E, A, f3, K3, W[ 54 ] );
subRound( A, B, C, D, E, f3, K3, W[ 55 ] );
subRound( E, A, B, C, D, f3, K3, W[ 56 ] );
subRound( D, E, A, B, C, f3, K3, W[ 57 ] );
subRound( C, D, E, A, B, f3, K3, W[ 58 ] );
subRound( B, C, D, E, A, f3, K3, W[ 59 ] );
subRound( A, B, C, D, E, f4, K4, W[ 60 ] );
subRound( E, A, B, C, D, f4, K4, W[ 61 ] );
subRound( D, E, A, B, C, f4, K4, W[ 62 ] );
subRound( C, D, E, A, B, f4, K4, W[ 63 ] );
subRound( B, C, D, E, A, f4, K4, W[ 64 ] );
subRound( A, B, C, D, E, f4, K4, W[ 65 ] );
subRound( E, A, B, C, D, f4, K4, W[ 66 ] );
subRound( D, E, A, B, C, f4, K4, W[ 67 ] );
subRound( C, D, E, A, B, f4, K4, W[ 68 ] );
subRound( B, C, D, E, A, f4, K4, W[ 69 ] );
subRound( A, B, C, D, E, f4, K4, W[ 70 ] );
subRound( E, A, B, C, D, f4, K4, W[ 71 ] );
subRound( D, E, A, B, C, f4, K4, W[ 72 ] );
subRound( C, D, E, A, B, f4, K4, W[ 73 ] );
subRound( B, C, D, E, A, f4, K4, W[ 74 ] );
subRound( A, B, C, D, E, f4, K4, W[ 75 ] );
subRound( E, A, B, C, D, f4, K4, W[ 76 ] );
subRound( D, E, A, B, C, f4, K4, W[ 77 ] );
subRound( C, D, E, A, B, f4, K4, W[ 78 ] );
subRound( B, C, D, E, A, f4, K4, W[ 79 ] );
#else
#error Illegal SHA_CODE_SIZE
#endif
/* Build message digest */
digest[ 0 ] += A;
digest[ 1 ] += B;
digest[ 2 ] += C;
digest[ 3 ] += D;
digest[ 4 ] += E;
/* W is wiped by the caller */
#undef W
}
#undef ROTL
#undef f1
#undef f2
#undef f3
#undef f4
#undef K1
#undef K2
#undef K3
#undef K4
#undef subRound
#else /* !USE_SHA - Use MD5 */
#define HASH_BUFFER_SIZE 4
#define HASH_EXTRA_SIZE 0
#define HASH_TRANSFORM MD5Transform
/*
* MD5 transform algorithm, taken from code written by Colin Plumb,
* and put into the public domain
*/
/* The four core functions - F1 is optimized somewhat */
/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))
/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
/*
* The core of the MD5 algorithm, this alters an existing MD5 hash to
* reflect the addition of 16 longwords of new data. MD5Update blocks
* the data and converts bytes into longwords for this routine.
*/
static void MD5Transform(__u32 buf[HASH_BUFFER_SIZE], __u32 const in[16])
{
__u32 a, b, c, d;
a = buf[0];
b = buf[1];
c = buf[2];
d = buf[3];
MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7);
MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7);
MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7);
MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7);
MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5);
MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9);
MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5);
MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9);
MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5);
MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9);
MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5);
MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9);
MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4);
MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4);
MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4);
MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4);
MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6);
MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6);
MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6);
MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6);
MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
#undef F1
#undef F2
#undef F3
#undef F4
#undef MD5STEP
#endif /* !USE_SHA */
/*********************************************************************
*
* Entropy extraction routines
*
*********************************************************************/
#define EXTRACT_ENTROPY_USER 1
#define EXTRACT_ENTROPY_SECONDARY 2
#define TMP_BUF_SIZE (HASH_BUFFER_SIZE + HASH_EXTRA_SIZE)
#define SEC_XFER_SIZE (TMP_BUF_SIZE*4)
static ssize_t extract_entropy(struct entropy_store *r, void * buf,
size_t nbytes, int flags);
/*
* This utility inline function is responsible for transfering entropy
* from the primary pool to the secondary extraction pool. We pull
* randomness under two conditions; one is if there isn't enough entropy
* in the secondary pool. The other is after we have extract 1024 bytes,
* at which point we do a "catastrophic reseeding".
*/
static inline void xfer_secondary_pool(struct entropy_store *r,
size_t nbytes)
{
__u32 tmp[TMP_BUF_SIZE];
if (r->entropy_count < nbytes*8) {
extract_entropy(random_state, tmp, sizeof(tmp), 0);
add_entropy_words(r, tmp, TMP_BUF_SIZE);
credit_entropy_store(r, TMP_BUF_SIZE*8);
}
if (r->extract_count > 1024) {
extract_entropy(random_state, tmp, sizeof(tmp), 0);
add_entropy_words(r, tmp, TMP_BUF_SIZE);
r->extract_count = 0;
}
}
/*
* This function extracts randomness from the "entropy pool", and
* returns it in a buffer. This function computes how many remaining
* bits of entropy are left in the pool, but it does not restrict the
* number of bytes that are actually obtained. If the EXTRACT_ENTROPY_USER
* flag is given, then the buf pointer is assumed to be in user space.
* If the EXTRACT_ENTROPY_SECONDARY flag is given, then this function will
*
* Note: extract_entropy() assumes that POOLWORDS is a multiple of 16 words.
*/
static ssize_t extract_entropy(struct entropy_store *r, void * buf,
size_t nbytes, int flags)
{
ssize_t ret, i;
__u32 tmp[TMP_BUF_SIZE];
__u32 x;
add_timer_randomness(&extract_timer_state, nbytes);
/* Redundant, but just in case... */
if (r->entropy_count > r->poolinfo.poolwords)
r->entropy_count = r->poolinfo.poolwords;
if (flags & EXTRACT_ENTROPY_SECONDARY)
xfer_secondary_pool(r, nbytes);
if (r->entropy_count / 8 >= nbytes)
r->entropy_count -= nbytes*8;
else
r->entropy_count = 0;
if (r->entropy_count < random_write_wakeup_thresh)
wake_up_interruptible(&random_write_wait);
r->extract_count += nbytes;
ret = 0;
while (nbytes) {
/*
* Check if we need to break out or reschedule....
*/
if ((flags & EXTRACT_ENTROPY_USER) && current->need_resched) {
if (signal_pending(current)) {
if (ret == 0)
ret = -ERESTARTSYS;
break;
}
schedule();
}
/* Hash the pool to get the output */
tmp[0] = 0x67452301;
tmp[1] = 0xefcdab89;
tmp[2] = 0x98badcfe;
tmp[3] = 0x10325476;
#ifdef USE_SHA
tmp[4] = 0xc3d2e1f0;
#endif
/*
* As we hash the pool, we mix intermediate values of
* the hash back into the pool. This eliminates
* backtracking attacks (where the attacker knows
* the state of the pool plus the current outputs, and
* attempts to find previous ouputs), unless the hash
* function can be inverted.
*/
for (i = 0, x = 0; i < r->poolinfo.poolwords; i += 16, x+=2) {
HASH_TRANSFORM(tmp, r->pool+i);
add_entropy_words(r, &tmp[x%HASH_BUFFER_SIZE], 1);
}
/*
* In case the hash function has some recognizable
* output pattern, we fold it in half.
*/
for (i = 0; i < HASH_BUFFER_SIZE/2; i++)
tmp[i] ^= tmp[i + (HASH_BUFFER_SIZE+1)/2];
#if HASH_BUFFER_SIZE & 1 /* There's a middle word to deal with */
x = tmp[HASH_BUFFER_SIZE/2];
x ^= (x >> 16); /* Fold it in half */
((__u16 *)tmp)[HASH_BUFFER_SIZE-1] = (__u16)x;
#endif
/* Copy data to destination buffer */
i = MIN(nbytes, HASH_BUFFER_SIZE*sizeof(__u32)/2);
if (flags & EXTRACT_ENTROPY_USER) {
i -= copy_to_user(buf, (__u8 const *)tmp, i);
if (!i) {
ret = -EFAULT;
break;
}
} else
memcpy(buf, (__u8 const *)tmp, i);
nbytes -= i;
buf += i;
ret += i;
add_timer_randomness(&extract_timer_state, nbytes);
}
/* Wipe data just returned from memory */
memset(tmp, 0, sizeof(tmp));
return ret;
}
/*
* This function is the exported kernel interface. It returns some
* number of good random numbers, suitable for seeding TCP sequence
* numbers, etc.
*/
void get_random_bytes(void *buf, int nbytes)
{
if (sec_random_state)
extract_entropy(sec_random_state, (char *) buf, nbytes,
EXTRACT_ENTROPY_SECONDARY);
else if (random_state)
extract_entropy(random_state, (char *) buf, nbytes, 0);
else
printk(KERN_NOTICE "get_random_bytes called before "
"random driver initialization\n");
}
/*********************************************************************
*
* Functions to interface with Linux
*
*********************************************************************/
/*
* Initialize the random pool with standard stuff.
*
* NOTE: This is an OS-dependent function.
*/
static void init_std_data(struct entropy_store *r)
{
struct timeval tv;
__u32 words[2];
char *p;
int i;
do_gettimeofday(&tv);
words[0] = tv.tv_sec;
words[1] = tv.tv_usec;
add_entropy_words(r, words, 2);
/*
* This doesn't lock system.utsname. However, we are generating
* entropy so a race with a name set here is fine.
*/
p = (char *) &system_utsname;
for (i = sizeof(system_utsname) / sizeof(words); i; i--) {
memcpy(words, p, sizeof(words));
add_entropy_words(r, words, sizeof(words)/4);
p += sizeof(words);
}
}
void __init rand_initialize(void)
{
int i;
if (create_entropy_store(DEFAULT_POOL_SIZE, &random_state))
return; /* Error, return */
if (batch_entropy_init(BATCH_ENTROPY_SIZE, random_state))
return; /* Error, return */
if (create_entropy_store(SECONDARY_POOL_SIZE, &sec_random_state))
return; /* Error, return */
clear_entropy_store(random_state);
clear_entropy_store(sec_random_state);
init_std_data(random_state);
#ifdef CONFIG_SYSCTL
sysctl_init_random(random_state);
#endif
for (i = 0; i < NR_IRQS; i++)
irq_timer_state[i] = NULL;
for (i = 0; i < MAX_BLKDEV; i++)
blkdev_timer_state[i] = NULL;
memset(&keyboard_timer_state, 0, sizeof(struct timer_rand_state));
memset(&mouse_timer_state, 0, sizeof(struct timer_rand_state));
memset(&extract_timer_state, 0, sizeof(struct timer_rand_state));
extract_timer_state.dont_count_entropy = 1;
}
void rand_initialize_irq(int irq)
{
struct timer_rand_state *state;
if (irq >= NR_IRQS || irq_timer_state[irq])
return;
/*
* If kmalloc returns null, we just won't use that entropy
* source.
*/
state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
if (state) {
memset(state, 0, sizeof(struct timer_rand_state));
irq_timer_state[irq] = state;
}
}
void rand_initialize_blkdev(int major, int mode)
{
struct timer_rand_state *state;
if (major >= MAX_BLKDEV || blkdev_timer_state[major])
return;
/*
* If kmalloc returns null, we just won't use that entropy
* source.
*/
state = kmalloc(sizeof(struct timer_rand_state), mode);
if (state) {
memset(state, 0, sizeof(struct timer_rand_state));
blkdev_timer_state[major] = state;
}
}
static ssize_t
random_read(struct file * file, char * buf, size_t nbytes, loff_t *ppos)
{
DECLARE_WAITQUEUE(wait, current);
ssize_t n, retval = 0, count = 0;
if (nbytes == 0)
return 0;
add_wait_queue(&random_read_wait, &wait);
while (nbytes > 0) {
set_current_state(TASK_INTERRUPTIBLE);
n = nbytes;
if (n > SEC_XFER_SIZE)
n = SEC_XFER_SIZE;
if (n > random_state->entropy_count / 8)
n = random_state->entropy_count / 8;
if (n == 0) {
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
schedule();
continue;
}
n = extract_entropy(sec_random_state, buf, n,
EXTRACT_ENTROPY_USER |
EXTRACT_ENTROPY_SECONDARY);
if (n < 0) {
retval = n;
break;
}
count += n;
buf += n;
nbytes -= n;
break; /* This break makes the device work */
/* like a named pipe */
}
current->state = TASK_RUNNING;
remove_wait_queue(&random_read_wait, &wait);
/*
* If we gave the user some bytes, update the access time.
*/
if (count != 0) {
UPDATE_ATIME(file->f_dentry->d_inode);
}
return (count ? count : retval);
}
static ssize_t
urandom_read(struct file * file, char * buf,
size_t nbytes, loff_t *ppos)
{
return extract_entropy(sec_random_state, buf, nbytes,
EXTRACT_ENTROPY_USER |
EXTRACT_ENTROPY_SECONDARY);
}
static unsigned int
random_poll(struct file *file, poll_table * wait)
{
unsigned int mask;
poll_wait(file, &random_read_wait, wait);
poll_wait(file, &random_write_wait, wait);
mask = 0;
if (random_state->entropy_count >= random_read_wakeup_thresh)
mask |= POLLIN | POLLRDNORM;
if (random_state->entropy_count < random_write_wakeup_thresh)
mask |= POLLOUT | POLLWRNORM;
return mask;
}
static ssize_t
random_write(struct file * file, const char * buffer,
size_t count, loff_t *ppos)
{
int ret = 0;
size_t bytes;
__u32 buf[16];
const char *p = buffer;
size_t c = count;
while (c > 0) {
bytes = MIN(c, sizeof(buf));
bytes -= copy_from_user(&buf, p, bytes);
if (!bytes) {
ret = -EFAULT;
break;
}
c -= bytes;
p += bytes;
/* Convert bytes to words */
bytes = (bytes + 3) / sizeof(__u32);
add_entropy_words(random_state, buf, bytes);
}
if (p == buffer) {
return (ssize_t)ret;
} else {
file->f_dentry->d_inode->i_mtime = CURRENT_TIME;
mark_inode_dirty(file->f_dentry->d_inode);
return (ssize_t)(p - buffer);
}
}
static int
random_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg)
{
int *p, size, ent_count;
int retval;
switch (cmd) {
case RNDGETENTCNT:
ent_count = random_state->entropy_count;
if (put_user(ent_count, (int *) arg))
return -EFAULT;
return 0;
case RNDADDTOENTCNT:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(ent_count, (int *) arg))
return -EFAULT;
credit_entropy_store(random_state, ent_count);
/*
* Wake up waiting processes if we have enough
* entropy.
*/
if (random_state->entropy_count >= random_read_wakeup_thresh)
wake_up_interruptible(&random_read_wait);
return 0;
case RNDGETPOOL:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
p = (int *) arg;
ent_count = random_state->entropy_count;
if (put_user(ent_count, p++))
return -EFAULT;
if (get_user(size, p))
return -EFAULT;
if (put_user(random_state->poolinfo.poolwords, p++))
return -EFAULT;
if (size < 0)
return -EINVAL;
if (size > random_state->poolinfo.poolwords)
size = random_state->poolinfo.poolwords;
if (copy_to_user(p, random_state->pool, size*sizeof(__u32)))
return -EFAULT;
return 0;
case RNDADDENTROPY:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
p = (int *) arg;
if (get_user(ent_count, p++))
return -EFAULT;
if (ent_count < 0)
return -EINVAL;
if (get_user(size, p++))
return -EFAULT;
retval = random_write(file, (const char *) p,
size, &file->f_pos);
if (retval < 0)
return retval;
credit_entropy_store(random_state, ent_count);
/*
* Wake up waiting processes if we have enough
* entropy.
*/
if (random_state->entropy_count >= random_read_wakeup_thresh)
wake_up_interruptible(&random_read_wait);
return 0;
case RNDZAPENTCNT:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
random_state->entropy_count = 0;
return 0;
case RNDCLEARPOOL:
/* Clear the entropy pool and associated counters. */
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
clear_entropy_store(random_state);
init_std_data(random_state);
return 0;
default:
return -EINVAL;
}
}
struct file_operations random_fops = {
read: random_read,
write: random_write,
poll: random_poll,
ioctl: random_ioctl,
};
struct file_operations urandom_fops = {
read: urandom_read,
write: random_write,
ioctl: random_ioctl,
};
/***************************************************************
* Random UUID interface
*
* Used here for a Boot ID, but can be useful for other kernel
* drivers.
***************************************************************/
/*
* Generate random UUID
*/
void generate_random_uuid(unsigned char uuid_out[16])
{
get_random_bytes(uuid_out, 16);
/* Set UUID version to 4 --- truely random generation */
uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
/* Set the UUID variant to DCE */
uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
}
/********************************************************************
*
* Sysctl interface
*
********************************************************************/
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
static int sysctl_poolsize;
static int min_read_thresh, max_read_thresh;
static int min_write_thresh, max_write_thresh;
static char sysctl_bootid[16];
/*
* This function handles a request from the user to change the pool size
* of the primary entropy store.
*/
static int change_poolsize(int poolsize)
{
struct entropy_store *new_store, *old_store;
int ret;
if ((ret = create_entropy_store(poolsize, &new_store)))
return ret;
add_entropy_words(new_store, random_state->pool,
random_state->poolinfo.poolwords);
credit_entropy_store(new_store, random_state->entropy_count);
sysctl_init_random(new_store);
old_store = random_state;
random_state = batch_tqueue.data = new_store;
free_entropy_store(old_store);
return 0;
}
static int proc_do_poolsize(ctl_table *table, int write, struct file *filp,
void *buffer, size_t *lenp)
{
int ret;
sysctl_poolsize = random_state->poolinfo.poolwords * 4;
ret = proc_dointvec(table, write, filp, buffer, lenp);
if (ret || !write ||
(sysctl_poolsize == random_state->poolinfo.poolwords * 4))
return ret;
return change_poolsize(sysctl_poolsize);
}
static int poolsize_strategy(ctl_table *table, int *name, int nlen,
void *oldval, size_t *oldlenp,
void *newval, size_t newlen, void **context)
{
int len;
sysctl_poolsize = random_state->poolinfo.poolwords * 4;
/*
* We only handle the write case, since the read case gets
* handled by the default handler (and we don't care if the
* write case happens twice; it's harmless).
*/
if (newval && newlen) {
len = newlen;
if (len > table->maxlen)
len = table->maxlen;
if (copy_from_user(table->data, newval, len))
return -EFAULT;
}
if (sysctl_poolsize != random_state->poolinfo.poolwords * 4)
return change_poolsize(sysctl_poolsize);
return 0;
}
/*
* These functions is used to return both the bootid UUID, and random
* UUID. The difference is in whether table->data is NULL; if it is,
* then a new UUID is generated and returned to the user.
*
* If the user accesses this via the proc interface, it will be returned
* as an ASCII string in the standard UUID format. If accesses via the
* sysctl system call, it is returned as 16 bytes of binary data.
*/
static int proc_do_uuid(ctl_table *table, int write, struct file *filp,
void *buffer, size_t *lenp)
{
ctl_table fake_table;
unsigned char buf[64], tmp_uuid[16], *uuid;
uuid = table->data;
if (!uuid) {
uuid = tmp_uuid;
uuid[8] = 0;
}
if (uuid[8] == 0)
generate_random_uuid(uuid);
sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
"%02x%02x%02x%02x%02x%02x",
uuid[0], uuid[1], uuid[2], uuid[3],
uuid[4], uuid[5], uuid[6], uuid[7],
uuid[8], uuid[9], uuid[10], uuid[11],
uuid[12], uuid[13], uuid[14], uuid[15]);
fake_table.data = buf;
fake_table.maxlen = sizeof(buf);
return proc_dostring(&fake_table, write, filp, buffer, lenp);
}
static int uuid_strategy(ctl_table *table, int *name, int nlen,
void *oldval, size_t *oldlenp,
void *newval, size_t newlen, void **context)
{
unsigned char tmp_uuid[16], *uuid;
int len;
if (!oldval || !oldlenp)
return 1;
uuid = table->data;
if (!uuid) {
uuid = tmp_uuid;
uuid[8] = 0;
}
if (uuid[8] == 0)
generate_random_uuid(uuid);
get_user(len, oldlenp);
if (len) {
if (len > 16)
len = 16;
if (copy_to_user(oldval, table->data, len))
return -EFAULT;
if (put_user(len, oldlenp))
return -EFAULT;
}
return 1;
}
ctl_table random_table[] = {
{RANDOM_POOLSIZE, "poolsize",
&sysctl_poolsize, sizeof(int), 0644, NULL,
&proc_do_poolsize, &poolsize_strategy},
{RANDOM_ENTROPY_COUNT, "entropy_avail",
NULL, sizeof(int), 0444, NULL,
&proc_dointvec},
{RANDOM_READ_THRESH, "read_wakeup_threshold",
&random_read_wakeup_thresh, sizeof(int), 0644, NULL,
&proc_dointvec_minmax, &sysctl_intvec, 0,
&min_read_thresh, &max_read_thresh},
{RANDOM_WRITE_THRESH, "write_wakeup_threshold",
&random_write_wakeup_thresh, sizeof(int), 0644, NULL,
&proc_dointvec_minmax, &sysctl_intvec, 0,
&min_write_thresh, &max_write_thresh},
{RANDOM_BOOT_ID, "boot_id",
&sysctl_bootid, 16, 0444, NULL,
&proc_do_uuid, &uuid_strategy},
{RANDOM_UUID, "uuid",
NULL, 16, 0444, NULL,
&proc_do_uuid, &uuid_strategy},
{0}
};
static void sysctl_init_random(struct entropy_store *random_state)
{
min_read_thresh = 8;
min_write_thresh = 0;
max_read_thresh = max_write_thresh =
random_state->poolinfo.poolwords * 32;
random_table[1].data = &random_state->entropy_count;
}
#endif /* CONFIG_SYSCTL */
/********************************************************************
*
* Random funtions for networking
*
********************************************************************/
/*
* TCP initial sequence number picking. This uses the random number
* generator to pick an initial secret value. This value is hashed
* along with the TCP endpoint information to provide a unique
* starting point for each pair of TCP endpoints. This defeats
* attacks which rely on guessing the initial TCP sequence number.
* This algorithm was suggested by Steve Bellovin.
*
* Using a very strong hash was taking an appreciable amount of the total
* TCP connection establishment time, so this is a weaker hash,
* compensated for by changing the secret periodically.
*/
/* F, G and H are basic MD4 functions: selection, majority, parity */
#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
/*
* The generic round function. The application is so specific that
* we don't bother protecting all the arguments with parens, as is generally
* good macro practice, in favor of extra legibility.
* Rotation is separate from addition to prevent recomputation
*/
#define ROUND(f, a, b, c, d, x, s) \
(a += f(b, c, d) + x, a = (a << s) | (a >> (32-s)))
#define K1 0
#define K2 013240474631UL
#define K3 015666365641UL
/*
* Basic cut-down MD4 transform. Returns only 32 bits of result.
*/
static __u32 halfMD4Transform (__u32 const buf[4], __u32 const in[8])
{
__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
/* Round 1 */
ROUND(F, a, b, c, d, in[0] + K1, 3);
ROUND(F, d, a, b, c, in[1] + K1, 7);
ROUND(F, c, d, a, b, in[2] + K1, 11);
ROUND(F, b, c, d, a, in[3] + K1, 19);
ROUND(F, a, b, c, d, in[4] + K1, 3);
ROUND(F, d, a, b, c, in[5] + K1, 7);
ROUND(F, c, d, a, b, in[6] + K1, 11);
ROUND(F, b, c, d, a, in[7] + K1, 19);
/* Round 2 */
ROUND(G, a, b, c, d, in[1] + K2, 3);
ROUND(G, d, a, b, c, in[3] + K2, 5);
ROUND(G, c, d, a, b, in[5] + K2, 9);
ROUND(G, b, c, d, a, in[7] + K2, 13);
ROUND(G, a, b, c, d, in[0] + K2, 3);
ROUND(G, d, a, b, c, in[2] + K2, 5);
ROUND(G, c, d, a, b, in[4] + K2, 9);
ROUND(G, b, c, d, a, in[6] + K2, 13);
/* Round 3 */
ROUND(H, a, b, c, d, in[3] + K3, 3);
ROUND(H, d, a, b, c, in[7] + K3, 9);
ROUND(H, c, d, a, b, in[2] + K3, 11);
ROUND(H, b, c, d, a, in[6] + K3, 15);
ROUND(H, a, b, c, d, in[1] + K3, 3);
ROUND(H, d, a, b, c, in[5] + K3, 9);
ROUND(H, c, d, a, b, in[0] + K3, 11);
ROUND(H, b, c, d, a, in[4] + K3, 15);
return buf[1] + b; /* "most hashed" word */
/* Alternative: return sum of all words? */
}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
static __u32 twothirdsMD4Transform (__u32 const buf[4], __u32 const in[12])
{
__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
/* Round 1 */
ROUND(F, a, b, c, d, in[ 0] + K1, 3);
ROUND(F, d, a, b, c, in[ 1] + K1, 7);
ROUND(F, c, d, a, b, in[ 2] + K1, 11);
ROUND(F, b, c, d, a, in[ 3] + K1, 19);
ROUND(F, a, b, c, d, in[ 4] + K1, 3);
ROUND(F, d, a, b, c, in[ 5] + K1, 7);
ROUND(F, c, d, a, b, in[ 6] + K1, 11);
ROUND(F, b, c, d, a, in[ 7] + K1, 19);
ROUND(F, a, b, c, d, in[ 8] + K1, 3);
ROUND(F, d, a, b, c, in[ 9] + K1, 7);
ROUND(F, c, d, a, b, in[10] + K1, 11);
ROUND(F, b, c, d, a, in[11] + K1, 19);
/* Round 2 */
ROUND(G, a, b, c, d, in[ 1] + K2, 3);
ROUND(G, d, a, b, c, in[ 3] + K2, 5);
ROUND(G, c, d, a, b, in[ 5] + K2, 9);
ROUND(G, b, c, d, a, in[ 7] + K2, 13);
ROUND(G, a, b, c, d, in[ 9] + K2, 3);
ROUND(G, d, a, b, c, in[11] + K2, 5);
ROUND(G, c, d, a, b, in[ 0] + K2, 9);
ROUND(G, b, c, d, a, in[ 2] + K2, 13);
ROUND(G, a, b, c, d, in[ 4] + K2, 3);
ROUND(G, d, a, b, c, in[ 6] + K2, 5);
ROUND(G, c, d, a, b, in[ 8] + K2, 9);
ROUND(G, b, c, d, a, in[10] + K2, 13);
/* Round 3 */
ROUND(H, a, b, c, d, in[ 3] + K3, 3);
ROUND(H, d, a, b, c, in[ 7] + K3, 9);
ROUND(H, c, d, a, b, in[11] + K3, 11);
ROUND(H, b, c, d, a, in[ 2] + K3, 15);
ROUND(H, a, b, c, d, in[ 6] + K3, 3);
ROUND(H, d, a, b, c, in[10] + K3, 9);
ROUND(H, c, d, a, b, in[ 1] + K3, 11);
ROUND(H, b, c, d, a, in[ 5] + K3, 15);
ROUND(H, a, b, c, d, in[ 9] + K3, 3);
ROUND(H, d, a, b, c, in[ 0] + K3, 9);
ROUND(H, c, d, a, b, in[ 4] + K3, 11);
ROUND(H, b, c, d, a, in[ 8] + K3, 15);
return buf[1] + b; /* "most hashed" word */
/* Alternative: return sum of all words? */
}
#endif
#undef ROUND
#undef F
#undef G
#undef H
#undef K1
#undef K2
#undef K3
/* This should not be decreased so low that ISNs wrap too fast. */
#define REKEY_INTERVAL 300
#define HASH_BITS 24
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
__u32 secure_tcpv6_sequence_number(__u32 *saddr, __u32 *daddr,
__u16 sport, __u16 dport)
{
static __u32 rekey_time;
static __u32 count;
static __u32 secret[12];
struct timeval tv;
__u32 seq;
/* The procedure is the same as for IPv4, but addresses are longer. */
do_gettimeofday(&tv); /* We need the usecs below... */
if (!rekey_time || (tv.tv_sec - rekey_time) > REKEY_INTERVAL) {
rekey_time = tv.tv_sec;
/* First five words are overwritten below. */
get_random_bytes(&secret[5], sizeof(secret)-5*4);
count = (tv.tv_sec/REKEY_INTERVAL) << HASH_BITS;
}
memcpy(secret, saddr, 16);
secret[4]=(sport << 16) + dport;
seq = (twothirdsMD4Transform(daddr, secret) &
((1<<HASH_BITS)-1)) + count;
seq += tv.tv_usec + tv.tv_sec*1000000;
return seq;
}
__u32 secure_ipv6_id(__u32 *daddr)
{
static time_t rekey_time;
static __u32 secret[12];
time_t t;
/*
* Pick a random secret every REKEY_INTERVAL seconds.
*/
t = CURRENT_TIME;
if (!rekey_time || (t - rekey_time) > REKEY_INTERVAL) {
rekey_time = t;
/* First word is overwritten below. */
get_random_bytes(secret, sizeof(secret));
}
return twothirdsMD4Transform(daddr, secret);
}
#endif
__u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr,
__u16 sport, __u16 dport)
{
static __u32 rekey_time;
static __u32 count;
static __u32 secret[12];
struct timeval tv;
__u32 seq;
/*
* Pick a random secret every REKEY_INTERVAL seconds.
*/
do_gettimeofday(&tv); /* We need the usecs below... */
if (!rekey_time || (tv.tv_sec - rekey_time) > REKEY_INTERVAL) {
rekey_time = tv.tv_sec;
/* First three words are overwritten below. */
get_random_bytes(&secret[3], sizeof(secret)-12);
count = (tv.tv_sec/REKEY_INTERVAL) << HASH_BITS;
}
/*
* Pick a unique starting offset for each TCP connection endpoints
* (saddr, daddr, sport, dport).
* Note that the words are placed into the first words to be
* mixed in with the halfMD4. This is because the starting
* vector is also a random secret (at secret+8), and further
* hashing fixed data into it isn't going to improve anything,
* so we should get started with the variable data.
*/
secret[0]=saddr;
secret[1]=daddr;
secret[2]=(sport << 16) + dport;
seq = (halfMD4Transform(secret+8, secret) &
((1<<HASH_BITS)-1)) + count;
/*
* As close as possible to RFC 793, which
* suggests using a 250 kHz clock.
* Further reading shows this assumes 2 Mb/s networks.
* For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
* That's funny, Linux has one built in! Use it!
* (Networks are faster now - should this be increased?)
*/
seq += tv.tv_usec + tv.tv_sec*1000000;
#if 0
printk("init_seq(%lx, %lx, %d, %d) = %d\n",
saddr, daddr, sport, dport, seq);
#endif
return seq;
}
/* The code below is shamelessly stolen from secure_tcp_sequence_number().
* All blames to Andrey V. Savochkin <saw@msu.ru>.
*/
__u32 secure_ip_id(__u32 daddr)
{
static time_t rekey_time;
static __u32 secret[12];
time_t t;
/*
* Pick a random secret every REKEY_INTERVAL seconds.
*/
t = CURRENT_TIME;
if (!rekey_time || (t - rekey_time) > REKEY_INTERVAL) {
rekey_time = t;
/* First word is overwritten below. */
get_random_bytes(secret+1, sizeof(secret)-4);
}
/*
* Pick a unique starting offset for each IP destination.
* Note that the words are placed into the first words to be
* mixed in with the halfMD4. This is because the starting
* vector is also a random secret (at secret+8), and further
* hashing fixed data into it isn't going to improve anything,
* so we should get started with the variable data.
*/
secret[0]=daddr;
return halfMD4Transform(secret+8, secret);
}
#ifdef CONFIG_SYN_COOKIES
/*
* Secure SYN cookie computation. This is the algorithm worked out by
* Dan Bernstein and Eric Schenk.
*
* For linux I implement the 1 minute counter by looking at the jiffies clock.
* The count is passed in as a parameter, so this code doesn't much care.
*/
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
static int syncookie_init;
static __u32 syncookie_secret[2][16-3+HASH_BUFFER_SIZE];
__u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr, __u16 sport,
__u16 dport, __u32 sseq, __u32 count, __u32 data)
{
__u32 tmp[16 + HASH_BUFFER_SIZE + HASH_EXTRA_SIZE];
__u32 seq;
/*
* Pick two random secrets the first time we need a cookie.
*/
if (syncookie_init == 0) {
get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
syncookie_init = 1;
}
/*
* Compute the secure sequence number.
* The output should be:
* HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
* + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
* Where sseq is their sequence number and count increases every
* minute by 1.
* As an extra hack, we add a small "data" value that encodes the
* MSS into the second hash value.
*/
memcpy(tmp+3, syncookie_secret[0], sizeof(syncookie_secret[0]));
tmp[0]=saddr;
tmp[1]=daddr;
tmp[2]=(sport << 16) + dport;
HASH_TRANSFORM(tmp+16, tmp);
seq = tmp[17] + sseq + (count << COOKIEBITS);
memcpy(tmp+3, syncookie_secret[1], sizeof(syncookie_secret[1]));
tmp[0]=saddr;
tmp[1]=daddr;
tmp[2]=(sport << 16) + dport;
tmp[3] = count; /* minute counter */
HASH_TRANSFORM(tmp+16, tmp);
/* Add in the second hash and the data */
return seq + ((tmp[17] + data) & COOKIEMASK);
}
/*
* This retrieves the small "data" value from the syncookie.
* If the syncookie is bad, the data returned will be out of
* range. This must be checked by the caller.
*
* The count value used to generate the cookie must be within
* "maxdiff" if the current (passed-in) "count". The return value
* is (__u32)-1 if this test fails.
*/
__u32 check_tcp_syn_cookie(__u32 cookie, __u32 saddr, __u32 daddr, __u16 sport,
__u16 dport, __u32 sseq, __u32 count, __u32 maxdiff)
{
__u32 tmp[16 + HASH_BUFFER_SIZE + HASH_EXTRA_SIZE];
__u32 diff;
if (syncookie_init == 0)
return (__u32)-1; /* Well, duh! */
/* Strip away the layers from the cookie */
memcpy(tmp+3, syncookie_secret[0], sizeof(syncookie_secret[0]));
tmp[0]=saddr;
tmp[1]=daddr;
tmp[2]=(sport << 16) + dport;
HASH_TRANSFORM(tmp+16, tmp);
cookie -= tmp[17] + sseq;
/* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
diff = (count - (cookie >> COOKIEBITS)) & ((__u32)-1 >> COOKIEBITS);
if (diff >= maxdiff)
return (__u32)-1;
memcpy(tmp+3, syncookie_secret[1], sizeof(syncookie_secret[1]));
tmp[0] = saddr;
tmp[1] = daddr;
tmp[2] = (sport << 16) + dport;
tmp[3] = count - diff; /* minute counter */
HASH_TRANSFORM(tmp+16, tmp);
return (cookie - tmp[17]) & COOKIEMASK; /* Leaving the data behind */
}
#endif
EXPORT_SYMBOL(add_keyboard_randomness);
EXPORT_SYMBOL(add_mouse_randomness);
EXPORT_SYMBOL(add_interrupt_randomness);
EXPORT_SYMBOL(add_blkdev_randomness);
EXPORT_SYMBOL(batch_entropy_store);
|