Mercurial > dropbear
view dbrandom.c @ 1306:34e6127ef02e
merge fixes from PuTTY import.c
toint() from misc.c
(revids are from hggit conversion)
changeset: 4620:60a336a6c85c
user: Simon Tatham <[email protected]>
date: Thu Feb 25 20:26:33 2016 +0000
files: import.c
description:
Fix potential segfaults in reading OpenSSH's ASN.1 key format.
The length coming back from ber_read_id_len might have overflowed, so
treat it as potentially negative. Also, while I'm here, accumulate it
inside ber_read_id_len as an unsigned, so as to avoid undefined
behaviour on integer overflow, and toint() it before return.
Thanks to Hanno Böck for spotting this, with the aid of AFL.
(cherry picked from commit 5b7833cd474a24ec098654dcba8cb9509f3bf2c1)
Conflicts:
import.c
(cherry-picker's note: resolving the conflict involved removing an
entire section of the original commit which fixed ECDSA code not
present on this branch)
changeset: 4619:9c6c638d98d8
user: Simon Tatham <[email protected]>
date: Sun Jul 14 10:45:54 2013 +0000
files: import.c ssh.c sshdss.c sshpubk.c sshrsa.c
description:
Tighten up a lot of casts from unsigned to int which are read by one
of the GET_32BIT macros and then used as length fields. Missing bounds
checks against zero have been added, and also I've introduced a helper
function toint() which casts from unsigned to int in such a way as to
avoid C undefined behaviour, since I'm not sure I trust compilers any
more to do the obviously sensible thing.
[originally from svn r9918]
changeset: 4618:3957829f24d3
user: Simon Tatham <[email protected]>
date: Mon Jul 08 22:36:04 2013 +0000
files: import.c sshdss.c sshrsa.c
description:
Add an assortment of extra safety checks.
[originally from svn r9896]
changeset: 4617:2cddee0bce12
user: Jacob Nevins <[email protected]>
date: Wed Dec 07 00:24:45 2005 +0000
files: import.c
description:
Institutional failure to memset() things pointed at rather than pointers.
Things should now be zeroed and memory not leaked. Spotted by Brant Thomsen.
[originally from svn r6476]
changeset: 4616:24ac78a9c71d
user: Simon Tatham <[email protected]>
date: Wed Feb 11 13:58:27 2004 +0000
files: import.c
description:
Jacob's last-minute testing found a couple of trivial bugs in
import.c, and my attempts to reproduce them in cmdgen found another
one there :-)
[originally from svn r3847]
changeset: 4615:088d39a73db0
user: Simon Tatham <[email protected]>
date: Thu Jan 22 18:52:49 2004 +0000
files: import.c
description:
Placate some gcc warnings.
[originally from svn r3761]
changeset: 4614:e4288bad4d93
parent: 1758:108b8924593d
user: Simon Tatham <[email protected]>
date: Fri Oct 03 21:21:23 2003 +0000
files: import.c
description:
My ASN.1 decoder returned wrong IDs for anything above 0x1E! Good
job it's never had to yet. Ahem.
[originally from svn r3479]
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Tue, 12 Jul 2016 23:00:01 +0800 |
parents | 9da3e7b4fe55 |
children | 750ec4ec4cbe b28624698130 |
line wrap: on
line source
/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "buffer.h" #include "dbutil.h" #include "bignum.h" #include "dbrandom.h" /* this is used to generate unique output from the same hashpool */ static uint32_t counter = 0; /* the max value for the counter, so it won't integer overflow */ #define MAX_COUNTER (1<<30) static unsigned char hashpool[SHA1_HASH_SIZE] = {0}; static int donerandinit = 0; #define INIT_SEED_SIZE 32 /* 256 bits */ /* The basic setup is we read some data from /dev/(u)random or prngd and hash it * into hashpool. To read data, we hash together current hashpool contents, * and a counter. We feed more data in by hashing the current pool and new * data into the pool. * * It is important to ensure that counter doesn't wrap around before we * feed in new entropy. * */ /* Pass len=0 to hash an entire file */ static int process_file(hash_state *hs, const char *filename, unsigned int len, int prngd) { static int already_blocked = 0; int readfd; unsigned int readcount; int ret = DROPBEAR_FAILURE; #ifdef DROPBEAR_PRNGD_SOCKET if (prngd) { readfd = connect_unix(filename); } else #endif { readfd = open(filename, O_RDONLY); } if (readfd < 0) { goto out; } readcount = 0; while (len == 0 || readcount < len) { int readlen, wantread; unsigned char readbuf[4096]; if (!already_blocked && !prngd) { int res; struct timeval timeout; fd_set read_fds; timeout.tv_sec = 2; timeout.tv_usec = 0; FD_ZERO(&read_fds); FD_SET(readfd, &read_fds); res = select(readfd + 1, &read_fds, NULL, NULL, &timeout); if (res == 0) { dropbear_log(LOG_WARNING, "Warning: Reading the randomness source '%s' seems to have blocked.\nYou may need to find a better entropy source.", filename); already_blocked = 1; } } if (len == 0) { wantread = sizeof(readbuf); } else { wantread = MIN(sizeof(readbuf), len-readcount); } #ifdef DROPBEAR_PRNGD_SOCKET if (prngd) { char egdcmd[2]; egdcmd[0] = 0x02; /* blocking read */ egdcmd[1] = (unsigned char)wantread; if (write(readfd, egdcmd, 2) < 0) { dropbear_exit("Can't send command to egd"); } } #endif readlen = read(readfd, readbuf, wantread); if (readlen <= 0) { if (readlen < 0 && errno == EINTR) { continue; } if (readlen == 0 && len == 0) { /* whole file was read as requested */ break; } goto out; } sha1_process(hs, readbuf, readlen); readcount += readlen; } ret = DROPBEAR_SUCCESS; out: close(readfd); return ret; } void addrandom(unsigned char * buf, unsigned int len) { hash_state hs; /* hash in the new seed data */ sha1_init(&hs); /* existing state (zeroes on startup) */ sha1_process(&hs, (void*)hashpool, sizeof(hashpool)); /* new */ sha1_process(&hs, buf, len); sha1_done(&hs, hashpool); } static void write_urandom() { #ifndef DROPBEAR_PRNGD_SOCKET /* This is opportunistic, don't worry about failure */ unsigned char buf[INIT_SEED_SIZE]; FILE *f = fopen(DROPBEAR_URANDOM_DEV, "w"); if (!f) { return; } genrandom(buf, sizeof(buf)); fwrite(buf, sizeof(buf), 1, f); fclose(f); #endif } /* Initialise the prng from /dev/urandom or prngd. This function can * be called multiple times */ void seedrandom() { hash_state hs; pid_t pid; struct timeval tv; clock_t clockval; /* hash in the new seed data */ sha1_init(&hs); /* existing state */ sha1_process(&hs, (void*)hashpool, sizeof(hashpool)); #ifdef DROPBEAR_PRNGD_SOCKET if (process_file(&hs, DROPBEAR_PRNGD_SOCKET, INIT_SEED_SIZE, 1) != DROPBEAR_SUCCESS) { dropbear_exit("Failure reading random device %s", DROPBEAR_PRNGD_SOCKET); } #else /* non-blocking random source (probably /dev/urandom) */ if (process_file(&hs, DROPBEAR_URANDOM_DEV, INIT_SEED_SIZE, 0) != DROPBEAR_SUCCESS) { dropbear_exit("Failure reading random device %s", DROPBEAR_URANDOM_DEV); } #endif /* A few other sources to fall back on. * Add more here for other platforms */ #ifdef __linux__ /* Seems to be a reasonable source of entropy from timers. Possibly hard * for even local attackers to reproduce */ process_file(&hs, "/proc/timer_list", 0, 0); /* Might help on systems with wireless */ process_file(&hs, "/proc/interrupts", 0, 0); process_file(&hs, "/proc/loadavg", 0, 0); process_file(&hs, "/proc/sys/kernel/random/entropy_avail", 0, 0); /* Mostly network visible but useful in some situations. * Limit size to avoid slowdowns on systems with lots of routes */ process_file(&hs, "/proc/net/netstat", 4096, 0); process_file(&hs, "/proc/net/dev", 4096, 0); process_file(&hs, "/proc/net/tcp", 4096, 0); /* Also includes interface lo */ process_file(&hs, "/proc/net/rt_cache", 4096, 0); process_file(&hs, "/proc/vmstat", 0, 0); #endif pid = getpid(); sha1_process(&hs, (void*)&pid, sizeof(pid)); /* gettimeofday() doesn't completely fill out struct timeval on OS X (10.8.3), avoid valgrind warnings by clearing it first */ memset(&tv, 0x0, sizeof(tv)); gettimeofday(&tv, NULL); sha1_process(&hs, (void*)&tv, sizeof(tv)); clockval = clock(); sha1_process(&hs, (void*)&clockval, sizeof(clockval)); /* When a private key is read by the client or server it will * be added to the hashpool - see runopts.c */ sha1_done(&hs, hashpool); counter = 0; donerandinit = 1; /* Feed it all back into /dev/urandom - this might help if Dropbear * is running from inetd and gets new state each time */ write_urandom(); } /* return len bytes of pseudo-random data */ void genrandom(unsigned char* buf, unsigned int len) { hash_state hs; unsigned char hash[SHA1_HASH_SIZE]; unsigned int copylen; if (!donerandinit) { dropbear_exit("seedrandom not done"); } while (len > 0) { sha1_init(&hs); sha1_process(&hs, (void*)hashpool, sizeof(hashpool)); sha1_process(&hs, (void*)&counter, sizeof(counter)); sha1_done(&hs, hash); counter++; if (counter > MAX_COUNTER) { seedrandom(); } copylen = MIN(len, SHA1_HASH_SIZE); memcpy(buf, hash, copylen); len -= copylen; buf += copylen; } m_burn(hash, sizeof(hash)); } /* Generates a random mp_int. * max is a *mp_int specifying an upper bound. * rand must be an initialised *mp_int for the result. * the result rand satisfies: 0 < rand < max * */ void gen_random_mpint(mp_int *max, mp_int *rand) { unsigned char *randbuf = NULL; unsigned int len = 0; const unsigned char masks[] = {0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f}; const int size_bits = mp_count_bits(max); len = size_bits / 8; if ((size_bits % 8) != 0) { len += 1; } randbuf = (unsigned char*)m_malloc(len); do { genrandom(randbuf, len); /* Mask out the unrequired bits - mp_read_unsigned_bin expects * MSB first.*/ randbuf[0] &= masks[size_bits % 8]; bytes_to_mp(rand, randbuf, len); /* keep regenerating until we get one satisfying * 0 < rand < max */ } while (!(mp_cmp(rand, max) == MP_LT && mp_cmp_d(rand, 0) == MP_GT)); m_burn(randbuf, len); m_free(randbuf); }