Mercurial > dropbear
view buffer.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 | 6914eedb1072 |
children | 6fafb500de88 ce0931b7f4c2 |
line wrap: on
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/* * Dropbear SSH * * 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. */ /* Buffer handling routines, designed to avoid overflows/using invalid data */ #include "includes.h" #include "dbutil.h" #include "buffer.h" /* Prevent integer overflows when incrementing buffer position/length. * Calling functions should check arguments first, but this provides a * backstop */ #define BUF_MAX_INCR 1000000000 #define BUF_MAX_SIZE 1000000000 /* avoid excessively large numbers, > ~8192 bits */ #define BUF_MAX_MPINT (8240 / 8) /* Create (malloc) a new buffer of size */ buffer* buf_new(unsigned int size) { buffer* buf; if (size > BUF_MAX_SIZE) { dropbear_exit("buf->size too big"); } buf = (buffer*)m_malloc(sizeof(buffer)+size); if (size > 0) { buf->data = (unsigned char*)buf + sizeof(buffer); } else { buf->data = NULL; } buf->size = size; return buf; } /* free the buffer's data and the buffer itself */ void buf_free(buffer* buf) { m_free(buf); } /* overwrite the contents of the buffer to clear it */ void buf_burn(buffer* buf) { m_burn(buf->data, buf->size); } /* resize a buffer, pos and len will be repositioned if required when * downsizing */ buffer* buf_resize(buffer *buf, unsigned int newsize) { if (newsize > BUF_MAX_SIZE) { dropbear_exit("buf->size too big"); } buf = m_realloc(buf, sizeof(buffer)+newsize); buf->data = (unsigned char*)buf + sizeof(buffer); buf->size = newsize; buf->len = MIN(newsize, buf->len); buf->pos = MIN(newsize, buf->pos); return buf; } /* Create a copy of buf, allocating required memory etc. */ /* The new buffer is sized the same as the length of the source buffer. */ buffer* buf_newcopy(buffer* buf) { buffer* ret; ret = buf_new(buf->len); ret->len = buf->len; if (buf->len > 0) { memcpy(ret->data, buf->data, buf->len); } return ret; } /* Set the length of the buffer */ void buf_setlen(buffer* buf, unsigned int len) { if (len > buf->size) { dropbear_exit("Bad buf_setlen"); } buf->len = len; } /* Increment the length of the buffer */ void buf_incrlen(buffer* buf, unsigned int incr) { if (incr > BUF_MAX_INCR || buf->len + incr > buf->size) { dropbear_exit("Bad buf_incrlen"); } buf->len += incr; } /* Set the position of the buffer */ void buf_setpos(buffer* buf, unsigned int pos) { if (pos > buf->len) { dropbear_exit("Bad buf_setpos"); } buf->pos = pos; } /* increment the position by incr, increasing the buffer length if required */ void buf_incrwritepos(buffer* buf, unsigned int incr) { if (incr > BUF_MAX_INCR || buf->pos + incr > buf->size) { dropbear_exit("Bad buf_incrwritepos"); } buf->pos += incr; if (buf->pos > buf->len) { buf->len = buf->pos; } } /* increment the position by incr, negative values are allowed, to * decrement the pos*/ void buf_incrpos(buffer* buf, int incr) { if (incr > BUF_MAX_INCR || incr < -BUF_MAX_INCR || (unsigned int)((int)buf->pos + incr) > buf->len || ((int)buf->pos + incr) < 0) { dropbear_exit("Bad buf_incrpos"); } buf->pos += incr; } /* Get a byte from the buffer and increment the pos */ unsigned char buf_getbyte(buffer* buf) { /* This check is really just ==, but the >= allows us to check for the * bad case of pos > len, which should _never_ happen. */ if (buf->pos >= buf->len) { dropbear_exit("Bad buf_getbyte"); } return buf->data[buf->pos++]; } /* Get a bool from the buffer and increment the pos */ unsigned char buf_getbool(buffer* buf) { unsigned char b; b = buf_getbyte(buf); if (b != 0) b = 1; return b; } /* put a byte, incrementing the length if required */ void buf_putbyte(buffer* buf, unsigned char val) { if (buf->pos >= buf->len) { buf_incrlen(buf, 1); } buf->data[buf->pos] = val; buf->pos++; } /* returns an in-place pointer to the buffer, checking that * the next len bytes from that position can be used */ unsigned char* buf_getptr(buffer* buf, unsigned int len) { if (len > BUF_MAX_INCR || buf->pos + len > buf->len) { dropbear_exit("Bad buf_getptr"); } return &buf->data[buf->pos]; } /* like buf_getptr, but checks against total size, not used length. * This allows writing past the used length, but not past the size */ unsigned char* buf_getwriteptr(buffer* buf, unsigned int len) { if (len > BUF_MAX_INCR || buf->pos + len > buf->size) { dropbear_exit("Bad buf_getwriteptr"); } return &buf->data[buf->pos]; } /* Return a null-terminated string, it is malloced, so must be free()ed * Note that the string isn't checked for null bytes, hence the retlen * may be longer than what is returned by strlen */ char* buf_getstring(buffer* buf, unsigned int *retlen) { unsigned int len; char* ret; len = buf_getint(buf); if (len > MAX_STRING_LEN) { dropbear_exit("String too long"); } if (retlen != NULL) { *retlen = len; } ret = m_malloc(len+1); memcpy(ret, buf_getptr(buf, len), len); buf_incrpos(buf, len); ret[len] = '\0'; return ret; } /* Return a string as a newly allocated buffer */ buffer * buf_getstringbuf(buffer *buf) { buffer *ret = NULL; unsigned int len = buf_getint(buf); if (len > MAX_STRING_LEN) { dropbear_exit("String too long"); } ret = buf_new(len); memcpy(buf_getwriteptr(ret, len), buf_getptr(buf, len), len); buf_incrpos(buf, len); buf_incrlen(ret, len); return ret; } /* Just increment the buffer position the same as if we'd used buf_getstring, * but don't bother copying/malloc()ing for it */ void buf_eatstring(buffer *buf) { buf_incrpos( buf, buf_getint(buf) ); } /* Get an uint32 from the buffer and increment the pos */ unsigned int buf_getint(buffer* buf) { unsigned int ret; LOAD32H(ret, buf_getptr(buf, 4)); buf_incrpos(buf, 4); return ret; } /* put a 32bit uint into the buffer, incr bufferlen & pos if required */ void buf_putint(buffer* buf, int unsigned val) { STORE32H(val, buf_getwriteptr(buf, 4)); buf_incrwritepos(buf, 4); } /* put a SSH style string into the buffer, increasing buffer len if required */ void buf_putstring(buffer* buf, const char* str, unsigned int len) { buf_putint(buf, len); buf_putbytes(buf, (const unsigned char*)str, len); } /* puts an entire buffer as a SSH string. ignore pos of buf_str. */ void buf_putbufstring(buffer *buf, const buffer* buf_str) { buf_putstring(buf, (const char*)buf_str->data, buf_str->len); } /* put the set of len bytes into the buffer, incrementing the pos, increasing * len if required */ void buf_putbytes(buffer *buf, const unsigned char *bytes, unsigned int len) { memcpy(buf_getwriteptr(buf, len), bytes, len); buf_incrwritepos(buf, len); } /* for our purposes we only need positive (or 0) numbers, so will * fail if we get negative numbers */ void buf_putmpint(buffer* buf, mp_int * mp) { unsigned int len, pad = 0; TRACE2(("enter buf_putmpint")) dropbear_assert(mp != NULL); if (SIGN(mp) == MP_NEG) { dropbear_exit("negative bignum"); } /* zero check */ if (USED(mp) == 1 && DIGIT(mp, 0) == 0) { len = 0; } else { /* SSH spec requires padding for mpints with the MSB set, this code * implements it */ len = mp_count_bits(mp); /* if the top bit of MSB is set, we need to pad */ pad = (len%8 == 0) ? 1 : 0; len = len / 8 + 1; /* don't worry about rounding, we need it for padding anyway when len%8 == 0 */ } /* store the length */ buf_putint(buf, len); /* store the actual value */ if (len > 0) { if (pad) { buf_putbyte(buf, 0x00); } if (mp_to_unsigned_bin(mp, buf_getwriteptr(buf, len-pad)) != MP_OKAY) { dropbear_exit("mpint error"); } buf_incrwritepos(buf, len-pad); } TRACE2(("leave buf_putmpint")) } /* Retrieve an mp_int from the buffer. * Will fail for -ve since they shouldn't be required here. * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ int buf_getmpint(buffer* buf, mp_int* mp) { unsigned int len; len = buf_getint(buf); if (len == 0) { mp_zero(mp); return DROPBEAR_SUCCESS; } if (len > BUF_MAX_MPINT) { return DROPBEAR_FAILURE; } /* check for negative */ if (*buf_getptr(buf, 1) & (1 << (CHAR_BIT-1))) { return DROPBEAR_FAILURE; } if (mp_read_unsigned_bin(mp, buf_getptr(buf, len), len) != MP_OKAY) { return DROPBEAR_FAILURE; } buf_incrpos(buf, len); return DROPBEAR_SUCCESS; }