X-Git-Url: https://git.stg.codes/stg.git/blobdiff_plain/b27841d687ec9e84983340b5581376dfb24010ea..b2b89723a2427bba8290bd6967a1ab39cbb630be:/libs/smux/per_support.c diff --git a/libs/smux/per_support.c b/libs/smux/per_support.c index 14b4c4c7..8f4d4604 100644 --- a/libs/smux/per_support.c +++ b/libs/smux/per_support.c @@ -1,190 +1,46 @@ /* - * Copyright (c) 2005-2014 Lev Walkin . - * All rights reserved. + * Copyright (c) 2005-2017 Lev Walkin . All rights reserved. * Redistribution and modifications are permitted subject to BSD license. */ #include #include #include -char * -per_data_string(asn_per_data_t *pd) { - static char buf[2][32]; - static int n; - n = (n+1) % 2; - snprintf(buf[n], sizeof(buf[n]), - "{m=%ld span %+ld[%d..%d] (%d)}", - (long)pd->moved, - (((long)pd->buffer) & 0xf), - (int)pd->nboff, (int)pd->nbits, - (int)(pd->nbits - pd->nboff)); - return buf[n]; -} - -void -per_get_undo(asn_per_data_t *pd, int nbits) { - if((ssize_t)pd->nboff < nbits) { - assert((ssize_t)pd->nboff < nbits); - } else { - pd->nboff -= nbits; - pd->moved -= nbits; - } -} - -/* - * Extract a small number of bits (<= 31) from the specified PER data pointer. - */ -int32_t -per_get_few_bits(asn_per_data_t *pd, int nbits) { - size_t off; /* Next after last bit offset */ - ssize_t nleft; /* Number of bits left in this stream */ - uint32_t accum; - const uint8_t *buf; - - if(nbits < 0) - return -1; - - nleft = pd->nbits - pd->nboff; - if(nbits > nleft) { - int32_t tailv, vhead; - if(!pd->refill || nbits > 31) return -1; - /* Accumulate unused bytes before refill */ - ASN_DEBUG("Obtain the rest %d bits (want %d)", - (int)nleft, (int)nbits); - tailv = per_get_few_bits(pd, nleft); - if(tailv < 0) return -1; - /* Refill (replace pd contents with new data) */ - if(pd->refill(pd)) - return -1; - nbits -= nleft; - vhead = per_get_few_bits(pd, nbits); - /* Combine the rest of previous pd with the head of new one */ - tailv = (tailv << nbits) | vhead; /* Could == -1 */ - return tailv; - } - - /* - * Normalize position indicator. - */ - if(pd->nboff >= 8) { - pd->buffer += (pd->nboff >> 3); - pd->nbits -= (pd->nboff & ~0x07); - pd->nboff &= 0x07; - } - pd->moved += nbits; - pd->nboff += nbits; - off = pd->nboff; - buf = pd->buffer; - - /* - * Extract specified number of bits. - */ - if(off <= 8) - accum = nbits ? (buf[0]) >> (8 - off) : 0; - else if(off <= 16) - accum = ((buf[0] << 8) + buf[1]) >> (16 - off); - else if(off <= 24) - accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off); - else if(off <= 31) - accum = ((buf[0] << 24) + (buf[1] << 16) - + (buf[2] << 8) + (buf[3])) >> (32 - off); - else if(nbits <= 31) { - asn_per_data_t tpd = *pd; - /* Here are we with our 31-bits limit plus 1..7 bits offset. */ - per_get_undo(&tpd, nbits); - /* The number of available bits in the stream allow - * for the following operations to take place without - * invoking the ->refill() function */ - accum = per_get_few_bits(&tpd, nbits - 24) << 24; - accum |= per_get_few_bits(&tpd, 24); - } else { - per_get_undo(pd, nbits); - return -1; - } - - accum &= (((uint32_t)1 << nbits) - 1); - - ASN_DEBUG(" [PER got %2d<=%2d bits => span %d %+ld[%d..%d]:%02x (%d) => 0x%x]", - (int)nbits, (int)nleft, - (int)pd->moved, - (((long)pd->buffer) & 0xf), - (int)pd->nboff, (int)pd->nbits, - ((pd->buffer != NULL)?pd->buffer[0]:0), - (int)(pd->nbits - pd->nboff), - (int)accum); - - return accum; -} - /* - * Extract a large number of bits from the specified PER data pointer. - */ -int -per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int alright, int nbits) { - int32_t value; - - if(alright && (nbits & 7)) { - /* Perform right alignment of a first few bits */ - value = per_get_few_bits(pd, nbits & 0x07); - if(value < 0) return -1; - *dst++ = value; /* value is already right-aligned */ - nbits &= ~7; - } - - while(nbits) { - if(nbits >= 24) { - value = per_get_few_bits(pd, 24); - if(value < 0) return -1; - *(dst++) = value >> 16; - *(dst++) = value >> 8; - *(dst++) = value; - nbits -= 24; - } else { - value = per_get_few_bits(pd, nbits); - if(value < 0) return -1; - if(nbits & 7) { /* implies left alignment */ - value <<= 8 - (nbits & 7), - nbits += 8 - (nbits & 7); - if(nbits > 24) - *dst++ = value >> 24; - } - if(nbits > 16) - *dst++ = value >> 16; - if(nbits > 8) - *dst++ = value >> 8; - *dst++ = value; - break; - } - } - - return 0; -} - -/* - * Get the length "n" from the stream. + * X.691-201508 #10.9 General rules for encoding a length determinant. + * Get the optionally constrained length "n" from the stream. */ ssize_t -uper_get_length(asn_per_data_t *pd, int ebits, int *repeat) { - ssize_t value; +uper_get_length(asn_per_data_t *pd, int ebits, size_t lower_bound, + int *repeat) { + ssize_t value; - *repeat = 0; + *repeat = 0; - if(ebits >= 0) return per_get_few_bits(pd, ebits); + /* #11.9.4.1 Encoding if constrained (according to effective bits) */ + if(ebits >= 0 && ebits <= 16) { + value = per_get_few_bits(pd, ebits); + if(value >= 0) value += lower_bound; + return value; + } value = per_get_few_bits(pd, 8); - if(value < 0) return -1; - if((value & 128) == 0) /* #10.9.3.6 */ - return (value & 0x7F); - if((value & 64) == 0) { /* #10.9.3.7 */ - value = ((value & 63) << 8) | per_get_few_bits(pd, 8); - if(value < 0) return -1; - return value; - } - value &= 63; /* this is "m" from X.691, #10.9.3.8 */ - if(value < 1 || value > 4) - return -1; - *repeat = 1; - return (16384 * value); + if((value & 0x80) == 0) { /* #11.9.3.6 */ + return (value & 0x7F); + } else if((value & 0x40) == 0) { /* #11.9.3.7 */ + /* bit 8 ... set to 1 and bit 7 ... set to zero */ + value = ((value & 0x3f) << 8) | per_get_few_bits(pd, 8); + return value; /* potential -1 from per_get_few_bits passes through. */ + } else if(value < 0) { + ASN_DEBUG("END of stream reached for PER"); + return -1; + } + value &= 0x3f; /* this is "m" from X.691, #11.9.3.8 */ + if(value < 1 || value > 4) { + return -1; /* Prohibited by #11.9.3.8 */ + } + *repeat = 1; + return (16384 * value); } /* @@ -205,7 +61,7 @@ uper_get_nslength(asn_per_data_t *pd) { return length; } else { int repeat; - length = uper_get_length(pd, -1, &repeat); + length = uper_get_length(pd, -1, 0, &repeat); if(length >= 0 && !repeat) return length; return -1; /* Error, or do not support >16K extensions */ } @@ -291,171 +147,48 @@ int uper_get_constrained_whole_number(asn_per_data_t *pd, unsigned long *out_val /* X.691-2008/11, #11.5.6 -> #11.3 */ -int uper_put_constrained_whole_number_s(asn_per_outp_t *po, long v, int nbits) { - /* - * Assume signed number can be safely coerced into - * unsigned of the same range. - * The following testing code will likely be optimized out - * by compiler if it is true. - */ - unsigned long uvalue1 = ULONG_MAX; - long svalue = uvalue1; - unsigned long uvalue2 = svalue; - assert(uvalue1 == uvalue2); - return uper_put_constrained_whole_number_u(po, v, nbits); -} - -int uper_put_constrained_whole_number_u(asn_per_outp_t *po, unsigned long v, int nbits) { - if(nbits <= 31) { - return per_put_few_bits(po, v, nbits); - } else { - /* Put higher portion first, followed by lower 31-bit */ - if(uper_put_constrained_whole_number_u(po, v >> 31, nbits - 31)) - return -1; - return per_put_few_bits(po, v, 31); - } -} - -/* - * Put a small number of bits (<= 31). - */ int -per_put_few_bits(asn_per_outp_t *po, uint32_t bits, int obits) { - size_t off; /* Next after last bit offset */ - size_t omsk; /* Existing last byte meaningful bits mask */ - uint8_t *buf; - - if(obits <= 0 || obits >= 32) return obits ? -1 : 0; - - ASN_DEBUG("[PER put %d bits %x to %p+%d bits]", - obits, (int)bits, po->buffer, (int)po->nboff); - - /* - * Normalize position indicator. - */ - if(po->nboff >= 8) { - po->buffer += (po->nboff >> 3); - po->nbits -= (po->nboff & ~0x07); - po->nboff &= 0x07; - } - - /* - * Flush whole-bytes output, if necessary. - */ - if(po->nboff + obits > po->nbits) { - int complete_bytes = (po->buffer - po->tmpspace); - ASN_DEBUG("[PER output %ld complete + %ld]", - (long)complete_bytes, (long)po->flushed_bytes); - if(po->outper(po->tmpspace, complete_bytes, po->op_key) < 0) - return -1; - if(po->nboff) - po->tmpspace[0] = po->buffer[0]; - po->buffer = po->tmpspace; - po->nbits = 8 * sizeof(po->tmpspace); - po->flushed_bytes += complete_bytes; - } - - /* - * Now, due to sizeof(tmpspace), we are guaranteed large enough space. - */ - buf = po->buffer; - omsk = ~((1 << (8 - po->nboff)) - 1); - off = (po->nboff + obits); - - /* Clear data of debris before meaningful bits */ - bits &= (((uint32_t)1 << obits) - 1); - - ASN_DEBUG("[PER out %d %u/%x (t=%d,o=%d) %x&%x=%x]", obits, - (int)bits, (int)bits, - (int)po->nboff, (int)off, - buf[0], (int)(omsk&0xff), - (int)(buf[0] & omsk)); - - if(off <= 8) /* Completely within 1 byte */ - po->nboff = off, - bits <<= (8 - off), - buf[0] = (buf[0] & omsk) | bits; - else if(off <= 16) - po->nboff = off, - bits <<= (16 - off), - buf[0] = (buf[0] & omsk) | (bits >> 8), - buf[1] = bits; - else if(off <= 24) - po->nboff = off, - bits <<= (24 - off), - buf[0] = (buf[0] & omsk) | (bits >> 16), - buf[1] = bits >> 8, - buf[2] = bits; - else if(off <= 31) - po->nboff = off, - bits <<= (32 - off), - buf[0] = (buf[0] & omsk) | (bits >> 24), - buf[1] = bits >> 16, - buf[2] = bits >> 8, - buf[3] = bits; - else { - per_put_few_bits(po, bits >> (obits - 24), 24); - per_put_few_bits(po, bits, obits - 24); - } - - ASN_DEBUG("[PER out %u/%x => %02x buf+%ld]", - (int)bits, (int)bits, buf[0], - (long)(po->buffer - po->tmpspace)); - - return 0; -} - - -/* - * Output a large number of bits. - */ -int -per_put_many_bits(asn_per_outp_t *po, const uint8_t *src, int nbits) { - - while(nbits) { - uint32_t value; - - if(nbits >= 24) { - value = (src[0] << 16) | (src[1] << 8) | src[2]; - src += 3; - nbits -= 24; - if(per_put_few_bits(po, value, 24)) - return -1; - } else { - value = src[0]; - if(nbits > 8) - value = (value << 8) | src[1]; - if(nbits > 16) - value = (value << 8) | src[2]; - if(nbits & 0x07) - value >>= (8 - (nbits & 0x07)); - if(per_put_few_bits(po, value, nbits)) - return -1; - break; - } - } - - return 0; +uper_put_constrained_whole_number_u(asn_per_outp_t *po, unsigned long v, + int nbits) { + if(nbits <= 31) { + return per_put_few_bits(po, v, nbits); + } else { + /* Put higher portion first, followed by lower 31-bit */ + if(uper_put_constrained_whole_number_u(po, v >> 31, nbits - 31)) + return -1; + return per_put_few_bits(po, v, 31); + } } /* + * X.691 (08/2015) #11.9 "General rules for encoding a length determinant" * Put the length "n" (or part of it) into the stream. */ ssize_t -uper_put_length(asn_per_outp_t *po, size_t length) { - - if(length <= 127) /* #10.9.3.6 */ - return per_put_few_bits(po, length, 8) - ? -1 : (ssize_t)length; - else if(length < 16384) /* #10.9.3.7 */ - return per_put_few_bits(po, length|0x8000, 16) - ? -1 : (ssize_t)length; - - length >>= 14; - if(length > 4) length = 4; +uper_put_length(asn_per_outp_t *po, size_t length, int *need_eom) { + int dummy = 0; + if(!need_eom) need_eom = &dummy; + + if(length <= 127) { /* #11.9.3.6 */ + *need_eom = 0; + return per_put_few_bits(po, length, 8) + ? -1 : (ssize_t)length; + } else if(length < 16384) { /* #10.9.3.7 */ + *need_eom = 0; + return per_put_few_bits(po, length|0x8000, 16) + ? -1 : (ssize_t)length; + } + + *need_eom = 0 == (length & 16383); + length >>= 14; + if(length > 4) { + *need_eom = 0; + length = 4; + } + + return per_put_few_bits(po, 0xC0 | length, 8) + ? -1 : (ssize_t)(length << 14); - return per_put_few_bits(po, 0xC0 | length, 8) - ? -1 : (ssize_t)(length << 14); } @@ -466,18 +199,97 @@ uper_put_length(asn_per_outp_t *po, size_t length) { */ int uper_put_nslength(asn_per_outp_t *po, size_t length) { + if(length <= 64) { + /* #11.9.3.4 */ + if(length == 0) return -1; + return per_put_few_bits(po, length - 1, 7) ? -1 : 0; + } else { + int need_eom = 0; + if(uper_put_length(po, length, &need_eom) != (ssize_t)length + || need_eom) { + /* This might happen in case of >16K extensions */ + return -1; + } + } + + return 0; +} - if(length <= 64) { - /* #10.9.3.4 */ - if(length == 0) return -1; - return per_put_few_bits(po, length-1, 7) ? -1 : 0; - } else { - if(uper_put_length(po, length) != (ssize_t)length) { - /* This might happen in case of >16K extensions */ - return -1; - } - } +static int +per__long_range(long lb, long ub, unsigned long *range_r) { + unsigned long bounds_range; + if((ub < 0) == (lb < 0)) { + bounds_range = ub - lb; + } else if(lb < 0) { + assert(ub >= 0); + bounds_range = 1 + ((unsigned long)ub + (unsigned long)-(lb + 1)); + } else { + assert(!"Unreachable"); + return -1; + } + *range_r = bounds_range; + return 0; +} - return 0; +int +per_long_range_rebase(long v, long lb, long ub, unsigned long *output) { + unsigned long range; + + assert(lb <= ub); + + if(v < lb || v > ub || per__long_range(lb, ub, &range) < 0) { + /* Range error. */ + return -1; + } + + /* + * Fundamentally what we're doing is returning (v-lb). + * However, this triggers undefined behavior when the word width + * of signed (v) is the same as the size of unsigned (*output). + * In practice, it triggers the UndefinedSanitizer. Therefore we shall + * compute the ranges accurately to avoid C's undefined behavior. + */ + if((v < 0) == (lb < 0)) { + *output = v-lb; + return 0; + } else if(v < 0) { + unsigned long rebased = 1 + (unsigned long)-(v+1) + (unsigned long)lb; + assert(rebased <= range); /* By construction */ + *output = rebased; + return 0; + } else if(lb < 0) { + unsigned long rebased = 1 + (unsigned long)-(lb+1) + (unsigned long)v; + assert(rebased <= range); /* By construction */ + *output = rebased; + return 0; + } else { + assert(!"Unreachable"); + return -1; + } } +int +per_long_range_unrebase(unsigned long inp, long lb, long ub, long *outp) { + unsigned long range; + + if(per__long_range(lb, ub, &range) != 0) { + return -1; + } + + if(inp > range) { + /* + * We can encode something in the given number of bits that technically + * exceeds the range. This is an avenue for security errors, + * so we don't allow that. + */ + return -1; + } + + if(inp <= LONG_MAX) { + *outp = (long)inp + lb; + } else { + *outp = (lb + LONG_MAX + 1) + (long)((inp - LONG_MAX) - 1); + } + + return 0; +}