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/*
* (C) 2006, 2007 Andreas Gruenbacher <agruen@suse.de>
* Copyright (c) 2003-2008 Novell, Inc. (All rights reserved)
* Copyright 2009-2012 Canonical Ltd.
*
* The libapparmor library is licensed under the terms of the GNU
* Lesser General Public License, version 2.1. Please see the file
* COPYING.LGPL.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* Create a compressed hfa from and hfa
*/
#include <map>
#include <vector>
#include <ostream>
#include <iostream>
#include <fstream>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include "hfa.h"
#include "chfa.h"
#include "../immunix.h"
#include "flex-tables.h"
void CHFA::init_free_list(vector<pair<size_t, size_t> > &free_list,
size_t prev, size_t start)
{
for (size_t i = start; i < free_list.size(); i++) {
if (prev)
free_list[prev].second = i;
free_list[i].first = prev;
prev = i;
}
free_list[free_list.size() - 1].second = 0;
}
/**
* new Construct the transition table.
*/
CHFA::CHFA(DFA &dfa, map<uchar, uchar> &eq, dfaflags_t flags): eq(eq)
{
if (flags & DFA_DUMP_TRANS_PROGRESS)
fprintf(stderr, "Compressing HFA:\r");
if (dfa.diffcount)
chfaflags = YYTH_FLAG_DIFF_ENCODE;
else
chfaflags = 0;
if (eq.empty())
max_eq = 255;
else {
max_eq = 0;
for (map<uchar, uchar>::iterator i = eq.begin();
i != eq.end(); i++) {
if (i->second > max_eq)
max_eq = i->second;
}
}
/* Do initial setup adding up all the transitions and sorting by
* transition count.
*/
size_t optimal = 2;
multimap<size_t, State *> order;
vector<pair<size_t, size_t> > free_list;
for (Partition::iterator i = dfa.states.begin(); i != dfa.states.end(); i++) {
if (*i == dfa.start || *i == dfa.nonmatching)
continue;
optimal += (*i)->trans.size();
if (flags & DFA_CONTROL_TRANS_HIGH) {
size_t range = 0;
if ((*i)->trans.size())
range =
(*i)->trans.rbegin()->first -
(*i)->trans.begin()->first;
size_t ord = ((256 - (*i)->trans.size()) << 8) | (256 - range);
/* reverse sort by entry count, most entries first */
order.insert(make_pair(ord, *i));
}
}
/* Insert the dummy nonmatching transition by hand */
next_check.push_back(make_pair(dfa.nonmatching, dfa.nonmatching));
default_base.push_back(make_pair(dfa.nonmatching, 0));
num.insert(make_pair(dfa.nonmatching, num.size()));
accept.resize(max(dfa.states.size(), (size_t) 2));
accept2.resize(max(dfa.states.size(), (size_t) 2));
next_check.resize(max(optimal, (size_t) 256));
free_list.resize(next_check.size());
accept[0] = 0;
accept2[0] = 0;
first_free = 1;
init_free_list(free_list, 0, 1);
insert_state(free_list, dfa.start, dfa);
accept[1] = 0;
accept2[1] = 0;
num.insert(make_pair(dfa.start, num.size()));
int count = 2;
if (!(flags & DFA_CONTROL_TRANS_HIGH)) {
for (Partition::iterator i = dfa.states.begin(); i != dfa.states.end(); i++) {
if (*i != dfa.nonmatching && *i != dfa.start) {
insert_state(free_list, *i, dfa);
accept[num.size()] = (*i)->perms.allow;
accept2[num.size()] = PACK_AUDIT_CTL((*i)->perms.audit, (*i)->perms.quiet & (*i)->perms.deny);
num.insert(make_pair(*i, num.size()));
}
if (flags & (DFA_DUMP_TRANS_PROGRESS)) {
count++;
if (count % 100 == 0)
fprintf(stderr, "\033[2KCompressing trans table: insert state: %d/%zd\r",
count, dfa.states.size());
}
}
} else {
for (multimap<size_t, State *>::iterator i = order.begin();
i != order.end(); i++) {
if (i->second != dfa.nonmatching &&
i->second != dfa.start) {
insert_state(free_list, i->second, dfa);
accept[num.size()] = i->second->perms.allow;
accept2[num.size()] = PACK_AUDIT_CTL(i->second->perms.audit, i->second->perms.quiet & i->second->perms.deny);
num.insert(make_pair(i->second, num.size()));
}
if (flags & (DFA_DUMP_TRANS_PROGRESS)) {
count++;
if (count % 100 == 0)
fprintf(stderr, "\033[2KCompressing trans table: insert state: %d/%zd\r",
count, dfa.states.size());
}
}
}
if (flags & (DFA_DUMP_TRANS_STATS | DFA_DUMP_TRANS_PROGRESS)) {
ssize_t size = 4 * next_check.size() + 6 * dfa.states.size();
fprintf(stderr, "\033[2KCompressed trans table: states %zd, next/check %zd, optimal next/check %zd avg/state %.2f, compression %zd/%zd = %.2f %%\n",
dfa.states.size(), next_check.size(), optimal,
(float)next_check.size() / (float)dfa.states.size(),
size, 512 * dfa.states.size(),
100.0 - ((float)size * 100.0 /(float)(512 * dfa.states.size())));
}
}
/**
* Does <trans> fit into position <base> of the transition table?
*/
bool CHFA::fits_in(vector<pair<size_t, size_t> > &free_list
__attribute__ ((unused)), size_t pos,
StateTrans &trans)
{
size_t c, base = pos - trans.begin()->first;
for (StateTrans::iterator i = trans.begin(); i != trans.end(); i++) {
c = base + i->first;
/* if it overflows the next_check array it fits in as we will
* resize */
if (c >= next_check.size())
return true;
if (next_check[c].second)
return false;
}
return true;
}
/**
* Insert <state> of <dfa> into the transition table.
*/
void CHFA::insert_state(vector<pair<size_t, size_t> > &free_list,
State *from, DFA &dfa)
{
State *default_state = dfa.nonmatching;
size_t base = 0;
int resize;
StateTrans &trans = from->trans;
size_t c = trans.begin()->first;
size_t prev = 0;
size_t x = first_free;
if (from->otherwise)
default_state = from->otherwise;
if (trans.empty())
goto do_insert;
repeat:
resize = 0;
/* get the first free entry that won't underflow */
while (x && (x < c)) {
prev = x;
x = free_list[x].second;
}
/* try inserting until we succeed. */
while (x && !fits_in(free_list, x, trans)) {
prev = x;
x = free_list[x].second;
}
if (!x) {
resize = 256 - trans.begin()->first;
x = free_list.size();
/* set prev to last free */
} else if (x + 255 - trans.begin()->first >= next_check.size()) {
resize = (255 - trans.begin()->first - (next_check.size() - 1 - x));
for (size_t y = x; y; y = free_list[y].second)
prev = y;
}
if (resize) {
/* expand next_check and free_list */
size_t old_size = free_list.size();
next_check.resize(next_check.size() + resize);
free_list.resize(free_list.size() + resize);
init_free_list(free_list, prev, old_size);
if (!first_free)
first_free = old_size;;
if (x == old_size)
goto repeat;
}
base = x - c;
for (StateTrans::iterator j = trans.begin(); j != trans.end(); j++) {
next_check[base + j->first] = make_pair(j->second, from);
size_t prev = free_list[base + j->first].first;
size_t next = free_list[base + j->first].second;
if (prev)
free_list[prev].second = next;
if (next)
free_list[next].first = prev;
if (base + j->first == first_free)
first_free = next;
}
do_insert:
if (from->flags & DiffEncodeFlag)
base |= DiffEncodeBit32;
default_base.push_back(make_pair(default_state, base));
}
/**
* Text-dump the transition table (for debugging).
*/
void CHFA::dump(ostream &os)
{
map<size_t, const State *> st;
for (map<const State *, size_t>::iterator i = num.begin(); i != num.end(); i++) {
st.insert(make_pair(i->second, i->first));
}
os << "size=" << default_base.size() << " (accept, default, base): {state} -> {default state}" << "\n";
for (size_t i = 0; i < default_base.size(); i++) {
os << i << ": ";
os << "(" << accept[i] << ", " << num[default_base[i].first]
<< ", " << default_base[i].second << ")";
if (st[i])
os << " " << *st[i];
if (default_base[i].first)
os << " -> " << *default_base[i].first;
os << "\n";
}
os << "size=" << next_check.size() << " (next, check): {check state} -> {next state} : offset from base\n";
for (size_t i = 0; i < next_check.size(); i++) {
if (!next_check[i].second)
continue;
os << i << ": ";
if (next_check[i].second) {
os << "(" << num[next_check[i].first] << ", "
<< num[next_check[i].second] << ")" << " "
<< *next_check[i].second << " -> "
<< *next_check[i].first << ": ";
size_t offs = i - base_mask_size(default_base[num[next_check[i].second]].second);
if (eq.size())
os << offs;
else
os << (uchar) offs;
}
os << "\n";
}
}
/**
* Create a flex-style binary dump of the DFA tables. The table format
* was partly reverse engineered from the flex sources and from
* examining the tables that flex creates with its --tables-file option.
* (Only the -Cf and -Ce formats are currently supported.)
*/
#define YYTH_REGEX_MAGIC 0x1B5E783D
static inline size_t pad64(size_t i)
{
return (i + (size_t) 7) & ~(size_t) 7;
}
string fill64(size_t i)
{
const char zeroes[8] = { };
string fill(zeroes, (i & 7) ? 8 - (i & 7) : 0);
return fill;
}
template<class Iter> size_t flex_table_size(Iter pos, Iter end)
{
return pad64(sizeof(struct table_header) + sizeof(*pos) * (end - pos));
}
template<class Iter>
void write_flex_table(ostream &os, int id, Iter pos, Iter end)
{
struct table_header td = { 0, 0, 0, 0 };
size_t size = end - pos;
td.td_id = htons(id);
td.td_flags = htons(sizeof(*pos));
td.td_lolen = htonl(size);
os.write((char *)&td, sizeof(td));
for (; pos != end; ++pos) {
switch (sizeof(*pos)) {
case 4:
os.put((char)(*pos >> 24));
os.put((char)(*pos >> 16));
case 2:
os.put((char)(*pos >> 8));
case 1:
os.put((char)*pos);
}
}
os << fill64(sizeof(td) + sizeof(*pos) * size);
}
void CHFA::flex_table(ostream &os, const char *name)
{
const char th_version[] = "notflex";
struct table_set_header th = { 0, 0, 0, 0 };
/**
* Change the following two data types to adjust the maximum flex
* table size.
*/
typedef uint16_t state_t;
typedef uint32_t trans_t;
if (default_base.size() >= (state_t) - 1) {
cerr << "Too many states (" << default_base.size() << ") for "
"type state_t\n";
exit(1);
}
if (next_check.size() >= (trans_t) - 1) {
cerr << "Too many transitions (" << next_check.size()
<< ") for " "type trans_t\n";
exit(1);
}
/**
* Create copies of the data structures so that we can dump the tables
* using the generic write_flex_table() routine.
*/
vector<uint8_t> equiv_vec;
if (eq.size()) {
equiv_vec.resize(256);
for (map<uchar, uchar>::iterator i = eq.begin(); i != eq.end(); i++) {
equiv_vec[i->first] = i->second;
}
}
vector<state_t> default_vec;
vector<trans_t> base_vec;
for (DefaultBase::iterator i = default_base.begin(); i != default_base.end(); i++) {
default_vec.push_back(num[i->first]);
base_vec.push_back(i->second);
}
vector<state_t> next_vec;
vector<state_t> check_vec;
for (NextCheck::iterator i = next_check.begin(); i != next_check.end(); i++) {
next_vec.push_back(num[i->first]);
check_vec.push_back(num[i->second]);
}
/* Write the actual flex parser table. */
size_t hsize = pad64(sizeof(th) + sizeof(th_version) + strlen(name) + 1);
th.th_magic = htonl(YYTH_REGEX_MAGIC);
th.th_flags = htonl(chfaflags);
th.th_hsize = htonl(hsize);
th.th_ssize = htonl(hsize +
flex_table_size(accept.begin(), accept.end()) +
flex_table_size(accept2.begin(), accept2.end()) +
(eq.size() ? flex_table_size(equiv_vec.begin(), equiv_vec.end()) : 0) +
flex_table_size(base_vec.begin(), base_vec.end()) +
flex_table_size(default_vec.begin(), default_vec.end()) +
flex_table_size(next_vec.begin(), next_vec.end()) +
flex_table_size(check_vec.begin(), check_vec.end()));
os.write((char *)&th, sizeof(th));
os << th_version << (char)0 << name << (char)0;
os << fill64(sizeof(th) + sizeof(th_version) + strlen(name) + 1);
write_flex_table(os, YYTD_ID_ACCEPT, accept.begin(), accept.end());
write_flex_table(os, YYTD_ID_ACCEPT2, accept2.begin(), accept2.end());
if (eq.size())
write_flex_table(os, YYTD_ID_EC, equiv_vec.begin(),
equiv_vec.end());
write_flex_table(os, YYTD_ID_BASE, base_vec.begin(), base_vec.end());
write_flex_table(os, YYTD_ID_DEF, default_vec.begin(), default_vec.end());
write_flex_table(os, YYTD_ID_NXT, next_vec.begin(), next_vec.end());
write_flex_table(os, YYTD_ID_CHK, check_vec.begin(), check_vec.end());
}
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