parser: add regex generator for range

Signed-off-by: Georgia Garcia <georgia.garcia@canonical.com>

parser/Makefile

@@ -107,7 +107,7 @@ STATIC_HDRS = af_rule.h af_unix.h capability.h common_optarg.h dbus.h \
        file_cache.h immunix.h lib.h mount.h network.h parser.h \
        parser_include.h parser_version.h policy_cache.h policydb.h \
        profile.h ptrace.h rule.h signal.h userns.h mqueue.h io_uring.h \
-       common_flags.h
+       common_flags.h bignum.h
 
 SPECIAL_HDRS = parser_yacc.h unit_test.h base_cap_names.h
 GENERATED_HDRS = af_names.h generated_af_names.h \

parser/bignum.h

@@ -0,0 +1,235 @@
+/*
+ *   Copyright (c) 2023
+ *   Canonical Ltd. (All rights reserved)
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of version 2 of the GNU General Public
+ *   License published by the Free Software Foundation.
+ *
+ *   This program 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 General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, contact Novell, Inc. or Canonical
+ *   Ltd.
+ */
+
+#ifndef __AA_BIGNUM_H
+#define __AA_BIGNUM_H
+
+#include <iostream>
+#include <vector>
+#include <sstream>
+#include <algorithm>
+#include <string>
+
+class bignum
+{
+public:
+	std::vector<uint8_t> data;
+	uint64_t sad = 543;
+	uint8_t base;
+	bool negative = false;
+	bignum () {}
+
+	bignum (unsigned long val) {
+		if (val == 0)
+			data.push_back(val);
+		else {
+			while(val > 0) {
+				data.push_back(val % 10);
+				val /= 10;
+			}
+		}
+		base = 10;
+	}
+
+	bignum (const char *val) {
+		while (*val) {
+			data.push_back(*val - 48);
+			val++;
+		}
+		std::reverse(data.begin(), data.end());
+		base = 10;
+	}
+
+	bignum (const uint8_t val[16]) {
+		size_t i;
+		bool flag = true;
+		for (i = 0; i < 16; i++) {
+			if ((val[i] & 0xF0) >> 4 != 0)
+				flag = false;
+			if (!flag)
+				data.push_back((val[i] & 0xF0) >> 4);
+			if ((val[i] & 0x0F) != 0)
+				flag = false;
+			if (!flag)
+				data.push_back(val[i] & 0x0F);
+		}
+		std::reverse(data.begin(), data.end());
+		base = 16;
+	}
+
+	bignum operator+(const bignum &brhs) const {
+		bignum b1 = this->size() < brhs.size() ? *this : brhs;
+		bignum b2 = this->size() < brhs.size() ? brhs : *this;
+		bignum result;
+		result.base = this->base;
+		uint8_t carryover = 0;
+		uint8_t sum;
+		size_t i;
+		for (i = 0; i < b1.size(); i++) {
+			sum = b1[i] + b2[i] + carryover;
+			if (sum > base - 1)
+				carryover = 1;
+			else
+				carryover = 0;
+			result.data.push_back(sum % base);
+		}
+		for (; i < b2.size(); i++) {
+			sum = b2[i] + carryover;
+			if (sum > base - 1)
+				carryover = 1;
+			else
+				carryover = 0;
+			result.data.push_back(sum % base);
+		}
+		if (carryover != 0)
+			result.data.push_back(carryover);
+		return result;
+	}
+
+	bignum operator-(const bignum &brhs) const {
+		bignum b1 = this->size() < brhs.size() ? *this : brhs;
+		bignum b2 = this->size() < brhs.size() ? brhs : *this;
+		bignum result;
+		result.negative = *this < brhs;
+		result.base = this->base;
+		int8_t borrow = 0;
+		int8_t sub;
+		size_t i;
+		for (i = 0; i < b1.size(); i++) {
+			sub = b2[i] - b1[i] - borrow;
+			if (sub < 0) {
+				sub += base;
+				borrow = 1;
+			} else
+				borrow = 0;
+			result.data.push_back(sub);
+		}
+		for (; i < b2.size(); i++) {
+			sub = b2[i] - borrow;
+			if (sub < 0) {
+				sub += base;
+				borrow = 1;
+			} else
+				borrow = 0;
+			result.data.push_back(sub);
+		}
+		if (borrow) {
+			int8_t tmp = result.data[result.size() - 1] -= base;
+			tmp *= -1;
+			result.data[result.size() - 1] = tmp;
+		}
+		while (result.size() > 1 && result.data[result.size() - 1] == 0)
+			result.data.pop_back();
+
+		return result;
+	}
+	bool operator>=(const bignum &rhs) const {
+		return cmp_bignum(this->data, rhs.data) >= 0;
+	}
+	bool operator<=(const bignum &rhs) const {
+		return cmp_bignum(this->data, rhs.data) <= 0;
+	}
+	bool operator>(const bignum &rhs) const {
+		return cmp_bignum(this->data, rhs.data) > 0;
+	}
+	bool operator<(const bignum &rhs) const {
+		return cmp_bignum(this->data, rhs.data) < 0;
+	}
+	int operator[](int index) const {
+		return this->data[index];
+	}
+	friend std::ostream &operator<<(std::ostream &os, bignum &bn);
+	size_t size() const {
+		return data.size();
+	}
+
+	/*
+	  returns:
+	  - 0, if the lhs and rhs are equal;
+	  - a negative value if lhs is less than rhs;
+	  - a positive value if lhs is greater than rhs.
+	*/
+	int cmp_bignum(std::vector<uint8_t> lhs, std::vector<uint8_t> rhs) const
+	{
+		if (lhs.size() > rhs.size())
+			return 1;
+		else if (lhs.size() < rhs.size())
+			return -1;
+		else {
+			/* assumes the digits are stored in reverse order */
+			std::reverse(lhs.begin(), lhs.end());
+			std::reverse(rhs.begin(), rhs.end());
+			for (size_t i = 0; i < lhs.size(); i++) {
+				if (lhs[i] > rhs[i])
+					return 1;
+				if (lhs[i] < rhs[i])
+					return -1;
+			}
+		}
+		return 0;
+	}
+
+	static bignum lower_bound_regex(bignum val)
+	{
+		/* single digit numbers reduce to 0 */
+		if (val.size() == 1) {
+			val.data[0] = 0;
+			return val;
+		}
+
+		for (auto& j : val.data) {
+			uint8_t tmp = j;
+			j = 0;
+			if (tmp != val.base - 1) {
+				break;
+			}
+			if (&j == &val.data[val.size()-2]) {
+				val.data[val.size()-1] = 1;
+				break;
+			}
+		}
+		return val;
+
+	}
+
+	static bignum upper_bound_regex(bignum val)
+	{
+		for (auto& j : val.data) {
+			uint8_t tmp = j;
+			j = val.base - 1;
+			if (tmp != 0) {
+				break;
+			}
+		}
+		return val;
+	}
+
+};
+
+inline std::ostream &operator<<(std::ostream &os, bignum &bn)
+{
+	std::stringstream ss;
+	bignum tmp = bn;
+	std::reverse(tmp.data.begin(), tmp.data.end());
+	for (auto i : tmp.data)
+		ss << std::hex << (int) i;
+	os << ss.str();
+	return os;
+};
+
+#endif /* __AA_BIGNUM_H */

parser/parser.h

@@ -37,6 +37,7 @@
 #include "libapparmor_re/apparmor_re.h"
 #include "libapparmor_re/aare_rules.h"
 #include "rule.h"
+#include "bignum.h"
 
 #include <string>
 
@@ -411,6 +412,7 @@ extern pattern_t convert_aaregex_to_pcre(const char *aare, int anchor, int glob,
 extern int build_list_val_expr(std::string& buffer, struct value_list *list);
 extern int convert_entry(std::string& buffer, char *entry);
 extern int clear_and_convert_entry(std::string& buffer, char *entry);
+extern int convert_range(std::string& buffer, bignum start, bignum end);
 extern int process_regex(Profile *prof);
 extern int post_process_entry(struct cod_entry *entry);
 

parser/parser_regex.c

@@ -845,6 +845,98 @@ int clear_and_convert_entry(std::string& buffer, char *entry)
 	return convert_entry(buffer, entry);
 }
 
+static std::vector<std::pair<bignum, bignum>> regex_range_generator(bignum start, bignum end)
+{
+	std::vector<std::pair<bignum, bignum>> forward;
+	std::vector<std::pair<bignum, bignum>> reverse;
+	bignum next, prev;
+
+	while (start <= end) {
+		next = bignum::upper_bound_regex(start);
+		if (next > end)
+			break;
+
+		forward.emplace_back(start, next);
+		start = next + 1;
+	}
+
+	while (!end.negative && end >= start) {
+		prev = bignum::lower_bound_regex(end);
+		if (prev < start || prev.negative)
+			break;
+
+		reverse.emplace_back(prev, end);
+		end = prev - 1;
+	}
+
+	if (!end.negative && start <= end) {
+		forward.emplace_back(start, end);
+	}
+
+	forward.insert(forward.end(), reverse.rbegin(), reverse.rend());
+	return forward;
+}
+
+static std::string generate_regex_range(bignum start, bignum end)
+{
+	std::ostringstream result;
+	std::vector<std::pair<bignum, bignum>> regex_range;
+	int j;
+	regex_range = regex_range_generator(start, end);
+	for (auto &i: regex_range) {
+		bignum sstart = i.first;
+		bignum send = i.second;
+
+		for (j = sstart.size() - 1; j >= 0; j--) {
+			if (sstart[j] == send[j]) {
+				result << std::hex << sstart[j];
+			} else {
+				if (sstart[j] < 10 && send[j] >= 10) {
+					result << '[';
+					result << std::hex << sstart[j];
+					if (sstart[j] < 9) {
+						result << '-';
+						result << '9';
+					}
+					if (send[j] > 10) {
+						result << 'a';
+						result << '-';
+					}
+					result << std::hex << send[j];
+					result << ']';
+				} else {
+					result << '[';
+					result << std::hex << sstart[j];
+					result << '-';
+					result << std::hex << send[j];
+					result << ']';
+				}
+			}
+		}
+		if (&i != &regex_range.back())
+			result << ",";
+	}
+	return result.str();
+}
+
+int convert_range(std::string& buffer, bignum start, bignum end)
+{
+	pattern_t ptype;
+	int pos;
+
+	std::string regex_range = generate_regex_range(start, end);
+
+	if (!regex_range.empty()) {
+		ptype = convert_aaregex_to_pcre(regex_range.c_str(), 0, glob_default, buffer, &pos);
+		if (ptype == ePatternInvalid)
+			return FALSE;
+	} else {
+		buffer.append(default_match_pattern);
+	}
+
+	return TRUE;
+}
+
 int post_process_policydb_ents(Profile *prof)
 {
 	for (RuleList::iterator i = prof->rule_ents.begin(); i != prof->rule_ents.end(); i++) {