diff options
| -rw-r--r-- | rfc4251.C | 41 | ||||
| -rw-r--r-- | rfc4251.H | 116 | ||||
| -rw-r--r-- | rfc4251_gmp.C | 51 | ||||
| -rw-r--r-- | ssh-agent-filter.C | 14 |
4 files changed, 120 insertions, 102 deletions
@@ -1,10 +1,10 @@ /* * rfc4251.C -- support for name-list type from RFC 4251, section 5 * - * These are the conversions between an rfc4251::string containing a name-list - * and vector<string>. + * These are the conversions between an rfc4251::name_list and + * std::vector<std::string>. * - * Copyright (C) 2013,2015 Timo Weingärtner <timo@tiwe.de> + * Copyright (C) 2013,2015,2021 Timo Weingärtner <timo@tiwe.de> * * This file is part of ssh-agent-filter. * @@ -26,34 +26,33 @@ namespace rfc4251 { -string::string (std::vector<std::string> const & v) { +name_list::name_list (std::vector<std::string> const & v) { for (auto it = v.begin(); it != v.end();) { if (it->size() == 0) throw std::length_error{"name of zero length"}; - if (value.size() + it->size() > std::numeric_limits<uint32_t>::max()) - throw std::length_error{"32-bit limit for rfc4251::string exceeded"}; - value.insert(value.end(), it->data(), it->data() + it->size()); + check_length_against_limit(buf.size() + it->size()); + buf.insert(buf.end(), it->data(), it->data() + it->size()); ++it; if (it == v.end()) break; - value.push_back(','); + buf.push_back(','); } } -string::operator std::vector<std::string> () const { - std::vector<std::string> ret; - auto name_start = value.begin(); - if (name_start != value.end()) - for (auto it = name_start; ; ++it) { - if (it == value.end() or *it == ',') { - if (it == name_start) - throw std::length_error{"name of zero length"}; - ret.emplace_back(name_start, it); - name_start = it + 1; - } - if (it == value.end()) - break; +name_list::operator std::vector<std::string> () const { + std::vector<std::string> ret{}; + if (buf.empty()) return ret; + auto name_start = buf.begin(); + for (auto it = name_start; ; ++it) { + if (it == buf.end() or *it == ',') { + if (it == name_start) + throw std::length_error{"name of zero length"}; + ret.emplace_back(name_start, it); + name_start = it + 1; } + if (it == buf.end()) + break; + } return ret; } @@ -5,7 +5,9 @@ * rfc4251::boolean boolean * rfc4251::uint32 uint32 * rfc4251::uint64 uint64 - * rfc4251::string string, incl. mpint and name-list + * rfc4251::string string + * rfc4251::mpint mpint + * rfc4251::name_list name-list * * those structs contain the objects in their RFC 4251 representation, * conversions are provided via constructors and cast operators @@ -85,6 +87,48 @@ namespace internal { return os.write(x.buf.data(), x.buf.size()); } }; + + template<typename Length_Type> + struct variable_length : boost::totally_ordered<variable_length<Length_Type>> { + using length_type = Length_Type; + static_assert(std::is_unsigned_v<length_type>, "negative lengths are not supported"); + + std::vector<char> buf; + + variable_length () = default; + explicit variable_length (std::istream & is) { is >> *this; } + + size_t size () const noexcept { return buf.size(); } + char const * data () const noexcept { return buf.data(); } + char * data () noexcept { return buf.data(); } + + friend std::istream & operator>> (std::istream & is, variable_length & v) { + if (length_type const len{fixed_length<length_type>{is}}; is) { + v.buf.clear(); + v.buf.resize(len); + is.read(v.buf.data(), len); + } + return is; + } + friend std::ostream & operator<< (std::ostream & os, variable_length const & v) { + check_length_against_limit(v.buf.size()); + if (os << fixed_length<length_type>{static_cast<length_type>(v.buf.size())}) + os.write(v.buf.data(), v.buf.size()); + return os; + } + friend bool operator== (variable_length const & l, variable_length const & r) { + return l.buf == r.buf; + } + friend bool operator< (variable_length const & l, variable_length const & r) { + return l.buf < r.buf; + } + + constexpr static void check_length_against_limit(size_t const length) { + if (length > std::numeric_limits<length_type>::max()) + throw std::length_error{"numeric limit for length field in rfc4251::variable_length type exceeded"}; + } + + }; } using byte = internal::fixed_length<uint8_t>; @@ -92,59 +136,33 @@ using boolean = internal::fixed_length<bool>; using uint32 = internal::fixed_length<uint32_t>; using uint64 = internal::fixed_length<uint64_t>; -struct string : boost::totally_ordered<string> { - std::vector<char> value; - - string () = default; - inline explicit string (char const *, size_t); +struct string : internal::variable_length<uint32_t> { + using variable_length::variable_length; + + inline explicit string (char const * s, size_t l) { + check_length_against_limit(l); + buf.insert(buf.end(), s, s + l); + } explicit string (std::string const & s) : string{s.data(), s.size()} {} - explicit string (std::vector<std::string> const &); - explicit string (mpz_srcptr); - explicit string (mpz_class const & x) : string{x.get_mpz_t()} {} - inline explicit string (std::istream &); - size_t size () const noexcept { return value.size(); } - char const * data () const noexcept { return value.data(); } - char * data () noexcept { return value.data(); } + operator std::string () const { return {buf.cbegin(), buf.cend()}; } +}; - operator std::string () const { return {value.begin(), value.end()}; } +struct name_list : internal::variable_length<uint32_t> { + using variable_length::variable_length; + + explicit name_list (std::vector<std::string> const &); + operator std::vector<std::string> () const; - operator mpz_class () const; }; -inline string::string (char const * s, size_t l) { - if (l > std::numeric_limits<uint32_t>::max()) - throw std::length_error{"32-bit limit for rfc4251::string exceeded"}; - value.insert(value.end(), s, s + l); -} - -inline std::istream & operator>> (std::istream & is, string & s) { - s.value.clear(); - if (uint32_t const len{uint32{is}}; is) { - s.value.resize(len); - is.read(s.value.data(), len); - } - return is; -} - -inline std::ostream & operator<< (std::ostream & os, string const & s) { - if (s.value.size() > std::numeric_limits<uint32_t>::max()) - throw std::length_error{"32-bit limit for rfc4251::string exceeded"}; - if (os << uint32{static_cast<uint32_t>(s.value.size())}) - os.write(s.value.data(), s.value.size()); - return os; -} - -inline string::string (std::istream & is) { - is >> *this; -} - -inline bool operator== (string const & l, string const & r) { - return l.value == r.value; -} - -inline bool operator< (string const & l, string const & r) { - return l.value < r.value; -} +struct mpint : internal::variable_length<uint32_t> { + using variable_length::variable_length; + + explicit mpint (mpz_srcptr); + explicit mpint (mpz_class const & x) : mpint{x.get_mpz_t()} {} + + operator mpz_class () const; +}; } diff --git a/rfc4251_gmp.C b/rfc4251_gmp.C index b4c369b..06b6cf6 100644 --- a/rfc4251_gmp.C +++ b/rfc4251_gmp.C @@ -1,9 +1,9 @@ /* - * rfc4251_gmp.C -- implements mpint/gmp conversions for rfc4251::string + * rfc4251_gmp.C -- implements mpint/mpz conversions for rfc4251::mpint * * these functions need linking against libgmp * - * Copyright (C) 2013,2015 Timo Weingärtner <timo@tiwe.de> + * Copyright (C) 2013,2015,2021 Timo Weingärtner <timo@tiwe.de> * * This file is part of ssh-agent-filter. * @@ -25,36 +25,37 @@ namespace rfc4251 { -string::string (mpz_srcptr x) { - if (mpz_sgn(x) == 0) - return; - - auto const import_positive = [] (mpz_srcptr x, std::vector<char> & value) { +mpint::mpint (mpz_srcptr x) { + auto const import_positive = [] (mpz_srcptr x, std::vector<char> & buf) { size_t bits{mpz_sizeinbase(x, 2)}; size_t bytes{(bits + 7) / 8}; size_t extrabyte{(bits % 8) == 0}; // need extra byte if MSB is 1 to keep it non-negative - if (bytes + extrabyte > std::numeric_limits<uint32_t>::max()) - throw std::length_error{"32-bit limit for rfc4251::string exceeded"}; - value.resize(bytes + extrabyte); - value[0] = 0; - mpz_export(value.data() + extrabyte, nullptr, 1, 1, 1, 0, x); + check_length_against_limit(bytes + extrabyte); + buf.resize(bytes + extrabyte); + buf[0] = 0; + mpz_export(buf.data() + extrabyte, nullptr, 1, 1, 1, 0, x); }; - if (mpz_sgn(x) == 1) - import_positive(x, value); - else { - // handle two's complement: add 1, invert all bits - mpz_class tmp{x}; - tmp += 1; - import_positive(tmp.get_mpz_t(), value); - for (auto & i : value) - i ^= 0xff; + + switch (mpz_sgn(x)) { + case 0: + return; + case 1: + import_positive(x, buf); + return; + default: + // handle two's complement: add 1, invert all bits + mpz_class tmp{x}; + tmp += 1; + import_positive(tmp.get_mpz_t(), buf); + for (auto & i : buf) + i ^= 0xff; } } -string::operator mpz_class () const { - mpz_class ret; - mpz_import(ret.get_mpz_t(), value.size(), 1, 1, 1, 0, value.data()); - if (mpz_sizeinbase(ret.get_mpz_t(), 2) == value.size() * 8) { // negative +mpint::operator mpz_class () const { + mpz_class ret{}; + mpz_import(ret.get_mpz_t(), buf.size(), 1, 1, 1, 0, buf.data()); + if (mpz_sizeinbase(ret.get_mpz_t(), 2) == buf.size() * 8) { // negative mpz_com(ret.get_mpz_t(), ret.get_mpz_t()); ret += 1; mpz_neg(ret.get_mpz_t(), ret.get_mpz_t()); diff --git a/ssh-agent-filter.C b/ssh-agent-filter.C index 639e55c..c658b62 100644 --- a/ssh-agent-filter.C +++ b/ssh-agent-filter.C @@ -347,14 +347,14 @@ std::optional<string> dissect_auth_data_ssh_cert (rfc4251::string const & data) rfc4251::string nonce{datastream}; std::ostringstream key_to_be_signed{}; if (keytype_str == "ssh-rsa") { - rfc4251::string e{datastream}; - rfc4251::string n{datastream}; + rfc4251::mpint e{datastream}; + rfc4251::mpint n{datastream}; key_to_be_signed << rfc4251::string{keytype_str} << e << n; } else if (keytype_str == "ssh-dss") { - rfc4251::string p{datastream}; - rfc4251::string q{datastream}; - rfc4251::string g{datastream}; - rfc4251::string y{datastream}; + rfc4251::mpint p{datastream}; + rfc4251::mpint q{datastream}; + rfc4251::mpint g{datastream}; + rfc4251::mpint y{datastream}; key_to_be_signed << rfc4251::string{keytype_str} << p << q << g << y; } else if (keytype_str == "ecdsa-sha2-nistp256" || keytype_str == "ecdsa-sha2-nistp384" @@ -474,7 +474,7 @@ string describe_sign_request (rfc4251::string const & data_to_be_signed) { rfc4251::string handle_request (rfc4251::string const & r) { io::stream<io::array_source> request{r.data(), r.size()}; rfc4251::string ret; - io::stream<io::back_insert_device<vector<char>>> answer{ret.value}; + io::stream<io::back_insert_device<vector<char>>> answer{ret.buf}; arm(request); arm(answer); rfc4251::byte request_code{request}; |