diff options
Diffstat (limited to 'apt-pkg/contrib/gpgv.cc')
| -rw-r--r-- | apt-pkg/contrib/gpgv.cc | 568 |
1 files changed, 568 insertions, 0 deletions
diff --git a/apt-pkg/contrib/gpgv.cc b/apt-pkg/contrib/gpgv.cc new file mode 100644 index 0000000..2fa5b0c --- /dev/null +++ b/apt-pkg/contrib/gpgv.cc @@ -0,0 +1,568 @@ +// -*- mode: cpp; mode: fold -*- +// Include Files /*{{{*/ +#include <config.h> + +#include <apt-pkg/configuration.h> +#include <apt-pkg/error.h> +#include <apt-pkg/fileutl.h> +#include <apt-pkg/gpgv.h> +#include <apt-pkg/strutl.h> + +#include <cerrno> +#include <cstddef> +#include <cstdio> +#include <cstdlib> +#include <cstring> +#include <fcntl.h> +#include <sys/wait.h> +#include <unistd.h> + +#include <algorithm> +#include <fstream> +#include <iostream> +#include <memory> +#include <sstream> +#include <string> +#include <vector> + +#include <apti18n.h> + /*}}}*/ + +// syntactic sugar to wrap a raw pointer with a custom deleter in a std::unique_ptr +static std::unique_ptr<char, decltype(&free)> make_unique_char(void *const str = nullptr) +{ + return {static_cast<char *>(str), &free}; +} +static std::unique_ptr<FILE, decltype(&fclose)> make_unique_FILE(std::string const &filename, char const *const mode) +{ + return {fopen(filename.c_str(), mode), &fclose}; +} + +class LineBuffer /*{{{*/ +{ + char *buffer = nullptr; + size_t buffer_size = 0; + int line_length = 0; + // a "normal" find_last_not_of returns npos if not found + int find_last_not_of_length(APT::StringView const bad) const + { + for (int result = line_length - 1; result >= 0; --result) + if (bad.find(buffer[result]) == APT::StringView::npos) + return result + 1; + return 0; + } + + public: + bool empty() const noexcept { return view().empty(); } + APT::StringView view() const noexcept { return {buffer, static_cast<size_t>(line_length)}; } + bool starts_with(APT::StringView const start) const { return view().substr(0, start.size()) == start; } + + bool writeTo(FileFd *const to, size_t offset = 0) const + { + if (to == nullptr) + return true; + return to->Write(buffer + offset, line_length - offset); + } + bool writeLineTo(FileFd *const to) const + { + if (to == nullptr) + return true; + buffer[line_length] = '\n'; + bool const result = to->Write(buffer, line_length + 1); + buffer[line_length] = '\0'; + return result; + } + bool writeNewLineIf(FileFd *const to, bool const condition) const + { + if (not condition || to == nullptr) + return true; + return to->Write("\n", 1); + } + + bool readFrom(FILE *stream, std::string const &InFile, bool acceptEoF = false) + { + errno = 0; + line_length = getline(&buffer, &buffer_size, stream); + if (errno != 0) + return _error->Errno("getline", "Could not read from %s", InFile.c_str()); + if (line_length == -1) + { + if (acceptEoF) + return false; + return _error->Error("Splitting of clearsigned file %s failed as it doesn't contain all expected parts", InFile.c_str()); + } + // a) remove newline characters, so we can work consistently with lines + line_length = find_last_not_of_length("\n\r"); + // b) remove trailing whitespaces as defined by rfc4880 §7.1 + line_length = find_last_not_of_length(" \t"); + buffer[line_length] = '\0'; + return true; + } + + ~LineBuffer() { free(buffer); } +}; +static bool operator==(LineBuffer const &buf, APT::StringView const exp) noexcept +{ + return buf.view() == exp; +} +static bool operator!=(LineBuffer const &buf, APT::StringView const exp) noexcept +{ + return buf.view() != exp; +} + /*}}}*/ +// ExecGPGV - returns the command needed for verify /*{{{*/ +// --------------------------------------------------------------------- +/* Generating the commandline for calling gpg is somehow complicated as + we need to add multiple keyrings and user supplied options. + Also, as gpg has no options to enforce a certain reduced style of + clear-signed files (=the complete content of the file is signed and + the content isn't encoded) we do a divide and conquer approach here + and split up the clear-signed file in message and signature for gpg. + And as a cherry on the cake, we use our apt-key wrapper to do part + of the lifting in regards to merging keyrings. Fun for the whole family. +*/ +static void APT_PRINTF(4) apt_error(std::ostream &outterm, int const statusfd, int fd[2], const char *format, ...) +{ + std::ostringstream outstr; + std::ostream &out = (statusfd == -1) ? outterm : outstr; + va_list args; + ssize_t size = 400; + while (true) { + bool ret; + va_start(args,format); + ret = iovprintf(out, format, args, size); + va_end(args); + if (ret) + break; + } + if (statusfd != -1) + { + auto const errtag = "[APTKEY:] ERROR "; + outstr << '\n'; + auto const errtext = outstr.str(); + if (not FileFd::Write(fd[1], errtag, strlen(errtag)) || + not FileFd::Write(fd[1], errtext.data(), errtext.size())) + outterm << errtext << std::flush; + } +} +void ExecGPGV(std::string const &File, std::string const &FileGPG, + int const &statusfd, int fd[2], std::string const &key) +{ + #define EINTERNAL 111 + std::string const aptkey = _config->Find("Dir::Bin::apt-key", CMAKE_INSTALL_FULL_BINDIR "/apt-key"); + + bool const Debug = _config->FindB("Debug::Acquire::gpgv", false); + struct exiter { + std::vector<const char *> files; + void operator ()(int code) APT_NORETURN { + std::for_each(files.begin(), files.end(), unlink); + exit(code); + } + } local_exit; + + + std::vector<const char *> Args; + Args.reserve(10); + + Args.push_back(aptkey.c_str()); + Args.push_back("--quiet"); + Args.push_back("--readonly"); + auto const keysFileFpr = VectorizeString(key, ','); + for (auto const &k: keysFileFpr) + { + if (unlikely(k.empty())) + continue; + if (k[0] == '/') + { + Args.push_back("--keyring"); + Args.push_back(k.c_str()); + } + else + { + Args.push_back("--keyid"); + Args.push_back(k.c_str()); + } + } + Args.push_back("verify"); + + char statusfdstr[10]; + if (statusfd != -1) + { + Args.push_back("--status-fd"); + snprintf(statusfdstr, sizeof(statusfdstr), "%i", statusfd); + Args.push_back(statusfdstr); + } + + Configuration::Item const *Opts; + Opts = _config->Tree("Acquire::gpgv::Options"); + if (Opts != 0) + { + Opts = Opts->Child; + for (; Opts != 0; Opts = Opts->Next) + { + if (Opts->Value.empty()) + continue; + Args.push_back(Opts->Value.c_str()); + } + } + + enum { DETACHED, CLEARSIGNED } releaseSignature = (FileGPG != File) ? DETACHED : CLEARSIGNED; + auto sig = make_unique_char(); + auto data = make_unique_char(); + auto conf = make_unique_char(); + + // Dump the configuration so apt-key picks up the correct Dir values + { + { + std::string tmpfile; + strprintf(tmpfile, "%s/apt.conf.XXXXXX", GetTempDir().c_str()); + conf.reset(strdup(tmpfile.c_str())); + } + if (conf == nullptr) { + apt_error(std::cerr, statusfd, fd, "Couldn't create tempfile names for passing config to apt-key"); + local_exit(EINTERNAL); + } + int confFd = mkstemp(conf.get()); + if (confFd == -1) { + apt_error(std::cerr, statusfd, fd, "Couldn't create temporary file %s for passing config to apt-key", conf.get()); + local_exit(EINTERNAL); + } + local_exit.files.push_back(conf.get()); + + std::ofstream confStream(conf.get()); + close(confFd); + _config->Dump(confStream); + confStream.close(); + setenv("APT_CONFIG", conf.get(), 1); + } + + // Tell apt-key not to emit warnings + setenv("APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE", "1", 1); + + if (releaseSignature == DETACHED) + { + auto detached = make_unique_FILE(FileGPG, "r"); + if (detached.get() == nullptr) + { + apt_error(std::cerr, statusfd, fd, "Detached signature file '%s' could not be opened", FileGPG.c_str()); + local_exit(EINTERNAL); + } + LineBuffer buf; + bool open_signature = false; + bool found_badcontent = false; + size_t found_signatures = 0; + while (buf.readFrom(detached.get(), FileGPG, true)) + { + if (open_signature) + { + if (buf == "-----END PGP SIGNATURE-----") + open_signature = false; + else if (buf.starts_with("-")) + { + // the used Radix-64 is not using dash for any value, so a valid line can't + // start with one. Header keys could, but no existent one does and seems unlikely. + // Instead it smells a lot like a header the parser didn't recognize. + apt_error(std::cerr, statusfd, fd, "Detached signature file '%s' contains unexpected line starting with a dash", FileGPG.c_str()); + local_exit(112); + } + } + else //if (not open_signature) + { + if (buf == "-----BEGIN PGP SIGNATURE-----") + { + open_signature = true; + ++found_signatures; + if (found_badcontent) + break; + } + else + { + found_badcontent = true; + if (found_signatures != 0) + break; + } + } + } + if (found_signatures == 0 && statusfd != -1) + { + auto const errtag = "[GNUPG:] NODATA\n"; + FileFd::Write(fd[1], errtag, strlen(errtag)); + // guess if this is a binary signature, we never officially supported them, + // but silently accepted them via passing them unchecked to gpgv + if (found_badcontent) + { + rewind(detached.get()); + auto ptag = fgetc(detached.get()); + // §4.2 says that the first bit is always set and gpg seems to generate + // only old format which is indicated by the second bit not set + if (ptag != EOF && (ptag & 0x80) != 0 && (ptag & 0x40) == 0) + { + apt_error(std::cerr, statusfd, fd, "Detached signature file '%s' is in unsupported binary format", FileGPG.c_str()); + local_exit(112); + } + } + // This is not an attack attempt but a file even gpgv would complain about + // likely the result of a paywall which is covered by the gpgv method + local_exit(113); + } + else if (found_badcontent) + { + apt_error(std::cerr, statusfd, fd, "Detached signature file '%s' contains lines not belonging to a signature", FileGPG.c_str()); + local_exit(112); + } + if (open_signature) + { + apt_error(std::cerr, statusfd, fd, "Detached signature file '%s' contains unclosed signatures", FileGPG.c_str()); + local_exit(112); + } + + Args.push_back(FileGPG.c_str()); + Args.push_back(File.c_str()); + } + else // clear-signed file + { + FileFd signature; + if (GetTempFile("apt.sig", false, &signature) == nullptr) + local_exit(EINTERNAL); + sig.reset(strdup(signature.Name().c_str())); + local_exit.files.push_back(sig.get()); + FileFd message; + if (GetTempFile("apt.data", false, &message) == nullptr) + local_exit(EINTERNAL); + data.reset(strdup(message.Name().c_str())); + local_exit.files.push_back(data.get()); + + if (signature.Failed() || message.Failed() || + not SplitClearSignedFile(File, &message, nullptr, &signature)) + { + apt_error(std::cerr, statusfd, fd, "Splitting up %s into data and signature failed", File.c_str()); + local_exit(112); + } + Args.push_back(sig.get()); + Args.push_back(data.get()); + } + + Args.push_back(NULL); + + if (Debug) + { + std::clog << "Preparing to exec: "; + for (std::vector<const char *>::const_iterator a = Args.begin(); *a != NULL; ++a) + std::clog << " " << *a; + std::clog << std::endl; + } + + if (statusfd != -1) + { + int const nullfd = open("/dev/null", O_WRONLY); + close(fd[0]); + // Redirect output to /dev/null; we read from the status fd + if (statusfd != STDOUT_FILENO) + dup2(nullfd, STDOUT_FILENO); + if (statusfd != STDERR_FILENO) + dup2(nullfd, STDERR_FILENO); + // Redirect the pipe to the status fd (3) + dup2(fd[1], statusfd); + + putenv((char *)"LANG="); + putenv((char *)"LC_ALL="); + putenv((char *)"LC_MESSAGES="); + } + + + // We have created tempfiles we have to clean up + // and we do an additional check, so fork yet another time … + pid_t pid = ExecFork(); + if(pid < 0) { + apt_error(std::cerr, statusfd, fd, "Fork failed for %s to check %s", Args[0], File.c_str()); + local_exit(EINTERNAL); + } + if(pid == 0) + { + if (statusfd != -1) + dup2(fd[1], statusfd); + execvp(Args[0], (char **) &Args[0]); + apt_error(std::cerr, statusfd, fd, "Couldn't execute %s to check %s", Args[0], File.c_str()); + local_exit(EINTERNAL); + } + + // Wait and collect the error code - taken from WaitPid as we need the exact Status + int Status; + while (waitpid(pid,&Status,0) != pid) + { + if (errno == EINTR) + continue; + apt_error(std::cerr, statusfd, fd, _("Waited for %s but it wasn't there"), "apt-key"); + local_exit(EINTERNAL); + } + + // check if it exit'ed normally … + if (not WIFEXITED(Status)) + { + apt_error(std::cerr, statusfd, fd, _("Sub-process %s exited unexpectedly"), "apt-key"); + local_exit(EINTERNAL); + } + + // … and with a good exit code + if (WEXITSTATUS(Status) != 0) + { + // we forward the statuscode, so don't generate a message on the fd in this case + apt_error(std::cerr, -1, fd, _("Sub-process %s returned an error code (%u)"), "apt-key", WEXITSTATUS(Status)); + local_exit(WEXITSTATUS(Status)); + } + + // everything fine + local_exit(0); +} + /*}}}*/ +// SplitClearSignedFile - split message into data/signature /*{{{*/ +bool SplitClearSignedFile(std::string const &InFile, FileFd * const ContentFile, + std::vector<std::string> * const ContentHeader, FileFd * const SignatureFile) +{ + auto in = make_unique_FILE(InFile, "r"); + if (in.get() == nullptr) + return _error->Errno("fopen", "can not open %s", InFile.c_str()); + + struct ScopedErrors + { + ScopedErrors() { _error->PushToStack(); } + ~ScopedErrors() { _error->MergeWithStack(); } + } scoped; + LineBuffer buf; + + // start of the message + if (not buf.readFrom(in.get(), InFile)) + return false; // empty or read error + if (buf != "-----BEGIN PGP SIGNED MESSAGE-----") + { + // this might be an unsigned file we don't want to report errors for, + // but still finish unsuccessful none the less. + while (buf.readFrom(in.get(), InFile, true)) + if (buf == "-----BEGIN PGP SIGNED MESSAGE-----") + return _error->Error("Clearsigned file '%s' does not start with a signed message block.", InFile.c_str()); + + return false; + } + + // save "Hash" Armor Headers + while (true) + { + if (not buf.readFrom(in.get(), InFile)) + return false; + if (buf.empty()) + break; // empty line ends the Armor Headers + if (buf.starts_with("-")) + // § 6.2 says unknown keys should be reported to the user. We don't go that far, + // but we assume that there will never be a header key starting with a dash + return _error->Error("Clearsigned file '%s' contains unexpected line starting with a dash (%s)", InFile.c_str(), "armor"); + if (ContentHeader != nullptr && buf.starts_with("Hash: ")) + ContentHeader->push_back(buf.view().to_string()); + } + + // the message itself + bool first_line = true; + while (true) + { + if (not buf.readFrom(in.get(), InFile)) + return false; + + if (buf.starts_with("-")) + { + if (buf == "-----BEGIN PGP SIGNATURE-----") + { + if (not buf.writeLineTo(SignatureFile)) + return false; + break; + } + else if (buf.starts_with("- ")) + { + // we don't have any fields which need to be dash-escaped, + // but implementations are free to escape all lines … + if (not buf.writeNewLineIf(ContentFile, not first_line) || not buf.writeTo(ContentFile, 2)) + return false; + } + else + // § 7.1 says a client should warn, but we don't really work with files which + // should contain lines starting with a dash, so it is a lot more likely that + // this is an attempt to trick our parser vs. gpgv parser into ignoring a header + return _error->Error("Clearsigned file '%s' contains unexpected line starting with a dash (%s)", InFile.c_str(), "msg"); + } + else if (not buf.writeNewLineIf(ContentFile, not first_line) || not buf.writeTo(ContentFile)) + return false; + first_line = false; + } + + // collect all signatures + bool open_signature = true; + while (true) + { + if (not buf.readFrom(in.get(), InFile, true)) + break; + + if (open_signature) + { + if (buf == "-----END PGP SIGNATURE-----") + open_signature = false; + else if (buf.starts_with("-")) + // the used Radix-64 is not using dash for any value, so a valid line can't + // start with one. Header keys could, but no existent one does and seems unlikely. + // Instead it smells a lot like a header the parser didn't recognize. + return _error->Error("Clearsigned file '%s' contains unexpected line starting with a dash (%s)", InFile.c_str(), "sig"); + } + else //if (not open_signature) + { + if (buf == "-----BEGIN PGP SIGNATURE-----") + open_signature = true; + else + return _error->Error("Clearsigned file '%s' contains unsigned lines.", InFile.c_str()); + } + + if (not buf.writeLineTo(SignatureFile)) + return false; + } + if (open_signature) + return _error->Error("Signature in file %s wasn't closed", InFile.c_str()); + + // Flush the files + if (SignatureFile != nullptr) + SignatureFile->Flush(); + if (ContentFile != nullptr) + ContentFile->Flush(); + + // Catch-all for "unhandled" read/sync errors + if (_error->PendingError()) + return false; + return true; +} + /*}}}*/ +bool OpenMaybeClearSignedFile(std::string const &ClearSignedFileName, FileFd &MessageFile) /*{{{*/ +{ + // Buffered file + if (GetTempFile("clearsigned.message", true, &MessageFile, true) == nullptr) + return false; + if (MessageFile.Failed()) + return _error->Error("Couldn't open temporary file to work with %s", ClearSignedFileName.c_str()); + + _error->PushToStack(); + bool const splitDone = SplitClearSignedFile(ClearSignedFileName, &MessageFile, NULL, NULL); + bool const errorDone = _error->PendingError(); + _error->MergeWithStack(); + if (not splitDone) + { + MessageFile.Close(); + + if (errorDone) + return false; + + // we deal with an unsigned file + MessageFile.Open(ClearSignedFileName, FileFd::ReadOnly); + } + else // clear-signed + { + if (not MessageFile.Seek(0)) + return _error->Errno("lseek", "Unable to seek back in message for file %s", ClearSignedFileName.c_str()); + } + + return not MessageFile.Failed(); +} + /*}}}*/ |