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-rw-r--r--apt-pkg/contrib/gpgv.cc568
1 files changed, 568 insertions, 0 deletions
diff --git a/apt-pkg/contrib/gpgv.cc b/apt-pkg/contrib/gpgv.cc
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+++ b/apt-pkg/contrib/gpgv.cc
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+// -*- 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();
+}
+ /*}}}*/