#include <config.h> #include "aptmethod.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 <ctype.h> #include <errno.h> #include <stddef.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/wait.h> #include <unistd.h> #include <algorithm> #include <array> #include <iostream> #include <iterator> #include <sstream> #include <string> #include <vector> #include <apti18n.h> using std::string; using std::vector; #define GNUPGPREFIX "[GNUPG:]" #define GNUPGBADSIG "[GNUPG:] BADSIG" #define GNUPGERRSIG "[GNUPG:] ERRSIG" #define GNUPGNOPUBKEY "[GNUPG:] NO_PUBKEY" #define GNUPGVALIDSIG "[GNUPG:] VALIDSIG" #define GNUPGGOODSIG "[GNUPG:] GOODSIG" #define GNUPGEXPKEYSIG "[GNUPG:] EXPKEYSIG" #define GNUPGEXPSIG "[GNUPG:] EXPSIG" #define GNUPGREVKEYSIG "[GNUPG:] REVKEYSIG" #define GNUPGNODATA "[GNUPG:] NODATA" #define APTKEYWARNING "[APTKEY:] WARNING" #define APTKEYERROR "[APTKEY:] ERROR" struct Digest { enum class State { Untrusted, Weak, Trusted, } state; char name[32]; State getState() const { std::string optionUntrusted; std::string optionWeak; strprintf(optionUntrusted, "APT::Hashes::%s::Untrusted", name); strprintf(optionWeak, "APT::Hashes::%s::Weak", name); if (_config->FindB(optionUntrusted, false) == true) return State::Untrusted; if (_config->FindB(optionWeak, false) == true) return State::Weak; return state; } }; static constexpr Digest Digests[] = { {Digest::State::Untrusted, "Invalid digest"}, {Digest::State::Untrusted, "MD5"}, {Digest::State::Untrusted, "SHA1"}, {Digest::State::Untrusted, "RIPE-MD/160"}, {Digest::State::Trusted, "Reserved digest"}, {Digest::State::Trusted, "Reserved digest"}, {Digest::State::Trusted, "Reserved digest"}, {Digest::State::Trusted, "Reserved digest"}, {Digest::State::Trusted, "SHA256"}, {Digest::State::Trusted, "SHA384"}, {Digest::State::Trusted, "SHA512"}, {Digest::State::Trusted, "SHA224"}, }; static Digest FindDigest(std::string const & Digest) { int id = atoi(Digest.c_str()); if (id >= 0 && static_cast<unsigned>(id) < _count(Digests)) { return Digests[id]; } else { return Digests[0]; } } struct Signer { std::string key; std::string note; }; static bool IsTheSameKey(std::string const &validsig, std::string const &goodsig) { // VALIDSIG reports a fingerprint (40 = 24 + 16), GOODSIG can be longid (16) or // fingerprint according to documentation in DETAILS.gz if (goodsig.length() == 40 + strlen("GOODSIG ")) return validsig.compare(0, 40, goodsig, strlen("GOODSIG "), 40) == 0; return validsig.compare(24, 16, goodsig, strlen("GOODSIG "), 16) == 0; } class GPGVMethod : public aptMethod { private: string VerifyGetSigners(const char *file, const char *outfile, std::string const &key, vector<string> &GoodSigners, vector<string> &BadSigners, vector<string> &WorthlessSigners, vector<Signer> &SoonWorthlessSigners, vector<string> &NoPubKeySigners); protected: virtual bool URIAcquire(std::string const &Message, FetchItem *Itm) APT_OVERRIDE; public: GPGVMethod() : aptMethod("gpgv","1.0",SingleInstance | SendConfig) {}; }; static void PushEntryWithKeyID(std::vector<std::string> &Signers, char * const buffer, bool const Debug) { char * const msg = buffer + sizeof(GNUPGPREFIX); char *p = msg; // skip the message while (*p && !isspace(*p)) ++p; // skip the separator whitespace ++p; // skip the hexdigit fingerprint while (*p && isxdigit(*p)) ++p; // cut the rest from the message *p = '\0'; if (Debug == true) std::clog << "Got " << msg << " !" << std::endl; Signers.push_back(msg); } static void PushEntryWithUID(std::vector<std::string> &Signers, char * const buffer, bool const Debug) { std::string msg = buffer + sizeof(GNUPGPREFIX); auto const nuke = msg.find_last_not_of("\n\t\r"); if (nuke != std::string::npos) msg.erase(nuke + 1); if (Debug == true) std::clog << "Got " << msg << " !" << std::endl; Signers.push_back(msg); } string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile, std::string const &key, vector<string> &GoodSigners, vector<string> &BadSigners, vector<string> &WorthlessSigners, vector<Signer> &SoonWorthlessSigners, vector<string> &NoPubKeySigners) { bool const Debug = DebugEnabled(); if (Debug == true) std::clog << "inside VerifyGetSigners" << std::endl; int fd[2]; bool const keyIsID = (key.empty() == false && key[0] != '/'); if (pipe(fd) < 0) return "Couldn't create pipe"; pid_t pid = fork(); if (pid < 0) return string("Couldn't spawn new process") + strerror(errno); else if (pid == 0) ExecGPGV(outfile, file, 3, fd, (keyIsID ? "" : key)); close(fd[1]); FILE *pipein = fdopen(fd[0], "r"); // Loop over the output of apt-key (which really is gnupg), and check the signatures. std::vector<std::string> ValidSigners; std::vector<std::string> ErrSigners; size_t buffersize = 0; char *buffer = NULL; bool gotNODATA = false; while (1) { if (getline(&buffer, &buffersize, pipein) == -1) break; if (Debug == true) std::clog << "Read: " << buffer << std::endl; // Push the data into three separate vectors, which // we later concatenate. They're kept separate so // if we improve the apt method communication stuff later // it will be better. if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0) PushEntryWithUID(BadSigners, buffer, Debug); else if (strncmp(buffer, GNUPGERRSIG, sizeof(GNUPGERRSIG)-1) == 0) PushEntryWithKeyID(ErrSigners, buffer, Debug); else if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0) { PushEntryWithKeyID(NoPubKeySigners, buffer, Debug); ErrSigners.erase(std::remove_if(ErrSigners.begin(), ErrSigners.end(), [&](std::string const &errsig) { return errsig.compare(strlen("ERRSIG "), 16, buffer, sizeof(GNUPGNOPUBKEY), 16) == 0; }), ErrSigners.end()); } else if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGNODATA)-1) == 0) gotNODATA = true; else if (strncmp(buffer, GNUPGEXPKEYSIG, sizeof(GNUPGEXPKEYSIG)-1) == 0) PushEntryWithUID(WorthlessSigners, buffer, Debug); else if (strncmp(buffer, GNUPGEXPSIG, sizeof(GNUPGEXPSIG)-1) == 0) PushEntryWithUID(WorthlessSigners, buffer, Debug); else if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0) PushEntryWithUID(WorthlessSigners, buffer, Debug); else if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0) PushEntryWithKeyID(GoodSigners, buffer, Debug); else if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0) { std::istringstream iss(buffer + sizeof(GNUPGVALIDSIG)); vector<string> tokens{std::istream_iterator<string>{iss}, std::istream_iterator<string>{}}; auto const sig = tokens[0]; // Reject weak digest algorithms Digest digest = FindDigest(tokens[7]); switch (digest.getState()) { case Digest::State::Weak: // Treat them like an expired key: For that a message about expiry // is emitted, a VALIDSIG, but no GOODSIG. SoonWorthlessSigners.push_back({sig, digest.name}); if (Debug == true) std::clog << "Got weak VALIDSIG, key ID: " << sig << std::endl; break; case Digest::State::Untrusted: // Treat them like an expired key: For that a message about expiry // is emitted, a VALIDSIG, but no GOODSIG. WorthlessSigners.push_back(sig); GoodSigners.erase(std::remove_if(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &goodsig) { return IsTheSameKey(sig, goodsig); }), GoodSigners.end()); if (Debug == true) std::clog << "Got untrusted VALIDSIG, key ID: " << sig << std::endl; break; case Digest::State::Trusted: if (Debug == true) std::clog << "Got trusted VALIDSIG, key ID: " << sig << std::endl; break; } ValidSigners.push_back(sig); } else if (strncmp(buffer, APTKEYWARNING, sizeof(APTKEYWARNING)-1) == 0) Warning("%s", buffer + sizeof(APTKEYWARNING)); else if (strncmp(buffer, APTKEYERROR, sizeof(APTKEYERROR)-1) == 0) _error->Error("%s", buffer + sizeof(APTKEYERROR)); } fclose(pipein); free(buffer); std::move(ErrSigners.begin(), ErrSigners.end(), std::back_inserter(WorthlessSigners)); // apt-key has a --keyid parameter, but this requires gpg, so we call it without it // and instead check after the fact which keyids where used for verification if (keyIsID == true) { if (Debug == true) std::clog << "GoodSigs needs to be limited to keyid(s) " << key << std::endl; auto const limitedTo = VectorizeString(key, ','); std::vector<std::string> filteredGood; for (auto &&good: GoodSigners) { if (Debug == true) std::clog << "Key " << good << " is good sig, is it also a valid and allowed one? "; bool found = false; for (auto const &l : limitedTo) { if (IsTheSameKey(l, good) == false) continue; // GOODSIG might be "just" a longid, so we check VALIDSIG which is always a fingerprint if (std::find(ValidSigners.begin(), ValidSigners.end(), l) == ValidSigners.end()) continue; found = true; break; } if (Debug) std::clog << (found ? "yes" : "no") << "\n"; if (found) filteredGood.emplace_back(std::move(good)); else NoPubKeySigners.emplace_back(std::move(good)); } GoodSigners = std::move(filteredGood); } int status; waitpid(pid, &status, 0); if (Debug == true) { ioprintf(std::clog, "gpgv exited with status %i\n", WEXITSTATUS(status)); } if (Debug) { std::cerr << "Summary:" << std::endl << " Good: "; std::copy(GoodSigners.begin(), GoodSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", ")); std::cerr << std::endl << " Bad: "; std::copy(BadSigners.begin(), BadSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", ")); std::cerr << std::endl << " Worthless: "; std::copy(WorthlessSigners.begin(), WorthlessSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", ")); std::cerr << std::endl << " SoonWorthless: "; std::for_each(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [](Signer const &sig) { std::cerr << sig.key << ", "; }); std::cerr << std::endl << " NoPubKey: "; std::copy(NoPubKeySigners.begin(), NoPubKeySigners.end(), std::ostream_iterator<std::string>(std::cerr, ", ")); std::cerr << std::endl << " NODATA: " << (gotNODATA ? "yes" : "no") << std::endl; } if (WEXITSTATUS(status) == 112) { // acquire system checks for "NODATA" to generate GPG errors (the others are only warnings) std::string errmsg; //TRANSLATORS: %s is a single techy word like 'NODATA' strprintf(errmsg, _("Clearsigned file isn't valid, got '%s' (does the network require authentication?)"), "NODATA"); return errmsg; } else if (gotNODATA) { // acquire system checks for "NODATA" to generate GPG errors (the others are only warnings) std::string errmsg; //TRANSLATORS: %s is a single techy word like 'NODATA' strprintf(errmsg, _("Signed file isn't valid, got '%s' (does the network require authentication?)"), "NODATA"); return errmsg; } else if (WEXITSTATUS(status) == 0) { if (keyIsID) { // gpgv will report success, but we want to enforce a certain keyring // so if we haven't found the key the valid we found is in fact invalid if (GoodSigners.empty()) return _("At least one invalid signature was encountered."); } else { if (GoodSigners.empty()) return _("Internal error: Good signature, but could not determine key fingerprint?!"); } return ""; } else if (WEXITSTATUS(status) == 1) return _("At least one invalid signature was encountered."); else if (WEXITSTATUS(status) == 111) return _("Could not execute 'apt-key' to verify signature (is gnupg installed?)"); else return _("Unknown error executing apt-key"); } bool GPGVMethod::URIAcquire(std::string const &Message, FetchItem *Itm) { URI const Get = Itm->Uri; string const Path = Get.Host + Get.Path; // To account for relative paths std::string const key = LookupTag(Message, "Signed-By"); vector<string> GoodSigners; vector<string> BadSigners; // a worthless signature is a expired or revoked one vector<string> WorthlessSigners; vector<Signer> SoonWorthlessSigners; vector<string> NoPubKeySigners; FetchResult Res; Res.Filename = Itm->DestFile; URIStart(Res); // Run apt-key on file, extract contents and get the key ID of the signer string const msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(), key, GoodSigners, BadSigners, WorthlessSigners, SoonWorthlessSigners, NoPubKeySigners); if (_error->PendingError()) return false; // Check if all good signers are soon worthless and warn in that case if (std::all_of(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &good) { return std::any_of(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [&](Signer const &weak) { return IsTheSameKey(weak.key, good); }); })) { for (auto const & Signer : SoonWorthlessSigners) // TRANSLATORS: The second %s is the reason and is untranslated for repository owners. Warning(_("Signature by key %s uses weak digest algorithm (%s)"), Signer.key.c_str(), Signer.note.c_str()); } if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty()) { string errmsg; // In this case, something bad probably happened, so we just go // with what the other method gave us for an error message. if (BadSigners.empty() && WorthlessSigners.empty() && NoPubKeySigners.empty()) errmsg = msg; else { if (!BadSigners.empty()) { errmsg += _("The following signatures were invalid:\n"); for (vector<string>::iterator I = BadSigners.begin(); I != BadSigners.end(); ++I) errmsg += (*I + "\n"); } if (!WorthlessSigners.empty()) { errmsg += _("The following signatures were invalid:\n"); for (vector<string>::iterator I = WorthlessSigners.begin(); I != WorthlessSigners.end(); ++I) errmsg += (*I + "\n"); } if (!NoPubKeySigners.empty()) { errmsg += _("The following signatures couldn't be verified because the public key is not available:\n"); for (vector<string>::iterator I = NoPubKeySigners.begin(); I != NoPubKeySigners.end(); ++I) errmsg += (*I + "\n"); } } // this is only fatal if we have no good sigs or if we have at // least one bad signature. good signatures and NoPubKey signatures // happen easily when a file is signed with multiple signatures if(GoodSigners.empty() or !BadSigners.empty()) return _error->Error("%s", errmsg.c_str()); } // Just pass the raw output up, because passing it as a real data // structure is too difficult with the method stuff. We keep it // as three separate vectors for future extensibility. Res.GPGVOutput = GoodSigners; std::move(BadSigners.begin(), BadSigners.end(), std::back_inserter(Res.GPGVOutput)); std::move(NoPubKeySigners.begin(), NoPubKeySigners.end(), std::back_inserter(Res.GPGVOutput)); URIDone(Res); if (DebugEnabled()) std::clog << "apt-key succeeded\n"; return true; } int main() { return GPGVMethod().Run(); }