Make the weak signature message less ambigious

[apt.git] / methods / gpgv.cc

diff --git a/methods/gpgv.cc b/methods/gpgv.cc
index 7e8500c51b865f74bf230bc9881582f653ee2d8a..70207e6150ff52061ed47e9e23a021aaa8ab83e8 100644 (file)
--- a/methods/gpgv.cc
+++ b/methods/gpgv.cc
@@ -6,6 +6,7 @@
 #include <apt-pkg/gpgv.h>
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/gpgv.h>
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/fileutl.h>

+#include "aptmethod.h"

 
 #include <ctype.h>
 #include <errno.h>
 
 #include <ctype.h>
 #include <errno.h>


@@ -15,6 +16,11 @@
 #include <string.h>
 #include <sys/wait.h>
 #include <unistd.h>
 #include <string.h>
 #include <sys/wait.h>
 #include <unistd.h>

+
+#include <array>
+#include <algorithm>
+#include <sstream>
+#include <iterator>

 #include <iostream>
 #include <string>
 #include <vector>
 #include <iostream>
 #include <string>
 #include <vector>


@@ -33,27 +39,68 @@ using std::vector;
 #define GNUPGREVKEYSIG "[GNUPG:] REVKEYSIG"
 #define GNUPGNODATA "[GNUPG:] NODATA"
 
 #define GNUPGREVKEYSIG "[GNUPG:] REVKEYSIG"
 #define GNUPGNODATA "[GNUPG:] NODATA"
 

-class GPGVMethod : public pkgAcqMethod
+struct Digest {
+   enum class State {
+      Untrusted,
+      Weak,
+      Trusted,
+   } state;
+   char name[32];
+};
+
+static constexpr Digest Digests[] = {
+   {Digest::State::Untrusted, "Invalid digest"},
+   {Digest::State::Untrusted, "MD5"},
+   {Digest::State::Weak, "SHA1"},
+   {Digest::State::Weak, "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;
+};
+
+class GPGVMethod : public aptMethod

 {
    private:
    string VerifyGetSigners(const char *file, const char *outfile,
 {
    private:
    string VerifyGetSigners(const char *file, const char *outfile,

-                               vector<string> &GoodSigners, 
+                               std::string const &key,
+                               vector<string> &GoodSigners,

                                 vector<string> &BadSigners,
                                 vector<string> &WorthlessSigners,
                                 vector<string> &BadSigners,
                                 vector<string> &WorthlessSigners,

+                                vector<Signer> &SoonWorthlessSigners,

                                vector<string> &NoPubKeySigners);
                                vector<string> &NoPubKeySigners);

-   

    protected:
    protected:

-   virtual bool Fetch(FetchItem *Itm);
-   
+   virtual bool URIAcquire(std::string const &Message, FetchItem *Itm) APT_OVERRIDE;

    public:
    
    public:
    

-   GPGVMethod() : pkgAcqMethod("1.0",SingleInstance | SendConfig) {};
+   GPGVMethod() : aptMethod("gpgv","1.0",SingleInstance | SendConfig) {};

 };
 
 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
 };
 
 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,

+                                        std::string const &key,

                                         vector<string> &GoodSigners,
                                         vector<string> &BadSigners,
                                         vector<string> &WorthlessSigners,
                                         vector<string> &GoodSigners,
                                         vector<string> &BadSigners,
                                         vector<string> &WorthlessSigners,

+                                        vector<Signer> &SoonWorthlessSigners,

                                         vector<string> &NoPubKeySigners)
 {
    bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);
                                         vector<string> &NoPubKeySigners)
 {
    bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);


@@ -62,6 +109,7 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
       std::clog << "inside VerifyGetSigners" << std::endl;
 
    int fd[2];
       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";
 
    if (pipe(fd) < 0)
       return "Couldn't create pipe";


@@ -70,39 +118,19 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
    if (pid < 0)
       return string("Couldn't spawn new process") + strerror(errno);
    else if (pid == 0)
    if (pid < 0)
       return string("Couldn't spawn new process") + strerror(errno);
    else if (pid == 0)

-      ExecGPGV(outfile, file, 3, fd);
+      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.
    close(fd[1]);
 
    FILE *pipein = fdopen(fd[0], "r");
 
    // Loop over the output of apt-key (which really is gnupg), and check the signatures.

-   size_t buffersize = 64;
-   char *buffer = (char *) malloc(buffersize);
-   size_t bufferoff = 0;
+   std::vector<std::string> ValidSigners;
+   size_t buffersize = 0;
+   char *buffer = NULL;

    while (1)
    {
    while (1)
    {

-      int c;
-
-      // Read a line.  Sigh.
-      while ((c = getc(pipein)) != EOF && c != '\n')
-      {
-        if (bufferoff == buffersize)
-        {
-           char* newBuffer = (char *) realloc(buffer, buffersize *= 2);
-           if (newBuffer == NULL)
-           {
-              free(buffer);
-              return "Couldn't allocate a buffer big enough for reading";
-           }
-           buffer = newBuffer;
-        }
-         *(buffer+bufferoff) = c;
-         bufferoff++;
-      }
-      if (bufferoff == 0 && c == EOF)
-         break;
-      *(buffer+bufferoff) = '\0';
-      bufferoff = 0;
+      if (getline(&buffer, &buffersize, pipein) == -1)
+        break;

       if (Debug == true)
          std::clog << "Read: " << buffer << std::endl;
 
       if (Debug == true)
          std::clog << "Read: " << buffer << std::endl;
 


@@ -116,32 +144,31 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
             std::clog << "Got BADSIG! " << std::endl;
          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }
             std::clog << "Got BADSIG! " << std::endl;
          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }

-      
-      if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
+      else if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)

       {
          if (Debug == true)
             std::clog << "Got NO_PUBKEY " << std::endl;
          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }
       {
          if (Debug == true)
             std::clog << "Got NO_PUBKEY " << std::endl;
          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }

-      if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
+      else if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)

       {
          if (Debug == true)
             std::clog << "Got NODATA! " << std::endl;
          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }
       {
          if (Debug == true)
             std::clog << "Got NODATA! " << std::endl;
          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }

-      if (strncmp(buffer, GNUPGKEYEXPIRED, sizeof(GNUPGKEYEXPIRED)-1) == 0)
+      else if (strncmp(buffer, GNUPGKEYEXPIRED, sizeof(GNUPGKEYEXPIRED)-1) == 0)

       {
          if (Debug == true)
             std::clog << "Got KEYEXPIRED! " << std::endl;
          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }
       {
          if (Debug == true)
             std::clog << "Got KEYEXPIRED! " << std::endl;
          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }

-      if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0)
+      else if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0)

       {
          if (Debug == true)
             std::clog << "Got REVKEYSIG! " << std::endl;
          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }
       {
          if (Debug == true)
             std::clog << "Got REVKEYSIG! " << std::endl;
          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
       }

-      if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0)
+      else if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0)

       {
          char *sig = buffer + sizeof(GNUPGPREFIX);
          char *p = sig + sizeof("GOODSIG");
       {
          char *sig = buffer + sizeof(GNUPGPREFIX);
          char *p = sig + sizeof("GOODSIG");


@@ -152,10 +179,69 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
             std::clog << "Got GOODSIG, key ID:" << sig << std::endl;
          GoodSigners.push_back(string(sig));
       }
             std::clog << "Got GOODSIG, key ID:" << sig << std::endl;
          GoodSigners.push_back(string(sig));
       }

+      else if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
+      {
+         char *sig = buffer + sizeof(GNUPGVALIDSIG);
+         std::istringstream iss((string(sig)));
+         vector<string> tokens{std::istream_iterator<string>{iss},
+                               std::istream_iterator<string>{}};
+         char *p = sig;
+         while (*p && isxdigit(*p))
+            p++;
+         *p = 0;
+         if (Debug == true)
+            std::clog << "Got VALIDSIG, key ID: " << sig << std::endl;
+         // Reject weak digest algorithms
+         Digest digest = FindDigest(tokens[7]);
+         switch (digest.state) {
+         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({string(sig), digest.name});
+            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(string(sig));
+            GoodSigners.erase(std::remove(GoodSigners.begin(), GoodSigners.end(), string(sig)));
+            break;
+         case Digest::State::Trusted:
+            break;
+         }
+
+         ValidSigners.push_back(string(sig));
+      }

    }
    fclose(pipein);
    free(buffer);
 
    }
    fclose(pipein);
    free(buffer);
 

+   // 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 " << key << std::endl;
+      std::vector<std::string>::iterator const foundItr = std::find(ValidSigners.begin(), ValidSigners.end(), key);
+      bool const found = (foundItr != ValidSigners.end());
+      std::copy(GoodSigners.begin(), GoodSigners.end(), std::back_insert_iterator<std::vector<std::string> >(NoPubKeySigners));
+      if (found)
+      {
+        // we look for GOODSIG here as well as an expired sig is a valid sig as well (but not a good one)
+        std::string const goodlongkeyid = "GOODSIG " + key.substr(24, 16);
+        bool const foundGood = std::find(GoodSigners.begin(), GoodSigners.end(), goodlongkeyid) != GoodSigners.end();
+        if (Debug == true)
+           std::clog << "Key " << key << " is valid sig, is " << goodlongkeyid << " also a good one? " << (foundGood ? "yes" : "no") << std::endl;
+        GoodSigners.clear();
+        if (foundGood)
+        {
+           GoodSigners.push_back(goodlongkeyid);
+           NoPubKeySigners.erase(std::remove(NoPubKeySigners.begin(), NoPubKeySigners.end(), goodlongkeyid), NoPubKeySigners.end());
+        }
+      }
+      else
+        GoodSigners.clear();
+   }
+

    int status;
    waitpid(pid, &status, 0);
    if (Debug == true)
    int status;
    waitpid(pid, &status, 0);
    if (Debug == true)


@@ -165,8 +251,18 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
    
    if (WEXITSTATUS(status) == 0)
    {
    
    if (WEXITSTATUS(status) == 0)
    {

-      if (GoodSigners.empty())
-         return _("Internal error: Good signature, but could not determine key fingerprint?!");
+      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 "";
    }
    else if (WEXITSTATUS(status) == 1)


@@ -185,15 +281,16 @@ string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
       return _("Unknown error executing apt-key");
 }
 
       return _("Unknown error executing apt-key");
 }
 

-bool GPGVMethod::Fetch(FetchItem *Itm)
+bool GPGVMethod::URIAcquire(std::string const &Message, FetchItem *Itm)

 {
 {

-   URI Get = Itm->Uri;
-   string Path = Get.Host + Get.Path; // To account for relative paths
-   string keyID;
+   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<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;
    vector<string> NoPubKeySigners;
    
    FetchResult Res;


@@ -201,9 +298,22 @@ bool GPGVMethod::Fetch(FetchItem *Itm)
    URIStart(Res);
 
    // Run apt-key on file, extract contents and get the key ID of the signer
    URIStart(Res);
 
    // Run apt-key on file, extract contents and get the key ID of the signer

-   string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(),
+   string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(), key,

                                  GoodSigners, BadSigners, WorthlessSigners,
                                  GoodSigners, BadSigners, WorthlessSigners,

-                                 NoPubKeySigners);
+                                 SoonWorthlessSigners, NoPubKeySigners);
+
+
+   // Check if there are any good signers that are not soon worthless
+   std::vector<std::string> NotWarnAboutSigners(GoodSigners);
+   for (auto const & Signer : SoonWorthlessSigners)
+      NotWarnAboutSigners.erase(std::remove(NotWarnAboutSigners.begin(), NotWarnAboutSigners.end(), "GOODSIG " + Signer.key));
+   // If all signers are soon worthless, report them.
+   if (NotWarnAboutSigners.empty()) {
+      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;
    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
    {
       string errmsg;


@@ -265,7 +375,5 @@ int main()
 
    GPGVMethod Mth;
 
 
    GPGVMethod Mth;
 

-   Mth.DropPrivsOrDie();
-

    return Mth.Run();
 }
    return Mth.Run();
 }