error in update on Release information changes

The value of Origin, Label, Codename and co can be used in user
configuration from apts own pinning to unattended upgrades.
A repository changing this values can therefore have serious effects on
the behaviour of apt and other tools using these values.

In a first step we will generate error messages for these changes now
explaining the need for explicit confirmation and provide config options
and commandline flags to accept them.

1 files changed, 55 insertions, 5 deletions

diff --git a/apt-pkg/acquire-item.cc b/apt-pkg/acquire-item.cc
index 574ef4939..f5ff8288b 100644
--- a/apt-pkg/acquire-item.cc
+++ b/apt-pkg/acquire-item.cc
@@ -1605,13 +1605,63 @@ bool pkgAcqMetaBase::VerifyVendor(string const &)			/*{{{*/
    if (TransactionManager->MetaIndexParser->CheckDist(ExpectedDist) == false)
       _error->Warning(_("Conflicting distribution: %s (expected %s but got %s)"),
 	    Desc.Description.c_str(), ExpectedDist.c_str(), NowCodename.c_str());
-   // might be okay, might be not
+
+   // changed info potentially breaks user config like pinning
    if (TransactionManager->LastMetaIndexParser != nullptr)
    {
-      auto const LastCodename = TransactionManager->LastMetaIndexParser->GetCodename();
-      if (LastCodename.empty() == false && NowCodename.empty() == false && LastCodename != NowCodename)
-	 _error->Warning(_("Conflicting distribution: %s (expected %s but got %s)"),
-	       Desc.Description.c_str(), LastCodename.c_str(), NowCodename.c_str());
+      auto const AllowInfoChange = _config->FindB("Acquire::AllowReleaseInfoChange", false);
+      auto const quietInfoChange = _config->FindB("quiet::ReleaseInfoChange", false);
+      struct {
+	 char const * const Type;
+	 bool const Allowed;
+	 decltype(&metaIndex::GetOrigin) const Getter;
+      } checkers[] = {
+	 { "Origin", AllowInfoChange, &metaIndex::GetOrigin },
+	 { "Label", AllowInfoChange, &metaIndex::GetLabel },
+	 { "Version", true, &metaIndex::GetVersion }, // numbers change all the time, that is okay
+	 { "Suite", AllowInfoChange, &metaIndex::GetSuite },
+	 { "Codename", AllowInfoChange, &metaIndex::GetCodename },
+	 { nullptr, false, nullptr }
+      };
+      auto const CheckReleaseInfo = [&](char const * const Type, bool const AllowChange, decltype(checkers[0].Getter) const Getter) {
+	 std::string const Last = (TransactionManager->LastMetaIndexParser->*Getter)();
+	 std::string const Now = (TransactionManager->MetaIndexParser->*Getter)();
+	 if (Last == Now)
+	    return true;
+         auto const Allow = _config->FindB(std::string("Acquire::AllowReleaseInfoChange::").append(Type), AllowChange);
+	 auto const msg = _("Repository '%s' changed its '%s' value from '%s' to '%s'");
+	 if (Allow == false)
+	    _error->Error(msg, Desc.Description.c_str(), Type, Last.c_str(), Now.c_str());
+	 else if (_config->FindB(std::string("quiet::ReleaseInfoChange::").append(Type), quietInfoChange) == false)
+	    _error->Notice(msg, Desc.Description.c_str(), Type, Last.c_str(), Now.c_str());
+	 return Allow;
+      };
+      bool CRI = true;
+      for (short i = 0; checkers[i].Type != nullptr; ++i)
+	 if (CheckReleaseInfo(checkers[i].Type, checkers[i].Allowed, checkers[i].Getter) == false)
+	    CRI = false;
+
+      {
+	 auto const Last = TransactionManager->LastMetaIndexParser->GetDefaultPin();
+	 auto const Now = TransactionManager->MetaIndexParser->GetDefaultPin();
+	 if (Last != Now)
+	 {
+	    auto const Allow = _config->FindB("Acquire::AllowReleaseInfoChange::DefaultPin", AllowInfoChange);
+	    auto const msg = _("Repository '%s' changed its default priority for %s from %hi to %hi.");
+	    if (Allow == false)
+	       _error->Error(msg, Desc.Description.c_str(), "apt_preferences(5)", Last, Now);
+	    else if (_config->FindB("quiet::ReleaseInfoChange::DefaultPin", quietInfoChange) == false)
+	       _error->Notice(msg, Desc.Description.c_str(), "apt_preferences(5)", Last, Now);
+	    CRI &= Allow;
+	 }
+      }
+      if (CRI == false)
+      {
+	 // TRANSLATOR: %s is the name of the manpage in question, e.g. apt-secure(8)
+	 _error->Notice(_("This must be accepted explicitly before updates for "
+		  "this repository can be applied. See %s manpage for details."), "apt-secure(8)");
+	 return false;
+      }
    }
    return true;
 }