Do not parse Status fields from remote sources

This could allow an attacker to mark a package as installed in a
remote package index, as long as the package was not listed in
the dpkg status file.

This way, an attacker could force the installation of a package
during a dist-upgrade, by providing two packages in an index,
an older marked as installed, and a newer - apt would "upgrade"
to the newer version.

3 files changed, 14 insertions, 2 deletions

diff --git a/apt-pkg/deb/debindexfile.cc b/apt-pkg/deb/debindexfile.cc
index 504db919b..de6371ace 100644
--- a/apt-pkg/deb/debindexfile.cc
+++ b/apt-pkg/deb/debindexfile.cc
@@ -621,7 +621,7 @@ bool debStatusIndex::Merge(pkgCacheGenerator &Gen,OpProgress *Prog) const
    FileFd Pkg(File,FileFd::ReadOnly, FileFd::Extension);
    if (_error->PendingError() == true)
       return false;
-   debListParser Parser(&Pkg);
+   debStatusListParser Parser(&Pkg);
    if (_error->PendingError() == true)
       return false;
 
diff --git a/apt-pkg/deb/deblistparser.cc b/apt-pkg/deb/deblistparser.cc
index 6d4fd9ac1..336414775 100644
--- a/apt-pkg/deb/deblistparser.cc
+++ b/apt-pkg/deb/deblistparser.cc
@@ -333,7 +333,7 @@ unsigned short debListParser::VersionHash()
    return Result;
 }
 									/*}}}*/
-// ListParser::ParseStatus - Parse the status field			/*{{{*/
+// StatusListParser::ParseStatus - Parse the status field		/*{{{*/
 // ---------------------------------------------------------------------
 /* Status lines are of the form,
      Status: want flag status
@@ -345,6 +345,11 @@ unsigned short debListParser::VersionHash()
 bool debListParser::ParseStatus(pkgCache::PkgIterator &Pkg,
 				pkgCache::VerIterator &Ver)
 {
+   return true;
+}
+bool debStatusListParser::ParseStatus(pkgCache::PkgIterator &Pkg,
+				pkgCache::VerIterator &Ver)
+{
    const char *Start;
    const char *Stop;
    if (Section.Find("Status",Start,Stop) == false)
diff --git a/apt-pkg/deb/deblistparser.h b/apt-pkg/deb/deblistparser.h
index db7afa73c..d479997a3 100644
--- a/apt-pkg/deb/deblistparser.h
+++ b/apt-pkg/deb/deblistparser.h
@@ -117,4 +117,11 @@ class debTranslationsParser : public debListParser
       : debListParser(File, Arch) {};
 };
 
+class APT_HIDDEN debStatusListParser : public debListParser
+{
+ public:
+   virtual bool ParseStatus(pkgCache::PkgIterator &Pkg,pkgCache::VerIterator &Ver);
+   debStatusListParser(FileFd *File)
+      : debListParser(File) {};
+};
 #endif