disable privilege-drop verification by default as fakeroot trips over it

[apt.git] / apt-pkg / contrib / fileutl.cc

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 368380af7817837f5c37a3ee8afa1c56be94e2ff..014f0ee51659953d3d2b1a604acc2462c6fb76ed 100644 (file)
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -169,6 +169,21 @@ bool CopyFile(FileFd &From,FileFd &To)
         return false;
    } while (ToRead != 0);
 
         return false;
    } while (ToRead != 0);
 

+   return true;
+}
+                                                                       /*}}}*/
+bool RemoveFile(char const * const Function, std::string const &FileName)/*{{{*/
+{
+   if (FileName == "/dev/null")
+      return true;
+   errno = 0;
+   if (unlink(FileName.c_str()) != 0)
+   {
+      if (errno == ENOENT)
+        return true;
+
+      return _error->WarningE(Function,_("Problem unlinking the file %s"), FileName.c_str());
+   }

    return true;
 }
                                                                        /*}}}*/
    return true;
 }
                                                                        /*}}}*/


@@ -1135,13 +1150,13 @@ bool FileFd::Open(string FileName,unsigned int const Mode,APT::Configuration::Co
    else if ((OpenMode & (Exclusive | Create)) == (Exclusive | Create))
    {
       // for atomic, this will be done by rename in Close()
    else if ((OpenMode & (Exclusive | Create)) == (Exclusive | Create))
    {
       // for atomic, this will be done by rename in Close()

-      unlink(FileName.c_str());
+      RemoveFile("FileFd::Open", FileName);

    }
    if ((OpenMode & Empty) == Empty)
    {
       struct stat Buf;
       if (lstat(FileName.c_str(),&Buf) == 0 && S_ISLNK(Buf.st_mode))
    }
    if ((OpenMode & Empty) == Empty)
    {
       struct stat Buf;
       if (lstat(FileName.c_str(),&Buf) == 0 && S_ISLNK(Buf.st_mode))

-        unlink(FileName.c_str());
+        RemoveFile("FileFd::Open", FileName);

    }
 
    int fileflags = 0;
    }
 
    int fileflags = 0;


@@ -2025,8 +2040,7 @@ bool FileFd::Close()
 
    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
        FileName.empty() == false)
 
    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
        FileName.empty() == false)

-      if (unlink(FileName.c_str()) != 0)
-        Res &= _error->WarningE("unlnk",_("Problem unlinking the file %s"), FileName.c_str());
+      Res &= RemoveFile("FileFd::Close", FileName);

 
    if (Res == false)
       Flags |= Fail;
 
    if (Res == false)
       Flags |= Fail;


@@ -2076,7 +2090,7 @@ bool FileFd::FileFdError(const char *Description,...) {
 }
                                                                        /*}}}*/
 
 }
                                                                        /*}}}*/
 

-APT_DEPRECATED gzFile FileFd::gzFd() {
+gzFile FileFd::gzFd() {

 #ifdef HAVE_ZLIB
    return d->gz;
 #else
 #ifdef HAVE_ZLIB
    return d->gz;
 #else


@@ -2266,9 +2280,15 @@ bool DropPrivileges()                                                    /*{{{*/
    // empty setting disables privilege dropping - this also ensures
    // backward compatibility, see bug #764506
    const std::string toUser = _config->Find("APT::Sandbox::User");
    // empty setting disables privilege dropping - this also ensures
    // backward compatibility, see bug #764506
    const std::string toUser = _config->Find("APT::Sandbox::User");

-   if (toUser.empty())
+   if (toUser.empty() || toUser == "root")

       return true;
 
       return true;
 

+   // a lot can go wrong trying to drop privileges completely,
+   // so ideally we would like to verify that we have done it –
+   // but the verify asks for too much in case of fakeroot (and alike)
+   // [Specific checks can be overridden with dedicated options]
+   bool const VerifySandboxing = _config->FindB("APT::Sandbox::Verify", false);
+

    // uid will be 0 in the end, but gid might be different anyway
    uid_t const old_uid = getuid();
    gid_t const old_gid = getgid();
    // uid will be 0 in the end, but gid might be different anyway
    uid_t const old_uid = getuid();
    gid_t const old_gid = getgid();


@@ -2308,51 +2328,68 @@ bool DropPrivileges()                                                   /*{{{*/
       return _error->Errno("seteuid", "Failed to seteuid");
 #endif
 
       return _error->Errno("seteuid", "Failed to seteuid");
 #endif
 

-   // Verify that the user has only a single group, and the correct one
-   gid_t groups[1];
-   if (getgroups(1, groups) != 1)
-      return _error->Errno("getgroups", "Could not get new groups");
-   if (groups[0] != pw->pw_gid)
-      return _error->Error("Could not switch group");
-
-   // Verify that gid, egid, uid, and euid changed
-   if (getgid() != pw->pw_gid)
-      return _error->Error("Could not switch group");
-   if (getegid() != pw->pw_gid)
-      return _error->Error("Could not switch effective group");
-   if (getuid() != pw->pw_uid)
-      return _error->Error("Could not switch user");
-   if (geteuid() != pw->pw_uid)
-      return _error->Error("Could not switch effective user");
+   // disabled by default as fakeroot doesn't implement getgroups currently (#806521)
+   if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::Groups", false) == true)
+   {
+      // Verify that the user isn't still in any supplementary groups
+      long const ngroups_max = sysconf(_SC_NGROUPS_MAX);
+      std::unique_ptr<gid_t[]> gidlist(new gid_t[ngroups_max]);
+      if (unlikely(gidlist == NULL))
+        return _error->Error("Allocation of a list of size %lu for getgroups failed", ngroups_max);
+      ssize_t gidlist_nr;
+      if ((gidlist_nr = getgroups(ngroups_max, gidlist.get())) < 0)
+        return _error->Errno("getgroups", "Could not get new groups (%lu)", ngroups_max);
+      for (ssize_t i = 0; i < gidlist_nr; ++i)
+        if (gidlist[i] != pw->pw_gid)
+           return _error->Error("Could not switch group, user %s is still in group %d", toUser.c_str(), gidlist[i]);
+   }
+
+   // enabled by default as all fakeroot-lookalikes should fake that accordingly
+   if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::IDs", true) == true)
+   {
+      // Verify that gid, egid, uid, and euid changed
+      if (getgid() != pw->pw_gid)
+        return _error->Error("Could not switch group");
+      if (getegid() != pw->pw_gid)
+        return _error->Error("Could not switch effective group");
+      if (getuid() != pw->pw_uid)
+        return _error->Error("Could not switch user");
+      if (geteuid() != pw->pw_uid)
+        return _error->Error("Could not switch effective user");

 
 #ifdef HAVE_GETRESUID
 
 #ifdef HAVE_GETRESUID

-   // verify that the saved set-user-id was changed as well
-   uid_t ruid = 0;
-   uid_t euid = 0;
-   uid_t suid = 0;
-   if (getresuid(&ruid, &euid, &suid))
-      return _error->Errno("getresuid", "Could not get saved set-user-ID");
-   if (suid != pw->pw_uid)
-      return _error->Error("Could not switch saved set-user-ID");
+      // verify that the saved set-user-id was changed as well
+      uid_t ruid = 0;
+      uid_t euid = 0;
+      uid_t suid = 0;
+      if (getresuid(&ruid, &euid, &suid))
+        return _error->Errno("getresuid", "Could not get saved set-user-ID");
+      if (suid != pw->pw_uid)
+        return _error->Error("Could not switch saved set-user-ID");

 #endif
 
 #ifdef HAVE_GETRESGID
 #endif
 
 #ifdef HAVE_GETRESGID

-   // verify that the saved set-group-id was changed as well
-   gid_t rgid = 0;
-   gid_t egid = 0;
-   gid_t sgid = 0;
-   if (getresgid(&rgid, &egid, &sgid))
-      return _error->Errno("getresuid", "Could not get saved set-group-ID");
-   if (sgid != pw->pw_gid)
-      return _error->Error("Could not switch saved set-group-ID");
+      // verify that the saved set-group-id was changed as well
+      gid_t rgid = 0;
+      gid_t egid = 0;
+      gid_t sgid = 0;
+      if (getresgid(&rgid, &egid, &sgid))
+        return _error->Errno("getresuid", "Could not get saved set-group-ID");
+      if (sgid != pw->pw_gid)
+        return _error->Error("Could not switch saved set-group-ID");

 #endif
 #endif

+   }

 
 

-   // Check that uid and gid changes do not work anymore
-   if (pw->pw_gid != old_gid && (setgid(old_gid) != -1 || setegid(old_gid) != -1))
-      return _error->Error("Could restore a gid to root, privilege dropping did not work");
+   // disabled as fakeroot doesn't forbid (by design) (re)gaining root from unprivileged
+   if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::Regain", false) == true)
+   {
+      // Check that uid and gid changes do not work anymore
+      if (pw->pw_gid != old_gid && (setgid(old_gid) != -1 || setegid(old_gid) != -1))
+        return _error->Error("Could restore a gid to root, privilege dropping did not work");

 
 

-   if (pw->pw_uid != old_uid && (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
-      return _error->Error("Could restore a uid to root, privilege dropping did not work");
+      if (pw->pw_uid != old_uid && (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
+        return _error->Error("Could restore a uid to root, privilege dropping did not work");
+   }

 
    return true;
 }
 
    return true;
 }