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reset HOME, USER(NAME), TMPDIR & SHELL in DropPrivileges

We can't cleanup the environment like e.g. sudo would do as you usually
want the environment to "leak" into these helpers, but some variables
like HOME should really not have still the value of the root user – it
could confuse the helpers (USER) and HOME isn't accessible anyhow.

Closes: 842877
David Kalnischkies 7 years ago
parent
commit
34b491e735

+ 20 - 0
apt-pkg/contrib/fileutl.cc

@@ -3051,6 +3051,26 @@ bool DropPrivileges()							/*{{{*/
 	 return _error->Error("Could restore a uid to root, privilege dropping did not work");
    }
 
+   if (_config->FindB("APT::Sandbox::ResetEnvironment", true))
+   {
+      setenv("HOME", pw->pw_dir, 1);
+      setenv("USER", pw->pw_name, 1);
+      setenv("USERNAME", pw->pw_name, 1);
+      setenv("LOGNAME", pw->pw_name, 1);
+      auto const shell = flNotDir(pw->pw_shell);
+      if (shell == "false" || shell == "nologin")
+	 setenv("SHELL", "/bin/sh", 1);
+      else
+	 setenv("SHELL", pw->pw_shell, 1);
+      auto const tmpdir = getenv("TMPDIR");
+      if (tmpdir != nullptr)
+      {
+	 auto const ourtmpdir = GetTempDir();
+	 if (ourtmpdir != tmpdir)
+	    setenv("TMPDIR", ourtmpdir.c_str(), 1);
+      }
+   }
+
    return true;
 }
 									/*}}}*/

+ 1 - 1
debian/tests/run-tests

@@ -13,7 +13,7 @@ make -C build/test/interactive-helper
 # the host env does not pollute our environment
 env -i \
 APT_INTEGRATION_TESTS_SOURCE_DIR=$(pwd) \
-APT_INTEGRATION_TESTS_WEBSERVER_BIN_DIR=$(pwd)/build/test/interactive-helper \
+APT_INTEGRATION_TESTS_HELPERS_BIN_DIR=$(pwd)/build/test/interactive-helper \
 APT_INTEGRATION_TESTS_METHODS_DIR=/usr/lib/apt/methods \
 APT_INTEGRATION_TESTS_LIBEXEC_DIR=/usr/lib/apt/ \
 APT_INTEGRATION_TESTS_INTERNAL_SOLVER=/usr/lib/apt/solvers/apt \

+ 3 - 3
test/integration/framework

@@ -190,7 +190,7 @@ aptmark() { runapt apt-mark "$@"; }
 aptsortpkgs() { runapt apt-sortpkgs "$@"; }
 apt() { runapt apt "$@"; }
 apthelper() { runapt "${APTHELPERBINDIR}/apt-helper" "$@"; }
-aptwebserver() { runapt "${APTWEBSERVERBINDIR}/aptwebserver" "$@"; }
+aptwebserver() { runapt "${APTTESTHELPERSBINDIR}/aptwebserver" "$@"; }
 aptitude() { runapt aptitude "$@"; }
 aptextracttemplates() { runapt apt-extracttemplates "$@"; }
 aptinternalsolver() { runapt "${APTINTERNALSOLVER}" "$@"; }
@@ -331,7 +331,7 @@ setupenvironment() {
 	LIBRARYPATH="${APT_INTEGRATION_TESTS_LIBRARY_PATH:-"${BUILDDIRECTORY}/../apt-pkg"}"
         METHODSDIR="${APT_INTEGRATION_TESTS_METHODS_DIR:-"${BUILDDIRECTORY}/../methods"}"
         APTHELPERBINDIR="${APT_INTEGRATION_TESTS_LIBEXEC_DIR:-"${BUILDDIRECTORY}"}"
-        APTWEBSERVERBINDIR="${APT_INTEGRATION_TESTS_WEBSERVER_BIN_DIR:-"${BUILDDIRECTORY}/../test/interactive-helper"}"
+        APTTESTHELPERSBINDIR="${APT_INTEGRATION_TESTS_HELPERS_BIN_DIR:-"${BUILDDIRECTORY}/../test/interactive-helper"}"
         APTFTPARCHIVEBINDIR="${APT_INTEGRATION_TESTS_FTPARCHIVE_BIN_DIR:-"${BUILDDIRECTORY}/../ftparchive"}"
         APTINTERNALSOLVER="${APT_INTEGRATION_TESTS_INTERNAL_SOLVER:-"${BUILDDIRECTORY}/solvers/apt"}"
 	APTDUMPSOLVER="${APT_INTEGRATION_TESTS_DUMP_SOLVER:-"${BUILDDIRECTORY}/solvers/dump"}"
@@ -1296,7 +1296,7 @@ changetowebserver() {
 	else
 		shift
 	fi
-	if test -x "${APTWEBSERVERBINDIR}/aptwebserver"; then
+	if test -x "${APTTESTHELPERSBINDIR}/aptwebserver"; then
 		cd aptarchive
 		local LOG="webserver.log"
 		if ! aptwebserver --port 0 -o aptwebserver::fork=1 -o aptwebserver::portfile='aptwebserver.port' "$@" >$LOG 2>&1 ; then

+ 32 - 0
test/integration/skip-apt-dropprivs

@@ -0,0 +1,32 @@
+#!/bin/sh
+set -e
+
+TESTDIR="$(readlink -f "$(dirname "$0")")"
+. "$TESTDIR/framework"
+
+setupenvironment
+configarchitecture 'amd64'
+
+aptdropprivs() { runapt "${APTTESTHELPERSBINDIR}/aptdropprivs" "$@"; }
+
+testsuccess aptdropprivs -- /bin/true
+testsuccess aptdropprivs --user "$USER" -- /bin/true
+testsuccess aptdropprivs --user 'nobody' -- /bin/true
+testsuccess aptdropprivs --user '_apt' -- /bin/true
+
+IDBIN='/usr/bin/id'
+testsuccessequal "$("$IDBIN")" aptdropprivs --user "$USER" -- "$IDBIN"
+
+SUDOBIN='/usr/bin/sudo'
+testequal "sudo: effective uid is not 0, is /usr/bin/sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges?" aptdropprivs --user 'nobody' -- "$SUDOBIN" "$IDBIN"
+
+if [ "$(id -u)" = '0' ]; then
+	testsuccessequal '_apt' aptdropprivs --user '_apt' -- "$IDBIN" '-un'
+	testsuccess aptdropprivs --user '_apt' -- '/bin/sh' '-c' 'export'
+	cp rootdir/tmp/testsuccess.output apt.env
+	testsuccessequal "export HOME='/nonexistent'" grep '^export HOME' apt.env
+	testsuccessequal "export USER='_apt'
+export USERNAME='_apt'" grep '^export USER' apt.env
+	testsuccessequal "export LOGNAME='_apt'" grep '^export LOGNAME' apt.env
+	testsuccessequal "export SHELL='/bin/sh'" grep '^export SHELL=' apt.env
+fi

+ 2 - 0
test/interactive-helper/CMakeLists.txt

@@ -6,6 +6,8 @@ add_executable(extract-control extract-control.cc)
 target_link_libraries(extract-control apt-pkg apt-inst)
 add_executable(aptwebserver aptwebserver.cc)
 target_link_libraries(aptwebserver apt-pkg  ${CMAKE_THREAD_LIBS_INIT})
+add_executable(aptdropprivs aptdropprivs.cc)
+target_link_libraries(aptdropprivs apt-pkg)
 add_executable(test_fileutl test_fileutl.cc)
 target_link_libraries(test_fileutl apt-pkg)
 

+ 27 - 0
test/interactive-helper/aptdropprivs.cc

@@ -0,0 +1,27 @@
+#include <config.h>
+
+#include <apt-pkg/cmndline.h>
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/error.h>
+#include <apt-pkg/fileutl.h>
+
+#include <unistd.h>
+
+int main(int const argc, const char * argv[])
+{
+   CommandLine::Args Args[] = {
+      {'c',"config-file",0,CommandLine::ConfigFile},
+      {'o',"option",0,CommandLine::ArbItem},
+      {0, "user", "APT::Sandbox::User", CommandLine::HasArg},
+      {0,0,0,0}
+   };
+
+   CommandLine CmdL(Args, _config);
+   if(CmdL.Parse(argc,argv) == false || DropPrivileges() == false)
+   {
+      _error->DumpErrors(std::cerr, GlobalError::DEBUG);
+      return 42;
+   }
+
+   return execv(CmdL.FileList[0], const_cast<char**>(CmdL.FileList));
+}