elf: Also try DT_RUNPATH for LD_AUDIT dlopen [BZ #28455]

DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry.  Update
LD_AUDIT dlopen call to try the DT_RUNPATH entry of the executable.

Add tst-audit14a, which is copied from tst-audit14, to DT_RUNPATH and
build tst-audit14 with -Wl,--disable-new-dtags to test DT_RPATH.

This partially fixes BZ #28455.

elf/Makefile

@@ -353,10 +353,10 @@ ifneq ($(selinux-enabled),1)
 tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
 endif
 ifeq ($(have-depaudit),yes)
-tests += tst-audit14 tst-audit15 tst-audit16
+tests += tst-audit14 tst-audit15 tst-audit16 tst-audit14a
 ifeq ($(run-built-tests),yes)
 tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \
-		 $(objpfx)tst-audit16-cmp.out
+		 $(objpfx)tst-audit16-cmp.out $(objpfx)tst-audit14a-cmp.out
 endif
 endif
 endif
@@ -1825,9 +1825,11 @@ $(objpfx)tst-auditmany.out: $(objpfx)tst-auditmanymod1.so \
 tst-auditmany-ENV = \
   LD_AUDIT=tst-auditmanymod1.so:tst-auditmanymod2.so:tst-auditmanymod3.so:tst-auditmanymod4.so:tst-auditmanymod5.so:tst-auditmanymod6.so:tst-auditmanymod7.so:tst-auditmanymod8.so:tst-auditmanymod9.so
 
-LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
+LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so,--disable-new-dtags
 $(objpfx)tst-auditlogmod-1.so: $(libsupport)
 $(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
+LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags
+$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so
 LDFLAGS-tst-audit15 = \
   -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
 $(objpfx)tst-auditlogmod-2.so: $(libsupport)
@@ -1854,6 +1856,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so
 $(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out
 	cmp $^ > $@; \
 	$(evaluate-test)
+$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out
+	cmp $^ > $@; \
+	$(evaluate-test)
 $(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out
 	cmp $^ > $@; \
 	$(evaluate-test)

elf/dl-load.c

@@ -2111,6 +2111,21 @@ _dl_map_object (struct link_map *loader, const char *name,
 			    &main_map->l_rpath_dirs,
 			    &realname, &fb, loader ?: main_map, LA_SER_RUNPATH,
 			    &found_other_class);
+
+	  /* Also try DT_RUNPATH in the executable for LD_AUDIT dlopen
+	     call.  */
+	  if (__glibc_unlikely (mode & __RTLD_AUDIT)
+	      && fd == -1 && !did_main_map
+	      && main_map != NULL && main_map->l_type != lt_loaded)
+	    {
+	      struct r_search_path_struct l_rpath_dirs;
+	      l_rpath_dirs.dirs = NULL;
+	      if (cache_rpath (main_map, &l_rpath_dirs,
+			       DT_RUNPATH, "RUNPATH"))
+		fd = open_path (name, namelen, mode, &l_rpath_dirs,
+				&realname, &fb, loader ?: main_map,
+				LA_SER_RUNPATH, &found_other_class);
+	    }
 	}
 
       /* Try the LD_LIBRARY_PATH environment variable.  */

elf/tst-audit14a.c

@@ -0,0 +1 @@
+#include "tst-audit14.c"